肺动脉灌注压力对体外循环后肺功能的影响

Effects of different pulmonary artery perfusion pressures on cardiopulmonary bypass-induced pulmonary function injury

目的本实验在之前研究的基础上进一步探索体外循环过程中,保护液肺动脉灌注时,不同的灌注压力对体外循环后肺功能的影响。方法 20只健康家犬随机平均分为一个对照组及三个灌注组,模拟临床体外循环肺损伤特点建立动物模型。体外循环期间,分别以三个不同的压力段(低:15～20 mm Hg,中:25～30 mm Hg,高:40～45 mm Hg)对灌注组动物实验肺实施保护液灌注,对照组动物无保护液灌注。90 min体外循环肺缺血后,再灌注4 h,行实验肺肺功能变化测定。结果较之基础值,4组动物实验肺各项肺功能指标均有不同程度的恶化。较之对照组,中压灌注组各指标的变化幅度均明显减低。较之中压组,低压组的变化幅度进一步减低。高压组各指标的变化幅度稍低于对照组,但无明显统计学意义。结论体外循环过程中,保护液肺动脉灌注可有效缓解体外循环后肺功能损害。灌注压力是影响肺保护效果的重要因素,30 mm Hg以下的灌注压力是安全而有效的,15～20 mm Hg的效果更佳;高至40～45 mm Hg的灌注压力,未见明显有益的肺保护效应。不同灌注压力下的液体流量负荷和对肺血管内皮细胞的机械应力,可能是灌注压力影响肺保护效果的重要机制。

Objective Reducing lung injury during cardiopulmonary bypass （CPB） is important for patients＇recovery. On the basis of prevenieut experiments, the present study was designed to evaluate the effects of pulmonary artery perfusion pressure on the extent of lung function injury during CPB in an animal model. Methods Twenty healthy mongrel clogs were randomly divided into four groups （5 for each group）, including a control group and three pefusion groups designed to simulate clinical cardiopulmonary bypass - induced lung injury. During pulmonary iscbemla and CPB, protective perfusions were performed using different perfusion pressures （ 15 -20, 25 -30, and40 -45 mm Hg） , while animals in the control group were not peffusod. After pulmonary reperfusion, the changes in pulmonary function were determined. Results Compared with the control group, lung compliance, oxygenation and vascular resistance after repeffusion were significantly improved in both low - and moderate - pressure groups, and in the low - pressure group the improvement was more significant. However, there were no significant differences in any of these parameters between the control group and the high - pressure group. Conclusion The perfusion pressure is an important factor that determines the extent of lung protection, and the use of pressures below 30 mm Hg is optimal, with the safest and most effective range being 15 -20 mm Hg. When the pressure is further elevated to 40 -45 mmHg, there is no obvious benefit found compared to the control group. The volume load of perfusate and mechanical stress forces exerted on the lung due to different perfusion pressures may be the important mechanism influencing the protection effect.