Chronic wounds, typically of the legs, are an increasingly common problem that can frustrate both patients and physicians. Millions of dollars are spent every year treating leg wounds and millions of hours of time are lost by patients due to the disability caused by chronic wounds and the need for numerous visits to the doctor’s office. To address these problems, wound care centers have been established by physicians with special interest and expertise in treating chronic wounds.
There are many potential causes of chronic wounds of the legs and the first step in treating a wound is to determine what caused it. By far and away the most common cause of lower extremity wounds is diabetes. Diabetes affects both the small blood vessels in the feet as well as the nerves to the legs. This results in poor circulation in the toes and feet and changes in the shape of the foot and the way in which weight is distributed. Diabetics can have very poor sensation in their feet and can develop a cut or blister without being aware of it. Other diseases such as atherosclerosis, the build up of cholesterol plaques in arteries, affect the larger blood vessels in the legs. Because of the lack of adequate blood flow, a minor scrape or injury can turn into a progressively enlarging ulcer. Disorders of the veins in the legs can also lead to chronic leg swelling with changes in the skin that make it fragile and prone to ulceration. Determining the cause of a chronic wound can often require specialized ultrasound testing to evaluate the circulation.
The first step in treating a chronic wound is to eradicate any infection in the skin or soft tissues. Often, patients have been treated with a series of antibiotics with no apparent improvement. Taking a swab of wound drainage can allow testing to determine what bacteria is causing an infection. This information allows the physician to choose an antibiotic specifically directed at that bacteria.
Or…..“You’re gonna put WHAT on my leg?”
If a wound contains a large amount of dead skin or underlying tissue it is usually beneficial to remove the dead tissue. This will reduce the infection, odor, and drainage from a wound.
Usually, the dead tissue is trimmed away with a small scalpel or scissors but on occasion the amount of tissue to be removed is too extensive or too sensitive or in a vital area. In these cases, a biologic debriding agent is sometimes used—maggots! Maggots are the larva of certain species of fly. They are usually found on dead animals but for thousands of years physicians have noted that when human wounds become infested with maggots the wounds are usually completely free of dead tissue. The maggots consume the dead tissue and leave healthy, healing tissue alone. Medical maggots are raised in the laboratory in a sterile environment and are placed in wounds that would be difficult to safely or comfortably debride with surgical instruments. The maggots are removed after a couple of days of doing their job.
Cleansing and dressing a wound is the mainstay of treatment. Often the wrong type of cleaning agent or dressing can prolong the healing of a wound. The most common example is hydrogen peroxide. When applied to a wound it produces a very satisfying foaming action–clearly it is doing something! While it certainly kills bacteria it also kills the new skin cells that are trying to grow into a wound. Gentle cleaning with warm water and a mild soap is usually all that is necessary. Allowing a wound to dry out, or desiccate also results in the death of the cells on a wound surface. Most wound dressing materials in use today act to provide a slightly moist wound environment. Too much drainage from a wound can result in too much moisture, however, and the surrounding skin can be adversely affected. Bacterial or fungal infection may be the result if the skin around a wound is wet all the time. In this situation, there are dressing materials available that are extremely absorbent and are impregnated with antibiotics. Some wounds need a to be cleansed and dressed daily or several times per day–these are usually wounds that are complicated by infection. Other wounds may benefit from the use of dressing materials that can stay in place for several days. These are often combined with an elastic wrap on the leg to help control edema. It is beyond the scope of this article to describe the many different products available for wound treatment. Picking the right dressing material for a given wound is a little bit art and a little bit science.
Negative Pressure Wound Dressings
One type of wound care device that deserves special mention is the negative pressure dressing. Wounds that involve the loss of a large amount of tissue or wounds that result in the exposure of bone or tendon are especially difficult to treat. These types of wounds respond to the use of a sponge-like dressing material that is used to fill in the depths of the wound. It is then covered with an air-tight plastic and connected to a suction pump. The resulting negative pressure under the plastic pulls the wound edges together and stimulates the growth of new tissue into the wound. The results in large and deep wounds can be dramatic and the healing time can be considerably shortened.
Relief of Pressure
Excessive pressure results in many diabetic foot ulcers and heel ulcers. It is imperative to relieve the pressure on the tissues to get these wounds to heal. Special shoes or boots can be used to prevent pressure on an ulcer. The use of a special type of cast on the foot has been very successful in treating diabetic foot ulcers. The cast is carefully constructed to immobilize the foot and padding within the cast isolates the wound and distributes the pressure evenly over the rest of the foot.
Hyperbaric Oxygen Treatment
Adequate levels of oxygen in the tissues is essential for wound healing. In certain situations there may not be adequate tissue oxygen levels despite apparently normal circulation. Diseases that affect the micro-vascular circulation, such as diabetes, can cause low tissue oxygen levels within and around a wound. A treatment called hyperbaric oxygen is useful in many patients with these types of wounds. Patients are placed into a pressure chamber and breathe very high concentrations of oxygen at high pressures for brief periods. This dramatically raises the concentration of oxygen in the bloodstream and in the tissues. While the increase in oxygen in the tissues is only temporary, it provides a tremendous stimulus for the growth of new blood vessels into a wound which ultimately increases the tissue oxygen levels and leads to healing.
Despite all the measures mentioned above, some wounds will make little or no progress towards healing. Biologic dressings are another tool available to treat these difficult wounds. These materials which can be derivatives of animal tissues or even human skin that has been grown in the laboratory in tissue culture deliver important proteins called growth factors to the surface of a wound. These materials also provide a scaffolding for the ingrowth of new skin cells into a wound.
As you can see, wound care physicians have an amazing armamentarium available to treat and heal wounds that not long ago might have necessitated the amputation of a limb. The ability of the human body to heal a wound is truly a miraculous process–sometimes it just needs a little help and that is what we, as wound care specialists can provide.