Today, patients with chronic lung conditions such as cystic fibrosis or asthma can't easily monitor how their airways are doing. Instead, they have to go to the doctor's office and blow into a special device called a spirometer as hard and fast as they can.
So for the past two-plus years, grad students at the University of Washington in Seattle have been working to develop an app that can measure lung function just as accurately but without the need for additional hardware. (Existing apps either require hardware or are for entertainment purposes only.)
In other words, they've been trying to turn a smartphone into a spirometer.
Now, the electrical engineering and computer science researchers are unveiling their SpiroSmart app, which they tested on 52 "mostly healthy" volunteers, and which came within 5.1 percent of a commercial, portable spirometer that costs thousands of dollars. (They say that the effort a patient exerts to exhale during the test results in an unavoidable variation of about 3 percent.)
Basically, the researchers modeled the human trachea and vocal tract as a system of tubes that could replace a traditional spirometer, and used the microphone on an iPhone 4S to analyze the sound wave frequencies that result when someone blows into the phone in order to deduce how much air is moving through those tubes.
"By analyzing lip reverberation we are capable of monitoring pulmonary ailments such as asthma, chronic obstructive pulmonary disease, and cystic fibrosis," they write on the SpiroSmart website.
"There are resonances that occur in the signal that tells you about how much flow is going through the trachea and the vocal tract, and that's precisely the quantity that a clinician needs to know," said lead researcher Shwetak Patel, a UW assistant professor of computer science and engineering and of electrical engineering, in a school news release.
The team has received a grant from the Coulter Foundation to do more clinical testing with patients who span more ages and range from having healthy lungs to chronic lung conditions. They're also seeking FDA approval and looking into how to make the lung testing procedure part of a simple but fun game on the phone that users won't mind playing regularly.