Rationale: Recent literature in mechanical ventilation includes strong evidence from randomized trials. Little information is available regarding the influence of these trials on usual clinical practice.

Objectives: To describe current mechanical ventilation practices and to assess the influence of interval randomized trials when compared with findings from a 1998 cohort.

Methods: A prospective international observational cohort study, with a nested comparative study performed in 349 intensive care units in 23 countries. We enrolled 4,968 consecutive patients receiving mechanical ventilation over a 1-month period. We recorded demographics and daily data related to mechanical ventilation for the duration of ventilation. We systematically reviewed the literature and developed 11 practice-change hypotheses for the comparative cohort study before seeing these results. In assessing practice changes, we only compared data from the 107 intensive care units (1,675 patients) that also participated in the 1998 cohort (1,383 patients).

Measurements and Main Results: In 2004 compared with 1998, the use of noninvasive ventilation increased (11.1 vs. 4.4%, P < 0.001). Among patients with acute respiratory distress syndrome, tidal volumes decreased (7.4 vs. 9.1 ml/kg, P < 0.001) and positive end-expiratory pressure levels increased slightly (8.7 vs. 7.7 cm H₂O, P = 0.02). More patients were successfully extubated after their first attempt of spontaneous breathing (77 vs. 62%, P < 0.001). Use of synchronized intermittent mandatory ventilation fell dramatically (1.6 vs. 11%, P < 0.001). Observations confirmed 10 of our 11 practice-change hypotheses.

Conclusions: The strong concordance of predicted and observed practice changes suggests that randomized trial results have advanced mechanical ventilation practices internationally.