异氟烷对体外循环期间脑代谢及颈内静脉血中谷氨酸水平的影响

The influence of isoflurane on excitatory amino acid and cerebral oxygen supply consumption during cardiopulmonary bypass

目的 探讨体外循环（CPB）期吸入异氟烷对脑代谢及颈内静脉血谷氨酸的影响。方法选择28例择期心脏手术,随机分为两组。观察组17例,对照组11例。对照组采用全凭静脉麻醉,观察组在此基础上于CPB期间吸入1MAC异氟烷。分别于CPB前（A）、降温至鼻咽温33℃（B）、稳定的低温期（C）、复温至33℃（D）、CPB结束（E）、CPB结束后1h（F）共6个时点采取动脉血、颈内静脉血,行血气、血生化、血常规检查,并测定颈内静脉血谷氨酸（Glu）含量,并计算两组脑动静脉血氧含量差（CaO2-CjO2）。结果 观察组复温时（D点）脑CaO2-CjO2及颈内静脉血Glu含量明显低于对照组,观察组D点与B点值无显著差异（P>0.05）,对照组D点值明显高于B点值（P<0.05）。观察组D点GluG与CaO2呈曲线相关,当CaO2-CjO2在1.8～3.3ml/dl时,Glu值最低。结论 防止复温期脑氧供需失衡及抑制EAA的释放对CPB引起的脑损伤具有保护作用。

ve To investigate the effects of isoflurane on cerebral metabolism and excitatory amino acids in the jugular venous blood during cardiopulmonary bypass (CPB) . Methods Twenty-eight patients undergoing elective cardiac surgery were randomly divided into two groups: control group (C, n = 11) and isoflurane group (I, n = 17). All patients were premedicated with intramuscular pethidine 100 mg and scopolamine 0.3 mg. Anesthesia was induced with pentothal, fentanyl, vecuronium and succinylcholine. After tracheal intubation anesthesia was maintained with fentanyl, midazolam and pancuronium in group C, while in group I patients inhaled 1 MAC isoflurane during CPB in addition to the intravenous anesthetics and pancuronium. Radial artery was cannulated for intra-arterial pressure monitoring and blood sampling. Internal jugular vein was cannulated and the catheter was advanced cephalad until jugular bulb for blood sampling. Subclavian vein was cannulated for CVP measurement. ECG, T°(naso-pharyngeal and rectal), SpO2 and blood gases were monitored during operation. Arterial and jugular venous blood samples were taken before CPB (A), at 33℃(naso-pharyngeal T°(B), during stable hypothermia (C), rewarming to 33℃(naso-pharyngeal T°(D), at the end of CPB (E) and 1h after CPB (F) . Jugular venous blood glutamate (Glu) concentration was measured and the difference between arterial and jugular vein blood oxygen content (CaO2-CjO2) was calculated and compared between the two groups. Results In group I the CaO2-CjO2 and jugular vein Glu concentration at D during rewarming were not significantly different from those at B during cooling (P>0.05). But the CaO2-CjO2 and jugular vein Glu level at D in group I were significantly lower than those at D in group C. In group C CaO2-CjO2 and jugular vein glutamate level at D were significantly higher than those at B (P<0.05) . In both groups jugular vein Glu concentration was closely related with CaO2 -CjO2. Conclusions Isoflurane can protect brain by preventing cerebral oxygen supply and consumption imbalance and inhibition of excitatoryamino acid release.