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

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 20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120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44～55.两组分别于清醒状态(Base)、OLV60、120分钟,OLV135、150、180分钟(即硬膜外给药后15、30、60分钟)及恢复双肺通气30分钟(Da30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＞0.05).GPE组动脉氧分压(PaO2)在硬膜外给药后30分钟(239±60mmHg)及60分钟(275±45mmHg)高于给药前OLV120分钟(170±75mmHg)(P＜0.05).两组间各时间点分流率、PaO2及循环指标差异无显著性(P＞0.05).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.

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

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.