全麻单肺通气过程中硬膜外阻滞对肺内分流和氧合的影响

The effect of epidural on arterial oxygenation and intrapulmonary shunt during long term one-lung ventilation with general anesthesia

目的 通过观察在全麻开胸单肺通气 (OLV) 2小时后 ,给予胸段硬膜外 0 .5 %罗哌卡因阻滞时肺内分流率、动脉氧合及血流动力学的变化 ,了解硬膜外麻醉对单肺通气过程中肺内分流和氧合的影响。方法 2 0例ASAI～II择期需单肺通气开胸行食管癌根治手术的病人 ,均以静脉异丙酚维持麻醉 ,单肺通气 12 0分钟后随机分为 :静脉丙泊酚 (异丙酚 )组和静脉异丙酚加硬膜外组。连续监测平均动脉压、平均肺动脉压、中心静脉压、心输出量、心电图、脉搏氧饱和度等。调整异丙酚输注速度使脑电双频指数维持在 44～ 5 5。两组分别于清醒状态 (Base)、OLV60、12 0分钟 ,OLV13 5、15 0、180分钟 (即硬膜外给药后 15、3 0、60分钟 )及恢复双肺通气 3 0分钟 (Da3 0分钟 )时测定动脉及混合静脉血血气 ,计算肺内分流率 (Qs/Qt)。结果 GPE组硬膜外给药后与给药前相比肺内分流率差异无显著性 (P >0 .0 5 )。GPE组动脉氧分压 (PaO2 )在硬膜外给药后 3 0分钟 ( 2 3 9± 60mmHg)及 60分钟 ( 2 75± 45mmHg)高于给药前OLV12 0分钟 ( 170± 75mmHg) (P <0 .0 5 )。两组间各时间点分流率、PaO2 及循环指标差异无显著性 (P >0 .0 5 )。结论 单肺通气过程中给予硬膜外阻滞不会增加肺内分流率和降低PaO2 。

Objective To investigate the effect of epidural on oxygenation and shunt fraction after long term(2h) one-lung ventilation(OLV) with general anesthesia techniques. Methods 20 patients underwent prolonged periods of OLV for elective thoracic surgeries were randomly allocated to one of two groups, propofol/vecuronium/ fentanyl anesthesia group(GP,n=10) and propofol/vecuronium/ epidural ropivacaine anesthesia group (GPE,n=10). Bispectral index was maintained in the range of 45-55 by adjusting propofol infusion rate. Arterial and pulmonary blood gases were analyzed before induction,OLV60,120min,OLV135,150,180min(after epidural block 15,30,60min) and 30min after resuming two-lung ventilation (TLV) in all patients, respectively. Venous admixture percentage (Qs/Qt),arterial and mixture venous oxygen content were measured. MAP, MPAP, CVP, HR and CI at each time point were recorded. Results Qs/Qt was no significantly difference before and after epidural block with 0.5% ropivacaine in GPE group.PaO 2 was significantly increased after epidural block 30min and 60min with 0.5% ropivacaine in GPE group. For Qs/Qt ,PaO 2 and PvO 2 in all patients, there were no significantly difference between groups. Conclusion Thoracic epidural ropivacaine 0.5% dose not affect Qs/Qt and decrease PaO 2 after long term(2h) one-lung ventilation with general anesthesia.