Characterizing post-extubation negative pressure pulmonary edema in the operating room—a retrospective matched case-control study

Abstract Background Post-extubation negative pressure pulmonary edema (NPPE) is an uncommon but important anesthesia-related emergency presenting with acute respiratory distress and hypoxemia after removal of airway devices. This study investigated the incidence and associated risk factors for post-extubation NPPE during emergence. Methods This retrospective, matched case-control study was conducted by reviewing the post-anesthesia records in Tzu Chi General Hospital, Taiwan. Patients reported of having acute hypoxemia (SpO2 < 92%) shortly after the removal of the endotracheal tube or supraglottic airway, associating with radiographic evidence of pulmonary edema and/or pink frothy sputum, were identified as definite NPPE cases. The potential risk factors were compared with the matched controls, who were randomly selected from the same database. Results A total of 85,561 patients received general anesthesia with airway instrumentation during the 8.5-year study period. A total of 16 patients were identified as definite cases of NPPE. Compared with the matched controls (n = 131), males, active smokers, emergency operation, endotracheal intubation, use of desflurane, and prolonged operation time carried significantly higher risks of developing NPPE (P < 0.05). Multivariate logistic regression analysis illustrated that active smoking (AOR 7.66, 95% CI 1.67–35.3; P = 0.009) and endotracheal intubation (AOR 10.87, 95% CI 1.23–100; P = 0.03) were the two most significant independent variables of post-extubation NPPE. Conclusion We present the first clinical comparative study demonstrating that the overall incidence of NPPE immediately after extubation in the operating room is 0.019%. Our results highlight that active smokers and patients receiving endotracheal intubation general anesthesia are associated with significantly higher risks of developing NPPE following extubation in the operating room.