Association of preoperative forced vital capacity with prolonged mechanical ventilation after coronary artery bypass grafting: a retrospective cohort Study

Prolonged mechanical ventilation (PMV) is a serious complication after coronary artery bypass grafting (CABG), yet the association between preoperative pulmonary function and PMV risk remains to be comprehensively evaluated. This study included adult patients who underwent isolated CABG with preoperative pulmonary function testing. Predicted forced vital capacity (FVC), predicted forced expiratory volume in 1 s (FEV₁), and the FEV₁/FVC ratio were assessed for their association with PMV. Among 1,702 patients, 151 (8.9%) experienced PMV. Patients with PMV were older (65.1 ± 8.5 vs. 62.8 ± 8.8 years, P = 0.003), had higher rates of chronic obstructive pulmonary disease (9.9% vs. 5.4%, P = 0.034) and on-pump CABG (8.6% vs. 1.2%, P < 0.001), lower left ventricular ejection fraction (57.1 ± 10.3% vs. 59.1 ± 8.7%, P = 0.007), lower predicted FVC (82.9 ± 14.0% vs. 88.1 ± 14.9%, P < 0.001), and lower predicted FEV₁ (88.7 ± 15.5% vs. 92.6 ± 16.2%, P = 0.007). They also had higher perioperative mortality (4.0% vs. 0.1%, P < 0.001), longer postoperative hospital stays (10.9 ± 4.2 vs. 8.0 ± 2.6 days, P < 0.001), and greater hospitalization costs (25,309.4 [22,119.4–33,359.3] vs. 18,155.4 [16,665.8–20,001.5] USD, P < 0.001). Restricted cubic spline analysis showed no non-linear relationship between pulmonary function parameters and PMV. After multivariable adjustment, predicted FVC remained independently associated with PMV (odds ratio [OR] 0.97, 95% confidence interval [CI] 0.95–0.99, P = 0.005), whereas predicted FEV₁ did not. Nearly one-tenth of patients undergoing CABG required PMV, which was associated with greater healthcare resource utilization and higher perioperative complications. Predicted FVC, but not predicted FEV₁, is an independent predictor of PMV.