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Background: Postoperative pulmonary complications (PPC) are associated with higher healthcare costs, prolonged hospital stays, and increased morbidity and mortality than that of other postoperative complications. Many studies have demonstrated that prolonged operative duration is associated with increased postoperative morbidity and mortality. To our knowledge, the direct impact of operative duration on PPCs has not been specifically analyzed. We hypothesize that longer operative times are independently associated with an increased risk of PPCs in patients undergoing complex gastrointestinal procedures.

Methods: We queried American College of Surgeons National Surgical Quality Improvement Program 2009 Participant User File for patients who underwent elective open colectomy, hepatectomy, or pancreatectomy. For this study, PPC was defined as pneumonia, prolonged mechanical ventilation greater than 48 hours, and unplanned reintubation. Patients both with and without PPCs were evaluated for operative duration, length of hospital stay, and 30-day mortality. The impact of operative duration on the risk of PPC was evaluated using logistic regression models with PPC occurrence as an outcome and operative time (in hours) as the predictor. A model was also run controlling for preoperative functional status and American Society of Anesthesiologist (ASA) class to account for differences in preoperative patient acuity.

Results: 8620 cases (5523 colectomies, 915 hepatectomies, and 2182 pancreatectomies) were reviewed. 456 patients (5.3%) experienced at least one PPC. For operations less than 480 minutes, each 60-minute increase in operative time was associated with a 13% increased risk of PPC (OR 1.133; 95% CI, 1.077-1.192). For operations exceeding 480 minutes, each additional 60 minutes of operative time beyond 8 hours was associated with a 30% increased risk of PPC (OR 1.296; 95% CI, 1.143-1.470). Controlling for differences in operative procedures did not affect regression modeling. Thirty-day mortality occurred in 54 (0.7%) patients without PPC, whereas 72 patients (15.7%) with one or more PPC died postoperatively. Overall, patients with one or more PPC were 28 times more likely to die than those who did not have a PPC (OR 28.3, p<0.0001). The average length of stay for patients with at least one PPC was nearly three times as long as those without PPCs (20.08 vs. 7.43 days, respectively; p<0.0001).

Conclusions: Operative duration is independently associated with increased risk of PPC in patients undergoing complex gastrointestinal procedures, thus indirectly leading to increased postoperative mortality and longer hospital stays.