不同压力持续气道正压对单肺通气时患者氧合作用和肺内分流量及内源性抗氧化酶变化的影响

Effects of continuous positive airway pressure at different levels on systemic oxygenation and intrapulmonary shunt and changes of endogenous antioxidant enzymes during one-lung ventilation

目的 探讨不同压力持续气道正压（CPAP）对单肺通气时患者氧合作用和肺内分流量（Qs/Qt）及内源性抗氧化酶变化的影响。方法 择期行食管癌根治术患者40例,ASAⅠ或Ⅱ级,随机均分为五组,全程采取双肺通气（TLV组）、在单肺通气时非通气侧肺的支气管导管直接开放于大气（OLV-0组）、在非通气侧肺连接CPAP系统,分别给予CPAP 3cm H2O（OLV-3组）,6cm H2O（OLV-6组）和9cm H2O（OLV-9组）。于平卧位开胸前（T0）、侧卧位单肺通气后（TLV组于开胸后15min,T1）、30min（T2）、60min（T3）、90min（T4）、120min（T5）、150min（T6）及手术结束时（T7）,分别采取动脉血行血气分析并计算Qs/Qt,抽取静脉血测定血清内源性抗氧化酶：谷胱甘肽过氧化物酶（GPX）、谷胱甘肽还原酶（GR）、过氧化氢酶（CAT）、谷胱甘肽转移酶（GST）的活性,观察术中肺萎陷质量。结果 与TLV组比较,T1～T6时OLV-0组和T4～T6时OLV-3组Qs/Qt明显升高、PaO2明显降低（P〈0.05或P〈0.01）。与T0时比较,T2～T6时OLV-0组和T4～T6时OLV-3组Qs/Qt明显升高、而PaO2明显降低（P〈0.05或P〈0.01）。与TLV组比较,T1～T6时OLV-0组四种酶及OLV-3组GR、CAT、GST活性明显下降（P〈0.05）,而T5、T6时OLV-3组GPX活性明显下降（P〈0.05）。与T0时比较,T1～T6时OLV-0、OLV-3组CAT、GR、GST活性明显下降（P〈0.05）,而T4～T6时OLV-0组和T6时OLV-3组GPX活性明显下降（P〈0.05）,在单肺通气期间OLV-6、OLV-9组四种内源性抗氧化酶的活性差异无统计学意义。OLV-0、OLV-3及OLV-6组术侧肺萎陷质量Ⅰ级例数明显多于OLV-9组（P〈0.05）。结论单肺通气期间非通气侧肺实施6cm H2O的CPAP和9cm H2O的CPAP可明显提高患者氧分压,减少Qs/Qt,增加内源性抗氧化酶的活性,且6cm H2O的CPAP更有利于手术的操作。

Objective To investigate the effects of non-ventilated lung with CPAP at different levels on systemic oxygenation and intrapulmonary shunt and changes of endogenous antioxidant en- zymes （GPX,GR,CAT,GST） during one lung ventilatin （OLV）. Methods Forty ASA I or Ⅱ pa- tients scheduled for esophagectomy were randomly divided into five groups with 8 cases each： two- lung ventilation group （group TLV）, one-lung ventilation group （group OLV-0）, OLV with 3 cm H2O CPAP group（group OLV-3）, OLV with 6 cm H2O CPAP group（group OLV-6） and OLV with 9 cm H2 O CPAP group（group OLV-9）. Venous blood samples and blood gas analysis were taken after induction at supine position before incision （T0）, at 15 rain（T1 ）, 30 min （T2）, 60 min （T3）, 90 min （T4）, 120 rain （T5）, 150 min（T6 ） after one-lung ventilation at lateral position and at the end of operation with two lung ventilation （T7） for measuring activities of the endogenous antioxidant en- zymes and calculating pulmonary shunt fraction. The degree of lung cllapse was compared during OLV in various one-lung ventilation groups. Results Compared with group TLV, Qs/Qt was increased and PaO2 was decreased in group OLV-O at T1-T6 and group OLV-3 at T4-T6 （P〈0. 05）. Compared with To, Qs/Qt was increased and PaO2 was decreased in group OLV-0 at T2-T6 and group OLV-3 at T4-T6 （P〈0.05）. Activities of four kinds of endogenous antioxidant enzymes in group OLV-0 and activi- ties of CAT,GR,GST in group OLV-3 were decreased at T1-T6, while GPX was decreased at T5, T6 in group OLV-3 compared with group TLV（P〈0. 05）. Compared with To, activites of CAT, GR, GST were decreased in group OLV-0 and OLV-3 at T1-T6, GPX was decreased in OLV-0 at T4-T6 and in OLV-3 at T6 （P〈0.05）, there were no significant differences in activites of four kinds of enzymes in group OLV-6 and OLV-9 during OLV. The number of first degree lung collapse in group OLV-0, OLV-3 and OLV-6 and OLV-6 was much more than group OLV-9（P〈0.05）. Conclusion CPAP at 6 cm H2O and 9 cm H2O levels during one lung ventilation can enhance activities of endogenous antioxi- dant enzymes, significantly improve oxygenation and reduce intrapulmonary shunt. Moreover, CPAP at 6 cm H2O leads to a better surgical field during OLV.