The wide range of estimates can be explained by the fact that death cannot confidently be attributed to accidental hypothermia postmortem because most dead persons are cold. If data from Great Britain are extrapolated to the U.S. population, nearly 50,000 elderly Americans may be hospitalized each winter with occult hypothermia. Etiology and Pathogenesis Elderly persons with borderline hypothermia have age-related autonomic defects producing low peripheral resting blood flow, a nonconstrictive vasomotor response to cold, and easily provoked orthostatic hypotension. These defects are exacerbated by phenothiazines and correlate with hypothermia risk. Besides inadequate environmental heating in the winter, contributory factors include diminished perception of cold and poor heat conservation mechanisms.
Accidental hypothermia develops over many hours to several days.
Symptoms and Signs Patients are at high risk for death and for a clinical syndrome mimicking stroke or metabolic derangement. Hallucinations, combativeness, and resistance to aid may occur. Hypothermic patients have hands, feet, and abdomen that are cold to the touch. Shivering is strikingly absent, respirations are shallow and infrequent, slow pulse and low BP with atrial and ventricular arrhythmias are common, and the face may be puffy and pink. More commonly, ECG shows baseline oscillation produced by a fine rapid muscle tremor that is often mistaken for electrical interference or voluntary motion.