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Hypothermia

In addition to absorbing three hours of spectacular entertainment, the millions who've recently viewed James Cameron's epic, Titanic, have been given a graphic reminder that the human body can't survive for long in extremely cold water with or without a life jacket.

Thankfully, water temperatures in the Bay Area aren't as severe as in the North Atlantic. Nevertheless, temperatures here are life threatening year round. With this sobering fact in mind, it's advisable if not essential for every Northern California sailor to be well acquainted with cold-water survival techniques.

'Immersion hypothermia' is the medical term for one of the dire consequences of falling into cold water. The most dreadful consequence, obviously, is drowning or near-drowning. The definition of cold water is variable, but the significant risk of immersion hypothermia is in water 77 degrees F or colder. San Francisco Bay temperatures never get higher than the mid-50s, even in the summer months.

It's estimated that half of all socalled 'drowning' victims actually die from the fatal effects of cold water, which robs the body of heat 25-30 times faster than air. When you lose enough body heat to make your temperature subnormal, you become hypothermic. In the Titanic tragedy, the official cause of death of the 1,489 souls who perished in the 32-dgree water was listed as 'drowning', but the more probable cause was immersion hypothermia.

What actually happens when you fall overboard into 50-degree water? When the water first hits you, it's cold but not paralyzing.

If you're wearing a PFD and you survive the first few minutes in the water, there's a good chance of surviving for up to four hours. But it can be extremely variable, depending on the sea state, your physique, your conditioning, your clothing, and your behavior in the water.

In any case, the first minutes in the water are critical. Although most people try to hold their breath, most experience an overwhelming impulse to gasp for air - a gasp reflex - which causes involuntary mouth opening and deep inhalation. Looking at the mechanics of this phenomenon presents a strong argument for wearing a PFD, since one of two things will happen if you are actually under water when that gasp occurs: in a small number of people roughly 10% of us
the larynx goes into spasms and nothing can enter the lungs; suffocation may then occur. In the rest of us there is an almost immediate flooding of the lungs and drowning begins. Loss of consciousness rapidly follows and soon death. As Sebastian Jungar wrote in his recent book The Perfect Storm, "The panic of a drowning person is mixed with an odd incredulity that this is really happening. Having never done it before the body and the mind do not know how to die gracefully. The process is filled with desperation and awkwardness. 'So this is drowning,' a drowning person might think. 'So this is how my life finally ends."'

As if the gasp reflex were not frightening enough, there is yet another reflex, which for some can be even worse - cold water causes a precipitous rise in blood pressure and heart rate. In some, this creates such a strain on the heart that it literally stops pumping blood. Unconsciousness and death occur almost instantly.

For those who have had the good fortune of surviving those first minutes without immediately drowning or having a cardiac arrest, there is now the problem of staying alive long enough to be rescued. But the cold water is making it more and more difficult. Blood is rapidly shunted away from the surface of the body in order to protect vital organs such as the kidneys, liver, brain, and heart. Uncontrollable shivering begins. Muscle coordination and strength wane. Studies have shown that after the first five minutes in 50-degree F water, muscle strength decreases by 1.8% per minute. Disorientation and confusion begin. It becomes harder and harder to think straight. The hands are now numb and unable to grip. The legs are so weak that any attempt to swim or even tread water is useless. And even if the sea is moderately calm and the PFD is maintaining the head above water, the constant splashing of small waves makes it impossible to keep water out of the nose and mouth. If rescue does not happen soon, death is inevitable.

Now that I've painted such a fatalistic picture, let me try to get you out of this mess. Fortunately, the whole issue of cold-water immersion has been extensively studied and from those studies we can give good advice based on solid evidence. But first of all, it is important to understand that there is at least one factor over which you have little control - your physique. Children are especially prone to hypothermia because of their high skin surface to body mass ratio. And for the same reason, tall, skinny people are far more susceptible to hypothermia than short, fat, or highly muscular types. For example, in July of 1993 a man fell off a ferry into the 61-degree water of British Columbia's Strait of Georgia. He was not wearing a PFD. The predicted survival time in that water is around five hours. But he drifted overnight, over eight hours, and was rescued in the morning, He was found to be only moderately hypothermic. And, although the media heralded this event as a "miracle," it could better be described as not that unusual - the man was a well-muscled 6'4", 220-pounder. His bulk of muscle and fat made him a slow cooler, and he survived.

But what factors can you control if you do happen to fall into cold water? Above all, don't panic! Panicking exhausts your reserve energy and strength. There is a physiological reflex to hyperventilate in cold water. Try to consciously slow your breathing. Hyperventilation can quickly produce muscle cramping and spasms.

And then try to remember the followIng:

• Keep wearing all your clothing. Do not remove anything except possibly your sea boots if they are weighing you down and pulling you under.
  
• Button, buckle, zip and tighten collars, cuffs, shoes and hoods. Do this quickly, before your hands are numb and muscle strength is gone. Cover your head if possible. A layer of water trapped inside your clothing will be slightly warmed by your body and will help insulate you from the colder water, thereby slowing body heat loss.
• If you were not wearing a PFD when you entered the water, there is a chance an alert crew has tossed one overboard - find it and put it on immediately.
• Look for a nearby rescue line or float and swim to it if at all possible.
• At this point devote all your efforts to getting out of the water and continue to act quickly before you lose full use of your hands and limbs. Climb onto anything floating. The object is to get as much of yourself out of the water as possible. Even though you are now exposed to wind and spray, you will not lose heat as rapidly as you would in the water. Wind-chill is not anywhere near as lethal as staying in the water.
• Do not attempt any further swimming unless it is absolutely necessary to reach a nearby boat or another person. Unnecessary swimming pumps out warmed water between your body and your clothing, causing new cold water to take its place. Excessive movement of your arms and legs can reduce your survival time by as much as 50%.
• If there Is no floating object nearby to hold onto, then assume the Heat Escape Lessening Position (H.E.L.P) by holding knees to chest. Wrap arms around legs and clasp hands together.
• If there are others in the water, huddling together can extend survival time up to 50%.
• Continue to remain as still as possible. It may be painful but remember that intense shivering and severe pain are natural body reflexes in cold water, which will not kill you, heat loss will.

If you ever find yourself onboard a vessel when someone goes overboard, here are some things to keep in mind:

• The first principle of rescue is to get the victim out of the water as soon as possible. Immediately throw anything into the water that the person might be able to wear or hang onto. Make sure that at least one crewmember watches the victim at all times. Get the boat back to the person using whatever technique you have practiced in your man-overboard drills.
• After the first 5-10 minutes do not expect the victim to be able to get out of the water unassisted. After 15 minutes, assume the victim is already significantly hypothermic and will be helpless to assist in his own rescue.
• Remove the victim from the water gently and in a horizontal position. Even mildly hypothermic victims, if forced into a vertical or standing position, can suddenly drop their blood pressure and lapse into unconsciousness.
• Gentle handling of the victim is extremely important since excessive jostling can produce lethal heart arrhythmias in a moderately hypothermic person.
• If the victim is unconscious, not breathing, and has no pulse, CPR must be performed. But before you start CPR you must make absolutely sure that there is neither pulse nor breath. In severely hypothermic victims, respirations and pulse may be slow, shallow, and difficult to detect. Therefore, spend at least a minute in assessment before commencing with CPR.
• You may have to continue CPR for a long time. A few years ago, a severely hypothermic 25-year-old woman was rescued in the Sierras. During transport she suffered a cardiopulmonary arrest but was successfully resuscitated after three hours of CPR. After recovery from the water and initial management of any life-threatening emergencies, the objective is the prevention of further heat loss.
• Minimize physical activity. The physiological process known as 'after-drop' produces further cooling of the body long after removal from the water. This can be aggravated by physical activity where the cool body surface blood is suddenly mixed with the warmer core blood. Experiments on moderately hypothermic volunteers have demonstrated a three-fold greater after-drop during treadmill walking than when lying still.
• Remove wet clothing, gently dry the skin, then wrap the victim in a dry, insulated blanket, rescue bag, or sleeping bag. If further heating of the victim is warranted, then the safest method is 'buddy warming' where a crewmember joins the victim in the blanket or sleeping bag. The buddy should concentrate on lateral chest to lateral chest contact. Lower extremity contact is unnecessary so pants don't have to be removed. (Yes, you can try this at home.)
• Avoid using heating pads or hot water bottles because of the high risk of further skin damage. Hypothermic skin is injured skin and there have been cases of third degree burns resulting from the use of heating implements. If you feel you absolutely must use such devices, it is mandatory that they not be in direct contact with skin. Use clothing or blankets as a barrier.
• Do not give hot food or liquids unless the victim is fully alert and awake. There is a strong vomiting reflex in hypothermia. The drinks and food may help the morale of the victim but are only minimally effective in raising the temperature.
• No alcoholic drinks, cigarettes, or coffee in any hypothermia situation.

The case of the SS Empire Howard which sank in 29-degree water in the Arctic Ocean illustrates the delicate nature of the post-rescue warming process: "I was the last man to be picked up," recalled Captain H.J.M. Downie. "Everyone was conscious when taken out of the water, but many of the men lost consciousness when taken onto the warmth of the trawlers. Nine of the men died on board soon after being picked up. We were all given a small mouthful of spirits and this made us sleep. These unfortunate men went to sleep and did not wake up again."

Ultimately, any person who has suffered anything more than a very minimal cold water immersion should be brought to medical attention as soon as possible. There are many case histories of death occurring hours after the incident.

As someone once said, the best way to avoid drowning at sea is to make damn sure you never fall overboard in the first place. So be careful out there.

- kent benedict, md

Kent Benedict is a board certified emergency physician and is the Chief Medical Officer for the Cal Maritime Academy's training ship, the Golden Bear.

This story was reprinted from the the March 1998 issue of Latitude 38. To order a copy (complete with black & white photos), use the subscription order form, and specify the 3/98 issue, or just drop us a note with a check for $7 to Latitude 38, Attn: Back Issues, 15 Locust Ave., Mill Valley, CA 94941.

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