Hypothermia and the SCUBA Diver
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Hypothermia is a topic that should concern all rescue personnel. When we are exposed to cold for prolonged periods of time the body will be directly affected. As I’m sure you know, we lose 60% of our body heat through our head and another 20% through our hands and feet. The wind chill factor also greatly affects those who are exposed to it.
However, in-water personnel lose body heat 25 times faster than those on land. Tenders and boating personnel who are on or near the water tend to lose body heat 10-15 times faster than rescue crews who work away from the water.
We must be aware that cold or hypothermic problems are important to water-related rescue personnel. Invariably, rescues seem to occur in the most adverse conditions, such as cold or stormy weather. It is easy for us to become victims of these elements because we often are not totally prepared for these situations.
Many rescue teams have poor fitting wet and dry suits or do not wear their gear. Too often we hear rescue personnel say: “I forgot my hood. Never mind, I’ll dive without it.”; or “I don’t like wearing my mitts or gloves so I’ll dive without them.” Remember, over 80% of our body heat is lost through our head, hands, and feet. That is a large amount of heat and energy, and our body temperature is always “going down.”
When our hands are left unprotected they will become cold, numb, and useless. Movements become uncoordinated and jerky. How will we be able to inflate our BC (buoyancy compensator) or release our weightbelt? How will we be able to use our hands to pull a safety line or unclip the snaps on our equipment when we can’t make our fingers function?
Our normal body temperature is 98.6°F (37°C). According to Dr. Glen Egstrom of UCLA, we have a “comfort zone.” That is, if our body temperature rises or falls one degree Fahrenheit, our body will feel only minimal negative effect.
However, if our temperature falls below this comfort zone, we begin to shiver. Shivering can last anywhere from a few seconds to many minutes and is an initial sign of hypothermia. It is one of the first symptoms we experience that tells us we are getting cold and that our body temperature is “going down.” It is unfortunate that so many of us seem to ignore this obvious signal.
When the body begins to move out of this comfort zone both divers and tenders find that their mind and fine mobile movements become hindered. They can no longer rely on their hands to perform the way they need them to. Their minds are telling them that their fingers are doing the job, but, in fact, their fingers are crumpling because they can no longer function. When hypothermia begins, they might not even be able to remove a glove from their own hand.
Many of us have persevered through the shivers and continued to dive and work. Surprisingly enough, many times the shivering stops. Unfortunately, this is where the trouble really begins, and we slip into the down side of hypothermia.
As hypothermia increases, our ability to think is drastically impaired. We refer to this as “It’s All Going Down”—that is, our body temperature, our performance ability, our thought process, and our diver are all “going down.”
Hypothermia creeps up on us with little warning. We often do not realize the detrimental effect it has on our bodies until it is too late. When we are cold, the simplest task such as removing a glove or trying to write is not easy. In fact, it is almost impossible. Our brain tells us what it wants us to do, but our physical response is clumsy and awkward. Even when our hands begin to warm up they become extremely painful and we are more reluctant to use them.
Tests have proven that tiny muscle groups, such as those in our fingers, become inoperable in cold water. These are the muscles we rely on so heavily to do all the work. The diver could be so cold that he could not use his fingers to push the button on his power inflator hose that is connected to his BC. It’s also possible that his mouth and lips will not be working well enough for him to blow air into the BC.
photos by Thomson
The larger muscle groups, such as those in the forearm, maintain most of their functions. However, it has been proven that the average male in good physical condition may become incapacitated within minutes after entering cold water without protection/exposure equipment. Even with the use of exposure equipment, he will become severely hampered and lose mobile ability within a short time (10-15 minutes) in water that is 40°F or less.
Even throwing a line to a hypothermia victim may be useless because he might not be able to catch or reach or hold it. He might not even be able to make visual contact with the line or be able to acknowledge that it was thrown to him.
The cold affects not only the hands but also the facial muscles. This causes difficulty in speaking or blowing a whistle when we have to summon for help. Cold water in the ears can cause vertigo (dizziness) and nausea. Extreme hypothermia can lead to unconsciousness and death.
Luckily, most divers get back to safety and then complain of how bitterly cold they were. They never know that if something went wrong they never could have helped themselves or anyone else.
In addition to the diver, we should also show much concern for the safety of the tender. If the tender is affected by exposure and hypothermia, his much needed observation skills and performance level are all “going down.” He too must be monitored for action and reaction capabilities. A tender’s hands can be so cold he cannot pull in his diver.
At this point, you must be concerned not only with hypothermia and loss of body core temperature, but also with dehydration and body fluids. (This will be covered in an upcoming article.)
HYPOTHERMIA
A Lowering in Body Core Temperature
There are three types of HYPOTHERMIA:
- Acute hypothermia: occurs within 6 hours.
- Subacute hypothermia: occurs within 6-24 hours.
- Chronic hypothermia: occurs over a 24-48 hour period.
As in-water rescue personnel, we will be dealing mainly with acute hypothermia because falling into cold water is one of the fastest ways of losing body core temperature.
The normal body temperature of the human body is 98.6°F 37°C. The best method of recording this temperature is by a rectal thermometer. When this normal body temperature is reduced certain malfunctions occur within the body. A fractional drop in body temperature will cause shivering—a process where the body metabolism speeds up and starts to shiver to try and replace the heat loss. Should the body temperature continue to drop, the following detrimental effects will begin to occur:
The hypothermic victim is extremely fragile. The cold mycardium (muscle surrounding the heart) is extremely sensitive, and rough handling can cause the heart to go into lethal ventribular fibrillation. The cold heart—below 86°F 30°C—will not respond to drug administration or defibrillation. It is imperative that the heart is warmed sufficiently before continuing with the procedures discussed in this article.
Cold water diving can be fascinating, but you must be prepared. Here are some tips that will help you deal with exposure to the elements:
- Gear up accordingly, and remember to wear the hood, mitts/ gloves, and bootees.
- Be sure your equipment (suit, etc.) fits correctly, and practice.
- Abort the dive as soon as you begin to feel cold and uncomfortable or, at the worst, when you realize you are “bone cold.”
- Have proper protective clothing and exposure dress for tenders.
- Do not make a second dive until you are sufficiently rewarmed. Generally, this means that you have the ability to sweat. Except in an extreme emergency, if your body cannot sweat do not reenter the water.
When working in a cold environment (air temperature less than 20°F, water temperature less than 50°F), both divers and tenders should be cycled approximately every 12-15 minutes unless the diver and tender agree to shorten the dive even less. In a rescue mode this would necessitate having a second team that is ready to go. As the first team is coming out, the second team is entering the water.
- If you become hypothermic, get out of the water and change from your wet or dry suit into warm, dry clothes. Also get into a dry environment. Avoid hot coffee and tea. Never drink alcohol in this situation. Have hot soup, hot chocolate, etc.
- Rewarming a hypothermic victim is difficult at best, even when a prewarmed vehicle or building is available. The problem is compounded if you are on a boat.
The best rewarming procedure for any hypothermic victim (both minimally or severely exposed) is to use a unit called the Decupad TRC (Thermal Recovery Capsule). The TRC is a remarkable piece of equipment that can restore normal body temperature within minutes under conditions of minimal hypothermic exposure and minor body temperature loss. It also works with severe exposure cases, but takes longer to be effective. The victim or cold rescuer can be placed into the TRC while he is still wearing his wet clothing. The unit will whisk the damp water off and still reheat the body, beginning at the body’s core.
The Thermogel heat pad is also extremely useful in rewanning hypothermia patients. This reusable unit generates up to 140°F of heat and can be used up to 3,500 times. When exposed to the elements, it will last for 2-3 hours. When covered by a garment it can last as long as 5½ hours.
(For further information on these items, contact: Lifeguard Systems Inc., 25 West 43rd Street, New York, NY 10036.)
Remember, hypothermia decreases:
- Your body temperature,
- Your ability to perform,
- Your ability to react.
You can avoid becoming hypothermic by being aware of your environment.
It’s all going down. Don’t let it take YOU with it.»
