Intra‐operative ventilation strategies and their impact on clinical outcomes: a systematic review and network meta‐analysis of randomised trials

INTRODUCTION: Postoperative pulmonary complications are common and associated with significant morbidity and mortality; however, the optimal intra-operative ventilation strategy to prevent postoperative pulmonary complications remains unclear. The aim of this study was to evaluate the effect of intra-operative ventilation strategy, including tidal volumes, positive end-expiratory pressure (PEEP) and use of recruitment manoeuvres on the incidence of postoperative pulmonary complications in adults having non-cardiothoracic surgery. METHODS: Relevant databases were searched to identify randomised controlled trials that directly compared intra-operative ventilation strategies among surgical patients who were followed up for > 24 hours postoperatively and reported at least one outcome of interest. RESULTS: A total of 51 randomised controlled trials were included. Compared with a high tidal volume/zero PEEP strategy, low tidal volume strategies likely reduced the risk of postoperative pulmonary complications when combined with: high PEEP (risk ratio (RR) 0.44, 95%CI 0.22-0.87); high PEEP with recruitment manoeuvres (RR 0.60, 95%CI 0.49-0.75); personalised PEEP with recruitment manoeuvres (RR 0.53, 95%CI 0.42-0.69); low PEEP (RR 0.63, 95%CI 0.50-0.78); and low PEEP with recruitment manoeuvres (RR 0.65, 95%CI 0.46-0.93) (all moderate certainty evidence). Compared with a low tidal volume/low PEEP strategy, a low tidal volume strategy with personalised PEEP likely reduces the risk of postoperative pulmonary complications (RR 0.85, 95%CI 0.73-0.99, moderate certainty). DISCUSSION: Among patients undergoing non-cardiothoracic surgery, the use of intra-operative low tidal volume ventilation with a range of acceptable PEEP levels likely reduced the risk of postoperative pulmonary complications compared with high tidal volumes and zero PEEP. This study highlights the need for implementation research at both the provider and system levels to improve intra-operative adherence to lung protective ventilation strategies.