 Previous studies reported that STOP-Bang questionnaire predicted cardiopulmonary events during advanced endoscopic procedures such as endoscopic retrograde cholangiopancreatography ERCP and endoscopic ultrasound. However, there have been no studies regarding the risk for sedation-related cardiopulmonary events in patients with undiagnosed OSA undergoing bronchoscopy. Thus, we aimed to evaluate the prevalence of high-risk patients for OSA by a screening questionnaire, and to determine whether the questionnaire could predict patients who are at risk for cardiopulmonary events during bronchoscopy with conscious sedation. 