Effect of Hypothermia of 2 to 24 Hours on Oxygen Consumption and Cardiac Output in the Dog

Abstract

The changes occurring in cardiac output and oxygen consumption in short periods of hypothermia are the same when either ether or pentobarbital sodium is used as the anesthetic agent during the induction of hypothermia. Following an initial decrease in oxygen consumption, no further change occurred as long as the body temperature was maintained at a constant level. Cardiac output, arterial-venous oxygen difference, and coefficient of oxygen utilization remain unchanged for longer periods of time than most physiologic parameters studied during prolonged hypothermia at constant temperatures. After about 14 hours they also begin to alter so that by 24 hours the changes are profound. Stagnant anoxemia and marked increased in the coefficient of O2 utilization resulting from the markedly lowered cardiac output, which was 5% of the precooled controls, occurred.

Systemic Hypothermia in Treatment of Severe Brain Injury: A Review and Update

“…With continued cooling for 72 h, however, a severe coagulopathy develops, and animals die of multiorgan hemorrhage and congestion (Gray, 1957). Rats tolerate only 5-9 h of moderate hypothermia, dogs tolerate less than 24 h (at 20°C), and monkeys tolerate less than 48 h (Fisher et al, 1957;Steen et al, 1979Steen et al, , 1980. The potential complications of surface-induced hypothermia in man are cardiac arrhythmia and intracranial hemorrhage.…”