What is a characteristic finding in patients with hypothermia on an ECG?

In patients experiencing hypothermia, a hallmark manifestation on an electrocardiogram (ECG) is the presence of Osborn J waves, also known as "J waves." These deflections appear as abnormal upward notches that occur at the junction of the QRS complex and the ST segment. The appearance of J waves is a consequence of the heart's response to the lowered metabolic rate and altered electrophysiological properties associated with hypothermia.

J waves are most commonly seen in cases where the body temperature falls below a critical threshold, often around 30 degrees Celsius (86 degrees Fahrenheit). The mechanisms behind the J wave formation involve increased myocardial excitability and altered conduction velocity in the myocardium due to cooling, which can affect the repolarization process. Recognizing these waves on an ECG can be crucial for diagnosing and appropriately managing patients with hypothermia.

It's important to know that other findings, such as a prolonged QT interval, tachycardia, or atrial fibrillation, can occur in various cardiac conditions and are not specifically tied to hypothermia. The presence of Osborn J waves remains a distinctive and significant ECG marker for this particular state, emphasizing the body's physiological adaptations to low temperature.