Upper airway anatomical balance contributes to optimal continuous positive airway pressure for Japanese patients with obstructive sleep apnea syndrome

Abstract

Background: The aim of this study was to examine whether the upper airway anatomical balance, as reflected by tongue size relative to maxillomandibular size, is related to optimal nasal continuous positive airway pressure (PnCPAP). Methods: Sixty-six male Japanese obstructive sleep apnea syndrome (OSAS) patients (median apnea-hypopnea index [AHI] = 33.9 episodes/h [10th/90th percentile = 19.5/59.9], median body mass index [BMI] = 25.1 kg/m2 [10th/90th percentile = 21.2/30.4]) were recruited. All patients underwent standard polysomnography (PSG), and PnCPAP was determined by nasal continuous positive airway pressure (nCPAP) titration. The anatomical balance was defined as the tongue area (TG) divided by the lower face cage (LFC) measured on cephalometry. A predictive equation of PnCPAP was created using demographic, polysomnographic, and cephalometric variables. Results: Significant correlations were found between PnCPAP and descriptive variables, including BMI, AHI, lowest SpO2, distance from the anterosuperior point of the hyoid bone to the mandibular plane (MP-H), and TG/LFC. Stepwise multiple regression analysis revealed that AHI and TG/LFC were independent predictors of PnCPAP. The predictive equation was: PnCPAP = 1.000 + 0.043 x AHI + 9.699 x TG / LFC, which accounted for 28.0% of the total variance in PnCPAP (R 2 = 0.280, p < 0.01). Conclusions: Anatomical balance of upper airway in addition to the severity of OSAS is an important contributing factor for PnCPAP in Japanese OSAS patients.