Hypothermia and Frostbite

ER series 4 – Hypothermia and frostbite

32~34.9°C	Mild	Tachypnea, tachycardia, ataxia, dysarthria, shivering
28~31.9°C	Moderate	Loss of shivering, dysrhythmia, muscle rigidity, dilated pupils, decrease level of consciousness, combative behavior, J waves on ECG
<28°C	Severe	Coma, hypotension, academia, ventricular fibrillation, asystole, flaccidity, apnea

J-waves are also known as Osborn waves. Picture from Wikipedia.

Investigations:

·      Bloods: ABG, CBC, electrolytes, serum glucose, creatinine/BUN, magnesium, calcium, amylase, coagulation profile

·      Imaging: CXR

·      Monitoring: ECG, rectal thermometer, urinary catheter, nasogastric tube

Predisposition factors include extreme age, drug overdose, alcohol ingestion, incapacitating trauma, cold water immersion, outdoor sports; investigations and treatment should kept with these factors in mind. Complications include ventricular fibrillation, asystole, volume and electrolyte depletion.

Treatment is based on rewarming and supporting cardiorespiratory function:

·      Do not do CPR if there is a pulse, even if a bradycardic one. Always take the pulse and rhythm over a full minutes.

·      If there is need for intubation, ventilate with warmed, humidified oxygen.

·      If in ventricular fibrillation and body temp <30°C, defibrillate up to maximum 3 times.

·      Gently replace fluids and electrolytes

·      Passive external rewarming—using insulating blankets and letting the body warm itself back up; suitable for patients with body temperature >32.2°C

·      Active external rewarming—using warming blanket; safer to use in conjunction with active core rewarming

·      Active core rewarming—using warmed humidified oxygen and IV fluids OR peritoneal dialysis with warmed fluids OR gastric/colonic/pleural irrigation with warm fluids. Suitable for patients with body temperature <32.2°C or those with cardiovascular instability

·      Beware of the afterdrop phenomenon—warming of extremities causes vasodilation and movement of cool pooled blood from extremities to core, resulting in a drop in core temperature and can lead to cardiac arrest.

When exposed to extreme elements, patients may not only present with hypothermia but also frost bite!

Frostbite—when ice crystals form between cells and as a result the cells die. Its symptoms and signs are much like that of burns, and the classification is also similarly based on the depth of injury.

Degree	Symptoms	Signs
1st	Initial paresthesia, pruritus	Erythema, edema, hyperemia, no blisters
2nd	Numbness	Clear blisters, erythema, edema
3rd	Pain, burning, throbbing, thawing (If too severe there can be lack of pain)	Hemorrhagic blisters, skin necrosis, edema, no movement

Management:

·      Treat underlying hypothermia as above

·      Remove wet and constrictive clothing

·      Immerse in agitated warm water 40~42°C for 10~30min. This can be very painful so administer adequate analgesia.

·      Clean injured area and leave open

·      Debride dead tissue if necessary

·      Tetanus and penicillin G as infection risk is high

·      Surgical consult if there are any eschars

·      Never allow thawed area to re-chill or freeze

This blog post is also available in podcast form! Search for us on iTunes and Googleplay or visit www.medonthego.podbean.com.