氧浓度对体外循环后肺损伤影响的实验研究

目的：观察体外循环(CPB)前后吸入不同浓度氧气对肺脏缺血／再灌注损伤的影响。方法：建立大鼠体外循环模型，体外循环时间为120min。根据机械通气期间吸入氧浓度的不同分100％氧通气组(n=8)和50％氧通气组(n=8)。实验过程记录血压和心率的变化，并进行血气分析。CPB后60min实验结束时取肺组织。测定并计算丙二醛(MDA)、髓过氧化物酶(MPO)和组织含水量。结果：体外循环前后血压和心率相对稳定。体外循环过程中红细胞压积(HCT)和转流量两组没有明显差异。100％氧通气组的PaO2在CPB结束后5min和CPB后60min均低于CPB前，而50％氧通气组没有明显变化，而且CPB后肺组织中MDA和MP0较低．肺组织含水量也低于100％氧通气组。结论：体外循环前后吸入高浓度氧可加重氧化性肺损伤，应使用接近生理水平的较低浓度的氧气以减轻肺损伤。

Experimental research on effects of oxygen concentration on lung injury after cardiopulmonary bypass

Objective To investigate the effect of ventilation with 100% and 50% oxygen on lung injury associated with cardiopulmonary bypass (CPB). Methods Sixteen Sprague-Dawley rats were randomized to receive 100% oxygen or 50% oxygen to ventilation before and after CPB. Changes of blood pressure (BP) and heart rates (HR) were recorded and blood gas analysis was made during the experiment. Lung tissues were taken and restored for the assay of MDA, MPO and water content. Results BP and HR remained unchanged before and after CPB. There was no significant difference on HCT and rates of pump during CPB. PaO 2 decreased 5 and 60 minutes after CPB compared with pre-CPB in the group of 100% oxygen (P<0.05). Rats receiving 100% oxygen were found to have higher contents of MDA, MPO and water in lung tissues than those receiving 50% oxygen. Conclusion High oxygen concentration in ventilation before and after CPB can induce severer lung injury and physiological oxygen concentration should be used because of its usefulness in reducing ischemia/reperfusion related-lung injury.