Undergraduate engineers design neonatal ECMO simulation
|A team of mechanical engineering students designed a neonatal ECMO simulation for their senior design project.
San Diego, Calif., May 11, 2020 -- In collaboration with physicians and surgeons at Rady Children’s Hospital- San Diego, a team of undergraduate mechanical engineering students developed a neonatal simulation system for a critical and rare surgical procedure called ECMO. They developed this realistic simulation system- believed to be the first for neonatal patients—for their senior design project.
ECMO—extracorporeal membrane oxygenation-- is a rare procedure used when a patient’s heart or lungs aren’t able to function. Doctors use a machine to circulate and oxygenate the patient’s blood by pumping it through an external system of tubes and filters outside of their body, through an artificial lung, and back into the body.
ECMO is used for patients recovering from heart or lung surgery; for people whose heart or lungs aren’t functioning; or for infants experiencing respiratory or cardiac distress. The procedure is rare, particularly for children—at Rady Children’s, it’s only performed a handful of times per year. However, it has been used more often during the COVID-19 pandemic as a means to give patient’s lungs time and capacity to heal.
“ECMO is done very rarely on children and infants, which makes it higher risk; both because it’s so rare that it can be difficult to train for, and because they’re physically smaller so it’s harder to put the cannulas into the artery and vein,” said Guinevere Berg, an engineering student on the team.
Since the procedure is so rare yet so complex, physicians rely on simulations to properly train to perform the operation. Existing simulations aren’t always very realistic, with mock arteries strapped outside of mannequins, and high-end ones can cost several thousand dollars, precluding some clinics from having sufficient training opportunities.
The parts required for the students’ design cost $70, and most of them are reusable for multiple simulations.
“They have one pediatric ECMO simulation at Rady now, but they don’t have one at every hospital because they tend to be really expensive and difficult to make. There are currently no neonatal sized simulators,” said Samantha Landis, another team member. “Our goal was to create an ECMO simulation system for a neonatal infant and to reduce the cost, so we can spread this method to other hospitals, especially lower resourced hospitals.”
|The neonatal ECMO simulation, with the interior components shown outside of the mannequin.
The students developed low cost, easy to replicate artificial arteries and musculature that are placed in a 3D-printed holder inside the neck of an off-the-shelf neonatal-sized mannequin. They placed artificially created skin over the neck, where doctors make an incision during the simulated procedure to insert a tube into the arteries. The students also developed a pump system to circulate the blood in the mannequin’s vasculature, which existing simulators don’t have. They even went so far as to devise a new formulation for mock blood to make it feel, look and smell more realistic. Many current simulators use a bag with saline solution and red food dye hung on an IV pole to mimic blood circulating in the body.
“We added a pump with different size tubings and fittings, so that arteries had a different pressure than blood flowing through than veins,” said student Rahaf Alharbi.
They used glycerin, water, coloring and iron capsules to develop a substance that would flow, feel and smell more like blood.
Student Yichen Cai said they also devised a way to tension the muscles, so that they’d react and retract as they do in vivo when a physician is making the incision to insert a tube into the artery.
A team of surgeons, doctors, nurses and technicians at Rady Children’s tested their simulator, and were pleased. They plan to present it at an ECMO conference later this year, including a manual the students created detailing where to source and how to make the required components. The total cost of their simulator was $70, and it can be easily scaled up to a larger size for a pediatric or adult ECMO simulator.
“The Rady ECMO team is very thankful for this opportunity,” said project sponsor Dr. Denise Suttner, clinical director of the neonatal intensive care unit at Rady Children's Hospital and director of the San Diego Regional ECMO Program. “The simulation is very impressive and has added great value to our educational offerings.”
The students said this hands-on project was also valuable to them for several reasons.
“I think a lot of our prior practice stemmed from theoretical knowledge, and in the beginning of the project we were kind of stressed out because we couldn’t find any literature, any studies or any equations to help us with this. But when we realized we can move to other methods that designers really use, it helped us a lot,” said Alharbi.
|The students met with Rady physicians and surgeons frequently to ensure the design met their needs, and are pictured here after a Rady team tested their completed ECMO simulation.
“It ended up being almost entirely qualitative, not quantitative, which is very different from a lot of engineering courses,” Berg added. “The main measure of success was ‘Does this feel real to surgeons?’”
Knowing that their project could one day help physicians and patients was a motivating factor, too.
“We combined an engineering approach along with a human-centered design approach to solve a real world problem,” said team member Reem Mohanty. “I think our team’s interdisciplinary application of design thinking and engineering tools was a unique and creative idea. The course gave us an avenue to potentially make a difference in people’s lives and that really motivated us to give our best.”
Jacobs School of Engineering