Chapter 1 : The Problem

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Currently within Canada, there are hundreds of thousands of persons being transported for business or pleasure over inland waterways, lakes and rivers. Moreover, there are thousands of Canadians who earn their living working on or flying over water. Depending on the local climate, transportation may occur throughout the year or be limited to when the passage is ice free. Irrespective, for a large portion of the year, particularly the winter, spring, and early summer, the water is cold.

Recently, (June 2000), there was an accident in Georgian Bay where two children drowned after the True North ll sank within two minutes (Reference 162). The question has been asked as to what steps should be taken to prevent this from re-occurring. Carriage of lifejackets is already mandatory. Should there be any change in the regulations? Carriage of liferafts or immersion suits within Canada’s internal waterways is not mandatory when operating close to shore. Should a change of policy be made on this requirement? If there are to be any changes in policy on the wearing of immersion suits, lifejackets or carriage of liferafts, should it be related to the physical water temperature at the time the vessel is operating? Finally, are Canadian national immersion suit standards adequate and how do they relate to the lifejacket standards and how do they interrelate to international standards? These questions will be addressed in the following chapters with conclusions and recommendations.

Drowning in Cold Water: How and Why Does it Happen?

Records of death from immersion in cold water date back to ancient times. Circa 450 BC, Herodotus (Reference 77) wrote of the sea borne expedition against Athens by the Persian general Mardonius. He clearly distinguished drowning from hypothermia, when he wrote, "Those who could not swim perished from that cause, others from cold" (Reference 56). In spite of hundreds of thousands of maritime disasters, the precise medical cause of death has been rarely noted. Death has commonly been ascribed to "drowning" or being "overcome by the sea". In the 18th and 19th century, James Lind (1762) mentioned the dangers of collapse after rescue (Reference 102), and James Currie (1797) observed deterioration of his subjects before improvement (Reference 41).

Loss of life at sea was accepted as an occupational hazard and fate. Wrecking was not made illegal until 1807 and the Royal Navy’s use of impressment was not abandoned until 1815. Thus, such items as lifejackets, which could be used to aid escape were not encouraged. Shipwrecked sailors had to cling to wooden spars, and water and rum barrels (Reference 29). Since very early times, the Eskimos understood the dangers of sudden cold water immersion. They used suits called "spring-pels", these consisted of sealskin or seal gut stitched together to form a complete waterproof covering when sailing in their kayaks (Vanggaard, 1988) (Reference 168). A version of this suit is in the Danish National Museum (Willett, 1988), (Reference 172) (Bricket-Smith, 1924), (Reference 26). However, this concept was not adopted by professional mariners and fishermen.

Little specific design of immersion suits was conducted until the middle of the 19th Century. The only work on survival equipment had been the pioneering work of Captain John Ross Ward in the development of a life jacket in 1851 for the National Lifeboat Institution (Reference 99). In 1869, Captain Stoner invented a patent life saving apparatus, which was revolutionary for the time and addressed all the fundamental modern day requirements of a survival suit. It included a waterproof suit, a lifejacket, head protection, a signalling device and paddles for aiding passage through the water (Figure 1) (Reference 44).

Figure 1: Captain Stoner’s Patent Life Saving Apparatus

 

Lee (1960) reported that: "An exposure suit was brought from America by Merriman in about 1870. It consisted of a complete waterproof dress with the upper part inflated with air, and it protected the body from loss of heat; the face was the only part of the body exposed. When inflated it had a buoyancy of 30 lbs¹. The Board of Trade bought a number of them in 1872 and supplied one to each of their Lifeboat Stations." (Reference 96). With the advent of iron ships around 1850, not only did the ships sink faster, but also there was less flotsam for flotation. Consequently, there was an increase in the loss of life at sea. In 1871, it was reported that 2740 British seamen lost their lives through drowning (Reference 29).

Aury (1955) reported that: "In 1875, Captain Boyton, wearing an inflatable swimsuit, attempted to cross the English Channel, propelling himself by paddles and a small sail. He had to give up after sixteen hours in the water. In a second attempt two months later, he carried provisions, rockets and a trumpet and successfully crossed from Cape Gris Nez to Dover in 24 hours" (Reference 12).

No one paid attention to the observations by Lawrence Beesley (1912) (Reference 20). He was a survivor from the Titanic who noted that the victims wearing lifebelts and in cold, but calm water had died of cold. The official cause of death was given as drowning. Although the International Safety of Life at Sea ( SOLAS ) Committee was formed directly as a result of this accident, no thought was given to personal protection. Everyone was obsessed with floating in and not on the water. In 1912, Mr Boddy demonstrated his "Boddy" Life Saving jacket in the English Channel off Cowes, but his efforts came to nought even though it was approved by the Board of Trade for aviation (Reference 1).

Following the Empress of Ireland accident in 1914, a Mr Macdonald of Portland, Oregon demonstrated his waterproof rubber survival suit and lifejacket in the harbour in Montreal, but no one paid much attention to it (Reference 29). 12,000 British merchant seamen and 5354 German naval officers and men drowned during World War l, yet again, no one asked why (Gilbert, 1994) (Reference 50). Toward the end of that war, Walter Fry developed a lifesaving suit, which was tested by the US Navy in January 1918 at the Brooklyn Navy Yard, but nothing seems to have come out of that either (Hiscock, 1980) (Reference 79). Ultimately, the US Navy and Coastguard developed a combination flotation and exposure garment for aviators. The "Dreadnaught Safety Suit" made of rubberized material and padded with kapok was reported to be in use at the Naval Air Station Pensacola in the winter of 1918 – 1919 (Reference 29).

After World War I, the British Merchant Advisory Committee met in 1922 to review lifesaving appliances (Reference 112). Their review of passenger ships lost between 1914 and 1922 revealed that, 10,024 (21%) of crew and passengers had lost their lives. The whole report concentrated on the multiple failures that occurred in the mechanics of launching lifeboats into the water. One very small section was devoted to a simple applied cold water physiology experiment conducted by Hill on the effect of clothing on the laboratory assistant Mr. Pergarde, protected by a Macintosh coat or sack, and oil skin coat and waders. He was exposed to water temperatures down to 16° C . The significant conclusion was:

Yet, no one acted on this profound and correct statement, nor did any recommendations pertaining to this discovery appear in the extensive report; it was hidden away in one of the Annexes!

In 1928, the Vestris foundered off Chesapeake Bay and 112 passengers and crew perished. The SOLAS committee was recalled, but no advice was given to do research on personal protection. The only positive step taken in 1928 was the use of a tailor’s dummy or manikin to investigate the performance of the lifejacket and protective oilskins in turbulent seas. This had been precipitated by the loss of all 17 crew of the Rye Harbour lifeboat in the English Channel (Reference 100). The policy, right up the Second World War and the following ten years was still to rely on flotation in rather than on the water using lifeboats, Carley floats and a series of Balsa, Spanner or Denton rafts.

It was the inadequacies of life saving equipment during the Battle of the Atlantic in the Second World War that was the catalyst for scientific examination of the problem. The progress of the design and development of immersion suits will be discussed in Chapter 2.

As Golden (1996) (Reference 57) clearly pointed out, official inquiries in an endeavour to prevent a recurrence, have been more interested in the cause of disaster than the cause of death of the crew and passengers. This is still the case as we enter into the 21st century. The recent issue of the Marine Investigation Report by the Transportation Safety Board of Canada on the sinking of the "True North ll" in Georgian Bay June 2000 extends to 63 pages (Reference 162). There are only five sentences assigned to the fact that two grade seven students died. One of the sentences curtly states: "The bodies were subsequently examined by the coroner who determined that the cause of death was drowning." There has been no thought put into why they drowned or even if they could swim in the first place. Thus, both funding and direction for physiology and human factors research has sadly lagged behind the technological advances in ship design.

The Knowledge: Physiology of the Immersion Incident to 1995

The Medical Research Committee (Reference 110) published a pamphlet in 1943 on "The Guide to the Preservation of Life at Sea After Shipwreck". This was based on the observations of naval medical officers who had treated survivors, and on 279 survivor interviews. This was the basis from which all the modern physiological research has been conducted.Two other reports were to follow after the War that revealed the shocking loss of life at sea which could have been prevented. The first was the Talbot Report (Reference 147) published in 1946.This showed the inadequacy of the RN lifebelt and the Carley type floats. Over 30,000 men died after escaping from their ships, in other words, during the survival phase. The second was the Medical Research Committee report by McCance et al (1956) which investigated "The Hazards to Men in Ships Lost at Sea 1940 – 1944" and examined the cause of death at sea in greater detail (Reference 108).

The pioneering work post-war was conducted under the auspices of the Royal Navy Personnel Research Committee and subsequently the Royal Navy Institute of Naval Medicine. This was basically summarized in Professor Keatinge’s monograph (1969) (Reference 92). As a result of all the aforementioned information, it had become clear that the human body cannot maintain its internal temperature when immersed in water below 25° C when conscious and shivering. The body temperature must progressively fall until death occurs. However, there was much more to the problem than this.

Golden and Hervey (1981) (Reference 56) identified four distinct stages in which a human immersed in cold water may become incapacitated and die. However, what is most important to note is that stages 1, 2 and 4 were largely regarded as of academic interest only; so they did not have a large effect on survival policy, international regulations and survival equipment. All of the effort was concentrated on stage three, that of hypothermia, on predicting the onset and prevention of hypothermia. Thus, there is still no consideration given to the physiological impact resulting from the first two stages of immersion in the design of emergency equipment. For instance, flares are still vacuum packed in polythene bags and as in the Estonia accident were not usable simply because no one had the grip strength or the tactility to open the bags. The bailer in the Estonia liferaft was wrapped in polythene and after attempting to open it with his teeth, one survivor finally gave up after he had lost several teeth!! (Reference 43) Anyone who works, flies or plays over cold water, those who design equipment for emergency use, and coroners and pathologists who investigate deaths in marine accidents must know about these four stages.

Stage 1. Initial immersion responses or cold shock

On initial immersion, there is a large inspiratory gasp followed by a four-fold increase in pulmonary ventilation, i.e. severe hyperventilation. This on its own can cause small muscle spasms and drowning. Along with this, there is a massive increase in heart rate and blood pressure. These latter cardiac responses may cause death, particularly in older, less healthy people. These effects last for the first two to three minutes, just at the critical stage of ship abandonment (Tipton, 1989) (Reference 153), (Tipton et al., 1994) (Reference 157).

Death from cold shock is not uncommon. These are typical examples that continue to be regularly reported in the Canadian press each year and demonstrate the practical evidence that cold shock kills.

Stage 2. Short-term immersion or swimming failure

Death at this stage, between three and thirty minutes after immersion, appears to affect those who try to swim. It has now become apparent that much more emphasis must be put on swimming failure as a cause of death. It must also be understood that ability to swim in warm water is no indication of how well a human can swim in cold water. The classic testimony heard in the coroner’s court is: "We saw him go over the side, he started to swim and by the time we had the boat turned around and tried to identify where he was lost, he had disappeared. How could that be? He was an excellent swimmer."

The cause was thought to be due to the respiratory and cardiovascular responses already started in the initial immersion. An alternative theory was that the cold water contact with the nose and mouth induced the "diving response". This causes breathing to stop (apnea), a slowing of the heart rate (bradycardia) and even cardiac arrest (asystole).

These are not rare events either and are commonly reported in the newspaper.

There are several common threads in these types of accidents:

• the victims were good swimmers
• the water was cold
• death occurred within a matter of only minutes - much too early for hypothermia to set in
• they were all healthy people
• they were often in shallow water
• the accidents occurred within feet of the shore.

Most important, there was potential help at the scene of the accident, but no one recognized the danger of sudden death from cold shock in an otherwise healthy person. This is the precise reason why standards for wearing lifejackets and/or carriage of liferafts must not be relaxed when operating in cold water. Carriage of EPIRB s (with their 90 minute to 2 hour response time), and the fact that the vessel may be operating in a group or close to shore are not reasons for a waiver.

The clear message is that sudden entry unprotected in cold water is very dangerous and should be avoided wherever possible. This applies to everyone whether commercial operators or recreational boaters.

Stage 3. Long-term immersion or hypothermia

Heat Balance: The Basic Physics

In order to understand the cause of hypothermia, it is important to understand the basic physics of how a human maintains heat balance.

Heat flows down a thermal gradient from high to low temperatures. Thus, in the cold, a thermal gradient is established, down which heat "flows" from the warmer deeper tissues to the cooler tissues near the surface of the body. Heat then escapes from the body to the environment. In normal circumstances in air, the body can exchange heat with the environment via four physical processes: radiation (R), convection (C), conduction (K), and evaporation (E).

R (Radiation). All objects possessing heat, including the body, emit thermal radiation from their surfaces.

C (Convection). This is the process by which heat is exchanged with the environment by the movement of air or water molecules adjacent to the skin, as they move away they are replaced by colder molecules.

K (Conduction). This term is used to describe heat exchange between the skin and surrounding surfaces with which it is in direct contact.

E (Evaporation). Evaporation is the process by which energy transforms liquid to a gas. The heat required to drive this process is removed from the surface of the object on which evaporation is occurring, and it cools.

For body temperature to remain stable in a cool environment, the heat produced by the body at rest or through exercise or shivering (M), must match that lost by R, C, K and E, or combined, R+C+K+E=M.

Several factors influence the amount of heat exchanged by R,C,K, and E. The most common are: the surface area involved in heat exchange; the temperature gradient between the body and the environment; and the relative movement of the fluid (air or water) in which the body is placed. This explains why someone will cool faster if: they are in colder water (gradient); they are partially immersed compared to completely immersed (surface area); they are in fast flowing as opposed to still water (movement of the fluid); they move about compared to staying still (relative movement of the fluid).

In water, heat is conducted to the molecules of water in contact with the skin ("boundary layer"), these molecules are warmed and rise (Convection), and are replaced by cooler ones. Thus, in water only two of the four primary pathways for heat exchange are available, and heat loss is principally by convective and conductive heat exchange. Despite this, a naked individual in cold water will cool approximately four times faster than in air at the same temperature. This is because thermal conductivity of water is 25 times that of air, and its volume-specific heat capacity is approximately 3500 times that of air. Therefore, water has a much greater capacity to extract heat. (The volume-specific heat capacity is obtained by multiplying the specific heat of a substance by its density. It represents the amount of heat required to raise the temperature of a given volume of water by 1° K . At 37° C the volume-specific heat capacity of water is 3431 times that of air.) Furthermore, when in water, unlike air, the surface area available for heat exchange with the environment comes close to 100%. This is the reason why cold water is so dangerous. The corollary to this is that hot water is a very good medium to re-warm hypothermic victims.

After thirty minutes or more of immersion, death may occur from hypothermia. The reason for this is that water has a specific heat 1000 times that of air and a thermal conductivity of about 25 times that of air. Thus, when a body is immersed in water below body temperature (37° C ), it will inevitably cool to hypothermic levels at a rate dependent on:

• Temperature differential
• Clothing insulation
• Rate of agitation of the water
• Body heat production produced by shivering and exercise
• Ratio of body mass to surface area
• Subcutaneous fat thickness
• State of physical fitness
• Diet prior to immersion
• Physical behaviour and body posture in the water

As the deep body temperature falls, humans lapse into unconsciousness. Death may occur in two ways – drowning through incapacitation, and cardiac arrest. Death from drowning will occur in a lightly dressed individual even wearing a lifejacket, approximately one hour after immersion in water at 5° C , or two hours in water at 10° C , or in six hours or less at 15° C (Reference 57).

If the deep body temperature continues to fall, death occurs on average from cardiac arrest somewhere below a body core temperature of 24° C . The lowest recorded survival temperature in an accidental victim is 13.7° C (Reference 51). However, after surgical induction of hypothermia, there has been one reported incident of resuscitation from a body core temperature of 9° C (Reference 122).

Survival predictions were made from experimental data and case histories from shipwrecks. The first classic survival curve was published by Molnar in 1946 (Figure 2) (Reference 115). Included in here was the data from the Dachau prisoners (Reference 4). Survival predictions were later produced by Hall (1972) (Reference 65), and by the Canadian Red Cross from work conducted by Professor Hayward (1975, 1977, 1984) at the University of Victoria (Figure 3) (References 69, 70, 71 and 73).

A later predicted survival curve was published by Hayes et al (1987) derived from Professor Eugene Wissler’s Cold Water Survival Model (Figure 4) (Reference 67). From this and the combination of previous work, Tikuisis (1995, 1997) has published the latest prediction of survival time at sea level based on observed body cooling rates (References 149 and 150).

Figure 2 (After Molnar 1946) – Duration of immersion of shipwreck survivors in ocean waters of diverse temperatures.

 

(The data are from the files of the Bureau of Medicine and Surgery, US Navy. Open circles, sea-water temperature was measured at time of rescue. Black dots, sea water temperature was obtained from the World Atlas of Sea Surface Temperatures on the basis of date and location of shipwreck or rescue. Each point represents the survival of at least one person.)

Figure 3 – Cold Water Survival (Canadian Red Cross)

 

Figure 4: Predicted survival time against sea temperature for different levels of immersed clothing insulation (as derived from Wissler Model, Modified by Hayes, 1987).

 

A summary of current predictive curves is given in Oakley and Pethybridge (1997) (Figure 5) (Reference 126). From this work, it became possible to give advice that survival times could be extended if the survivors stayed still in the water and did not attempt to swim to keep warm. Furthermore, adopting a fetal position with legs together and arms to the side, or folded across the chest prolonged survival time (References 5, 53, 71, 89 and 125). All of these predictive curves are premised on the fact that the person using the curves is prepared to accept the assumption that death is due to hypothermia. They are all based on time to incapacitation.

Figure 5: Predicted periods (in hours) of immersion at different temperatures which are expected to result in "likely death". (After Oakley and Pethybridge (1997)

Water Temperature	Molnar, 1946 (Reference 115)	Keatinge 1969 (Reference 92)	Nunnely & Wissler, 1980 (Reference 115)	Allan, 1983 (Reference 5)	Lee & Lee 1989 (Reference 98)
5° C	2.3	0.9	1.1	1.5	1
10° C	4	N/A	2.6	2.5	3
15° C	N/A	4.5	3	9	7

If the immersed person has survived the initial two stages of immersion, i.e. cold shock and swimming failure, then the next hurdle to face is hypothermia. It is now known that this per se may not be the cause of death. These curves must be used with caution. As Golden pointed out in 1996 (Reference 57), the predicted 50% survival times for fully clothed men in water wearing lifejackets are 1 hour at 5° C , 2 hours at 10° C , and 6 hours at 15° C . Yet these figures are difficult to validate in the laboratory where the body temperature only falls about two or three degrees in the equivalent time. There must be another cause of death. Golden explained that a conscious survivor in a seaway will make the physical effort to keep his/her back against the waves, but when physically impaired through muscle cooling, semi-conscious and with a loss of determined will to survive, both of which occur after a body core temperature drop between 2-3° C , then the survivor turns into the waves and drowns. He also emphasized the point that death will occur much quicker from drowning if a lifejacket is not worn (Figure 6) (Reference 54).

Figure 6: Empirical curve correlating deterioration in consciousness to time, in an immersed body with (B) and without (A) a lifejacket. Courtesy of Prof. Frank Golden.

 

Markle (1991) provides several classic examples of death from hypothermia in water below 15° C in his US Coast Guard Report on lifesaving systems for small passenger vessels (Reference 106).

The argument that liferafts are not necessary because vessels operating near shore in day time can expect other vessels to come to the rescue quickly is not supported, nor is the addition of an EPIRB going to speed up rescue to this type of response time. As already stated, death will occur within 3-5 minutes for those who have not donned a life jacket, or from swimming failure within 30 minutes if not clothed properly and supported by a lifejacket. Markle (1991) came to precisely the same conclusion.

Stage 4 - Post-rescue collapse

Up to twenty percent of immersion deaths occur during extraction from the water, or within hours after rescue (Reference 57). This was first noticed in 1875, by Reinke, a police surgeon in Hamburg. He recorded cases of sailors who had fallen into the canals and harbour and died within 24 hours of being rescued (Reference 55). During the Second World War, the Germans and Allies noted that some of those who were rescued alive, died shortly afterwards. Matthes (Reference 109) noted how ditched German aircrew who had been conscious in the water and aided in their own rescue, became unconscious and died shortly afterwards. McCance et al, (1956) (Reference 108) found that seventeen percent of those shipwrecked survivors rescued from the water at 10° C or less died within 24 hours of rescue. None of the people rescued from water above 20° C died.

When the Wahine Ferry sank in 1969 in Wellington Harbour, Mercer (Reference 113) reported that, of the 51 lives lost, twelve were alive on rescue, but died shortly afterward. In the 1994 Estonia accident, at least one person who was noticed to be alive in the water, lost consciousness when in a helicopter hoist, fell back into the sea and died. An extensive list of post rescue collapse incidents is reported in Golden’s articles on shipwreck and survival (Reference 55) and Golden and Hervey’s article on the after-drop and death after rescue from immersion in cold water (Reference 53).

The Initial Responses to Immersion (Stage 1 and Stage 2) – New Scientific Information Since 1975

It has now become clear that over half of the immersion-related deaths occur during the first two stages of immersion, i.e. cold shock and swimming failure. However, as stated previously, investigators still concentrate on the cause of the marine accident and not the precise cause of an individual’s death. It is still hard to accurately document at what stage of the immersion death occurred. This is because little history has been gathered from survivors or by investigators. It is only possible, to a limited degree, to estimate the cause of death from a newspaper report or the scant information in the accident investigation. The problem is further compounded by the fact that such a good job has been done educating people on the dangers of cold water, immersion and hypothermia, that even the pathologists now list the cause of death as hypothermia, even though the cold, wet body on their autopsy table actually died from cold shock or swimming failure and drowning.

Although cold shock or an increased respiratory response to cold water has been known for many years (Falk, 1884) (Reference 45), the practical significance of this response has only really been evaluated in terms of its practical importance in the last 20 years. When considering at what water temperature protection should be provided against the initial responses to cold water immersion, it is now known that the cold shock response begins at water temperatures below 25° C (Reference 90) and peak at a temperature between 10-15° C (References 154 and 155). This is in part, the explanation for deaths that occur in water as high as 15° C long before standard survival curves would predict. It is now thought by many that the pressing threat to otherwise healthy individuals is the respiratory distress evoked by immersion and the consequent inability to control breathing and breath hold.

Swimming has a massive impact on the rate of body cooling and can increase the rate between 30-40% (Reference 92). Tipton et al (1999) (Reference 160) studied the deterioration of swimming performance after the subjects had adapted to the stage 1 cold shock respiratory responses. All ten competent swimmers completed a 90-minute swim in 25° C water; eight completed the swim in 18° C water. In 10° C water, five swimmers completed 90 minute swims, four were withdrawn between 22 and 50 minutes close to swim failure and one was withdrawn at 61 minutes close to swim failure. Stroke rate and length were similar in 25° C and 18° C water throughout the swims, but in 10° C water the stroke rate was increased and the stroke length decreased. These changes were most pronounced in those close to swim fatigue. Stroke length decreased by 50% during the last 30 minutes for the swimmer who reached swim failure in 61 minutes.

Coincident to this, the average swimming angle increased from an average of 18º at the start of the swim to 24º at the end of the swim. The swimmer who reached swim failure finished with a swim angle of 35º. After 15-30 minutes in 10° C water, swimmers’ fingers were splayed and started to flex. At the end of the swims, swimmers reported that it became increasingly difficult to straighten their limbs and coordinate swimming movements. Grip strength was not altered by swimming in water at 25° C , but in water at 18° C and 10° C , it was significantly decreased by 11% and 26% respectively.

Wallingford et al (2000) (Reference 170) investigated the factors which limit cold water swimming distance while wearing a personal flotation device. Five female and twelve male subjects took part in a swim in 14° C water. The subjects swam an average of 889 metres before swim failure. There was no correlation between distance swum and percentage body fat, aerobic fitness and abdominal skinfold thickness. However, those who swum the greatest distance had a significantly larger tricep skinfold thickness.

Wallingford et al. agreed with the conclusion made by Giesbreicht (1995) (Reference 49) that the majority of the decrement in arm performance is due to the local cooling of arm tissue and not due to hypothermia. Wallingford’s study did not support the assumption made by Hayward et al (1975) (Reference 70) that hypothermia could be responsible for the inability to swim in cold water while wearing a personal flotation device. If Hayward’s prediction was correct, the swimmers would have covered a distance of 2058 metres before incapacitation. This was more than double the distance of 889 metres covered by the subjects long before incapacitation from hypothermia (end average core temperature of 35.8° C ).

Markle (1991) (Reference 106) correctly noted that persons in the water with and without lifesaving equipment died at a much higher rate than predicted by the estimated survival graph. This supports Golden’s theory that many victims drown during the cold shock and swimming failure stage of immersion, not from hypothermia per se. Even if they survive long enough to cool, cold-induced muscle incapacitation can prevent their keeping their backs to the waves, and thus their oro-nasal cavities clear of water, sometime after their body core temperature is reduced 2-3° C . This is why it is essential to wear a lifejacket with good sea keeping properties, i.e. self-righting, good freeboard and a face shield to protect from hypothermia.

Markle further concluded that "The present requirements for lifejackets, life floats and buoyant apparatus have proven adequate in all studied casualties where water temperature was 15° C or less". This might have been the case in this study, but it is still possible to die from hypothermia and post rescue collapse as in the case of the Lakonia in 1965 that sank in 17.9° C water off Madeira (Reference 91).

The provision of a buoyant apparatus in which the survivor is basically floating with head only out of the water clinging to a becketed line in water below 15° C is only a last ditch measure if everything else has failed. Drowning is very likely from cold shock and swimming failure, in the short term, and hypothermia and post rescue collapse in the long term. The colder the water, the greater the chance of death. Again, as Markle clearly pointed out, in the case of the Cougar accident, the two people who managed to get themselves on top of a buoyant apparatus were the two not to be hospitalized. The remainder had to remain clinging to it in water at 13° C , three died. Similarly, in another case referred to by Markle (Zephyr ll accident), if the device had been a liferaft instead of a buoyant apparatus, the person without the lifejacket would have been able to board it and would have survived the few minutes in the water. In this accident, eight of the survivors got separated from the boat. They decided to swim to an island, only one was alive six hours later when he called for help when almost ashore.

A Typical Case Where Death was Incorrectly Attributed to Hypothermia

Paradoxically, as previously stated, we have done a very good job of educating the public about hypothermia. As a result, local rescuers, police, the Red Cross, coroners and pathologists always assume that someone who has been pulled out of cold water drowned form hypothermia, yet this often is not the case. Because this assumption has been made, little further questioning has been conducted to find out precisely how, when and where the victim met his/her demise. The Ocean Ranger sank in near freezing water on the Grand Banks off Newfoundland in February 1982 with the loss of all 84 men. No one was outfitted with a survival suit, although some wore lifejackets. The cause of death was attributed to drowning from hypothermia, yet from the testimony available, many died after only a matter of a few minutes in the water.

Below is the testimony from the Master of the Seaforth Highlander (Reference 118).

Death obviously in this case was caused by cold shock and possibly swimming failure, but certainly not hypothermia.

Breath Holding Ability and Ability to Control Breathing Rate

This is very critical for all who abandon ship into cold water. If they abandon dry shod into a liferaft, there is no problem. However, if they abandon ship into cold water, unless they are mentally and physically prepared for the cold shock, are protected with a survival suit, a lifejacket and a spray hood, they may drown in the immediate abandonment due to the inability to control breathing in the first three minutes of immersion. It is not just a problem of not being able to breath hold; if you are in choppy water, there is an inability to coordinate and control breathing with wave splash. This is a typical scenario for passengers on tourist vessels in Canada’s lakes and rivers in spring and early summer.

Sterba et al (1979) (Reference 142) investigated breath holding capability of humans in water ranging from 15° C -35° C . They concluded that breath holding ability at 15° C was approximately 30% of the nonimmersed values.

Hayward et al (1984) (Reference 74) showed clearly that there is an inverse relationship between water temperature and breath hold ability. Thus, for abandonment in 25° C water, average breath holding is 38 seconds, whereas for 15° C , 10° C and 5° C water it is 28, 24, and 19 seconds respectively. They concluded that breath holding time in water below 15° C was 25-50% of the presubmersion level. Their predictive curve was recently validated at the higher end of the scale by Cheung et al (2001) (Reference 35) in 25° C water following a breath holding experiment. Two hundred and twenty eight subjects participated and the average breath hold time was a mean of 39.8 ± 21.1 seconds.

Potential for Cardiac Arrhythmias

Tipton (1989) (Reference 153) had already documented the initial cardio-respiratory responses to immersion in cold water, i.e. the massive increase in heart rate and blood pressure within the first three minutes of immersion. Then in 1994, Tipton et al investigated the cardiac responses to submersion in water of 5° C and 10° C (Reference 157). Ectopic arrhythmias (irregular heartbeats) were observed in 11 of the 12 subjects in 29 of the 36 submersions. These occurred immediately after breaking of breath hold, i.e. just at the time after jumping into the water and having to take a breath. They were benign in most cases, (i.e. they were of short duration, supraventricular in origin and producing no symptoms). However, this may not be the case for an aging population of tourists that may have to abandon a vessel in cold water, such as the St. Lawrence River or one of the Great Lakes. For those with a potential heart conduction defect, the heart is likely to be very susceptible to sudden immersion in water of 10° C , resulting in a cardiac arrest or death. Sudden immersion in cold water to the neck makes the heart much more susceptible to arrythmias, due to an increase in output of the stress hormones (i.e. Adrenaline, Noradrenaline). The frequency of these arrhythmias is higher when the face is immersed.

Manual Dexterity

There has now been more research done on loss of tactility in cold water during the first 10-15 minutes of immersion (Reference 78). During this time, the cold water renders the limbs useless, and particularly the hands. It can become impossible to carry out any self-rescue procedures. This only enhances the possibility of perishing before hypothermia is established.

The ability to do such tasks as activate the life jacket inflation device (if fitted), climb into a life raft, cling to a becketted line or activate a flare depends on manual dexterity and grip strength. The ability of muscle to produce force is reduced when its temperature falls below 27° C . This can occur in as little as 20 minutes in water at 12° C (Reference 16). Vincent and Tipton (1988) (Reference 151) showed that the maximum voluntary grip strength ( MVGS ) of subjects who immersed their unprotected hands or forearms in 5° C water was reduced by 16% and 13% respectively, and that wearing a glove significantly reduced the MVGS by 16% in air and with the hand glove and water immersion combination, the reduction was 31%. Research has also shown that hand grip strength was reduced by up to 60% (References 36, 37, 60 and 81), manual dexterity was reduced by 30% (References 48, 95 and 148) and speed of finger flexion was decreased by 15- 25%. A recent study by Heuss et al (1995) (Reference 78) identified minimum hand temperature criteria for safety and performance – local skin temperature 15° C , nerve temperature 20° C and muscle temperature 28° C .

The sinking of the Hudson Transport on Christmas Day 1981 in the freezing water off the Gulf of St. Lawrence is a classic example where cold extremities contributed to the death of five seamen (Reference 80).

Should Passengers Wear Lifejackets Prior To Abandonment?

This question was raised after several rapid sinkings occurred. Particular accidents cited have been the loss of the MV George Prince (1976) (Reference 163) in the Mississippi River where 76 people died, the loss of the USCG Cuyahoga (1978) (Reference 164) in Chesapeake Bay where 11 people died; the loss of the Marchioness (1989) (Reference 105) in the River Thames, UK , where 51 people died; and the loss of the MV Miss Majestic (1999) (Reference 165) on Lake Hamilton, Arkansas where 13 people died. The problem in each of these accidents was that many of the people were trapped between decks. The wearing of an inherently buoyant lifejacket would have further hampered their escape if it was possible. Nevertheless, for those who found themselves in the water and in the dark in two of the accidents, a lifejacket was critical to their survival.

If one is therefore going to regulate that passengers must wear a lifejacket on a passenger-carrying vessel that does not have the ability to carry a liferaft, then the lifejacket must be an inflatable one. The modern inflatable lifejacket is an excellent piece of life-saving equipment; it is comfortable, unobtrusive and very reliable. The Europeans have been using them for recreation and commercial boating operations on their lakes, rivers and canals for years. Canada has simply been slow in effecting new legislation for approval and it is only in the last five years that they have started to come into general use.

The argument from ship’s operators that they are expensive to purchase and maintain is only partially true. The fact is that once operators start to use them and passengers become familiar with them, then the confidence in their merit will go up, the price (due to a higher demand) will go down, and maintenance costs will correspondingly go down due to the general public starting to respect a very good piece of equipment that will potentially save their life. The two children in the True North II accident would have likely been alive and well today if they had worn a good inflatable lifejacket as they stepped on board the boat.

Summary of Chapter 1

This chapter discusses essentials to know about the applied physiology of a sudden cold water immersion accident.

• Up until fifty years ago, no one really understood the reason why people suddenly immersed in cold water died. It was attributed to an inability to stay afloat and vague terms such as "exposure". Nor was anyone particularly concerned about the steady cost of life. It was simply accepted as an occupational hazard and fate.
• Any early attempt at saving ship wrecked mariners was to provide them with flotation in rather than out of the water.
• Death may occur from one of the four stages of immersion:
• Stage 1 Cold shock (3 – 5 minutes)
• Stage 2 Swimming failure (3-30 minutes)
• Stage 3: Hypothermia (after 30 minutes)
• Stage 4: Post rescue collapse (during or hours after rescue)
• Although the four stages have been known since World War ll, stages 1 and 2 were considered only of academic interest. As a result, regulators, teaching establishments and survival suit manufacturers all concentrated their efforts on protecting the human from hypothermia. Indeed, in this regard they have done a very good job.
• Even though there are well established teaching programs, good regulations and much improved life saving equipment, there are still in the order of 140 000 open water deaths each year. What has been overlooked is the significance of the first two stages - cold shock and swimming failure as a cause of death. The severity of the effects of cold shock is directly proportional to the water temperature peaking between 10-15° C .
• The layperson and accident investigators are often surprised that some people do not survive a lengthy immersion. Theoretically they are within the "safe" boundaries of one or more of the survival curves that have been developed to predict death from hypothermia. These people do not die of hypothermia per se. They die from a variety of problems in which moderate hypothermia is enough for them to lose their physical ability and mental determination to keep their backs to the waves. Thus, they inhale the next wave and die from drowning in spite of wearing a life jacket.
• From all the combined research on cold water accidents and scientific research, it has become clear that sudden immersion in cold water, i.e. below 15° C is very dangerous, it should be avoided if at all possible. It has now been shown that a person’s swimming ability in warm water bears no relationship to that in cold water. A conscious decision to swim (and rescue oneself) or stay floating still in the water (and be rescued) should not be taken lightly without assessing the pros and cons. In water below 15° C , crew and passengers must abandon ship dry shod. If it is not practical to stow a liferaft on small vessels, then passengers must wear a modern inflatable lifejacket at all times.

 

 

1) Throughout the report, buoyancy will be reported in imperial pounds, kilograms or Newtons depending on the year of the test and the current nomenclature. (1 kg = 2.2 lbs = 9.8 Newtons)

 

 

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