Pill-sized device monitors vital signs from the gut

US scientists have developed an ingestible device that can safely monitor vital signs like breathing and heart rate from inside of us, providing patients with easier access to health care without the need to go to hospital. The so-called vitals-monitoring pill, or VM pill, has been described in the journal Device.

Unlike implantable devices such as pacemakers, ingestible devices are easy to use and do not require a surgical procedure. For example, doctors have in recent years been using pill-sized ingestible cameras to conduct colonoscopies, a procedure traditionally conducted in a hospital setting.

“The idea of using an ingestible device is that a physician can prescribe these capsules, and all the patient needs to do is to swallow it,” said co-author Benjamin Pless, founder of the medical device developer Celero Systems. “People are accustomed to taking pills, and costs of using ingestible devices are much more affordable than performing traditional medical procedures.”

The VM pill works by monitoring the small vibrations of the body associated with breathing and the beating heart. The pill can detect if a person stops breathing from the inside of the digestive tract.

The VM pill shown in a clear gel capsule for ease of visualisation of internal components. Image credit: Ben Pless.

To test out the VM pill, the team placed the device in the stomach of pigs, which were put under anaesthesia. Researchers then administered the pigs with a dose of fentanyl that caused the pig to stop breathing, which is what happens during fentanyl overdose in humans. The device measured the pig’s breathing rate in real time and alerted the researchers, who were able to reverse the overdose.

The team also tested the device in humans for the first time by giving the VM pill to those being evaluated for sleep apnoea, a disorder in which breathing repeatedly stops and starts during sleep. Many people with the condition remain undiagnosed, in part because diagnosing the condition involves admitting people to a sleep laboratory where they are hooked up to external devices to monitor their vital signs during sleep.

“Given our interest in opioid safety, it came to our attention that sleep apnoea has a lot of the same symptoms as opioid-induced respiratory depression,” Pless said.

Researchers gave the VM pill to 10 patients with sleep apnoea at West Virginia University (WVU). The device was able to detect when the participants’ breathing stopped and to monitor respiration rate with an accuracy of 92.7%. Compared with external vital monitoring machines, the pill can monitor heart rate with an accuracy of at least 96%. The trial also showed the device is safe, and all participants excreted the device in the few days after the experiment.

“The accuracy and correlation of these recordings were excellent compared to the clinical gold standard studies we performed in our sleep laboratories,” said co-author Ali Rezai, a neuroscientist at the WVU Rockefeller Neuroscience Institute. “The ability to remotely monitor critical vital signals from patients without wires, leads or need of medical technicians opens the door for monitoring patients in their natural environments versus the clinic or the hospital setting.”

First author Giovanni Traverso, an associate professor at the Massachusetts Institute of Technology, said the current version of the VM pill passes through the body in about a day, but the device could be modified in the future to allow it to stay longer for long-term monitoring. The researchers also hope to upgrade the device so it can deliver drugs to reverse conditions like opioid overdose automatically once it detects symptoms.

Top image: Ali Rezai holds the Celero VM pill. Image credit: WVU Rockefeller Neuroscience Institute.