Hypothermia in adults: A strategy for detection and Tx

Electrocardiography. An electrocardiogram is essential to evaluate for arrhythmias. Findings associated with hypothermia are prolongation of PR, QRS, and QT intervals; ST-segment elevation, T-wave inversion; and Osborn waves (J waves), which represent a positive deflection at the termination of the QRS complex with associated J-point elevation.⁸ Osborn waves generally present when the core body temperature is <32°C (89.6°F) and become larger as the core body temperature drops further.³

Differential diagnosis. Hypothermia is most commonly caused by environmental exposure, but the differential diagnosis is broad: many medical conditions, as well as drug and alcohol intoxication, can contribute to hypothermia (TABLE 3¹).

Treatment: Usually unnecessary, sometimes crucial

Most patients with mild hypothermia recover completely with little intervention. These patients should be evaluated for cognitive irregularities and observed in the ED before discharge.⁹ Moderate and severe hypothermia patients should be assessed using pre-hospital protocols and given cardiopulmonary resuscitation (CPR) for cardiac arrest. Pre-hospital providers should rely more on symptoms in guiding their treatment response because core body temperature measurements can be difficult to obtain, and the response to a drop in core body temperature varies from patient to patient.¹⁰

Early considerations: Airway, breathing, circulation (ABC)

A first responder might have difficulty palpating the pulse of a hypothermic patient if that patient’s cardiopulmonary effort is diminished.⁹ This inability to palpate a pulse should not delay treatment unless the patient presents with lethal injury; the scene is unsafe; the chest is too stiff for CPR; do-not-resuscitate status is present; or the patient was buried in an avalanche for ≥35 minutes and the airway is filled with snow (FIGURE^3,11,12). Pulse should be checked carefully for 60 seconds. If pulses are not present, CPR should be initiated.

Prevention of further heat loss should begin promptly for hypothermic patients who retain a perfusing rhythm.¹¹ Lifesaving interventions, such as airway management, vascular access for volume replenishment, and defibrillation for ventricular tachycardia or ventricular fibrillation should be carried out according to Advanced Cardiac Life Support protocols.¹¹ Patients in respiratory distress or incapable of protecting their airway because of altered mental status should undergo endotracheal intubation. Fluid resuscitation with isotonic crystalloid fluids, warmed to 40°C (104°F) to 42°C (~107°F) and delivered through 2 large-bore, peripheral intravenous (IV) needles, can be considered.

Special care should be taken when moving a hypothermic patient. Excessive movement can lead to stimulation of the irritable hypothermic heart and cause an arrhythmia.