We’ve gotten used to electronic devices that collect data about our bodies. Fitness trackers measure exercise and calorie counts. Smart watches take your pulse (and can even send it to a friend). Continuous glucose monitors test a diabetic’s blood sugar and send warnings about impending highs or lows. Gadgets like this that we wear on the outside of our bodies seemed like science fiction just a few years ago, so it’s not a great stretch of the imagination to start thinking about measuring things from the inside of the body too.
Gastroenterologists at the University of Chicago Medicine are experimenting with an electronic “smart pill” that takes measurements about temperature, pressure and pH inside the digestive tract. A patient swallows it like a normal pill, and as it passes through the body, it transmits this data wirelessly to a receiver that can be worn on the belt or carried in their pocket or handbag nearby. Physicians can then download and analyze the data to troubleshoot digestive issues, track how quickly food is moving through certain parts of the system and monitor medications.
“It’s a very expensive thing that you flush down the toilet when you’re done,” joked Adam Mikolajczyk, MD, a gastroenterology fellow at UChicago who recently published a study about using smart pills to measure pH and transit time through the gut.
So far, the FDA has only approved the use of the smart pills (literally marketed as the SmartPill by Given Imaging, a medical device manufacturer in Israel) for measuring transit time through the colon and spotting suspected gastroparesis, a condition that reduces the ability of the stomach to empty its contents.
Mikolajczyk was interested in studying pH levels in the digestive system of patients with ulcerative colitis. Some drugs for ulcerative colitis are delivered in pH-dependent coating, so it doesn’t dissolve unless it reaches a certain pH. If a patient’s gut was very acidic, for example, or had wide fluctuations in pH levels, they may not be getting the treatment they need. Older research from 20-25 years ago showed conflicting data: some studies said these patients had a more acidic colon (lower pH) and some said it was more alkaline (higher pH).
Mikolajczyk and his mentor David Rubin, MD, the Section Chief of Section Chief, Gastroenterology, Hepatology and Nutrition at UChicago, wanted to study pH values in these patients using more modern methods. But the first order of business was establishing a baseline. What does the pH profile of a healthy patient look like? And does the SmartPill offer a reliable way to measure it?
In a study published in the journal Clinical and Translational Gastroenterology this July, they recruited healthy volunteers who swallowed two SmartPills, 24 hours apart, to see if they provided consistent measurements of pH throughout the different parts of the digestive system, plus the total time they took to pass through the system.
Rubin noted that this was the first such study to look more closely at the data the pill transmits. “It provides clinicians and researchers with much needed information about the performance characteristics of the device—in other words, how reliable it is in an individual patient,” he said.
The subjects each ate a special “SmartBar” with standardized ingredients created by the company to wash it down, followed by a period of fasting to make sure everyone was eating the same diet. The wireless receiver also had an “event button” to track the timing of meals and bowel movements, mainly as a way to capture when the pill, well, exited the system.
In a nutshell, the pills did the job, providing reliable data on pH throughout the system on both tries. Currently, the pills don’t have the technology to provide pinpoint data on their location, but Mikolajczyk and Rubin were able to infer that from known parameters of temperature, pressure and pH of certain sections of the gut. He could also pinpoint when the pills left the body by sudden drops in pressure and temperature (think cold toilet bowls), although he noted that many of the study subjects were keen on using the event button and confirming this themselves, visually.
“It was like pattern recognition,” Mikolajczyk said. “As I was reading this data, I would look for certain changes and see that it’s left the stomach and now it’s in the small bowel, then it left the small bowel and it’s in the colon. That way it gives you a sense of where it is in the GI tract.”
It was a small study, but it shows that so far the SmartPill is a reliable tool to take basic measurements from the digestive tract. As it gets better location tracking abilities, its usefulness will expand beyond these basic applications, and give physicians more powerful tools to measure the body from within.