Relationship of Upper Airway Collapse with Severity of Sleep Apnoea and Sleepiness.

Introduction : Obstructive sleep apnoea (OSA) is characterized by repeated episodes of upper airway collapse. A review of literature shows limited and conflicting data regarding impact of upper pharyngeal collapse on severity of OSA and degree of sleepiness. Objective : To evaluate the association of the number of levels and degree of upper airway collapse and severity of OSA. Methods : This is a retrospective study including all patients with OSA over a two-year period. Data regarding neck circumference (NC), body mass index (BMI), nasopharyngolaryngoscopy with Muller's manoeuvre, Epworth sleepiness scale (ESS) questionnaire and a full night polysomnography were collected. Correlation of the number of sites involved and degree of collapse at each site (velum, lateral pharyngeal wall- Level I, base of tongue - Level II and epiglottis - Level III) with BMI, NC, AHI and ESS were assessed. Results : Of the 144 patients, 98% had collapse at Level I. 80% of patients had multisegmental collapse with 30% having collapse at all three levels. The number of levels and the severity of collapse did not have a proportionate effect on the AHI and ESS and were not directly dependent on the BMI. However, changes in NC had a significant effect on the severity of collapse. Conclusion : Severity of OSA and degree of sleepiness were not directly dependent on the severity and the number of levels of collapse. Since majority of the patients had multi segmental collapse, the study highlights the importance of careful assessment of all levels to tailor management strategies for optimum patient management.