Mechanics of the pharynx in patients with obstructive sleep apnea.

We describe a novel method for evaluating the location, closing pressure and compliance of collapsing segments in the passive pharyngeal airway of patients with OSA. Observation on 16 patients with obstructive sleep apnea, revealed that the site of collapse in 6 patients was exclusively in the nasopharynx, whereas oro- and hypo-pharyngeal sites were localized in others. We speculate that a segment with a high closing pressure predisposes to airway narrowing during normal breathing during sleep. We also speculate that compliance of the segment interacts with regional muscle force and intra-luminal pressure to determine airway size.