Expiratory Snoring Predicts Obstructive Pulmonary Disease in Patients with Sleep-disordered Breathing

Sleep-disordered breathing and chronic obstructive pulmonary disease are two common conditions that may present concomitantly. The effects of chronic obstructive pulmonary disease on the polysomnographic manifestation of sleep-disordered breathing have not been studied. We hypothesized that the presence of airflow obstruction could be predicted by the presence of expiratory upper airway narrowing during sleep in patients with sleep-disordered breathing. Ninety-three patients with sleep-disordered breathing (19 men; age, 51.6 yr; body mass index, 40.1 kg/m(2); apnea-hypopnea index, 37.4 events/h) were observed. Every patient had an in-lab polysomnography study and complete pulmonary function tests. Sleep and respiratory events were scored using American Academy of Sleep Medicine recommended scoring criteria. Expiratory snoring events were identified on polysomnography using microphone sensor and/or pressure flow sensor in each patient. The FEV1/FVC ratio less than 70 was used to define the presence of airflow obstruction. The proportion analysis demonstrated that patients with expiratory snoring have 11 times higher odds of having evidence of lower airway obstruction, defined as FEV1/FVC less than 70 (odds ratio [OR], 11.03; P