INTRODUCTION:

Open wounds have been shown to heal up to 50% more quickly under moist conditions than when dry. A moist healing environment can be facilitated by many available dressings, whose action maintains an acidic pH which can prevent the growth of certain bacteria. These dressings facilitate the transfer of phagocytes, and the action of lysosomal enzymes on the necrotic tissue, increasing granulation and epithelialisation. These dressings do not have an antibacterial effect but maintain the population of both aerobic and anaerobic bacteria at a constant level. The presence of these bacteria does not affect the wound healing process. It therefore is considered good practice to apply a dressing to the leg ulcer wound beneath a compression bandage, to form a warm, moist medium that promotes granulation and epithelialisation. The dressing should be easy to change and should also be relatively inexpensive.The aim of the study was to evaluate and compare two wound dressings - a polyurethane foam dressing and a hydrocolloid dressing - in the treatment of chronic venous ulcers. The assessment of comfort by the patient and ease of application and removal of the

dressings by the nursing staff was also recorded. A high-compression bandage (Setopress) was used with both dressings.

The hydrocolloid dressing is made up of a thin polyurethane foam sheet bonded onto a polyurethane film, which is impermeable to exudate and micro-organisms. The foam is coated with an adhesive mass composed of polyisobutylene and containing hydrophilic particles of gelatin, pectin and carboxymethylcellulose. On contact with wound exudate, these panicles absorb water and swell, forming a gel. This gel then absorbs the exudate and necrotic tissue cells. The dressing can be kept in place for seven days before replacement. The efficacy of this product has been subject to many trials. The polyurethane foam dressing is made up of an internal hydrophilic layer with absorption properties and a hydrophobic external layer of polyurethane foam which acts as a protective material. The dressing absorbs tissue fluids through the hydrophilic wound contact layer and the aqueous component is lost by evaporation through the back of the dressing as moisture vapour. Cellular debris and proteinaceous material are trapped in the small pores of the dressing and a moist, warm environment is maintained at the surface of the wound, thus promoting granulation and healing. This dressing has been shown to be effective in the healing of leg ulcers. The high-compression bandage is made of an advanced lightweight fabric available in two widths. When applied correctly, it produces a high level of compression that has been demonstrated to be effective in the healing of even long-standing leg ulcers within 12 weeks. Rectangles are printed on both sides of the bandage to assist in its application at the correct pressure to achieve healing (40mmHg at the ankle).

Case：

Leg ulcer before treatment (top) and after treatment with polyurethane foam dressings for 14 weeks.(Left)Leg ulcer before treatment (top) and after treatment with hydrocolloid dressings for 16 weeks.(Right)

Discussion:

Efficacy :Table 2 shows the treatment outcomes. The efficacy of the treatment was identical for both groups. At the end of the 16-week treatment period, 60% of the patients treated with polyurethane foam dressings and 60% treated with hydrocolloid dressings had healed (no

statistical significance).

Patients’ comfort and pain on removal:Table 4 shows the results of the patients’ subjective assessment of dressing comfort. The patients were asked to score on a scale of 0-10 (0 = uncomfortable and 10 = very comfortable) according to whether they felt the dressings were comfortable while in place. Both dressings were highly rated by the patients, with a slight preference shown for the polyurethane foam dressing (no statistical significance). Patients were also asked if their dressings caused any pain on removal (scale of 1-4 where 1 = very painful and 4 = no pain). Again, both dressings were highly rated by the patients with a slight preference shown for the polyurethane foam dressing (no statistical significance). Patients commented on the ease of removal of the dressings.Ease of application and removal :Both dressings were easy to apply as judged by the nurses on a scale of 0- 10 where 0 = easy to apply and 10 = difficult to apply. No statistical significance between the groups was found (Table 5). However, the polyurethane foam dressing was rated as easier to remove than the hydrocolloid dressing (scale of 0 = 10, 0 = easy and 10 = difficult; statistically significant at 5%, p=0.016).

Conclusion:

When applied under a compression bandage, both the polyurethane foam dressing and the hydrocolloid dressing showed high efficacy in the healing of leg ulcers. The results of treatment and the process of healing were similar for both products, with 80% of patients in both groups showing a significant improvement or total healing of the ulcer. Complications of secondary infection and maceration occurred. There were eight cases of streptococcal cellulitis which required antibiotic treatment; two patients were withdrawn from the trial as a result. The same number of patients were affected in each group. Both dressings were found to be comfortable, caused little pain on removal and were easy to apply. The polyurethane foam dressing was significantly easier to remove from the wound than the hydrocolloid dressing. The efficacy of both dressings combined with a high degree of comfort, infrequent dressing changes, and the ability to wear normal footwear are in agreement with previous reports.

Bowszyc, J., et al. "Comparison of two dressings in the treatment of venous leg ulcers." Journal of Wound Care 4.3 (1995): 106-110.