体位改变对急性肺损伤兔肺功能与CT及病理的影响

The effect of body position changes on lung function,lung CT imaging and pathology in an oleic acid-induced acute lung injury model

目的 通过观察不同体位下急性肺损伤 (ALI)肺的氧合功能、呼吸力学、肺CT以及病理等的变化 ,来探讨不同体位的效应和可能机制。方法 采用油酸型ALI兔模型 ,分为正常对照组(Ⅰ组 )、仰卧位油酸组 (Ⅱ组 )、俯卧位油酸组 (Ⅲ组 )、旋转体位油酸组 (Ⅳ组 ) ,观察各组兔实验过程中动脉血氧分压 (PaO2 )、呼吸力学的变化。并进行肺CT扫描加以分析 ,最后作病理切片检查。结果Ⅲ、Ⅳ组的PaO2 [(15 8± 5 1)、(16 6± 37)mmHg]、肺的顺应性 [(2 8± 0 9)、(2 6± 0 7)ml/cmH2 O]显著高于Ⅱ组 [PaO2 (87± 2 4 )mmHg、肺的顺应性 (1 6± 0 5 )ml/cmH2 O ,P均 <0 0 5 ];Ⅲ、Ⅳ组肺内分流 [(2 1± 5 ) %、(18± 5 ) % ]显著低于Ⅱ组 [(2 9± 8) % ,P <0 0 5 ];Ⅳ组的气道峰压 [(2 0± 2 )cmH2 O]显著高于Ⅲ组 [(16± 2 )cmH2 O ,P <0 0 5 ];3个实验组的PaO2 与肺的顺应性呈显著正相关 ,与肺内分流呈显著负相关。ALI兔肺CT呈明显的重力依赖效应 ,体位的变化对肺CT的影响非常迅速。肺水肿在重力依赖区重 ,旋转后 ,重力依赖现象减轻。结论 俯卧位和旋转体位都能改善兔油酸型ALI肺的氧合 ;ALI肺出现重力压迫性肺不张 ,旋转体位能减轻肺不张的程度和使肺水肿趋于均匀。

Objective To study the effect of body position changes on lung mechanics,oxygenation,CT images and pathology in an oleic acid-induced acute lung injury(ALI) model. Methods The study groups consisted of one control group and three experimental groups in which the rabbits were put on supine,prone and rotation,respectively. The changes of partial pressure of arterial oxygen(PaO 2),lung mechanics in the course of the experiment,as well as lung CT and pathology were observed and analyzed. Results PaO 2 and lung compliance of the prone and the rotation rabbits were higher than those of the supine rabbits [(158±51)mm Hg,(166±37)mm Hg,(87±24)mm Hg;(2.8±0.9)ml/cm H 2O,(2.6±0.7)ml/ cm H 2O,(1.6±0.5)ml/cm H 2O,respectively,all P<0.05],while intrapulmonary shunt was significantly less in the prone and the rotation groups. The airway peak inspiration pressure of the rotation rabbits was higher than that of the prone rabbits[(20±2)cm H 2O,(16±2)cm H 2O,P<0.05]. PaO 2 was positively correlated to the lung compliance and negatively correlated to the intrapulmonary shunt. Oleic acid-induced ALI lung CT was divided into dependent region and nondependent region,and the CT changes of the two regions were rapid after position change. The distribution of lung edema was affected by gravitation. Conclusions Prone and rotation positions can improve oxygenation in this ALI model. Continuous rotation can relieve the extent of compressive lung collapse which occurs in ALI.