Circulatory Arrest during Hypothermia in Cardiac Surgery: An E.E.G. Study in Children

Abstract

During the course of open heart surgery a deliberate arrest of the circulation at lowered body temperature was performed as part of the routine surgical procedure. In 23 children E.E.G. studies were carried out throughout the operation and particular attention was paid to the changes occurring immediately after complete cerebral ischaemia at various body tem temperatures. Mild hypothermia (32-28° C.) had been induced in 15 cases (group 1) and moderate hypothermia (24.3-18.5° C.) in a further eight cases (group 2). In each case the occlusion of the circulation was followed by E.E.G. changes and finally by complete disappearance of all phasic activity. The time interval between circulatory arrest and E.E.G. equipotentiality was much greater in the children of group 2 with moderate hypothermia (average time 109 seconds) than in those of group 1 with mild hypothermia (average time 35 seconds). The length of time between circulatory occlusion and the flattening of the E.E.G. traces probably represents a measure of the rate of cerebral utilization of available metabolites from the stagnating blood. Within the age group studied (3 to 14 years) there was no evidence that total cerebral ischaemia, at comparable temperatures, could have a different effect on the brain of the younger than of the older children. © 1966, British Medical Journal Publishing Group. All rights reserved.