Pathogenetic role of increased nasal resistance in obese patients with obstructive sleep apnea syndrome

Background: The role of increased nasal resistance in obstructive sleep apnea syndrome (OSAS) remains controversial. The aim of this study was to examine the pathogenetic role of nasal obstruction in obese patients with OSAS. Methods: Patients with OSAS (n = 125) at a university hospital were divided into three groups according to body mass index (BMI): nonobese (BMI < 25 kg/m²), mildly obese (25 kg/m² ≤ BMI < 30 kg/m ²), and obese (BMI ≥ 30 kg/m²). The subjects underwent nasopharyngoscopy, measurement of nasal resistance, and polysomnography. Results: We studied 42 nonobese, 47 mildly obese, and 36 obese patients with OSAS. Among the obese, but not the nonobese and mildly obese patients, we found significant correlations between the oxygen desaturation index (ODI) and bilateral nasal resistance (BNR; r = 0.412; p = 0.013), between the ODI and unilateral higher nasal resistance (UHNR; r = 0.413; p = 0.012), and between the apnea index and UHNR (r = 0.334; p = 0.046). Multiple regression analysis incorporating all patients showed that BMI (p < 0.001) and BNR (p = 0.033) were independently related to the ODI. Conclusion: In obese patients with OSAS, increased nasal resistance could play an important pathogenetic role in hypoxemic apnea.