There is a critical need for safe and effective treatment options for persistent obstructive sleep apnea (OSA) in patients with Hypotonic Upper Airway Obstruction (HUAO). HUAO encompass conditions such as cerebral palsy, hypoxic encephalopathy, syndromic tone anomalies, Trisomy 21 or Down Syndrome, and neuromuscular disorders, and typically share a similar pattern of multisite upper airway collapse. OSA is characterized by recurrent episodes of partial or complete upper airway obstruction during sleep with associated arousals and/ or oxygen desaturations. In contrast to the incidence of OSA among children which is between 1-5%, there is a significantly higher prevalence of OSA among children with hypotonic conditions, cerebral palsy, and Trisomy 21/Down Syndrome. Of hypotonic patients undergoing polysomnography (PSG) for symptoms of sleep disordered breathing, 25% had moderate OSA, and 56.3% had severe OSA. Thus, not only are patients more likely to have OSA, but it is likely to be much more severe. Despite the obvious upper airway collapse seen in most of these patients, there is a paucity of data in literature, both on prevalence and severity of OSA in these conditions, but also on treatment efficacy particularly with regards to multi-level obstruction and moreover, with duration of treatment efficacy. Currently available treatment options, ranging from palliative care to tracheostomy, often fail to fully meet the needs of these patients. Our multidisciplinary team has developed a dramatically effective non-surgical nasopharyngeal airway stent that has demonstrated good tolerability in hypotonic patients. Treatment of OSA in HUAO presents an extremely difficult challenge, in part due to diffuse multilevel obstruction with lack of muscular airway tone. This renders many surgical approaches, other than tracheostomy, likely to fail. Although surgical options such as adenotonsillectomy are common, most children with HUAO have residual OSA after the procedure, due to residual anatomic and physiological abnormalities. This often necessitates attempted treatment with Positive Airway Pressure (PAP) or consideration for tracheostomy. However, the rate of adherence with PAP in typically developing children can be low, and even lower in those with hypotonic conditions. Moreover, inability to remove a mask during an emesis can pose a suffocation risk. Tracheostomy carries associated risks for morbidity and mortality, a substantial addition of care needs, family burden, nursing demands, and hundreds of thousands of dollars of medical costs. Our multidisciplinary team, led by Otolaryngology – Head and Neck Surgery, Sleep Medicine, and Engineering, has designed, developed, and successfully piloted a self-supported nasopharyngeal airway (ssNPA) device that bypasses challenging, diffuse, multilevel upper airway obstruction. The device has demonstrated initial safety and preliminary efficacy in a pilot group of patients, severe OSA. The Start-up phase (R61) of the grant will test an enhanced version of the device for acceptability and tolerability. Critically, insertion, adherence, and compliance protocols will be optimized for preparation of the R33 phase. The R33 phase will assess a powered cohort looking at PSG and quality of life outcomes.