Acoustic reflection for nasal airway measurement in patients with obstructive sleep apnea-hypopnea syndrome

Study Objective: To measure nasal dimensions and explore relationships between these and patients' use of continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). Design: Prospective single-blind study. Setting: A tertiary-care, sleep disorders referral center. Patients: Sixty OSAHS patients (52 men, mean age 51 years, body mass index (BMI) 36.1 +/- 9.4 kg /m(2)). Measurements: After in-vitro validation, acoustic reflection was used to measure the nasal minimal cross-sectional area (MCSA), mean area, and volume in OSAHS patients receiving CPAP treatment. Variables from sleep studies included the apnea-hypopnea index (AHI), titration pressure, and CPAP use (hours per night) after 3 months. Median MCSA was used to categorize subjects into small and large MCSA groups. Correlation and regression analyses were conducted to investigate the relationship between results of polysomnography and nasal acoustic reflection. Results: At baseline the small and large MCSA groups were not different (P >.05) in BMI, age, mask type, or previous nasal stuffiness, but there were more women in the smaller MCSA group (P =.02). CPAP use was significantly lower in the small MCSA group (P =.007), but apnea-hypopnea index and titration pressure were indistinguishable between the 2 groups. Furthermore, CPAP use correlated significantly and positively with MCSA (r = 0.34, P =.008), mean area (r = 0,27, P =.04), and volume (r = 0.28, P =.03). Step-wise multiple regression models revealed that MCSA was a predictor of the CPAP compliance (R-2 = 0.16, P =.002), and MCSA (P =.001) and age (P =.04) were predictive factors of CPAP compliance (R-2 = 0.22). Nasal dimensions were not related to subjective nasal stuffiness. Conclusions: CPAP use in patients with smaller nasal passages was lower than in those with larger passages. Objective measurement of nasal dimension may be more reliable than subjective self-report of nasal symptoms in identifying patients with OSAHS who might struggle with CPAP therapy.