Acute accidental hypothermia
This is most commonly due to immersion in cold water. Falling into water colder than 5°C (41°F) is a grave emergency with almost immediate effects. The victim gasps, shivers violently * curls up, inhales water, and is dead from drowning in about five to fifteen minutes. It is doubtful whether even onlookers experienced in the first aid of drowning can act quickly enough. If the subject is wearing plenty of clothing which retards the loss of body heat, a life-jacket that keeps the head out of the water, has face protection to prevent cold water from splashing on it (which stops the breathing, slows or stops the heart, and predisposes to drowning), and has been well enough trained to know to keep perfectly still in the water, he or she has well-established average chances of survival from the immersion. These expectations are about fifty minutes in freezing water; around three hours in water at 10°C (50°F), some six hours at 15°C (59°F), and very many more hours at 20°C (70°F) and above.
Other factors that influence the onset of hypothermia in water are increasing age; lack of fitness; liability to panic; lack of recent food intake for internal heat production; and the recent drinking of alcohol, which without food causes a severe fall in blood sugar, with immediate confusion and clumsiness.
Any insulating material will protect against hypothermia. The protective influence of fat under the skin as an insulant against heat loss in the water led Professor Keatinge of the London Hospital to bring an old adage up to date by suggesting that, instead of ‘women and children first’, it should read ‘thin boys and men first’, and then ‘plump girls and women’.
If the casualty is known to have collapsed in the water after some five to fifteen minutes’ immersion, then drowning is the
most likely explanation. If he or she is conscious, can talk only clumsily, or is incoherent and cannot answer questions, then hypothermia is the diagnosis.
Do not constrict the chest with any harness or allow the victim to make any movement, especially climbing nets to board a ship or to clamber into a small boat—there have been many surprising deaths after the rescue that are now thought to be due to sudden stress on a heart already grievously affected by the cold.
Ideally, the patient should be placed in the horizontal position, with the head slightly down, protected from further heat loss and taken immediately to a facility for rapid rewarming. Try to ascertain if water has been inhaled in however small a quantity because hospital investigation is then urgent. In the meantime commence rapid re-warming in a bath (showers are not of any use) in which the water is kept at 42°C or as hot as the bare elbow can tolerate.
If the rectal temperature is being monitored during this treatment, it will be found that it continues to fall for the first fifteen minutes or so—the notorious ‘after-drop’, the significance of which is not yet completely understood. Resuscitation facilities should ideally be available—collapse may occur at any time until the patient is out of danger. If rapid (bath) re-warming is not available the victim must be allowed to ‘come round’ from his or her own internal heat production in a bed with duvet, ‘space
Wind chill index. (Modified from Adam, J.M. (1969). Community Health 1, 39-46.)
The Wind Chill Index is indicated by the point at which the air temperature (vertical axis) and wind velocity (horizontal axis) cross; record it at hourly intervals to monitor deteriorating conditions.
Zone A No danger. Zone B Little danger when wearing light clothing provided meals are regular and overexertion avoided. Beware of a sudden deterioration in the weather. Zone C Requires full clothing protection, waterproof shelter, hot food and drink, prevention of overexertion. In the UK, most deaths from hypothermia occur in this zone. Zone D Travel becomes dangerous on overcast days—sudden rain, sleet, hail, or snow can be hazardous. Zone E Temporary shelter is dangerous to live in, travel should be contemplated only in heated vehicles. Zone F Exposed flesh starts to freeze. Zone G Exposed flesh freezes in less than one minute, and survival efforts are required.
blanket’, or light blanket insulation only. The supply of external heat by electric lamp cradles, electric blankets, and the like requires a hospital environment, with intravenous fluids, oxygen, and injectable drug supplies ready to hand.
Chronic accidental hypothermia
This is defined here as being much longer in its onset than the foregoing, (which may require 20-30 minutes only, if the water is cold enough). The very young and the elderly are generally the most susceptible to hypothermia, but the accent here is on the middle age groups engaged in exploring, biological surveys and observations, hill-walking, mountaineering, or stranded in a cold and hostile environment. Commonest in the cold/wet climate, it is usually the product of soaked garments and a wind chill factor in zone C or above. It is often complicated by overexertion, especially in those who are unprepared for sudden weather changes, who become lost and also have no reserve food or clothing, tent or sleeping bag. Mist, rain, sleet, hail, snow, and white-out may occur suddenly, and absence of map and compass, torch and whistle help to compound the situation.
Early recognition of the condition is of the greatest importance, and this requires one or more companions in a group (beware the lone ranger) who know each other well and can adopt the ‘buddy system’ to watch one another. Warning signs include complaints of feeling cold, tired, or listless; inability to keep the pace, progressing to stumbling and then repeated falls; unexpected, unreasonable, or uncharacteristic behavior with unusual aggression; and failure to understand or respond to repeated questions or commands.
Uncontrollable bouts of shivering, which then cease, and disturbances of vision herald collapse and unconsciousness with dilated pupils. The victim’s pulse at wrist or neck will be irregular. In the unlikely event that temperature measurement has been possible, it will have been about 35°C (95°F) at the start of the above list of signs and symptoms, and about 32°C (90°F) by the time the shivering is diminishing. The risk to life is now increasing and death may occur suddenly below 28°C (82°F), with disturbance of the heart rhythm and eventually cardiac arrest. The sooner the following action starts, the better the outcome:
- Protect from wind, rain, etc. by rigging a tent, poncho, or other bivouac or shelter, laying the victim in the ‘head-down’ position if he is conscious, or the coma position if not, on a groundsheet, ‘space blanket’, or in a large polythene bag.
- Insulate him, having stripped the wet clothing if possible, with a sleeping bag(s) covering head and face as well.
- Re-warm him if unconscious by the body warmth of a companion—stripped and in bed beside him. If conscious, a quick ‘brew-up’ of hot sugary tea followed later by hot food will hasten recovery.
- Observe for the cessation of breathing or pulse when mouth-to-mouth resuscitation and/or external cardiac massage must start.
- Send two people for help, but first, give them tea and food in case they too are affected by the cold conditions.
- Treat the patient as a stretcher case, no matter what may be said to the contrary. If he is injured, of course, there will be no argument, and transport must be organized.
Local severe chilling of exposed or poorly insulated tissues— nose, cheeks, chin, ears, hands, and feet—can occasion freezing with or without the general chilling of hypothermia. The time required for the ‘frost’ to ‘bite’ depends on how cold it is, the degree of wind chill and the amount of tissue at risk. The last comprises either the area of skin exposed or a tissue to which the blood supply has been restricted (i.e. by tight boots and matted socks where feet or toes are concerned). One patient of mine was a young soldier driving a Euclid earth-mover in winter-time Korea. His engine broke down as night was falling, so he curled up in the cab and fell asleep. The temperature dropped during the night, and the blood supply to his right foot was sufficiently impeded by his awkward posture to cause frostbite and eventual loss of the foot.
The initial warning of impending frostbite is intense pain in the part at risk, and at this stage, the part must be re-warmed. The victim, however, may not be aware of the pain—from intense preoccupation, exhaustion, having suffered an injury, or from profound lethargy—and it eventually disappears. The part
becomes numb, white and hard to the touch because it is frostbitten. ‘Buddies’ watch each other’s faces for this.
Prevention of frostbite consists of being aware of the risk, keeping an eye on the wind chill index and discussing the conditions with local inhabitants, and wearing adequate protective clothing.
Treatment At the painful stage of impending frostbite, the treatment follows the sequence set out above stop, protect, insulate and re-warm the part. Cover nose, cheeks, or ears until the shelter is erected and warm; hands and fingers are slipped under the clothes to the opposite armpit or between the thighs. Feet require the heroic test of friendship through the clothing on to the belly of a companion! Pain will disappear and normal color and sensation will indicate when danger is over. Take the opportunity to correct any other factors that may predispose to frostbite by changing wet clothing, producing a hot meal, or reminding one’s companions of other dangers such as the touching of bare metal with bare hands this can cause instantaneous freezing, as can slopping petrol on to bare skin.
Established frostbite is a serious problem, particularly when k involves fingers and hands, or feet and toes, when lasting damage may affect the victim’s earning capacity in later life. A speedy but gentle journey to hospital is essential. Once frostbitten tissue has thawed, up to 3 month’s of skilled medical attention may be necessary; moreover, if tissue once thawed is even slightly chilled again, it is liable to much more extensive damage. In an emergency involving a frozen foot (the worst) far from any hospital, there are three options:
- If the journey must be completed and no patient transport is available, remember that it is possible to walk on a frozen foot, though most certainly not on one that has thawed. Ideally, hot food and drink are necessary, together with correction of any clothing defects. Give a pain-killer such as two tablets of paracetamol, with an oral antibiotic such as a penicillin or tetracycline in capsule or tablet form, dosage 250 mg every five to six hours day and night to combat any infection.
- If a stretcher with men to carry it, or alternatively a man or dog-drawn sled is available, treat the victim in the warm shelter as above, not omitting the pain-killers and antibiotics. Remove the boot and sock as carefully as possible, cover the foot lightly with gauze, pad it with cotton wool, and wrap it up loosely. Make him or her comfortable and warm and immobilize the foot gently before setting off.
- If the patient is at a static base with medical advice available and the possibility of eventual evacuation, then the patient should stay put. Keep him or her in a room, where a high temperature can be maintained (about 21°C or 70°F). Elevate the part on a pillow with sterile precautions if available. Expose the foot to the warm air, wash it gently with an antiseptic solution such as warm 1 percent cetrimide, dab it dry, inspect carefully and report the findings by radio for medical advice. This is likely to include the administration of a course of antibiotics and painkillers as above.
If the fingers and/or hand are frostbitten, clean the skin area with the cetrimide solution and dab dry very gently. Separate the fingers with cotton wool after winding a sterile bandage around each, and place a thick sterile pad in the palm of the hand so that the fingers are in a ‘glass-holding’ position. Bandage the whole lightly and elevate the forearm in a sling. Commence a course of antibiotics and pain-killers as already outlined. Reassurance and gentle treatment are of the essence until the patient arrives at the hospital.
Never rub frostbite with snow or anything else, because the delicate tissues will suffer more damage.
Immersion foot occurs when the lower limbs and feet have been kept in cold conditions for hours or days, as happened in the trenches of World War I and in the lifeboats after the shipwreck during World War II. After the first sensation of cold passes off, the feet feel numb, and this continues for the long period of immobility and restriction of blood that is a prerequisite of the disorder. The patient may be unable to walk, or walks with difficulty, complaining that it feels like walking on cotton wool. Inadequate food, general chilling, lack of sleep, and exhaustion complete the typical picture.
On examination, the skin is blotchy-white, the ankles are swollen and marked deeply with pressure ridges from boots, etc. As the patient becomes warm, and the affected area is dried gently,
the feet become hot, red and more swollen, and there is intense pain. The victim must be taken to the hospital, and if this is likely to take time, should be treated with pain-killers and antibiotics as for frostbite. The legs must be elevated, protected from further damage and exposed in a warm room. Blisters may form on the feet in the first two days or so, and must be kept scrupulously (but gently) clean. It may be many months before an established case is able to return to work.
Chilblains are the mildest form of cold injury and are due to alternate exposure to wet/cold conditions and rapid re-warming. The disorder occurs frequently in the UK, where 50 percent of the inhabitants are said to have suffered from it at one time or another. Prevention is by keeping the extremities warm, heating the house, eradicating draughts, and avoiding long periods of standing without moving.
Clothing for cold conditions
Clothing should be well fitting and built upon the ‘layer’ principle from the innermost air-trapping layers to the outermost windproof and/or waterproof coverings. Each layer must be larger than the one beneath it to prevent constrictions and to preserve the insulating air. Neck and wrist openings are recommended as they permit ventilation by ‘bellows action’ so that water vapor from sweat can escape when one is working hard. Thus the inner layers do not become wet with condensed sweat, whence chilling could occur. Layers, too, may need to be donned and doffed for that same reason, as the workload dictates. I do not favor polo-necked sweaters because they cannot be ventilated.
Special requirements include the protection of the head which, in still air at 0°C, can lose one-quarter of the entire body’s heat production per hour; and this rate increases with lower air temperatures and higher wind chill. The peculiar shape of the feet and ankles make their insulation a problem, and great care should be exercised in the selection and fitting of socks and boots. Socks that are worn for too long become a double hazard by becoming matted or developing holes so that they lose insulation value, and by shrinking so that the blood supply to the toes and feet is impeded. Ensure a good overlap of sleeves with the gloves or mittens, because a strip of frostbite on the inner side of the wrist is extremely painful.
Summary of advice for travelers Hot Climates
- Full acclimatization takes about 3 weeks.
- Thirst sensation is a poor guide to your true water requirements in a hot climate always drink more than you think you need.
- Salt requirements are also high you may need to consider adding salt to drinking water, as described on.
- Guidelines for preventing and treating heat stroke and heat exhaustion are given.
- No acclimatization is possible, so it is vital to be adequately prepared for cold conditions, with suitable clothing and equipment.
- Cold injuries and emergencies are described.