Recruitment maneuver: RAMP versus CPAP pressure profile in a model of acute lung injury

We examined whether recruitment maneuvers (RMs) with gradual increase in airway pressure (RAMP) provide better outcome than continuous positive airway pressure (CPAP) in paraquat-induced acute lung injury (ALI). Wistar rats received saline intraperitoneally (0.5 mL, CTRL) or paraquat (15 mg/kg, ALI). Twenty-four hours later lung mechanics [static elastance, viscoelastic component of elastance, resistive, viscoelastic and total pressures] were determined before and after recruitment with 40 cmH(2)O CPAP for 40s or 40-s-long slow increase in pressure up to 40 cmH(2)O (RAMP) followed by 0 or 5 cmH(2)O PEEP. Fractional area of alveolar collapse and PCIII mRNA were determined. All mechanical parameters and the fraction area of alveolar collapse were higher in ALI compared to CTRL Only RAMP-PEEP maneuver significantly improved lung mechanics and decreased PCIII mRNA expression (53%) compared with ALI, while both RMs followed by PEEP decreased alveolar collapse. In conclusion, in the present experimental ALI model, RAMP followed by 5 cm H2O PEEP yields a better outcome. (C) 2009 Elsevier B.V. All rights reserved.