Effect of Uvulopalatopharyngoplasty on Upper Airway Collapsibility in Obstructive Sleep Apnea

Previous investigators have demonstrated variable responses to uvulopalatopharyngoplasty (UPP) in patients with obstructive sleep apnea. We hypothesized that this variability is due to either (1) differences in baseline pharyngeal collapsibility preoperatively or (2) differences in magnitude of the decrease in pharyngeal collapsibility resulting from surgery. To determine the relationship between changes in collapsibility and the response to UPP surgery, we measured the upper airway critical pressure (Pcrit) before and after UPP in 13 patients with obstructive sleep apnea. During non-REM sleep, maximal inspiratory airflow (imax) was quantitated by varying the level of nasal pressure (PN), and Pcrit was determined by the level of PN below which imax ceased. A positive response to UPP was defined by a ⩾ 50% fall in non-REM disordered breathing rate (DBR). In the entire group, UPP resulted in significant decreases in DBR from 71.1 ± 22.4 to 44.7 ± 38.4 episodes/h (p = 0.025) and in Pcrit from 0.2 ± 2.4 to −3...