ECG Diagnosis: Hypothermia

Abstract

Figure 1. 12-lead ECG from a man, age 38 years, with somnolence, altered mental status and core body temperature of 86°F (30°C) Demonstrates sinus bradycardia with a ventricular rate of 52 beats/minute, with Osborn (J) waves at the terminal junction of the QRS complexes, consistent with severe hypothermia. Figure 2. 12-lead ECG from same patient following rewarming to a core body temperature of 92°F (33.3°C) Demonstrates a normal sinus rhythm with a ventricular rate of 75 beats/minute, with resolution of the Osborn waves. An Osborn wave (also referred to as the J wave) is a characteristic ECG finding for hypothermia consisting of an extra deflection on the ECG at the terminal junction of the QRS complex and the beginning of the ST-segment takeoff. 1 Osborn waves usually occur when the core body temperature falls below 90°F (32°C), and are believed to result from an exaggerated outward potassium current leading to repolar-ization abnormality. 2 They can also be found in other conditions such as hypercalcemia. 3 Other ECG findings in patients with hypothermia can include prolongation of the PR, QRS and QT intervals, T wave inversions , and various dysrhythmias including atrial fibrillation, sinus bradycardia, atrioventricular block, and ventricular fibrillation. Fatal ventricular fibrillation or asystole can occur in hypothermic patients when core body temperature falls below 82.4°F (28°C). 1 v