Temperature Related Conditions LtCol Svein Torp, Norwegian Armed Forces Medical Services In this article we describe issues of importance to the medic in the management of heat-related conditions, cold-injuries and burns.

Physiology1 Our body temperature is maintained at 37 degrees at all times by a centre in our brain. To maintain a constant temperature the body must ensure that energy production increases when heat loss increases. The energy we use at rest is known as the basal metabolic rate. Our metabolic rate can be increased above this basal level thereby increasing heat production. Our body gains heat by: Physical activity Food intake. Our body looses heat by: Radiation (invisible heat waves that can be seen by IR-techniques) Conduction (e.g. holding a cold object) Convection (currents of air against the skin) Evaporation (sweating). Our body regulates heat loss by: Varying blood circulation to the skin (pale, cold, red, warm) Varying sweat production.

Shivering Shivering is a bodily function in response to cold temperatures and hypothermia.

When our core temperature falls, the shivering reflex is triggered. This reflex is

regulated in a centre of our brain known as the hypothalamus. Shivering

increases the rate of heat production by 2-5 times. Muscle groups begin to shake

in small movements expanding energy in an attempt to create warmth. If you

start to shiver, make sure to put on dry clothes and seek shelter in a warm place.

Shivering will also increase our energy demands, you should therefore ensure to

eat sufficiently. Note that shivering may also be a sign of fever without any

significant cold exposure.

Cold Injuries Hypothermia2-10 If heat loss is greater than heat production, the body temperature will fall (hypothermia). In this chapter the word temperature refers to our core temperature. This is measured in the rectum; alternatively in the esophagus or ear drum. Hypothermia is usually divided into the following stages:

Mild hypothermia. Core temperature is between 33-35 degrees. Symptoms include feeling cold, teeth chattering, shallow rapid breathing, somewhat increased pulse, cold hands, feet and skin and increased urine production (cold diuresis). Our ability to think clearly and take sensible actions is preserved.

Moderate hypothermia. Core temperature is between 30-33 degrees. Decrease in shivering, muscle weakness, difficulty walking, respiration and pulse slows down. Our ability to think and take sensible actions is impaired, sometimes resulting in strange behavior such as undressing (paradoxical undressing). Most people are unable to get out of the situation by themselves, and need help from others to survive.

Serious hypothermia. Core temperature is below 30 degrees. The condition further deteriorates. Muscles and joints become stiff making it hard to move. Pulse and respiration slows down even more and consciousness is impaired. At 27-28 degrees the patient may become unconscious. The pupils dilate and may not react to light. A hypothermic person at this stage may be misinterpreted as being dead.

Symptoms and signs Symptoms and signs vary depending on how low the body temperature is. Note that a slow pulse in a hypothermic patient is not only slow but also weak! Further, a slow respiration is not just slow in frequency (number per minute), but also shallow. It may be difficult to examine/find circulation and respiration in a hypothermic patient, even though it is present.

First aid The goal of the rescuer is to prevent a further fall in body temperature and avoid complications. Further loss of temperature is prevented by getting the patient into an area sheltered from the weather and wind. Put warm covers around the patient. Remove wet clothes if dry clothing is available. Wet clothes can also be covered with plastic to reduce heat loss (evaporation). Hypothermic patients may get complications. This includes suffocation secondary to an obstructed airway. Other complications include circulatory disturbances with a fall in blood pressure or disturbances of the heart rhythm. Actions to prevent such complications include: Place the patient in the recovery position Handle the patient very carefully. All movements and positional changes

should be done very slowly. The patient should not be moved around more than absolutely necessary.

If the patient goes into cardiac arrest CPR should be initiated following the usual guidelines. Remember that low temperature protects the brain. Patients may wake up without brain damage; even after several hours of CPR. HOWEVER, remember that a slow unassisted circulation is better than an artificial CPR circulation. Other measures to consider include: Giving oxygen and monitoring the heart rhythm. Hypothermic patients who are awake/conscious: Can be given hot drinks Can be heated in the field or during transportation. Hypothermic patients with clearly reduced consciousness, or who are unconscious, should not be given anything to drink and be taken immediately to hospital.

Frostbite3,6,11-13 Local tissue temperature in exposed areas may fall even though the core temperature is normal. Water within and around our cells will freeze to ice if the tissue temperature falls below zero degrees A local frostbite will then occur.

Superficial frostbite The skin becomes white and sensation is reduced. The skin may still be moved in relation to deeper tissues. Treatment: Immediately start by rewarming skin to skin (i.e. put your frostbitten fingers under your armpit). Avoid further cold exposure!

Deep frostbite The skin is white in appearance and sensation is lost. The skin is severely frozen and CAN NOT be moved in relation to deeper tissues. Treatment: Cover the area and wrap it with dressings and/or cloths. Rewarming is usually a hospital task at this stage. Prevent hypothermia and further exacerbation of the condition. Protect the frozen skin against pressure and trauma. In an emergency situation, a deep frostbite can be rewarmed in the field. Rapid rewarming in hot water using a bathtub with a temperature of 40-42 degrees is preferable. This is very painful, and the limb is very vulnerable after rewarming. Blisters, swelling, ulcers and pain will appear. The limb must be protected as much as possible and further cold exposure avoided. Do not use artificial heat for rewarming local frostbites. The skin lacks sensation and will not register high temperatures. Following frostbite the skin is damaged and less resilient (to heat, pressure or trauma). There is a connection between our core temperature and the likelihood of local frostbite. A low core temperature reduces blood circulation to the skin (where heat is lost). Reduced circulation to the skin increases the risk of frostbite. Areas at special risk for local frost bite include: Fingers Toes Nose, cheek, chin and ears.

Local frost damage should first and foremost be prevented: Look for white spots on yourself and your friends (buddy-buddy control).

Immersion foot13,14 Immersion foot is also known as Trench foot. The condition is caused by prolonged exposure to damp and cold. Tissue temperature never falls below zero degrees. As such, ice crystals do not form and the term Non-freezing cold injury is sometimes used. Immersion foot can in special cases develop within 6-8 hours, but usually takes longer time (over 2 days). The condition can also affect the hands. Symptoms and signs: Cold, wet and with time numb feet. Pale and poorly circulated skin(slow capillary refill). Pain and swelling may appear on reheating, and the skin becomes red/purple in color. First aid: Do not rub or massage the area. The feet should be elevated, dried and warmed carefully. It may be necessary to give strong pain killers. Patients with swelling and pain should be transported on a stretcher. Patients are at risk of chronic pain and discomfort. Prevention: Do not walk around with wet and cold feet. Change socks frequently, especially in wet and cold surroundings.

Avalanche accidents15,16 The primary life threatening occurrence in an avalanche accident is not hypothermia. Most victims of an avalanche die of suffocation, usually within thirty minutes. Only 1/10 dies after 30 minutes has passed, and then usually as a consequence of hypothermia and high carbon dioxide content of inspired air. The recommended plan of action sets a limit at 45 minutes when treating avalanche victims. This includes a margin of safety. We therefore make a distinction if more or less time than 45 minutes have passed since the avalanche.

Less than 45 minutes Finding and helping the injured is most important. Look for signs or indications of where the injured is located. If the patient can be dug up within ten to fifteen minutes, there is a high likelihood of survival. After this time the prognosis will be worse. If the patient does not breathe you should start CPR until other health workers arrive to take over. If the patient is breathing, continue your examination drill (CDE).

More than 45 minutes Call for help. Snow contains enough oxygen to survive over some time. The problem is carbon dioxide which collects in front of the face of the injured leading to suffocation with time. If the patient does not breathe initiate CPR until other

health workers take over. If the patient is breathing, continue your examination drill (CDE). Keep in mind that respiration and pulse are difficult to find in hypothermic patients. All activity with and around the patient should cease while looking for evidence of respiration and circulation. You may have to use as much as one minute on this assessment. If the patient has signs of respiration and circulation continue therapy as described for hypothermia.

Snow blindness17 Snow blindness, also known as Welder's eye, are superficial wounds on the cornea after exposure to radiating ultraviolet (UV) light. Exposure of unprotected eyes to sunlight reflecting from the snow is a common cause. Similar damage may be caused by sunlight reflecting from white sand, ice or water. Symptoms may include a foreign body sensation, irritation, redness and watering of the eyes. Patients may also suffer reduced vision (visual acuity). Symptoms and signs typically appear within 6-12 hours of exposure to strong sunlight or other forms of UV-radiation. Snow blindness does not usually cause permanent vision loss. Wearing sunglasses that offer 100% UV protection and low transmittance is recommended as part of prevention. If you suspect snow blindness flush the eyes for several minutes with sterile water (saline). Apply a dressing covering the eye. This should be left in place for 24 hours, it is preferable if the patient is seen by medical personnel. They will administer topical antibiotic drops or ointment, because of the severely painful nature of this condition pain killer and anti-inflammatory medications are often given.

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Temperature Related ConditionsShivering

Cold Injuries Mild hypothermia. Core temperature is between 33-35 degrees. Symptoms include feeling cold, teeth chattering, shallow rapid breathing, somewhat increased pulse, cold hands, feet and skin and increased urine production (cold diuresis). Our ability to think clearly and take sensible actions is preserved. Moderate hypothermia. Core temperature is between 30-33 degrees. Decrease in shivering, muscle weakness, difficulty walking, respiration and pulse slows down. Our ability to think and take sensible actions is impaired, sometimes resulting in strange behavior such as undressing (paradoxical undressing). Most people are unable to get out of the situation by themselves, and need help from others to survive. Serious hypothermia. Core temperature is below 30 degrees. The condition further deteriorates. Muscles and joints become stiff making it hard to move. Pulse and respiration slows down even more and consciousness is impaired. At 27-28 degrees the patient may become unconscious. The pupils dilate and may not react to light. A hypothermic person at this stage may be misinterpreted as being dead.Symptoms and signsFirst aidFrostbite3,6,11-13Superficial frostbiteDeep frostbite

Immersion foot13,14Avalanche accidents15,16Less than 45 minutesMore than 45 minutes

Snow blindness17

REFERENCES