THE EFFECT OF PULSATILE PERFUSION ON CEREBRAL BLOOD-FLOW DURING PROFOUND HYPOTHERMIA WITH TOTAL CIRCULATORY ARREST

In 39 mongrel dogs, regional cerebral blood flow was measured during p ulsatile and nonpulsatile deep hypothermic cardiopulmonary bypass with total circulatory arrest. Total circulatory arrest was performed at 2 0 degrees C cerebral temperature for 40 minutes in 15 dogs, 60 minutes in 12 dogs, and 80 minutes in 12 dogs. Cerebral blood flow in both gr oups decreased as cerebral temperature fell and there was no significa nt difference in cerebral blood flow between the two groups during the cooling period. After circulatory arrest for 40 minutes, as cerebral temperature increased to 35 degrees C, cerebral blood how in both grou ps recovered to values as high as the respective initial values, which were measured just after the beginning of cardiopulmonary bypass for cooling (102.5% +/- 10.2% in the pulsatile group and 97.2% +/- 12.6% i n the nonpulsatile group). After circulatory arrest for 60 minutes, ce rebral blood dow in the pulsatile group increased to 141.8% +/- 16.1% of its initial value when the cerebral temperature became 35 degrees C ,but it remained significantly lower (64.5% +/- 9.2%) in the nonpulsat ile group (p < 0.01). After circulatory arrest for 80 minutes, cerebra l blood flow in both groups remained lower than the respective initial values. These results suggest that pulsatile perfusion maintains cere bral blood flow even during profound hypothermia and that it may prote ct the brain from ischemic and hypoxic damage caused by profound hypot hermia and total circulatory arrest in cardiac operations.