Flow-volume curves reflect pharyngeal airway abnormalities in sleep apnea syndrome.

Twenty-nine patients with disorders of excessive somnolence were evaluated with standard nocturnal polysomnography, fiberoptic laryngoscopy, and flow-volume curves. Twenty-two had evidence of obstructive sleep apnea (OSA) by polysomnography and most had abnormal flow-volume curves, supporting earlier observations. Three of 7 patients without obstructive sleep apnea also had abnormal curves. Fiberoptic nasopharyngoscopy was performed in the OSA group while awake to evaluate the upper airway. Sixteen patients of the OSA group demonstrated pharyngeal obstruction; 14 of those with visualized airway obstruction had flow-volume abnormalities. In the 6 patients of the OSA group with no significant visual obstruction, 5 had normal curves. The flow-volume curve appears to correlate with direct visual assessment of upper airway patency during wakefulness in those patients demonstrating obstruction during sleep.