Intraoperative mechanical power and postoperative pulmonary complications in non-cardiothoracic elective surgery patients: a ten-year retrospective cohort-study.

BACKGROUND: Postoperative Pulmonary Complications (PPC) is a major issue that impacts outcomes of surgical patients. Our hypothesis was that the intraoperative ventilation parameters are associated with occurrence of PPCs.

METHODS: We conducted a single-center retrospective cohort-study at the Lille University Hospital, France. We included 33701 adults undergoing non-cardiac non-thoracic elective surgery requiring general anesthesia with tracheal intubation between January 2010 and December 2019. We compared intraoperative ventilation parameters between patients with and without one or more PPC (respiratory infection, respiratory failure, pleural effusion, atelectasis, pneumothorax, bronchospasm, and aspiration pneumonitis) within 7 days of surgery.

RESULTS: Among 33701 patients, 2033 (6.0%) had one or more PPCs. Lower Tidal Volume to Predicted Body Weight ratio (OR per -1 ml.kgPBW-1: 1.08 95%CI: 1.02 to 1.14, p<0.001), higher mechanical power (OR per 4J.min -1: 1.37, 95%CI: 1.26 to 1.49, p<0.001), dynamic respiratory system compliance < 30 ml.cmH2O, (1.30 [1.15 to 1.46], p<0.001), SpO2 below 96% (OR: 2.42, 95%CI: 1.97 to 2.96, p<0.001) and lower EtCO2 (OR per -3 mmHg: 1.06, 95%CI: 1.00 to 1.13, p=0.023) were independently associated with PPCs. Patients with PPCs were more likely to be admitted to the Intensive Care Unit (OR: 12.5, 95%CI: 6.6-10.1, p<0.001), had longer hospital Length of stay (sHR: 0.43, 95CI: 0.40-0.45), and higher in-hospital (sHR: 6.0, 95%CI: 4.1-9.0, p<0.001) and 1-year mortality (sHR: 2.65, 95%CI 2.33-3.02, p<0.001).

CONCLUSIONS: In our population, decreased rather than increased tidal volume, decreased compliance, increased mechanical power, and decreased EtCO2 were independently associated with PPCs.