0541 Drug Induced Sleep Endoscopy: Is There a Difference in the Degree of Collapsibility at Different Sedation Levels?

Abstract

Introduction: Drug induced sleep endoscopy (DISE) has become the standard of care in many sleep centres, looking to identify sites of collapse in patients with obstructive sleep apnea (OSA) and snoring, so that the relevant surgery may be advocated. This study aims to compare the differences in the degree of collapse at various pre-identified anatomical sites at two different bispectral index (BIS) levels - light (BIS 70?80) and deeper (BIS 60?70) sedation. Method(s): This is a retrospective observational study design. 100 patients with obstructive sleep apnea of any severity, defined by an apnea-hypopnea index (AHI) of 5 or more on polysomnography, who are considering surgery at a tertiary hospital in Singapore, having failed or refused continuous positive airway therapy and other non-invasive treatment options, underwent DISE for pre-operative evaluation. The degrees of obstruction were evaluated at four different levels (velopharynx, oropharynx, tongue base, epiglottis) based on the VOTE classification, at two BIS levels - light (BIS 70?80) and deep (BIS 60?70) sedation. Result(s): Snoring is more prominent and there is greater degree of collapsibilty seen at all levels during deeper sedation (BIS 60?70), as opposed to light sedation (BIS 70?80). The anatomical site that is most prone to this increased collapsibility is the tongue base. Besides greater degree of collapsibility at a specific site, a greater number of sites are noted to be obstructed at deeper sedation levels as opposed to lighter levels. However this does not seem to correlate to the severity of OSA. Conclusion(s): DISE performed at sedation levels that are too light may not identify key areas of collapse that may play a role in OSA, and thus preclude successful surgical treatment of OSA.