Abstract. Objective: To determine the effects of body temperature, ethanol use, electrolyte status, and acid-base status on the electrocardiograms (ECGs) of hypothermic patients. Methods: Prospective, two-year, observational study of patients presenting to an urban ED with temperature Յ95ЊF (Յ35ЊC). All patients had at least one ECG obtained. Electrocardiograms were interpreted by a cardiologist blinded to the patient's temperature. J-point elevations known as Osborn waves were defined as present if they were at least 1 mm in height in two consecutive complexes. Results: 100 ECGs were obtained in 43 patients. Presenting temperatures ranged between 74ЊF and 95ЊF (23.3ЊC-35ЊC). Initial rhythms included normal sinus (n = 34), atrial fibrillation (n = 8), and junctional (n = 1). Osborn waves were present in 37 of 43 initial ECGs. Of the six initial ECGs that did not have Osborn waves present, all were obtained in patients whose temperatures were Ն90ЊF (Ն32.2ЊC). For the entire group, the Osborn wave was significantly larger as temperature decreased (p = 0.0001, r = Ϫ0.441). The correlation between temperature and size of the Osborn wave was strongest in six patients with four or more ECGs (range r = Ϫ0.644 to r = Ϫ0.956, p = 0.001). No correlation could be demonstrated between the height of the Osborn waves and the serum electrolytes, including sodium, chloride, potassium, bicarbonate, BUN, creatinine, glucose, anion gap, and blood ethanol levels. Conclusions: The presence and size of the Osborn waves in hypothermic patients appear to be a function of temperature. The magnitude of the Osborn waves is inversely correlated with the temperature. Key words: hypothermia, electrocardiograph; Osborn waves. AC-ADEMIC EMERGENCY MEDICINE 1999; 6:1121-1126 T HE EFFECTS of hypothermia on cardiac conduction were first described in 1892.1 Since then, observations of the physiologic changes that occur with cooling of the heart have been reported in animals 2-14 and in humans undergoing craniotomy for subarachnoid hemorrhage, 15 surgery for cardiac anomalies, [16][17][18][19] and anti-cancer therapy.
20,21The first observation of the changes in the electrocardiogram (ECG) in a patient with unintentional hypothermia was reported in 1938. 22 In the following study, the changes in the ECGs of patients with unintentional hypothermia presenting to a large urban hospital ED are described, and the relationship of these changes to common laboratory parameters are analyzed. A review of the literature focuses on the development of the understanding of the effects of cold on the electrical conduction system of the heart and the resultant physiologic and ECG alterations.
METHODSStudy Design. This was a prospective, two-year observational study of hypothermia patients presenting to an urban ED. The study was approved by the institutional review boards of New York University School of Medicine, Bellevue Hospital, and the New York City Health and Hospital Corporation.Study Setting and Population. For the purposes of this study, patients were sele...
