The use of practice guidelines by the American Society of Anesthesiologists for the identification of surgical patients at high risk of sleep apnea

Abstract

American Society of Anesthesiologists (ASA) has introduced a simple tool to assess the perioperative risk of surgery/anesthesia in patients with obstructive sleep apnea (OSA). We compared the surgical outcomes in patients at high risk of OSA with the matched controls. This was a case–control study conducted on 3593 surgical patients receiving a general anesthesia at a single institution. On the basis of a preoperative OSA scoring system using the ASA checklist, patients were classified as high-risk OSA (HR-OSA) or low-risk OSA (LR-OSA) groups. Apnea/hypopnea index of >5 h−1 during a formal preoperative sleep study was used to confirm or rule out the diagnosis of OSA. Receiver operating characteristic curves were plotted to determine the predictive values as well as sensitivity and specificity of the ASA tool in predicting HR-OSA. The HR-OSA group was matched with the patients in LR-OSA using the propensity scoring and logistic regression. Patients were analyzed for premorbid conditions, intraoperative course and postoperative events using cross tabulation, logistic regression model and paired t test. The development of a composite respiratory complication in the postoperative period was considered as the primary end point. The ASA risk tool was found to have 95.1% sensitivity and 52.2% specificity. At a prevalence of 10%, the negative predictive value was 98.5%. Of the 3593 patients, 306 were identified as HR-OSA. The HR-OSA group was found to have a higher incidence of hypertension and diabetes preoperatively when compared with LR-OSA. Postoperatively, the HR-OSA group had higher incidence of hypoxia, reintubation, postoperative use of continuous positive airway pressure and a longer stay in the recovery room. The ASA checklist offers a highly sensitive tool to identify the patients at a higher risk of OSA during the perioperative period. Patients at HR-OSA have a higher incidence of adverse events in the postoperative period when compared with those with LR-OSA.