Pressure and time: combine the two and you can get a multitude of results. Apply the two to coal and you’ll eventually get diamonds. Apply them to human flesh, and in a much shorter time, you will get pressure ulcers…painful areas of necrosis and ulceration that are a bane for any patient confined to a bed for long periods of time. They are also a frustrating fact of life for anyone confined to a wheelchair, especially those patients who have little or no feeling in the lower half of their body.

“Pressure ulcers are one of those things that are a big clinical problem for many people with limited mobility,” explained Kath Bogie, PhD, a research scientist at the Cleveland Department of Veterans Affairs Medical Center. “If you can’t move, sooner rather than later, your skin will start to break down. It starts off as a small wound, and very rapidly develops into a big wound that takes an awful lot longer to heal than it does to develop.”

With a background and training in bioengineering, Dr. Bogie has dedicated her time at VA to finding new and innovative ways to prevent and better treat pressure ulcers in wheelchair-bound patients.

An Insidious Wound

Pressure ulcers result from the breakdown of skin when a patient stays in one position for too long, especially in areas that have bones close to the skin, such as the hips. The skin is pressed between the bone and the surface a patient is sitting or lying on. What begins as a reddened area of skin turns into an open sore that eventually will turn into a crater that might become so deep that it reaches to underlying muscle and bone. A pressure ulcer can form in less than a day if a person is left in the same position.

Pressure ulcers can quickly become a chronic wound problem for patients with limited mobility, particularly for those who are entirely without feeling in the lower half of their body.

“One of the reasons for looking specifically at people with spinal cord injuries is that they have both the problems of limited mobility along with the inability to feel that they’re starting to get pressure ulcers,” Dr. Bogie explained. “Other people with reduced mobility [will] feel uncomfortable and try to do something to move. If you don’t feel, you don’t even have the cue that you want to start moving. This has implications for other groups that have tissue breakdown, such as the elderly. Even people in acute care conditions—if you end up in the emergency rooma nd you don’t move for 5 or 6 hours, you are at risk of getting a pressure ulcer. You can be healthy in th emorning, and by midafternoon, have the risk of getting a pressure ulcer.”

“Within the spinal cord injury population in particular, pressure ulcers occur at a remarkably high rate, which doesn’t seem to have decreased greatly, even as other medical advances have come about,” she noted.

Though they are a relatively widespread problem, that does not undermine their effect on patients or on hospitals. Pressure ulcers create a painful new problem for patients already suffering from another ailment, and treatment costs hospitals time, money, and personnel. A hospital patient being treated for a pressure ulcer is generally turned over in their bed as many as 12 times a day to relieve pressure. Nurses spend time changing dressings, applying ointments and topical medication, and vacuuming away detritus from the wound. And if that pressure ulcer becomes infected, it will likely become the primary cause for concern for health care staff, and can cost the hospital as many as $50,000 to treat.

An Electrical Solution

The key to preventing pressure ulcers is for a person to avoid staying in the same position for too long. While bedbound patients are turned on a regular basis by nurses if they cannot do it for themselves, wheelchair bound patients are instructed to lift themselves out of their wheelchair for at least 3 minutes out of every 20. “It’s hard work,” Dr. Bogie said. “So very, very few people actually can do it.”

So, how do you relieve that pressure for patients who do not have the strength or mobility to do it for themselves? Dr Bogie has found what she believes to be the solution in neuromuscular electrical stimulation. In a study performed through the Cleveland VAMC, Dr Bogie has implanted percutaneous electrodes in the gluteal muscles of wheelchair bound, paralyzed patients. The electrodes are used in conjunction with a programmable electrical stimulation system designed to send an electrical current into the paralyzed muscles, allowing them to contract.

The stimulation program will produce contractions, alternating between the left and right side of the buttocks. The result is a slight rocking from side to side continually for 3 minutes. Then it will stop for 17 minutes. The pattern will continue for as long as the patient is sitting up in their wheelchair.

“We can’t make the muscle respond quite in the normal way it would if it were not paralyzed, but you can make it have an active contraction,” Dr. Bogie explained. “By making them contract, what we’re doing is changing the conditions at the interface between the person who’s sitting in the wheelchair and the cushion in that wheelchair.”

Paralyzed muscles atrophy and the result is the withering of the natural cushion gluteal muscles provide when sitting. That cushion would normally provide a barrier between skin and bones, helping to prevent pressure ulcers. By electrically contracting those gluteal muscles over time, the result is much like when a person begins working out. Muscles start to bulk up. Blood flow improves. The muscles regain fatigue resistance.

“All of those changes are things that help lower the risk of pressure ulcers,” Dr. Bogie explained. “You’re improving the contour of what you’re sitting on. And also because we’re contracting the muscle, we can produce weight shifting. If you imagine one side contracting and then the other side contracting, what you get is a slight shift from side to side. By doing this, you’re producing movement. And what we’ve found is that this is enough movement to prevent pressure ulcers.”

Moving Forward

The study has been a relatively small one, with only five patients receiving the implanted electrodes. And while she cannot say clinically that the system prevents pressure ulcers, Dr Bogie can say that the system improves blood flow and pressure distribution, both of which are good signs that the high risk of pressure ulcers is being significantly lowered.

“We have had people with high levels of quadriplegia who have used the system for more than 5 years and have had good clinical results,” she explained. “Previously, they would get tissue breakdown on a fairly regular basis, and since they’ve started using the system, they no longer get breakdown.”

“These patients helped us show that the intervention works. It produced all of these positive changes,” she declared. The study has been enough of a success that Dr Bogie is looking to the next generation of the stimulation system, improving on the first one.

“The first system could work up to 10 hours a day, which is good for most people, because that’s as long as they’re up in a wheelchair generally. The next generation system will be able to work for as long as the user wants it to work,” Dr. Bogie said.

As it stands, the system is already highly user friendly. Because the electrodes are implanted, the system just needs to be turned on and off every day. The implantation is done as an outpatient procedure and takes between 4 and 6 hours. The patients go home, recover from the procedure, and start using the stimulation system. “[Making it user-friendly] is the goal,” she said. “If we’re going to make something for people that have a lot of challenges in their life already, we don’t want to add anything that will make their lives more difficult.”