Assessment of Site, Degree and Pattern of Airway Obstruction in Patients with Moderate to Severe Obstructive Sleep Apnoea (OSA) Using Drug Induced Sleep Endoscopy (DISE)and Its Association with Awake Fibreoptic Evaluation and Polysomnography Parameters.

Accurate assessment of site of obstruction in Obstructive Sleep Apnoea (OSA) is key to its effective management, especially the surgical intervention. Currently, Drug induced sleep endoscopy (DISE) is widely used to assess the obstruction during sleep as assessing during physiologic sleep is impractical and cumbersome. To assess the site, pattern and degree of airway obstruction in patients with moderate to severe obstructive sleep apnoea using DISE and to find a co-relation of DISE findings with awake fibreoptic assessment and severity of OSA. 41 adult patients (29 males, 12 females, mean AHI 40.58 ± 16.94, mean age 54 ± 9.15 years underwent awake fibreoptic nasal endoscopy in the outpatient department and propofol induced DISE in the main operation theatre. The site/s, degree and pattern of obstruction were recorded as per VOTE and Fujita classification. Velum was the commonest site of collapse followed by oropharynx, base of tongue and epiglottis. All had multilevel collapse with velum, oropharynx and base of tongue being the most common combination. At velum, base of tongue and epiglottis, antero-posterior pattern of collapse was commonest and at oropharynx lateral pattern of collapse was the commonest. We found no difference in the site, pattern or severity of collapse between the moderate and severe group though there was a tendency of epiglottis collapse being present more frequently in severe OSA. Awake fibreoptic endoscopic evaluation was able to assess the collapse at level of velum with higher sensitivity but with poor specificity. There was high chances of missing a hypopharyngeal collapse with fibreoptic endoscopic evaluation.