What makes the responder to upper airway stimulation in obstructive sleep apnea patients with positive airway pressure failure?

Treating obstructive sleep apnea (OSA) in patients with positive airway pressure (PAP) failure left many patients untreated or unhappy. Especially in moderate to severe cases with elevated body-mass index (BMI), therapy attempts with mandibular devices, tongue base or soft palate procedures turn out to be successful only in lower proportion of patients.