Hypoglossal Nerve Stimulation Outcomes and Upper Airway Collapsibility During DISE

Introduction: Obstructive sleep apnea (OSA) is largely due to structural and neuromuscular alterations in pharyngeal collapsibility (critical pressure, Pcrit). Prior studies indicate that the therapeutic effects of hypoglossal nerve stimulation (HGNS) are attributed to reductions in Pcrit. We hypothesized that Pcrit is a potential predictor of (HGNS) outcomes in OSA.

Methods: Drug-included sleep endoscopy with positive airway pressure titration (DISE-PAP) was used to determine upper airway (UA) collapsibility at high and low levels of neuromuscular activity (Pcrit and PhOP, respectively). Patients were selected within a narrow PhOP range to control for passive anatomic determinants. The difference between these two metrics (PhOP - Pcrit ) provided an estimate of UA neuromuscular reactivity. HGNS responses were assessed by comparing preoperative and postoperative apnea-hypopnea indices (AHI). Neuromuscular reactivity and AHI reduction were then correlated.

Results: 27 middle-aged (64.6+-8.7 yrs), male (74%), obese (29.7+-4.2 kg/m2), and with moderate-severe OSA (AHI 30.1+-14.7 events/hour) had a mean AHI reduction after HGNS activation of 15.0+-14.5 events/hr. (p < 0.01). Pcrit and PhOP were 0.4+-2.5 cmH2O and 7.0+-2.1 cmH2O, respectively. PhOP-Pcrit differential was 6.5+-2.7 cmH2O, and correlated with less AHI reduction after HGNS activation, although not yet statistically significant (r=0.25, p = 0.210).

Conclusions: Our findings suggest that PhOP-Pcrit difference during DISE may predict HGNS outcomes and suggest that this therapy is most effective in patients with diminished intrinsic neuromotor tone. We aim to explore this relationship in a larger sample size to further understand predictors for HGNS outcomes.