Simultaneous Observations of Changes in Metabolic and Circulatory Parameters during Hypothermia

Abstract

Simultaneous observations were made of changes in metabolic and circulatory parameters of the total body, heart and brain under hypothermia. Linear decreases were seen in cardiac output, coronary and cerebral blood flows during hypothermia until the body temperature fell to 30°C, and the rate of each decrease was almost the same. However, our data obtained at body tem-perature of 25°C showed that the decrease in cardiac output was prominent, compared with that in cerebral and coronary blood flows. That is, the rate of distribution of the blood volume in the coronary and cerebral circulations predominated over that of cardiac output.
This finding suggests that both the brain and heart muscle require relatively large quantities of oxygen even under the condition of hypothermia, and all metabolic and circulatory parameters change in a direction to maintain blood supply to the brain and heart muscle during hypothermia.