Fig. 4.

Trial sequential analysis assessing the effects of PEEP and/or recruitment manoeuvres on mortality (collapsed at 28 days, ICU discharge, hospital discharge). Required information size of 2487 patients (dotted line) is calculated for a relative risk reduction of 25%, α = 5%, power (1-β) = 80%. The Z-line (blue line) of the cumulative meta-analysis of 3757 patients did not cross the efficacy monitoring boundaries for benefit or harm (grey area) but entered the futility wedge (light blue area). Horizontal dashed lines represent the conventional level of significance (p = 0.05)