Pulmonary complications occur frequently after cardiac surgery. Various intraoperative and perioperative mechanical ventilation strategies were investigated to reduce postoperative lung injury. Evidence of their benefits remains inconclusive.

We performed a systematic review and meta-analysis of RCTs investigating ventilation strategies applied during the preoperative, intraoperative, or postoperative period of cardiac surgery requiring cardiopulmonary bypass. The primary outcome was all-cause mortality. Secondary outcomes included the rate of infections, postoperative pulmonary complications, and the duration of mechanical ventilation.

We identified 105 RCTs. We conducted a meta-analysis of the 39 studies suitable for quantitative synthesis. Postoperative pulmonary complications were reduced when using ventilation during cardiopulmonary bypass (risk ratio [RR]=0.87; 95% confidence interval [CI]=0.79 to 0.96; P=0.005; I²=0%, with 15 studies included). Mortality was 17/414 (4.1%) in patients receiving postoperative noninvasive respiratory support vs 24/377 (6.4%) in control group patients (RR=0.60; 95% CI=0.34 to 1.08; P=0.09; I²=0%, with five studies included). Pressure-controlled vs volume-controlled ventilation during surgery and adaptive support ventilation vs conventional ventilation in the postoperative period were not associated with improvements in primary or secondary outcomes.

Ventilation strategies in cardiac surgery remain highly heterogeneous regarding protocols and timing. Ventilation during cardiopulmonary bypass significantly reduced postoperative pulmonary complications. Postoperative noninvasive respiratory support showed a non-significant trend toward improved survival and remains hypothesis-generating. Additional evidence is required to validate these results.