Most patients facing heart surgery aren’t so much afraid of the surgery as they are about their ribs spreading to make way for the surgery. As anyone who’s broken a rib knows, it’s just about the most painful injury you can have. But two experts in the field of biomechanics have found a way to make it slightly less traumatic.
Instead of breaking ribs with a crank, the traditional way, Hugh Crenshaw, Ph.D., and Charles Pell discovered a way to do it with a motor, putting much less stress on bones. Both got their start in biomechanics and over the past 20 years they’ve translated their understanding of biomechanics into inventions from robotic submarines to pill sorters, according to a recent story in the New York Times.
But now these owners of a medical technology company called Physcient, based in Durham, N.C., have turned their attention to how bones can bend, rather than break.
Every year surgeons use rib spreaders to open the chests of an estimated two million people to repair their hearts and then close them back up. All the rib spreaders today are based on a model invented by an Argentine surgeon in 1936, who used a hand-turned crank to pull apart two metal arms, according to the New York Times, but which can cause serious side effects.
Between 10 and 34 percent of patients wind up with broken ribs, nerves are sometimes crushed and ligaments can be ripped. After surgery, some patients require heavy sedation for the pain, and their shallow breathing can make them vulnerable to pneumonia. Even after leaving the hospital, some patients continue to feel pain for months.
Crenshaw and Pell and other scientists from Physient began experimenting on pigs, which are similar in bone structure to humans. They found that the rib spreader commonly used delivered jolts of force that increased until they equaled the weight of the pig’s entire body. Physcient combines modern automation and knowledge of surgical biomechanics to develop minimally traumatic surgical devices.
When the body is entered from the side, the ribs are spread apart to give enough room for the surgeon to work. Ribs are flexible, so they can be spread some before they break. Once the opening is large enough, a small incision is made in the lung and a tube is inserted. Cutting the lung causes it to deflate, which gets it out of the way so the surgeon can see what he is doing. Once the surgeon is finished and ready to close, air flows through the tube to re-inflate the lung slightly. The tube is removed and the lung incision closed, and your breathing will re-inflate the lung.
What the team found was that bones may be hard, but they’re not brittle. Stretchy collagen fibers and other elastic proteins allow them to flex, like a tree branch. Crenshaw, Pell and their colleagues set out to build a rib spreader that took advantage of the physics of bone and other tissues. They came up with a prototype that, instead of two straight bars, had two rows of curved metal hooks, each of which could independently cradle a single rib or part of the sternum, according to the New York Times.
The team programmed the rib spreader’s onboard computer to stop advancing it within a quarter of a second of sensing a pop, what usually happens right before a bone breaks, allowing the fibers in the bones and ligaments to shift and stretch before it starts moving again.
The researchers also found that in the Physient trials, the pigs had higher blood oxygen levels than when surgeons used traditional rib spreaders, because could breathe more deeply. The pigs also needed fewer painkillers, and recovered more easily.
Want to learn more about the latest in communications and technology? Then be sure to attend ITEXPO West 2011, taking place Sept. 13-15, 2011, in Austin, Texas. ITEXPO offers an educational program to help corporate decision makers select the right IP-based voice, video, fax and unified communications solutions to improve their operations. It's also where service providers learn how to profitably roll out the services their subscribers are clamoring for – and where resellers can learn about new growth opportunities. To register, click here.
Deborah DiSesa Hirsch is an award-winning health and technology writer who has worked for newspapers, magazines and IBM in her 20-year career. To read more of her articles, please visit her columnist page.
Edited by
Jennifer Russell
