Effects of pulsatile perfusion on cerebral cortical blood flow after deep hypothermic circulatory arrest in dogs / 中华麻醉学杂志

ABSTRACT

Objective It was demonstrated that pulsatile perfusion (PP) is more physiologic and better than non-pulsatile perfusion (NPP) in maintaining blood circulation in vital organs. The purpose of this study was to determine the effect of PP on cerebral cortical blood flow(CCBF) after deep hypothermic circulatory arrest(DHCA) and the duration of safe DHCA. Methods Thirty-nine adult healthy mongrel dogs of either sex, weighing 10-15 kg were divided into two groups PP group (n = 18) and NPP group (n = 21) . The animals were anesthetized with intravenous pentobarbital 25mg?kg-1 . After tracheal intubation the animals were mechanically ventilated. Right femoral artery and vein were cannulated for intra-arterial pressure monitoring and infusion. The chest was opened and heart exposed. CPB was started after insertion of venous drainage catheter into right atrium and arterial cannula into ascending aorta. The bypass pump was shut off when the brain was cooled to 20℃. Circulatory arrest was maintained for 40 min, 60min or 80 min respectively. CCBF was measured during cooling and rewarming at 35℃, 30℃, 25℃and 20℃ by hydrogen clearance technique. Results During cooling CCBF gradually decreased and there was no difference in CCBF between the groups. After 40 min DHCA during rewarming CCBF increased significantly faster in PP group than in NPP group during the early period but CCBF returned to pre-cooling baseline level at the end of rewarming in both groups. After 60 min DHCA during rewarming when brain temperature returned to 30℃ and above , CCBF increased significantly faster in PP group than that in NPP group and returned to pre-cooling baseline level at the end of rewarming in both groups. Electron microscopic examination revealed that ultrastructure of neurons was normal after 40 min DHCA in both groups. After 60 min DHCA the ultrastructure was normal in PP group but swelling of neurons andedema of mitochondria could be seen in NPP group. After 80 min DHCA marked neuronal damages could be seen in both groups.Conclusions The results of our study suggest that PP improves CBF after DHCA and can protect brain from ischemic and hypoxic damages induced by DHCA and the duration of safe DHCA at 20℃ should be less than 60 min.