Bioengineering Students Help Keep Peritoneal Dialysis Patients Out of the Hospital
The Bioengineering Senior Capstone Design course is a two-quarter, project-based course that asks teams of undergraduate bioengineering students to design and develop a health technology that addresses a real, unmet clinical need. It is open-ended and unlike any other challenge most students have ever tackled. “Going in, I was really nervous,” recalled 2018-19 student Alisha Birk. “Other than a structured assignment earlier in the course, I had never really built anything before; certainly nothing that potentially would solve a medical problem for real patients.”
Soon after the course gets underway, students receive vignettes that describe patients struggling with different healthcare issues. “We ranked the stories based on which problems we found most compelling, and then the course instructors used those rankings, plus our backgrounds outside of bioengineering, to assign us into teams,” explained Birk. With her background in cell biology, she was drawn to a vignette about a person with end-stage renal disease. She was assigned to work on that need area together with teammates Janelle Kaneda, who had interest in product design, and Mark Buckup, who had worked in electronics.
The next step for the team was to go back to the vignette, which deliberately touches on multiple issues, and begin researching the need area in order to isolate and define a specific problem to solve. “We got started by talking to our clinical mentor, Dr. Ha Tran, who is a pediatric nephrologist,” recalled Kaneda. “One of the first things she did was tell us about some of her patients who were on peritoneal dialysis.”
When patients have end-stage renal disease and their kidneys can no longer filter their blood adequately, peritoneal dialysis may be used to remove waste from the blood using the peritoneal lining of the abdomen as a filter. In the procedure, a catheter is inserted into the abdominal cavity to circulate a cleansing fluid that absorbs waste from the blood vessels in the abdominal lining. The fluid is then drawn out of the body and discarded. Unlike hemodialysis, which is most often performed in a clinical setting because the blood is filtered external to the body, peritoneal dialysis is typically done at home, providing greater lifestyle flexibility for patients. However, the procedure requires rigorous sterility measures to minimize the risk of peritonitis, a potentially serious infection of the abdominal lining that can result from bacteria entering the catheter.
The Need: Detecting Infection Early
In their initial meeting, Dr. Tran told the team about problems she saw in some patients, primarily teenage boys. “She said they don’t really think too much about their dialysis, so when they have early symptoms of peritonitis they just ignore them,” recalled Buckup. “By the time they go to the doctor the infection is pretty severe.” Unfortunately, peritonitis can cause scarring that requires the patient to switch to hemodialysis—limiting or eliminating their option for at-home treatment. And, if untreated, it can even be fatal if it spreads to the blood and other organs.
As the team dug into the scientific literature to learn more, they realized that it wasn’t just teenage boys who would fail to report symptoms of infection. “Peritoneal dialysis is also used on patients as young as one or two who might not even be able to verbalize their discomfort,” said Birk. “Learning about this got us thinking about ways to detect infection earlier and automatically, so that patients don’t have to think about it.”
The team learned that peritonitis is most often diagnosed through a white blood cell count. Birk explained, “When infection is suspected, patients provide a sample of their peritoneal dialysis effluent fluid to their doctor, which is the waste that’s extracted after dialysis. The doctors request bacterial culture and white blood cell count tests. If the white blood cell count is higher than 100, they have peritonitis.”
This information got the team thinking about building a chemical analysis device that patients could dip into their effluent fluid that would change color or otherwise clearly indicate the presence of an infection. “But we didn’t have the background in chemistry that was needed, and we weren’t sure how to prove a test like that worked without access to real effluent fluid initially,” said Kaneda. “Moreover, there were already companies that were looking at these types of markers and making dipstick tests, and we wanted to pursue routes that hadn’t been explored as well.”
A Physical Approach
Still, the team remained preoccupied with chemistry-based solutions until a course mentoring meeting with instructor David Camarillo (now associate professor of Bioengineering) and teaching assistant Christian Choe (graduate student in Bioengineering). “Fortunately for us, both of them have a physics background. They suggested we consider a physical, rather than a chemical approach, which opened up a whole new realm of possibilities,” recalled Buckup. “Sometimes you get so focused that you forget there’s a million ways to answer the same question. It was so helpful to have an outside perspective.”
The team decided to try spectrophotometry, a technique that can estimate the level of a chemical substance in solution based on the absorption of light of a certain wavelength as it passes through the solution. They started working on a device that could detect the presence of white blood cells in the effluent. Their idea was to connect it to the effluent drainage line so that the fluid could be automatically analyzed after each dialysis procedure.
The next challenge was figuring out how to implement the test in a way that would not create additional work for the patient. “The more we learned about peritoneal dialysis, the more we realized how burdensome the process is,” said Birk. “The patients have to set up a lot of equipment under very specific environmental conditions, and make sure it is all perfectly clean and sterile. And they have to go through this every night,” she described. “So we weren’t sure that they would want to take an extra step of connecting our device.”
Understanding the Patient Experience
To better understand the patient experience, the team connected with Dr. Ken Sutha, a colleague of Dr. Tran’s who, in addition to being a pediatric nephrologist, had been a peritoneal dialysis patient until undergoing a kidney transplant. Sutha introduced them to the parents of one of his patients, a two-year-old girl.
Although the family lived in Reno, Nevada, they traveled to Stanford monthly (a six hour drive each way) for a regular check-up for their daughter, and to renew orders to have boxes of fluids, connectors, and sterile tubing needed to perform the dialysis delivered to their home. On this visit, however, they had been airlifted to Stanford because of a peritonitis scare.
“Her line had become disconnected from her stomach and the parents were worried that, because there was a direct opening to her abdomen, she could have gotten an infection,” recalled Kaneda.
When the team described their solution to the parents, they responded enthusiastically. “They were really excited about having a sure way to determine whether or not their daughter had an infection,” said Buckup. “The idea of taking an extra minute to connect an extra piece of equipment was infinitely preferable to airlifting her every time they thought she might have an infection.”
National Recognition and Next Steps
The team moved forward with their project, advancing their solution into a working prototype. Near the end of the course, Dr. Tran suggested that they apply to the KidneyX Redesign Dialysis Phase I competition, which seeks solutions that can improve kidney failure management and patient quality of life. “She thought our device fit those parameters, so we wrote the application and submitted just before the deadline,” remembered Birk. “And then, in the spring, we learned that we had actually won a $75,000 prize!”
The award underscored the importance of the need and the promise of the solution they had developed. In August of 2019, the team spoke at the Innovations in Dialysis Symposium (IDEAS), and in November they were invited to present at the national KidneyWeek conference in Washington D.C.
“We had planned to lay the project aside and focus on pursuing our independent goals upon graduation,” said Kaneda. “But our recognition and connections with professionals in the field inspired us to keep pressing forward. Now that we have all graduated and are still pursuing our other goals, it’s not as easy to keep the project going as it was before. But we talk almost every day and are making steady progress.” Notably, the team has permission from the Stanford Institutional Review Board to test their device using patient effluent and to survey patients to get feedback on different device prototypes.
“The progress this team has made—and continues to make—is a testament to their hard work and creativity, as well as to the support and dedication of their clinical mentors, the BIOE141 course staff, and the Biodesign NEXT program” said Ross Venook, a lecturer in Bioengineering, associate director of engineering at Stanford Biodesign, and co-leader of the BIOE141 capstone course and team advisor. He continued, “I am impressed with how much the team has learned and grown, and I am excited about the potential for the team’s technology to help peritoneal dialysis patients.”
Reflecting on the experience, Birk encourages Capstone students to go into the course with an open mind, be willing to take their project wherever it leads, and try to be good teammates. “And while you’re in it, be fully in it and take every opportunity to learn that you can.”
All quotations are from interviews conducted by the authors unless otherwise cited.