Scientists have developed a prototype wearable device that uses sensors and an injector to detect and reverse an opioid overdose, somewhat similar to how an insulin pump acts to protect against diabetes.

A research team at the University of Washington has developed a wearable device that monitors breathing patterns to detect and administer an antidote to counteract opioid toxicity. The system is attached to the abdomen to monitor when a person stops breathing and moving, at which point it will automatically inject a life-saving antidote called naloxone.

According to the paper published in Scientific Reports, the results demonstrate the proof-of-concept for an automated system capable of administering care in the event of an unwitnessed overdose.

“The opioid epidemic has become worse during the pandemic and has continued to be a major public health crisis,” said lead author Justin Chan, a UW doctoral student in the Paul G. Allen School of Computer Science & Engineering. “We have created algorithms that run on a wearable injector to detect when the wearer stops breathing and automatically inject naloxone.”

Previous studies have established that cessation in breathing (known as an apnea event) signals a potentially fatal opioid overdose. Although naloxone can reverse opioid toxicity, it needs to be administered quickly, which is challenging when the user is alone — this is where the new device comes in, working as a ‘closed-loop’ — a fully automatic system triggered by feedback needing no human intervention.

In this case, the closed-loop system, which has received regulatory approval in the United States, has an algorithm that triggers the injector in the presence of apnea lasting more than 10 seconds. Based on a relatively simple design, the solution comprises a pair of accelerometers placed on the abdomen to measure respiration, a microcontroller to track the halt of motion associated with breathing, and an automated injection system to administer the antidote. The device also transmits breathing rates to a nearby smartphone via Bluetooth, adding an extra layer of safety.

“A closed-loop naloxone injector system has the potential to complement existing evidence-based harm reduction strategies and, in the absence of bystanders, help make opioid toxicity events functionally witnessed and in turn more likely to be successfully resuscitated,” the scientists wrote in the study.

To test the device, the scientists conducted a clinical trial involving 25 volunteers in a supervised injection facility in Vancouver, Canada, and another parallel trial in a hospital among participants who manifested signs of apnea by holding their breath. The researchers said these trials were crucial to developing breathing algorithms involving real-world, opioid-induced changes.

At the Vancouver site, the research team noted that the device could accurately track respiration rates among people with an opioid-use disorder and was also able to detect opioid-induced apnea.

The tests measured breathing patterns only to develop the respiratory algorithm and did not involve the injection of naloxone due to the risk involving potentially fatal overdoses. Therefore, researchers only administered the antidote in the hospital study involving healthy human volunteers who did not take opioids.

In this second study, 20 healthy participants simulated overdose events by holding their breath for over 10 seconds to mimic apnea. Results showed that it took 16.9 to 25.9 seconds from the cessation of breath for the injector to activate- the team verified the level of naloxone in the participant’s bloodstream before and after the injection. They noted that there were no adverse reactions across all subjects in the study.

Based on these results, the scientists believe the system could deliver the antidote into the blood, showing its potential to reverse opioid overdoses. But, further studies are needed to assess the safety and portability of the device over more extended periods.