Hypothermia Prevention, Recognition and Treatment.
Articles, Protocols and Research on Life-saving skills.

The recommended treatment of hypothermia in the field is core rewarming to prevent post-rescue collapse.

HYPOTHERMIA RESCUE RESPONSE

RESCUE, EXAMINE, STABILIZE, INSULATE AND TRANSPORT.

Over the past several years Search and Rescue (SAR) personnel have become increasingly skilled at managing accidental hypothermia. Coast guard, EMT's and aircrews have succeeded in treating and transporting an increasing number of patients suffering from this type of cold-injury. This article presents a brief summary of hypothermia and recommendations for handling cold patients.

Hypothermia is simply a lowering of the body's normal temperature. Significant hypothermia begins at body temperatures below 95 degrees Fahrenheit, 35 degrees Celsius, and severe hypothermia occurs at temperatures below 90°F/32°C. All body functions are slowed in severe hypothermia, including heart rate, breathing rate, metabolism and mental activity. A victim of severe hypothermia may display a variety of different signs and symptoms.

SAR personnel can both observe and measure the most important of these:

a. Pulse (slow to none);

b. Breathing (slow to none);

c. Mental status (slurred speech, unresponsiveness to pain or verbal stimulus, staggering walk or unconsciousness);

d. Cold skin; and

e. Low rectal temperature.

Severely hypothermic patients may have other problems that are not easily detected by rescuers, but which may affect the patient's survival.

These include:

a. Changes in blood chemistry;

b. Changes in oxygen and carbon dioxide content of the blood;

c. Irregular heart beats;

d. Dehydration;

e. Differences in temperature between deep body tissues and superficial body tissues.

The primary goals for SAR personnel in the treatment and handling of hypothermic patients are (1) to keep the patient alive, (2) keep the patient from getting any colder and (3) transporting the patient to a site of complete medical care.

1. RESCUING THE PATIENT.

Keep the patient in as horizontal a position as possible. This will help prevent shock and make it easier for the patient's heart to maintain blood flow to the brain. This position is particularly important for patients taken from the water. The pressure of surrounding water on the patient's body acts, in a small way, like anti-shock trousers. When the patient is taken from the water, this pressure is removed (as though suddenly deflating anti-shock trousers), and the patient's blood pressure may drastically fall. If patients cannot be rescued in a horizontal position (e.g. as in a rescue basket), they must be so placed as quickly as possible once aboard the vessel or aircraft.

2. EXAMINING PATIENT.

a. Remember ABC's (Airway, Breathing, Circulation); make sure the patient has an open airway, is breathing and has a pulse. If there is a high probability that the patient is severely hypothermic, breathing and pulse may be slow, shallow and very hard to detect. Therefore, take a full minute or more to measure these vital signs. Hypothermia patients with any measurable pulse or respiration obviously do not require Cardio-pulmonary Resuscitation (CPR). However if both pulse and respiration are absent, commence CPR. If the patient is found face-down in the water, assume a case of cold-water near-drowning. In this event commence CPR immediately.

b. Note mental status; evaluate the patient's level of consciousness, size of pupils, ability to respond if conscious, ability to walk if ambulatory and ability to think clearly. Where any of these characteristics are abnormal, suspect possible severe hypothermia.

c. Examine the patient for other possible injuries. Look especially for frostbite, soft tissues injuries, fractures, etc. Remember that when affected by hypothermia, the patient's ability to feel and respond to pain are depressed. Therefore a very careful search for these other injuries is necessary.

d. Check vital signs; measure pulse, breathing rate, blood pressure and TEMPERATURE. Core temperature measurements are essential (e.g. Tympanic). If tympanic temperature cannot be obtained, take a rectal or oral temperature. These other sites are not as accurate as the tympanic temperature, but at least you will know the patient is no colder than the temperature recorded in these sites (both of which are almost always lower than tympanic temperature).In all temperature recordings, low reading thermometers (down to 70°F/21°C) are essential (infrared thermometer). Are these provided in all your EMT kits?. Ordinary household thermometers are not good enough, since they go down to only 94°F/34°C. Glass thermometers are also unsuitable since hypothermic patients can thrash about, causing possible breakage and consequently, injury.

3. TREATING LIFE-THREATENING EMERGENCIES.

a. Commence CPR, if necessary; mouth to mouth or mouth to mask breathing during CPR is best because either provides warm, humidified air to the patient.

However, every effort needs to be made to use an apparatus which can ventilate the patient with 100% heated, humidified air or oxygen.

b. Avoid Advanced Cardiac Life Support (ACLS); normal defibrillation and drug treatments are not useful in treating severe hypothermia, since the cold heart will not respond as expected. Worse the heart can be damaged by repeated defibrillatory shocks. If administered, drugs will not be metabolized or cleared normally by the patient's liver and kidneys. Instead, they will accumulate in the body and become active as it warms.

c. Control bleeding in the usual manner.

d. Control shock; evaluate the patient carefully, especially before using anti-shock trousers. Inflation of the trousers may expose the heart to a sudden rush of cold, acidotic, venous blood isolated in the legs. Sudden temperature and/or pH changes in the heart have been suspected of causing cardiac arrest in severely hypothermic patients. Anti-shock trousers should only be used if the patient's low blood pressure is due to blood loss or severe fluid depletion. Moving a hypothermic patient's extremities may also cause cold peripheral blood to be pumped into the central circulation, affecting cardiac rhythm.

Gentle handling is critical !

 4. FURTHER MANAGEMENT

 a. Handle the patient very gently to avoid cardiac arrest.

b. INSULATE from further heat loss; this is one of the primary goals for rescuers in treating severe hypothermia. Do not expose the patient's skin to cold air, wind or spray, especially the down-wash created by helicopter rotor blades. If patients need helicopter transportation, GENTLY wrap them in blankets, sleeping bags, etc., and also be sure to insulate their heads.

c. Add heat; the intent is not to rewarm the patient, but rather to stabilize the core temperature and prevent further heat loss. Useful methods of heat addition are, in order of importance:

i) Deliver heated, humidified oxygen or air by mask at a temperature of 110°F/45°C. This treatment will prevent further respiratory heat loss which is significant in hypothermia and will help to stabilize heart, lung and brain temperatures.

ii) Apply external heat (hot packs, heating pads, etc.) to the head, neck, trunk and groin, but only in conjunction with inhalation therapy, defending the core temperature. These sources of external heat MUST be insulated from direct contact with the patient's skin, in order to prevent thermal burns. Hypothermic skin is very sensitive to heat and is easily burned.

iii) Provide rescuer's body heat. When wrapped together in a blanket or sleeping bag, a rescuer can donate body heat to a hypothermic patient. This technique is not without risk however, since slow external rewarming in this way may aggravate the frequency of abnormal heart beats. It should only be used when there will be a long delay in transporting the patient to a site of complete medical care.

IN NO CASE SHOULD HOT SHOWERS OR BATHS BE USED
WHEN THE PATIENT'S CHANGES OF BLOOD CHEMISTRY CANNOT BE MONITORED AND BALANCED.

d. Postpone orally administered treatment; give nothing by mouth until the patient is considered sufficiently conscious to both cough and swallow (i.e. fully conscious). Hot drinks are not effective in warming a severely hypothermic victim. They may be useful, however, in raising the morale of mildly hypothermic victims.

NEVER ADMINISTER ALCOHOL !

e. Administer intravenous (IV) fluids: if a blood vessel can be found, despite vaso constriction, administer already warmed to body temperature 5% dextrose in water or 5% dextrose in normal saline. Do not use Ringer's lactate because the hypothermic liver may not be able to metabolize the lactate normally.

Most hypothermic patients are dehydrated, administer 300-500 cc's of dextrose in water or saline rapidly, followed by 75-100 cc/hr. DO NOT ADMINISTER COLD I.V. FLUIDS. Use an I.V. warmer or carry a plastic I.V. bottle inside a rescuers clothing (preferably next to the skin) to keep the fluids warm.

f. Transport to a medical facility as soon as possible.

Published by Robert Douwens with permission from the author,

CDR. DR A.M. Steinman, USPHS. U.S. Coast Guard ON SCENE Magazine.