Lung morphology predicts response to recruitment maneuver in patients with acute respiratory distress syndrome

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Abstract
He pulmonary distribution of aeration loss, predict the response to recruitment maneuvers. Design: Prospective study. Setting: A 16-bed medical–surgical intensive care unit in a university hospital. Measurements and Main Results: Nineteen consecutive patients with early acute lung injury/acute respiratory distress syndrome were studied. Computed tomography scans, respiratory mechanics, hemodynamics, and gas exchange were obtained at zero end-expiratory pressure during an open-lung ventilation (controlled mode, tidal volume 6 mL/kg of ideal body weight, positive end-expiratory pressure set 2 cm H2O above the lower inflection point of the inspiratory pressure volume curve at zero end-expiratory pressure) during a recruitment maneuver (continuous positive airway pressure of 40 cm H2O for 40 secs), and, finally, 5 mins after the recruitment maneuver during open-lung ventilation. Nine patients presented focal and 10 presented nonfocal lung morphology at zero end-expiratory pressure. Recruitment maneuver-induced recruited volume after 5 mins of open-lung ventilation was 48 ± 66 mL and 417 ± 293 mL in patients with focal and nonfocal lung morphology, respectively (p = .0009). Recruitment maneuver-induced alveolar hyperinflation represented 23% ± 14% and 8% ± 9% of total lung volume in patients with focal and nonfocal morphology, respectively (p = .007). In patients with focal lung morphology, hyperinflated lung volume was significantly greater during and 5 mins after (316 ± 155 mL) than immediately before recruitment maneuvers (150 ± 175 mL; p = .0407. Conclusion: Lung morphology at zero end-expiratory pressure predicts the response to recruitment maneuvers. Patients with focal lung morphology are at risk for significant hyperinflation during the recruitment maneuvers, and lung recruitment is rather limited....