The Quick and Dirty Guide to Hypothermia
The sun has set on a great summer as we prepare for another cold winter ahead. In our profession, that means more than just digging up our long johns and gloves. Use this time of year to brush up on your cold weather treatments and protocols. They will surely be necessary in the next few months.
Always be prepared for the unexpected, it will give you the advantage when it matters.
What is Hypothermia?
Hypothermia is a medical emergency that occurs when your body loses heat faster than it can produce heat, causing a dangerously low body temperature. Normal body temperature is around 98.6 F (37 C). Hypothermia occurs as the body temperature falls below 95 F (35 C). When the body temperature drops, the heart, nervous system and other organs starts deciding who gets to stay alive. Organ systems are shut down by the body to keep the core of the body alive as long as possible. Untreated, hypothermia will eventually lead to complete failure of the heart and respiratory system leading to, what? You guessed it, cardiac arrest and death.
Hypothermia is most often caused by exposure to cold weather or immersion in a cold body of water for a period of time causing the core temperature to drop rapidly. It can also be caused by grandma falling in the kitchen floor and laying there all night. There are 4 main sources of heat loss from the body:
Conduction: Loss of heat via direct contact with cool objects - Grandma lying on the bathroom floor all night, even in a warm house.
Convection: Loss of heat via air or water currents - Exposure to cold water or cold wind.
Evaporation : Loss of heat via sweating - Moisture dries on the skin and removes heat.
Radiation: Normal loss of heat via the environment - primarily exposure to the head and neck
Signs and Symptoms:
Use mental status as your primary diagnostic to quickly determine how serious the hypothermia has become. Check the blood glucose; shivering causes glucose to be used up quickly. Checking a pulse is a lot harder in hypothermic patients due to peripheral vasoconstriction, so take at least 30 seconds to a minute to feel for a pulse. Paradoxical undressing occurs when the hypothalamus is no longer working correctly and the patient removes his clothes because he actually feels warm. Here is a chart showing the degrees of hypothermia and the symptoms with which they are commonly associated.
|98-95||37-35||Cold Pale skin
The patient is alert, shivering
|Poor muscle coordination.
Rapid breathing Rapid heart rate.
|95-90||35-32||Cold, waxy skin.
Puffy face, possibly pink.
Slow heart rate.
Stupor or coma.
Slow breathing rate.
Slow heart rate
|86-82||30-28||Fixed dilated pupils.
Slow or rapid heart rate.
V-fib, Possible cardiac arrest.
Fixed, dilated pupils.
|Barely detectable vital signs.
In hypothermic patients, focus on:
Preventing further heat loss by removing them from cold environment and remove wet clothing
Rewarming the body core with blankets, heat packs in the armpits and on the groin and abdomen, and warm IV fluids
Avoiding malignant cardiac rhythms such as ventricular fibrillation by moving the patient as little as possible
Pro Treatment Tips:
- Transcutaneous pacing is ineffective for hypothermia related bradycardia - Rewarm first.
- Atropine is ineffective in treating hypothermia related bradycardia - Rewarm first.
- Lidocaine is ineffective at preventing hypothermia related ventricular dysrhythmias.
- Intravenous thiamine and glucose is often recommended as many causes of hypothermia are complicated by Wernicke's encephalopathy.
- Use IV fluid warmer or heating pad set on low to warm IV fluids for infusion.
- Defibrilation is unlikely to convert V-fib in hypothermic patients. Do CPR and continue to warm the patient to be more successful.
- When your patient is found to be in a shockable rhythm, delivery of one initial biphasic shock @ 200 joules, it is believed that any further shock delivery will actually damage the hypothermic heart muscle. Continuing CPR combined with a safe expedited transport to the nearest medical facility is your patients’ best chance at survival. There are anecdotal reports of sudden cardiac death when trying to intubate hypothermic patients, but no evidence exists to this effort, so follow your airway protocol as normal.
Take Hypothermia by Water Immersion Very Seriously
Pulses are harder to detect in hypothermia because the body is shutting down blood flow outside the core. Take up to 1 minute when feeling for a pulse.
Medications may be ineffective. Treatment primarily involves removing the patient from the cold environment, and initiating rewarming techniques.
Patients are never dead until they are warm and dead. Don't stop working.
Suggested related reading from Medictests.com
The Quick and Dirty Guide to Memorizing the NREMT Medical Assessment
The Quick And Dirty Guide to Difficulty Breathing
The Quick And Dirty Guide to Cardiology II: Coronary Circulation
Other links for further study
Hypothermia - Our Treatment is Our Prevention
This has been the Quick and Dirty guide to Hypothermia. You can now return to digging through sheets at the hospital, trying to find one without snot, shit or blood stains.
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