The objective was to evaluate the prevalence of patients at a high risk of having OSA by using a screening questionnaire and to investigate whether the questionnaire can predict patients who are at risk of cardiopulmonary events occurring during a bronchoscopy under sedation. We prospectively enrolled consecutive adult patients who underwent flexible bronchoscopies under moderate sedation. The snoring, tiredness, observed apnea, high blood pressure-body mass index, age, neck circumference and gender (STOP-Bang) questionnaire was used to identify patients at a high (score ≥ 3 of 8) or low risk (score < 3 of 8) of having OSA. The cardiopulmonary events included hypoxemia and hypotension. Multivariable logistic regression was performed with variables selected by the least absolute shrinkage and selection operator. The prevalence of a STOP-Bang score of ≥ 3 was 67.2% (195/290), and 36.9% (107/290) experienced cardiopulmonary events. The multivariable analysis adjusting for chronic obstructive pulmonary disease, chronic kidney disease, baseline SpO₂, and procedure time revealed that a STOP-Bang score of ≥ 3 was significantly associated with cardiopulmonary events in a subgroup of patients without a history of cerebrovascular disease (adjusted odds ratio, 1.94; 95% confidence interval, 1.06-3.54). The STOP-Bang questionnaire can predict cardiopulmonary events occurring during this procedure.Trial registration: NCT03325153.