A meta-analysis of intraoperative ventilation strategies to prevent pulmonary complications. Is low tidal volume alone sufficient to protect healthy lungs?

Background: The clinical benefits of intraoperative low tidal volume (LTV) mechanical ventilation with concomittent positive end expiratory pressure (PEEP) and intermittent recruitment maneuvers - termed "protective lung ventilation" (PLV) - have not been investigated systematically in otherwise healthy patients undergoing general anesthesia. Methods: Our group performed a meta-analysis of 16 studies (n = 1054) comparing LTV (n = 521) with conventional lung ventilation (n = 533) for associated postoperative incidence of atelectasis, lung infection, acute lung injury (ALI), and length of hospital stay. A secondary analysis of 3 studies comparing PLV (n = 248) with conventional lung ventilation (n = 247) was performed. Results: Although intraoperative LTV ventilation was associated with a decreased incidence of postoperative lung infection (odds ratio [OR] = 0.33; 95% confidence interval [CI], 0.16-0.68; P = 0.003) compared with a conventional strategy, no difference was noted between groups in incidence of postoperative ALI (OR=0.38; 95% CI, 0.10-1.52; P=0.17) or atelectasis (OR = 0.86; 95% CI, 0.26-2.81; P = 0.80). Analysis of trials involving protective ventilation (LTV + PEEP + recruitment maneuvers) showed a statistically significant reduction in incidence of postoperative lung infection (OR = 0.21; 95% CI, 0.09-0.50; P = 0.0003), atelectasis (OR = 0.36; 95% CI, 0.20-0.64; P = 0.006), and ALI (OR = 0.15; 95% CI, 0.04-0.61; P = 0.008) and length of hospital stay (Mean Difference=-2.08; 95% CI, -3.95 to -0.21; P = 0.03) compared with conventional ventilation. Conclusions: Intraoperative LTV ventilation in conjunction with PEEP and intermittent recruitment maneuvers is associated with significantly improved clinical pulmonary outcomes and reduction in length of hospital stay in otherwise healthy patients undergoing general surgery. Providers should consider application of all the 3 elements for a comprehensive protective ventilation strategy.