Fast Five Quiz: Frostbite and Hypothermia

Richard H. Sinert, DO


December 03, 2020

Mild hypothermia reflects a core temperature of 89.6°F-95°F (32°C-35°C). Between 93.2°F and 95°F (34°C-35°C), most people shiver vigorously, usually in all extremities. As the core temperature drops below 93.2°F (34°C), a patient may develop altered judgment, amnesia, and dysarthria. Respiratory rate may increase. At approximately 91.4°F (33°C), ataxia and apathy may be seen. Patients are generally stable hemodynamically and able to compensate for the symptoms. In this temperature range, the following may also be observed: hyperventilation, tachypnea, tachycardia, and cold diuresis as renal concentrating ability is compromised.

Moderate hypothermia reflects a core temperature of 82.4°F-89.6°F (28°C-32°C). Oxygen consumption decreases and the central nervous system depresses further; hypoventilation, hyporeflexia, decreased renal flow, and paradoxical undressing may be noted. Most patients with temperatures of 89.6°F (32°C) or lower present in stupor. As the core reaches temperatures of 87.8°F (31°C) or below, the body loses its ability to generate heat by shivering. At 86°F (30°C), patients develop a higher risk for arrhythmias. Atrial fibrillation and other atrial and ventricular rhythms become more likely. The pulse continues to slow progressively, and cardiac output is reduced. J wave may be seen on ECG in moderate hypothermia. Between 82.4°F and 86°F (28°C-30°C), pupils may become markedly dilated and minimally responsive to light, a condition that can mimic brain death.

Severe hypothermia reflects a core temperature below 82.4°F (28°C). At 82.4°F (28°C), the body becomes markedly susceptible to ventricular fibrillation and further depression of myocardial contractility. Below 80.6°F (27°C), most patients are comatose. Pulmonary edema, oliguria, coma, hypotension, rigidity, apnea, pulselessness, areflexia, unresponsiveness, fixed pupils, and decreased or absent activity on EEG are all seen.

Read more about the presentation of hypothermia.


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