“…These included patient demographics and comorbidities such as age, sex, BMI (22), ASA physical status classification, the Charlson Comorbidity Index, the Score for Prediction of Postoperative Respiratory Complications (23), and smoking status (24). Furthermore, the model was adjusted for procedural duration, surgical service, work relative value units (based on Current Procedural Terminology [CPT] codes) as a surrogate for surgical complexity, total vasopressor dose, the total amount of administered crystalloid and colloid fluids (25), total nondepolarizing neuromuscular blocking agent dose (expressed as the median effective dose required to achieve a 95% reduction in maximal twitch response from baseline) (26)(27)(28), dose of long-and short-acting intraoperative opioids, neostigmine dose (26), number of packed RBC units administered (29), age-adjusted minimal alveolar concentration of inhalational anesthetics and nitrous oxide, airway device, use of sugammadex (19,30,31), use of succinylcholine, and Fio 2 . Lastly, we adjusted for the year in which the procedure was performed to account for potential trends over time.…”