February 8, 2005

NC State Engineers Design Device to Reduce Pain in Heart Surgery Patients

— Researchers have designed an instrumented retractor that can help doctors reduce post-surgical pain

The prototype device uses six instrumented blades to retract the ribcage to give surgeons access to the heart during surgery. (Image: courtesy Dr. Gregory Buckner)

Each year, more than 700,000 Americans undergo open-heart surgery. In addition to the many risks associated with this procedure, it can result in post-operative pain lasting for months or even years. A primary cause of this pain is opening the ribcage for access to the heart.

Researchers at North Carolina State University are working to reduce post-operative pain associated with open-heart surgery. Dr. Gregory Buckner, associate professor of mechanical and aerospace engineering at NC State, and Nicholas Jardine, undergraduate research assistant in biomedical engineering, are collaborating with surgeons from the University of Chicago to develop a force-controlled retraction device that can help doctors reduce post-surgical pain.

When doctors open the chest of a heart surgery patient, they use a standard retractor with two steel blades to pry the ribcage open either at the sternum or between the ribs. The forces exerted by these blades can result in rib fractures, nerve tissue damage or other trauma. The instrumented retraction device designed by Buckner’s group features six adjustable blades to help distribute the forces.

This image shows the components of the second prototype retractor. (Image: courtesy Dr. Gregory Buckner)

“Our design uses pivoting blades with embedded sensors to measure retraction forces and give immediate feedback to the surgeon,” said Buckner. “Our first prototype was tested on cadavers at the University of Chicago. Results from these trials led to design modifications in our second prototype.”

Dr. Gil Bolotin, a surgical specialist at the University of Chicago, performed surgeries at NC State's College of Veterinary Medicine to compare the second-generation prototype to a conventional retractor.  The researchers found that monitoring retraction forces during surgery resulted in significantly lower forces on the ribcage. They also documented a reduction in rib fractures from five incidences with conventional retraction to one incident with instrumented retraction. Buckner reported these findings at the New Era Cardiac Surgery Technology Conference held in Laguna Niguel, Calif., last month.

The research team has applied for a patent on the device and recently received approval to conduct a 70-patient clinical trial on human patients at the University of Chicago Hospitals. They are awaiting funding from the National Institutes of Health before starting the clinical trials.

“The results from our animal trials are encouraging, but we still need to correlate reduced retraction forces to reduced post-operative pain,” says Buckner. “We hope to document this correlation through clinical trials.”

— weston —

Media contact:
Jennifer Weston, (919) 515-3848, weston@ncsu.edu

Technical contact:
Dr. Greg Buckner, (919) 515-5270, greg_buckner@ncsu.edu

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