Hypothermia

- by Fernanda Morley R.N. C.C.R.N Email

THE DEADLY EFFECTS OF COLD

The sun is shining and the air has an "October wind" nip to it. Your vessel is gliding through the waves. It is a perfect day for a sail...until someone on your vessel falls overboard. Then it can become a nightmare, depending on your skill to handle this situation. Your ability to conduct a good "man overboard" rescue and the effects of the sea will determine the outcome. Hypothermia can occur quickly after immersion in water, or more insidiously at any time of year, especially on long passages. It can occur even while snorkeling in the warm Caribbean waters! Your ability to assess and treat the various stages of hypothermia is extremely necessary and important. WHAT IS HYPOTHERMIA? + it is a lowering of the body's core temperature caused by heat loss and the body's inability to keep the internal temperature constant. The body responds to this drop to protect our precious vital organs: heart, lungs and brain. + 37 degrees Celsius ( 98.6 degrees Fahrenheit) is the normal core temperature. The body can self compensate only for small upward and downward variations. Impending hypothermia can occur at 36 degrees Celsius!

HOW TO PREVENT HYPOTHERMIA 

To prevent it we must understand how heat is lost from the body. Convection: A thin layer of heated air exists next to the body. Air movement decreases this heat. Conduction: Heat moves from one source to another. Water cools the body 10 times faster than air. Wet clothes and immersion in water causes the rapid conduction of heat away from the body. Evaporation: Water changes into vapour. Sweat will dry on the skin and results in cooling. Radiation: Heat is radiated from the sun or other heat sources such as a stove. We lose most of our heat this way Wind Chill: Wind moves warmed air away from the body causing rapid cooling.

These are the MAIN HEAT LOSS AREAS: 
+ groin...the large blood vessels are close to the surface 
+ chest sides...there is little muscle or fat to insulate 
+ head and neck...over 50% of heat loss occurs here

PREVENTATIVE METHODS

1) Clothing 
+ cover exposed body surfaces such as head, hands and feet 
+ close openings around head and neck 
+ dress in layers including proper thermal underwear. Wear clothes that breathe. Use a wind and waterproof shell for outside cover. 
+ cover the mouth and nose with a knitted wool scarf and full hat. 
+ wear wool and synthetics such as polypropylene. Down is useless when it wet. 
+ replace damp clothes, especially wet socks 
+ if you are limited with extra clothing, place the damp wool clothing over the dry. This will help keep an insulated layer. 

2) Seek and create shelter from the cold, wind and rain. A dodger and bimini are good shelters. 

3) Assess your watch intervals according to the weather 

4) use a pad to insulate your body and a cold surface 

5) FOOD 
+ nibble on high energy food such as candy, nuts, granola bars 
+ sip warm water. Do not use alcohol or caffeine as beverages in cool conditions 

6) Wear a safety harness...stay out of the water! 

7) Wear a PFD...especially at night 

8) Practice "Man Overboard" drills on a regular frequency and when new crew have come onboard. 

9) Know the early signs and symptoms of hypothermia...and make sure that all crew monitor each other. Remember that the greatest threat of hypothermia happens on rainy, windy, days with temperatures between 40 and 60 degrees! 

STAGES OF HYPOTHERMIA

Early...core temperature 36 degrees Celsius. 
+ skin pale, numb and waxy + fatigue begins 
+ weakness + muscle tenseness. Shivering may begin 
+ judgment capability is still intact

Treatment 
+ remove from the elements 
+ give hot drinks 
+ halt further heat loss with extra clothing

Mild...core temperature 35 to 34 degrees Celsius 
+ uncontrolled intense shivering occurs 
+ movements become less coordinated. Unable to grasp a line or ladder at this point. 
+ judgment capability impaired, but is still alert 
+ feelings of intense coldness such as numbness in hands and feet

Treatment + remove from elements if able 
+ remove wet clothing...handle the person gently as jolting can affect heart function by pumping back cold blood to the heart. 
+ avoid massaging the muscles as this will also send cold blood back to the heart. It will result in further core temperature drops or heart standstill. 
+ layer on clothing. Cover the head and neck well! 
+ apply lukewarm objects such as chemical packs, water bottles or hand warmers to the head, neck and trunk. Watch for signs of burns. The temperature of these objects should be tested on your elbow before application. 
+ if person is able to swallow and is conscious, give warm, non alcoholic drinks such as milk or soup. Avoid coffee, tea and cocoa as these are cardiac stimulants. Avoid alcohol as it dilates blood vessels causing further heat loss. So much for the Saint Bernard dog and the rum barrel wrapped around his neck!

Moderate...core temperature 33 to 31 degrees Celsius 
+ shivering slows or stops. The body's initial compensating response to cold is to shiver uncontrollably. This generates heat by the involuntary muscular movement. When this fails, the body stops shivering because it uses up more energy...hence heat to cause the muscle to shiver. It is a sign the person is in serious trouble! 
+ muscles begin to stiffen 
+ speech is slow, vague, slurred 
+ mental confusion and apathy is present 
+ drowsiness and strange behaviour occurs 
+ breathing is slower and more shallow

Treatment 
+ As above ...with mild stage 
+ monitor vital signs and be ready to start CPR. If there is a pulse and breathing....no matter how faint...do not give CPR. Keep a VERY CLOSE watch! 
+ skin to skin such as person to person contact is imperative. Once the person has stopped to shivering, they are unable to get warm again without an external heat source.

Severe... core temperature less than 31 degrees Celsius 
+ skin cold and bluish + eyes may be dilated 
+ marked lack of coordination 
+ may show signs of clouded consciousness or may become unconscious. 
+ person may appear DEAD, especially with cold waxy skin and dilated pupils. NEVER assume a person is dead until the body has been rewarmed.

Treatment 
+ Skin to skin contact in areas of chest and neck. Keep head covered. A prewarmed sleeping bag with one or two naked people in it is very functional. 
+ exhale warm air near the person's nose and mouth or introduce warm steam into the area. 
+ use mild heat... stop any further temperature loss. 
+ if the person is semi conscious, keep the person awake. He/she is in serious trouble and needs close and continuous monitoring. HANDLE VERY GENTLY! By now the heart is extremely sensitive. Again, DO NOT MASSAGE THE MUSCLES. REWARM SLOWLY! 
+ if the person is unconscious check the carotid pulses. Take a full two minutes and check each side if unable to palpate initially on one side. Check the breathing. If no pulse or breathing is present , then start CPR. Always assume that this person's situation is reversible. DO NOT GIVE UP! The person is considered to be in a "metabolic ice box"! Continue CPR until the person has been rewarmed and the heart begins to beat, or the person applying CPR cannot continue without endangering themselves, or the person has been rewarmed and the heart does not begin to beat. 
+ medical help is imperative...hospitalization is needed

CONCLUSION 

+ Treatment should be approached with knowledge and care. More damage than good can be the outcome with the wrong treatment. 
+ PREVENTION. The best way to treat hypothermia is to PREVENT IT! 
+ Always remember gentle handling, insulation, no alcohol, coffee, tea, cocoa and gradual rewarming. 
+ Any method which will rewarm the person in a hurry will likely cause further complications or death 
+ If it is difficult to distinguish the level of hypothermia through visible signs and symptoms...then assume severe hypothermia. Usually, if shivering has stopped, it indicates a more severe situation. 

Here's to happy and WARM sailing! 

Fernanda Morley R.N. C.C.R.N. Morley Yachting Services

Web site

See also: You Are Your Own 911 and Sleep Deprivation by this author.
Other site: http://www.cbc.ca/news/background/health/hypothermia.html