Understanding Efficacy of E-Stim for Wound Healing
By Lisa Dress
The acceptance of electrical stimulation for chronic wound healing by the medical community has been a long and complex process, said Carrie Sussman, PT, owner of Wound Care Management Services, in Torrance, CA.
Sussman, who has been using electrical stimulation to treat geriatric patients with chronic wounds since the early 1980s, said there was little information in the literature to support the use of the modality for wound healing at that time.
Today, almost 20 years later, Sussman said electrical stimulation has been well-documented in the literature for its effectiveness in healing chronic wounds and is widely used among physical therapists.
Electrical stimulation works by enhancing the body's bioelectric system on a cellular level. When the skin is wounded, it conducts a current generated between the surface skin (a negative current) and the inner tissues (a positive current) in an attempt to attract healing cells, which are responsible for releasing growth factors that are involved in the process of collagen synthesis. This process is referred to as the "current of injury," and will continue until the injury is healed, Sussman noted.
A moist wound environment is required for the body's bioelectrical system to function properly. "There must be a medium to conduct a current. If the wound is dry then that medium is lost," Sussman said.
LACK OF CURRENT, or current disruption, is suspected to be one of the reasons why chronic wounds do not heal without an outside stimulus to jump-start the healing process. The rationale for applying electrical stimulation is that it mimics the natural current of injury and initiates or accelerates the wound healing process, she said.
The process of a wound healing takes place in four phases, according to Sussman. During the first phase, or inflammation phase, the wound is tender, swollen and inflamed. It is during the first phase that the body begins the healing process. During the second phase, or cell proliferation phase, newly generated cells form and begin to replace the damaged ones. During the third phase, the epithelialization phase, the cells are restructured to replicate and reproduce skin or scar on the damaged area. Remodeling of the skin is the final phase.
Electrical stimulation facilitates these steps via an electrical current which transfers energy to a wound through two electrodes. One is placed on the external skin a distance away from the wound and the other in the wound bed. The electrical source controls the current that is being transferred.
Although there are many waveforms available for use in electrotherapy equipment, according to Sussman, the most commonly used current for wound healing is a monophasic twin peaked high voltage pulsed current.
HVPC gives the cells an interrupted type of stimulus and causes the body to respond to the stimulation by laying down collagen. HVPC also allows for the control of the polarity and variation in pulse rates, which are both important to the healing process, she added.
Treatments are generally either 30 minutes twice a day or an hour a day three to seven times a week, depending on the severity of the wound and the setting. Sussman said improvements in the patient's condition should be seen in about a two-week period. "There should be changes in the tissue in the wound, in the surrounding skin and a change in the secretion from the wound." If there is no change in two weeks, the parameters of the treatment (electrode placement or polarity of current, for example) should be changed or treatment should be discontinued. Mean healing time reported in the literature ranges from about seven and a half to 10 weeks. (Feeder, et al, Physical Therapy, 1991; 71: 639-649.)
"If patients can take the treatment home with them, they can do it everyday. But if patients have to go to the clinic, they may not be able to make it every day," she explained. She added that home treatment is an option for patients who have a less severe wound, or one that has begun the healing process on its own.
"The opportunities for individualizing care with electrical stimulation are very good. The PT can customize the treatment depending on the setting, severity of the wound and the patients' or caregivers' capability of administering the electrical modality."
The opportunities to use electrical stimulation for healing chronic wounds are plentiful since they often don't heal in a normal manner. A chronic wound is one that has not responded to conventional therapies, such as dressings and medication, in a 30-day period, Sussman noted. The depth of the wound, as well as wound deterioration (has it gotten deeper, infected, or larger) are other critical factors in determining if electrotherapy may be necessary.
Chronic wounds vary in "thickness" from partial to full thickness to deep skin loss extending into tissue. "Deeper tissue takes longer to heal, so what really matters is the depth of the wound. The actual size of the wound on the surface is not as critical as the depth," Sussman noted.
THESE WOUNDS are not rare. "There are may different etiologies that can result in chronic wounds. A chronic wound doesn't require an underlying disease or condition. A tummy-tuck could result in a chronic wound," although the most common are pressure ulcers (stages I through IV) diabetic ulcers, resulting from pressure, insensitivity and dysvascularity and wounds resulting from venous disease.
Venous disease is a condition where the veins in the legs have incompetent valves and thus lose the ability to keep blood from back flowing and pooling at the ankles. The blood "back-ups" in the veins which then begin to stretch and leak blood into the surrounding tissue. This causes swelling and the eventual breakdown of the skin, which ultimately leads to wounds.
Chronic wounds are also the result of ischemia or vasculitis and can develop from a post-surgical wound that did not heal properly, or from a traumatic injury, such as a puncture wound.
The most prevalent chronic wounds are pressure ulcers. People who are immobile or have lack of sensation (in the feet, for example, due to peripheral neuropathy or spinal cord injury) are at greatest risk for developing chronic wounds.
Many experts believe that pressure ulcers are chronic wounds from the onset, since there is deep tissue death that is incapable of repair by the body. The wound is therefore unable to heal in a normal fashion.
Fourteen million people in the United States, with diagnosed or undiagnosed diabetes are likely to develop ulcers, Sussman said. "When there is an impairment of sensation, then the risk factors increase and the probability of ulcers developing over bony prominences such as heels and toes is greater."
CHRONIC WOUNDS can develop from pressure sustained over a few hour period--to prolonged pressure--or even heavy loads of pressure on a very small area of the body for a short period. This pressure blocks the normal blood flow in the area where the pressure is sustained, and tissue begins to die. "That's how a pressure wound begins." Patients who have compromised immune systems are also at risk for developing chronic wounds.
Chronic wounds, besides being painful, often provoke feelings of depression and low self-esteem, and limit patients' leisure, play and work activities, Sussman noted. These wounds also put stress on the family. "Caring for a person with a chronic [wound] is a big family responsibility. It takes constant care and intervention."
Chronic wounds also result in the loss of function and amputations. "Patients often have amputations due to a wound that doesn't heal. The diabetic foot ulcer population, for example, has an extremely high rate of amputations," Sussman noted. For some of these people electrical stimulation can be a life-altering option.
According to Sussman, electrical stimulation initiates the healing process throughout the biological phases of wound healing. In the inflammation phase, it increases blood flow for enhanced tissue oxygenation and phagocytosis, improves membrane transport and cellular permeability, and stimulates DNA synthesis. In addition, it may affect the current of injury. During the proliferation phase electrical stimulation enhances collagen production and wound contraction. During the third phase of healing, the epithelialization phase, electrical stimulation stimulates epidermal cell reproduction and migration. Finally, during remodeling, wounds that have been treated with electrical stimulation have smoother, thinner and stronger scar formation, Sussman said.
Although many therapists are convinced of the efficacy of electrical stimulation in the treatment of wound healing, the Health Care Financing Administration announced that Medicare will not continue to reimburse for the use of electrical stimulation for wounds, beginning last Monday, July 14.
Sussman said she is angry and disappointed with the agency's decision. "The action by HCFA was very disturbing and [if their decision stands] the consequences will be very severe for patients." About 90 percent of patients who receive electrical stimulation for chronic wounds are Medicare beneficiaries, she added.
THE APTA is currently reviewing legal alternatives to halt the noncoverage policy, said Nancy Garland, APTA director of government affairs. "If we don't go to bat for [electrical stimulation for wound healing], who will?" Sussman noted. "PTs have the best background in evaluating the benefits of the treatment."
(Look for the full story on reimbursement of electrical modalities in
ADVANCE's Sept. 15 issue).
* For more information, contact Carrie Sussman at (310) 375-8815.