A new swallowable electronic capsule about the size of a multivitamin could help diagnose sleep apnea and other sleep disorders.
The pill-shaped device works by using an accelerometer to measure a patient's breathing via lung expansion and heart rate from within the stomach. Besides its sensing apparatus, the capsule contains two small batteries to power it and a wireless antenna to transmit data to a laptop or other external device.
Sleep apnea is a condition in which breathing stops and starts during the night. It causes the brain to wake the person up, leading to poor-quality sleep. Diagnosis of such conditions typically requires patients to spend a night in a dedicated sleep lab, hooked up to a variety of uncomfortable sensors and monitor screens.
The new device, however, has the potential to make the process of screening for sleep disorders far less intrusive and even possible at home, in one's own bed. It could also be used to help monitor patients who are starting to get treated for sleep apnea—with a sleep mask or continuous positive airway pressure machine, for example—and ensure that the treatment is effective.
The study was undertaken by mechanical engineer and gastroenterologist professor Giovanni Traverso of the Massachusetts Institute of Technology and his colleagues. The full findings of the study were published in the journal Device.
Traverso told Newsweek: "Conventional laboratory and home sleep studies require the patient to be attached to many different sensors. As you can imagine, trying to sleep with all of this machinery can be challenging."
By contrast, he said, the "ingestible capsule just requires that the patient swallow the vitamin-sized pill. It's easy and unobtrusive and can accurately measure both respiratory rate and heart rate while the patient sleeps."
The study builds on previous work by the same team, which has developed a range of ingestible sensors that can both monitor vital signs and diagnose disorders of the gastrointestinal tract, such as inflammatory bowel diseases.
While these devices were tested while they were passing through the gastrointestinal tract, the new capsule—which was manufactured by the team's company, Celero Systems—is designed to work in the stomach, instead.
"The stomach generally offers some of the best signals, mainly because it's close to the heat and the lungs," Traverso said in a statement.
The researchers first tested the sensor in swine models, where they found it could accurately measure breathing and heart rates.
In a trial involving 10 human patients, the researchers were able to demonstrate that the capsule can successfully monitor vital signs. They also detected a sleep apnea episode that one of the subjects experienced during the study.
"What we were able to show is that, using the capsule, we could capture data that matched what the traditional transdermal sensors would capture," Traverso said.
He added: "We also observed that the capsule could detect apnea, and that was confirmed with standard monitoring systems that are available in the sleep lab."
The patients experience no ill effects from ingesting the capsule, the researchers reported, and in all cases the device passed harmlessly through the digestive tract.
The team confirmed this with X-ray imaging 14 days after each patient swallowed the capsule.
Previous work by the researchers, however, has suggested that objects of a similar size tend to move through the digestive tract in little more than a day.
Perhaps for the best, the capsule is designed to be single-use, although the team is working on adding a mechanism that will keep it from fitting through the pylorus, the opening that connects the stomach to the small intestine.
This would allow the device to stay in the stomach for up to a week, allowing for a more complete understanding of the degree of sleep apnea, and whether it is accompanied by paroxysmal atrial fibrillation, a type of irregular heartbeat that tends to occur less frequently than sleep apnea episodes do.
Besides helping to diagnose patients with sleep apnea, the new device could be used to monitor people who are at a high risk of an opioid overdose.
"We know that people who have had an overdose are at higher risk of recurrence," Traverso said. "Those individuals could be monitored more closely so that, in the event of another overdose, someone could help them."
In tests on swine, the team showed that the new sensor can detect the slowing down of breathing rate that results from a large dose of fentanyl, an opioid drug.
In future work, the researchers said, they plan to experiment with incorporating into the capsule an overdose reversal agent, such as nalmefene, that could be triggered to release when the patient's breathing rate has slowed down too much.
Traverso said: "Most people that die of an overdose die alone and unobserved. By acting autonomously, the Celero capsule will save lives of people who accidentally overdose when no third party is present to provide medication. We are very excited to bring this life-saving technology to as many people that need it, as soon as possible."
Dr. Sairam Parthasarathy told Newsweek: "Obstructive sleep apnea and other breathing disorders are common and are associated with adverse health outcomes such as heart attacks, strokes and even death due to such causes.
"However, many individuals with this condition often remain undiagnosed. The novel ingestible device that is being developed by researchers at MIT, Celero and West Virginia University could help diagnose such individuals in their own homes," said Parthasarathy, who is the director of the University of Arizona's Center for Sleep and Circadian Sciences and was not involved in the new study.
"This is an exciting development in the diagnostic arena that could help move the needle when it comes to diagnosing other breathing conditions, such as chronic obstructive pulmonary disease, as well," he said.
Wearable Sensors Listen to Bodily Sounds to Monitor Health
Another study published this week presents another monitoring system, although this one is designed to sit outside of the body.
Researchers from Northwestern University have developed soft, wearable sensors that stick to the skin and listen to sounds inside the body. From this, analysis can pick out the processes that cause these noises, from air moving in and out of the lungs to the beating of the heart and even the sound of food being processed.
The team demonstrated the potential of the devices on 15 premature babies with respiratory and intestinal motility disorders, as well as 55 adults, 20 of whom had chronic lung diseases.
The researchers showed that the sensors performed with clinical-grade accuracy and even offer new functionalities not previously available.
"A key advantage of this device is to be able to simultaneously listen and compare different regions of the lungs," said paper author and biomedical engineer professor John Rogers in a statement. "Simply put, it's like up to 13 highly trained doctors listening to different regions of the lungs simultaneously with their stethoscopes, and their minds are synced."
This, he said, allows the devices "to create a continuous and a dynamic assessment of the lung health that is translated into a movie on a real-life computer screen."
The full findings of the study were published in the journal Nature Medicine.
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About the writer
Ian Randall is Newsweek's Deputy Science Editor, based in Royston, U.K. His focus is reporting on science and health. He ... Read more
