Diagnosing sleep disorders such as sleep apnea typically requires a patient to spend the night in a sleep laboratory, connected to a variety of sensors and monitors. Researchers at MIT, Celero Systems and West Virginia University hope to make this process less intrusive, using an ingestible capsule they developed that can monitor vital signs from the patient’s gastrointestinal tract.
The capsule, which is about the size of a multivitamin, uses an accelerometer to measure the patient’s breathing rate and heart rate. In addition to diagnosing sleep apnea, the device could also be useful in detecting opioid overdoses in high-risk people, the researchers say.
“This is an exciting intervention to help people get diagnosed and then receive the appropriate treatment if they have obstructive sleep apnea,” says Giovanni Traverso, associate professor of mechanical engineering at MIT and gastroenterologist at the Brigham and Women’s Hospital. “The device also has the potential to quickly detect changes in respiratory status, whether due to opioids or other conditions that could be monitored, such as asthma or chronic obstructive pulmonary disease (COPD). ).”
In a study of 10 human volunteers, researchers showed that the capsule could be used to monitor vital signs and detect episodes of sleep apnea, which occurs when the patient repeatedly stops and starts breathing during his sleep. Patients showed no adverse effects from the capsule, which passed safely through the digestive tract.
Traverso is one of the lead authors of the study, along with Robert Langer, professor at the MIT Institute and member of MIT’s Koch Institute for Integrative Cancer Research; Victor Finomore, director of the Center for Research in Human Performance and Applied Neuroscience at West Virginia University School of Medicine; and Ali Rezai, director of the Rockefeller Neuroscience Institute at West Virginia University School of Medicine. The article appears today in the journal Device.
Vital sign measurements
Over the past decade, Traverso and Langer have developed a range of ingestible sensors that could be used to monitor vital signs and diagnose disorders of the gastrointestinal tract, such as gastrointestinal slowdown And inflammatory bowel diseases.
This new study focused on measuring vital signs, using a capsule developed by Celero Systems that includes an accelerometer that detects slight movements generated by the beating of the heart and the expansion of the lungs. The capsule also contains two small batteries and a wireless antenna that transmits data to an external device such as a laptop.
When tested on an animal model, researchers found that this capsule could accurately measure respiratory rate and heart rate. In one experiment, they showed that the sensor could detect depression in respiratory rate resulting from a high dose of the opioid drug fentanyl.
Based on these results, the researchers decided to further test the capsule in a clinical trial in West Virginia University Rockefeller Neuroscience Institute. Ten patients enrolled in the study were monitored using the ingestible capsule, and these patients were also connected to the sensors typically used to monitor sleep, so the researchers could compare measurements from the two types of sensors.
The researchers found that their ingestible sensor was able to accurately measure both respiratory rate and heart rate, and it also detected an episode of sleep apnea experienced by one of the patients.
“What we were able to show was that by using the capsule, we could capture data that matched what traditional transdermal sensors would capture,” says Traverso. “We also observed that the capsule could detect apnea, and this was confirmed by standard monitoring systems available in the sleep laboratory.”
In this study, researchers monitored signals from the capsule while it was in the stomach, but during a previous studythey showed that vital signs can also be measured from other parts of the gastrointestinal tract.
“The stomach usually offers some of the best signals, mainly because it’s close to the heart and lungs, but we know we can detect them elsewhere as well,” says Traverso.
None of the patients reported any discomfort or damage caused by the capsule. X-ray imaging performed 14 days after ingestion of the capsules revealed that all had passed through the patients’ bodies. The research team’s previous work has shown that objects of similar size typically move through the digestive tract in just over a day.
The researchers envision that this type of sensor could be used to diagnose sleep apnea in a less intrusive manner than the skin sensors currently in use. It could also be used to monitor patients when they begin treatment for apnea, to ensure treatments are effective.
Célero Systemsa company founded by Traverso, Langer, Jeremy Ruskin, a professor of medicine at Harvard Medical School, and Benjamin Pless, now the company’s CEO, is currently working on sensors that could be used to detect sleep apnea or opioid overdose.
“We know that people who have overdosed are at higher risk of recurrence, so these people could be monitored more closely so that if they overdose again, someone can help them,” Traverso says.
In future work, researchers hope to incorporate an overdose reversal agent such as nalmefene into the device, so that drug release is triggered when the person’s breathing rate slows or stops. They are also working on strategies to extend the time the capsules can stay in the stomach.
The research was funded by the Karl van Tassel Career Chair, the MIT Department of Mechanical Engineering and Celero Systems.
The paper’s authors also include Pless, James Mahoney, Justin Kupec, Robert Stansbury, Daniel Bacher, Shannon Schuetz and Alison Hayward.