Connor McBride (foreground), Edward Ruppel, and Chandler Woo (at rear) with one of the endoscopes they’ve designed to extract objects that become lodged in a pet’s esophagus or stomach. (Photo by Bob Marcotte/University of Rochester)

A better way to extract the objects
that don’t belong in a dog’s stomach

There is a widespread misconception that most pets can easily “pass” the objects they swallow.

Erika De Papp knows better. A veterinarian with the MSPCA-Angell humane organization in Massachusetts, she often struggles to extract objects lodged in a pet’s stomach or esophagus.

So when she heard about the Department of Biomedical Engineering senior design program from her nephew, who is a student in the department, she proposed a project:

Build me a better device than what’s on the market now to extract these objects.

Seniors Connor McBride, Edward Ruppel, and Chandler Woo believe they’ve done exactly that.

“Her pitch to us was that one of the common issues with current devices is that it is very difficult to grasp an object in an animal’s stomach,” Woo says. “ Some procedures last up to an hour and half, and when it gets too frustrating, they resort to surgery. Obviously it would be better to be less invasive.”

The team’s device inserts a small plastic tube down the esophagus and into the stomach. Inside the tube is a wire that can be extended out the end of the tube, deploying into a cage-like head that fits around the object.

When inserted in the biopsy port of an endoscope with a camera in its tip, it allows one member of the veterinary team to keep the object in view, while the other secures the object.

“We’ve focused this design on 40 to 60 pound dogs, but could easily adjust the length to work with humans, chimpanzees, giraffes – whatever you want,” says Ruppel.

Though similar devices are already on the market, they are limited to sliding the wire forward and back (a single “degree of freedom”). They require the veterinarian to choose from myriad head shapes, and they often deform and have to be discarded.

The team’s device, now in its third “iteration”, is more robust. It incorporates two additional degrees of freedom – rotation and translation -- “for additional precision” in maneuvering the head to grasp the object, McBride explains.

For example, the wire head can be rotated – crucial to realigning a shard of bone so it does not tear the stomach or esophagus as it is pulled out, Woo says. The tube itself can be bent, or translated.

And the device can be locked in place at any point during the procedure, which makes it easier for the other member of the team to lend a hand during the extraction, Ruppel says.

Those additional degrees of freedom exceeded the team’s initial assessment of what they needed to do to meet their client’s needs. “We wanted to take the design further,” Woo says,

The components, designed in Solidworks, can be fabricated with injection molding. “This puts us in position to easily commercialize if given the opportunity,” Ruppel says. The team is working with UR Ventures, the University’s tech transfer office, to assess the possibility of a patent.

The biggest challenge for the team: the narrow tolerances of the design.  “We were working with 2 millimeter tubing, which is really small. We had to be sure when we ordered wire (custom-made) that it would fit inside,” McBride says.

The other challenge was staying within budget. The teams are allotted $150 per member. “It’s actually good to know we’re within a limited budget,” Woo says. “That’s something we have to learn for the work we’ll be doing in the future.”

It helped that Ruppel was familiar with the 3-D printing and other resources at the fabrication lab at Rettner Hall, which helped keep down costs. Ruppel is president of the Solar Splash team, which builds a solar powered boat to compete against other universities.

All three members of the team will pursue graduate degrees in medical device development. Ruppel will be in the master’s program at the Center for Bioengineering Innovation and Design at Johns Hopkins.  McBride will remain at Rochester with the Center for Medical Technology and Innovation master’s program in medical device design. And Woo will attend Rice University, pursuing a master’s in its global medical innovation track, which trains students to develop low-cost solutions for emerging countries.

“That was one of the cool things about this project,” Woo says. “This is the sort of path we all want to pursue.”