The last few years have seen a number of mobile apps emerge that monitor your breath for signs of various diseases.  It’s part of a fascinating trend, the latest addition to which is a new app developed by researchers at the University of Washington, which aims to monitor your breathing for sign of a drug overdose.

The work, which was documented in a recently published paper, has resulted in an app, called Second Chance, which the team claim is able to accurately spot overdose-related symptoms 90% of the time.

“The idea is that people can use the app during opioid use so that if they overdose, the phone can potentially connect them to a friend or emergency services to provide naloxone,” the researchers explain. “Here we show that we have created an algorithm for a smartphone that is capable of detecting overdoses by monitoring how someone’s breathing changes before and after opioid use.”

Measuring sound waves

The app is pretty ingenious, and measures sound waves as they travel from the smartphone to the individual’s chest to gauge the breathing patterns of the user.  An obvious first thing to look out for is when the user stops breathing entirely, but another valuable marker is when the breathing rate drops to seven breaths per minute.  This is the usual cutoff point used in hospitals to test the health of the patient.

Being able to do this whilst the user is moving about presents an additional challenge, but also an opportunity, as it allows the phone to measure for other things, such as whether the user’s head slumps.

The researchers developed the app after monitoring people at the Insite supervised injection facility in Vancouver, Canada, which is a legal supervised consumption site.  Volunteers were monitors on their chest to measure their breathing rates as they injected.

“We asked participants to prepare their drugs like they normally would, but then we monitored them for a minute pre-injection so the algorithm could get a baseline value for their breathing rate,” the authors explain. “After we got a baseline, we continued monitoring during the injection and then for five minutes afterward, because that’s the window when overdose symptoms occur.”

The app was then tested on a group of just over 90 people, half of whom had a breathing rate of less than seven breaths per minute, and half of whom had stopped breathing for a significant period.  The app was able to accurately identify problems in 90% of these events.

Detecting overdoses

With Insite being a monitored and controlled environment, it perhaps goes without saying that actual overdoses are few and far between, so the team had to take another strategy to get training data for such events.  They decided to work with anesthesiology teams to simulate overdoses to then allow the app to monitor how people behaved during the event, and at what point they stop breathing.

“When patients undergo anesthesia, they experience much of the same physiology that people experience when they’re having an overdose,” the team explain. “Nothing happens when people experience this event in the operating room because they’re receiving oxygen and they are under the care of an anesthesiology team. But this is a unique environment to capture difficult-to-reproduce data to help further refine the algorithms for what it looks like when someone has an acute overdose.”

During testing, the app was able to correctly predict an overdose 19 out of 20 times, with the one incorrect prediction involving a patient whose breathing rate was higher than the algorithm’s threshold.

Whilst at the moment the app is only passively monitoring users, the ultimate aim is to have a service that is able to interact with the user via the alarm that requests a response from the user before escalating things to emergency services.

The team have applied for FDA approval and have developed a spinout company from the University of Washington, called Souapplnd Life Science, through which they aim to bring it to market as a commercial product.

“We’re experiencing an unprecedented epidemic of deaths from opioid use, and it’s unfortunate because these overdoses are completely reversible phenomena if they’re detected in time,” the team conclude.  “The goal of this project is to try to connect people who are often experiencing overdoses alone to known therapies that can save their lives. We hope that by keeping people safer, they can eventually access long-term treatment.”