Comparison of low vs high tidal volumes in one-lung ventilation during thoracic surgery: a propensity-weighted cohort...

The optimal tidal volume (TV) during one-lung ventilation (OLV) for thoracic surgery remains uncertain. This study aimed to evaluate the association between intraoperative tidal volume and the incidence of postoperative respiratory complications in patients undergoing thoracic surgery. We conducted a post-hoc analysis of single-center observational cohort study who underwent elective thoracic surgery with OLV between January 2015 and January 2021. Patients were categorized according to their mean intraoperative TV: < 5 mL/kg versus ≥ 5 mL/kg predicted body weight (PBW). The primary outcome was postoperative respiratory complications (PRCs) within 7 days. Secondary outcomes included other major complications and 30-/90-day mortality. Analyses were adjusted using propensity score overlap weighting. Sensitivity analyses included an alternative 6 mL/kg threshold and stratified analyses by TV range. A post hoc Bayesian analysis was also performed. We included 1,234 patients. PRCs occurred in 37/458 (8.1%) patients in the < 5 mL/kg group and 45/776 (5.8%) in the ≥ 5 mL/kg group. After adjustment, TV < 5 mL/kg was not associated with a reduced risk of PRCs (RR, 1.07; 95% CI, 0.69-1.66). Using a 6 mL/kg threshold yielded similar findings (RR, 0.93; 95% CI, 0.47-1.82). Stratified analyses by tidal volume range (> 4, 4-5, 5-6, and > 6 mL/kg) showed no significant association between tidal volume and PRCs. However, TV < 5 mL/kg was associated with an increased risk of postoperative atrial fibrillation (RR, 1.50; 95% CI, 1.09-2.05). Bayesian analyses showed no evidence of a beneficial effect of TV < 5 mL/kg on the composite outcome of postoperative complications, even when using favorable prior assumptions. In this cohort, tidal volumes < 5 mL/kg during OLV were not associated with a lower incidence of postoperative respiratory complications.