最佳呼气末正压对急性呼吸窘迫综合征猪模型肺内分流的影响

Effects of optimal PEEP on pulmonary shunt fraction in pig with acute respiratory distress syndrome

目的:探讨最佳呼气末正压(PEEP)对急性呼吸窘迫综合征(ARDS)猪模型肺内分流(Qs/Qt)的影响。方法:选择油酸静脉注射法复制猪ARDS模型(n=11),应用压力控制法进行肺复张,并根据最佳氧分压+二氧化碳分压法(PaO2+PaCO2)确定最佳PEEP。记录在基础状态、ARDS状态及最佳PEEP水平下,ARDS猪模型的Qs/Qt,气道平台压(Pplat)、静态顺应性(Cst)及动态顺应性(Cdyn)、动脉氧分压(PaO2)、混合静脉血氧分压(PvO2)、动脉血氧饱和度(SaO2)、混合静脉血氧饱和度(SvO2)等参数。并评估PaO2、PvO2、SaO2、SvO2对Qs/Qt的影响。结果:最佳PEEP可明显降低ARDS动物模型的Qs/Qt,P<0.05);Qs/Qt的影响因素大小依次为:SaO2(r2=0.953,P<0.05)、PaO2(r2分别为0.387,P<0.05)、SvO2(r2=0.273,P<0.05),而PvO2对Qs/Qt的影响(P>0.05)无统计学意义。结论:最佳PEEP可有效改善ARDS动物模型的肺内分流,动脉血氧饱和度是影响肺内分流的最主要因素。

Objective To investigate the changes of pulmonary shunt fraction in pig with acute respiratory distress syndrome （ARDS）. Methods Eleven anaesthetized and ventilated ARDS pig models were induced by intravenously infusing oleic acid. Optimal PEEP level was determined by Optimal arterial oxygen partial pressure （PaO2） ＋ arterial carbondioxide partial pressure （PaCO2）. Intrapulmonary shunt fraction （Qs/Qt）, plateau airway pressure （Pplat）, static compliance （Cst）, dynamic compliance （Cdyn）, PaO2, mixed venous oxygen partial pressure （PRO2）, arterial oxygen saturation （SaO2） and mixed venous oxygen saturation （SvO2）, were recorded before infusing oleic acid, after stabilization of ARDS model and at optimal PEEP level. Statistical methods was used to investigate the effects of PaO2, PvO2, SaO2 and SvO2 on Qs/Qt. Results The optimal PEEP can decrease the intrapulmonary shunt （P 〈 0.05）. The effective factors to Qs/Qt were SaO2, PaO2 and SvO2. Qs/Qt was significantly att）cted by SaO2. There was linear correlation between Qs/Qt and SaO2 and the coefficient of determination （ R square） was 0.953 （P 〈 0.05）. PrO2 and SvO2 showed no significant effect on Qs/Qt （P 〉 0.05）. Conclusion The optimal PEEP can improve the intrapulmonary shunt. The main effective factor on Qs/Qt was SaO2.