Bronchoalveolar lavage alterations during prolonged ventilation of patients without acute lung injury

Mechanical ventilation deteriorates previously injured lung, but little is known about its effect on healthy human lung. This work was designed to assess the effect of prolonged mechanical ventilation on bronchoalveolar lavage (BAL) fluid composition of patients without acute lung injury. Twenty-two ventilated patients (tidal volume 8-10 mL x kg(-1), positive end-expiratory pressure 3-5 cmH2O) without lung injury, who did not develop any complication from the respiratory system during the 2-week study period, were studied. They were subjected to three consecutive BALs, the first during 36 h from intubation, the second at the end of the first week of mechanical ventilation and the third at the end of the second week of mechanical ventilation. Total BAL protein increased during mechanical ventilation (148 +/- 62, 381 +/- 288, 353 +/- 215 microg x mL(-1) BAL for the first, second and third BAL, respectively). In contrast, BAL phospholipids decreased (2.7 +/- 1.1, 1.4 +/- 0.6, 1.2 +/- 0.7 microg x mL(-1) BAL, respectively). Large surfactant aggregates were reduced and inflammatory markers, such as platelet activating factor (PAF), PAF-acetylhydrolase and neutrophils, significantly increased after 1 week, but partially remitted after 2 weeks of mechanical ventilation. In summary, this study demonstrates that prolonged mechanical ventilation even of patients without acute lung injury is associated with the presence of inflammatory markers and surfactant alterations.