A new app transforms smartphones into high-tech instruments for measuring lung capacity. SpiroSmart uses the phone's microphone to listen for subtle abnormalities in an exhalation, creating data that's good enough for doctors to monitor patients' conditions without requiring an office visit.

The software's creators hope to make life a little easier for people with respiratory conditions that may benefit from more frequent lung measurements, including those with chronic asthma or chronic obstructive pulmonary disease.

People with lung conditions may need to measure and record their lung capacities using a device called a spirometer as often as a few times a week, said Shwetak Patel, an engineer at the University of Washington in Seattle who led the research. "It depends on the condition," he told TechNewsDaily. "It's definitely enough that [measuring and recording] would be pretty cumbersome."

But there aren't any spirometers that balance affordability with rigorous measurements, Patel said. At-home meters that record data that's high-quality enough for doctors to use can cost up to $4,000 and are about the size of a laptop, according to a paper Patel and his research team presented Sept. 6 at an Association for Computing Machinery-hosted conference in Pittsburgh.

"Those very portable, cheap devices are still not available yet," he said. He and his team are hoping their app, SpiroSmart, is the answer.

SprioSmart doesn't need any extra smartphone attachments or sensors, which helps keep it low-cost, Patel said. Following the on-screen instructions, users hold their smartphone about arm's-length away and breathe in deeply. Then, they exhale as quickly and forcefully as they can. As they bluster away, the app records the noise it hears through the phone's microphone.

Afterward, the app searches the recorded exhalation for sounds associated with reduced lung capacity. "We're looking at very subtle signals in that sound that actually tell you a lot about the amount of constriction that one may have," Patel said.

To learn what sounds to look for, Patel and his colleagues gathered and analyzed exhalation recordings from people with different lung conditions over two years. They also created a computer model of the human lung system to help them predict how different lung constrictions would translate into different sounds. Using a combination of its real-life and computer-model data, SpiroSmart is able to analyze exhalation noises and create the same curved graph that clinical spirometers record, and which doctors study to help them diagnose patients.

In his recent Association for Computing Machinery study, Patel tested SpiroSmart in 52 study volunteers, including 39 people who didn't report that they any lung conditions and 13 people who had conditions ranging from mild asthma to a collapsed lung. He found that SpiroSmart's measurements had a 5.1% error rate. The American Thoracic Society requires spirometers to have an error rate between 5 and 7%, Patel said.

Lung disease specialists at the University of Washington are now running a pilot study in hopes of earning U.S. Food and Drug Administration approval for SpiroSmart.

If SpiroSmart is approved, Patel envisions that lung specialists will be able to write prescriptions for the app. Patients would receive a special code that allows them to download SpiroSmart from app stores. The app could directly share patients' spirometry graphs with their doctors, so patients don't have to remember to keep a journal of their measurements. In addition, a version of the app that's not connected with a doctor's office could be available without a prescription. "For patients who are just interested, for themselves," Patel said.

source:mashable