压力-容量曲线对急性肺损伤家兔实行个体化保护性通气的应用

Application of pressure volume curve on individual lung-protective ventilation in rabbits with acute lung injury

目的研究以压力容量（P-V）曲线确定通气参数对急性肺损伤家兔肺的保护作用。方法新西兰家兔24只，随机分为4组（V1P1、V1P2、V2P1、V2P2），每组4只。用油酸复制急性肺损伤模型，测定P-V曲线，以下曲点压力（Pinf）和上曲点压力（Pdef）分别选择呼气末正压（PEEP）的两水平：P1＝PinfP2＝Pinf－3cmH2O，潮气量（VT）两水平：V1＝15ml／kg，V2下调使平台压小于上曲点压力（Pplat＜Pdef）。观察肺力学、血气、血循环及肺病理改变。结果4组氧合效果基本相同，动脉血二氧化碳分压（PaCO2）和pH主要受VT影响。平均动脉压在大PEEP和（或）大VT时有所下降。呼吸系统静态顺应性（Cst）则以PEEP为Pinf时改善最明显，但大VT抵消了其作用且对肺泡有明显的损伤。小PEEP组肺泡透明膜变加重。结论以呼吸系统P-V曲线选择PEEP和VT进行个体化通气，对肺的力学特性和肺的病理性损伤有明显的保护作用，可能有利于改善急性肺损伤的预后。

] Objective To explore the lung-protective effect of ventilation with tidal volume and PEEP determined on pressure-volume curve in oleic acid rabbit models of acute lung injury. Methods 24 New Zealand rabbits were randomly divided into 4 groups(V1P1, V1P2, V2P1, V2P2). the inducing lung injury, the P-V curves were measured and drawn. The low and upper inflection point pressure (Pinf and Pdef respectively) were manually determined. Two levels of tidal volume (V1=15 ml/kg, V2 reduced for Pplat <Pdef) and two levels of PEEP (P1 =Pinf, P2 = Pinf-3 cm H2O) were selected. The peak airway pressure (PIP), plateau pressure (Pplat), mean pressure (PAW), static compliance (Cst), heart rate, arterial blood pressure and blood-gas analysis were measured. The lung tissues were pathologically analyzed with light microscope. Results The oxygenation was not significantly different among 4 groups.The reduced VT significantly raised PaCO2 and lowered pH. Larger VT reduced arterial blood pressure.VT and PEEP synergetically raised airway pressure.Larger PEEP improved Cst, which was counteracted by larger VT. Reduced VT significantly lessened alveolar barotrauma.Larger PEEP lightened alveolar hyaline membrane formation and hemorrhage. Conclusion The ventilation with VT and PEEP determined on P-V curve has significant protective effect on the acutely injured lung.