Upper airway collapsibility evaluated by negative expiratory pressure test in severe obstructive sleep apnea

V) and expiratory volume were measured in the first 0.2 s (V0.2) of the negative expiratory pressure test. RESULTS: D _ V (%) and V0.2 (%) values were statistically different between normal and OSA subjects. OSA patients showed a greater decrease in flow than normal subjects. In addition, severely OSA patients exhaled during the first 0.2 s of the negative expiratory pressure application was an average of only 11.2% of the inspired volume compared to 34.2% for the normal subjects. Analysis of the receiver operating characteristics showed that V0.2 (%) and D _ V (%) could accurately identify severe OSA in subjects with sensitivities of 95.8% and 91.7%, respectively, and specificities of 95.8% and 91.7%, respectively. CONCLUSIONS: V0.2 (%) and D _ V (%) are highly accurate parameters for detecting severe OSA. The pharyngeal collapsibility measurement, which uses negative expiratory pressure during wakefulness, is predictive of collapsibility during sleep.