Smartphone App Helps Monitor Lung Function

SpiroSmart app (Shwetak Patel, University of Washington)

Engineers at University of Washington in Seattle created a prototype smartphone app that can monitor lung functioning of patients with asthma and cystic fibrosis. A team from Washington’s electrical engineering department and Seattle Children’s Hospital presented the results of a test of the app earlier this month at the ACM International Conference on Ubiquitous Computing.

The app, called SpiroSmart, performs the functions of a spirometer, a device that measures air volume and flow rate in the lungs. Spirometers are usually found in doctors’ offices, but some home systems have appeared recently. Lung patients blow hard and fast as they can into a tube with a small turbine that measures the speed of the flow, until they are out of breath. The spirometer measurements then indicate if airways are narrowed or filled with mucous.

Engineering graduate students Eric Larson in electrical engineering and Mayank Goel in computer science, working in the lab of engineering professor Shwetak Patel, devised a model of a person’s trachea and vocal tract built as a system of tubes and pipes. SpiroSmart uses the smartphone’s microphone to capture the sound wave frequencies from the patient blowing on the smart phone. Based on that model, the software then analyzes the sound wave frequencies to detect breathing function irregularities in the patient’s pipes.

“There are resonances that occur in the signal that tells you about how much flow is going through the trachea and the vocal tract,” says Patel, “and that’s precisely the quantity that a clinician needs to know.”

The research team tested the app installed on an Apple iPhone model 4S with 52 mainly healthy volunteers. The tests show SpiroSmart came within 5.1 percent of a commercial portable spirometer that costs thousands of dollars. Normal variation in spirometer measurements is about 3 percent, say the researchers.

The Washington engineers received a grant from the Coulter Foundation that supports further development and clinical trials of SpiroSmart, as well as prepare for submission to the U.S. Food and Drug Administration for approval. The university’s technology transfer office is also helping the researchers bring their invention to market.

The following short video shows the SpiroSmart at work.

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