【摘要】 目的 观察浅低温体外循环心脏直视手术围术期不同剂量异丙酚的脑保护效应。方法择期心内直视手术病人30例,随机分成三组,低剂量异丙酚组(3 mg·kg-·h-1),高剂量异丙酚组(6mg·kg-·h-1)及咪唑安定组(0.2 mg-kg-1·h-1,对照组)。于CPB开始前(A点),NPT降温稳定期(B点),复温至鼻咽温(NPT)36℃(C点),CPB结束后30 min(D点),CPB结束后4-6 h(E点),CPB结束后24 h(F点)同步采集桡动脉和颈内静脉血检测脑氧合、脑代谢状况和血浆丙二醛(MDA)浓度和超氧化物歧化酶(SOD)活性。结果低剂量异丙酚组有30％的病人在复温期出现脑氧合失衡,但能抑制自由基的产生和降低乳酸生成率(CLP)、脑乳酸氧指数(LOI);咪唑安定组可以较好改善脑氧合状况。对自由基、CLP和LOI无抑制作用;而高剂量异丙酚组可以改善脑氧合状况,抑制自由基的生成,降低CLP和LOI,但血压下降明显。结论浅低温体外循环心脏直视手术围术期高剂量异丙酚(6 mg·kg-1·h-1)可以改善脑氧合,抑制自由基生成,降低CLP及LOI,具有较好的脑保护效能。更多还原

【Abstract】 Objective To assess the cerebral protective effects of different doses of propofol during mild hypothermic cardiopulmonary bypass (32℃-35℃) .Methods Thirty consecutive ASA Ⅱ-Ⅲ patients aged 18-50 years, undergoing elective cardiac surgery under mild hypothermic CPB were randomly divided into 3 groups: in group Ⅰ and Ⅱ the patients were given a bolus of propofol 1 mg kg-1 at the beginning of CPB followed by propofol infusion at a rate of 3 mg · kg -1· h -1 (group Ⅰ ) or 6 mg· kg-1 ·h-1 (group D ) till the end of CPB and in group Ⅲthe patients received midazolam infusion at 0.2 mg· kg-1 h-1 instead of propofol. Anesthesia was induced with intravenous midazolam 0.15 mgkg-1 ,fentanyl 5 μg kg-1 and vecuronium 0.1 mg· kg-1 .After tracheal intubation fentanyl 30-50 μg kg-1 was infused during CPB and muscle relaxation was maintained with intermittent iv boluses of vecuronium. Surgery was performed with mild hypothermic CPB(32℃-35℃ ) .Arterial blood pH and PaCO2 were maintained within normal range and MAP was maintained at 50-80 mm Hg during CPB. Hematocrit was maintained at 25%-30% .Internal jugular vein(IJV) was cannulated and the catheter was advanced retrogradely till jugular bulb. Naso-pharyngeal temperature was monitored. Blood samples were taken simultaneously from artery and UV befor CPB (A) ,when mild hypothermia was being stably maintained(B) ,when the patients were rewarmed to 361 (C)and 30min(D),4-6 h(E)and 24 h(F) after discontinuation of CPB, for determination of cerebral oxygen metabolism and balance, cerebral lactate production (CLP), blood malondialdehyde (MDA) and superoxide dismutase (SOD) levels. CLP was calculated from arterial-cerebral venous blood lactate difference /arterial blood lactate concentration. Lactate oxygen index (LOI) was calculated from arterial-cerebral venous blood lactate difference /arterial-cerebral venous blood O2 content difference.Results In group I (low propofol dose) 30% patients developed cerebral O2 inbalance during rewarming but blood MDA, CLP and LOI were decreased. In midazolam group (group Ⅲ) cerebral O2 balance was improved but there was no depression of blood MDA, CLP and LOI. In groupⅡ (high propofol dose) cerebral oxygenation was improved and blood MDA level, CLP and LOI were significantly decreased.Conclusion The study shows that propofol infusion at a rate of 6 mg·kg-1· h-1 during CPB can improve cerebral oxygenaton, inhibit blood MDA level, CLP and LOI, and plays a role in the cerebral protection during cardiac surgery with CPB, but more vasoconstrictors are needed.更多还原