Purpose: To explore the impact of H-uvulopalatopharyngoplasty (H-UPPP) in obstructive sleep apnea syndrome (OSAS) and gain insights into the potential mechanism underlying improvement by H-UPPP.
Methods: In a cohort of 11 OSAS patients, computational fluid dynamics (CFD) models of the upper airway were obtained using commercial software from computed tomography (CT) datasets before and after H-UPPP. Morphological and numerical parameters were respectively computed and compared during the peak tidal inspiratory flow. The correlations among polysomnography endpoints, airway dimensions, and pre- and post-operative airflow properties were analyzed with Spearman's rank correlation.
Results: The preoperative minimum cross-sectional area was significantly increased by 89.56% (p < .05), with a positive correlation to the apnea hypoapnea index (AHI) (r = 0.974). However, the capacity of all pharyngeal regions was not significantly altered (p > .05). Following H-UPPP, we observed a significant increase in pressure and reduction of velocity (p < .05) in the previously constricted areas. The change in pressure and velocity were significantly correlated with AHI (r = 0.922 and r = 0.946, respectively). In addition, the pressure drop in the constricted area, oropharynx, and hypopharynx were also significantly decreased (p < .05).
Conclusions: H-UPPP is capable of expanding the constricted region of the velopharynx and can decrease the airway resistance which will in turn decrease the workload necessary for breathing and facilitate inspiration.
Keywords: Airway resistance; Computer simulation; Obstructive sleep apnea syndrome; Pressure drop; Uvulopalatopharyngoplasty.
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