Beneficial effect of balloon-induced pulsatility on brain oxygenation in hypothermic cardiopulmonary bypass

Background. Sufficient O₂ delivery to meet the demand is an important factor for protecting the brain during cardiopulmonary bypass (CPB). This study was designed to investigate the influences of temperature, pulsatility of blood flow (intra-aortic balloon pump-induced) and flow rate during CPB on the cerebral oxygenation. Methods. Patients were divided into five groups. Normothermia (36°C): pulsatile (n=8, 2.5 L/min/m²), non-pulsatile (n=12, 2.5 L), and nonpulsatile perfusion (n=12, 2.8 L); hypothermia (30°C): pulsatile (n=9, 2.5 L) and nonpulsatile perfusion (n=11, 2.5 L). The oxygen saturation (SjVO₂), lactate and CPK-BB levels in the jugular venous blood were measured. Results. In all of the normothermic groups, the SjVO₂ value decreased during the CPB (p<0.1-01). No remarkable change was observed in the hypothermic groups, with the exception during the rewarming period in the nonpulsatile group. A higher SjVO₂ and a lower frequency of SjVO₂ values <50% were observed in the hypothermic pulsatile group, as compared with those in the normothermic groups (p<0.05). The levels of CPK-BB were nearly the same, however the levels of lactate were higher in the normothermic pulsatile and nonpulsatile (2.5 L) groups (p<0.05). Conclusions. We concluded that the hypothermic CPB was advantageous over normothermic CPB in regard to the SjVO₂ levels and lactate production. The beneficial effect of intra-aortic balloon pump assist was only obtained in the hypothermic CPB.