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Lung Function App Service Expanded to Any Phone

Cell phone with SpiroCall message

SpiroCall provides spirometry tests with early cell phones and landlines. (University of Washington)

3 May 2016. A computer science lab extended the abilities of its smartphone app that measures lung function to a call-in service for any phone in the world. The team led by engineering and computer science professor Shwetak Patel at University of Washington will discuss the new service at the ACM Computer-Human Interaction (CHI) 2016 conference that begins on 7 May in San Jose, California.

Patel’s UbiComp lab in Seattle developed in 2012 a smartphone app known as SpiroSmart that measures the flow rate and volume of lungs when inhaling and exhaling, functions usually tested with a spinometry instrument in a clinic and some home devices. Spinometers are used to diagnose lung diseases, such as asthma and chronic obstructive pulmonary disease, or COPD, as well as monitor lung functions over time in people with these disorders.

As reported in Science & Enterprise, Patel’s team built the SpiroSmart app to capture sound waves from a person blowing into the smartphone’s microphone. The app uploads the recorded sound file to a server, where a model of a human trachea and vocal tract is used to analyze the sound waves. Software on the server then detects breathing irregularities, with a report sent back to the app. Since 2012, Patel and colleagues tested SpiroSmart with more than 4,000 individuals, and clinical trials of the app are underway in the U.S., India, and Bangladesh.

While the SpiroSmart app makes it possible to expand spirometry to more people than before, the smartphone requirement still leaves out many individuals in low-resource regions or those without smartphones. To fill those gaps, the lab devised a call-in service known as SpiroCall that allows individuals to measure their lung functioning with regular voice telephone lines and early cell phone models. Reports are then sent back as text messages to phones on cellular networks.

SpiroCall had to overcome lower audio quality when a person breaths into a telephone handset or cell phone, then carried over voice telephone line or cellular frequency. To meet this challenge, the UbiComp team of Patel and doctoral students Mayank Goel and Elliot Saba rewrote its analytical algorithms, first breaking down the breathing flow rate signals, then calculating the regression lines into a single median estimate of lung functioning.

The researchers also encountered wide variation in types of telephones and the distance between the caller’s mouth and handset that influenced audio quality. In addition, people with severe lung problems could not generate breathing sounds loud enough to be captured consistently by the call-in system. To overcome these problems, the team designed a simple plastic whistle, which they produced on a 3-D printer, modeled after a similar whistle created in 1954 that changes pitch when breathing flow rates change.

Patel and colleagues recruited 50 volunteers to test SpiroCall, of which 16 had asthma or other lung conditions. The test recorded and analyzed lung functions with voice telephone calls on smartphones, earlier-model cellphones, and landline handsets. The calls were captured on voicemail, then uploaded to the SpiroCall server. The volunteers also tested the system with and without the plastic whistle, and took measurements of their lung functions with clinical spirometers.

The results show lung function measurements made with SpiroCall, both with and without the plastic whistle, varied on average 6.2 percent from clinical spirometers, within standard margins of error for those devices. Using the whistle, however, reduced the number of false positive readings and made the estimation models easier to generalize across different types of phones.

In the following video, Goel and Saba tell more about SpiroCall.

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