Recruitment maneuvers in three experimental models of acute lung injury. Effect on lung volume and gas exchange.

Recruitment maneuvers (RM), consisting of sustained inflations at high airway pressures, have been advocated as an adjunct to mechanical ventilation in acute respiratory distress syndrome (ARDS). We studied the effect of baseline ventilatory strategy and RM on end-expiratory lung volume (EELV) and oxygenation in 18 dogs, using three models of acute lung injury (ALI; n = 6 in each group): saline lavage (LAV), oleic acid injury (OAI), and intratracheal instillation of Escherichia coli (pneumonia; PNM). All three models exhibited similar degrees of lung injury. The PNM model was less responsive to positive end-expiratory pressure (PEEP) than was the LAV or OAI model. Only the LAV model showed an oxygenation response to increasing tidal volume (Vt). After RM, there were transient increases in PaO2 and EELV when ventilating with PEEP = 10 cm H2O. At PEEP = 20 cm H2O the lungs were probably fully recruited, since the plateau airway pressures were relatively high ( ≈ 45 cm H2O) and the oxygenation was similar to...