Recruitment maneuvers to reduce pulmonary atelectasis after cardiac surgery: A meta-analysis of randomized trials

Pulmonary atelectasis is a common postoperative complication that may lead to intrapulmonary shunt, refractory hypoxemia, and respiratory distress. Recruitment maneuvers may relieve pulmonary atelectasis in patients undergoing cardiac surgery. We conducted a meta-analysis of randomized controlled trials to evaluate the effectiveness of recruitment maneuvers in these patients.

We conducted a search in PubMed, Embase, Cochrane Library, and the ClinicalTrials.gov registry for trials published before March 2020. Individual effect sizes were standardized, and a meta-analysis was performed to calculate a pooled effect size by using random-effects models. Pulmonary atelectasis was assessed postoperatively. Secondary outcomes included hypoxic events, arterial oxygen tension (Pao₂)/inspired oxygen fraction (Fio₂) ratio, cardiac index, mean arterial pressure, and postoperative complications including pneumothorax and pneumonia.

We reviewed 16 trials involving 1455 patients. Patients receiving recruitment maneuvers had a reduced incidence of pulmonary atelectasis (group with recruited pressure >40 cmH₂O: risk ratio [RR], 0.20; 95% confidence interval [CI], 0.07-0.57; group with recruited pressure <40 cmH₂O: RR, 0.54; 95% CI, 0.33-0.89), reduced incidence of hypoxic events (RR, 0.23; 95% CI, 0.14-0.37), reduced incidence of pneumonia (RR, 0.42; 95% CI, 0.18-0.95), and improved Pao₂/Fio₂ ratio (weighted mean difference [WMD]; 58.87, 95% CI, 31.24-86.50) without disturbing the cardiac index (WMD, 0.22; 95% CI, -0.18 to 0.61) or mean arterial pressure (WMD, -0.30, 95% CI, -3.19 to 2.59) as compared with those who received conventional mechanical ventilation. The incidence of pneumothorax was nonsignificant between the groups.

Recruitment maneuvers may reduce postoperative pulmonary atelectasis, hypoxic events, and pneumonia and improve Pao₂/Fio₂ ratios without hemodynamic disturbance in patients undergoing cardiac surgery.