俯卧位通气联合呼气末正压治疗急性呼吸窘迫综合征家猪的疗效研究

Influence of combining positive end-expiratory pressure with prone position on acute respiratory distress syndrome in pig

目的探讨俯卧位通气联合呼气末正压（PEEP）治疗急性呼吸窘迫综合征（ARDS）的疗效及其机制。方法12头家猪静脉注射油酸建立ARDS模型，分为仰卧位组和俯卧位组，均给予0（ZEEP）、10（PEEP10）、20cm H2O（PEEP20，1cmH2O=0．098kPa）PEEP的机械通气15min，监测家猪血流动力学、肺气体交换和呼吸力学指标；处死动物观察肺组织病理学变化。结果俯卧位组ZEEP、PEEP10时氧合指数（PaO2／FiO2）明显优于仰卧位组[ZEEP：（234．00±72．55）mmHg比（106．58±34．93）mmHg，PEEP10：（342．97±60．15）mmHg比（246．80±83．69）mmHg，1mmHg=0．133kPa，P均〈0．05]；PEEP20时两组PaO2／FiO2差异无统计学意义（P〉0．05）。PEEP10时两组肺复张容积（RV）差异无统计学意义（P〉0．05）；但PEEP20时俯卧位组RV显著高于仰卧位组[（378．55±101．80）ml比（302．95±34．31）ml，P〈0．053。两组间心率（HR）、平均动脉压（MAP）、心排血指数（CI）、呼吸系统顺应性（Cst）及动脉血二氧化碳分压（PaCO2）差异均无统计学意义（P均〉0．05）；仰卧位组背侧肺组织的肺损伤总评分明显高于俯卧位组[（12．00±1．69）分比（6．03±1．56）分，P〈0．053。结论俯卧位通气联合合适的PEEP可改善ARDS家猪氧合，并且不影响血流动力学和呼吸力学，肺组织损伤的重新分布可能是其机制之一。

Objective To determine the effect of combining positive end-expiratory pressure （PEEP） with prone position during acute respiratory distress syndrome （ARDS） and its mechanism. Methods Twelve healthy pigs were randomly divided into two groups according to the body posture during mechanical ventilation after oleic acid-induced lung injury： supine position group and prone position group. Three different PEEP levels of 0 （ZEEP）, 10 （PEEP10） and 20 cm H20 （PEEP20, 1 cm H2O=0. 098 kPa） were applied to each group one after another. Hemodynamics, respiratory mechanics and gas exchange were measured 15 minutes after each PEEP level was applied, and lung specimens for pathological examination were harvested after sacrifice of the animals. Results Compared to supine position, prone position improved oxygenation index （PaO2/FiO2） at ZEEP and PEEP10 [ZEEP： （234.00± 72.55） mm Hg vs. （106.58± 34.93） mmHg, PEEP10： （342. 97±60.15） mm Hg vs. （246. 80±83.69） mmHg, 1 mm Hg=0.133 kPa, both P〈0. 053, but not at PEEP20. No significant difference in heart rate （HR）, mean arterial pressure （MAP）, cardiac index （CI）, compliance of the respiratory system （Cst） and partial pressure of arterial carbon dioxide （PaCO2） were observed between groups at three PEEP levels. Compared with supine position, lung recruited volume （RV） was elevated in prone position at PEEP20 [（378. 55± 101.80） ml vs. （302.95±34.31） ml, P〈0. 053, but not at PEEP10. In supine group the dorsal regions of the lungs showed more severe injury than that in prone group （12.00±1.69 vs. 6.03±1.56, P〈0.05）. Conclusion In pigs with ARDS, prone position improves PaO/FiO2 significantly without influence on respiratory mechanics and hemodynamics. Redistribution of lung injury may be one of the mechanisms of its beneficial effect.