Changes in Upper Airway Anatomy and Apnea-Hypopnea Index in Patients with Obstructive Sleep Apnea Undergoing...

Background: Obstructive sleep apnea (OSA) is common in individuals with obesity, largely due to increased soft tissue causing upper airway narrowing. However, mechanisms of OSA improvement following weight loss are incompletely understood, particularly in Asian population, where craniofacial and soft tissue characteristics differ. This study aimed to evaluate changes in upper airway anatomy before and six months after bariatric surgery. Methods: We prospectively evaluated Indian obese patients with OSA undergoing bariatric surgery. Magnetic resonance imaging (MRI) and polysomnography were performed at baseline and six months post-surgery to assess volumetric changes in upper airway structures and the apnea-hypopnoea index (AHI), respectively. Correlations between MRI-derived structural changes, weight loss, and AHI were also analyzed. Results: Ten obese patients with OSA were included. Bariatric surgery resulted in significant reductions in body weight, body mass index (BMI), Epworth Sleepiness Scale score, and AHI (p < 0.05). MRI demonstrated a significant reduction in overall pharyngeal soft tissue volume, soft palate, pterygoid and parapharyngeal fat pad volume and tongue fat fraction. However, no significant changes were observed in total upper airway volume, retroglossal and retropalatal airway volume. Furthermore, no significant correlation was noted between changes in upper airway anatomy and post-operative changes in AHI or body weight. Conclusions: Bariatric surgery was associated with significant weight loss and improvement in OSA severity, accompanied by reduction in soft tissue volumes without significant increase in airway volume in this pilot study. These findings suggest a possible role of factors other than structural airway changes in the observed improvement in OSA following bariatric surgery.