New smartphone app can detect sleep apnea

A new app that uses a smartphone to wirelessly test for sleep apnea from the comfort of a person's bedroom has been developed by researchers, including those of Indian-origin.
Unlike other home sleep apnea tests in use today, ApneaApp uses inaudible sound waves emanating from the phone's speakers to track breathing patterns without needing special equipment or sensors attached to the body.
In a clinical study, ApneaApp captured sleep apnea events as accurately as a hospital polysomnography test 98 per cent of the time.
Researchers believe the app could be available to consumers in the next year or two.
"Right now we don't have enough sleep clinics, sleep laboratories and sleep specialists in the country to address all the sleep apnea that is out there," said co-author Dr Nathaniel F Watson, professor of neurology and co-director of the University of Washington Medicine Sleep Centre.

"These initial results are impressive and suggest that ApneaApp has the potential to be a simple, noninvasive way for the average person to identify sleep apnea events at home and hopefully seek treatment," said Watson.

To determine if a person is experiencing sleep apnea events, ApneaApp transforms an Android smartphone phone into an active sonar system that tracks tiny changes in a person's breathing movements.
The phone's speaker sends out inaudible sound waves, which bounce off a sleeping person's body and are picked back by the phone's microphone.
"It's similar to the way bats navigate," said Rajalakshmi Nandakumar, lead author and a doctoral candidate in the UW's department of computer science and engineering.

"They send out sound signals that hit a target, and when those signals bounce back they know something is there," said Nandakumar.
Because the sound waves are at a frequency adults can't hear, the app easily screens out audible background noise from people talking, cars honking or a bedroom fan.
"Right now phones have sensing capabilities that we don't fully appreciate," said co-author Shyam Gollakota, assistant professor of computer science and engineering.
The clinical study tested ApneaApp on 37 patients undergoing sleep studies at Harborview Medical Center because of apnea concerns.
Researchers put a smartphone on a corner of the bed during the overnight sleep study.

During nearly 300 hours of testing, the app tracked various respiratory events including central apnea, obstructive apnea and hypopnea with between 95 and 99 per cent accuracy, compared to intensive polysomnography.
ApneaApp correctly classified 32 out of 37 patients in the clinical study.
Tests in a home bedroom setting showed ApneaApp works efficiently at distances of up to 3 feet, in any sleeping position and even when the person is under a blanket.