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The incidence of admissions of patients with hypothermia was determined to examine whether hypothermia was more common in elderly patients with diabetes than in the general population after diabetic metabolic emergency cases had been excluded. A prospective survey of three accident and emergency departments identified 134 cases of hypothermia admitted from a catchment population of almost 157,000 aged 65 or over during the winters of 1981-2 to 1983-4. The predicted number of patients with diabetes in the population was nearly 5600 (3.5%). Twenty three admissions for hypothermia (17%) occurred in 20 patients with previously diagnosed diabetes. Women made up 87% of the diabetic admissions; the ratio of diabetic to non-diabetic admission rates in women was 7.9 (95% confidence interval 5.3 to 12.0). After excluding diabetic metabolic emergency admissions the ratio was 6.4. The ratio in men was 2.4, but the small number of admissions produced wide confidence intervals. Ten of the admissions with diabetes (43%) had pathological disorders that are associated with an increased risk of hypothermia. The frequency of these conditions is higher in patients with diabetes than in the general population and partly explains the increased risk of hypothermia in these patients.

Serial serum amylase and blood glucose levels were measured in 68 hypothermic (rectal temperature 35 degrees C or less) patients, including 15 who had hypothermic myxoedema (serum protein bound iodine 3.5 mug/100 ml or less). Raised amylase levels were found in 34 patients and probably reflected a mild acute pancreatitis. The high amylase levels correlated with low arterial PO(2) levels and significantly with high arterial PCO(2) levels and the base deficit but not with the severity or duration of the hypothermia. The acute pancreatitis does not explain why hypothermic patients with myxoedema have a poorer prognosis than those who are euthyroid. The pancreatitis occasionally contributed to the development, sometimes delayed, of diabetic ketoacidosis, blood glucose levels of over 120 mg/100 ml being found in 20 patients. There was a significant correlation between the raised serum amylase levels and the hyperglycaemia. Hypoglycaemia, sometimes profound, was found in 12 patients.

Accidental hypothermia has a high mortality and is associated with cardiac arrhythmias. To determine the incidence of arrhythmias and their importance 22 patients with accidental hypothermia (core temperature less than 35 degrees C) were studied by 12 lead electrocardiography and continuous recording of cardiac rhythm. Although 14 of the patients died (64%), only six died while hypothermic. Prolongation of the Q-T interval and the presence of J waves were related to the severity of the hypothermia. Supraventricular arrhythmias, including atrial fibrillation, were common (nine cases) and benign. Ventricular extrasystoles were also common (10 cases), but ventricular tachycardia or fibrillation did not occur during rewarming. In eight patients who died while being monitored the terminal rhythm was asystole. There was no correlation between the severity of hypothermia or the rate of rewarming and the clinical outcome. In the absence of malignant arrhythmias there is no indication for using prophylactic antiarrhythmic treatment in patients with accidental hypothermia. The presence or absence of severe underlying disease is the main determinant of prognosis.