 The prevalence of sleep-disordered breathing in Republic of Korea is 27 and 16 in men and women aged 40-69 years. Up to 93 of women and 82 of men with obstructive sleep apnea OSA remain undiagnosed. Polysomnography, the gold standard, is time consuming and costly. Patients with undiagnosed OSA may experience obstructive episodes during procedures with conscious sedation. 