When it comes to medical procedures, horses are like young children, says Melissa Mazan, V93, professor of large animal medicine at the Cummings School of Veterinary Medicine. Horses do not necessarily comply with requests to stand still or hold their breath, making it extremely difficult to test their lung function, which is critical to the success of equine athletes.
“Equine asthma is a significant cause of poor performance for high performance horses, second only to lameness, and a quality of life issue for older horses with chronic conditions that can essentially become respiratory cripples. Horses with advanced disease are not difficult to diagnose on the farm, but in young athletic horses it can be nearly impossible to detect,” explains Mazan.
This is often a quiet condition, other than a slower running time, as these horses are in very good shape. But, she adds, they win or lose races by the hundredth of a second, so “it only takes a little insult to the respiratory system to take a horse from first place to the back of the field.”
The Hospital for Large Animals is one of the only centers in the United States that performs pulmonary function testing on equine clinical cases, but customers must travel to Grafton because the testing systems are elaborate. This poses a problem that has plagued Mazan for decades: How can the hospital diagnose lung function in horses it cannot bring to the clinic?
“What we’re looking for is if the horse’s airway has more resistance than normal to airflow,” Mazan says. “If the resistance is high, then the work of breathing has to increase, which is work a horse cannot put into cantering or jumping.”
In human medicine, lung function can be measured using portable tests called peak flow meters, which measure the amount of air flowing in and out of the lungs. They require the person being tested to take a deep breath in and forcefully exhale until their lungs are empty. But with children, lung function tests are often done using a method that doesn’t require them to follow such instructions.
This is called the interrupt system, and the idea is that the child wears a mask or mouthpiece with a sensor to measure air coming in and out, and as they breathe steadily, a shutter very fast cuts off breathing for a fraction of a second. It’s so fast that kids don’t even notice it.
“The idea is that if you turn off the breath for a very short period of time, the pressure in your lungs balances out with the pressure inside that mask,” Mazan explains. “To get resistance, you need to be able to measure airflow and pressure. The interrupt method allows you to do both.
She felt that something similar might work with horses, and the idea for a portable device to test equine lung function began to form.
Invent a veterinary tool
In 2018, Mazan pitched his idea to Kristen Wendell, an associate professor of mechanical engineering in the School of Engineering, who was looking for projects her fourth-year students could do for their design assignment. She tries to find clients who have mechanical design needs but not necessarily the resources, knowledge or time to do them themselves, and her students work on the project as a kind of customer service.
“When Dr. Mazan told me about her idea, I was so excited about the alignment with the kinds of issues I wanted my students to address,” Wendell recalls. “It was a very multifaceted design problem in terms of the mechanical engineering concepts required, such as fluid flow, machine design, weight and geometry, electronic sensors, and computer programming.”
Wendell’s students were given the opportunity to choose from a handful of possible projects, but the appeal of the complexity of the problem and working with live horses was very strong. Several students accepted Mazan’s challenge, including Thomas Coons, Christopher Simotas and Brian Barrows, all E19. The initial goal was not to create the entire device; rather to first develop parts that satisfied the needs defined by Mazan.
The team split into two small groups, one focused on determining the airflow measurement and the other on pressure. Coons and Simotas were part of the airflow team and they ran into two main obstacles. The first was that volumetric flow sensors can be very expensive. The second issue was that it is very difficult to measure volumetric airflow, or the amount of air passing, with cheaper air velocity sensors. Barrows was part of the pressure team, where the main objective was to ensure that the shutter system, which caused the breathing to stop, operated smoothly and gave an accurate reading of the pressure differential.
“Our task was to create a system that could interrupt breathing for just 300 milliseconds,” says Barrows, who now works for iRobot. “Getting a large valve to move so quickly was hard enough, but we also needed it to be quiet to avoid spooking the horse.”
While the team apparently spun the wheels a lot on these issues, they ended up finding creative solutions in some surprising places. For example, the team was looking for a large pneumatic valve and several engineering companies told Mazan that what they wanted did not exist. However, she ended up finding key parts at an RV retailer, which uses large pneumatic valves in RV toilet systems, and at a Halloween supply store, because Halloween decorations often use pneumatics to achieve their creepy effects.
“What makes design work difficult is that you don’t solve a problem with a clear answer. You need to understand what the customer is trying to achieve and what are, from an engineering perspective, the most important issues to solve to get there,” says Coons.
The group presented their prototype to Wendell and Mazan regularly throughout the semester for demonstrations and feedback rounds, and Wendell says they all got A’s on their capstone project.
“At the end of the semester, Professor Wendell created a matrix on the board with each class project listed in various engineering disciplines such as materials, programming, and heat transfer. She then asked our class to reflect on the disciplines with which our projects interact. To our surprise, ours hit every single one of them,” says Simotas, who now works for Raytheon Technologies. “We were very proud of all we were able to accomplish and were impressed with all the tools we had acquired in our tool belt over our four years. It was a great and inspiring learning experience.
Although they passed Mazan’s challenge, the device was far from complete. Coons, Simotas, and Barrows graduated in the spring of 2019, and Mazan was impressed with how far they pushed the design. She asked them if they wanted to continue collaborating on the device, and they all said yes, as they loved Mazan’s infectious energy and passion while working on this “fun side project.”
Over the rest of the year, they built more of the device and traveled to the Grafton campus to meet with Mazan and test the prototype on equine patients. Horses only breathe through their noses, but a clear plastic mask covers their nose and mouth to help the mask stay in place. “Horses are used to wearing things, like bits or halters, and they tolerate it very, very well,” says Mazan. “At the front of the mask is an opening where the flow meter and valve are located. Horses breathe through it normally, the valve closes and a pressure transducer on each side of the mask measures the difference between the pressure inside and outside the mask.
Before the team tested the device on a horse, Mazan used herself as a guinea pig. She put on the mask and gave her husband power over the button that closes the valve to stop breathing, so she couldn’t anticipate when it would happen. The interruption was so quick that she never noticed a hindrance, she says. And after testing the device on live horses, which have much larger lungs and slower breathing than humans, the team found they didn’t seem to notice the interruption at all.
In early 2020, Mazan and the former engineers met with intellectual property lawyers to see if they could patent their system. When the COVID-19 pandemic hit, the collaboration stopped for a while. Mazan tinkered with the system herself from home, responding to suggestions from lawyers to beef up the device and make it more patent-ready.
For engineers who have worked with Mazan, the possibility that their name could appear on a medical device patent so early in their engineering career is staggering. “I’ve been on the faculty at Tufts for six years, and during that time it’s the only patent application I’ve seen coming out of the cornerstone of mechanical engineering,” Wendell says. “There were before I arrived, but it’s very rare that it happens.”
Where are things now
More recently, with the help of face masks, vaccines and rapid tests, group work has resumed, although the team is slightly smaller since Coons is currently pursuing a doctorate. in Mechanical Engineering from the University of Michigan. Mazan is immersed in clinical trials. So far, the results are incredibly promising.
“When we compare it to our gold standard, which is called the pneumatic esophageal balloon method, the precision is very high. We get the same resistance measurements with both methods,” says Mazan. “You might ask, ‘if this is the gold standard, why don’t you do it all the time?’ Because it’s a giant pain in the neck. You literally have to pass a balloon through their nose and they have to swallow it down their esophagus. Horses that aren’t used to this process will object.
Mazan intends to return with the legal team to complete the patent on the device and hopefully find a company that would like to sell it. “I always tell engineers that nobody’s going to get rich on this one,” she laughs. “It’s just fun, and I hope it helps.”
Testing a new therapy for horses struggling to breathe
A new portable device to test equine lung function (2022, April 5)
retrieved 5 April 2022
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