胸段硬膜外阻滞复合七氟烷麻醉对兔缺氧性肺损伤时血流动力学和呼吸的影响

Effects of combined sevoflurane-epidural anesthesia on hemodynamics and respiration in rabbits with hypoxic lung injury

目的观察胸段硬膜外阻滞(TEA)复合七氟烷对兔缺氧性急性肺损伤(ALI)时血流动力学和呼吸的影响。方法健康新西兰大白兔28只,体重均>2kg。随机均分为对照组(C组)、缺氧组(H组)、七氟烷组(S组)和TEA复合七氟烷组(ES组)。ES组先行硬膜外置管后,首剂静脉注射1%利多卡因3mg/kg,此后每1h追加该剂量。各组麻醉后气管切开插管,机械通气,吸入质量分数为21%的氧气。30min后,H组、S组和ES组吸入氮氧混合气体,S组和ES组同时吸入七氟烷1最低肺泡有效浓度(MAC),直至动脉氧分压(PaO2)/吸入气体氧含量(FiO2)<300,ALI模型建立。3h后恢复自主呼吸,吸入21%的氧气,并于自主呼吸以及ALI模型建立后15min、30min、1h、2h、3h和恢复自主呼吸后测PaO2。C组始终吸入21%的氧气,并分别于相应时间点测PaO2。记录各组动物自主呼吸时和恢复自主呼吸后的心率(HR)、平均动脉压(MBP)、呼吸频率(RR)和潮气量(VT)。结果自主呼吸时,4组间HR、MBP、分钟通气量(MV)的差异均无统计学意义(P值均>0.05);H组、S组和ES组均于缺氧15min后建立ALI模型,急性缺氧导致HR和MBP降低。恢复自主呼吸后,H组、S组和ES组的MBP显著低于C组(P值均<0.05)。ES组在ALI模型建立后15min时的PaO2和恢复自主呼吸后的MV分别为(33.3±6.7)mmHg(1mmHg=0.133kPa)和(928.2±27.3)mL/min,显著高于S组的(25±3.3)mmHg和(339.5±27.3)mL/min(P值均<0.05)。结论兔缺氧性肺损伤时,TEA复合七氟烷不仅没有显著加重对血流动力学的干扰,而且可改善呼吸功能的恢复。

Objective To evaluate the effects of combined sevoflurane-epidural anesthesia on hemodynamics and respiration in rabbits with hypoxic acute lung injury （ALl）. Methods Twenty-eight New Zealand white rabbits of either sex, weighing above 2 kg were randomly divided into 4 groups （n =7 each） ： control group （C）, hypoxia group （H）, sevoflurane group （S） and combined sevoflurane-epidural anesthesia group（ES）. In Group ES, the catheter was inserted at T5 -T8 interspace and advanced 1 cm into the epidural space cephalad. Lidocaine （1%） was injected after the epidural block was confirmed by epidurography, followed by injection of the same dose at one hour interval. The rabbits were anesthetized with 30 mg/kg pentobarbital （iv）, tracheotomized, intubated and mechanically ventilated （ Group H, S and ES： FiO2 = 14%, Group C： FiO2 = 21%, VT = 10- 12 mL/kg, RR=25 bpm, I ： E= 1 ： 2） . The success of ALl model was defined at a PaO2/FiO2 value〈300. The rabbits in Group S and ES were also anesthetized with 1 MAC of sevoflurane. Three hours after ALl, all animals breathed spontaneously （FiO2 =21%）. Arterial blood gases were measured during spontaneous breathing （To, baseline）, at 15 rain, 30 rain,1 h, 2 h,3 h after ALl （1-5） ,and after resuming spontaneous breathing （T6） in group H, S and ES and at the corresponding time points in group C. HR, MBP,RR and VT were measured in all groups at To and T6. Results Parameters were similar among 4 groups during spontaneous breathing. ALl was induced at 15 minutes after hypoxia in Group H, S and ES and HR, MBP, PaO2 were significantly decreased in ALl rabbits （all P〈0.05 vs. group C）. PaO2 at T1 and MV at T6 in Group ES （ [33.3 ± 6.7] and [928.2 ± 27.3] mL/min, 1 mmHg = 0. 133 kPa） were significantly higher than those in Group S （ [25± 3.31 ] and [339.5± 27.31 mL/min, all P〈0. 05）. Conclusion Confined sevoflurane-epidural anesthesia can improve the respiratory function without negatively affecting hemodynamics in rabbits with hypoxic lung injury.