TY - CHAP M1 - Book, Section TI - Hypothermia A1 - Zafren, Ken A1 - Thurman, R. Jason A1 - Jones, Ian D. A2 - Knoop, Kevin J. A2 - Stack, Lawrence B. A2 - Storrow, Alan B. A2 - Thurman, R. Jason PY - 2021 T2 - The Atlas of Emergency Medicine, 5e AB - Accidental hypothermia is an unintentional decline in core temperature below 35°C (95°F). Presentation may be obvious or subtle, especially in urban settings. Symptoms vary from vague complaints to altered levels of consciousness. Physical findings include progressive abnormalities of every organ system. Following initial tachycardia, there is progressive bradycardia (50% decrease in heart rate at 28°C [82.4°F]) with decline in blood pressure and cardiac output. Electrocardiogram (ECG) intervals are prolonged, beginning with the PR interval followed by the QRS interval and finally the QT interval. A J wave (Osborn wave; hypothermic “hump”) may be seen, but is neither pathognomonic nor prognostic. The J wave is present at the junction of the QRS complex and the ST segment. J waves may also be associated with central nervous system lesions, focal cardiac ischemia, young age, and sepsis. In mildly hypothermic patients, an invisible increase in preshivering muscle tone may obscure P waves. SN - PB - McGraw-Hill CY - New York, NY Y2 - 2024/03/28 UR - accessemergencymedicine.mhmedical.com/content.aspx?aid=1181050813 ER -