Wearable ultrasound systems and software for assessment of obstructive sleep apnea

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Project Summary Sonosa Medical is developing a wearable ultrasound platform to enable advanced management of Obstructive sleep apnea (OSA) at an unprecedented precision and scale. OSA is a shockingly common condition that, along with side effects and comorbidities leads to a 10-15 year drop in life expectancy. When treated adequately, OSA is a manageable condition; however, existing management strategies are not adequate to meet the current and growing problem of OSA worldwide. Diagnosis of OSA is accomplished with a polysomnogram (PSG) or home sleep apnea test (HSAT) that uses multiple sensors to indirectly count obstructions, enabling an estimate of severity score: the apnea hypopnea index (AHI, number of events per hour). Though sensitive and specific as a diagnostic, the indirect nature of PSGs both in lab and at home provide little information on the cause of a patient’s obstructions. Despite phenotypic differences in OSA caused by numerous factors, treatment decisions follow a consistent path. Treatment of OSA begins with continuous positive airway pressure (CPAP), which uses a mask over the mouth and/or nose and a pump to create a pneumatic splint that holds the entire airway open. The broad effectiveness of CPAP is often negated by the intolerable discomfort created by the air pressure, mask, and noise leading to high non-compliance rates estimated at 35-60%. Once CPAP is rejected by patients, alternative treatments include oral appliances, surgery, implantable nerve stimulators, and pharmaceuticals. Though CPAP impacts the entire airway, most alternatives target specific tissues that contribute to obstructions such as the tongue base, soft palate, uvula, tonsils and adenoids, etc. Research shows that identification of these contributing tissues, termed the level or site of obstruction (SO), can help direct treatment and improve effectiveness. Indeed, newly proposed management strategies hinge on identifying phenotypic causes of OSA. OSA presents unique diagnostic challenges that have yet to be overcome by adaptation of existing techniques. To visualize obstructions, continuous monitoring on a sleeping patient must be achieved. Further, the scale of OSA requires a technology that is physically and financially accessible outside major academic hospitals. The information gathered with existing techniques such as Drug-induced sleep endoscopy(DISE), show promise but requires invasive, expensive procedures that only mimic sleep with sedation. Sonosa Medical has developed a wearable ultrasound system that is uniquely suited to the challenges presented by OSA. As a platform, wearable airway ultrasound can provide visibility of the airway in a small, comfortable device that can be used during natural sleep. Proposed in this work are steps to collect preliminary data to inform development of algorithms for processing ultrasound data needed to simplify the diagnostic interpretation of images and determination of SO.