Recovery of Lung Function after Complete and Prolonged Fluid Filling of Bilateral Lungs under Extracorporeal Lung Assist in Dogs with or without Acute Lung Injury.

我们研究了在体外循环和人工肺(体外肺辅助：ECLA)呼吸支持下，双侧肺完全充液和长时间液体充盈的生理影响。采用百草枯急性肺损伤模型，观察全补液对损伤肺的影响。正常杂种犬气管内注入温热的乳酸林格液，双侧肺在静水压力为15cmH2O的ECLA下充盈4h，PaO2虽在补液后迅速下降，但在引液后迅速回升，并在随后的研究中保持较高水平。引流后胸片显示双侧肺扩张充气良好。在整个实验期间，总静态肺顺应性也保持不变。与对照组相比，尸检时左肺水的重量没有增加。组织学检查显示肺泡或间质内无积液。每只犬均能在引流后24小时内脱离ECLA，转为常规机械通气和自主呼吸，而气体交换和肺顺应性均无恶化。在狗身上。百草枯给药6天后，对肺进行长时间的液体充盈。尽管排液后机械通气，但肺完全没有膨胀，不能脱离ECLA；而在注射百草枯次日补液的狗，恢复良好，排出液体后可以脱离ECLA。结果表明，肺损伤急性期双侧肺的液体充盈可在无严重肺损伤的情况下恢复，与正常动物一样。

We investigated the physiological influence of complete and prolonged fluid filling of bilateral lungs under respiratory support by extracorporeal circulation and an artificial lung (Extracorporeal Lung Assist : ECLA). Then, the effects of complete fluid filling on injured lung was examined in paraquat-induced acute lung injury model.In normal mongrel dogs, warmed lactated ringer's solution was instilled into the endotracheal tube and bilateral lungs were filled completely at a hydrostatic pressure of 15 cmH_2O for 4 hrs under veno-arterial ECLA.Although PaO2 decreased rapidly after fluid filling, it quickly elevated after fluid drainage and remained relatively high in the subsequent study period. Chest roentgenogram obtained after fluid drainage showed that bilateral lungs were expanded and well aerated. Total static lung compliance also remained unchanged throughout the experimental period. The weight of the left lung water at autopsy was not increased compared to that of control dogs. Histological examinations indicated no fluid retention in the alveoli or interstitium of the lung. Every dog could wean from ECLA to conventional mechanical gas ventilation and to spontaneous respiration within 24 hrs after fluid drainage without deterioration in gas exchange or lung compliance.Acute lung injury model was produced by paraquat (methlybiologen) 15 mg/kg i.v. in dogs. Six days after paraquat administration, prolonged fluid filling of the lung was performed. In spite of mechanical gas ventilation after fluid drainage, the lung did not inflate at all and the dog could not wean from ECLA.On the other hand, a dog in which fluid filling was performed on the next day of paraquat administration could recover well and could wean from ECLA after fluid drainage. The results indicate that fluid filling of bilateral lungs in the very acute phase of the lung injury can be recovered without severe lung damage as well as in the normal animal.