Effects of pulsatile versus nonpulsatile flow on cerebral hemodynamics during pediatric cardiopulmonary bypass with deep hypothermic circulatory arrest

Cardiopulmonary bypass (CPB) with total circulatory arrest (TCA) adversely affects the neurologic outcome of pediatric patients after cardiac surgery. This study is designed to determine the effects of pulsatile versus nonpulsatile perfusion on regional and global cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO₂), cerebral oxygen delivery (CDO₂), and cerebral vascular resistance (CVR) before and after TCA in a neonatal piglet model. Twelve piglets were used in pulsatile (n = 6) and nonpulsatile (n = 6) groups. All piglets underwent 60 minutes of TCA and 45 minutes of rewarming. CBF, CMRO₂, CDO₂, and CVR were determined before TCA at a cerebral perfusion pressure (CPP) of 55 mmHg, and after TCA at CPP's of 55, 40, and 70 mmHg. Pulsatile flow increased regional and global CBF, CMRO₂, and CDO₂, and decreased CVR compared to nonpulsatile perfusion at all experimental stages. However, CBF, CMRO₂, CDO₂, and CVR diminished after TCA in both groups. These results suggest that the use of pulsatile flow improves cerebral recovery after TCA, and thus it may minimize brain injury compared to nonpulsatile flow in neonates and infants. Our results also confirm that TCA is the major cause for cerebral dysfunction during CPB.