Implementation of a Wearable Ultrasound Device for the Overnight Monitoring of Tongue Base Deformation during Obstructive Sleep Apnea Events.

Obstructive sleep apnea (OSA) is a breathing disorder characterized by the repeated collapse of the pharyngeal airway during sleep. Previous studies have reported that tongue base deformation may be a major contributing factor. However, overnight monitoring of tongue motion in patients with OSA has previously been impracticable. We developed a wearable ultrasound device for prolonged recording during natural sleep of the changes in tongue base thickness (TBT) in patients with OSA. The maximum TBT was fed into a polysomnography system so that physiologic signals and TBT data were simultaneously monitored. Subject trials revealed that TBT increased significantly during snoring, hypopnea and apnea events during natural sleep in patients with OSA. Moreover, the data revealed that the location of the maximum TBT during normal breathing was significantly different compared with the location during obstructive respiratory events, which implies a posterior or inferior displacement of the tongue base during sleep apnea.