1308 Refractory Residual AHI with Improvement on a Custom Oral Appliance on BiPAP

Abstract Introduction Obstructive sleep apnea (OSA) is well documented as a leading cause of chronic intermittent hypoxia and sleep fragmentation, contributing to increased morbidity and mortality. Positive airway pressure (PAP) remains the gold-standard treatment for moderate to severe OSA, whereas mandibular advancement devices (MADs) are typically reserved for mild to moderate disease or for patients who are unable to tolerate PAP. The combined use of PAP and MAD therapy, however, remains understudied. We present a case in which combination therapy was used to achieve further reduction in apnea burden. Report of case(s) An 88-year-old man with severe OSA, class I obesity (BMI 33.1), and hypertension underwent diagnostic polysomnography in 2013 that demonstrated an apnea hypopnea index (AHI) of 12 events/hr, a respiratory disturbance index (RDI) of 37 events/hr, and an oxygen saturation nadir of 86%. Thus, BiPAP of 20/10 cmH2O after a titration study was performed. Over the following years, despite interventions including adherence optimization, patient education, limiting of central nervous system depressants and weight loss. He persisted in having a residual AHI of 12.7 (AI 10.4, HI 2.3) of mostly obstructed events. Given his inability to tolerate BiPAP, a trial of a Biblock mandibular advancement device used concurrently with his therapy was initiated. After seven nights of combination MAD plus BiPAP at 20/10 cm H₂O, his AHI improved to 4.1 events/hr with notable symptomatic improvement. Conclusion This case highlights the potential benefit of combining MAD and PAP therapy to further reduce AHI and improve symptoms in select patients with OSA. While promising, long term data on combination therapy remain limited and further studies are needed to evaluate its efficacy. Current evidence suggests that MADs are most effective in patients with oral-anatomic phenotypes rather than nasal resistance phenotypes, with little difference between monoblock and titratable devices. Drug induced sleep endoscopy (DISE) has been proposed as a tool to directly assess sites of upper airway obstruction and guide therapy, but its role in identifying candidates for combination therapy is still evolving. Additional research is needed to develop clear criteria and phenotyping methods to identify patients who may derive optimal benefit from combined MAD-PAP therapy. Support (if any)