Application of pulsatile cardiopulmonary bypass for profound hypothermia in cardiac surgery.

Abstract

Profound hypothermia with core cooling has been considered unsafe as compared with surface cooling because of the induced metabolic acidosis. We carried out studies on mongrel dogs to determine whether or not conventional cardiopulmonary bypass with pulsatile blood flow for core cooling could replace the bypass with non-pulsatile flow. The recovery time from anoxic damage of the brain due to circulatory arrest was also studied. Cerebral excess lactate (ΔXL) (Huckabee) was determined throughout the course of hypothermia. During the cooling period from 30°C down to 20°C, the mean value of ΔXL in the pulsatile group was significantly lower than that in the non-pulsatile group (p < 0.01). After forty minutes of the first total arrest at 20°C, thirty minutes of pulsatile perfusion tended to eliminate the anaerobic metabolism of the brain caused by the first total circulatory arrest (p < 0.1). Thus, the anaerobic metabolism in the brain appears to be highly suppressed with pulsatile cardiopulmonary bypass during the cooling period. Correction of congenital heart disease in infancy can probably be more safely performed if pulsatile cardiopulmonary bypass for cooling and rewarming is employed instead of the non-pulsatile bypass.