Postoperative Outcomes Following Prolonged One Lung Ventilation in thoracic surgery in relation to intraoperative ventilation practiced: A Registry-Based Multicenter Study

Objectives To evaluate the association between intraoperative ventilation parameters during prolonged one-lung ventilation (OLV) and postoperative outcomes. Design Retrospective multicenter cohort study. Setting German Thoracic Registry. Participants 2,026 patients who underwent thoracic surgery with OLV >60 min between 2016 and 2021. Interventions None. Measurements and Main Results Parameters included peak pressure-derived driving pressure (DP), calculated as pMax minus PEEP, peak airway pressure (pMax), positive end-expiratory pressure (PEEP), and tidal volume per predicted body weight (TV/PBW). Primary outcomes were overall postoperative complications and respiratory complications; in-hospital mortality was analyzed as a secondary outcome. Postoperative complications occurred in 34.1%, respiratory complications in 18.6%, and in-hospital mortality in 1.8%. In unadjusted analyses, higher overall postoperative complication rates were observed above several ventilation thresholds, including DP >20 mbar, pMax >25 and >30 mbar, PEEP >7 and >8 mbar, and TV/PBW >4 and >5 mL/kg PBW (all p < .05). Higher overall postoperative complication rates were also observed for OLV duration >180 min compared with 61–90 min and for surgical duration >180 min compared with 31–60 min (both p < .001). Respiratory complications were significantly associated with DP >20 mbar (p = .009; DP >25 mbar: p = .013), pMax >25 mbar (p < .001; pMax >30 mbar: p = .022), TV >5 mL/kg PBW (p = .032). Respiratory complication rates were also higher for OLV duration >180 min compared with 61–90 min and for surgical duration >180 min compared with 31–60 min (both p < .001). In-hospital mortality was significantly associated with DP >20 mbar (p = .023), pMax >25 mbar (p = .017; pMax >30 mbar: p < .001), PEEP >8 mbar (p = .027), and TV >8 mL/kg PBW (p = .034), but analysis was limited by the low number of events (n = 37). Conclusions Several pressure-, volume-, and duration-related thresholds were associated with higher postoperative morbidity and in-hospital mortality in unadjusted analyses. These findings should not be interpreted as evidence to reduce PEEP routinely during OLV. In adjusted models, baseline patient risk and case complexity markers were the main contributors, suggesting that higher PEEP may partly reflect confounding by indication, intraoperative physiology, and procedural complexity. Prospective validation is warranted.