A Cheap, Portable Wound-Healing Device

In mid-February, about a month after a massive earthquake leveled much of Port-au-Prince, Haiti, a wound-care team from Brigham and Women's hospital in Boston traveled to the devastated capital. The team's task was to help care for scores of patients suffering from the large open wounds that accompany amputations, crushed limbs, and other injuries. Among the team was MIT graduate student Danielle Zurovcik, who arrived ready to test a device she had developed as part of her thesis research--a cheap and portable version of the negative-pressure devices currently used to speed wound healing in hospitals.

Pumping wounds: Researchers hope that a simple bellows pump attached to a tube that’s applied to a wound dressing can generate enough negative pressure to spur healing.

Zurovcik and her collaborators hope the device, which costs about $3, will provide a way to improve care for patients after the emergency phase of relief efforts, including life- and limb-saving surgeries, has ended. Even after many of the emergency medical teams leave the disaster zone, the dangers of chronic wounds remain high.

"My experience in Haiti and other major earthquakes is that after the acute medical response, such as amputating limbs and setting fractures, the major disease burden is wounds," says Robert Riviello, a trauma surgeon at Brigham and Women's, and Zurovcik's collaborator. Negative-pressure therapy decreases the need to change wound dressings from one to three times per day to once every few days, a major benefit when medical staff is in short supply.

Negative-pressure devices, which act like a vacuum over the bandaged wound, have become a central part of wound therapy in the United States over the last decade. They speed healing up to threefold, depending on the type of wound, and in some cases eliminate the need for plastic surgery or skin grafts. A number of commercial versions are available in the U.S. and are used to treat burns and chronic wounds such as bed sores or diabetic foot ulcers. While scientists don't exactly know why this treatment accelerates the healing process, it likely helps by removing some of the fluid and bacteria that accumulates at the injury site and by increasing blood flow to the wound. The pressure itself may also help healing by bringing together the edges of the wound and delivering mechanical pressure, which has been shown to spur cell growth, says Dennis Orgill, a surgeon at Brigham and Women's who was not involved in the project.

Existing devices are often heavy, about five to 10 pounds, and require an energy source to create the vacuum, making them difficult to apply in disaster settings. Texas-based KCI, the leading maker of negative-pressure machines, has a portable version that's battery powered, but it costs approximately $100 per day to rent. A number of companies are working on even more portable versions, say Orgill.

But Zurovcik, inspired by a burn surgeon's plea, went a step further, designing a human-powered device that applies pressure via a simple bellows pump weighing less than half a pound. By improving the seal around the wound dressing to reduce air leaks, Zurovcik cut the pump's power requirements from about 14 watts to 80 microwatts, which comes from a hand pump.

"To basically take a toilet plunger and produce negative pressure over a prolonged period of time, that is really great," says Kristian Olson, a physician at Massachusetts General Hospital, in Boston, who was not involved in the project. "Not only do I see it answering this need in developing countries, I think it could really enhance home therapy for chronic wounds in the U.S."

Zurovcik and Riviello had been planning a trial of the device in Rwanda--Riviello spends about half his time working in Africa--when the earthquake hit Haiti. Colleagues treating the first waves of injury victims told the duo that their device might be of help, so they joined a wound-care team headed for University Hospital, a few blocks from the leveled palace in Port-au-Prince. (Commercial negative-pressure devices, known as VACS, were employed in various relief efforts in Haiti, including $2 million worth of equipment donated by KCI.)

Working in stifling tents filled with patients, the team tended to those whose doctors had left and were in need of follow-up care. Of the hundreds of patients assessed, the researchers chose eight people suffering from a variety of injuries-- amputations, open tissue wounds, open fractures, crushing injuries (where the skin had to be opened to give the muscle room to expand), infected surgical wounds, and bedsores from being paralyzed--appropriate for negative-pressure therapy. "Because this was a disaster setting, we didn't feel it was an appropriate place for rolling out a randomized controlled trial," says Riviello. (They cared for other patients with typical dressings.)

The surgeon would first apply a sponge over the cleaned wound and then cover it with a plastic seal. A tube fed through a small hole in the plastic connected to the pump, which was manually compressed to create negative pressure. The team trained patients' families, who often took on typical nursing duties, to charge, or pump, the device. "We learned that family members are interested in being trained and motivated to keep the device charged because they saw the benefits for their loved ones," says Riviello. "They were tremendously reliable. We saw patients twice a day, but it became clear that we could come back days later and the device would still be charged."

Because the researchers were in Haiti for just 10 days, they weren't able to determine if the device helped patients heal faster. But it did seem to keep the wounds cleaner, says Riviello, and reduced the need to change bandages, which is painful for the patient. In fact, one patient requested the treatment after observing how a neighbor in the next bed was subjected to fewer painful dressing changes, says Zurovcik. Now back in Cambridge, she is tinkering with the prototype, trying to further improve the pressure seal and the amount of negative pressure the device can deliver.

The team plans a larger test in Rwanda, where it will likely put the device to broader use. People in poor countries are much less likely to survive severe burns, for example, which can be helped with negative-pressure therapy. And the rate of complications from diabetes, such as foot ulcers, is skyrocketing in these countries as well, says Olson.

By Emily Singer

From Technology Review


Maybe it will work as a 3 dollar ventilator too!

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