Intraoperative Factors Associated With Mechanical Ventilation Duration Following Aortic Surgery

Objectives: Prolonged postoperative mechanical ventilation is a common complication after major aortic surgery. The relationship between prolonged ventilation and intraoperative variables influenced by anesthesiologists, such as ventilation practices, fluid administration, and blood pressure control during major aortic surgery is unknown. We sought to identify perioperative factors, including intraoperative physiologic and anesthesia-related variables, which are associated with ventilation duration following aortic surgery. Design: Single-center retrospective observational study. Setting: A tertiary, high-volume cardiac surgery referral center. Participants: Adult patients undergoing major aortic surgery requiring cardiopulmonary bypass (CPB). Interventions: None (retrospective observational study). Measurements and Main Results: The primary outcome was the duration of postoperative ventilation (hours). Mixed-effects regression was performed to identify factors associated with the primary outcome. Among the 647 patients included in this study, the median of postoperative mechanical ventilation duration was 9.0 (IQR 6.0, 14.4) hours, with 73 (11.3%) of patients receiving mechanical ventilation for more than 24 hours. Variables significantly associated with the outcome were increases in pre- to post-CPB driving pressure (β = 4.23; 95% CI [0.08, 8.39]; p = 0.04), reduction in pre- to post-CPB end-tidal carbon dioxide partial pressure (β = –5.12; 95% CI [–8.85, –1.39]; p < 0.001), and normalized transfusion volumes (β = 11.14; 95% CI [4.36, 17.91]; p < 0.001). Mechanical power was not associated with postoperative ventilation duration (β = –2.29; 95% CI [–6.48, 1.90]; p = 0.52). Conclusions: Patients undergoing major aortic surgery are at risk for prolonged mechanical ventilation. Transfusion volume and pre- to post-CPB changes in driving pressures and end-tidal carbon dioxide are significantly associated with postoperative ventilation duration. Intraoperative mechanical ventilator power is not a significant predictor of mechanical ventilation duration after major aortic surgery. These variables are potentially modifiable by anesthesiologists and may be future therapeutic targets.