Lateral wall collapse from sleep endoscopy and airflow shape predicts hypoglossal nerve stimulation efficacy in obstructive sleep apnoea

Background Patient selection for hypoglossal nerve stimulation (HGNS) for obstructive sleep apnoea (OSA) requires assessment of pharyngeal site of collapse using drug-induced sleep endoscopy (DISE). The current study aims to address two key knowledge gaps. First, we prospectively confirm that, among HGNS candidates, reduced HGNS efficacy is associated with oropharyngeal lateral wall (OLW) collapse (Aim 1). Second, given DISE is a resource-intensive procedure and delays treatment, we evaluate whether a recently developed non-invasive method for identifying OLW collapse using airflow shapes is associated with reduced HGNS efficacy (Aim 2). Methods Patients who underwent DISE, HGNS implantation and follow-up sleep testing were included in Aim 1 (n=369) as part of an observational cohort study. For Aim 2, airflow data estimating OLW collapse probability were collected during DISE via a pneumotachograph (n=138; DISE Flow cohort) and from a home sleep test (HST) via nasal cannula for validation (n=46; HST cohort). Linear regression quantified associations between HGNS efficacy (percent reduction in apnoea–hypopnoea index (AHI)) and DISE-determined OLW collapse (Aim 1) or flow shape-determined OLW collapse (probability score per 2SD) (Aim 2), adjusting for baseline AHI. Results Compared to non-OLW collapse, DISE-determined OLW collapse reduced HGNS efficacy by −18.0% (95% CI −31.9– −6.2%). Increased flow shape-determined OLW collapse probability (Δ2SD) was associated with reduced HGNS efficacy in both DISE Flow (−24.8%, 95% CI −40.4– −11.7%) and HST (−22.7%, 95% CI −50.0– −2.6%) cohorts. Conclusion This study prospectively validates OLW collapse as a key factor in HGNS failure and shows that airflow-based identification of OLW collapse can effectively estimate HGNS efficacy, representing a significant advancement in patient selection for HGNS.