| ObjectivesVarious brain protective techniques were used to decrease the mortality and the incidence of neurological complications during aortic arch surgery, complex neonatal congenital heart surgery and the other complex cardiovascular sugery, in order to achieve good clinical outcome. Combination of ASCP and DHCA was suggested as the most popularly used method of cerebral protection during the aortic arch surgery and the other complex cardiovascular sugery. However, the oxygen management for this combination strategy is still controversial. The aim of this study was to investigate the effects of hyperoxia management during deep hypothermia in circulatroy arrest rabbit on the blood gas indexes, regional cerebral oxygen saturation, biochemical indexes, cerebral injury markers, morphology of brain tissue and the ratio of water to brain, to determine the cerebral protective effects of hyperoxia management, to get the experimental experience and basics for clinical application of hyperoxia management.MethodsA deep hypothermic circulatory arrest (DHCA) and antegrade selective cerebral perfusion (ASCP) rabbit model was established. Thirty-two11-13week-old male New Zealand rabbits (weighing2.6to3.4kg) were assigned to four groups with a random number table:a deep hypothermic circulatory arrest group (D group), an antegrade selective cerebral perfusion group (S group), a DHCA+hyperoxia management group (DH group) and an ASCP+hyperoxia management group (SH group). There were eight rabbits in each group. We recorded the intraoperative values of arterial oxygen pressure (PaO2), arterial oxygen saturation (SaO2), jugular venous oxygen pressure (PjvO2), jugular venous oxygen saturation (SjvO2), blood lactate level and continous regional cerebral tissue oxygen saturation (rSO2). The levels of neuron-specific enolase (NSE) and s100B proteins of the blood, the brain superoxide dismutase activity, malondialdehyde levels, lactic acid levels, glycogen levels and ratio of water to brain were measured after the operation. Light microscope and electron microscope were used for morphological examination of brain tissue specimens.ResultsBefore initiating circulatory arrest, levels of PaO2, PjvO2, and SjvO2in the SH group and DH group were significantly higher than those of the D and S groups. Before initiating reperfusion and five minutes after reperfusion (the time points related to circulatory arrest), levels of PaO2, PjvO2, and SjvO2in the SH group were significantly higher than those of the other three groups (p<0.05). In the duration of CA, rSO2in the SH group was significantly higher than that in the other three groups (p<0.05). The brain tissue of the animal in the SH group was with higher SOD activity, lower MDA level and lower lactic acid level than in the other group. There were lower s100B level and NSE level in the SH group than those in the other groups. Compared with the other three groups, the brain tissue of the animal in the SH group kept a better cell morphology of neuron including cell membrane, cellular organelle, cell nucleus.ConclusionsHyperoxia management during deep hypothermia provided substantial dissolved oxygen and better oxygen supply over normoxia management. Hyperoxia management for the combination of ASCP and DHCA could reduce the risk of cerebral injury, repay the oxygen debt quickly during the rewarming period, keep a good oxygen supply and demand balance. This study confirms that hyperoxia management for the combination of ASCP and DHCA provides a better cerebral protection over normoxia management in a rabbit model. |
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