Effects of various deep hypothermic circulatory arrest approaches on cerebral oxygen metabolism

Objective To observe the effects of various deep hypothermic circulatory arrest approaches on cerebral oxygen metabolism and configuration. Methods Eighteen dogs were randomly divided into three groups:deep hypothermic circulatory arrest(DHCA)group, DHCA with retrograde cerebral perfusion(RCP)group, and DHCA with intermittent antegrade cerebral perfusion(IACP)group. The temperature of the dogs was cooled down to 18℃through cardiopulmonary bypass, then the circulation was arrested for 90 min. Before the circulatory arrest, 45 and 90 min after the circulatory arrest and 15 and 30 min after re-circulation, blood samples were obtained to detect PO2, SaO2, and SjvO2. The amount of CaO2 and CjvO2 and cerebral oxygen extraction rate(CERO2)was calculated. At the end of the procedure, hippocampus tissue was excised to be examined under a transmission electron microscope. Results After circulatory arrest, a marked increase in CERO2 and decrease in SjvO2 occurred in both DHCA and DHCA+RCP group and no obvious change in SjvO2 or CERO2 occurred in DHCA+IACP group. Conclusion An unbalanced oxygen supply in the cerebrum would occur due to the prolongation of DHCA. No enough oxygenated blood was transported to the cerebrum by RCP owing to the limitation of perfusion volume, resulting in the development of cerebral and neuronal edema. A better oxygen supply can be achieved by IACP.