Latitude 38 Features: Hypothermia (2023)

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Latitude 38 Features: Hypothermia (1)

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Latitude 38 Features: Hypothermia (2)

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.

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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.

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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."

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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.

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Latitude 38 Features: Hypothermia (3)

This story was reprinted from the the March 1998 issue of Latitude38. To order a copy (complete with black & white photos), use the subscriptionorder form, and specify the 3/98 issue, or just drop usa note with a check for $7 to Latitude 38, Attn: Back Issues,15 Locust Ave., Mill Valley, CA 94941.

Please note: If the actual issue is no longer be available, we willstill be able to make photocopies or PDFs of it.


What temperature is hypothermia? ›

Definition. Hypothermia is dangerously low body temperature, below 95°F (35°C).

Can you get hypothermia in 35 degree weather? ›

Hypothermia is most likely at very cold temperatures, but it can occur even at cool temperatures above 40 degrees Fahrenheit if a person becomes chilled from rain, sweat, or submersion in cold water.

What does mean hypothermia? ›

Hypothermia (abnormally low body temperature) and frostbite are both dangerous conditions that can happen when a person is exposed to extremely cold temperatures.

What causes of hypothermia? ›

Hypothermia is a potentially dangerous drop in body temperature, usually caused by prolonged exposure to cold temperatures. The risk of cold exposure increases as the winter months arrive. But if you're exposed to cold temperatures on a spring hike or capsized on a summer sail, you can also be at risk of hypothermia.

When does hypothermia start? ›

Hypothermia occurs when the body temperature is below 35°C. This can develop with prolonged exposure to temperatures under 10°C, or after prolonged immersion in cold water of less than 20°C. A person with hypothermia may not be aware of their need for medical attention.

Do I have hypothermia? ›

You have hypothermia if your body temperature drops below 95°F. Hypothermia also can occur in temperatures that are not bitterly cold, like those above 40°F. This is usually due to a person being wet, sweaty, or trapped in cold water.

How cold does it have to be to risk hypothermia? ›

Hypothermia can occur when you are exposed to cold air, water, wind, or rain. Your body temperature can drop to a low level at temperatures of 10°C (50°F). Your body temperature can drop even if it is warmer than 10°C (50°F) if you are out in wet and windy weather.

How cold does it have to be outside for hypothermia? ›

And while the weather has been unusually warm thus far in much of the country, temperatures need not be at freezing, or even very low, for hypothermia to occur. Most cases occur in air temperatures of 30 to 50 degrees. But people can succumb to overexposure even at 60 or 70 degrees.

At what water temperature can you get hypothermia? ›

Typically people in temperate climates don't consider themselves at risk from hypothermia in the water, but hypothermia can occur in any water temperature below 70°F.

Are there 4 types of hypothermia? ›

One scale breaks cases into three categories of mild, moderate, and severe hypothermia, with core body temperature readings and symptoms being the differentiators between the three categories.

Is hypothermia hot or cold? ›

Shivering and feeling cold or numb are warning signs that the body is losing too much heat. Simple ways to prevent hypothermia include: Avoid prolonged exposure to cold weather. Be alert to weather conditions that may increase the risk of hypothermia and act accordingly.

What is an example of a hypothermia? ›

Your body temperature can drop quickly and significantly. Exposure to colder-than-normal temperatures can also cause hypothermia. For example, if you step into an extremely cold, air-conditioned room immediately after being outside, you risk losing too much body heat in a short period.

Who is at risk of hypothermia? ›

For people most at risk of hypothermia — infants, older adults, people who have mental or physical problems, and people who are homeless — community outreach programs and social support services can be of great help.

How do you stop hypothermia? ›

  1. Be gentle. When you're helping a person with hypothermia, handle him or her gently. ...
  2. Move the person out of the cold. ...
  3. Remove wet clothing. ...
  4. Cover the person with blankets. ...
  5. Insulate the person's body from the cold ground. ...
  6. Monitor breathing. ...
  7. Provide warm beverages. ...
  8. Use warm, dry compresses.
5 Mar 2022

What are the 3 stages of hypothermia? ›

The signs and symptoms of the three different stages of hypothermia are: First stage: shivering, reduced circulation; Second stage: slow, weak pulse, slowed breathing, lack of co-ordination, irritability, confusion and sleepy behaviour; Advanced stage: slow, weak or absent respiration and pulse.

How long does hypothermia last? ›

In the air, hypothermia can develop in as little as five minutes in temperatures of minus -50°F/-45.5°C in people who are not dressed properly and have exposed skin. At -30°F/-34.4°C, hypothermia can occur in about 10 minutes. Death can occur in under an hour in extremely cold conditions.

Can you get hypothermia indoors? ›

Hypothermia can happen indoors

It's possible to lose a dangerous amount of body heat inside your own home. Hypothermia can happen indoors in as little as 10 or 15 minutes if the temperature settings are cold enough. Not having any heat in your home in the winter can be very dangerous.

How long does it take to get hypothermia in 38 degree water? ›

At a water temperature of 32.5 degrees, death may occur in under 15 - 45 minutes. At a water temperature of 32.5 to 40 degrees, death may occur in 30 - 90 minutes. At a water temperature of 40 to 50 degrees, death may occur in 1 - 3 hours. At a water temperature of 50 - 60 degrees, death may occur in 1 - 6 hours.

Can cold showers cause hypothermia? ›

Any kind of exposure to extreme cold comes with the risk of hypothermia, and ice baths are no exception.

How long does hypothermia stay in cold water? ›

In water that is around the freezing point, a person is likely to survive only 15 to 45 minutes with flotation and possibly up to an hour or so with flotation and protective gear before the brain and heart stop (Table 1).

What are 5 facts about hypothermia? ›

What is hypothermia?
  • You get hypothermia when you're in a cold place for a long time.
  • Hypothermia is more likely if it's windy, you're in cold water or wet, or you can't move around to keep warm.
  • At first, hypothermia makes you shiver.
  • As hypothermia gets worse, you become confused and lose awareness.

What are the types of hypothermia? ›

Types of hypothermia
  • Acute or immersion hypothermia occurs when a person loses heat very rapidly, for example by falling into cold water.
  • Exhaustion hypothermia occurs when a person's body is so tired it can no longer generate heat.
  • Chronic hypothermia is when heat loss occurs slowly over time.

What are the two types of hypothermia? ›

There are two types of hypothermia, and these are known as primary and secondary. Primary hypothermia is caused by an external environmental stressor alone and the absence of any medical conditions that could cause a disruption in thermoregulation.

How does hypothermia affect the brain? ›

Hypothermia progressively depresses the CNS, decreasing CNS metabolism in a linear fashion as the core temperature drops. At core temperatures less than 33°C, brain electrical activity becomes abnormal; between 19°C and 20°C, an electroencephalogram (EEG) may appear consistent with brain death.

What medications cause hypothermia? ›

Hypothermia is a rare, but potentially fatal adverse effect of antipsychotic drug (APD) use.

What causes death in hypothermia? ›

Although no cellular injury occurs as a result of hypothermia unless frostbite occurs, severe hypothermia often results in death due to cardiac dysrhythmia, usually ventricular fibrillation (6).

Can you live from hypothermia? ›

"Hypothermia is a medical emergency when your body loses heat faster than it can produce it. As your body temperature drops, your heart, brain, and internal organs cannot function. Without aggressive resuscitation and rapid rewarming, you will ultimately not survive," explains Dr.

Does hypothermia make you sleepy? ›

Your body can also lose heat faster than you can produce it. That can cause hypothermia, or abnormally low body temperature. It can make you sleepy, confused, and clumsy. Because it happens gradually and affects your thinking, you may not realize you need help.

What does hypothermia feel like? ›

Hypothermia is a dangerous condition involving low body temperature. Symptoms such as shivering, pale skin, and fast heart rate indicate a person's core body temperature has dropped below normal. The stages of hypothermia range from mild to severe.

Can hypothermia occur in 14 degree weather? ›

Contrary to popular belief, the air temperature does not have to be below freezing for hypothermia to occur. Hypothermia strikes anytime weather conditions, including rain, or water temperatures lower a person's core body temperature below 95° F.

What is the coldest temperature a body can handle? ›

The lowest temperature that the human body can survive is 96 degrees Fahrenheit. This is the temperature where the body continues to function normally. Any temperature below 96 degrees Fahrenheit interferes with normal organ functions and can lead to hypothermia, shivering, and pale skin.

What are the 2 effects of hypothermia? ›

Signs and symptoms of hypothermia include: Shivering. Slurred speech or mumbling.

How long can hypothermia last? ›

In the air, hypothermia can develop in as little as five minutes in temperatures of minus -50°F/-45.5°C in people who are not dressed properly and have exposed skin. At -30°F/-34.4°C, hypothermia can occur in about 10 minutes. Death can occur in under an hour in extremely cold conditions.

Can you get hypothermia in 40 degree water? ›

Typically people in temperate climates don't consider themselves at risk from hypothermia in the water, but hypothermia can occur in any water temperature below 70°F.

What temperature can humans not survive? ›

While most researchers agree that a wet-bulb temperature of 95 °F is unlivable for most humans, the reality is that less extreme conditions can be deadly too. We've only hit those wet-bulb temperatures on Earth a few times, but heat kills people around the world every year.

What temp is harmful to humans? ›

The wet-bulb temperature that marks the upper limit of what the human body can handle is 95 degrees Fahrenheit (35 Celsius). But any temperatures above 86 degrees Fahrenheit (30 Celsius) can be dangerous and deadly.

What temperature humans Cannot survive? ›

Anything above is called fever, which can lead to hyperthermia in a heat wave condition. It could be fatal. It is commonly held that the maximum temperature at which humans can survive is 108.14-degree Fahrenheit or 42.3-degree Celsius. A higher temperature may denature proteins and cause irreparable damage to brain.


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