The Pharyngeal Resistance Index—A Promising Diagnostic Tool in <scp>OSA</scp>

This study investigates the newly developed pharyngeal resistance index derived from computational fluid dynamics analysis of the upper airway in patients with obstructive sleep apnea. The aim was to evaluate this index as a diagnostic and severity assessment tool by comparing it with the apnea-hypopnea index before and after maxillomandibular advancement surgery. A retrospective single-center study was conducted at the Department of Oral and Maxillofacial Surgery, Charité-Universitätsmedizin Berlin, including 16 patients with obstructive sleep apnea who underwent maxillomandibular advancement between November 2019 and June 2023. Each patient received polysomnography and cone beam computed tomography preoperatively and at least three months postoperatively following a standardised protocol. The apnea-hypopnea index and pharyngeal resistance index were statistically compared. The mean apnea-hypopnea index decreased from 23.42 (SD = 22.53) preoperatively to 4.32 (SD = 5.0) postoperatively, a mean reduction of 81.55%. Mean pharyngeal resistance index decreased from 0.96 (SD = 0.81) preoperatively to 0.17 (SD = 0.22) postoperatively, representing an 82.29% reduction. Wilcoxon signed-rank tests confirmed significant postoperative improvements for both indices (p < 0.01). Spearman analysis revealed no significant correlation between both indices, either preoperatively (ρ = 0.130, p = 0.633) or postoperatively (ρ = 0.159, p = 0.556). Class-based comparison demonstrated improved agreement postoperatively, with most discrepancies limited to within ±1 class. Although no direct correlation was found, the pharyngeal resistance index demonstrated significant postoperative improvement and enhanced class-level agreement with the apnea-hypopnea index, supporting its future role as a supplementary diagnostic and predictive tool in obstructive sleep apnea management.