1314 Case of Transient Hypoventilation After Hypoglossal Nerve Stimulator Implantation

Abstract Introduction Down Syndrome is a chromosomal disorder with a high incidence of obstructive sleep apnea (OSA). Treatment of OSA in this population can be challenging due to limited surgical interventions and tolerance to positive airway pressure therapy. The use of hypoglossal nerve stimulation (HGNS) was recently approved for the treatment of OSA in pediatric patients with Down Syndrome 13 years of age and older. HGNS treats OSA by stimulating the hypoglossal nerve which leads to the contraction of the genioglossus muscle, reducing obstruction of the upper airway. Known adverse effects of HGNS therapy include discomfort from nerve stimulation, temporary weakness of the tongue, dry mouth, device malfunction, infection, and hematoma. This case report describes emergence of temporary hypoventilation in a patient with Down syndrome after HGNS implantation. Report of case(s) Patient is a 19-year-old male with Down Syndrome, intellectual disability, hypothyroidism, allergic rhinitis, congenital heart disease, ADHD, scoliosis, and OSA. Treatment history for his OSA include use of supplemental oxygen, continuous positive airway pressure therapy (CPAP), and surgical interventions (adenotonsillectomy, laryngeal cleft closure, and a lingual tonsillectomy). Due to poor CPAP adherence, patient underwent HGNS implantation. Both the baseline polysomnogram (PSG) prior to implantation and activation PSG after implantation showed slightly elevated transcutaneous pCO2 (TcCO2) (maximum 56.2 mmHg) levels, without hypoventilation. Two months after activation a fine-tuning study showed resolution of OSA (AHI 3.7/hr) but with hypoventilation (TcCO2 values greater than 50 mmHg for 37.3% of the total sleep time). This suggests that the hypoventilation began after implantation of the HGNS and was not caused by underlying OSA. The hypoventilation was confirmed with elevated serum bicarbonate levels (34). Repeat fine tuning PSGs show that the hypoventilation improved with time. 5 months post implant, the max TcCO2 was 53.6 mmHg with levels > 50 mmHg for 21.6% TST. At 11 months post implant, max level was 51.7 mmHg with levels > 50 mmHg for only 2.6% of total time. Conclusion After HGNS implantation, our patient had temporary, self-resolving hypoventilation which was not associated with untreated obstructive sleep apnea. Support (if any)