Expiratory flow limitation as a risk factor for pulmonary complications after major abdominal surgery

BACKGROUND: Postoperative pulmonary complications are major causes of postoperative morbidity and mortality. Although several risk factors have been associated with postoperative pulmonary complications, they are not consistent between studies and, even in those studies in which these factors were identified, the predictive power is low. We hypothesized that postoperative pulmonary complications would correlate with the presence of intraoperative expiratory flow limitation. METHODS: Candidates for this prospective observational study were patients undergoing general anesthesia for major abdominal surgery. Preoperative data collection included age, body mass index, American Society of Anesthesiologists class, smoking and dyspnea history, and room air Po 2. Expiratory flow limitation was assessed intraoperatively using the positive end-expiratory pressure test. Postoperative data collection included the incidence of postoperative pulmonary complications. RESULTS: Of the 330 patients we enrolled, 31% exhibited expiratory flow limitation. On univariate analysis, patients with expiratory flow limitation were more likely to have postoperative pneumonia (5% vs 0%, P <.001) and acute respiratory failure (11% vs 1%, P <.001) and a longer length of hospital stay (7 vs 9 days, P <.01). Multivariate analysis identified that expiratory flow limitation increased the risk of developing postoperative pulmonary complications by >50% (risk ratio, 2.7; 95% confidence interval, 1.7-4.2). Age and Medical Research Council dyspnea score were also significant multivariate risk factors for pulmonary complications. CONCLUSIONS: Our results show that intraoperative expiratory flow limitation correlates with that of postoperative pulmonary complication after major abdominal surgery. Further work is needed to better understand the relevance of expiratory flow limitation on postoperative pulmonary outcomes.