Model-based Identification of Work of Breathing in CPAP Ventilation of Adults

The need for lung protection is universally accepted, but the optimal level of positive end-expiratory pressure (PEEP) in patients with acute lung injury (ALI) or acute respiratory distress syndrome remains debated. To compare the effect on outcome of a strategy for setting PEEP aimed at increasing alveolar recruitment while limiting hyperinflation to one aimed at minimizing alveolar distension in patients with ALI. A multicenter randomized controlled trial of 767 adults (mean [SD] age, 59.9 [15.4] years) with ALI conducted in 37 intensive care units in France from September 2002 to December 2005. Tidal volume was set at 6 mL/kg of predicted body weight in both strategies. Patients were randomly assigned to a moderate PEEP strategy (5-9 cm H(2)O) (minimal distension strategy; n = 382) or to a level of PEEP set to reach a plateau pressure of 28 to 30 cm H(2)O (increased recruitment strategy; n = 385). The primary end point was mortality at 28 days. Secondary end points were hospital mortality at 60 days, ventilator-free days, and organ failure-free days at 28 days. The 28-day mortality rate in the minimal distension group was 31.2% (n = 119) vs 27.8% (n = 107) in the increased recruitment group (relative risk, 1.12 [95% confidence interval, 0.90-1.40]; P = .31). The hospital mortality rate in the minimal distension group was 39.0% (n = 149) vs 35.4% (n = 136) in the increased recruitment group (relative risk, 1.10 [95% confidence interval, 0.92-1.32]; P = .30). The increased recruitment group compared with the minimal distension group had a higher median number of ventilator-free days (7 [interquartile range {IQR}, 0-19] vs 3 [IQR, 0-17]; P = .04) and organ failure-free days (6 [IQR, 0-18] vs 2 [IQR, 0-16]; P = .04). This strategy also was associated with higher compliance values, better oxygenation, less use of adjunctive therapies, and larger fluid requirements. A strategy for setting PEEP aimed at increasing alveolar recruitment while limiting hyperinflation did not significantly reduce mortality. However, it did improve lung function and reduced the duration of mechanical ventilation and the duration of organ failure. clinicaltrials.gov Identifier: NCT00188058.

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