160 The Selective Anti-Inflammatory Activity of Prolonged Release Nanocrystalline Silver Dressing (Acticoat 7®) in the Treatment of Chronic Venous Leg Ulcers

Abstract

The treatment of venous ulcers must start with compression and if the ankle brachial index is greater than 0.8 high compression bandages can be applied. Despite edema control, there are a number of venous ulcers that do not heal at the expected rate. Patients with venous ulcers of greater than 4 weeks duration were treated with a prolonged release absorptive nanocrystalline silver dressing (Acticoat 7) under the 4 layer bandage, Profore for 12 weeks, or until healing. Biopsies were obtained from the ulcer base at week 0 for histology and bacterial burden. Duplicate biopsies for quantitative bacteriology were performed with one submitted whole and the second bisected into superficial and deep components. The paired biopsies were then repeated after a median of 6.5 weeks (range 2 to 12 weeks). The histological specimens were examined by the histopathologist (SR). Inflammatory infiltrates were identified in the superficial, middle and deep segments of the biopsies. Acute infiltrates were identified through the concentration of neutrophils and chronic infiltrates by the presence of lymphocytes. Each biopsy and each segment was graded for infiltrates on a four point semi quantitative score. A total of 15 patients (9 male, and 6 female) were enrolled into the study. The median age was 63 years (range 30–83 years). The median duration of current ulceration was 17.3 weeks (range 4 weeks to 11 years) and the median ulcer area was 4.8 cm2(range 1.8–43.9 cm2). The median exposure to Acticoat 7 was 82 days (range 8–86 days). There were 12 sets of paired biopsies that were analyzed. There was a statistically significant reduction (p = 0.0114) in the log10(total bacterial count) between the baseline and final biopsies (median 4.48 and 3.00, respectively). Four patients healed, 8 patients continued to the end of the 12-week study period and three patients were discontinued early. For all patients, the median percentage reduction in ulcer area was 94.4% and the median final ulcer area was 0.4 cm2. Analysis of the histology and bacteriology data demonstrated that the presence of a high neutrophilic infiltrate in skin biopsies was associated with high bacterial counts (superficial compartment of the quantitative biopsies) at week 4 and delayed healing (p = 0.037). In the week 0 biopsy, increased lymphocytic infiltrates within the superficial and middle segments were associated with accelerated healing in the first 4 weeks (p = 0.26 and 0.09). The nanocrystalline silver dressing has demonstrated an anti-bacterial and permissive but selective anti-inflammatory action allowing lymphocytic infiltrates to increase associated with an accelerated reduction in ulcer size.