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Generalized immersion hypothermia aboard the rescue vessel
At environmental temperatures of less than 20-21 °C, man's survival depends upon insulation (body fat, clothing), the ratio of body surface to volume, the basal metabolic rate, and the will to survive.
Seawater freezes at -2°C. It may be assumed that most polar water with ice is as cold as this. In polar water, the body temperature falls very rapidly. Consciousness lasts 5-7 minutes, the ungloved hand is useless in 1-5 minutes, and death occurs in 10-20 minutes. It has been found that severe exposure of the head and neck to cold can cause massive cerebral haemorrhage. These parts of the body should be specially protected.
The rectal temperature should be taken in people rescued from cold water. This can help in estimating the chances of survival in each individual case.
When the rectal temperature is below 35 °C, hypothermia progressively lowers the basal metabolic rate, heart rate, and blood pressure and produces uncontrollable shivering. Hallucinations, apathy, and stupor or unconsciousness occur at 27-30 °C; and death from ventricular fibrillation or cardiac arrest at 21-28 ºC.
Treatment
The treatment of generalized (immersion) hypothermia begins with artificial respiration, using oxygen if available, Unheated oxygen should not be used for the hypothermia victim, because it will mean added cold; warm, moist oxygen should therefore be administered. An oral airway should be inserted. When respiration is absent or poor, or where there is no detectable carotid pulse, it may be difficult to tell if the patient is dead or alive. If there is uncertainty about the possibility' of life, always try artificial respiration and heart compression. When life-saving measures have been carried out, the patient's wet clothing should be removed and plans made for his immediate and rapid warming. If possible, immersion in a hot bath carefully maintained at 40-42 °C is desirable. If facilities are not available for maintaining a hot bath, hot-water bottles or heating-pads with layers of blankets can be used to warm patients. Great care is needed to avoid burns, to which the cold patient is especially vulnerable. Also, an airway must be maintained if the patient is unconscious.
It is recommended that heat be applied only to the central core of the body. It is of critical importance NOT to attempt to warm the victim's arms or legs since heating of the limbs causes cold blood to flow from them to the body core, causing further detrimental cooling of the core. Such incorrect treatment of hypothermia may induce a condition known as "after-drop".
The patient should be placed in the controlled temperature bath, or other methods of warming should be applied, until the rectal temperature is above 35 °C and he has stopped shivering.
Where there is a large number of cases, first treat those not breathing (but alive) and those who are unconscious. The continuous pouring of water heated to 40-42 °C over those waiting for treatment will increase the number of survivors.
The patient with hypothermia must be observed closely. Depression of breathing and cough reflexes may occur, and secretions may be retained. If a suction unit is available, catheter suction of the airway should be carried out frequently to remove secretions.
Nothing should be given by mouth because the patient may inhale liquid into the lungs, or he may vomit owing to a lack of bowel motility. Alcoholic drinks should not be given until 24 hours after recovery.
It may be necessary to administer intravenous fluids, but this should be done only after getting RADIO MEDICAL ADVICE. If breathing becomes shallow or slow, mouth-to-mouth artificial respiration should be given to support the patient's respiration. In the unconscious patient with hypothermia, the pulse and blood pressure should be checked every 15 minutes and the rectal temperature every half hour. If the patient is comatose or appears to be in shock, RADIO MEDICAL ADVICE should be obtained.
When the patient has been conscious for approximately 12-24 hours, 500 mg of tetracycline hydrochloride should be given by mouth every 6 hours for the next 5 days.
Plans should be made to evacuate the patient from the vessel to the nearest medical facility as soon as possible.