Evaluating a new technique for the treatment of chronic wounds

An acute wound, such as a surgical incision, is likely to heal without complications in patients in the UK (Bale and Jones, 1997). In a relatively fit and well individual, it should repair itself fairly quickly, owing to the cascade of protein-based growth factors and cellular stimulants present in acute wound fluid that initiate the healing process (Bryant, 2000; Chen, 1998). In contrast, the status of non-healing chronic wounds, such as leg ulcers and pressure sores, is not yet fully understood, and such wounds may persist for a long time (Bryant, 2000).

Chronic wounds commonly occur in compromised patients (Bryant, 2000), whose ability to heal is delayed owing to underlying pathological problems, such as vascular disease or diabetes. It has also been suggested that chronic wound fluid, or exudate, inhibits fibroblast growth, which is essential for the synthesis of collagen and formation of healthy tissue (Wysocki, 1996).

Further research suggests that raised levels of proteases in chronic wound fluid could account for the wound failing to heal (Phillips, et al, 1998; Yager, et al, 1997). The proteases are enzymes that can destroy proteins including fibroblasts. They are also able to bind to growth factors, thereby inhibiting them from assisting the healing process. Consequently, it is possible that an increased activity of proteases in chronic wound fluid is what inhibits, or even prevents, the wound progressing through the various stages of healing.

Protease inhibitors
Growth factor stabilisation and protection may be achieved by using protease inhibitors, which are designed to modulate biological molecules such as growth factors to promote wound healing (Veves et al, 2002). One such inhibitor is Promogran - Protease-Modulating Matrix (Johnson & Johnson Wound Care). This relatively new product is used topically and may be considered as a cost-effective treatment for all types of chronic wounds (Cullen, 2001). It is a freeze-dried matrix that is constructed of 55% collagen (a structural protein synthesised by fibroblasts), the main constituent of skin, tendons, ligaments, bones, cartilage, fascia and scar tissue (Westaby, 1995). The other 45% is oxidised regenerated cellulose.

The matrix binds to excess proteases in a wound to deactivate them and, in doing so, protects existing growth factors, allowing them to assist the synthesis of collagen.

Promogran is bio-absorbable, which means it is absorbed directly into the wound bed. It should be applied to an entire, reasonably clean wound, so it is important to remove any devitalised (dead) tissue, such as tenacious yellow slough or black eschar, before application. Without debridement, the healing process cannot start (Baharestani, 1999). The treatment can be applied to surface or cavity wounds, wet or dry, depending on exudate levels. If a wound produces small amounts of exudate, Promogran can be moistened with normal saline to turn it into a gel. A secondary dressing should be applied to keep it in place, preferably one that creates a moist environment, as epithelialisation occurs twice as quickly in moist wounds compared with wounds kept dry by exposure (Winter, 1962).

In cases where a wound is exuding heavily, Promogran can be applied dry to allow the exudate to saturate it and turn it into a gel. Again, a secondary dressing capable of maintaining a moist healing environment should be applied. Promogran should be reapplied every two to three days, depending on the amount of exudate. More frequent dressing changes may be required if the wound is producing excess fluid.

Because Promogran is absorbed directly into the wound, there is minimal, if any, risk of pain or local trauma on dressing changes. A study by Kammerlander and Eberlein (2002) shows that wound-care practitioners perceive prevention of pain and trauma at dressing changes as key objectives, therefore minimising the patients' pain during dressing changes improves their quality of life. This is easily achieved with Promogran because it does not need to be removed at each dressing change - it simply requires another piece to be reapplied to the wound.

Case history
Simon Mather is a 72-year-old artist with a long history of ankylosing spondylitis, a connective tissue disease characterised by inflammation affecting the spine and the joints that connect the spine to the pelvic bones, resulting in stiffness and pain (Merck, 2002).

Many people with ankylosing spondylitis have the condition mildly and simply experience some lower back pain. However, in a small minority of patients the condition will be more advanced. Mr Mather developed an extremely rare complication: his inflamed sacral joints had caused spinal diverticulosis, whereby his intervertebral discs were protruding out of his spine, thus compressing his lumbar and sacral nerves. Loss of nerve reflexes in the ankle is one of the symptoms of this advanced condition, resulting in Mr Mather having complete loss of sensation to the sole of his right foot.

The sequence of events began in April 2001. One of his wife's lipstick cases had fallen into Mr Mather's right shoe. Mr Mather had crushed the lipstick case when he put on his shoe, and because of the loss of sensation, had not realised that he had sustained a puncture wound to his great toe. Gradually, over a few weeks his foot became red, inflamed and the wound began to discharge pus. Because of nerve damage (neuropathy) and Mr Mather's inability to feel painful stimuli he developed a toe infection that progressed into an abscess.

His GP referred him to hospital where he was admitted for a routine incision and drainage of the abscess. Two days later Mr Mather was given one-month supply of oral antibiotics and discharged by the consultant to the care of the community nurses, who dressed the wound with Kaltostat according to the consultant's instructions. However, Mr Mather said the wound was not healing and was in fact getting worse. He was readmitted to hospital with an infected and necrotic web space in August and underwent an inspection under anaesthetic. The consultant was concerned that Mr Mather's great toe might require amputation. Initially a debridement was carried out, although amputation still appeared the best course of action in the long term.

The wound was initially managed in the ward by staff nurses but two weeks later a referral was made to the tissue viability team, as the wound continued to exude heavily and showed no signs of healing. At the initial assessment, the tissue viability nurse thought it would be beneficial to photograph the wound so progress could be monitored (Figures 1 and 1a).

Postoperative instructions to manage the wound were as follows: intravenous antibiotics were administered four times a day, and the wound was to be dressed with povidone-iodine soaked gauze, as advised by the consultant. This was routinely carried out by staff nurses in the ward. The dark staining to the foot on the photograph indicates iodine staining, the wound borders are defined, and it shows no signs of epithelial cell (new tissue) migration across the wound bed.

In addition, owing to the vast amounts of exudate, the skin surrounding the wound had become macerated, indicating deterioration in the wound's condition (Cutting, 1999). Permission to allow the tissue viability nurse to manage the wound was verbally obtained from the patient and the consultant agreed. The tissue viability nurse returned daily to reassess and redress the wound.

The main objective was to manage the wound exudate: this was done by applying a hydrofibre dressing directly to it, then covering this with an adhesive foam secondary dressing. Mr Mather was also receiving a course of prophylactic intravenous antibiotics. The high fluid retention capacity of the hydrofibre would manage the exudate at wound bed level and the secondary dressing would serve to prevent further maceration to the surrounding skin by absorbing the overspill of exudate. It also provided a protective barrier against bacteria. The antibiotic therapy was systemic prophylaxis to prevent further infection and was prescribed by medical staff.

After a week of daily dressing changes it was evident that the wound was still producing vast amounts of exudate; the surrounding skin was still macerated and the adhesive in the absorbent secondary dressing was becoming deactivated by the excessive moisture, causing it to fall off. It was decided to discontinue the regimen and begin using an alternative highly absorbent dressing. This was to be applied over a non-adherent silicone-coated knitted viscose dressing placed at the surface of the wound, to reduce the risk of adherence to the wound bed.

At the end of a second week of daily dressings the exudate became manageable. Signs of healing were observed: healthy pink and white epithelial cells were noticeable around the wound margin and the dimensions of the wound were decreasing (Figure 2).

Mr Mather was discharged and told to return to the tissue viability nurse three times a week for dressing changes using the current regimen, as it appeared to be controlling the exudate and the wound appeared healthy. However, over the next four weeks there was no further progress: the wound was slowly becoming chronic, it appeared slightly macerated, and a stubborn layer of slough had developed in the web space (Figure 3). In addition, a thick callus was forming around the border of the wound (Figure 3a), making it difficult for new epithelium to migrate over the wound edges.

Towards the end of September it was felt that Mr Mather's wound had become chronic and it was at this point that Promogran was introduced - it was claimed to be a new approach to wound care, with indications for use on all chronic wounds. The tissue viability nurse was asked to evaluate the new treatment and, as a result, signed consent was obtained from Mr Mather and a dressing regimen agreed.

He was to have moist Promogran applied to the wound bed, which would then be covered with a small piece of an activated charcoal and silver dressing. This was to be applied because Mr Mather had developed a fungal infection between his toes, which was becoming slightly malodorous. He was also commenced on daily application of an anti-fungal cream. The silver charcoal dressing was an extra measure to keep the wound bed as clean as possible, as the silver component of the dressing has been found to not only minimise surface bacteria (White, 2001), but also fungal pathogens (Wright et al, 1999). The charcoal element of the dressing helped adsorb bacteria and their spores to manage the odour (Coombes, 1981), which was causing concern for Mr Mather.

It was decided to secure the Promogran with an adhesive foam secondary dressing. In addition, compression socks were prescribed to manage the oedema in Mr Mather's foot, caused by a lack of mobility, local infection and general swelling due to tissue trauma, and to minimise the amount of exudate produced by the wound. This procedure was repeated three times a week.

Outcome
At the first dressing change, there were obvious signs of improvement: granular tissue was observed at the wound bed and epithelial cells appeared to be migrating across the edge of the wound; the level of maceration had decreased and the callus was thinning out (Figure 4).

Four weeks into the treatment, the wound had reduced in size and there were obvious signs of a healthy healing wound (Figure 5). It was now to be dressed twice weekly.

Eight weeks after the start of treatment, the compression socks were still being used; although the wound appeared slightly dry in parts, it continued to decrease in size and looked healthy (Figure 6).

Complete wound closure was obtained 13 weeks into the treatment. Mr Mather was discharged from the care of the tissue viability nurse, his great toe was strapped to his second toe and he was followed up in the orthopaedic clinic (Figure 7).

Conclusion
The experience in managing this case highlights the need for continuous reassessment and re-evaluation of complex/chronic wounds, along with the need to modify or change dressing regimens as required. Although Promogran is a relatively new treatment and further clinical evaluations are required to substantiate its effectiveness, there appeared to be noticeable improvement in the rate of healing in this case. This suggests that, along with good wound care, Promogran may be effective in facilitating healing in chronic wounds, thus improving a patient's quality of life, and minimising wound-associated pain, an aspect considered as the primary aims of wound management (Ovens and Fairhurst, 2002).

- The patient's name has been changed

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