Handbook for Civil Aviation Medical Examiners

Foreword
Section 1
Section 2
Asthma
Cardiovascular
Diabetes
Neurology
Psychiatry (SSRIs)
Other Policies
Contacts

The PDF copy of the 2004 Handbook for Civil Aviation Medical Examiners has been removed to avoid confusion, as it is not the current version. If you would like a copy of it for reference purposes only, please send this request to NCRCivAvMedicineInquiries-EnquetesMedecineAeroCivRCN@tc.gc.ca

Foreword

Civil Aviation Medical Standards

The history of medical standards in civil aviation dates back to just after World War I when the International Commission on Air Navigation (ICAN) was established following the Paris Air Convention of 1919. This organization was set up to establish rules and regulations for the safe conduct of civil aviation. ICAN established a medical subcommission which set about producing the first ever medical standards for civil aircrew which were extremely strict. In 1944, towards the end of World War II, the International Civil Aviation Organization (ICAO), an agency of the United Nations, was formed to carry on the work of ICAN, which had ceased to exist during World War II. Over the years, the international standards and those of Canada have become more liberal to the point now that the majority of the population over the age of 16, if they so wished, would pass aviation medical certification examinations.

In Canada, the regulations pertaining to medical requirements are contained in Part 404 of the Canadian Aviation Regulations (CARs) while the actual medical standards are in Part 424 of the Canadian Aviation Regulations. Both Part 404 and Part 424 form part of this Handbook. CAR 424.05 permits the Civil Aviation Medicine Branch to exercise flexibility in medical certification of pilots and air traffic controllers who technically do not meet the standard, but for whom accredited medical conclusion is such that the failure to meet the standard is such that the exercise of the privilege of the licence is not likely to affect air safety.

Over the years, guidelines have been produced in the major areas which cause problems with aeromedical certification, namely neurology, cardiology and diabetes. A copy of these guidelines is available in this Handbook.

In your role as a Civil Aviation Medical Examiner (CAME), you are usually the only person who physically examines the pilot or ATC and makes a recommendation for medical certification. You are therefore the most important link in the chain of safety in the medical certification process. While performing your CAME function, you are acting as an agent of the Minister of Transport, so Transport Canada will indemnify you for any litigation that may come from your aviation medical examination activity which is conducted in good faith. Recent changes in the medical certification process, and delegation of validation authority to the examiner have not resulted in increasing the exposure to litigation, and will therefore not result in increases to malpractice insurance premiums for CAMEs.

Accompanying this book is a video outlining the changes that have taken place in the medical certification process, and showing you how to complete the Medical Examination Report form (26-0010) completely. The medical handbook part of this document is not a text on aviation medicine, it is merely an introduction to the subject and covers the basic facts that you must have to understand the medical problems associated with flight. It will help you deal with many of the questions you may be asked and hopefully will encourage you to further
study the subject. More detailed information on the subject of aviation medicine can be obtained from the following books:

Aviation Medicine - J. Ernsting, A. Nicholson and D. Rainford, Third Edition (1999), Butterworth - Heinemann.

Fundamentals of Aerospace Medicine - R. DeHart and J. Davis, Third Edition (2002), Williams and Wilkins.

Clinical Aviation Medicine - R. Raymond, Third Edition (2000), Castle Connolly Graduate Medical Publishing, LLC.

Civil Aviation Medicine Branch has developed an Internet website which will be used more and more for the dissemination of information between the Branch and CAMEs. Those of you who have Internet access are welcome to browse the website and submit your comments. The address is: https://tc.canada.ca/en/aviation/medical-fitness-aviation

Section 1

The Civil Aviation Medicine (CAM) Branch is one of several branches of the Directorate General of Civil Aviation in Transport Canada. The Director of Civil Aviation Medicine reports to the Director General of Civil Aviation.

CAM Headquarters

CAM Headquarters is located in the Transport Canada Building, 330 Sparks Street, Tower "C", Place de Ville, Ottawa, K1A 0N8.

The mandate of CAM is to provide medical advice and assistance in setting out physical standards for Civil Aviation personnel; to advise in all problems connected with the health of travellers by air.

The mission is to ensure aircrew and air traffic controllers are medically fit, to close gaps in scientific knowledge of Canadian aviation medicine, to promote health and safety in the field of aviation and to prevent aircraft accidents due to medically related human factors.

Regional Offices

There are currently four Regional offices across Canada located in Montreal, Toronto, Edmonton, and Vancouver. The Edmonton, Toronto, and Montreal offices are under the direction of a Regional Aviation Medical Officer (RAMO) while the office in Vancouver is staffed by an Aviation Medical Officer. The RAMOs are responsible for the selection and training of CAMEs, for reviewing the medical examination reports of pilots, flight engineers, and air traffic controllers, and for approving an appropriate medical category for aviation personnel. CAM does not issue licences, it issues Medical Certificates (MCs). Licensing is a responsibility of Transport Canada, General Aviation. As a CAME, you may now renew MCs, for the full validity period, of licensed aviation personnel for renewal medical examinations only. Initial medical reports, category upgrades and removal or addition of restrictions to a MC must be sent to the RAMO for assessment.

Figure 1 - Transport Canada Regions

Figure 1 - Transport Canada Regions

Licensing

All pilots, flight engineers, and air traffic controllers must be licensed by Transport Canada, General Aviation Branch. After completing such requirements as flight training, written examinations, and flight tests, an applicant is granted a licence by the department. Licences do not have a validity period, but must be validated by a current MC which has a limited duration. There are four medical categories shown on the medical certificate, each of which validates a different type of licence. The types, the required medical categories and the validity periods of the licences are shown in the Medical Examination Requirements Table. (Figure 2)

Civil Aviation Medical Examiners (CAMEs)

CAMEs are appointed on the basis of need, by the RAMO or AMO on behalf of the Minister of Transport. Interested physicians apply to the CAM office in their region and are interviewed by the RAMO prior to appointment. If accepted as a designated CAME, they must await the receipt of the official letter of appointment before performing any aviation medical examinations. The letter of appointment will be sent together with a full CAME authority package, including this Handbook, a CAME numbered stamp and a wall certificate. All CAMEs who are newly appointed will be required to
attend a training seminar at the earliest opportunity, and then no less than once every four years.

Aviation medical examinations may only be carried out by a CAME. In the case of pilots residing overseas, the examination may be carried out by a medical examiner approved by the licensing authority of a contracting state of the International Civil Aviation Organization (ICAO). Appointment of CAMEs in areas outside Canada is at the discretion
of the Senior Consultant, Operations, Policy and Standards, of Civil Aviation Medicine Branch or the Director of Civil Aviation Medicine.

All CAME appointments are valid for a period of four years, renewable upon the recommendation of the RAMO. Re-appointment will depend on the quality and timeliness of reports, demonstrated continuing interest in aviation medicine, and feedback from the aviation community. There must also be a continuing requirement for services in the CAME's designated geographic area.

Termination of Appointments

It is rare for a CAME appointment to be terminated. If there are significant problems with the quality of the medical information being submitted, the RAMO will contact the CAME and take whatever remedial action is necessary to assist in solving the problem.

Appointments may be terminated for any of the following reasons:

Frequent or continual low quality professional performance.
Failure to provide reasonably prompt service.
Unethical conduct.
Loss or suspension of medical licence.
Prolonged inability to provide service due to ill health or disability.
Change of geographic location.
Voluntary relinquishment of the appointment by a CAME.

CAMEs may, at any time, request that their appointment be terminated.

The Medical Examination

It is your responsibility to interview and perform a complete examination on all applicants for aviation medical certification. You may be the only physician in the normal course of events who has talked to the pilot and had a "hands-on" opportunity to form an impression. Although the Medical Examination Report form (MER) may look similar to others you have completed for insurance examinations, your input here is much more valuable and is of immediate importance.

Since pilots and air traffic controllers are at risk of losing their medical certificate, and in some cases their employment, each time they present themselves for a medical, they naturally find aviation medical examinations threatening. For this reason, we recommend that you and your staff do all in your power to put the applicant at ease prior to the examination. This examination is always stressful and often becomes more stressful as aviation personnel grow older.

Aviation personnel, although not basically dishonest, may not volunteer information which may affect their medical certification. They will, however, respond to direct questions and will sometimes give you much more information than you expect if you convince them that your prime interest is keeping them at work. Sometimes they have problems that may affect their medical certification that they would like to discuss with someone of good will. Of particular importance in the interview is any suggestion of substance abuse, mental instability, lack of insight or inappropriate reactions. You have an opportunity to decide whether this is the type of person with whom you would fly or to whom you would entrust your family. Remember, that the next time you climb on board as a passenger this may be your Captain!

Normally when you deal with patients you are concerned with their immediate health. In aviation a more important concept is that of sudden and/or subtle incapacitation. This may arise from such diverse stresses as the pain of acute renal colic or the subtle loss of judgment that results from an occult brain tumour. A pilot in trouble in the air cannot stop and pull over to the side of the road until the symptoms pass! A point to bear in mind is that in annual medicals we are chiefly concerned with the short term, that is, the validity period of the medical certificate.

The medical examination is recorded on the form, Medical Examination Report 26-0010 (MER), the original of which should be sent to the Regional office. The MER is available in both English and French and is periodically updated. The effective date is located in the lower left corner of the form as (1999-03). Blank forms are available upon request from the Regional offices.

The MER is reviewed in the Regional office. If the MER is not complete or if there are errors or omissions, it will be returned for correction. The original form should then be corrected and returned to the Regional office.

The next few pages will help you to fill out the MER and indicate the type of answers required. There is also an Appendix on the visual examination. This seems to be the most difficult part of the examination and so befits greater explanation. Hopefully all else will be clear after your first seminar but, if in doubt, your RAMO is no further away than your telephone (See contact numbers -Toll free).

A useful reference is the ICAO Manual of Aviation Medicine produced by the International Civil Aviation Organization. Copies of this can be obtained by writing to the following address:

(The manual is currently being revised.)

Document Sales Unit
International Civil Aviation Organization
999 University Street
Montreal, Quebec
H3C 5H7
Canada

http://www.icao.int/

Figure 2 - Medical Examination Requirement Chart

Licence or Permit Type	Medical Category	Age	Medical Report	Audiogram	Age	Electro-cardiogram
Airline Transport Senior Commercial Commercial	1	Under 40	Within twelve months of issue or revalidation	At first examination then at 55 years old	Under 30	At first examination
Airline Transport Senior Commercial Commercial		Over 40	Within six months of issue or revalidation		30-40	At first examination and every two years thereafter
(Validates all other categories)		Over 40	Within six months of issue or revalidation		Over 40	At first examination and every year thereafter
NOTE: The holder of Medical Category 1 shall be considered fit for any permit or licence for its respective duration of validity unless otherwise specified
Flight Navigator Flight Engineer Air Traffic Controller	2	Under 40	Within two years of issue or revalidation	At first examination then at 55 years old	Under 30	At first examination
		Over 40	Within twelve months of issue or revalidation		30-40	At first examination and every two years thereafter
		Over 40	Within twelve months of issue or revalidation		Over 40	At first examination and every year thereafter
* Student Pilot Private Pilot Gyroplane Pilot Free Balloon Pilot	3	Under 40	Within five years of issue or revalidation	(If clinically indicated)	Under 40	N.A.
	3	Over 40	Within two years of issue or revalidation	(If clinically indicated)	Over 40	At first examination and every four years thereafter
Ultra Light Instructor Glider Instructor	4		Within five years of issue or revalidation	(If clinically indicated)	Under 40	N.A.
Ultra Light Instructor Glider Instructor	4		Within five years of issue or revalidation	(If clinically indicated)	Over 40	At first examination and every five years thereafter
Glider Pilot Ultra Light Pilot	4		Medical Declaration (Full MER only if clinically indicated)	(If clinically indicated)		N.A.
Recreational Pilot Student Pilot	4		Medical Declaration or Form 26-0297 counter- signed by a physician	(If clinically indicated)	Under 40	N.A.
					40-50	At first examination
					Over 50	At first examination and every four years thereafter

Completing The Medical Examination Report

Part A

REGION AND HQ FILE NUMBER
- These blocks will be completed by the Region.

TYPE OF LICENCE DESIRED
- Indicate any of the types listed in Fig. 2.

AVIATION LICENCE HELD
- Indicate any of the types listed in Fig. 2.
Initial applicants should have "NIL" indicated here.

LICENCE NUMBER
- Enter the applicant's licence number if available.

TELEPHONE NUMBER
- Indicate numbers with area codes, Fax, e-mail.

NAME, FAMILY NAME AND FORMER SURNAME
- Complete legal names should be indicated here. Initials and nicknames cause confusion.

ADDRESS, CITY\COUNTRY, PROVINCE, POSTAL CODE
- Full addresses are required. Abbreviations should not be used.

PROVINCE OF RESIDENCE
- Self explanatory.

DATE OF BIRTH
- Self explanatory.

PLACE OF BIRTH (COUNTRY)
- Indicate the country only.

MALE/FEMALE
- Self explanatory.

CITIZEN OF
- Indicate citizenship.

EDUCATION
- Indicate highest level achieved e.g. Grade 12 (or University).

OCCUPATION, EMPLOYER
- Self explanatory.

PILOT FLIGHT TIME
- This can be very important. A hiatus or sudden change in flying time patterns may indicate an illness/injury which has not been revealed.
Grand total is all the flying time since the applicant started flying.

HAVE YOU HAD AN AIRCRAFT ACCIDENT...?
- Accident data is not kept on the Department of Transport pilot files. We rely on the information you provide. If the pilot answers yes, note whether there was a medical cause or any medical sequelae in the "Review of Systems" part of the form.

HAVE YOU CONSULTED A PHYSICIAN? REASON?
- Self explanatory.

AERONAUTICAL PUBLICATIONS
- Indicate the language preferred by the applicant.

PRIMARY TYPE OF FLYING INTENDED
- Recreation includes all non-business related flying. Business includes all business, commercial and military flying.

DATE OF LAST CIVIL AVIATION MEDICAL EXAMINATION
- Indicate date and place if known.

MEDICAL CATEGORY
- Indicate the medical category assigned to the applicant
at the last medical certification.

DATE OF LAST ECG, CHEST X-RAY AND AUDIOGRAM
- Show the complete date if known.

Part B

Family History
This section is included to identify people at higher risk for genetic or familial diseases. Any "yes" answers require comment in the blank space provided. There is also a block here in which you can record cardiovascular risk factors.

Review of Systems
The functional inquiry is the basis for any good medical examination. This part should be completed by you. The questions, of course, are simply a guide and are not all inclusive. A positive response should be elaborated in the space below or, if there is insufficient space, on an attached sheet.

Statement of Applicant
This is a legal declaration that the applicant has supplied complete and accurate information. It releases the medical information on the MER and other reports to CAM and Transport Canada. The applicant must read, date and sign the declaration and the signature must be witnessed. The applicant should be aware that it is an offence under the Aeronautics Act to knowingly make a false declaration.

Part D

Civil Aviation Medical Examiner's Recommendation
Most of this is self-explanatory. It is possible for a candidate who is an air traffic controller to have two categories such as 2 and 3, as the candidate could be also eligible for private pilot medical certification. The "remarks" area is for any observation or recommendation you wish to make. Part D should be signed at the end of the complete examination and must bear your personal CAME stamp.

Part C

General Physical Examination

This section should be completed by you although some portions, such as the height, weight and blood pressure may be completed by your staff. They must be trained and supervised as noted in the Canadian Medical Association (CMA) guidelines on the delegation of medical responsibilities. It is preferable that you perform the entire examination.

Height and Weight

Use metric figures.

Blood Pressure

This should be recorded while the applicant is sitting, using a cuff of appropriate size. If a non-standard cuff is used this should be recorded. The diastolic blood pressure to be recorded is the disappearance of the sound.

Identifying Marks

Note any surgical scars, tattoos or other marks. These may be useful for identification in aircraft accidents.

Nutrition

There are no Transport Canada standards for desirable or maximum weights of individuals. Record if the individual's stature would affect the ability to function in the flight environment.

Nose and Throat

The examination should be directed to the presence of any condition which would impair respiratory functions or pressure equalization during flight.

Ear Drums

Examine for any pathology, perforations and for the adequacy of pressure equalization. Pressure equalization should be assessed by observation of the drum during a Valsalva maneuver. Vestibular function should be normal.

Respiratory System

Self-explanatory.

Cardiovascular

This should include an assessment of the peripheral circulation as well as the heart. A careful note should be made of any murmurs.

Abdomen Including Hernia

Rectal examination is not mandatory but, in keeping with good medical practice, is recommended for males over age 45. An assessment of the inguinal areas for hernia is necessary, since inguinal hernias are not considered safe in the aviation environment.

Genitourinary

Self explanatory. Pelvic examination is not required.

Locomotor

Pilot applicants should be assessed for the ability to undertake flight operations in normal and emergency situations. In the case of amputation or paraplegia, special practical tests will be ordered by the RAMO to determine the applicant's suitability for flight.

Neurological

A screening examination with assessment of reflexes is required.

Mental Status

This is an overall assessment of the psychological suitability for the aircrew of air traffic controller licence. A brief comment regarding an applicant's mental stability would be appreciated in the "Remarks" section.

Integument

skin etc.

Part C - Visual Examination

Visual Examination
Note: An excellent outline of an aviation visual examination can be seen on the video, "The Vision Examination for Civil Aviation Medical Examiners" available from CAM Headquarters.

This should include examination of the external eye and direct or indirect ophthalmoscopy. Particular attention should be directed to the cornea to detect contact lenses and/or the scars of surgical procedures to correct refractive errors such as PRK and LASIK. Cycloplegic examination is not routinely required.

VISUAL FIELDS
- Assessment by confrontation is adequate.

Distant Vision Testing
The Transport Canada standards for vision are summarized in Fig. 3. Distant vision should be tested using Landolt Rings, a chart of Snellen letters or other similar opotypes situated at an optical distance of 6 meters using either an eye lane or an approved vision testing instrument. Where an eye lane is used, the test chart must be illuminated to a level equivalent to that provided by a 100 watt lightbulb placed 120 centimeters in front of, and slightly above the chart with the light shielded from the applicant. The examination room should be darkened with the exception of the chart.
The uncorrected vision should be tested initially in each eye separately, and then in both eyes. Squinting is not permitted. After the uncorrected vision is tested the corrected vision should be tested in the same manner.

Contact Lens Wearers - It is necessary to test the uncorrected vision in the initial examination without the use of lenses or provide a contact lens report from an eye care professional. They should also be tested with backup glasses prior to putting their lenses in place and the results noted beside the distant vision testing blocks.

If a contact lens wearer cannot remove his/her lenses at the initial examination, he/she should be required to return. It is not necessary to repeat examination to remove the contact lenses.

In initial applicants if the uncorrected vision is 6/60 or less the refractive error must be recorded in the space provided.

Be sure to note whether contact lenses were worn during the examination and whether you recommend an eye specialist's examination.

Near Vision
Near vision should be tested with the Faculty of Ophthalmologists Reading Type 'N' charts or equivalent. Vision in each eye separately should be tested without and then with correction. Use good "over the shoulder" illumination of the card and avoid reflections and glare. Note that the standard does not require the near vision correction to meet TC Standards in each eye separately.

Ocular Muscle Balance
Ocular muscle balance can be tested with the cover test, the Maddox rod or an approved vision tester. Report the results of the cover test in the space provided. The Maddox rod results should be noted in the appropriate spaces. Checking the orthophoria box means that there is no deviation and the other spaces can be left blank. Any deviations should be noted in the esophoria, exophoria and hyper phoria boxes.

Maddox Rod Test - This is described in detail in Appendix 1 and on the aviation vision video. The results should be recorded in the number of diopters of esophoria, etc. The use of this instrument is demonstrated in the video "The Vision Examination for Aviation Medical Examiners"

Cover Test - The purpose of this test is to determine whether manifest strabismus is present, or whether there is any tendency of the eyes to deviate when the two eyes are dissociated. The examiner stands in front of the candidate who is told to fix his eyes on a small target such as a small examining light. An occluder card is then placed in front of one eye and the other eye checked for movement. If there is none the card is removed and the covered eye examined to see whether it has remained fixed or whether it has moved medially or laterally and has to be re-fixated. The test is then repeated with the other eye covered.

If the candidate is orthophoric no movement of the eyes will take place. If there is esophoria one eye will move in and then re-fixate when the occluder is removed. In exophoria the opposite is true. It should be noted that less than 10% of individuals are orthophoric!

Colour Perception
Colour perception should be tested at each aviation medical examination because various eye diseases may cause a change or deterioration. Colour vision may be tested with any of the standard pseudo-isochromatic test plate sets noted in Appendix 2. Appropriate lighting must be provided for testing. If a special colour balanced light source is not used, daylight is best for screening. Be wary of fluorescent or incandescent lights which may cause inaccurate readings. The type of plates (Pseudo-isochromatic, Ishihara etc.), the number of plates in the set (versus the number that should be used for testing) and the number of errors should be noted.

An applicant failing colour plate testing may have a colour lantern or a Farnsworth D-15 Hue test performed. These tests are available at a number of locations across the country or CAM regional offices.
Note: The colour lantern test is not acceptable for initial air traffic controller applicants, who must pass the plates or a Farnsworth D-15 Hue test.

Part C - Hearing Examination

Hearing Examination
This should be tested with the whispered voice. The applicant must be able to hear and understand at a distance greater than 2 metres. Testing with screening audioscope is acceptable. Abnormalities noted on the screening test should prompt testing by pure tone audiometry. Candidates for Category 1 or 2 medical certification will require a pure tone audiogram at the initial examination.

Urinalysis
Routine dip-stick testing of the urine for glucose is required at each aviation medical examination. Microscopic examination is only required where clinically indicated.

Other tests
- Self-explanatory.

Part C - Renewing a Medical Certificate

If an applicant who has a licence meets all the medical standards in CAR 424 you may renew his/her Medical Certificate (MC) and mark the FIT box on the MER form. You cannot grant additional privileges. For example, if an applicant with a restriction such as "Valid only when wearing required glasses" presents for medical certification with contact lenses, you can only extend the present privileges, not give authorization for him/her to use contact lenses when flying. This must be done by CAM. In the same way you cannot give authorization for an upgrade from one medical category to another.

Initial applicants do not have a MC so you cannot grant them a medical category and can only mark the DEFERRED box, indicating "initial applicant" under the remarks area.

If an applicant does not present a MC for signature you cannot renew, but only mark DEFER and indiate "no MC available" under the remarks area.

If an applicant wishes to upgrade from a Category 3 to Category 1, complete the examination, arrange for an ECG and audiogram to be submitted with the MER, and renew the existing Cat 3 MC for the full period. If the applicant meets the Category 1 standard then a new multi sign off Category 1 MC will be sent to him\her by Transport Canada.

If renewal has been granted, mark "yes" in the "Was a renewal assigned" block on the MER. If it was not granted mark "no", check the DEFERRED box, and indicate the reason in the space underneath. Also indicate whether further examination is recommended and whether a separate confidential report is being submitted.

Note: If you do not believe an applicant is fit for the category requested, DO NOT RENEW THE MC, mark the DEFERRED box in part "D" of the MER, and add your comments, either in the remarks section or in a confidential report.

The examination form and all additional test results are then forwarded to the RAMO. A copy should be retained in your office for a minimum of six months, but it is wise to retain the copies indefinitely as with any medical record, particularly in the present climate of medico-legal litigation.

Special Renewal
A small number of licensed personnel will have been issued with a MC that has been endorsed over the renewal boxes "Not valid for CAME renewal".
In these cases, send in the medical examination report and any other reports/tests that have been requested. Mark the "depressed" box in Part "D". The applicant will be issued with a new MC at each examination.

Civil Aviation Medical Examination Report Form

Civil Aviation Medical Examination Report

Completing the Medical Examination Report Form

This section deals specifically with the completion of the form.

BLOCK LETTERS OR TYPING SHOULD BE USED

Part A

Region and HQ File Number

These blocks will be completed by the Region.

Type of Licence/Permit Desired

Indicate any of the types listed in Fig. 2.

Aviation Licence/Permit Held

Indicate any of the types listed in Fig. 2. Initial applicants should have "NIL" indicated here.

Permit/Licence Number

Enter the applicant's permit/licence number if available.

Telephone Number

Indicate numbers with area codes, Fax, e-mail.

Name, Family Name and Former Surname

Complete legal names should be indicated here. Initials and nicknames cause confusion.

Address, City\Country, Province, Postal Code

Full addresses are required. Abbreviations should not be used.

Country of Residence

Self explanatory.

Date of Birth

Self explanatory.

Place of Birth (Country)

Indicate the country only.

Male/Female

Self explanatory.

Citizen of

Indicate citizenship.

Education

Indicate highest level achieved e.g. Grade 12 (or University).

Occupation, Employer

Self explanatory.

Pilot Flight Time

This can be very important. A hiatus or sudden change in flying time patterns may indicate an illness/injury which has not been revealed. Grand total is all the flying time since the applicant started flying.

Have you had an aircraft accident...?

Accident data is not kept on the Department of Transport pilot files. We rely on the information you provide. If the pilot answers yes, note whether there was a medical cause or any medical sequelae in the "Review of Systems" part of the form.

Have you consulted a physician? Reason?

Self explanatory.

Aeronautical Publications

Indicate the language preferred by the applicant.

Primary Type of Flying Intended

Recreation includes all non-business related flying. Business includes all business, commercial and military flying.

Date of Last Civil Aviation Medical Examination

Indicate date and place if known.

Date of Last ECG, Chest X-ray and Audiogram

Show the complete date if known.

Note: If you are examining the applicant for the first time ask for proof of identity, preferably photo ID!

Part B

Family History

This section is included to identify people at higher risk for genetic or familial diseases. Any "yes" answers require comment in the blank space provided. There is also a block here in which you can record cardiovascular risk factors.

Review of Systems

The functional inquiry is the basis for any good medical examination. This part should be completed by you. The questions, of course, are simply a guide and are not all inclusive. A positive response should be elaborated in the space below or, if there is insufficient space, on an attached sheet.

Statement of Applicant

This is a legal declaration that the applicant has supplied complete and accurate information. It releases the medical information on the MER and other reports to CAM and Transport Canada. The applicant must read, date and sign the declaration and the signature must be witnessed. The applicant should be aware that it is an offence under the Aeronautics Act to knowingly make a false declaration.

Part D

Civil Aviation Medical Examiner's Recommendation

Most of this is self-explanatory. It is possible for a candidate who is an air traffic controller to have two categories such as 2 and 3, as the candidate could be also eligible for private pilot medical certification. The "remarks" area is for any observation or recommendation you wish to make. Part D should be signed at the end of the complete examination and must bear your personal CAME stamp.

Part C

General Physical Examination

This section should be completed by you although some portions, such as the height, weight and blood pressure may be completed by your staff. They must be trained and supervised, and appropriately 'delegated' in accordance with the policy of your medical licensing authority. It is preferable that you perform the entire examination.

Height and Weight

Use metric figures.

Blood Pressure

This should be recorded while the applicant is sitting, using a cuff of appropriate size. If a nonstandard cuff is used this should be recorded. The diastolic blood pressure to be recorded is the disappearance of the sound.

Identifying Marks

Note any surgical scars, tattoos or other marks. These may be useful for identification in aircraft accidents.

Nutrition

There are no Transport Canada standards for desirable or maximum weights of individuals. Body Mass Index (BMI) is a useful indicator of a healthy weight. (See Chart 1.)
BMI = Weight in Kg divided by the height in metres²
The ideal BMI range is 20-25

Nose and Throat

The examination should be directed to the presence of any condition which would impair respiratory functions or pressure equalization during flight.

Ear Drums

Examine for any pathology, perforations and for the adequacy of pressure equalization. Pressure equalization should be assessed by observation of the drum during a Valsalva maneuver. Vestibular function should be normal.

Respiratory System

Self-explanatory.

Cardiovascular

This should include an assessment of the peripheral circulation as well as the heart. A careful note should be made of any murmurs.

Abdomen Including Hernia

Rectal examination is not mandatory but, in keeping with good medical practice, is recommended for males over age 45. An assessment of the inguinal areas for hernia is necessary, since inguinal hernias are not considered safe in the aviation environment.

Genitourinary

Self explanatory. Pelvic examination is not required.

Locomotor

Pilot applicants should be assessed for the ability to undertake flight operations in normal and emergency situations. In the case of amputation or paraplegia, special practical tests will be ordered by the RAMO to determine the applicant's suitability for flight.

Neurological

A screening examination with assessment of reflexes is required.

Mental Status

This is an overall assessment of the psychological suitability for the aircrew of air traffic controller licence. A brief comment regarding an applicant's mental stability would be appreciated in the "Remarks" section.

Integument

skin etc.

Visual Examination

Note: An excellent outline of an aviation visual examination can be seen on the video, "The Vision Examination for Civil Aviation Medical Examiners" available from CAM Headquarters. This should include examination of the external eye and direct or indirect ophthalmoscopy. Particular attention should be directed to the cornea to detect contact lenses and/or the scars of surgical procedures to correct refractive errors such as PRK and LASIK. Cycloplegic examination is not routinely required.

Chart 1 - Body Mass Index (BMI)

Chart 1 - Body Mass Index (BMI)

Visual Fields

Assessment by confrontation is adequate.

Distant Vision Testing

The Transport Canada standards for vision are summarized in Fig. 3. Distant vision should be tested using Landolt Rings, a chart of Snellen letters or other similar opotypes situated at an optical distance of 6 meters using either an eye lane or an approved vision testing instrument. Where an eye lane is used, the test chart must be illuminated to a level equivalent to that provided by a 100 watt lightbulb placed 120 centimeters in front of, and slightly above the chart with the light shielded from the applicant. The examination room should be darkened with the exception of the chart.

The uncorrected vision should be tested initially in each eye separately, and then in both eyes. Squinting is not permitted. After the uncorrected vision is tested the corrected vision should be tested in the same manner.

If a contact lens wearer cannot remove his/her lenses at the initial examination, he/she should be required to return. It is not necessary to repeat examination to remove the contact lenses.

In initial applicants if the uncorrected vision is 6/60 or less the refractive error must be recorded in the space provided.

Be sure to note whether contact lenses were worn during the examination and whether you recommend an eye specialist's examination.

Figure 3 - Vision Standards

Distant Vision	In each eye separately, equal or better than
Category 1	6/9 (20/30) Corrected or uncorrected in each eye. 6/6 (20/20) both eyes
Category 2	Same as Category 1.
Category 3	6/9 (20/30) or 6/12 (20/40) Corrected or uncorrected. No less than 6/60 (20/200) uncorrected.
Category 4	No less than 6/9 (20/30) in the better eye.
Near Vision
Categories 1, 2 and 3	N5 at 30 - 50 cm.
Category 4	No standard.
Ocular Muscle Balance
Categories 1, 2 and 3	Exophoria and Esophoria: maximum 6 prism dioptres. Hyperphoria: 1 prism dioptre.
Category 4	No standard.
N.B. Vision Testing machines such as the Titmus Vision Tester, Keystone Orthoscope or Telebinocular, Bausch & Lomb Orthorator may be used.

Near Vision

Near vision should be tested with the Faculty of Ophthalmologists Reading Type 'N' charts or equivalent. Vision in each eye separately should be tested without and then with correction. Use good "over the shoulder" illumination of the card and avoid reflections and glare. Note that the standard does not require the near vision correction to meet TC Standards in each eye separately.

Ocular Muscle Balance

Ocular muscle balance can be tested with the cover test, the Maddox rod or an approved vision tester. Report the results of the cover test in the space provided. The Maddox rod results should be noted in the appropriate spaces. Checking the orthophoria box means that there is no deviation and the other spaces can be left blank. Any deviations should be noted in the esophoria, exophoria and hyper phoria boxes.

Maddox Rod Test - This is described in detail in Appendix 1 and on the aviation vision video. The results should be recorded in the number of dioptres of esophoria, etc. The use of this instrument is demonstrated in the video "The Vision Examination for Aviation Medical Examiners"

If the candidate is orthophoric no movement of the eyes will take place. If there is esophoria one eye will move in and then re-fixate when the occluder is removed. In exophoria the opposite is true. It should be noted that less than 10% of individuals are orthophoric!

Colour Perception

Colour perception should be tested at each aviation medical examination because various eye diseases may cause a change or deterioration. Colour vision may be tested with any of the standard pseudoisochromatic test plate sets noted in Appendix 2. Appropriate lighting must be provided for testing. If a special colour balanced light source is not used, daylight is best for screening. Be wary of fluorescent or incandescent lights which may cause inaccurate readings. The type of plates (Pseudo-isochromatic, Ishihara etc.), the number of plates in the set (versus the number that should be used for testing) and the number of errors should be noted.

Note: The colour lantern test is not acceptable for initial air traffic controller applicants, who must pass the plates or a Farnsworth D-15 Hue test.

Hearing Examination

This should be tested with the whispered voice. The applicant must be able to hear and understand at a distance greater than 2 metres. Testing with screening audioscope is acceptable. Abnormalities noted on the screening test should prompt testing by pure tone audiometry. Candidates for Category 1 or 2 medical certification will require a pure tone audiogram at the initial examination.

Urinalysis

Routine dip-stick testing of the urine for glucose is required at each aviation medical examination. Microscopic examination is only required where clinically indicated.

Other tests

Self-explanatory.

Renewing a Medical Certificate

If an applicant who has a licence meets all the medical standards in CAR 424 you may renew his/her Medical Certificate (MC) by stamping, signing and dating one of the renewal boxes on the MC. Return the 'renewed' MC to the applicant and mark the FIT box on the MER form. You cannot grant additional privileges. For example, if an applicant with a restriction such as "Valid only when wearing required glasses" presents for medical certification with contact lenses, you can only extend the present privileges, not give authorization for him/her to use contact lenses when flying. This must be done by CAM. In the same way you cannot give authorization for an upgrade from one medical category to another.

Initial applicants do not have a MC so you cannot grant them a medical category and can only mark the DEFERRED box, indicating "initial applicant" under the remarks area.

If an applicant does not present a MC for signature you cannot renew, but only mark DEFER and indicate "no MC available" under the remarks area.

Figure 4 - Medical Certificate

Figure 4 - Medical Certificate

If you feel that the applicant is fit, make sure that you put the date of renewal on the renewal box as this relates to the validity period - An undated renewal makes the MC invalid!

Special Renewal

A small number of licensed personnel will have been issued with a MC that has been endorsed over the renewal boxes "Not valid for CAME renewal".

In these cases, send in the medical examination report and any other reports/tests that have been requested. Mark the "depressed" box in Part "D". The applicant will be issued with a new MC at each examination.

Appendix 1

The Maddox Rod Test

This test is used to uncover latent squints (phorias). The test may be performed with a handframe, a vision tester or a trial frame but the principle in all is the same. If a candidate is given two dissimilar targets to view at the same time, the stimulus to fusion is absent and phorias are uncovered.

The Maddox rod is a disc of red glass in which are molded grooves. When a distant spot of light is viewed with the disc in front of one eye, a red line will be seen by the eye covered with the lens, whilst a spot of light will be seen with the other eye. The line will be at right angles to the grooves to that when these are horizontal the line will appear vertical. A candidate with no latent deviation will see the coloured line pass through the spot of light (orthophoria), whereas a candidate with latent squint will see the light source to one side of the line.

The Maddox rod with rotating prism is held in front of the right eye and the candidate is asked to look at a point source of light 6m (20 ft.) away in a darkened room. Both eyes must be open and squinting should be avoided. The candidate is asked which side of the line the dot is seen. If it is to his right, esophoria is present and if to the left, exophoria. The candidate is then asked to "put the line on the light" by adjusting the rotating prism. The examiner reads off the degree of phoria from the scale on the device.

The test is repeated with the disc turned to the vertical position. The light will now be seen either above or below the line and may be adjusted by the candidate in the same way. If the red line is above the light there is left hyperphoria, if below the light, right hyperphoria.

If the candidate sees several lines, there are aberrant light sources and, if they cannot be suppressed, the correct line can be indicated by turning the spot light on and off several times. Some candidates are aware that the line should pass through the spot and may try to hide their phorias. This should be suspected if a candidate with an abnormal cover test sees the line directly through the light. In this case the lens can be adjusted so the dot and the line do not coincide and the candidate's response should be noted.

Definitions

Orthophoria - No tendency to deviate.

Esophoria - Tendency of the eye to turn in.

Exophoria - Tendency of the eye to turn out.

Hyperphoria - Tendency of one eye to turn up or the other eye to turn down.

Demonstrations of the Maddox rod Test may be seen on the video The Vision Examination for Aviation Medical Examiners.

Appendix 2

Colour Vision

In the retina there are two groups of photosensitive cells, the rods and the cones. The cones, concentrated in the central retina, are colour sensitive. They contain three different pigments. One is sensitive to red, another to green and a third to blue. Congenital colour deficiencies are caused either by the absence of one of the pigments or by an alteration in the pigment which leads to distortion of colours. People lacking or deficient in the red pigment are known as Protans, the green pigment Deutans and the blue pigment Tritans. The latter problem is unimportant and unusual.

Normal people are trichromats. Those who have only two pigments are dichromats and, according to the missing pigment, are referred to as protanopes, deuteranopes and tritanopes. There are also groups of trichromats whose pigments, although present, are anomalous. According to the pigment therefore they are protanomalous, deuteranomalous or tritanomalous (trichromats). Approximately 8.5% of the male population and 0.4% of the female population have colour vision defects. About 4.6% of all males are deuteranomalous trichromats and the other 3.4% are evenly distributed amongst the protanomalous trichromats, deuteranopes and protanopes with a frequency of about 1% each.

Pseudoisochromatic plate tests differentiate between people with normal colour vision and those with defective colour vision of types which might interfere with aviation safety. These plates should be viewed by the applicant in natural daylight. The applicant should not be allowed to wear sunglasses or "XChrom" lenses. Each plate should be held approximately 75 cm. in front of the applicant with the plate perpendicular to the visual line. A delay of up to three seconds is allowed for the answer to each plate and it is permissible to repeat a plate if the patient has a negative response. If two responses are given, the second should be recorded. The plates should be given in a random order so they cannot be memorized. The number of acceptable incorrect responses to each type of plate is shown below. Colour vision testing should be carried out from time to time as it also varies in eye diseases and may be an
early method of detecting such problems.

Applicants who fail the plates may be tested with a colour vision lantern. Anumber of these are available in each region and information is available through the RAMO's office. The Farnsworth D-15 Hue test is also acceptable.

Note: The colour lantern test is not acceptable for initial air traffic controller applicants, who must pass the plates or a Farnsworth D-15 Hue test.

Type	Edition	Tested	Errors Allowed
American Optical (1965 Ed.)	18	1-18	3
American Optical HRR	20	1-6	0
Ishihara	16	1-8	1
Ishihara	24	1-15	2
Ishihara	38	1-21	3
Ishihara (concise)	14	1-14	Special explanation with plates
Keystone Orthoscope ®		All	0
Keystone Telebinocular ®		All	0
Titmus		All	0

Section 2

The Atmosphere

The earth's atmosphere surrounds it like a gaseous blanket, kept in place by the gravitational field. The depth of the atmosphere varies from time to time, being greater in the summer than in the winter and greater at the lower latitudes than at the higher latitudes. Heat radiating from the sun causes atmospheric gases to expand into space and it is the interaction between this force and gravity that sets the limits of the atmosphere.

Composition

The atmosphere is a mixture of various gases. The three of greatest importance are Nitrogen (78.09%), Oxygen (20.95%) and Carbon Dioxide (0.03%). The remainder is made up of rare gases. The composition of the atmosphere is remarkably constant up to approximately 300,000 feet although at high altitudes the distance between gas molecules becomes progressively greater and collisions between particles becomes rarer. There is a variable amount of water vapour in the atmosphere up to about 30,000 ft. and in the lower altitudes there are also solid pollutants which provide nuclei for condensation.

Divisions

We live in the troposphere which means "the area of change". In the troposphere the temperature decreases with increasing altitude at a rate of 1.98°C or 3°F/1000 ft. The troposphere extends up to 60,000 ft. over the equator but only to about 30,000 ft. over the poles. At that altitude it becomes the tropopause where the air temperature is fairly constant between - 50 and -55°C. Above the tropopause, which is about 30,000 ft. deep, is the stratosphere which extends to about 50 miles (80 kms.). There is no weather in the stratosphere and indeed there is little weather above 35,000 ft. One of the joys of flying is that on the dullest day one can break out into bright sunlight if you climb high enough.

Ozone

Within the stratosphere lies the ozonosphere at 18-30 miles (30-50 km.) above the earth. The temperature here becomes warmer (about 35°C) due to heat released when ozone is converted to oxygen by solar radiation. Only in the last decade has the importance of the ozone layer become apparent to us all. In the stratosphere oxygen absorbs ultraviolet (UV) radiation of 2,000 Å. And 3 molecules of oxygen are transformed into 2 molecules of ozone. If unchecked this reaction would produce a huge amount of ozone, however ozone in turn absorbs ultraviolet light from 2,100 to 2,900 Å. and is converted back to oxygen. This balanced reaction results in the almost total absorption of harmful ultraviolet radiation. Recently it has been found that the ozone layer is being destroyed, particularly over the poles, by earth's pollutants. This may give rise to the increasing penetration of UV light causing an increase in skin cancer, cataracts and other health problems.

Ozone is a blue, unstable, toxic gas. The concentration at ground level is 0.03 parts per million (ppm) by volume but this increases rapidly above 40,000 ft. to become a maximum of 10 parts per million by volume at 100,000 ft. Modern supersonic aircraft fly at altitudes where this can be a problem. In the human, acute exposure for two hours to between 0.6 and 0.8 ppm. reduces the diffusing capacity of the lungs and slightly reduces vital capacity and forced expiratory volume. Fortunately these effects are not permanent unless there is continual exposure. Ozone impairs night vision in man and in human cell cultures can induce chromatic breakages identical to those produced by x-rays. Fortunately ozone is thermally unstable and is decomposed promptly to oxygen at 400°C. This temperature is reached by the Concorde's air conditioning compressor circuit during climb and cruise, neutralizing what could otherwise be a significant problem.

Atmospheric Pressure

Atmospheric pressure is the weight of the gases surrounding the earth. It is a function of height, density and the force of gravity. At ground level it is recorded by meteorologists as 101.32 kilopascals but many people prefer the older 14.7 lbs. per sq. inch or, as used in most medical calculations, 760 mmHg. Atmospheric pressure decreases with altitude and at 18,000 ft. it is halved (380 mmHg) and at 33,000 ft. quartered. It should be noted that the changes are small and gradual compared to the changes observed going down in water. Here atmospheric pressure doubles at 33 ft! As will be noted later this is a point of importance when dealing with fliers who are also scuba divers.

Figure 5 - Properties of the Standard Atmosphere

The properties of the standard atmosphere showing the variation in the height of the tropopause.

Figure 5 - Properties of the Standard Atmosphere

Cosmic Radiation

The atmosphere is affected by both galactic and solar ionizing radiation. The former is a predictable, low density flux of high energy particles from outside the solar system. Most of these are deflected by the earth's magnetic field although the protection is greater in the equatorial regions than at the poles. There is also some protection by the solar interplanetary magnetic field and by the stratospheric absorption of low energy particles. Measurements of this type of radiation have been taken from high altitude aircraft. Fortunately the annual dose is relatively low in constantly exposed air crew.

Solar radiation is of lower energy but its production may be intense and is generally unpredictable although it appears to reach a peak about every 11 years. The earth is well shielded by its atmosphere but the dose may be significant in prolonged high altitude or space flight. It's most commonly observed effect is interference with radio and other forms of communication equipment at the time of solar flares. Space flight will lead to more precise measurements of its long term effects.

Hypoxia and Hyperventilation

The hazards of high altitude became evident as soon as men set out in balloons, although the dangers had been suspected by missionaries in mountainous areas long before. In 1590 the Jesuit Priest Acosta noted "... I am convinced that the element of the air is in this place so thin and so delicate that it is not proportioned to human breathing which requires extensive and more temperate air".

In 1862 Glaisher and Coxwell made an ascent by balloon to almost 29,000 ft. and became unconscious. Fortunately one of them, his hands frozen, was able to raise his head sufficiently to grab the valve cord of the balloon in his teeth before passing out, thus releasing hydrogen and bringing the balloon back down. Paul Bert in the late 1860's built an altitude chamber and reached the conclusion that, regardless of barometric pressure, air could not supply life when the partial pressure of oxygen reached 45 mm. Hg. In April of 1875 Crocé-Spinelli, Sivel and Tissandier made the first flight in a balloon using oxygen although Bert had warned them the supply was far too small. Only one of the three survived, the other two dying of hypoxia.

Respiratory Physiology

To maintain life, oxygen has to be inhaled, diffused across the alveolar-capillary membrane, carried by hemoglobin to the tissues and then transferred to the individual cells for aerobic metabolism. Dalton's Law states that the partial pressure of a gas in a gas mixture is equal to the pressure which the gas would exert if it alone occupied the space taken up by the mixture. Each of the gas components in the mixture therefore exerts pressure proportional to the fraction which it represents. Oxygen, being present as 20.9%, (21%) of the gases in our atmosphere exerts a partial pressure of 160 mm. Hg in dry air at sea level. However this changes when it is inspired. In the nasopharynx air is exposed to water vapor and becomes saturated at body temperature (37°C). Water vapour pressure is 47 mm. Hg. In the trachea therefore the partial pressure of oxygen will be (760 - 47) x 0.21 or approximately 150 mm. Hg. Passing from the trachea to the alveolus, oxygen becomes mixed with carbon dioxide. It is also diffusing into the tissues from the respiratory bronchioles down, so by the time the alveolus is reached, the partial pressure of oxygen is much lower. The partial pressure of carbon dioxide is about 40 mm. Hg so the alveolar partial pressure of oxygen at ground level, when the respiratory quotient is taken into account, is 103 mm. Hg (For those mathematically inclined relevant formulas are given at the end of this chapter). This steadily dropping partial pressure is known as the respiratory cascade.

The diffusion of oxygen (and of carbon dioxide in the opposite direction) takes place at the level of the respiratory bronchioles and below. The majority of the diffusion takes place at the alveolus which is virtually surrounded by capillary blood. The area of the alveolar-capillary interface is astonishingly large, between 90 and 100 sq. metres. If spread out the alveoli would cover a double tennis court. Diffusion at the alveolus takes place along the pressure gradient with most of the oxygen being picked up by hemoglobin for transfer to the tissues. The rate of diffusion of a gas is proportional to its solubility and to the pressure gradient. Carbon dioxide, being more soluble than oxygen, diffuses at a faster rate. In the tissues the pressure of oxygen falls with increasing distance from the capillary, with the lowest level being found midway between two capillaries. If the partial pressure of oxygen falls below 3 mm. Hg in the tissues anaerobic metabolism develops. Under normal conditions a rise in PC02 and the formation of tissue lactic acid causes capillaries to dilate. In muscle the number of open capillaries can increase by 200 times but in the brain most of the capillaries are open, even at rest, so even in the face of imminent hypoxia the number of cerebral capillaries can increase only by a factor of four. This is why hypoxia affects the brain first.

Hemoglobin Dissociation

Oxy-hemoglobin (Hb02) dissociation describes an S-shaped curve (See Figure 6) when saturation is plotted against oxygen partial pressures. The characteristics of this curve are important. Down to a partial pressure of 60 mm., saturation remains above 90%. Below this point saturation drops off rapidly being less than 80% by the time the partial pressure has dropped to 45 mm. The sharp drop-off of the curve enables oxy-hemoglobin to unload rapidly in the relatively hypoxic tissues and equally allows reduced Hb to pick up oxygen rapidly at normal diffusion gradients. Under hypoxic conditions lactic acid is formed in the tissues causing a relative acidosis which moves the curve to the right, increasing the uptake and release of oxygen. In alkalosis, as in hyperventilation, the curve moves left, lessening tissue availability. (Fig.6)

At 10,000 ft. the PAO2 has reached 60 mm., which is the beginning of the rapid drop in hemoglobin saturation. Above this altitude significant tissue hypoxia develops and it is for this reason that oxygen is required while flying above 10,000 ft. If the pilot is breathing 100% oxygen however the partial pressure of oxygen at any level will be much higher. The critical level of 60 mm. at the alveolus for example will not be reached until 40,000 ft. This is referred to as an "equivalent oxygen level".

Figure 6

Figure 6 - Oxyhemoglobin Dissociation Curves for Human Blood

Hypoxia

Hypoxia is an insidious killer. There is a tendency for euphoria to develop while motor skills and reasoning abilities deteriorate. The result is that in many cases the pilot may become seriously hypoxic without appreciating that there is a problem. To the observer tachypnea, cyanosis, mental confusion and loss of muscle coordination are obvious. To the pilot however, the only symptoms may be slight dyspnea, dizziness, fatigue, decreasing vision and finally loss of muscular control. Night vision can be impaired at as low as 5000 ft. Tolerance to hypoxia varies from individual to individual and from time to time. Tolerance can be increased by continual exposure to high altitudes and varies with the level of the hemoglobin and the oxygen carrying capacity of the blood. It is decreased by fatigue, cold and poor physical conditioning. Even at 5,000 ft. night vision is decreased.

Types

Hypoxia is generally divided into four types.

Hypoxic hypoxia is due to a decrease in the oxygen available to the body such as typically occurs with altitude.

Hypemic hypoxia is caused by a reduction in the oxygen carrying capacity of the blood for any reason. It also occurs when hemoglobin is saturated by gases for which it has a higher affinity, the most common of which is carbon monoxide. This is not only produced by exhaust leaks into the cockpit but also by cigarette smoking. Carbon monoxide is a product of incomplete combustion and may be present at levels of 6-8% in the blood of a heavy smoker and such individuals may become significantly hypoxic at levels below 10,000 ft.

Stagnant hypoxia is a less common problem caused by a reduction in total cardiac output, pooling of the blood or restriction of blood flow. Heart failure, shock, continuous positive pressure breathing and Gforces in flight can create stagnant hypoxia. Local stagnant hypoxia can occur with tight and restrictive clothing or, in the cerebral circulation, in association with vasoconstriction due to respiratory alkalosis provoked by hyperventilation.

Histotoxic hypoxia refers to poisoning of the respiratory cytochrome system by chemicals such as cyanide or carbon monoxide but it can also be caused by the effects of alcohol. Needless to say a pilot in poor physical condition, recovering from a hangover and smoking while in flight can quickly become an unfortunate statistic!

Gravity and Atelectasis

In the seated position the lungs, due to the pull of gravity, are stretched at the apices and condensed at the bases. At the same time, the blood supply is least at the apices and greatest at the bases. Thus in the area where the alveolar ventilation is best, perfusion is least and at the bases the opposite is true. Only in the mid section of the lung is there an ideal ventilation - perfusion ratio. Under positive G, the situation is exaggerated and if it is of long duration in crews breathing oxygen, rapid absorption from the alveoli tends to cause basilar atelectasis.

Hyperventilation

Hyperventilation may be described as a respiratory rate excessive for the body's oxygen requirements. It may be voluntary or involuntary and can occur in relation to many different activities. In the pilot the most common precipitating causes are anxiety, fear, excessive concentration on a flight procedure and as a reaction to pain or illness. Hyperventilation may be obvious, as in the case of children preparing to compete in underwater swimming, or it may be covert as for example when the respiratory rate increases from a required 12 per minute to an excessive 15 per minute and remains elevated for a prolonged time.

Whatever the cause the results are the same. Carbon dioxide, the most potent stimulus to respiration, is blown off in excessive amounts. The PACO2 falls and respiratory alkalosis develops. The cerebral vessels become constricted and subjectively the pilot often notices a feeling of dizziness, a coldness and tingling around the lips and a feeling as though there was a band around the head. Nausea may be present. Peripherally there is vasodilatation and stimulation of sensory nerves causing a sensation of pins and needles in the hands and in the feet. If hyperventilation continues carpopedal spasm develops and the subject may become unconscious and develop frank tetany. With the breath held the carbon dioxide levels build up once more and the symptoms disappear in reverse order.

Obviously such a chain of events can lead to an accident. This has been documented in some incidents in young fighter pilots or untrained private pilots who have inadvertently flown into bad weather and have kept the microphone button depressed, broadcasting their breath patterns up to their final moment. Hyperventilation is often suspected in unexplained accidents. If one considers the symptoms of hypoxia and hyperventilation it will be seen that they are very similar. As it is imperative in the air that no mistake be made, the treatment for both is to breathe 100% oxygen and to reduce the rate and depth of respiration.

Pressurization and Depressurization

Although it is usually in military pilots that problems arise with hypoxia at levels above 30,000 ft., it must be remembered that more and more commercial aircraft are now cruising at extreme altitudes and flight above 40,000 ft. is common. The Concorde, for example, cruises above 60,000 ft. Cabin pressurization in these aircraft ensures that the partial pressure of oxygen is adequate and it is rare for the cabin pressure to be above 7,000 ft. (See Fig. 7). However, it is wise to remember that passengers with chronic lung diseases or serious anemia, particularly those who are smokers, may be significantly hypoxic even at this altitude.

Figure 7 - Cabin Pressurization

Ambient Altitude in feet	Cessna 152	Boeing 727	Boeing 777	Boeing 747
80,000 40,000 35,000 22,500 15,000 SL	- - - - 15,000 SL	- - 5,500 SL SL SL	- 6,500 4,500 SL SL SL	- 7,700 4,700 SL SL SL
SL = Sea Level

More dangerous however is the situation which develops when cabin pressure suddenly fails, usually due to the loss of a window or door. The result is rapid decompression with a sudden increase in the cabin altitude to match the ambient altitude. In aircraft such as the Concorde the windows have been made particularly small to lessen this effect but in older aircraft more serious problems have occurred. The immediate effect of decompression is a loud noise, condensation of water vapour causing a mist and a shower of dust and small particles. The temperature falls dramatically. The resultant cabin pressure may actually fall below that of the ambient pressure due to "aerodynamic suck". This refers to the Venturi effect created by the speed of the aircraft through the air.

The initial hazard to aircraft safety is hypoxia. The crew are unlikely to be wearing oxygen masks at the time of the incident and, if the final cabin altitude is high, the time of useful consciousness may be very short (see Figure 8). It may actually be lower than would be anticipated because of the sudden escape of expanding gas from the lungs due to the reduced ambient pressure. This causes reversal of the oxygen diffusion gradient across the alveolar membrane and oxygen passes back into the lung from the blood. At 35,000 ft. the time of useful consciousness is generally quoted as 30 - 60 seconds but at altitudes of above 40,000 ft. this may be reduced to 12 - 15 seconds, the normal circulation time. Airlines make provision for this eventually by providing pilots with "quick-donning" oxygen masks, which can be donned in 5 seconds or less.

Figure 8 - Times of Useful Consciousness
(Effective performance time)

Altitude	Conscious time
20,000 25,000 30,000 35,000 40,000 45,000 50,000+	5 - 12 minutes 2 - 3 minutes 45 - 75 seconds 30 - 60 seconds 10 - 30 seconds 12 - 15 seconds 12 or less seconds

For Those of Mathematical Bent

In Dry Air:

PIO2 = AP x FIO2 where PIO2 is the partial pressure of oxygen, AP is atmospheric pressure and FIO2 is the fraction of oxygen in the inspired air.

In the Trachea:

PIO2 = (AP - WVP) x FIO2 where WVP is water vapour pressure. At sea level this is (760 - 47) x 0.21 = 150 mmHg.

In the Alveolus:

PAO2= PIO2 - PAC O2 [FIO2+ (1 - FIO2/R)] where PACO2 is the partial pressure of carbon dioxide and R is the respiratory quotient.

Therefore at sea level PAO2 = 150 - 40 [0.21 + (1 - 0.21/0.82)] = 103 mmHg.

Or at 18,000 ft. = (380 - 47) x 0.21 - 30 (0.21 + 1 - 0.21/0.82) = 35 mmHg.

The respiratory quotient (R) on a pure carbohydrate diet is 1.00, on a protein diet 0.81 and on an animal fat diet 0.71. On a balanced diet of carbohydrate, protein and fat, R is generally about 0.83.

Dysbarisms and Altitude Sickness

We have already commented on the decrease in atmospheric pressure which occurs with altitude. Boyle's Law states that, at constant temperature, the volume of a gas varies inversely with the pressure. If the pressure of gas is halved, its volume is doubled. Application of this simple law to the closed body cavities quickly indicates where problems are likely to occur.

Barotitis

By far the most common problems are with the middle ear. It resembles a box, closed by a flexible diaphram at one end and drained by the Eustachian tube narrow tube at the other. The eustachian tube however is not rigid or symmetrical throughout its length and becomes slit-like at its outlet in the nasopharnyx. On ascent expanding trapped air usually escapes easily and the only thing noticed is a periodic "popping" due to movements of the drum as pressure equalizes. On descent however equalization of pressure through the slit-like outlet is much more difficult and a negative pressure can build up in the middle ear. This leads to a decrease in hearing and to pain. The ear can be cleared by opening and closing the mouth, thus activating the tensor tympani muscle and dilating the tube, or by inflation by a Valsalva maneuver. In an U.R.I. or other pathology of the nasopharynx, congestion of the outlet makes clearing more difficult or even impossible. The pressure in the middle ear on descent may then become so low relative to the outside pressure that exudation and hemorrhage may take place and ultimately the eardrum may burst. Excessive valsalva maneuvers however may force bacteria into the middle ear, leading to infection.

When an ear blocks and cannot be cleared by the usual maneuvers, the best way to deal with the situation is to reascend and start a slower descent. This is not always possible. During World War II the pilots of vertical diving Stukas had constant ear problems and their flight surgeons solved these by periodically incising the drums! Nowadays this is not recommended! A particular problem occurs when pilots flying at high altitude on oxygen retire to sleep soon after landing. The middle ear is full of soluble oxygen (rather than inert introgen) which is absorbed during sleep. On awakening they have earache due to the indrawn drums. This is called "oxygen ear".

Other Barotraumas

Other air spaces are equally affected. The nasal sinuses are a common source of pain as may be poorly filled teeth if the filling has not been carefully inserted and a gas space remains below it. These various symptoms are referred to as "barotraumas" and toothache of this type is known as "barodontalgia". The best approach to these conditions is knowledge and prevention. Fortunately most professional pilots are well aware of the problems and avoid flying when they are congested.

Intestinal Gas

A common irritating, embarrassing and potentially serious problem is gas in the bowel. This expands rapidly as might be expected and, if it cannot be passed, may lead to severe pain. Chewing gum, air swallowing, carbonated drinks and beer (in the passenger) all add to the gas, as do various gas producing foods. Passengers with ostomy bags or various types of bowel obstruction are particularly likely to have problems.

Inflatable Medical Aids

Boyle's Law must be kept in mind if you are involved in the transport by air of patients requiring cuffed tubes of any type or if casts or pneumatic dressings are being used. Cuffs should be inflated with saline (or water) rather than air before the trip.

Decompression Sickness

The "Bends" or "Caisson disease" has been recognized since 1841 in association with "hard hat" divers or men working under pressurized conditions. By the end of WWI the possibility of decompression sickness in aviators was predicted and once high altitude balloon flights were undertaken the prediction was fulfilled. The cause of decompression sickness is the formation of gas bubbles in the body and the physical law was described by Henry. Henry's Law states that the quantity of gas that goes into solution at a given temperature is dependent upon its solubility characteristics and is proportional to the partial pressure of that gas over the surface of the liquid. Hence as the pressure falls, the amount of gas which can be held in solution is reduced.

Bubble Formation

The dominant gas in the atmosphere we breathe is nitrogen. It is inert and the body is saturated with it at ground level. During rapid ascent the reduction of barometric pressure creates a condition whereby the inert gas tension in the tissues is greater than the external barometric pressure. This condition is called super-saturation. At this point, in association with bubble nuclei produced by muscle shear forces or turbulent blood flow, bubbles of nitrogen can be formed in the tissues and in the body fluids. It is these bubbles which give rise to decompression sickness.

Symptoms

The symptoms of decompression sickness are described as the four "C's". These are Creeps, Cramps, Chokes and Collapse". "Creeps" is an unpleasant sensation as though tiny insects are moving underneath the skin. This "formication" is believed to be caused by the formation of tiny bubbles. "Cramps", usually described as "Bends", are manifested by pain which tends to be localized in and around the large joints of the body. Smaller joints may be affected and it is not uncommon to first notice the symptoms in joints which have previously been injured. The pain is deep and aching in character and varies from mild to severe. It is made worse by movement of the joints and is sometimes improved by pressure on the area. "Chokes" are rare, occurring in less than 2% of cases. It is a much more serious disorder caused by multiple pulmonary gas emboli. The subject complains of substernal chest pain, dyspnea and a dry, non-productive cough. He/she feels ill and usually appears anxious and distressed. If altitude is maintained "Collapse" will inevitably occur. The treatment is immediate descent which is generally effective.

Neurological Effects

Neurological decompression sickness is the most dangerous form and often has a very serious prognosis. It may be responsible for permanent neurological deficits particularly if hyperbaric treatment is not immediately available. It occurs in 5- 7% of cases of decompression sickness, and, in altitude cases not relieved by returning to ground level, the central nervous system is involved 35-50% of the time. In the aviator brain injuries, although uncommon, are most frequent. In divers the spinal cord type is most frequent. The reason for this variance is not known.

In the brain type visual disturbances (scotoma, tunnel vision, diplopia etc.) are common together with headache and confusion. Physical signs are spotty and diffuse, both motor and sensory. The signs may be thought to be hysterical but collapse may occur. In the spinal cord the most common onset is of numbness or paraesthesia in the feet. This tends to spread upwards in the cord with ascending weakness and/or paralysis. A complete transverse spinal cord lesion may occur as bubbles obstruct the blood supply and infarct the cord.

Fortunately serious decompression sickness is uncommon in commercial aviation. Generally the altitude threshold is above 18,000 ft. although it rarely occurs below 25,000 ft. Above 26,000 ft. it is more common. It is much more often seen therefore in high altitude military pilots whose cockpit pressurization profiles are lower than those in commercial aircraft.

Provocative Factors

There are various factors which affect it. The incidence increases with age, there being a threefold increase between the 19-25 year old and the 40-45 year old age groups. Nitrogen is well dissolved in fat, so obesity is a factor. It is probably more common in women than men. It is more common with exercise at altitude, with rapid ascents, with re-exposure to altitude at frequent intervals and at low temperatures. The after effects of alcohol and intercurrent infection both increase the susceptibility.

Scuba Diving

It is important to keep in mind the relationship between SCUBA diving and decompression sickness in aviators. SCUBA divers use compressed air in their tanks and are often exposed to two or more atmospheres of pressure, supersaturating the tissues. If they fly within twelve hours of emerging from diving at standard depths, decompression sickness has been recorded at altitudes as low as 10,000 ft. Where they have been diving at depths which require decompression stops on the way to the surface, they should not fly for a minimum of 48 hours. Although serious problems are uncommon, it is necessary to be aware of the danger to recognize it, particularly with neurological symptoms.

Occasionally a medical emergency results when a diver ascends to the surface too rapidly, causing a bubble formation. In such cases the diver must be reexposed to a greater pressure as quickly as possible and then brought back to the surface. Sometimes the diver is too ill to undertake another dive and must be transported to a hyperbaric chamber for treatment as quickly as possible. Pilots transporting such individuals should be cautioned that increases in altitude will worsen the patient's condition. If pressurized aircraft are not available, flights should be made at the lowest safe altitude. Recompression treatment tables are outlined in textbooks of Diving medicine.

Acceleration

Doctors often feel that an understanding of acceleration (G) and the effects of gravity (g) are only of importance to aerobatic or high performance aircraft pilots. This is a mistake. Because we are normally terrestrial creatures, bonding to the earth has taught us that gravity exerts a downward pull. In an aircraft however, G-forces are often upward or outward and as they are associated with changes in both acceleration and direction, what is experienced is a resultant force. It is these forces and their effects on the vestibular organs which give rise to our recognition of position in space. In the review of orientation the importance of this will be explained.

G Axes

Speed is the rate of movement of a body while velocity is a vectorial quantity made up of both speed and direction. Acceleration (G) is a change in velocity either in direction or in magnitude. It is described in three axes in relation to the body, x, y and z. Each axis is described as positive (+) or negative (-) according to an international convention.
Considerable confusion can arise if a clear distinction is not made between the applied acceleration and the resultant inertial force as these, by definition, always act in diametrically opposite directions. Thus a headward acceleration tends to displace tissues such as viscera and the eyes, footward and the resultant force is termed positive G, +Gz. (See Fig. 9).

Physiological Effects

The physiological effects of G vary with its magnitude, duration and axis of application and are modified by the area over which it is applied and the site. Tolerance to acceleration varies from day to day and is modified by body build, muscular tone and experience. It is decreased by poor health or conditioning, fatigue, hypoxia and alcohol. It can be increased by continued exposure and education. Pilots exposed to heavy G loads soon learn to use a modified Valsalva manoeuvre with controlled breathing and muscle contraction to increase their tolerance (the M1 manoeuvre). G-suits mechanically increase resistance to positive Gz by exerting pressure on the lower limbs and the abdomen to prevent pooling of blood. Unfortunately there is no mechanical device to counteract negative Gz.

Figure 9

Direction of Acceleration	Direction of Resultant	Physiological and Vernacular	Standard Terminology Descriptors
Headward	Head to Foot	Positive G Eyeballs down	+Gz
Footward	Foot to Head	Negative G Eyeballs up	-Gz
Forward	Chest to Back	Transverse A-PG Supine G Eyeballs in	+Gx
Backward	Back to Chest	Transverse P-AG Prone G Eyeballs out	-Gx
To the Right	Right to Left side	Left lateral G Eyeballs left	+Gy
To the Left	Left to Right side	Right lateral G Eyeballs right	-Gy

Positive Gz

Positive Gz forces the pilot into the seat, draining the blood towards the lower part of the body. A 150 lb. pilot exposed to +4G has a weight equivalent to 600 lbs. This interferes with muscular movement, aircraft control and the ability to change position or to escape in an emergency. As G comes on and blood is drained from the head, the first symptom is visual. The normal intra-optic arterial pressure is 20/25 mm. of Hg. and under loads as low as 2-3G peripheral vision is decreased due to retinal anemia. This leads to "grey-out", a condition in which peripheral vision is progressively lost and central vision begins to lose its acuity. As the G load increases the retinal arterial flow is further reduced until "black-out" occurs. At this point, although vision is absent, the cerebral blood flow is often maintained and the pilot may remain conscious. At 5-6G however most pilots become unconscious unless they are protected. This is referred to as G-LOC. (G-Loss of consciousness). When the G load is reduced, consciousness will be regained although there is often a brief period of confusion before full awareness is reached. If the G load is high and the onset is of short duration, G-LOC can occur without warning. This has been determined as the cause of several accidents in high performance aircraft.

Negative Gz and Jolt

Negative Gz, acting from the foot to the head, is poorly tolerated by the body and in most cases the threshold is below -5 Gz. As might be expected the visual symptom is "red-out" as blood is forced towards the head and into the retinal arterioles. Excessive -Gz leads to hemorrhages into the conjunctiva and ultimately into the brain.

A special form of G is known as "jolt". Jolt is the rate of change of acceleration. It is descriptively used in relation to short, sharp accelerations. This type of shock can give rise to serious spinal injuries and must be minimized in the design of ejection seats.

Brief alternating positive and negative Gz forces are experienced in turbulence and may be a serious problem when flying light aircraft in hot weather or flying high speed aircraft at low levels. G-forces not only interfere with precise flying but are also a potent source of fatigue.

Transverse and Lateral G

Tolerance to transverse G (Gx) is much higher. It is for this reason that the astronauts in the early vehicles were placed in a recumbent position during lift-off. Forces as high as +60 Gx have been experienced over short intervals without injury. However, G interferes with both lung inflation and respiratory movements and forces greater than +20 Gx quickly lead to breathing difficulties. -Gx is less well tolerated. Gy is not of great enough amplitude to cause problems in consciousness and is not a problem with modern day aircraft. It does come into account however in VTOL aircraft such as the Harrier which is able to "VIFF" (Vector in forward flight) sideways to evade attack. At present, head restraint is the only problem experienced with Gy.

Orientation and Disorientation

To the earth bound individual, orientation means being aware of one's body position relative to the earth. Gravity acts towards the centre of the earth and is recognized as down. The aviator however lives in a different world, a world in which proprioceptive senses may give rise to false information. At the top of a loop for example, where centrifugal force replaces gravity, down appears to be up and up appears to be down!

Disorientation, in the pilot's sense, (sometimes described as "vertigo") is to be unable to locate oneself in space and can be one of the most terrifying and lethal of experiences. It has been invoked as a contributory cause in 12% of general aviation accidents and in 15-20% of military accidents. We orient ourselves by vision, the vestibular system and by proprioceptive nerve data. The mental images of orientation that we derive from these impulses are learned from birth and relate to our terrestrial habitat. So strong are these sensations that it is possible to produce nausea by placing us in an environment where what we see is different to what we feel. This is the theoretical basis of motion sickness and will be described later.

Vision

Vision is the strongest orienting sense, and the one to which we turn when other senses fail. It is functionally divided into two parts. One, employing central foveal vision and sharp focus, is concerned with object recognition and is used together with learned conditioned reflexes in instrument flight. The other, ambient orientation, is peripheral, less acute and is directly connected to vestibular function. That the two parts of vision are independent can be observed in a driver who reads a map and follows the road at the same time. Although we can orient ourselves and function normally when the vestibular apparatus is absent or ablated, without vision orientation is much more difficult. However vision can also give rise to illusions both of location and of movement. How strong an impression it can give is amply demonstrated by experiencing an IMAX© movie where the camera appears to plummet the viewer through a ride on a roller coaster!

The Vestibular System

The vestibular system has three functions. It acts to stabilize vision via the oculo-vestibular reflexes, to orient the body in relation to movement in the environment and to give a perception of motion. These functions are performed by two 1.5 cm. structures imbedded in the petrous bones of the skull. Each vestibule (see Fig. 10) consists of three bony, semi-circular canals lined by tubules containing endolymph. Each canal lies in a separate plane of space: one is horizontal, one vertical and one lateral. The canals sense angular accelerations in the planes of yaw, pitch and roll respectively. They are connected at each end to the utricle, a dilated central area in which are the ampullae. In the ampullae delicate hair cells topped by a gelatinous cupola project into the endolymph and move with it like river bottom plants in a current.

The utricle is connected to the saccule and in the floor of these chambers are the macula (sacculi). The macula in the utricle lies in the horizontal plane and that in the saccule lies in the vertical plane. The maculae consist of hair cells projecting into the endolymph and covered by a gelatinous membrane containing tiny calcium carbonate crystals. They are referred to as otoliths and act as linear accelerometers.

The vestibular apparatus has connections to the visual cortex, to the innervation of the extra-ocular muscles and to the vestibular nuclei in the cerebrum. Try holding your hand up in front of your face and then moving it from side to side. The movement does not have to be fast before focused vision of the fingers is lost. Holding the hand still however and moving the head from side to side allows sharp focus to be maintained at much greater rates. Occulovestibular reflexes make this possible.

Figure 10 - View of the Right Labyrinth

Figure 10 - View of the Right Labyrinth

Proprioception

Proprioception is of only secondary importance to vision on the ground, but is much less reliable in the air. While flying, centripetal and centrifugal forces compete with gravity and proprioception may be confused. Although proprioception enables the pilot to stabilize his body in the cockpit and gives valuable clues to changing directions and attitudes in visual flying conditions, in instrument conditions "flying by the seat of the pants" can rapidly become lethal. In one experiment private pilots untrained in isntrument flying were placed in a simulator and taken from visual flying conditions into dense cloud where they were required to make a 180° turn. All crashed within 178 seconds!

Visual Illusions

These may be foveal or vectional, that is concerned with central vision or orientation vision. The former type is often associated with landing approaches and is most common where visual clues are reduced or unfamiliar. Apilot approaching an unfamiliar runway with a minor uphill slope, for example, may feel that he is too high and may fall below the normal glide slope. If the fields runs down hill, he may land long. Pilots inexperienced in the Arctic may miscalculate their height on final approach because the trees they use for unconscious reference are shorter than trees in the South. Landing in "whiteout" conditions, where the ground and horizon are obscured, or landing on a smooth, reflective lake makes judgement of height extremely difficult. Particular problems may occur at night when approaching a lighted runway in an otherwise featureless area if in the distance there is a well lit town at a higher elevation. The eye, in the absence of other clues, tends to place the two lighted areas on the same elevation which may lead to premature ground contact.

Autokinesis

There is a special problem at night with small light sources, such as stars or distant ground lights. When watched intently they will appear to move and may be mistaken for other aircraft. This movement of stationary objects is known as autokinesis and has been responsible for accidents. Where the light source is bright or large this illusion is uncommon.

Vectional Illusions

The commonest type of vectional (movement) illusion is that experienced sitting in a car at a traffic light when the adjoining car creeps forward. This causes a sensation of backward movement and often reflex braking. In the rotational plane similar illusions occur. In a darknened chamber where light from a rotating source is reflected on the walls, the movement of the light on the walls is soon replaced by a sensation of body rotation, the walls appearing fixed. Other problems are confusion between ground lights and the stars when flying over prairie areas or pilots orienting the aircraft to sloping cloud decks or to the Northern Lights rather than to the true horizon.

Vestibular Illusions

These may arise from the otoliths, the semicircular canals or from a combination of the two. They are among the most serious of the illusions and the most likely to cause lethal accidents.

At rest or in constant motion gravity is the only force acting on the otolithic membrane. We are used to interpreting gravity as a force pointing to the centre of the earth and, when our plane of movement is changed, falsely interpret sensations according to this precept. A pilot accelerating down the runway and rotating to lift-off is exposed to an acceleration which pushes him back in the seat, together with the force of gravity acting downwards. (Fig. 11).

The resultant is interpreted as a single force acting upwards and backwards. Because the brain interprets the force of gravity as being vertical, the sensation is of pitch-up and the pilot may instinctively make a forward stick movement for control. This can complicate the situation because causing negative G stimulates an oculo-vestibular reflex movement of the eyes which gives rise to the sensation that the instrument panel is moving upwards, heightening the illusion. This is the known as the oculogravic illusion. With deceleration, such as that experienced on descent when the flaps are deployed, a pitch down sensation may be felt. These sensations are normal and of no great importance if the pilot is experienced or visual flight is maintained. At night however, particularly taking off from a lighted runway into a dark featureless area, and accident can occur due to inappropriate control movements performed in the transition from visual to instrument flight. Even an experienced pilot can take as long as 7 seconds to adjust.

Figure 11

The Leans

A common form of disorientation is a sensation of incorrect rotation (or absence of rotation) caused by the semicircular canals. The cupola in its neutral position is upright. When the head rotates, the bony canals move but there is inertia in the endolymph. The cupola is therefore deflected leading to a sensation of rotation. Our sensitivity to rotation however is not perfect and can be diminished by any form of distraction. Rotation in the vertical axis of 1-3 per second may not be perceived. If a pilot, flying straight and level, gradually drops the left wing by 15 degrees whilst otherwise occupied and suddenly becomes aware from the instruments of this attitude and corrects it at a much faster rate, only the correction will be sensed. The pilot then feels as though the aircraft has rolled 15 degrees towards the right and will lean towards the left to maintain balance. This is called "the leans" and is extremely common.

Figure 12 - The Action of the Cupula During

Figure 12 - The Action of the Cupula During

Prolonged Turns

A different problem arises with prolonged turns at a constant rate, such as those encountered in a holding pattern at a busy airport. On entering a turn the cupola is deflected by the inertia of the endolymph (see Fig. 12). As the turn continues the endolymph will begin to move until it is in equilibrium with the bony canal and at this point the cupola will return to its central position. (Depending on the steepness of the turn this may occur in 10-30 seconds). When the turn is terminated the bony canal will cease to rotate immediately but the endolymph, due to inertia, will continue to swirl thus moving the cupola in the opposite direction. This gives rise to the impression that a turn in the opposite direction has been entered and the tendency will be to correct this and so to reenter the original turn.

The Graveyard Spiral

Although this is a minor distraction under most circumstances, in instrument meterological conditions it can be extremely serious and lead to a "graveyard spiral". Here the inexperienced pilot, having inadvertently entered a steep descending turn under instrument conditions, makes the correct stick movements to control the aircraft but experiencing the sensation of entering a turn in the other direction may re-enter the spiral. As the aircraft is also descending, pulling back on the stick to stop the loss of altitude, although giving rise to a comforting feeling of gravitational pull in the seat, actually steepens the spiral, ultimately driving the aircraft into the ground.

The Coreolis Phenomenon

The most extreme form of vestibular disorientation is due to the Coreolis phenomenon. This is thought to be caused when two different semi-circular canals are stimulated at the same time. As an example, a pilot taking off from an airport in instrument conditions, banks towards the left while climbing. So far there is stimulation of the otolith and of one canal. In order to reach a switch or see a gauge however the pilot turns the head quickly downwards and towards the right. Two different canals have now been stimulated and, as all are connected, a movement of endolymph takes place in the third canal. The result is a sensation of tumbling which may be extreme and worsened by visual problems due to oculo-vestibular reflexes. Even if control of the aircraft can be maintained under these very trying circumstances, the pilot may still be subject to the leans or other abnormal sensations until able to obtain a visual reference.

Types of Illusions

Distinction is sometimes made between two different type of disorientation. Type I is unrecognized and Type II recognized. Obviously a Type I illusion is more likely to lead to an accident or incident. Illusions are also divided into oculo-gyral (somatogyral) or oculogravic (somato-gravic). An oculogyral illusion is defined as the apparent movement of an object in the visual field resulting from stimulation of the semi-circular canals by angular acceleration. An oculo-gravic illusion is the false perception of tilt induced by stimulation of the otolith by linear accelerations. The terms somato-gyral and somatogravic refer to the resulting body sensations.

Motion Sickness

The relationship between this condition and orientation is striking. The causes of motion sickness are both visual and mechanical, the latter arising from stimulation of the vestibular system. Animals in whom the vestibular system has been ablated or people born with non-functioning labryinths cannot be made motion sick. The cause of motion sickness has never been completely clarified but it is felt that it results from sensory conflicts, the difference between what is seen or felt and previous orientational experience. Motion sickness, for example, can occur in aircraft simulators and is more common amongst pilots experienced on the type of aircraft being simulated than it is in an inexperienced crew. It seems that the experienced pilot misses the cues of mechanical motion to which he/she is accustomed when the sensation of motion is only visually induced.

Frequency

Motion sickness increases in frequency up to puberty and then decreases. Women are more subject than men and it is more common in passengers than in aircrew. Motion sickness may be provoked by anxiety, fear or orientational insecurity. Unfortunately it can become a conditioned reflex. A trainee pilot, having been motion sick during flight, may become ill on the ground approaching an aircraft. It can be overcome by repeated exposure or adaptation and is rarely experienced by the person in charge of the aircraft (or automobile) who is aware, and braced for, changes in attitude or direction. Up to one third of military flight trainees become air sick at some point in their training and about 1 in 5 suffer severe air sickness. Despite this less than 1% of the trainees are failed because of this problem. Adaptation depends upon gradually increasing stimulation. In trainee pilots who develop severe problems, desensitization programs have been successfully employed.

Treatment

Motion sickness can be much reduced by the use of Scopolamine and nowadays transcutaneous administration of this medication is used in sea sickness. The drug however creates drowsiness and cholinergic effects and is not suitable for pilots. Small doses of the drug may be used in the initial phases of training when an instructor is in the aircraft but this must be discontinued before solo flight is undertaken. There is no place for prolonged drug therapy in aircrew.

Neurology

Foreword

A continuing challenge for those involved in the aeromedical certification process is in making decisions which take into consideration both the rights of the individual and the safety of the public. This is not always an easy task.

One of the areas that has been most challenging is neurology and neurosurgery. Making predictions about the likelihood of subtle or sudden incapacitation is at best an imprecise science. However, modern neurological diagnostic imaging techniques and prospective studies are making outcome predictions more reliable.

These guidelines have been prepared to assist practicing physicians determine whether or not their pilot patients may meet the neurological requirements for the aviation environment. The guidelines are the result of an analysis of the proceedings of a 2 day workshop on neurological disorders and aeromedical certification held in Ottawa, June 3rd and 4th 1992.

Physicians are reminded that this document should be used as a guide only and should not be confused with the medical standards for aviation personnel published by Transport Canada, Aviation (TP 195). Specific questions should be directed to the nearest regional aviation medical office, Civil Aviation Medicine Division, Health Canada. (appendix)

To all the panel members who participated in the workshop with such enthusiasm, and who gave so generously their expertise and precious time in the development of these guidelines I extend to each of you my sincere and respectful gratitude.

To Dr. Hyman Rabinovitch, neurology consultant to the Civil Aviation Medicine Review Board, and Dr. James M. Wallace, Senior Consultant, Operations Policy and Standards who shouldered the responsibility of writing and editing this document, I thank you for your dedication.

G.Y. Takahashi, M.D., D.Av.Med.
Director, Civil Aviation Medicine Division (CAM)
Health Canada

List of Participants

Dr. George Y. Takahashi
Director, Civil Aviation Medicine Division
CAM, Ottawa

Dr. James M. Wallace
Sr. Consultant, Operations, Policy and Standards,
CAM, Ottawa,
Co-Chairman

Dr. Hyman Rabinovitch
Consultant in Neurology,
Aviation Medical Review Board (AMRB),
Asst. Clinical Prof. University of Ottawa
Co-Chairman

Dr. Henery J. Barnett
Professor of Neurology,
University of Western Ontario, London, Ontario

Dr. Frederick Andermann
Professor of Neurology, McGill University,
Montreal, Quebec

Dr. Robert Nelson
Chairman, Division of Neurology,
University of Ottawa, Ottawa, Ontario

Dr. Donald Paty
Professor of Neurology,
University of British Columbia, Vancouver, B.C.

Dr. Donald Stuss
Director, Rotman Research Institute,
North York, Ontario

Dr. Robert Dupuis
Consultant in Internal Medicine, AMRB, Ottawa,
Assoc. Professor, University of Ottawa

Dr. Brian St. L. Liddy
Consultant in Ophthalmology, AMRB, Ottawa

Dr. David Schramm
Consultant in Otolaryngology, AMRB, Ottawa

Dr. Marvin Lange
Consultant in Psychiatry, AMRB, Ottawa

Dr. Paul King
Sr. Consultant Education & Training,
CAM, Ottawa

Dr. Guy Savoie
Chief Clinical Assessment,
CAM, Ottawa

Dr. Stephen V. Blizzard
Sr. Consultant, Safety and Human Factors,
CAM, Ottawa

Dr. Brent Haskell
Regional Aviation Medical Officer,
CAM, Ontario Region

Dr. James Nolan
Regional Aviation Medical Officer,
CAM, Central Region

Dr. Jennifer Gegg
Regional Aviation Medical Officer,
CAM, Western Region

Dr. Kenneth Boyd
Regional Aviation Medical Officer,
CAM, Pacific Region

Dr. François Dubé
Regional Aviation Medical Officer,
CAM, Quebec Region

Dr. Hart Corne
Acting Regional Aviation Medical Officer,
CAM, Atlantic Region

Mr. Larry Cundy
Superintendant, Personnel Licensing Standards
Transport Canada Aviation

Dr. Silvio Finkelstein
Chief, Aviation Medicine Section, International
Civil Aviation Organization, Montreal

Dr. William Hark
Office of Aviation Medicine, Federal Aviation
Administration, Washington, D.C., U.S.A.

Dr. William Doughty
Director, Medical Services,
Canadian Airlines International, Vancouver

Dr. Claude Thibeault
Director, Medical Services, Air Canada,
Montreal

Dr. Gary Gray
Defence and Civil Institute of Environmental
Medicine, Downsview, Ont.
Medical Advisor to Canadian Airline Pilots Assoc.

Captain David Noble
Canadian Airline Pilot's Association

Introduction

The Canadian Charter of Rights and Freedoms which was enacted in 1982 has a number of human rights provisions, one of which states that "no person shall be discriminated against on the basis of disability". Given this constitutional background there have been an increasing number of challenges in the Courts and Human Rights Tribunals on refusals to medically certify applicants with neurological disorders. Aeromedical "unfit" assessments must therefore be based on current scientific "state of the art" knowledge.

In the aviation environment neurological disease is a recurring concern for those involved in aeromedical certification. The mode of presentation may vary from full-blown grand mal seizures or massive stroke to the insidious onset of cognitive impairment in conditions such as multiple sclerosis and Alzheimer's disease. The prevalence and marked variability in severity of migraine has caused difficulty in objectively deciding where the line should be drawn between "fit" and "unfit" assessments. The person who has sustained a significant head injury is subject to the dual dilemma of risk of posttraumatic seizures and also of cognitive impairment.

In 1977 in the United States, the Federal Aviation Administration solicited a proposal from the American Medical Association (AMA) to produce an authoritative report on neurological disorders and aviation safety. The AMA in conjunction with the American Academy of Neurology and the American Association of Neurological Surgeons convened a series of meetings with experts in the field which resulted in the publication in 1979 of a special issue of the Archives of Neurology, entitled "Neurological and Neurosurgical Conditions Associated with Aviation Safety". This document served as one of the primary resources for Canadian aeromedical certification decisions on neurological disorders throughout the 1980's.

Advances in diagnostic imaging and the management of neurological and neurosurgical disorders over the intervening years indicated that more current references were required. In order to address these issues, Health & Welfare Canada's Civil Aviation Medicine Division held a conference in June 1992 in Ottawa, inviting experts in the field of neurology to discuss the more common neurological disorders and their relationship to aviation safety.

The conference served as a basis for the series of guidelines published below.

It should be pointed out that this document is only guidance material and that each decision will be based on the individual circumstances of the case.

Head Injury

General

There are two major concerns following head trauma resulting in loss of consciousness. One is the neuropsychological consequences of the trauma in patients who have not had any focal deficits. The other is the possibility of seizure secondary to the trauma.

The neuropsychological consequences are secondary to the effects of acceleration/deceleration forces on the skull and brain. Because of the anatomy involved, these forces cause their greatest focal damage to the orbital, frontal and anterior temporal areas of the brain. Associated with the cortical damage there is diffuse white matter damage.

The result of this is dysfunction in a number of functional executive activities of the brain. These frequently are, 1) slowing of reaction time, impaired memory and deficient ability to perform constantly at a high level over time, particularly in settings of complex activities and choices. 2) A high propensity for further mental decline with fatigue. Other problems include attention, initiation and proper sequencing of tasks, difficulty in planning and anticipating the future, and difficulty establishing automatic responses to a trigger. The affected individual may not notice or care that the task is being poorly performed. Problems are exacerbated by stress, fatigue and pain and the handling of simultaneous emergency tasks is particularly affected. Although the problems may be severe, routine IQ and mental status testing may be within normal limits. Fortunately there is a natural tendency for deficits to improve.

Prediction of Neuropsychological Outcome

Sufficient data to accurately predict the outcome of most types of head injury is unfortunately unavailable. There are a number of ways to predict the outcome of head injury and the most commonly used to date has been the duration of post-traumatic amnesia (PTA). Most individuals who have had a PTAof less than 30 minutes are likely to be fit within three months. Older individuals and/or those who have a history of previous concussion are of greater concern. A person with PTA lasting more than 30 minutes but less than 24 hours will likely be fit from a neuropsychological point of view after a longer time, probably one year.

Those with focal neurological deficits, those who have focal abnormalities on CT scanning or a more prolonged PTA require neuropsychological assessment with particular attention to frontal lobe functioning before medical certification. Flight simulator testing may be useful. Magnetic resonance imaging (MRI) is more sensitive than CT scanning in defining areas of frontal lobe and white matter abnormality and is therefore an important diagnostic adjunct in those who have had brain injuries. These people clearly require a more prolonged period off work than those with simple concussion.

Prediction of Posttraumatic Epilepsy

The probability of epilepsy is greater in those with penetrating skull injuries. Even with full physical and neuropsychological recovery there is an increased probability of seizures for over ten years. In general, of those who develop post traumatic seizures, 50% will occur within one year and 70 - 80% within two years. Thereafter the incidence is 3 - 5% per year up to ten years. The probability of seizures has been correlated with CT scan findings as illustrated in Table 1.

Table 1 - Risk Factors for Late Posttraumatic Epilepsy

	Incidence of Late Seizures (%)
Penetrating injury caused by missile	53
Intracerebral haematoma - laceration	39
Focal brain damage on early CT scan	32
Early seizures	25
Depressed fracture - torn dura	25
Extradural or subdural haemorrhage	20
Focal signs (hemiplegia, aphasia,..)	20
Depressed skull fracture	15
Loss of consciousness > 24 hours	5
Linear fracture	5
Mild concussion	1
Pagni C.A. (1990) Post-traumatic Epilepsy and Prophylaxis: Acta Neurochirurgica, Suppl. 50, 38-47 (1990)

Aeromedical Status

Those with PTA lasting 30 minutes or less, who after the event, have a normal neurological examination without sequelae, may be medically certified in three to four months if the CT scan is normal.
Those with PTA lasting from 30 minutes to 24 hours but with a normal MRI and EEG, may be medically certified by one year. If a seizure occurred in the first week after trauma in an adult, a longer interval before medical certification is indicated.
Those with PTA greater than 24 hours but who have normal neuroimaging and neuropsychological testing, may be medically certified by two years. Flight simulator testing may provide additional valuable information in these cases.
Those with closed head injury with extracerebral haemorrhage, but without dural tear or intracerebral involvement may return to full duties by five years. An EEG and neuroimaging should be undertaken at that time.
Those with closed head injuries with associated intracerebral haemorrhage or focal deficit, but whose neuropsychological testing does not show significant residua 7 years post trauma, may be considered at that time. Those who demonstrate abnormal neuropsychological residua have been more seriously injured and should be considered individually.
Those with penetrating skull injuries from a missile are unfit for 15 years even if neuropsychologically normal because of the continuing excess risk of posttraumatic epilepsy.

Chronic Subdural Hematoma

These can occur at any age, though they are more common in the older age group. Individuals frequently are unaware of significant head trauma.

Postevacuation if the applicant has:

no sequelae and
no seizures in the year following surgery and
no significant abnormality on CT scanning and sleep deprived EEG, they may be considered for medical certification.

Stroke and Transient Ischemic Attack (TIA)

General

Stroke is the third most common cause of death and a leading cause of disability in Canada. The risk of a recurrent stroke following an initial TIA or stroke has been looked at in a number of trials of various antiplatelet medications. These studies show about an 8% per annum risk of recurrence and about 2-3% risk of a myocardial infarction. The probability of recurrence does depend on the number of risk factors present and the degree of carotid artery stenosis.

Blood pressure control, cholesterol control, antiplatelet medications and cessation of smoking have made significance inroads into reducing the risk of stroke. Surgery has been particularly successful in patients who have significant carotid stenosis. Nevertheless, despite these management techniques, the risk of recurrent stroke remains high. Therefore, the vast majority of applicants who have had a stroke, will remain permanently unfit. All applicants with stroke secondary to an intracerebal hemorrhage are permanently unfit.

Modifying Considerations

Transient Ischaemic Attacks

The applicant who has a TIA must be evaluated carefully as some will in reality be migraine without headache, seizures, vestibular dysfunction, failure of ocular fusion, multiple sclerosis, brain tumors, subdural hematoma, hypoglycemia or syncope. Risk factors have to be carefully evaluated including possible cardiac sources of embolus. Applicants with negative imaging of brain, neck and heart and with minimal other risk factors can be considered for medical certification at three years after the event.

Lacunes

These are a specific symptom complex with an appropriate abnormality on neuroimaging ascribed to a lacune. The majority are secondary to small vessel occlusion, others may be secondary to an embolus of various possible origins. They pose two problems one is the risk of recurrent infarct which is significant and the second is the accumulation of lacunes without obvious symptomatology but leading to the insidious onset of dementia The majority of applicants with lacunar infarcts are therefore unfit. Occasional individuals who never had significant deficits and who fully recovered may be considered on an individual basis. These individuals require extensive work-up, including carotid Doppler studies and echocardiography. They need an MRI to show if there is evidence of significant lacunar disease. If the above investigations do not show significant pathology, the risk factors are controlled and if after four years, the MRI does not show any increase of lacunar disease, the applicant could be considered on an individual basis for medical certification. Applicants with multiple lacunes are a concern, as they may be developing dementia and are unfit.

A patent foramen ovale should not be considered a risk factor for stroke according to recent trials, unless associated with an atrial septal aneurysm.

Cerebral Venous Thrombosis

Approximately 70% of people who have venous thrombosis, have a clear predisposing factor, such as factor 5 Leiden deficiency, Protein C or S deficiency, anti-thrombin 3 deficiency, or, PGM deficiency, trauma, infection or dehydration, anovulents, pregnancy and Methylenedioxymetamphetamine (Ecstasy). If there is no evidence of an ongoing or recurrent risk, if there has been no evidence of epilepsy and if the person has no significant sequelae from the thrombosis, they can be considered medically fit two years after the event.

Pregnancy in Stroke

During pregnancy and puerperium the risk of stroke is 44 per 100,000. The cause for this type of stroke must to be sought as often multiple factors predispose towards such strokes. One has to look particularly for thrombophilia, anti-phospholipid antibodies, dehydration, cardiac disease and dissection. In those individuals where there has been no significant sequelae, particularly no cognitive difficulties or history of epilepsy and if the etiology of their stroke is not going to be a recurrent or ongoing problem, then they could be considered fit two years after the event.

Asymptomatic Stenosis

Applicants who are found to have an 80% or greater stenosis of the carotid artery are at increased risk of stroke, TIA or myocardial infarct. They are unfit. An endarterectomy will not resolve this problem, as they probably have other arteries significantly involved.

Arterial Dissections

Arterial dissections are one of the most common causes of stroke in the young. Applicants who have had a good recovery, in which imaging does not show any evidence of cerebral infarction, who have had no evidence of epileptic seizures, can be considered for medical certification after two years. They need imaging to show good restitution of flow, with no evidence of aneurysm. There should be no evidence of having had a subarachnoid hemorrhage. There should be no predisposition to further dissections.

Ruptured Aneurysms

The majority of applicants who have had a subarachnoid hemorrhage are permanently unfit. There are occasional people who have been successfully treated, who had excellent recovery, and who have never had seizures. Those individuals in which repeated angiography shows that the treatment has been successful can be considered for medical certification at two years. If they had an endovascular approach, an angiogram should be repeated yearly for two further years, to show that successful repair has been maintained. An EEG at two years should not show significant abnormalities and particularly no potentially epileptiform discharges. Those who have perimesencephalic bleeds with normal angiography, could be considered fit at one year if they have had an excellent recovery, as is usually the case. Those with asymptomatic intracranial aneurysms less than 10 mm can be considered as continuing to be medically fit.

Arterio Venous Malformations

Those who are asymptomatic usually have a risk of 2-4 % per year of hemorrhage. Those who have been previously symptomatic have a risk as high as 33% in the first year. Therefore those with arteriovenous malformations are permanently unfit.

Cavernomas

Applicants with cavernomas that are deep, with no evidence of previous hemorrhage may be considered fit, all others should be considered unfit.

Seizure Disorders

General

The tendency towards epileptic seizures is not an all or nothing phenomenon. Most people, under certain conditions, may have a seizure if sleep deprived or withdrawing from alcohol or benzodiazapines, especially if in addition they are taking medications which decrease the seizure threshold (eg. Tricyclic anti-depressants). Approximately 2% of the population will have a seizure during their lifetime.

An adult with a single seizure has a 30 - 40% chance of recurrence. Those with a distinct epileptiform abnormality on the EEG as opposed to non specific abnormalities, have an increased probability of having further seizures after a single seizure. It is therefore imperative that the diagnosis of a seizure be correct, and the importance of a description of the event cannot be overemphasized. Although the electroencephalogram (EEG) is particularly useful it must be reviewed by an experienced reader to be considered supportive of an epileptiform tendency. Individuals with epilepsy are unfit.

Persons who have had the following types of seizures may be acceptable. Childhood febrile seizures which are brief, not associated with neurological deficits, and have ceased before the age of five may be considered for medical certification. The individual must have been off all anti-epileptic medications for at least five years and the EEG (off medication) must be normal. The seizures of Benign Rolandic Epilepsy of Childhood usually involve the face, tongue or hand and are often precipitated by drowsiness or sleep. The EEG shows significant abnormalities from the Rolandic area of the brain. Individuals with this condition may be considered for medical certification if they have been seizure free and off medication for ten years. They must have a normal neurological examination and EEG. A sleep deprived EEG should also be normal.

The Single Epileptic Seizure

An individual with a single epileptic seizure is initially unfit. The case can be reconsidered after five years if the neurological examination is normal and repeated EEGs, including sleep deprivation and additional nasopharyngeal or minisphenoidal electrodes, do not reveal any significant abnormalities. Neuroimaging, preferably MRI, must first have revealed a normal brain structure. A restricted (as or with co-pilot) medical certificate can then be granted. Such a restriction may be removed after an additional two years. Those individuals who have a second seizure should be considered to have epilepsy.

Five years after the event, all of the above investigations must be repeated and found to be normal. Applicants for Category 1 medical certification should be restricted to: "as or with copilot" for an additional two years. Those individuals who have a second seizure should be considered to have epilepsy.

When a single seizure was related to alcohol withdrawal, individuals may be considered earlier if they have a normal EEG and neuroimaging and psychosocial and biochemical evidence is presented that their alcohol abuse/dependence is in a continuing "recovery" phase.

Those who have had a seizure while on tricyclic antidepressant drugs or other seizure enhancing medications must be considered more prone to seizures than the average population. They must be considered unfit for five years.

Transient Global Amnesia (TGA)

This condition is characterized by a transient loss of memory for remote events associated with an inability to form new memories. It is an unusual condition that usually lasts for hours. TGA is not a seizure disorder and may be due to transient ischemia in the inferomedial parts of the temporal lobes. It is commoner in middle aged or older people, and many individuals are hypertensive: frequently they have been undertaking physically demanding tasks (eg. shoveling snow) or under significant mental stress at the time of the attack.

Throughout the episode, the sufferer is socially appropriate, oriented to person but tends to repeat the same question over and over again, this question usually reflecting their disorientation. (eg. "What am I doing here?") A number of series have shown a 10 - 20% recurrence, most of which occur within the first five years.

If there is a normal neurological examination and EEG at the time of the event and again one year after the event, medical certification may be considered.

Narcolepsy

Narcolepsy presents with periods of excessive daytime sleepiness not prevented by adequate nighttime sleep and often enhanced by boredom. Excessive sleepiness may be associated with sleep related hallucinations or paralysis and, most importantly, it may be associated with cataplexy which is an abrupt paralysis of variable degree precipitated by surprise or by laughter. Prophylactic medications are imperfect and may alter performance. They include dextroamphetamine and methylphenidate.

Narcolepsy is a lifetime illness and the sufferer is permanently unfit.

Headaches

Tension and Migraine Headaches

General

Fifty-nine percent of the adult population in Canada report some form of headache. Thirty percent suffer from tension-type headaches, and 17% suffer from some form of migraine. Tension type headaches are not usually disabling but up to three quarters of migraine headaches are sufficiently severe to limit regular activities. Most migraineurs have attacks that last 12 to 24 hours.

Migraine can be divided into two categories, migraine with aura (classical migraine) and migraine without aura (common migraine). The aura may be preceded by a prodrome of mood changes which may interfere with routine activities. The aura itself usually lasts about 20 minutes and immediately precedes the onset of the headache. The cause of the aura has been debated but may be secondary to metabolic and/or electrical changes which may possibly be accompanied by ischemic change in the cerebral cortex. The head pain itself is thought to be related to a sterile inflammatory response around blood vessels in the face and scalp and the intracranial vessels of the coverings of the brain. This inflammatory response is mediated through vasoactive peptides which cause dilatation, edema and inflammation around the vessels which are innervated by a branch of the trigeminal nerve (trigeminal-vascular complex).

Migraine tends to occur at times of let-down from stress, after fasting, and after missing sleep. Flashing lights and bright reflected light may also trigger acute attacks.

Aeromedical Status

Migraine without aura - Most applicants will be considered fit.

Migraine with Aura

Group 1.

Applicants with auras which:

would not interfere with flight safety and,
have been consistently the same aura over several years, can generally be considered for medical certification.

Group 2.

Applicants with auras that:

are of slow onset; and
occur infrequently ie. once every several months; and,
are not associated with cognitive impairment, but may cause minor sensory difficulty that does not impair performance; and
have been consistently the same over several years.

Group 3.

Migraineurs who have significant auras which can interfere with flight safety and who do not fit into the group 2, (ie, too fast onset, too frequent, cognitive impairment, unclear history,) should generally be considered unfit for all categories. They may be considered for restricted medical certification if after 3 years they fit in group 2.

Cluster Headaches

Cluster headaches occur only in 0.1% of the population and are generally episodic and 80% of the cases occur in men. The headaches usually last about one hour and 50% of the cases begin during sleep. They recur in bouts lasting six weeks or more, during which time acute attacks occur one to four times per 24 hours. Once the bout is ended, however, the sufferers are usually entirely headache free for months or years. The individual attacks are extremely intense, localized around one eye and associated with nasal congestion and lacrimation which may impair vision. They are virtually always incapacitating. The applicants should be considered unfit during a bout of cluster headache but during the interval bouts, they may be considered fit. Between bouts, the applicants do not need to take any medication, but in chronic cluster headache where the bout extends beyond six weeks, medication which might impair functioning may be required.

Trigeminal Neuralgia

Trigeminal Neuralgia causes piercing, electric shocklike facial pains which have a high frequency of recurrence. Many episodes may occur in a single day. In older age groups these are often secondary to a loop of blood vessels pressing against the trigeminal nerve: in the young they may be secondary to multiple sclerosis. Individuals suffering from trigeminal neuralgia are unfit but if they go into remission may be considered for medical certification.

Multiple Sclerosis

General

Multiple Sclerosis (MS) has a prevalence of about one in a thousand in Canada. The peak incidence is in the early 30's with more females than males being affected. It is the third most common cause of severe neurological impairment in the 15-60 year age range. The course is variable. Some will have a relapsing, remitting course and 20 - 30% will have a benign course. Fatigue is one of the most disabling problems in patients with multiple sclerosis. In 60% of the patients the symptoms are exacerbated by an elevated ambient temperature.

Flight Safety Concerns

Functional Disabilities

Though many of these will be readily apparent from a practical flight test, (eg. weakness, lack of coordination etc.) they also include problems with excessive glare in bright light and increased levels of fatigue.
Neuropsychological Deficits

40% of the patients with MS have been found to have neuropsychological problems. This is significantly but weakly correlated with the degree of functional disability.
Paroxysmal Events

Epilepsy occurs in 5% of patients with MS. Trigeminal Neuralgia is commonly a symptom of MS when it occurs in the young. Paroxysmal dysfunction of motor or sensory systems may occur with this disease.

Recommendations

Functional Disabilities

Individuals with functional disabilities that interfere with the mechanics of flying or those who have a progressive course of MS will be considered unfit. This is also true of those who suffer significant fatigue or heat sensitivity. Individuals who have a remitting/relapsing course may be considered fit when they have been in remission for three months provided the remission is complete or with minimal residua (eg. Expanded Disability Score of less than 2 on a scale of 0 - 10). Such individuals will require neurological follow-up every six months.
Neuropsychological Sequelae

Because of the concern for subtle neuropsychological deficits, applicants should probably be followed by a neurologist with expertise in M.S. Neuropsychological testing should be considered periodically especially in those who have significant fluctuation in symptoms. Flight simulator testing may be useful in assessing cognitive function. The role of MRI to delineate those who may have neuropsychological deficits has not been defined at this time. Those with marked involvement of the white matter with MS plaques, particularly if the involvement is bifrontal, should have neuropsychological testing and, if indicated, a practical flight test.
Paroxysmal Events
1. Epileptic Seizures
  
  These individuals are permanently unfit.
2. Trigeminal Neuralgia
  
  Applicants are unfit during periods when they are symptomatic. It is unusual for these to resolve and most continue to be unfit.
3. Other Paroxysms
  
  Usually these are of limited duration. If they resolve and are absent for four months off medication the individual can be reconsidered for medical certification.

Tumors

General

Tumors arising from the brain parenchyma such as gliomas or ependymomas, even when removed and whether or not they are treated with a radiotherapy, leave behind scarring. This increases the probability of seizures and applicants with such a history are therefore permanently unfit.

Meningiomas

Applicants who have had meningiomas of the cerebral convexities may be considered fit two years post resection under certain specific circumstances. Current literature suggests that there is no limit as to when a meningioma can recur. The tumor must have been fully removed as defined by repeated neuroimaging. There should be no neurological sequelae and no history of seizures in association with the tumor. If a medical certification is granted a repeat EEG and CT scan must be done at yearly intervals.

Infratentorial Meningiomas, Acoustic Neuromas, Pituitary Tumors and other Benign Extra-axial Tumors

Applicants who have had complete resection of an infratentorial meningioma, acoustic neuroma or other benign extra axial tumors, or applicants who have had a transphenoidal complete resection of a pituitary tumor and have no neurological or endocrinological sequelae and no history of seizures may be relicenced after 6 months to one year. They will require yearly neurological and endocrinological follow-up.

Those who have had an elevation of the frontal lobes in order to approach the pituitary tumor are generally unfit. This is because the tumor is probably larger and more likely to disturb structures around it and the frontal lobe has been disturbed by the traction involved in the surgery. These factors increase the chance of the applicant developing seizures.

Miscellaneous Illnesses

Hydrocephalus

Individuals who have required a shunt to control hydrocephalus may have shunt failure and/or require a new shunt. Those shunted for acquired hydrocephalus are generally unfit because of the possibility of unexpected shunt failure. Individual consideration however may be given where accredited medical opinion is that the risk of shunt failure or seizure is low.

Applicants shunted in infancy and seizure free throughout adult life without neuropsychological sequelae may be considered for a Category 3 medical certificate.

Syringomyelia

This is a rare condition in which there is a cystic lesion of the spinal cord or brainstem. These lesions usually develop because of congenital anomalies, less frequently secondary to trauma or tumor. They tend to progress.

If the syrinx is below the cervical cord the applicant should be judged as any other paraparetic according to functional abilities. A practical flight test will be required and, after medical certification, neurological follow-up is required every six months. A practical flight test should be repeated annually.

In applicants where the syrinx involves the cervical cord or brainstem, the neurological deficit may be or become too significant for medical certification. Such applicants are permanently unfit.

Myasthenia Gravis (MG)

Neuromuscular dysfunction in MG is related to antibodies generated against the acetylcholine receptor at the neuromuscular junction. This results in progressive weakness and fatigability which fluctuates with the degree of effort sustained. Some individuals may achieve a remission by thymectomy or immunosuppression. Those who are in remission and stable, with little or no medication two years after the thymectomy, may be recertified.

Infections

Viral Meningitis - An applicant who is neurologically normal at two months after infection will be considered fit, all categories.
Bacterial Meningitis - If the individual is found to be neurologically normal on examination, electroencephalography and CT scanning and if they have had no focal or neurological deficits or seizures during the bacterial meningitis, they may be considered fit after one year.

If there were complications such as focal neurological deficits, persistent cognitive deficits or seizures, the applicant must be fully neurologically intact for five years while off all medications before being recertified. Arepeat CT scan, EEG and a neurological assessment should be performed at five years prior to recertification. If there were cognitive deficits post resolution, neuropsychological testing should be carried out.
Viral Encephalitis - The most common, sporadic, viral encephalitis in North America is Herpes Simplex encephalitis. Neuropsychological sequelae are virtually always present, even in those who have survived seemingly neurologically intact.

Generally applicants who have suffered this disease will be permanently unfit. In cases however where there is complete neurological recovery and neuropsychological testing shows no significant deficit, individuals who have not had a seizure for five years off all medication can be considered for medical certification. If the disease manifested minimal or no cognitive dysfunction then a shorter unfit period prior to medical certification may be considered.
Brain Abscesses - Applicants who have had a brain abscess are at an increased risk for epilepsy from the scarring that forms around the abscess. They are therefore permanently unfit.
Guillain-Barré Syndrome - Applicants who have made a satisfactory neurological recovery may be certified following a successful practical flight test.

Degenerative Disease of the Brain

Parkinson's Disease - Most applicants with Parkinsonism suffer physical and/or cognitive deficits which render them unfit. Individuals who have minimal Parkinson's disease, such that they do not require L-dopa or an L-dopa agonist, may be certified. All patients licensed with Parkinson's disease must have a satisfactory neurological assessment at each renewal and more frequently if clinically indicated.
Dementia - Applicants with dementia are permanently unfit. In the small number of cases where the cause of the dementia is known and the condition has been resolved, applicants may be considered for recertification.

Cardiovascular

Guidelines for the Assessment of Cardiovascular Fitness in Licensed Aviation Personnel 2012

Foreword to the 4th Edition

The presence or development of cardiovascular disease in licensed aviation personnel, with the risk of potential clinical manifestations, continues to be a major concern to aviation medical practitioners. The evaluation and management of aeromedical risk continues to be a balancing act between practicality, risk tolerance and the advances of diagnostic medicine.

The advances in medical and surgical treatment of cardiovascular disease have allowed many pilots and air traffic controllers to return, after successful treatment, to licensed duties without jeopardizing aviation safety.

This fourth edition of the Canadian cardiovascular guidelines is intended to assist in the medical assessment of cardiovascular fitness of licensed aviation personnel. It reflects a consensus reached as a result of discussions and recommendations made during an aviation cardiology workshop held in Ottawa, on February 1st, 2010, arranged by Civil Aviation Medicine Branch, Transport Canada.

It must be emphasized that these guidelines are to be used only as a guide to practice and evaluation of licensed aviation personnel. No publication can hope to keep up with all the advances in this rapidly evolving field and each licence holder’s individual situation must be investigated and evaluated in light of the most up-to-date clinical guidance. These guidelines should not be confused with the medical regulations set out in the Canadian Aviation Regulations part 424 published by Transport Canada.

Civil Aviation Medicine Branch, Transport Canada, is very grateful for the enthusiastic support and participation of all the expert panel members, and other individuals who provided advice and criticism. A special word of thanks is owed to Dr. Andreas T. Wielgosz for his efforts in planning and co-chairing the workshop, and taking on the task of writing the text and to Dr. François Dubé who worked on the French translation.

Comments are always welcome, and any specific questions should be directed to Civil Aviation Medicine Branch, Transport Canada Ottawa or to any Regional Aviation Medical Officer. Contact information is available at

https://tc.canada.ca/en/aviation/civil-aviation-contacts-offices#civil_aviation_medicine

David A. Salisbury MD MHSc FACPM FRCPC
Director, Civil Aviation Medicine, Transport Canada

List of Participants Cardiology 2010

Chairpersons:

Dr. David Salisbury
Director, Civil Aviation Medicine, Transport Canada,
Ottawa ON

and

Dr. Andreas T. Wielgosz
Consultant Cardiologist,
Aviation Medical Review Board,
Division of Cardiology,
The Ottawa Hospital - General Campus and
Professor, Departments of Medicine and
Epidemiology and Community Medicine,
University of Ottawa ON.

Principal Author:

Dr. Andreas T. Wielgosz.

Invited Subject Matter Experts:

Dr. Michael Freeman
Medical Director Heart and Vascular Program,
St. Michael's Hospital, Toronto, ON

Dr. Eric A. Cohen
Director, Cardiac Catheterization Laboratory
Staff Cardiologist, Sunnybrook & Women's
College Health Sciences Centre, Toronto, ON
Associate Professor of Medicine,
University of Toronto

Dr. Ian G. Burwash
University of Ottawa Heart Institute,
Associate Professor of Medicine
University of Ottawa, Ottawa ON

Dr. Christopher S. Simpson
Kingston General Hospital
Kingston ON

Dr. Gary Gray
Internal Medicine and Cardiology
Defence Research and Development-Canada, Toronto, ON

Dr. François Dubé
Aviation Medical Officer,
Ottawa, ON

Dr. James Pfaff
Senior Consultant, Policy and Programs
Civil Aviation Medicine, Toronto ON

Dr. Edward Brook
Senior Consultant Education and Safety
Civil Aviation Medicine, Ottawa, ON

Dr. Jay Danforth
Senior Regional Aviation Medical Officer,
Prairie & Northern Region, Edmonton, AB

Dr. Ronald Davidson
Acting Regional Aviation Medical Officer
Atlantic and Overseas Region, Ottawa, ON

Dr. Guy Savoie
Regional Aviation Medical Officer
Quebec Region, Dorval QC

Dr. Dietmar Raudzus
Regional Aviation Medical Officer
Pacific Region, Vancouver, BC

Dr. Edward Bekeris
Acting Regional Aviation Medical Officer
Ontario Region, Toronto ON

Dr. Heather Langille
Aviation Medical Officer,
Civil Aviation Medicine, Ottawa, ON

Invited Observers

Col. Scott Mcleod
Medical Advisor to the Chief of the Air Staff,
Ottawa ON

Mr. Arlo Speer
Chief, Flight Crew Licensing & Aircraft Registration, Transport Canada,
Ottawa ON

Dr. Jon Stuart
Principal Human Performance Analyst
Transportation Safety Board,
Ottawa ON

Introduction

No disease condition is as rich with data to determine risk of medical fitness to fly as cardiovascular disease. Eight years have elapsed since the last review of the Guidelines for the Assessment of Cardiovascular Fitness in Canadian Licensed Aviation Personnel. Significant progress is being made in the identification of subsets of patients who are at high risk of a cardiovascular event based on more sophisticated technologies and expanding databases of well defined cases. Genetic epidemiology, still in its early stages contributes even more precision to an assessment of risk in individuals. The challenge remains to identify in a cost effective manner those at an unacceptably high risk of incapacitation among the majority of otherwise medically fit pilots and air traffic controllers. This challenge is compounded by the continuous aging of the pilot population as well as the entry of older Canadians who wish to take up flying for the first time. The likelihood of a cardiovascular event increases with age, therefore it is reasonable to consider the application of a different level of scrutiny to older individuals. Nevertheless there are pilots in their 70s and 80s who have been assessed medically fit to fly.

Cardiovascular experts who recently (February 1, 2010) reviewed the Guidelines published in 2002 felt that only a few updates and refinements were required and these have been incorporated. The one day Workshop included Regional Aviation Medical Officers, cardiovascular and aviation medicine consultants including from the Armed Forces and staff from the Civil Aviation Medicine Branch and Air Safety, Transport Canada.

The Guidelines in effect seem to be serving us well as evidenced by no fatal aviation accident in Canada over several decades, with an established cardiovascular cause.

Aviation Medical Standards are laid down in Annex 1 to the Convention on International Civil Aviation by the International Civil Aviation Organization (ICAO) to which Canada is a contracting state. The standards identify broad medical conditions that on the basis of expected risk of incapacitation disqualify a pilot from flying an aircraft. In countries where the standards are applied strictly, affected pilots may never return to flying. Such a strict policy may be unfair to those aviation personnel in whom the risk of sudden incapacitation becomes acceptably low as a result of risk factor modification or rehabilitation including some therapeutic interventions. Canada on the other hand has used the concept of flexibility and accredited medical opinion to determine medical fitness where circumstances do not meet the standards as written.

Our ability to assess risk in an individual continues to improve as experience with groups bearing similar risk profiles increases. Progress with the assurance of a safe flying environment e.g. through widespread incapacitation training, has also allowed more tolerance of certain medical conditions. The risk of a fatal accident occurring as a result of medical incapacitation is dependent on a number of factors. These include the amount of time spent flying, the type of flying (eg aerobatics), the risk of an incapacitation occurring at a critical phase of flight and the risk that such incapacitation is not mitigated by the presence of other qualified aircrew. All of these factors must be taken into consideration in addition to the known medical risk of a given medical condition.

Experience with cardiac disease in the general population along with experience with simulators allows an estimation of risk in a fashion similar to that used in other risk evaluation settings by structural engineers. It can be rationalized that an annual risk of incapacitation up to 2% (which includes a 1% risk due to a fatal occurrence as well as a 1% risk due to an incapacitating but nonfatal occurrence) due to a medical condition in an unrestricted pilot can be tolerated, as that would translate into an acceptably low risk of a resulting fatal accident. Where there is insufficient precision in estimating risk for the medical condition of a given applicant, then we continue to determine medical fitness applying a cautious approach.

Chapter 1: Ischemic Heart Disease

Chest Pain

Chest pain, regardless whether typical or atypical for ischemic heart disease, precludes medical certification insofar as it indicates an elevated probability of significant coronary artery disease and an increased risk of an incapacitating cardiac event.

An applicant may be considered medically fit if diagnostic testing indicates that the chest pain is not due to myocardial ischemia. The initial assessment including a review of the symptom history must be made without the effect of anti-ischemic medications that could possibly mask adverse findings. If coronary arteriography reveals normal coronary arteries, coronary vasospasm should be clinically excluded. The presence of continuing symptoms of chest pain in the absence of ischemia is not disqualifying per se; however, such symptoms must not be incapacitating in any way.

Acute Coronary Syndrome

Acute coronary syndromes include unstable angina, non-ST elevation (NSTEMI) as well as ST elevation (STEMI) myocardial infarctions. An acute coronary syndrome is initially incompatible with medical certification. However, disqualification is not necessarily permanent, and medical certification may be considered 6 months after the event (a decision at 6 months must be based on requisite assessments completed no sooner than 5 months after discharge from hospital) provided the following criteria are met:

The result of an exercise test to a minimum of 8.5 METS using the Bruce protocol or equivalent places the individual at low (<2%) risk of a significant cardiovascular event over the following 12 months. If a perfusion exercise test is used, there should be no significant reversible defect and no large fixed deficit as explained in the next point.
The left ventricular ejection fraction as a measure of left ventricular function using echocardiography or gated radionuclide scintigraphy, is better than 50% at rest and does not show a decrease of more than 5% with satisfactory exertion (i.e. 85% predicted maximum heart rate or > 8 METS). A threshold ejection fraction of 45% applies with the use of SPECT (single proton emission computerized tomography) scanning.
With a satisfactory ejection fraction as described above, Holter monitoring is not required. For an ejection fraction between 40% and 50%, restricted medical certification may be considered after review of a 24 hour Holter monitor. This should reveal no more than 3 ventricular ectopic beats per hour in the absence of antiarrhythmic medication, with no more than 3 consecutive beats and a cycle length that is not less that 500 msec.
Major modifiable risk factors (see below) for recurrence of infarction are controlled, and the applicant is a non-smoker.

Medications need not be stopped for these tests.

Extensive and severe coronary disease, particularly if the left main coronary artery is involved with disease, even if revascularized will likely be viewed unfavourably.

A follow-up assessment a year after the infarction and then annually should include a thorough history, physical examination, rest and exercise electrocardiography and a review of modifiable risk factors. If there is no clinical deterioration after 2 years, the treadmill exercise test can be done every 2 years until a need for yearly testing is indicated.

These criteria apply regardless of whether the applicant was treated for acute thrombosis with a thrombolytic drug, percutaneous coronary intervention (PCI) or bypass surgery, or the infarction occurred in the presence of only mild to moderate atheromatous disease as demonstrated by arteriography.

Following Revascularization

An applicant who has been treated for coronary artery disease by revascularization including bypass surgery, angioplasty with or without stenting, directional atherectomy etc., can be considered for medical certification after an interval of 6 months, with testing completed not earlier than 5 months after the revascularization. The criteria for consideration are the same as following an ACS (above).

The older individual and/or those with increased complexity of coronary disease, e.g., multi-vessel involvement will likely need on-going yearly assessments.

Risk Factors for Ischemic Heart Disease

The following are major modifiable risk factors for ischemic heart disease. While many of them may have impressively large relative risks, their absolute risk, particularly for sudden incapacitation, is low. Concern about these risk factors is greater in applicants with known ischemic heart disease where the absolute risk is greater. The presence of major modifiable risk factors should be a concern in any applicant and preventive measures are strongly advised.

Smoking

Prohibition of smoking in the cockpit is now the norm for all flights of any duration. Anyone with known ischemic heart disease who continues to smoke is considered medically unfit.

Increased serum cholesterol levels

All applicants are encouraged to be aware of their serum lipid levels and to maintain normal levels. Target levels depend on the level of risk as outlined in the 2009 Canadian Cardiovascular Society Guidelines. Table 1. All currently approved medications for lipid lowering are compatible with flying.

Table 1 - Target Lipid Levels

Risk level	Primary Target: LDL-C	Alternate Target
High CAD, PVD, Atheroscelrosis Most patients with diabetes FRS ³20% RRS ³20%	<2 mmol/L or ³50% ¯LDL-C	apoB <0.80 g/L
Moderate FRS 10% - 19% LDL-C >3.5 mmol/L TC/HDL-C >5.0 Hs-CRP >2 mg/L Men >50 years Women > 60 years Family history and Hs-CRP modulates Risk (RRS)	<2 mmol/L or ³50% ¯ LDL-C	apoB <0.80 g/L
Low FRS <10%	³50% ¯ LDL-C

Risk level

Primary Target: LDL-C

Alternate Target

High

CAD, PVD,

Atheroscelrosis

Most patients with diabetes

FRS ³20%

RRS ³20%

<2 mmol/L

³50% ¯LDL-C

apoB <0.80 g/L

Moderate

FRS 10% - 19%

LDL-C >3.5 mmol/L

TC/HDL-C >5.0

Hs-CRP >2 mg/L

Men >50 years

Women > 60 years

Family history and

Hs-CRP modulates

Risk (RRS)

<2 mmol/L

³50% ¯ LDL-C

apoB <0.80 g/L

Low

FRS <10%

³50% ¯ LDL-C

High Blood Pressure

The recommended approach to the diagnosis of hypertension is in keeping with that of the Canadian Hypertension Education Program (CHEP). In licence holders with accurately measured blood pressure, if the systolic blood pressure (SBP) is 140 mmHg or greater and/or the diastolic blood pressure (DBP) is 90 mmHg or greater, a specific visit should be scheduled for the assessment of hypertension. The process to follow in order to establish the diagnosis of hypertension as well as pharmacologic and nonpharmacologic treatment strategies are outlined in the CHEP recommendations (https://hypertension.ca/bpdevices), the details of which are beyond the scope of these Guidelines.

For the assessment of medical fitness in pilot applicants, it is important that hypertension be controlled. If pressures remain at or above 160 mmHg systolic or 100 mmHg diastolic, it is strongly recommended that drug treatment be initiated. Treatment should also be considered when the diastolic pressure is between 90 and 100 mmHg in the presence of macrovascular target organ damage or other independent cardiovascular risk factors. The goal of systolic blood pressure treatment is <140 mmHg and <90 mmHg for diastolic blood pressure. For anyone with diabetes as well as non-diabetic chronic kidney disease, the target blood pressure is <130/80 mmHg.

Medical certification can be granted when treatment has been successful in reducing the blood pressure below 160 mmHg systolic and below 100 mmHg diastolic, however optimal blood pressure is less than 120/80 mmHg in most individuals including the elderly and to less than 130/80 mmHg in those with diabetes or renal dysfunction. On any visit, a blood pressure level of 180 mmHg or more systolic or 110 mmHg or more diastolic is incompatible with medical certification.

Therapeutic Considerations

Initial therapy should be monotherapy with a thiazide diuretic; a beta-blocker (in those younger than 60 years of age); an ACE inhibitor (in nonblack patients); a long-acting CCB or an ARB. If there are adverse effects, another drug from this group should be substituted. Hypokalemia should be avoided in patients treated with thiazide diuretic monotherapy.

Additional antihypertensive drugs should be used if target blood pressure levels are not achieved with standard dose monotherapy. Add-on drugs should be chosen from first line choices. Beta-blockers are included for those under 60 years of age. In licence holders, the major challenges with treatment are to minimize postural hypotension, the risks of arrhythmias and adverse CNS effects.

Preferred drugs in an aviation environment include:

ß-blockers: hydrophilic drugs are preferred (e.g. atenolol, nadolol, timolol).
Calcium channel antagonists: long-acting dihydropyridines are preferred (e.g. amlodipine, felodipine, nifedipine XL).
ACE-inhibitors: long-acting ACE-inhibitors are preferred such as ramipril, cilazapril, fosinopril, lisinopril, quinapril, etc.
Low dose diuretics: hydrochlorothiazide (< 25 mg/day) or potassium/ magnesium sparing diuretics such as amiloride and spironolactone should be used

Acceptable drugs include:

Angiotensin receptor blockers (ARBs) which are similar to ACE inhibitors in their hemodynamic action. They can be used singly or in combination, with the exception mentioned below. As with ACE inhibitors, ARBs are acceptable in pilots who have been on one of these medications for a month or more without any adverse effects.

Drugs that are not permitted include:

Sympatholytics: guanethidine, most alpha blockers
High dose kaliuretic diuretics (> 25 mg hydrochlorothiazide or equivalent).
Clonidine and methyldopa (because of a risk of rebound hypertension if these medications are inadvertantly not taken).
The combination of a nondihydropyridine calcium channel blocker with a beta-blocker.
The combination of an ACE with an ARB in those with coronary disease.

Combination treatment, eg a low dose diuretic with an ACE inhibitor may be allowed particularly as small doses of medications in combination may lead to fewer adverse effects than larger doses of single agents.

Multiple Risk Factors

Coronary atherosclerosis is a multifactorial disease, the risk of early onset increasing with the number of risk factors present. Therefore the assessment of risk must weigh appropriately the contribution of the various factors present. The cumulative risk conferred by the presence of more than one risk factor, even at levels only moderately above normal, can exceed that conferred by the presence of one major risk factor alone. The presence of only moderately elevated levels of risk when any risk factor is assessed alone should not lead to a false sense of security.

If the 10 year risk score is 20% or greater (9 risk points for men and 15 risk points for women, Table 2) or if diabetes or left ventricular hypertrophy are present, then a cardiovascular assessment including an exercise treadmill test should be carried out. Additional tests will depend on the risk factor profile. If abnormalities are found, resulting in an average annual mortality risk of 1% or more, assuming an additional 1% risk of an incapacitating nonfatal event, then a licence holder is considered medically unfit for an unrestricted licence. Even if the response to exercise testing is normal, appropriate therapy to modify risk factors should be initiated.

Global Risk

Using the Framingham risk scoring system, total risk can be assessed on the basis of risk points for age, total and HDL cholesterol, systolic blood pressure and smoking status in the absence of existing coronary heart disease or diabetes. Table 2. In order to use the scoring system, cholesterol determinations are necessary. While a global risk assessment may not be required of all pilots, obesity particularly in the midline, an abnormal resting ECG or other factors raising concern about possible coronary disease should result in a global assessment of risk.

The presence of either existing coronary heart disease or diabetes places the individual applicant in a potentially high risk category, thus warranting further investigation.

Table 2 - 10-Year Absolute Risk of CVD Event

RISK FACTOR	MEN	WOMEN	SCORE
Age (years)
<34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74	-1 0 1 2 3 4 5 6 7	-9 -4 0 3 6 7 8 8 8		__
Total cholesterol (mmol/L)
<4.14 4.15-5.17 5.18-6.21 6.22-7.24 >7.25	-3 0 1 2 3	-2 0 1 2 3		__
HDL cholesterol (mmol/L)
<0.90 0.91-1.16 1.17-1.29 1.30-1.55 >1.56	2 1 0 0 -2	5 2 1 0 -3		__
Systolic blood pressure (mmHg)
<120 120-129 130-139 140-159 >1.60	0 0 1 2 3	-3 0 1 2 3		__
Smoker
No Yes	0 2	0 2		__

Total Risk Points ____ (in individuals who have not had a prior CVD event)
Risk Points		1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17
Chd	Men	3	4	5	7	8	10	13	16	20	25	31	37	45	53
Risk	Women	2	3	3	4	4	5	6	7	8	10	11	13	15	18	20	24	>27

Chapter 2: Structural Heart Disease

Valvular Heart Disease

The significance of valvular heart disease depends primarily on the hemodynamic consequences, functional status and in some cases, the etiology of the valve disease. In the majority of cases, surgical correction will not reduce the risk of sudden incapacitation to acceptable levels; in some cases it may even increase the risk.

Aortic Stenosis

Moderate or severe stenosis is unacceptable for unrestricted flying. Applicants with mild stenosis of the aortic valve can be considered for licensure if the following conditions are met:

The transvalvular flow velocity across the valve is not more than 3 m/sec.
The cross-sectional valve area is not less than 1.2 cm², taking into account the individual’s body size.
Left ventricular systolic function is normal
There are no related symptoms.
Holter monitoring reveals no significant dysrhythmia such as uncontrolled atrial fibrillation or sustained ventricular tachycardia.
A satisfactory treadmill exercise test, to a minimum of 8.5 METS using the Bruce protocol indicates no ischemia, hypotensive blood pressure response, significant arrhythmia or disabling symptoms.

Aortic Regurgitation

Pure isolated regurgitation is uncommon; therefore, assessment of applicants with aortic regurgitation will likely include consideration of any associated disorders such as an abnormality of the valve leaflets or aortic root. Individuals with no more than mild to moderate, asymptomatic aortic regurgitation can be considered if the following criteria are met:

The pulse pressure is less than 70 mmHg and the diastolic pressure is greater than 65 mmHg.
Left ventricular systolic function is normal
The end-diastolic internal diameter of the left ventricle is less than 57 mm and the end-systolic internal diameter is less than 40 mm, taking into account the individual’s body size, as measured by two-dimensional echocardiography.
A satisfactory treadmill exercise test, to a minimum of 8.5 METS indicates no ischemia, significant arrhythmia or disabling symptoms.

Follow-up for Aortic Valve Disease

Follow-up should include a yearly assessment with comprehensive 2-D and Doppler echocardiography to monitor for disease progression.

Mitral Stenosis

In view of its progressive nature and propensity for atrial fibrillation and thromboembolic complications, most applicants with mitral stenosis are medically unfit. Only those with very mild mitral stenosis including a cross sectional mitral valve area > 2.0 cm² and stable normal sinus rhythm may be considered.

Mitral Regurgitation

The etiology of mitral regurgitation can alter the prognosis; therefore, an assessment of this condition should include information about the likely underlying cause, in addition to an estimate of the severity of the lesion. Asymptomatic mitral regurgitation of less than moderate severity may be acceptable in applicants if the following conditions are met:

Mitral stenosis is absent.
The diameter of the left atrium is less than 4.5 cm.
Left ventricular systolic function is normal
Atrial dysrhythmia such as atrial fibrillation/flutter or a sustained supraventricular tachycardia are absent, as determined by Holter monitoring.
There is no history of embolism.
The probability of significant coronary artery disease is low based on the results of a submaximal treadmill exercise test.

Mitral Valve Prolapse

Mitral valve prolapse has a wide spectrum of severity. Most cases are mild and detectable either by the presence of a midsystolic click and/or a soft murmur. The diagnosis is established by echocardiography. Medical certification may be considered if the following conditions are met:

There is no history of embolism or transient cerebral ischemia.
There is no relevant family history of sudden death.
Mitral regurgitation, if present, is less than moderate in severity.
The left ventricular end-diastolic size does not exceed 60 mm.
Left ventricular systolic function is normal.

If the left atrial size is increased or if there is redundancy of the mitral valve leaflets, then a treadmill exercise test and 24 hour Holter-monitoring will be required as these findings can be markers of increased risk.

Follow-up for Mitral Valve Disease

Annual follow-up for mitral valve stenosis should include a thorough history and physical examination, comprehensive 2D and doppler echocardiogram and 24 hour Holter monitoring. For mitral regurgitation, annual follow-up should include a through history, physical examination and comprehensive 2D and doppler echocardiogram. The follow-up for mitral valve prolapse will be determined on a case-by-case basis depending on the degree of prolapse and any associated findings.

Surgical repair or replacement of valves

The prosthetic or repaired valve must be functioning satisfactorily with no significant regurgitation (less than moderate). Left ventricular function (EF) must be at least 50% and individuals should have an exercise tolerance of at least 8.5 METS with no inducible ischemia. There must be no incapacitating arrhythmias. Those taking anticoagulants must demonstrate well-managed therapeutic INRs. Other factors such as the condition of other non-replaced valves, vascular changes i.e. aortic dilatation, history of endocarditis, thromboembolism etc will require evaluation on a case by case basis.

In view of the risk of thromboembolism, valve failure endocarditis and bleeding secondary to anticoagulation, prosthetic valvular replacement will disqualify most applicants. Where the cumulative risk of incapacitation due to these factors can be shown to be less than 2% per year and thus comparable to the acceptable level of risk with other conditions, an applicant may be considered medically fit.

Special procedures including the Ross procedure and homograft valve replacements will be considered on a case by case basis. The former requires a waiting period of at least 12 months to rule out pulmonary stenosis as a complication.

Following surgical reconstruction (valvuloplasty) of the mitral valve, a licence holder may be considered medically fit to fly if an assessment after 3 months including an echocardiogram indicates no clinically significant residual hemodynamic abnormalities, the presence of sinus rhythm and no incapacitating arrhythmias.

Congenital Heart Disease

Atrial septal defect

Applicants with a patent foramen ovale or a small sinus venosus or secundum defect (pulmonary/ systemic flow ratio less than 2:1 and normal right heart pressures) as determined by doppler echocardiography or cardiac catheterization and without recurrent atrial arrhythmias need not be restricted from flying. Applicants with partial atrioventricular canal defects (primum type atrial septal defects) cannot have more than mild mitral regurgitation, and they must meet the same requirements for flow ratios and atrial arrhythmias.

Those who have undergone a transcutaneous correction or a surgical correction of a larger defect may be medically certified if 3 months after the procedure they meet the same requirements, provided there has not been a significant event associated with their defect. A post-operative follow up echocardiographic evaluation is required to determine the extent of any residual leakage and shunting.

Coarctation of the Aorta

Licence holders with surgically corrected coarctation of the aorta should be considered individually. The age at the time of the surgical correction will be a major determinant in the decision about medical certification of a licence holder since the risk of sudden death and incapacitation due to cerebrovascular accidents is markedly increased in people who undergo surgery after the age of 12 years. In all cases the blood pressure at rest and in response to exercise must be normal.

Pulmonary Stenosis

The major determinant of risk in applicants with this condition is the severity of the stenosis. Those with mild pulmonary stenosis and normal cardiac output will be considered for licensure provided the following criteria are met:

The peak systolic pressure gradient across the pulmonary valve is less than 50 mmHg, and the peak systolic right ventricular pressure is less than 75 mmHg, as determined by echocardiography or cardiac catheterization.
Symptoms are absent.
The result of a submaximal treadmill exercise test is normal.

Applicants with pulmonic stenosis corrected by surgery or balloon valvuloplasty will be considered fit if there is no dysrhythmia and if the hemodynamic parameters are not worse than those described above.

Ventricular Septal Defect

An applicant's eligibility for medical certification will depend on the size of the ventricular septal defect as indicated by the hemodynamic consequences. In the absence of surgical correction an applicant may be considered for licensure if the following conditions are met:

The heart size is normal.
The pulmonary/systemic flow ratio is less than 2:1, as determined by echocardiography or cardiac catheterization.
The pressures in the right heart are normal.

An applicant with a surgically corrected ventricular septal defect may be considered for medical certification if the same conditions are met as for no surgical intervention, and in addition:

No dysrhythmias or high-grade conduction disturbances are detected by Holter monitoring.
The response to a submaximal treadmill exercise test is normal.

Tetralogy of Fallot

The unoperated condition with cyanosis is incompatible with medical certification. Individuals who undergo repair of Tetralogy of Fallot may be considered for medical certification if the following conditions are met:

Normal arterial oxygen saturation.
Normal heart size.
Right ventricular systolic pressure less than 75 mmHg and peak RV/PA gradient less than 50 mmHg.
Residual interventricular shunt not more than 1.5:1.
No dysrhythmias or high-grade conduction disturbances by Holter monitoring.
Normal performance on a treadmill exercise test.

Transposition of Great Arteries

The unoperated condition is incompatible with medical certification with the sole exception of congenitally corrected transposition without any other associated cardiac abnormalities.

Applicants with atrial switch corrective procedures for transposition of the great arteries are unlikely to be eligible for medical certification because of the increasing propensity to atrial arrhythmias with passing years, even with technically excellent surgery. Applicants who have had arterial switch operations will need to be considered separately when this cohort begins to reach adulthood.

Inflammatory Heart Disease

Active pericarditis and/or myocarditis are medically disqualifying. Medical certification may be considered after satisfactory recovery with no adverse sequelae.

Cardiomyopathy

Obstructive hypertrophic cardiomyopathy poses a significant risk for sudden incapacitation and generally renders an applicant medically unfit to fly even if there has been surgical treatment. Applicants with minor asymmetric hypertrophy will be considered individually based on the degree of outflow obstruction and the nature of any arrhythmias.

Nonhypertrophic cardiomyopathies dilated or congestive, in their active phase disqualify an applicant from flying. Symptomatic heart failure even with normal quantification of left ventricular function is incompatible with safe
piloting. Cardiac catheterization is usually required to rule out ischemia as the etiology of the cardiomyopathy. Recertification may be considered after recovery if the following conditions are met:

Symptoms are absent.
A satisfactory exercise tolerance test to a minimum of 8.5 METS, using the Bruce protocol indicates no ischemia, significant arrhythmia or disabling symptoms.
Left ventricular function as determined by echocardiography is satisfactory, i.e. EF > 50%. An ejection fraction between 40% and 50% may be acceptable for restricted flying provided 24 hour Holter monitoring reveals no more than 3 ventricular ectopic beats per hour in the absence of antiarrhythmic medication, with no more than 3 consecutive beats and a cycle length of not less than 500 msec. Nonsustained ventricular tachycardia in someone with an ischemic cardiomyopathy is not acceptable.
The risk of thromboembolism and (if applicable) the risk of hemorrhage secondary to anticoagulation is acceptable.

Cardiac Transplantation

Due to the cumulative high rate of morbidity including the insiduous progression of coronary disease and an increasing mortality rate over time, applicants are unlikely to be medically fit to fly unrestricted following cardiac transplantation. Experienced pilots with a low grade of rejection, no evidence of coronary ischemia and satisfactory control of modifiable risk factors may be considered medically fit for restricted flying.

Chapter 3: Arrhythmias and Devices

All applicants with dysrhythmias should be evaluated with two questions in mind: what is the nature of the disability produced by a given arrhythmia i.e., how incapacitated is the applicant when the dysrhythmia occurs? and what is the underlying condition of the heart? i.e., is structural heart disease present? Both questions must be answered before a decision can be made about medical fitness to fly.

Supraventricular Dysrhythmias

Supraventricular tachydysrhythmias may accompany self-limited illnesses e.g., pneumonia or treatable conditions e.g. hyperthyroidism. In such cases, the need to restrict flying will be only temporary.

Applicants in whom treatment with an antiarrhythmic agent is successful need not be restricted from flying. Given the high rate of success with ablation therapy, individuals may be considered medically fit one month after the procedure. Applicants who undergo AV nodal ablation of the slow pathway are more likely to be reconsidered favourably because of the lower risk of development of heart block.

Sinus Node Dysfunction

Isolated sinus node dysfunction including sinus bradycardia may occur in healthy people, particularly those involved in vigorous exercise programs. Such a finding (a consequence of high vagal tone) need not necessarily be considered an abnormality. Provided the dysfunction does not interfere with mental function, the licence holder need not be restricted from flying. Where there is concern e.g. extreme bradycardia, a thorough symptom history should be followed by Holter monitoring and a treadmill exercise test. Even in a healthy applicant, no R-R interval should exceed 4 sec during sleep or 3 sec while awake.

Atrial Fibrillation/Flutter

There are 3 major concerns in the assessment of the risk of incapacitation in an individual with atrial fibrillation or flutter. The first is the hemodynamic effect of the arrhythmia itself. The second is the risk of embolism and the third is the risk of bleeding as a consequence of anticoagulation. Since risk is additive, the aggregate risk must remain within acceptable limits. Therefore it is possible that selected aircrew may be considered medically fit depending on their condition and the effect of treatment.

Ablation therapy is increasingly used for atrial flutter and is highly successful (98%). Such individuals can be considered medically fit within a month of the procedure. Ablation therapy is less successful (80% with up to 2 procedures) in those with atrial fibrillation. An assessment should take place at 3 and 6 months following ablation for atrial fibrillation.

The risk of thromboembolism can be assessed using the CHADS2 scoring system, recognizing that risk increases with increasing age. The lowest risk is seen in those below 75 years of age who have intermittent or chronic, lone atrial fibrillation, i.e. no identifiable cause of the arrhythmia and no underlying structural heart disease. Annual follow-up in such cases should include 24 hr Holter monitoring. Individuals with atrial fibrillation who have 2 or more of the 5 major risk factors, including age >75 years, structural heart disease, diabetes, high blood pressure and previous thromboembolism are considered to be above the threshold level of risk (5%) even when fully anticoagulated. Anticoagulation carries a bleeding risk that is increased with factors such as previous bleeding, hypertension and age > 75 years and can be estimated with the HEMORR2HAGES score. Thus, older licence holders with structural heart disease generally have a cumulative risk of embolism and bleeding secondary to anticoagulation that exceeds the limit for medical fitness. The introduction of newer anticoagulants with the same or better efficacy than coumadin but with less bleeding risk may improve the cumulative risk for some individuals.

Pre-Excitation Syndromes

Not all cases of Wolff-Parkinson-White (the most common type of pre-excitation) are associated with incapacitating dysrhythmias. The risk of incapacitating symptoms in people who have never had tachycardia is low but is not known with any precision. Applicants with only an electrocardiographic indication, whether chronic or intermittent, and no history of palpitations may be fit to fly if their response to a treadmill exercise test is normal in all respects particularly if evidence of preexcitation is lost at accelerated heart rates. Such individuals are unlikely to conduct at a dangerously high rate if in atrial fibrillation. Electrophysiologic studies are not required in such cases.

Medical certification in a restricted capacity may be considered 3 months after a symptomatic episode of tachycardia has been controlled with medication. Applicants in whom accessory pathway connections have been ablated surgically or by catheter techniques are considered medically fit if at 3 months they are asymptomatic and their electrocardiogram shows no evidence of pre-excitation. In some cases a treadmill stress test or repeat electrophysiologic studies may be required 3 months after surgery to confirm a successful intervention.

Ventricular Dysrhythmias

The main concern with ventricular dysrhythmias is the underlying condition of the myocardium. A careful assessment should be done to determine the presence of structural heart disease. If the myocardium is normal, ventricular ectopy should be judged on the basis of the disability produced and, to a lesser extent, on the presence or absence of complex forms. Although the complexity of premature ventricular beats is poorly correlated with risk in the presence of normal myocardial tissue, the appearance of multiform or repetitive forms of ventricular ectopy i.e., couplets, runs, should indicate the need for a thorough cardiac examination since these and other high grade forms of ectopy are more commonly seen in association with structural heart disease. If the ventricular ectopic beats have a LBBB pattern particularly with a vertical axis, right ventricular dysplasia should be ruled out by either invasive (ventriculography) or non-invasive (echo, MRI or radionuclide scintigraphy) tests.

In the presence of one or more PVCs on a resting 12-lead electrocardiogram, consideration should be given to an echocardiographic study and/or 24 hour Holter monitoring.

Exercise-induced ventricular tachycardia can occur in healthy people. These events are usually selfterminating. Medical certification need not be restricted in such cases unless there are recurrent episodes. Individuals with sustained tachycardias are unfit.

Electrocardiographic findings suggesting Brugada’s syndrome, in the absence of symptoms and a family history of arrhythmias or sudden death do not require any restriction.

Conduction Disorders

First-and-second-degree (type 1) atrioventricular conduction delay can be seen during rest (particularly sleep) in healthy people with a structurally normal heart who engage in vigorous exercise. High grade atrioventricular block should be investigated to rule out heart disease and to determine the risk of progression to complete heart block. Likewise first and second-degree block with structural heart disease should be investigated to determine the risk of progression to complete heart block.

Bundle Branch Block

Left bundle branch block and right bundle branch block of recent onset, indicate the need for a cardiovascular examination to rule out heart disease, especially ischemic heart disease. Isolated right bundle branch block and left hemiblocks that are longstanding are generally benign.

Cardiac Pacemakers

The reliability and safety of implantable cardiac pacemakers is well established and continues to improve. In determining medical fitness, consideration must be given to the presence of any structural heart disease. Given the high degree of reliability of modern pacemaker systems, even pacemaker dependency need not restrict a pilot if the risk of failure is less than 2% /year. Each case will need to be considered individually and not before 3 months after successful implantation. Factors to be taken into consideration include potential environmental interference (low risk in cockpits today), device recalls and estimated battery longevity. Follow up for those with a pacemaker, which should take place every 6 months, requires a pacemaker clinic report including an indication of the underlying rhythm and escape rate.

Implanted Cardiac Defibrillators

It is highly improbable that an individual with an implanted cardiac defibrillator can be considered fit. However individual cases can be considered provided there is no structural heart disease and even in such cases only a restricted medical certification may be granted. Such restricted certification will not be considered before completion of a trial period of at least 6 months. During this time defibrillator function and cardiac response must be carefully monitored to ensure that any dysrhythmias are properly identified and promptly corrected without any incapacitation, and that there are no inappropriate shocks.

Chapter 4: Vascular Disorders

Dilated Ascending Aorta or Thoracic Aortic Aneurysm

The natural history of a dilated thoracic aorta and the risk of an incapacitating event such as aortic dissection or rupture is dependent on the specific etiology (degenerative disease, genetically mediated disease etc.), size of the aorta, rate of growth and individual body size among other factors. Individuals with a dilated aorta need to be evaluated on a case by case basis, but may be eligible for medical certification if the risk of rupture or dissection can be demonstrated to be less than 2% per year. Individuals with a bicuspid aortic valve and ascending aorta less than 45 mm in size, taking into account the individual’s body size, with no family history of sudden death, aortic dissection or rupture may be eligible for medical certification. Annual follow-up is required and should include imaging of the dilated aorta.

Abdominal Aortic Aneurysm

Untreated aneurysms, even if asymptomatic are unlikely to be compatible with medical certification unless it can be demonstrated that the risk of rupture is less than 2% per year. Such low risk is associated with an aneurysmal size of less than 5 cm, the acceptable threshold being 4.5 cm.

The presence of an abdominal aneurysm in a middle-aged or older pilot raises concerns about the presence of co-existing conditions, particularly coronary artery disease. Modifiable risk factors particularly those which raise the risk of rupture such as hypertension must be controlled. Smoking must be eliminated. Prosthetic graft replacement of diseased aortic aneurysms with no other evidence of risk will be considered on an individual basis.

Asymptomatic Carotid Bruit

Since the presence of a carotid bruit may indicate severe stenosis, it should lead to a carotid doppler examination. Likewise a cardiovascular assessment is required to rule out significant coronary artery disease. Significant stenosis (>75%) even asymptomatic is associated with a >33% risk of coronary events over 4 years and therefore renders the applicant unfit. Any stenosis that has been associated with a stroke or TIA will also make the applicant medically unfit.

Arterial Thrombosis

Individuals who have sustained an isolated, arterial thrombosis will be considered on an individual basis. Of particular concern are thromboses related to coagulopathies or other chronic predisposing conditions.

Venous Thrombosis

An isolated episode of deep venous thrombosis need not preclude medical certification provided there are no chronic predisposing conditions, and a minimum of 3 months have elapsed since the episode. Applicants with recurring episodes or with known predisposing factors will be considered on an individual basis only after 12 months have elapsed since the last episode and their risk of recurrence is lowered by satisfactory anticoagulation. In such cases pilots will be considered for a restricted category. The latter requires demonstration of at least two therapeutic INR levels over a recent 1 month period.

Pulmonary Embolism

Applicants with an isolated episode of pulmonary embolism, without predisposing conditions for recurrence can be considered for relicensure after an interval of 3 months, provided there is no disabling, residual pulmonary hypertension, right ventricular function is normal and the risk of venous thrombosis and pulmonary embolism is decreased by appropriate treatment to an acceptable level.

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Mitral Regurgitation

Avierinos JF, Gersh BJ, Melton LJ 3rd, et al. Natural history of asymptomatic mitral valve prolapse in the community. Circulation 2002;106:1355-1361.

Enriquez-Sarano M, Avierinos JF, Messika-Zeitoun D, et al. Quantitative determinants of the outcome of asymptomatic mitral regurgitation. N Engl J Med 2005;352:875-883.

Freed LA, Levy D, Levine RA, et al. Prevalence and clinical outcome of mitral-valve prolapse. N Engl J Med 1999;341:1-7.

Gilon D, Buonanno FS, Joffe MM, et al. Lack of evidence of an association between mitral-valve prolapse and stroke in young patients. N Engl J Med 1999;341:8-13.

Grigioni F, Enriquez-Sarano M, Zehr KJ, et al. Ischemic mitral regurgitation: long-term outcome and prognostic implications with quantitative Doppler assessment. Circulation 2001;103:1759-1764.

Kim S, Kuroda T, Nishinaga M, et al. Relation between severity of mitral regurgitation and prognosis of mitral valve prolapse: echocardiographic follow-up study. Am Heart J 1996; 132:348-355.

Lamas GA, Mitchell GF, Flaker GC, et al. Clinical significance of mitral regurgitation after acute myocardial infarction. Circulation 1997; 96:827-833.

Marks AR, Choong CY, Sanfilippo AJ, et al. Identification of high-risk and low-risk subgroups of patients with mitral-valve prolapse. N Engl J Med 1989;320:1031-1036.

Zuppiroli A, Rinaldi M, Kramer-Fox R, et al. Natural history of mitral valve prolapse. Am J Cardiol 1995;75:1028-1032.

Pulmonary Stenosis

Hayes CJ, Gersony WM, Driscoll DJ, et al. Second natural history study of congenital heart defects: results of treatment of patients with pulmonary valvular stenosis. Circulation 1993;87[Suppl I]:I- 28-I-37.

Prosthetic Valves

Fann JI, Burdon TA. Are the indications for tissue valves different in 2001 and how do we communicate these changes to our cardiology colleagues? Curr Opin Cardiol 2001; 16:126-135.

Fann JI, Miller DC, Moore KA, et al. Twenty-year clinical experience with porcine bioprostheses. Ann Thorac Surg 1996;62:1301-1312.

Glower DD, Landolfo KP, Cheruva S, et al. Determinants of 15-year outcome with 1119 standard Carpentier-Edwards porcine valves. Ann Thorac Surg 1998;66:S44-48.

Grunkemeier GL, Wu Y. “Our complication rates are lower than theirs": statistical critique of heart valve comparisons. J Thorac Cardiovasc Surg 2003;125:290-300.

Jamieson WR, Burr LH, Munro AI, et al. Carpentier- Edwards standard porcine bioprosthesis: a 21-year experience. Ann Thorac Surg 1998; 66:S40-43.

Jamieson WR, von Lipinski O, Miyagishima RT, et al. Performance of bioprostheses and mechanical prostheses assessed by composites of valve-related complications to 15 years after mitral valve replacement. J Thorac Cardiovasc Surg 2005;129:1301-1308.

Park SZ, Reardon MJ. Current status of stentless aortic xenografts. Curr Opin Cardiol 2000; 15:74-81.

Puvimanasinghe JPA, Steyerberg EW, Takkenberg JJM, et al. Prognosis after aortic valve replacement with a bioprosthesis: predictions based on meta-analysis and microsimulation. Circulation 2001;103:1535-1541.

Remadi JP, Baron O, Roussel C, et al. Isolated mitral valve replacement with St. Jude medical prosthesis: long-term results: a follow-up of 19 years. Circulation 2001;103:1542-1545.

Stein PD, Bussey HI, Dalen JE, et al. Antithrombotic therapy in patients with mechanical and biological prosthetic heart valves. Chest 2001;119:220S-227.

Vongpatanasin W, Hillis D, Lange RA. Prosthetic heart valves. N Engl J Med 1996;335:407-416.

Aortic Allograft Replacement

Doty JR, Salazar JD, Liddicoat JR, et al. Aortic valve replacement with cryopreserved aortic allograft: ten-year experience. J Thorac Cardiovasc Surg 1998;115:371-380.

Kirklin JK, Smith D, Novick W, et al. Long-term function of cryopreserved aortic homografts: a ten-year study. J Thorac Cardiovasc Surg 1993; 106:154-166.

O'Brien MF, Stafford EG, Gardner MAH, et al. Allograft aortic valve replacement: long-term follow-up. Ann Thorac Surg 1995;60:565-570.

Ross Procedure

Takkenberg JJ, Klieverik LL, Schoof PH, et al. The Ross Procedure: a systematic review and meta-analysis. Circulation 2009;119:222-228.

Transposition

Ikeda U, Kimura K, Suzuki O et al. Long-term survival in "corrected transposition. Lancet 1991; 337:180-181.

Mitral Valve Repair

Bernal JM, Rabasa JM, Olalla JJ, et al. Repair of chordae tendinae for rheumatic mitral valve disease: a twenty year experience. J Thorac Cardiovasc Surg 1996;111:211-217.

Braunberger E, Deloche A, Berrebi A, et al. Very long-term results (more than 20 years) of valve repair with Carpentier's techniques in nonrheumatic mitral valve insufficiency. Circulation 2001;104[Suppl I]:I8-11.

Chauvaud S, Fuzellier J-F, Berrebi A, et al. Longterm (29 years) results of reconstructive surgery in rheumatic mitral valve insufficiency. Circulation 2001;104[Suppl I]:I12-15.

Gillinov AM, Cosgrove DM, Blackstone EH, et al. Durability of mitral valve repair for degenerative disease. J Thorac Cardiovasc Surg 1998;116: 734-743.

Hausmann H, Siniawski H, Hotz H, et al. Mitral valve reconstruction and mitral valve replacement for ischaemic mitral insufficiency. J Cardiac Surg 1997;12:8-14.

Mohty D, Orszulak TA, Schaff HV, et al. Very longterm survival and durability of mitral valve repair for mitral valve prolapse. Circulation 2001; 104[Suppl I]:I1-7.

Obadia JF, Farra ME, Bastien OH, et al. Outcome of atrial fibrillation after mitral valve repair. J Thorac Cardiovasc Surg 1997;114:179-185.

Suri RM, Schaff HV, Dearani JA, et al. Survival advantage and improved durability of mitral repair for leaflet prolapse subsets in the current era. Ann Thorac Surg 2006;82:819-826.

Yau TM, El-Thoneimi YAF, Armstrong S, et al. Mitral valve repair and replacement for rheumatic disease. J Thorac Cardiovasc Surg 2000;119:53-61.

Aortic Valve Repair

Boodhwani M, de Kerchove L, Glineur D, et al. Repair-oriented classification of aortic insufficiency: impact on surgical techniques and clinical outcomes. J Thorac Cardiovasc Surg 2009;137:286-294.

Percutaneous Mitral Balloon Valvuloplasty

Hernandez R, BaZuelos C, Alfonso F, et al. Longterm clinical and echocardiographic follow-up after percutaneous mitral valvuloplasty with the Inoue balloon. Circulation 1999;99:1580-1586.

Iung B, Garbarz E, Michaud P, et al. Late results of percutaneous mitral commissurotomy in a series of 1024 patients: analysis of late clinical deterioration: frequency, anatomic findings, and predictive factors. Circulation 1999;99: 327 2-3278.

Orrange SE, Kawanishi DT, Lopez BM, et al. Actuarial outcome after catheter balloon commissurotomy in patients with mitral stenosis. Circulation 1997;95:382-389.

Palacios IF, Tuzcu ME, Weyman AE, et al. Clinical follow-up of patients undergoing percutaneous mitral balloon valvotomy. Circulation 1995; 91:671-676.

Percutaneous Pulmonary Balloon Valvuloplasty

Chen CR, Cheng TO, Huang T, et al. Percutaneous balloon valvuloplasty for pulmonic stenosis in adolescents and adults. N Engl J Med 1996; 335:21-25.

Jarrar M, Betbout F, Ben Farhat M, et al. Long-term invasive and noninvasive results of percutaneous balloon pulmonary valvuloplasty in children, adolescents and adults. Am Heart J 1999; 138:950-954.

Rao PS, Galal O, Patnana M et al. Results of three to 10 year follow up of balloon dilation of the pulmonary valve. Heart 1998;80:591-595.

Sadr-Ameli MA, Sheikholeslami F, Firoozi et al. Late results of balloon pulmonary valvuloplasty in adults. Am J Cardiol 1998;82:398-400.

Arrhythmias and Devices

Calkins H. Catheter Ablation for Cardiac Arrhythmias. Med Clinics of N America. 2001;85:473-502.

Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC 2006 Guidelines for the management of patients with atrial fibrillation a report of the American College of Cardiology/American Heart Association Task Force on practice guidelines and the European society of cardiology committee for practice guidelines. J Am Coll Cardiol 2006;148: e149–e246.

Gage BF, Yan Y, Milligan PE et al. Clinical classification schemes for predicting hemorrhage: results from the national registry of atrial fibrillation (NRAF). Am Heart J. 2006;151:713-719.

Gould PA, Krahn AD, for the Canadian Heart Rhythm Society Working Group on Device Advisories. Complications associated with implantable cardioverter-defibrillator replacement in response to device advisories. JAMA 2006; 295:1907-1911.

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incidence, prevalence, and prediction of stroke using the Congestive heart failure, Hypertension, Age >75, Diabetes mellitus, and prior Stroke or transient ischemic attack (CHADS2) risk stratification scheme. Am Heart J 2008;156:57– 64.

Vascular Disorders

Chandra D, Parisini E, Mozaffarian D. Meta-analysis: travel and risk for venous thromboembolism. Ann Intern Med 2009;151:180-190.

Chimowitz MI, Weiss DG, et al. Cardiac prognosis of patients with carotid stenosis and no history of coronary artery disease, Stroke 1994; 25: 759-765.

Davies RR, Gallo A, Coady MA, et al. Novel Measurement of Relative Aortic Size Predicts Rupture of Thoracic Aortic Aneurysms. Ann Thorac Surg 2006;81:169 –177.

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Goldhaber SZ. Risk factors for venous thromboembolism. J Am Coll Cardiol 2010; 56:1-7.

Diabetes

Introduction

In 1923, Dr. Banting and Dr. Best discovered insulin and this revolutionized the treatment of diabetics. Insulin permitted many diabetics to live full functional lives.

In April 1992, a one-day workshop was held in Ottawa to review the medical treatment of diabetics in the context of the modern aviation environment. Guidelines were developed based on the deliberations at that meeting.

The diagnosis and control of this condition continues to improve dramatically, allowing an individualized approach to care and follow-up. The more recent advances in the use of glucose meters with memory chips, and the introduction of advanced insulins and drugs permit the increasingly more precise control of blood glucose. The data permit more individualized therapies consisting of diet, exercise, adjustment of medication regimens and standardized follow up.

This sophisticated progress in the medical care of diabetics prompted Transport Canada's Civil Aviation Medicine (CAM) Branch to re-examine its policies on diabetes mellitus. An expert panel once again convened to review and to assess the most recent research. The new aeromedical guidelines were revised, where appropriate, with consideration of the Canadian Diabetes Association 2013 guidelines. This document reflects not only the consensus opinion of aviation and diabetes specialists in Canada but also includes the deliberations from other international diabetes panels that have convened in the past year.

These Guidelines are provided as a source of guidance to Civil Aviation Medicine Examiners (CAME). Whilst every effort is made to maintain the currency of these Guidelines, changes in medical science or clinical practice after time of publication may impact on the accuracy of these Guidelines and CAM gives no assurance as to the accuracy of them.

The Guidelines are not a statement about how CAM will proceed to make a decision in every case. Instead, they highlight to CAME's the likely areas of importance for certain safety-relevant conditions, and to inform the timely collection of appropriate information. CAM makes aeromedical decisions on a case by case basis. A particular assessment decision is based on the individual circumstances of the applicant under consideration.

Physicians are reminded that this document should be used as a guide only and it should not be confused with the medical standards for aviation personnel published in the Canadian Aviation Regulations (Standard 424 - Medical Requirements). Any specific questions should be directed to the nearest regional aviation medical office of the Civil Aviation Medicine Branch, Transport Canada.

If reading a printed copy, please ensure that the copy is the current version by checking the website.

Note: All ITDM (Insulin Treated Diabetes Mellitus) applicants who have achieved medical certification will be monitored by a single physician within the CAM organization in order to maintain consistency and an adequate data base.

AEROMEDICAL CONSIDERATIONS

The major consideration in the medical certification of diabetics is the risk of subtle or sudden incapacitation. For the diabetic, this risk comes in the short term from the extremes in blood sugar levels and in the longer term from vascular damage. Let us therefore consider the metabolic conditions associated with diabetes.

HYPOGLYCEMIA

Hypoglycemia refers to blood sugars outside the normal range, and although both hyper and hypoglycemia are a concern in aviation, hypoglycemia would most likely precipitate an incapacitation. Hypoglycemia is usually considered to be a blood glucose concentration in the range below the level at which symptoms could be expected to occur. In the person without diabetes, blood glucose is kept within a fairly narrow range by a homeostatic mechanism regulated by glucose intake and storage, insulin, glucagon, catecholamine, cortisol and growth hormone. In the diabetic, treated or not with medication, the fine control of this delicate homeostasis has been compromised. Hypoglycemia may result from too much insulin or insulin producing medication, too little glucose, an over-expenditure of energy or any combination of the above.

Diabetes specialists officially define hypoglycemia as being:

the development of neurogenic or neuroglycopenic symptoms (listed below);
a low plasma glucose level (<4.0 mmol/L for patients treated with insulin or an insulin secretagogue); and
symptoms responding to the administration of carbohydrate

The symptoms and signs of hypoglycemia can be broken down into two main groups:

Neurogenic
- Hunger
- Nervous
- Tachycardia
- Agitation
- Weakness
- Palpitations
- Tremor
- Sweating
Neuroglycopenic
- Cognitive impairment
- Mental status changes
- Abnormal behavior
- Irritability
- Dizziness, ataxia
- Vision Changes
- Difficulty Speaking
- Difficulty Concentrating
- Confusion
- Weakness
- Drowsiness
- Seizure activity

Of particular concern are the neuroglycopenic effects of hypoglycemia and the effect they have on information processing, obviously an extremely important aspect of both piloting and air traffic controlling tasks.

Results from multicentre trials reveal that the incidence of hypoglycemic reactions is more common among an intensively insulin treated group of patients with diabetes. The severity of the hypoglycemic reactions can vary with the more severe reactions being related to the degree of glycemic control and the effectiveness of the physiological counter regulatory mechanisms.

The blood glucose levels at which an individual may recognize hypoglycemia can vary as well and is believed to be lower in those whose diabetes has been of a longer duration. This is a result of blunting of the counter regulatory mechanisms and is commonly referred to as « hypoglycemia unawareness».

It is apparent then that the unpredictability of hypo or hyperglycemia could be a major aviation safety hazard in the cockpit or the air traffic control workplace.

Table 1 attempts to address the question of risk for hypoglycemia. Those diabetics treated with potentially hypoglycemic medications* who fall into the high risk group would generally not be considered for any form of license, whereas those falling in the low risk group could be considered.

Table 1 - Hypoglycemia Risk among Diabetics on potentially hypoglycemic medications

High Risk	Low Risk
Stimulated c-peptide levels < 25% normal** Previous hypoglycemic reactions requiring intervention Unstable glycaemia control as measured by: A1c > 10.0 Blood glucose metering values < 4.0 mmol/L Inadequate self monitoring Poor diabetes education and understanding Evidence of hypoglycemia unawareness Negative attitude to self care	No previous hypoglycemic reactions requiring intervention Stable control as measured by: A1c < 8.5) Number of blood glucose metering values > 5.0 mmol/L Adequate self monitoring with memory chip glucose meter Good diabetes education and understanding No evidence of hypoglycemia unawareness Positive attitude to monitoring and self care

* Potentially hypoglycaemic medication include sulfonylureas, gliptin type medications and most insulins although the longer acting analogue type insulins are considered as having a lower risk.

** C-peptide is an indicator of beta cell activity. Most Type 1 diabetics are C-peptide negative.

HYPERGLYCEMIA AND END ORGAN DAMAGE

The periodic medical assessment of all applicants has two main purposes. The first is to assess the functional ability of the pilot in order to ascertain whether he is physically able to exercise safely the privileges of his license in all routine and emergency situations. The second is to assess the risk of incapacitation during the period of validity of the medical certificate for which he has applied. This degree of risk should not be much in excess of the risk of the same condition occurring in a completely healthy person. In Canada, for conditions such as coronary events or seizure following head injury, a risk of 2% per annum or less for an incapacitation has been considered acceptable for an unrestricted license or permit.

The effects of diabetes on the heart, kidneys, eyes and brain (end organs) must be ascertained both in terms of functional ability and the total risk of incapacitation. Hyperglycemia (BS >15mmol/L) may in the short term negatively impact upon mood, insight or vision. The longer term effects on organ function have been well documented and are the drivers of monitoring and review.

Assessment and Surveillance considerations for applicants with Diabetes Mellitus (DM)

MEDICATION:
Applicants who require medications to control blood sugars should be on a stable dosage. For agents with a low hypoglycemic risk, the dose should be established and stable over a minimum of 3 months. For those who require agents at a higher risk of hypoglycemia, the established dose should be stable for a minimum of 6 months.

Insulin pumps for drug delivery may be authorized with a precaution for the risk of over delivery in the event of a rapid decompression.
HYPOGLYCEMIA:
For those who require agents at risk of hypoglycemia, documentation of any history of symptomatic or biochemical hypoglycemia in the preceding 12 months is required along with details of any ensuing intervention.
BLOOD GLUCOSE CONTROL
All applicants must provide evidence of stable blood glucose control for at least 3 months as measured by:
1. A1c (the result should approximate current diabetes guidelines and generally be between 6 and 8.5)
2. Blood glucose metering values ABOVE 3.5 mmol/L.
BLOOD GLUCOSE MONITORING
Blood glucose monitoring will be carried out using a memory chip glucometer (equipment must be verified for accuracy annually), together with a readily absorbable source of glucose, will be carried by the applicant while exercising the privileges of the licence.
NEUROLOGICAL OR RENAL COMPLICATIONS:
There should be no neurological or renal complications of DM that could result in sudden or subtle incapacitation while exercising the privileges of the licence. This determination should be provided annually and can be provided by the treating physician or CAME. Measurements of renal function such as eGFR and Albumin to Creatinine ratio's are encouraged.
VISION
A vision care specialist (ophthalmologist or optometrist) assessment is required on initial application and every year thereafter. There should be no evidence of significant diabetic retinopathy.
CARDIOVASCULAR
An assessment of cardiovascular risk will start at the time of diagnosis or the initial application and is required annually. This must include a lipid panel, blood pressure measurement and information on lifestyle management including smoking status. Screening tests for cardiovascular disease should commence after age 40. An exercise electrocardiogram reaching 8.5 METS on the Bruce protocol is the preferred exam but a CT calcium score may be acceptable. Although the periodicity for screening may be individualized, generally, the treadmill exercise test should be expected every two years. A routine ECG will be required on alternate years when the Exercise Stress Test is not required.
VALIDITY
The validity period of medical certification will be no greater than 1 year.

A template flow sheet for diabetes monitoring will be provided. It is recommended that the applicant maintain its currency and accuracy for ease of review at the time of the periodic aviation medical and the final assessment by Civil Aviation Medicine.

Appendix 1 - Insulin Treated Diabetics -Blood Glucose Management Prior to and During Flight Categories 1, 3, 4 Medical Certification Conditions

Note: Blood Glucose levels will be required to be maintained at higher than optimal values prior to and during flight, in order to minimize the risk of hypoglycemia. This may have an effect on the long term health of the individual. The applicant must be made fully aware of this.

Individuals treated with insulin shall maintain the appropriate supplies for blood glucose management, which shall include:
1. A reliable calibrated glucose meter with memory chip and appropriate blood sampling equipment.
2. A supply of 10 gm. portions of readily absorbable carbohydrate, appropriate to the duration of flight.
Prior to flight blood glucose must be greater than 6.0 mmol/L but not greater than 15 mmol/L within the 30 minutes prior to flight. Blood glucose must be monitored every 60 minutes during flight. If the blood glucose falls below 6.0 mmol/L then 10 gms. carbohydrate should be ingested.
If, for operational reasons, the in-flight 60 minute blood glucose measurement cannot be done, then 10 gms. Carbohydrate must be ingested; however, this shall not be done on two consecutive 60 minute occasions without a blood glucose measurement.
The blood glucose should be measured 30 minutes prior to landing and if below 6.0 mmol/L then 10 gms. carbohydrate must be ingested.
If the blood glucose should ever exceed 15 mmol/L during flight then there should be no further caloric intake until after retesting. Pilots should consult their Civil Aviation Medical Examiner or Aviation Medical Officer as soon as practicable to determine whether the condition might impair the ability to exercise the privileges of the licence safely. Those flying as a single pilot must land as soon as safely possible if the blood glucose should ever exceed 15 mmol/L.

Air Traffic Controllers must follow a similar protocol for glucose management with blood glucose testing occurring every 2 hours during working hours.

Appendix 2 - Risk Stratification and Management Framework

The conference group has proposed the following risk stratification and matrix approach in developing guidelines for the medical certification of pilots, air traffic controllers and flight engineers with diabetes. It must be understood that this matrix is intended as a general guide, as all factors will not necessarily carry equal weight and that each case will be reviewed individually.

Diagnostic Detail and Blood Sugar Control
	LOW	MODERATE	HIGH	VERY HIGH
A1C	6.0-7.0	7.1-8.5	8.6-10	>10
DISEASE DURATION (YEARS)	<5	5- 10	11 - 20	> 20
BLOOD SUGAR READINGS BELOW 4.0	None	None	Few	Many
BLOOD SUGAR READINGS ABOVE 18.0	None	Few	Many
PHARMACOLOGICAL TREATMENT	None or non hypo-glycemic	Basal, long acting insulins	Some oral agents (see above) other insulins	Multiple insulin dosing and combinations
HYPOGLYCEMIC EPISODES	None		Minor	Significant (requiring the intervention of another person)
TREATMENT ADHERENCE AND SELF MONITORING	V. Good	Good	Satisfactory	Poor

End Organ Effects
	LOW	MODERATE	HIGH	VERY HIGH
OPHTHALMOLOGICAL (RETINOPATHY)	None	Minor	Moderate	Advanced
NEUROLOGICAL (INCLUDING NEUROPATHY)	None	Mild	Moderate	Established (stroke or TIA)
RENAL ACR. eGFR (ML/MIN)	ACR < 2 eGFR> 60	ACR 2-20eGFR 30- 60	ACR 21-60eGFR 30- 59	ACR >60eGFR <30
CARDIOVASCULAR RISK (UKPDS RISK ENGINE)	Low	Moderate	High	Established(angina, mi, revascularization
TREATMENT ADHERENCE AND SELF MONITORING	V. Good	Good	Satisfactory	Poor

The highest level scored on any single row above will guide the applicant's overall diabetes risk assessment.

Individual factors, in conjunction with the framework table below, will affect the determination of the flying category allowed and any applicable restrictions.

Complex or higher risk applicants may be reviewed by the Aviation Medical Review Board.

Management Framework

	CAT1*	CAT 2	CAT 3	CAT 4
Low Risk:	Fit with annual reports	Fit with annual reports	Fit with annual reports	Fit with annual reports
Moderate risk	Restricted with co-pilot	Restricted with a 2nd controller	Fit with annual reports	Fit with annual reports
High risk	Restricted with co-pilot or unfit	Restricted with a 2nd controller	Fixed wing only Daylight only No passengers, or only 1 passenger Single Engine Not High Performance Aircraft	Fit with annual reports
Very high risk	Unfit	Unfit	Restricted with co-pilot or unfit	Restricted with co-pilot or unfit

In accordance with current TC policy, applicants with Insulin Treated Diabetes Mellitus may be assessed for medical certificates as follows.

Those who already hold a professional pilot licence (ATPL, CPL) may be considered for a Category 1 medical certificate, restricted to flying with an accompanying pilot, as well as for a Category 3 or 4 medical certificate

All other pilots will only be considered for a Category 3 or 4 medical certificate.

Date modified: 2015-02-20

References

Canadian Diabetes association
Supplement to CJD 2013; 161 (11 Suppl)

Appendix 1

STANDARD FOR CATEGORY 4
(Glider and Ultralight)

An unstable metabolic disorder in the case of diabetes mellitus shall include any of the following.

Any history within the past 2 years of hypoglycemia requiring the intervention of another person or hypoglycemia in the absence of warning symptoms (hypoglycemic unawareness).
Inadequate blood glucose control as indicated by blood glucose results or glycated hemoglobin results.
Significant visual, neurological or cardiovascular complications.

If an applicant with diabetes has none of the above, he/she may hold a Category 4 MC provided the following requirements are also met:

A full medical examination report, conducted by a designated CAME is submitted to the RAMO.
A full report from a specialist in Endocrinology or Internal Medicine is submitted to the RAMO at first application and at yearly intervals thereafter.

Appendix 2

AIR TRAFFIC CONTROLLERS (ATCS)

Permission by special flexibility may be granted to ATCs who have developed ITDM but are in the low risk group.

Glucose management during working hours:

All ITDM shall identify themselves as such to the shift supervisor. Individual ATCs with ITDM shall have appropriate medical supplies available at all times in the workplace.

Supplies shall include:

Blood glucose monitor with a memory chip.
Blood sampling lancets.
A source of readily absorbable glucose.
Insulin with syringes or pump.
>Blood glucose levels will be tested:
30 minutes prior to shift commencement.
Every 2 hours during shift.
If because of operational requirements the 2 hourly blood glucose cannot be done then the individual must consume at least 10 gm glucose as a snack or drink.
No two consecutive blood glucose estimations may be substituted by a snack.
The shift supervisor should be given evidence periodically that blood glucose is well controlled.

PRECAUTIONS:

If the blood glucose (BG) falls below 3.5 mmol/L, the individual shall stop work and take at least 10 gm of readily absorbable glucose. If at recheck within 30 min., the BG is <5.5 mmol/L then further glucose shall be taken until BG is 5.5 mmol/L or greater, at which time the individual may resume shift.

If BG is between 5.5 and 16.5 mmol/L no action is required.

If BG is between 16.5 and 22 mmol/L, take appropriate action to lower BG. (i.e. with insulin and/or exercise). Recheck BG in 30 minutes.

If BG > 22 mmol/L then individual shall stop work and take corrective action (insulin), and then recheck BG every 30 minutes until BG < 22 mmol/L before resuming work. They should seek advice from a physician.

If the controller experiences blurring of vision he/she should cease work and check BG.

There should also be a set of instructions for shift supervisors.

Appendix 3

SELECTION CONDITIONS FOR INSULIN TREATED DIABETES APPLICANTS (ITDM)

– Cat. 4 R.P.P. & Student Pilot (Aeroplane) ITDM applicants will be considered for medical certification provided the following conditions are met:

No recurring hypoglycemic episodes requiring the intervention of another party during the past 5 years.
1 year stable blood glucose control as measured by:
– glycated hemoglobin (A1 or A1c levels) (patient/upper level normal ratio < 2.0)
– 90% blood glucose values > 5.5 mmol/L.
Must demonstrate good diabetes education & understanding and have a positive attitude towards monitoring & self control.
No evidence of hypoglycemia unawareness.
Medical evaluation by a specialist in diabetes every 3 months, to include glycated hemoglobin (A1 or A1c levels) levels and a log of blood glucose levels.
The initial medical report should include specialist reports from:

*a) an ophthalmologist
*b) a cardiologist (to include a Treadmill Exercise Test – TXT)
*c) a neurologist
*d) a nephrologist

All of these reports should be negative in terms of significant complications of diabetes.

Submission of a routine civil aviation medical examination report including a resting ECG at no less than 12 monthly intervals.
A report from a vision care specialist every 2 years.
A report from a cardiologist (to include a TXT) every 2 years over the age of 40.

Note: All ITDM applicants who have achieved medical certification will be monitored by a single physician within the CAM organization in order to maintain consistency and an adequate data base.

* Reports a, b and c may be in the form of a comprehensive report from a specialist in internal medicine.

Appendix 4

SELECTED ITDM APPLICANTS WHO MEET CATEGORY 4 R.P.P., STUDENT PILOT & CATEGORY 1R AIRLINE TRANSPORT PILOT LICENCE (ATPL) (AEROPLANE) MEDICAL CERTIFICATION CONDITIONS

Blood Glucose Management Prior to and During Flight

1. Individuals with ITDM shall maintain the appropriate supplies for blood glucose management, which shall include:

(a) A reliable calibrated glucose meter with memory chip and appropriate blood sampling equipment.

(b) A supply of 10 gm. portions of readily absorbable carbohydrate, appropriate to the duration of flight.

2. Prior to flight blood glucose must be greater than 6.0 mmol/L. Blood glucoses must be monitored every 30 minutes during flight. If the blood glucose falls below 6.0 mmol/L then 10 gms. carbohydrate should be ingested.

3. If, for operational reasons, the in-flight 30 minute blood glucose measurement cannot be done, then 10 gms. carbohydrate must be ingested, however, this shall not be done on two consecutive 30 minute occasions without a blood glucose measurement.

4. The blood glucose should be measured 30 minutes prior to landing and if below 6.0 mmol/L then 10 gms. carbohydrate must be ingested.

5. If the blood glucose should exceed 15 mmol/L then the individual should land as soon as possible and take corrective therapeutic measures.

Asthma

Guidelines on the Aeromedical Assessment of Asthma

Preamble

Asthma is a disorder characterized by increased responsiveness of the small airways to various allergens and non-specific stimuli resulting in widespread airways inflammation and reflex narrowing of the airways. It has a wide clinical spectrum varying from a single short-lived episode, requiring little or no medication to that of a constant, disabling condition requiring a combination of therapeutic agents. It's course and severity can be quite predictable in most, albeit less predictable in some. Sudden incapacitation is not a rare phenomenon and may pose a threat to aviation safety.

Aeromedical Significance

Acute asthma attacks may cause partial (or complete) incapacitation in the cockpit (or air traffic control workplace).
Acute asthmatic attacks may be precipitated in flight by the inhalation of fumes such as might occur in engine or electrical fires or from other agents which could act as bronchial irritants.
In severe asthmatics, particularly after a recent attack , actual pulmonary function may be worse than that determined from simple clinical examination. Consequently, hypoxia, as measured by oximetry, may develop at lower altitudes than normal. A humid environment and high pollen counts that may be encountered during low altitude flight can exaggerate airway responsiveness and predispose to more severe asthma attacks. Air trapping in chronic asthma can present an increased risk of barotrauma in high altitude flight, particularly if sudden decompression should occur.

Protocol for the Assessment of Risk

The applicant who discloses a diagnosis of asthma should be assessed against the subjective and objective criteria outlined below, and, when necessary, such applicants should be referred to a respirologist or specialist in internal medicine with an interest in respiratory medicine, for a more precise determination of the diagnosis, severity, treatment, and prognosis.

Subjective Criteria

age of onset;
nature of symptoms, past and present;
present medication regime, any recent change, and reason for change;
duration of present therapy;
compliance with therapy;
side effects of therapy (if any);
active smoking history;
and reaction to passive smoke.

Critical Criteria

number of emergency room visits in the last five years;
number of hospitalizations in the preceding five years;
ataia in childhood;
use of steroids, oral or IV;
severity of exacerbations: ICU admission, intubation requirement;
and length of recovery following exacerbation.

Objective Criteria

evidence of bronchospasm, dyspnea, chest hyperinflation;
other ancillary features of asthma: nasal polyps, rhinitis, eczema pulmonary function tests.

The most sensitive tests are the FEV1 (Forced Expiratory Volume in one second ) and MMFR (Maximum Midexpiratory Flow Rate).
Results below predicted normal for age should be questioned.
Results below 70% predicted, indicates a more serious problem.
Response to ß-adrenergic challenge - better or equal to 12%, and more than a 200cc change in FEV1.

Note: The decision to refer to a specialist should be based on discussions with the RAMO/AMO. Decisions concerning the use of the methacholine challenge tests should be made by the attending specialist.

Table 1 - Levels of Asthma Severity Based on Treatment Needed to Obtain Control

Asthma Severity	Symptoms	Therapy Required
Very Mild	Well controlled	None, or inhaled SABA
Mild	Well controlled	Inhaled SABA + low dose ICS SABA + ICS +
Moderate	Well controlled	LABA or other Rx additions
Severe	May or may not be well controlled	As above + oral steroids

Medications Available for Asthma Treatment

Short acting ß2 agonists (SABA): (terbutaline, salbu-tamol, albuterol)

drugs of choice for relief of acute symptoms and for short-term duration.
used for prevention of exercise induced bronchospasm.
side effects may include tremor, nervousness and tachycardia.

Long acting ß2 agonists (LABA): (formoterol, salmeterol)

Add-on therapy to inhaled steroids (see Canadian Asthma Consensus Report).
Or can be used as a SABA (particularly formoterol) for PRN use.

Methylxanthines (aminahylline)

rarely used these days for asthma. If used, question its use.
have a narrow therapeutic range.
potential for severe side-effects including cardiac arrhythmias, tremor and may induce convulsive disorders. Leukotriene receptor antagonists (zafirlukast, montelukast)
anti-inflammatory agent as "add-on" to steroid therapy in asthma.
no side effects.
their role in asthma is limited and response rate not predictable (30% of patients will do well on
these agents).

Inhaled gluco-corticosteroids: (ICS) (fluticasone, budesonide, beclomethasone)

highly effective and predictable asthma stabilizers.
infrequent clinically important side-effects (most often taical).
used in all stages of asthma.
combination therapy with a LABA now available.

Table 2 - Measures of Asthma Severity

	Severity of Asthma
Event or Measurement	Mild	Moderate	Severe
FEV1, or PEF, % of predicted	>80%	60-80%	<60%
Need for inhaled SABA	Every 8 or more h	Every 4-8 h	Every 2-4 h
Probability of:
Previous near fatal episode	0	0	0+
Recent admission to hospital	0	0	0+
Night time symptoms	0 to +	+	+++
Limitation of daily activities	0 to +	++	+++
Note: FEV1 = forced expiratory volume in 1 second; PEF = peak expiratory flow

Figure 1 - Continuum of Asthma Management

Figure 1 - Continuum of Asthma Management

Severity of asthma is ideally assessed by medication required to maintain asthma control. Environmental control and education should be instituted for all asthma patients. Very mild asthma is treated with short-acting ß₂-agonists are needed more than 3 times/week (excluding 1 dose/day before exercise), then inhaled glucocorticosteroids should be added at the minimum daily dose required to control the asthma. If asthma is not adequately controlled by moderate doses (500-1000 µg/d of beclomethasone or equivalent), additional therapy (including long-acting ß2-agonists, leukotriene antagonists or, less often, other medications) should be considered. Severe asthma may require additional treatment with prednisone.

The above diagram is from the Canadian Asthma Consensus Report, 1999.

Recommendations

1. All Categories-Initial Applicants

When there is a significant history of asthma (emergency room visits within the past two years) or when medication usage to prevent/treat airways inflammation and bronchospasm is in excess of the "mild" criteria in the Tables above), the applicant should be referred to a specialist for clinical assessment including an objective appraisal of asthma through pulmonary function tests (usually spirometry, flow-volume loop, bronchial challenge and at times a study of residual volume, oximetry, etc).

2. Initial or Renewal Applicants

Very mild and mild asthma by clinical or 'challenge' * definition may be acceptable for Category 1, 2 , 3 or 4 if symptoms are well controlled by daily inhaled steroids or occasional aerosol bronchodilators.
Moderate asthma should be referred to the Aviation Medical Review Board (AMRB ) for a recommendation. All cases referred to the AMRB should have the appropriate specialist's report. A "restricted" category may be considered for renewal candidates only.
Severe asthma is disqualyifing for all categories of medical certification

* Methacholine challenge of 2.0 mg/ml or higher

3. Follow-up for all but "mild" applicants

An annual specialist report to include PFTs at the discretion of the specialist.

Note: Any increase in the severity of the asthma will necessitate reevaluation.

4. The use of SABA /LABA should be restricted to eight hours or more prior to flying, but may be used in an unusual asthmatic attack in flight to allow the safe completion of the flight.

References

Canadian Asthma Consensus Report, 1999.
Supplement to CMAJ 1999; 161 (11 Suppl)

Special Thanks to Drs Jocelyn Deneault and André Peloquin

Psychiatry (SSRIs)

Guidelines for the Non-Psychotic Psychiatric Conditions

BACKGROUND

The determination of “fitness to fly” is a complex process. It has been said that the license to fly is a privilege not a right and is governed by a set of rules and requirements. The rules are encompassed in the Canadian Aviation Regulations. The requirements include proof of age and citizenship; proof of having met the knowledge requirements; proof of having met the skill requirement; proof of having met the experience requirement; payment of the appropriate fees and proof of medical fitness.

The medical fitness aspect is outlined in CAR 424.17(4) and applied using polices, guidelines and acceptable practices, and in accordance with accredited medical opinion. Many factors are considered but paramount is the safety of the flying Canadian public, the public in general and the aviator him/her self. A risk assessment process is applied to every decision concerning medical fitness to fly. Factors, such as risk of sudden or subtle incapacitation or degradation of decision making, judgement, or information management, coupled with the operational aspects of the intended flight, exposure to other hazards or aircraft, to name a few, are factored in to the disposition equation.

Each disposition decision is unique in its own way and cannot be cited as the “rule” for the next case. Precedence is set with each case but cannot be used precisely to measure the merits of the next case.

As stated earlier, the Canadian Aviation Regulations Part IV, Standard 424.17 (4) specifies the physical and mental standards for medical categories. The standard related to mental issues is stated in 1.3 (a), 2.3(a), 3.3(a), 4.3(b):

“The applicant shall have no established medical history or clinical diagnosis which, according to accredited medical conclusion, would render the applicant unable to exercise safely the privileges of the permit, licence or rating applied for or held, as follows: (a) psychosis or established neurosis.”

At first glance this would render anyone with any history of depression, anxiety or other neurosis unfit to be licensed to fly. However, Transport Canada Civil Aviation Medicine has developed an approach to this issue that considers individual circumstances more intently.

Additionally, the use of medications for treatment of these disorders raises regulatory questions as stated in 1.1(d), 2.1(d), 3.1(d), 4.1(d):

“The applicant shall be free from (d) any effect or side effect of any prescribed or non-prescribed therapeutic medication taken, such as would entail a degree of functional incapacity which accredited medical conclusion indicates would interfere with the safe operation of an aircraft during the period of validity of the licence.

Again, recognizing that the use of medications to treat mental issues is generally a positive step, but does complicate the considerations for medical certification TC CAM has established an approach that individualizes the decision making process.

The development of this protocol arose from the recognition that the prevalence of depression in aircrew is estimated to be about 6%, similar to the general population. Cross-sectional surveys have shown the anxiety disorders to be even more prevalent in the general population, even though depression is seen more frequently in clinical settings. Unfortunately, the number of pilots coming to the attention of aviation medicine authorities does not reflect the prevalence data. This could be a reflection of several factors. Transport Canada policies related to this issue have traditionally required immediate medical suspension, often for extended periods or permanently and limited the opportunities and options for return to flying duties. The argument has been made that this approach inevitably leads many aviators to forego treatment and suffer in silence. Alternatively, they seek medical care without revealing to the treating physician that they are an aviator in order to avoid a report to aeromedical authorities. Some others use herbal remedies and antidepressant medications, acquired via the Internet or other sources, without proper psychiatric or aeromedical supervision. Such avoidance behaviours are often aided and abetted by physicians who are unaware of their responsibility under The Aeronautics Act to report to Transport Canada any medical condition or treatment that might have implications for flight safety.

The clash between inflexible medical regulation and advances in medical therapies, coupled with the dilemma of no treatment or non-disclosed on the pilot side have led TC CAM to develop risk management strategies to preserve aviation safety and pilot resources.

The wide spread use of medications for these disorders in the general public and even in other safety sensitive occupations has raised the question about their use in the aviation community. To that end Transport Canada has embarked on a carefully controlled approach to allowing the use of medications for certain medical conditions in carefully selected circumstances. The watchword is individual consideration not blanket authorization or acceptance. The evidence upon which to base a permanent solution has not been gathered fully in the aviation environment. Some countries have taken the initial steps to test the hypotheses and have not seen any signs that the industry or the public has been affected adversely by the decision to allow stable depressed aviators to continue to fly while taking medications.

The use of medications has always been a concern for aviation. There have been many advances over the years in a number of specialty areas where previously medication use was extremely limited (hypertension), and where simple combinations were once forbidden. Now, combination therapy with complex medications is the norm.

In the realm of treatments for psychiatric disorders, there have been many changes. The risk to aviation safety from an untreated aviator or one not disclosing treatment must be weighed against the acceptable use of newer psychotropic medications with well-established records of efficacy and minimal side effect profiles in a well-monitored situation.

Previous antidepressant medications generally had side effects quite incompatible with flying duties, including fatigue, drowsiness, and marked anticholinergic effects. In the past decade, increasing experience has been gained with the new generation of antidepressants (SSRIs and SNRIs) whose effect is to modulate the intracellular action of various brain neurotransmitters, whose imbalance is thought to be a causative factor in anxiety and depression.

There is an increasing consensus of medical opinion that it is possible to allow the use of these medications in aircrew, in circumstances that would not compromise flight safety or operational effectiveness, and, on the positive side, would allow the preservation of trained aircrew resources. On the negative side, there is widespread recognition that medical personnel sometimes collude with patients and choose diagnoses or treatments to avoid raising regulatory barriers to flying. This has lead to inappropriate diagnosis (e.g., diagnosing adjustment disorder when depression is more appropriate) to avoid grounding, or using bupropion under the pretext of smoking cessation in order to treat depression. Efforts to avoid prolonged grounding may also contribute to undertreatment, avoiding the use of medications and thereby adding to morbidity, which may paradoxically extend the time required before return to aviation duties is possible. There is often considerable overlap between the clinical syndromes of depression and anxiety, leading to co-morbid diagnoses and similar treatments, with SSRIs, currently the mainstay of treatment for both.

Virtually all of the medications used to treat this class of psychiatric disorder have similar efficacy. They also have similar side effect profiles, including potential discontinuation symptoms, but may vary somewhat in the relative frequency and severity of these side effects. Adverse effects tend to occur early in treatment and diminish as the patient becomes physiologically accustomed to the medication. This individual variability obviates the need to specify a preference for approval of one medication over another, especially since personnel will be required to be demonstrably free of symptoms or neurocognitive side effects no matter what the medication. The most common side effect with prolonged treatment is sexual dysfunction, which may not be aeromedically significant but may lead to cessation or alteration of therapy.

AEROMEDICAL CONCERNS

This Guideline applies to all aviation personnel and applicants with a recent history (within the past two years) or current use of any Selected Serotonin Reuptake Inhibitor (SSRI), or diagnosis of mood disorder for which treatment included medication.

(Closely related medications, such as Selected Norepinephrine Reuptake Inhibitors (SNRIs) and Selective Monoamine Reuptake Inhibitors (SMRI) with similar efficacy and minimal side effect profiles (e.g., bupropion, venlafaxine) will also be considered)

This Guideline applies to psychiatric disorders such as, but not limited to:

Major Depressive Disorder,
Dysthymia,
Depressive Disorder NOS,
Medication use in support of Adjustment Disorder with affected mood,
Posttraumatic Stress Disorder,
Acute Stress Disorder,
Generalized Anxiety Disorder,
Anxiety Disorder NOS.
Premenstrual Dysphoric Disorder (PMDD) treated with a SSRI.

Consideration may be given to other situations where these medications have been prescribed, such as for eating disorders, obsessive-compulsive traits, and social phobias, etc.

Those persons who have had a previous history of minor (non-psychotic) mental problems requiring medications and who have now ceased the medication may be considered after an appropriate period off medication and demonstrated continuing stability.

To be considered for this protocol, one’s treatment must generally be limited to a single agent in a class that has been approved by Health Canada for treatment of the listed disorders above. An exception to monotherapy may be the addition of appropriate medication to a therapeutic dose of an SSRI for the management of medication-related sexual dysfunction.

The process for approval to fly or return to flying may be a lengthy one and will often take more than 6 months, due to the requirement for being on maintenance therapy for at least 4 months prior to submission of a request for acceptance.

Protocol to gain consideration for exception to Standards

Initial Applicants

For the initial applicant who has a recent past history of problems covered in this protocol, the issue comes down to assessing the severity and precipitants of the event, the confirmation of the recovery from the event and the potential for reoccurrence during the validity period of the desired license or permit.

This is especially important for an applicant who wishes a Category 1 medical certificate – his person will be in a position where the safety of the fare paying public is front and center and expectations about the pilot’s medical competency and stability are high. While not a pure medical factor, the potential for future interruptions in the pilot’s career path and disruptions to his future employer cannot be dismissed entirely. Training costs are high and potential problems that can be predicted cannot be ignored, both for person and the system.

Category 3 aviators, on the other hand, can be given some leeway because of their relative low flying times, smaller aircraft, less interaction in high traffic areas and more choice about when to fly, for example.

Category 1
Medical Certification will be considered on a case-by-case basis after review of the required elements outline below. Medical Certification may be granted where the underlying disorder is of a discrete nature with a favourable prospect of low recurrence in the future.

Follow-up requirements for acceptable applicants are outlined below.

Category 2 – Air Traffic Controller
Medical Certification will be considered on a case-by-case basis after review of the required elements outlined below.

Follow-up requirements for acceptable applicants are outlined below.

Category 3
Medical Certification will be considered on a case-by-case basis after review of the required elements outlined below.

Follow-up requirements for acceptable applicants are outlined below.

Category 4
Medical Certification will be considered on a case-by-case basis after review of the required elements outlined. A Medical Declaration is not acceptable for application.

Follow-up requirements for acceptable applicants are outlined below.

Experienced aviation persons

All Categories
Previously qualified aviation personnel who experience medical issues covered by this guideline will be considered on a case-by-case basis after review of the required elements outlined below.

Follow-up requirements for continuing medical certification are outlined below.

Elements required for consideration

Initial applicants:

Those applicants with a history of conditions covered by this protocol will need to submit a detailed report from the attending physician. This can be a family physician but may include a psychiatrist or psychologist if deemed necessary after initial assessment of the report by Civil Aviation Medicine medical staff or CAM’s specialist consultants.

The report from the psychiatrist or prescribing physician (non-psychiatrist) must include, as a minimum, the history of symptoms, specific diagnostic conclusions supporting one of the included diagnoses listed above, medication history and effectiveness, side effect profile and current status, narrative summary or treatment records documenting an uncomplicated illness without evidence of psychosis or suicidal behaviour.
Those initial applicants who are still on medications must be at a stable dose for at least 4 months without aeromedically significant symptoms/side effects before submitting a detailed report from their attending physician. This can be a family physician but may include a psychiatrist or psychologist if deemed necessary after initial assessment of the report by Civil Aviation Medicine medical staff or their specialist consultants.

The report from the psychiatrist or prescribing physician (non-psychiatrist) must include, as a minimum, the history of symptoms, specific diagnostic conclusions supporting one of the included diagnoses listed above, medication history and effectiveness, side effect profile and current status, narrative summary or treatment records documenting an uncomplicated illness without evidence of psychosis or suicidal behaviour.

In selected cases, specifically for Category 1 and 2, a neuropsychological assessment may be required. That report shall include cognitive domains and motor skills testing (e.g., CogScreen) to demonstrate functional ability.

Licensees with change in medical status

Licensees who experience a change in medical status covered by this protocol will usually come to attention through several mechanisms, including self-reporting, consultation with their Civil Aviation Medical Examiner, or from the attending physician in accordance with the Aeronautics Act.

As an initial step, their Medical Certificate will be formally suspended pending assessment of their condition.

Subsequently, a more detailed report from the attending physician will be requested by CAM. A psychiatrist or psychologist report may be requested after initial assessment of the report by Civil Aviation Medicine medical staff or their specialist consultants.

The report from the psychiatrist or prescribing physician (non-psychiatrist) must include, as a minimum, the history of symptoms, specific diagnostic conclusions supporting one of the included diagnoses listed above, medication history and effectiveness, side effect profile, current status, and narrative summary or treatment records, documenting an uncomplicated illness without evidence of psychosis or suicidal behaviour.

In selected cases, specifically for Category 1 and 2, a neuropsychological assessment may be required. The report shall include cognitive domains and motor skills testing (e.g., CogScreen) to demonstrate functional ability.

For those situations where the condition is short-lived (less than 4 months) and the medication is stopped and there is stability demonstrated by a report from the attending physician or specialist, consideration for reinstatement may occur in short order.

For those situations where stability is reached but continuing medication is recommended, consideration may be undertaken after 4 months of stable medication, dosage and type, and report of no side effects.

FOLLOW-UP REQUIREMENTS

Applicants and licensees who have been assessed and deemed suitable for medical certification will be expected to comply with the following ongoing requirements or be subject to suspension of the medical certificate.

The Category 1 aviator who is stable on medication will be required to undergo evaluation by a psychiatrist every 6 months for the duration of treatment, plus six months after medication cessation to insure stability.

The results from a simulator ride or an operational assessment may also be requested to support the case.

The Category 2 air traffic controller who is stable on medication will be required to undergo evaluation by a psychiatrist every 6 months for the duration of treatment, plus six months after medication cessation to insure stability.

The results from an operational assessment may also be requested to support the case.

The Category 3 or 4 aviator is stable on medication will be required to submit a report from their attending physician quarterly for the duration of treatment, plus three months after medication cessation to insure stability. In some circumstances, a report from a psychiatrist may be required.

In all Categories, any relapse, change in mental health, or return to medication after cessation is disqualifying and will require a suspension of the medical certificate and complete assessment as outlined previously.

In all Categories, changing dosage or discontinuation of medication requires temporary grounding, a report from the attending physician or specialist and close monitoring for aeromedically side effects or onset of significant symptom, and reassessment of certification status.

Other Policies

Ear, Nose and Throat

Hearing:

Audiogram if doubt raised by screening examination. Acceptable limits:

35 db at 500 Hz
1000 Hz
2000 Hz
50 db at 3000 Hz

If hearing doesn't meet standard on audiogram the applicant will likely need Practical Hearing Test.
Drum Perforation:

A single dry perforation is acceptable. An acute perforation will result in being unfit until hearing and the tympanic membrane recovers.
Otitis media:

Unfit until recovered
Sinusitis:

Unfit until recovered.
Menière's Disease:

Disqualifying. ENT consult will be needed to confirm diagnosis.
Labyrinthitis:

Unfit while acute. ENT consult will be needed in non-infective vestibular disorders.

Ophthalmology

Myopia:

Initial medical Category 1,2 or 3 - need glasses prescription if uncorrected visual acuity is 6/60 (20/200) or worse.
Cataracts:

Unfit when vision in affected eye no longer meets standard.
Intraocular Lenses:

Unfit for 6 weeks following surgery. Full report from attending ophthalmologist.
Colour Vision Deficiency:

If applicant fails pseudoisochromatic plate test, he will be given restricted medical certificate (Daylight only, 2 way radio required at controlled airports). Those who fail plate test may try a colour lantern test or Farnsworth D-15.
Contact Lenses:

Can be approved for all categories:
Refractive Surgery:

(See guidelines on Page OP-3)

Respiratory

Pneumonia:

Unfit until fully recovered.
COPD/Emphysema:

Usually disqualifying if it requires active treatment. Pulmonary function tests and arterial blood gases or oxymetry usually required. Consultation with a respirologist or internist is usually required.
Asthma:

(See guidelines on Page A-1.)

Gastrointestinal Disease

Acid Peptic Disease:

Dyspepsia or esophagitis treated with antacids alone is acceptable. Long term maintenance with H2 antagonists is acceptable if there are no significant side - effects.
Gastric/Duodenal Ulcer:

Disqualifying while ulcer is present and under active treatment. Long term maintenance with H2 antagonists is acceptable if no significant side - effects.
Hernia:

Significant hernias are disqualifying until the hernia is repaired. If there is any question about the significance of a hernia a surgical consultation is required.
Cholelithiasis/Cholecystitis:

Cholecystitis is disqualifying. Presence of stones with a history of symptoms is disqualifying. Asymptomatic cholelithiasis as an incidental finding may be acceptable.

Genitourinary Disease

Renal Calculi:

Single episodes my be acceptable after recovery if IVP or ultrasound shows no stones present, and a metabolic work-up is normal. Repeated episodes will need a full work-up and individual assessment.
Cancer of the Prostate:

May be acceptable after treatment. Will need full report from urologist or oncologist. Follow-up reports including PSA will likely be required.

Metabolic Disease

Diabetes Mellitus: (See Section D1 -D10.)
Thyroid Disorders:

Hypothyroidism is acceptable if adequately treated and stabilized. Hyperthyroidism requires full report from internist or endocrinologist and treatment stabilization prior to assessment.

Musculoskeletal Disease

Locomotor Dysfunction:

Includes all amputations, malformation, arthritis and loss of function. All will be assessed on an individual basis. Full description is required. Practical Flight Test may be required.

Psychiatric Disease

Anxiety Disorder:

Disqualifying if requiring active treatment with tranquilizers. Will likely require a psychiatric consultation.
Depression:

Ongoing depression is disqualifying condition. May be recertified after full recovery and cessation of treatment. Waiting period prior to recertification will be individually assessed. Report from attending physician or psychiatrist likely required.

Note: Applicants who have been treated for a depressive illness and who are on maintenance or prophylactic therapy with non-sedating selective serotonin reuptake inhibitors (SSRIs) may be considered for medical certification on an individual basis after review by the CAM Aviation Medicine Review Board.
Substance Abuse/Dependence:

Disqualifying. Once "recovering", an individual assessment to assess risk of relapse. Restricted category may be recommended. Continued abstinence is the key to medical recertification.

Malignancy

Malignancy:

Each case assessed individually. Active chemotherapy is disqualifying. Will need: pathology report and report from oncologist to include staging, treatment, prognosis and follow - up plans.

HIV/AIDS

Applicants who are HIV seropositive may be considered for medical certification on an individual basis. The major concern is the development of HIV related psychiatric or neurological complications. CD-4 cell counts and "viral load" measurements will be taken into account. For further information contact your RAMO.

Requirements for Medical Certification Following Refractive Surgery

Refractive Eye Surgery

One of the areas where Civil Aviation receives a lot of questions is the visual requirement to be a pilot. Contrary to popular myth, perfect uncorrected vision is not a requirement to be a pilot or an air traffic controller. Glasses, contact lenses and refractive surgery are all (with certain limitations) acceptable ways to correct visual acuity problems.

Technological changes and medical experience has brought forward a proliferation in the availability and options in eye surgery directed at improving visual acuity. Civil Aviation Medicine has monitored the progress and has adapted the medical guidelines regarding certification for flight to reflect the growing body of knowledge and experience in this important area.

Which Procedure does Transport Canada (TC) recommend?

TC's position in this regard is that refractive surgery is an elective procedure, i.e. a voluntary personal decision entered in to after careful consideration of the risks and benefits and discussions between the pilot and his/her attending physicians.

While there are many techniques available, some earlier methods are dropping out of favour while others are evolving rapidly both in technical precision and popularity. The list includes clear lens extraction, Radial Keratotomy (RK), Astigmatic Keratotomy (AK), Automated Lamellar Keratoplasty (ALK), Photorefractive Keratectomy (PRK), Laser-assisted in-situ Keratomileusis (LASIK), Laser Thermokeratoplasty (LTK) and Intrastromal Corneal Rings (ICR), to name only a few. The details of these procedures are beyond the scope of this document; further information is available from the Ophthalmology community.

Which Surgical Centre does TC recommend?

TC’s Medical Advisors cannot direct prospective candidates to a specific service provider. There are many providers available, using a variety of techniques and having a wide range of experience and success. Anyone considering a procedure should spend some time investigating the procedure and the provider. The watchword should be “Caveat emptor” - BUYER BEWARE.

Why does TC have concerns about this procedure?

While the advances in this area of surgery have been impressive and the outcomes have improved in terms of fewer complications and shorter period of incapacitation, there are still issues that have a serious potential for affecting safety in flight. The most important risks from an aviation standpoint are loss of best corrected visual acuity, undercorrection, or overcorrection, fluctuation in vision at different times of the day, glare, “halo” or “starburst” effect due to corneal haze, loss of contrast sensitivity, loss of low contrast visual acuity and regression or return towards pre-operative refractive levels.

It is, therefore, quite important that these concerns are adequately addressed in the post-operative period before a return to active operational flying or air traffic controller duties is permitted.

Who needs to know when this surgery has been done?

You need to inform the eye centre that you are a pilot/air traffic controller. They have an obligation to report your situation to TC Civil Aviation Medicine. You should inform your Civil Aviation Medical Examiner (CAME), as s/he needs to up-date your file and ensure that you are aware of your obligations with respect to grounding yourself. While there is no requirement to inform the Regional CAM office directly, you might want to consider it if you are in a career situation where return to authorized flying activities is a priority. This would alert CAM and help to expedite the re-certification when the reports are ready.

Failure to inform TC/CAM about this surgical procedure could lead to Enforcement action should the circumstances come to light in the future. “Miraculous” improvements in visual acuity found at renewal medical examinations with your CAME will be pursued.

Non-disclosure to aviation employers will undoubtedly result in a similar dim view of the situation. The majority of carriers/employers will accept these procedures if Transport Canada has approved the medical certificate. For those persons thinking about a flying career in the Canadian Forces, it would be prudent to check on the military’s current medical policy for aircrew entry and activity.

What documents do I need to submit in order to reinstate my license after undergoing this procedure?

Submit a report at 30 days (4 weeks) post-surgery to the local office of your Regional Aviation Medical Officer (RAMO), using the Refractive Surgery form (to complete the PDF form, you will need to download it to your computer) found on the TC CAM website.

Refractive Surgery For Visual Acuity Correction

If ophthalmic medications (eye drops or oral) are still being used to control pain or other symptoms, then the report should be delayed until medications have ceased. This does not apply to the so-called “artificial tears”.

The report can be from the attending ophthalmologist or an optometrist and should include information concerning;

the pre-operative visual acuity,
the date of the surgery,
the type of procedure,
the size of the ablation zone (area of surgery),
the post-surgery visual acuity and,
any comments concerning side-effects, such as haze, glare night vision problems, or contrast sensitivity issues.

Will I need any other reports?

TC/CAM is currently requesting a follow-up report if there are any post-operative complications that arise beyond the initial assessment period. You can use the same form as the original reports. An ophthalmologist or an optometrist can complete this report.

What about “touch-ups”?

Generally speaking, a “touch –up” is a repeat procedure to improve upon the original surgery. In these cases we would need another report at 30 days (4 weeks) post the touch up procedure to confirm the visual acuity and lack of side effects.

How long does one have to wait before returning to flying or Air Traffic Controller activities?

Return to flying must be delayed until TC/CAM has reviewed the results of the surgery. A follow-up report should be submitted 30 days after the procedure. You can fax or mail the report to the local RAMO and you should receive prompt notification that you can return to flying if all is satisfactory.

What about the restrictions printed on my current Medical Certificate referring to glasses or contact lenses?

Refractive surgery usually results in a change in visual acuity that permits flying without corrective lenses. If this is the case, your file will be re-assessed and you will be issued a new Medical Certificate or a “sticker” (new licensing booklet) that reflects the change.

Photorefractive Keratectomy (PRK) and Laser Assisted in Situ Keratomeulesis (LASIK)

Patient's Name: _________________________
File No. __________________________________
Date of Surgery: _____________________________
Surgical Technique: ___________________________
Number of treatments: ________________________
Size(s) of Ablation Zone(s): _____________________

Uncorrected Acuity

Pre-operative data:
OD __________
OS __________

3 Months Post PRK:
(may be completed by
an Optometrist)
OD __________
OS __________

6 Months Post PRK:
(may be completed by
an Optometrist)
OD __________
OS __________

Refraction & Corrected Acuity

__________ = _________
__________ = _________

__________ = _________
__________ = _________

__________ = _________
__________ = _________

Are there any of the following:

Glare sensitivity or "haloing"

Yes _____ No _____

Night vision difficulty

Yes _____ No _____

Diurnal variation of vision

Yes _____ No _____

Use of ocular medication

Yes _____ No _____

Corneal haze

Yes _____ No _____

Loss of contrast sensitivity
/acuity (this has potentially
serious implications in the aviation environment)

Yes _____ No _____

Signature of attending Ophthalmologist/ Optometrist _________
Date: ___________ Phone: ( ) __________

May 1999

Aeronautics Act (1985) Medical and Optometric Information

Minister to be provided with information

6.5 (1) Where a physician or an optometrist believes on reasonable grounds that a patient is a flight crew member, an air traffic controller or other holder of a Canadian aviation document that imposes standards of medical or optometric fitness, the physician or optometrist shall, if in his opinion the patient has a medical or optometric condition that is likely to constitute a hazard to aviation safety, inform a medical adviser designated by the Minister forthwith of that opinion and the reasons therefore.

Patient to advise

(2) The holder of a Canadian aviation document that imposes standards of medical or optometric fitness shall, prior to any medical or optometric examination of his person by a physician or optometrist, advise the physician or optometrist that he is the holder of such a document.

Use by Minister

(3) The Minister may make such use of any information provided pursuant to subsection

(1) as the Minister considers necessary in the interests of aviation safety.

No proceedings shall lie

(4) No legal, disciplinary or other proceedings lie against a physician or optometrist for anything done by him in good faith in compliance with this section.

Information privileged

(5) Notwithstanding subsection (3), information provided pursuant to subsection (1) is privileged and no person shall be required to disclose it or give evidence relating to it in any legal, disciplinary or other proceedings and the information so provided shall not be used in any such proceedings.

Deemed consent

(6) The holder of a Canadian aviation document that imposes standards of medical or optometric fitness shall be deemed, for the purposes of this section, to have consented to the giving of information to a medical adviser designated by the Minister under subsection (1) in the circumstances referred to in that subsection.

Contacts

Civil Aviation Medicine contacts and offices

Handbook for Civil Aviation Medical Examiners - TP 13312

Table of Contents

Foreword

Civil Aviation Medical Standards

Section 1

CAM Headquarters

Regional Offices

Licensing

Civil Aviation Medical Examiners (CAMEs)

Termination of Appointments

The Medical Examination

Figure 2 - Medical Examination Requirement Chart

Completing The Medical Examination Report

Part A

Part B

Part D

Part C

General Physical Examination

Height and Weight

Blood Pressure

Identifying Marks

Nutrition

Nose and Throat

Ear Drums

Respiratory System

Cardiovascular

Abdomen Including Hernia

Genitourinary

Locomotor

Neurological

Mental Status

Integument

Part C - Visual Examination

Part C - Hearing Examination

Part C - Renewing a Medical Certificate

Civil Aviation Medical Examination Report Form

Completing the Medical Examination Report Form

Part A

Part B

Part D

Part C

Appendix 1

The Maddox Rod Test

Definitions

Appendix 2

Colour Vision

Section 2

The Atmosphere

Composition

Divisions

Ozone

Atmospheric Pressure

Cosmic Radiation

Hypoxia and Hyperventilation

Respiratory Physiology

Hemoglobin Dissociation

Hypoxia

Hyperventilation

Pressurization and Depressurization

For Those of Mathematical Bent

Dysbarisms and Altitude Sickness

Barotitis

Other Barotraumas

Intestinal Gas

Inflatable Medical Aids

Decompression Sickness

Bubble Formation

Symptoms

Neurological Effects

Provocative Factors

Scuba Diving

Acceleration

G Axes

Physiological Effects

Positive Gz

Negative Gz and Jolt

Transverse and Lateral G

Orientation and Disorientation

Vision

The Vestibular System