Associations Between Expiratory Flow Limitation and Postoperative Pulmonary Complications in Patients Undergoing Cardiac Surgery

Objectives: To determine whether driving pressure and expiratory flow limitation are associated with the development of postoperative pulmonary complications (PPCs) in cardiac surgery patients. Design: Prospective cohort study. Setting: University Hospital San Raffaele, Milan, Italy. Participants: Patients undergoing elective cardiac surgery. Measurements and Main Results: The primary endpoint was the occurrence of a predefined composite of PPCs. The authors determined the association among PPCs and intraoperative ventilation parameters, mechanical power and energy load, and occurrence of expiratory flow limitation (EFL) assessed with the positive end-expiratory pressure test. Two hundred patients were enrolled, of whom 78 (39%) developed one or more PPCs. Patients with PPCs, compared with those without PPCs, had similar driving pressure (mean difference [MD] –0.1 [95% confidence interval (CI), –1.0 to 0.7] cmH2O, p = 0.561), mechanical power (MD 0.5 [95% CI, –0.3 to 1.1] J/m, p = 0.364), and total energy load (MD 95 [95% CI, –78 to 263] J, p = 0.293), but they had a higher incidence of EFL (51% v 38%, p = 0.005). Only EFL was associated independently with the development of PPCs (odds ratio 2.46 [95% CI, 1.28-4.80], p = 0.007). Conclusions: PPCs occurred frequently in this patient population undergoing cardiac surgery. PPCs were associated independently with the presence of EFL but not with driving pressure, total energy load, or mechanical power.