Abnormal inspiratory flow-volume curves in patients with sleep-disordered breathing

Although flow-volume curves are valuable in detecting extrathoracic airway obstruction, their role in testing patients with sleep-disordered breathingis undefined. To determine whether patients with sleep-disordered breathinghave abnormal flow-volume curves consistent with variable extrathoracic obstruction, 60 subjects referred with suspected sleep disordersprospectively underwent spirometryand assessment of flow-volume curves. These tests were interpreted independent of the outcome of polysomnography. Fourteen of 35 subjects (40%) with sleep-disordered breathinghad abnormal flow-volume curves consistent with variable extrathoracic airway obstruction, and 2 of 25 (8%) with no breathingdisorder had extrathoracic obstruction (p < 0.02). The presence of extrathoracic airway obstructionin subjects with mixed or obstructive sleep apneadid not correlate with age, the presence of snoring, excessive daytime hypersomnolence, obesity, or the severity of sleep apnea. Abnormal flow-volume curves were found m...