深低温停循环前血气管理对脑代谢的影响

Effects of Different Blood Gas Management before Deep Hypothermia Circulatory Arrest

目的:观察深低温停循环前降温期不同的血气管理方法,对术中脑血流及脑氧糖代谢的影响,以寻求较好的脑保护方法。方法:12头幼猪建立体外循环,常温转流10min 后,按下述血气管理方法转流20min 降温至鼻咽温18℃:α-稳态方法(A组,n=6),pH-稳态方法(P 组,n=6)。经过60min 停循环,各组用α-稳态方法再灌注复温至鼻咽温36℃,于转流10min、降温末、再灌注5min 和复温末等4个时点测定脑血流量,动脉、静脉及颈内静脉血气和糖及乳酸含量,计算氧糖耗量,实验结束后计算脑含水量。结果:降温末 P 组脑血流量较 A组增加,P 组氧糖耗量较 A 组低:复温末两组脑血流量及糖氧化谢均未复正常;两组脑含水量无差异。结论:深低温停循环降温期应用 pH-稳态血气管理方法可以较好的抑制脑代谢,提供较好的脑保护。

Objective:In order to investigate the optimal method of cerebral protection,the effect of different blood gas management before circulatory arrest on cerebral blood flow and cerebral oxygen and glucose consumption during operation were studied,Methods:Twelve piglets were placed on cardiopulmonary bypass (37~C) for 10 minutes.All animals were cooled for 20 minutes with different blood gas management as follows until their nasopharyngeal temperatures (NPT) were 18~C: alpha-stat strategy (group A,n=6),pH-stat strategy (group P,n=6).Animals undergone 60 minutes of circulatory arrest were rewarmed with alpha-stat strategy till their NPT were 36~C. Measurement of cerebral blood flow (CBF),blood gas,blood glucose,and lactate content of systemic and internal jugular veins were made at the end of ten minutes normothermic perfusion at the end of cooling,at the beginning of reperfusion and at after rewarming.The brain water content was calculated at the end of the experiment.Results:CBF was decreased in the two groups during cooling, but CBF of group P was significantly more than group A at the end of cooling.At given temperature (18℃),cerebral oxygen and glucose consumption suppression was greater in group P.The CBF, cerebral blood gas (CMR O_2) and cerebral blood glucose (CMR gluc) were not recovered to normal levels at the end of rewarming.The differences of brain water content were insignificant. Conclusions:If pH-stat strategy is used dring the cooling before deep hypothermic circulatory arrest, it could provide better cerebral protection.