FACTORS AFFECTING SURVIVAL DURING PROLONGED HYPOTHERMIA.
Final rept., Feb 63-Apr 65,
BOSTON UNIV MASS HYPOTHERMIA LAB
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The mortality of anesthetized dogs maintained under prolonged hypothermia was studied and the factors responsible for death were evaluated. In the technically acceptable experiments, 45 of the dogs maintained at moderate hypothermic temperatures 26 plus or minus 1C died within 16 hours. The corresponding mortality in normothermic 38C control dogs was 7. Progressive hemoconcentration and bradycardia were observed during prolonged hypothermia. The former could be abolished by splenectomy. The use of artificial pacemakers to limit the effects of bradycardia was unsuccessful due to the development of other cardiovascular complications. Blood catecholamine levels increased with cooling to 33C but decreased below control levels at or below 25C however, prolonged hypothermia at 25C was associated with a progressive increase in blood catecholamines up to two to three times the initial control levels. The catecholamine content of aorta, kidney and spleen was not altered significantly by hypothermia, however, cardiac catecholamines decreased to below 50 of control with cooling to 25C. Adrenergic mechanisms apparently play a key role in the alterations of cardiovascular functions which limit survival during prolonged hypothermia. Author
- Medicine and Medical Research
- Escape, Rescue and Survival