HYPOTHERMIA and its application to surgery is a subject of much current interest both in the laboratory and in the operating room. Reduction of body temperature to low levels still has considerable risk, and ventricular fibrillation and cardiac standstill constitute the most serious complications. The present study was designed to determine what changes occur in the acid-base balance of the blood during cooling and to see whether alterations in the acid-base balance might influence the cardiac complications and mortality rate. If a pH change occurred during cooling, could it be controlled by the respiratory rate, by the concentration of gases inhaled, or by the administration of base or acid?
It is well known that when blood is cooled in vitro it becomes more alkaline.* There is, however, little information available about the acid-base changes of the blood in vivo when the body temperature is reduced. In hibernating animals there is