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（体外循环肺辅助：ECLA）呼吸支持下双侧肺完全和长期液体充盈的生理影响。在百草枯致急性肺损伤模型上，正常杂种犬气管内滴入温热的乳酸林格氏液，在静-动脉ECLA下，以15cmH_2O的静水压力使双肺完全充盈4小时，虽然肺动脉氧分压（PaO_2）在完全充盈后迅速下降，但肺动脉氧分压（PaO_2）在完全充盈后迅速下降，而肺动脉氧分压（PaO_2）在完全充盈后迅速下降。在液体引流后迅速升高，并在随后的研究期间保持相对较高的水平。引流液体后的胸部X线片显示双肺扩张且通气良好。在整个实验期间，总静态肺顺应性也保持不变。与对照犬相比，尸检时左肺水的重量未增加。组织学检查表明肺泡或肺泡内无液体潴留。所有犬均能在24小时内从ECLA撤至常规机械通气和自主呼吸，而不影响气体交换和肺顺应性，用百草枯（methlybiologen）15 mg/kg静脉注射建立急性肺损伤模型。百草枯给药后6天，对肺进行了长时间液体充盈。尽管在液体引流后进行了机械气体通气，但肺完全没有膨胀，犬无法脱离ECLA。另一方面，在百草枯给药次日进行液体填充的犬可以恢复良好，并且在液体引流后可以脱离ECLA。结果表明，在肺损伤的极急性期，双肺的液体充盈可以恢复，而没有严重的肺损伤，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.