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Brady Hauser and Adam Bauer working
April 27, 2021

Pediatric physicians tap biomedical engineering students to design lumbar puncture model

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Performing a spinal tap requires precision, particularly when the patient is a newborn. During their residencies, physicians training in pediatrics practice on infant-sized models and observe a live procedure up close. Then it’s their turn—and when that time comes, they’ll feel for the relevant anatomical landmarks, insert a needle and guide it into the spine’s epidural space.

“There is a very big difference between palpating landmarks on a rubber model with plastic bones and actually completing it on a live neonate,” says Dr. Brady Hauser, a resident in the Department of Pediatrics at the University of Wisconsin-Madison.

In an effort to create another training tool for lumbar punctures on infants, Hauser turned to the Department of Biomedical Engineering’s undergraduate design program (BME Design), which pairs student teams with clients from industry and academia and challenges them to create prototypes of medical devices and technology that address practical, unmet needs.

Megan Baier positioning a plastic spine
Biomedical engineering student Megan Baier positions a plastic spine before the group pours the gel into the model.

Hauser’s task for the students: create a newborn-sized training simulator that would allow aspiring doctors to practice lumbar punctures under the guidance of ultrasound imaging. While healthcare providers are increasingly using ultrasound technology to inform procedures, Hauser notes that no commercially available products allow clinicians to train on ultrasound-guided lumbar punctures.

During the 2020-21 school year, a team of undergraduate biomedical engineering students has created several prototypes, honing their research and design skills while learning to adapt to roadblocks caused by the COVID-19 pandemic.

“It is a constant dynamic process,” says Noah Pollard, one of two juniors who have worked on the project all year, with seven other students rotating through as part of their design experience.

While Pollard and his groupmates have spent the spring 2021 semester developing several slightly different prototypes, the core of their device is a 3D-printed, newborn-sized spine surrounding a silicone tube containing water to mimic cerebrospinal fluid, all of which is encased in a gel composed of a liquid PVC polymer mixed with mineral oil.

The students endured hard lessons in flexibility, adaptability and patience while getting started on the project during the fall semester. Pandemic-related shipping delays held up the arrival of the liquid polymer, one the group identified as an ideal material after reading about it in a research paper. Then they discovered that creating a gel with the correct look and feel wasn’t simple, with air bubbles and clumping chalk—which they used as a contrast agent to sharpen the ultrasound images—requiring reevaluation.

And, of course, they had to contend with the broader challenge of creating a physical prototype during a time of remote learning and limited lab access. Team leader Seth Gehrke says the full group never met in person, instead relying on weekly Zoom meetings and gatherings of two to three for hands-on assignments. In that sense, the pandemic forced the students to sharpen their communication—overcommunicating became the norm, Pollard says—while trying out new methods of work. Gehrke, for example, 3D-printed the model spine entirely remotely through the College of Engineering’s makerspace.

More recently, the group improved the consistency of the gel and added a key feature (when the user inserts a needle into the correct location, liquid releases to simulate spinal fluid flow that results from a successful lumbar puncture) based on feedback from clients Hauser and Adam Bauer, an assistant professor in the Department of Pediatrics.

Pollard and Gehrke say that with more time—a possibility, if the project continues into the 2021-22 academic year—they’d like to use open-source CT scans and 3D printing to add in more of the key anatomical landmarks that physicians look for when performing the procedure. In the meantime, Hauser is pleased with the students’ progress.

“Within six months, we went from absolutely nothing that we know of and nothing on the market to now they’re producing several prototypes that are testable and that we’re fine tuning,” he says.

That experience of taking on a novel challenge and creating a possible solution is at the core of the BME Design curriculum.

“It definitely gives you critical thinking and problem-solving skills, just skills required for engineering,” says Gehrke. “How can we accomplish this? And then you try to go actually accomplish it. It’s definitely beneficial to put your skills from your classes to use already in college.”