A Randomised Longitudinal Study Comparing Topical Negative Pressure Therapy and Hydrocolloid Dressings in Management of Acute Partial Thickness Burn; A Biochemical and Histological Analysis

Abstract

Topical negative pressure therapy (TNP) is known to be beneficial in promoting wound healing and graft take. We aimed to compare its effects to that of standard hydrocolloid dressings on progression and healing of acute partial thickness burns. A longitudinal study was performed in two regional burn centers on patients with partial thickness burns. TNP was compared to a standard hydrocolloid and assessed biochemically and histologically at specific intervals. Dressings were used to create high and low environments. Wounds were analyzed using a collagen disc, created by removing the silicone layer of Integra™ from its collagen component. H&E, Masson' Trichrome (MT) and immunohistochemical staining for CD34, CD45 and a broad cytokeratin stain were performed. ELISA assays were performed on homogenized collagen discs. Analysis for neutrophil elastase (NE), the predominant acute burn protease demonstrated opposing levels in the two wounds with over 200% difference between them at day 5 (p<0.01 - ANOVA and students paired T test). Similar differences were seen in α1 protease inhibitor levels, again achieving statistical significance (p<0.01). Assay for VEGF demonstrated different angiogenic profiles between the opposing wounds (p<0.01). Differences noted in H&E stains were assessed using a broad cytokeratin marker. Cell counts demonstrated a statistically significant difference in cytokeratin positive cells between both wounds (p<0.01 - ANOVA and students paired T test). VAC™ burns resulted in a mean of 75% more cytokeratin positive cells and the cell layer architecture was disrupted compared to hydrocolloid burns. Equivalency of burn depth was confirmed using MT stains. CD34 stains were used to quantify vascular endothelial cells and showed a statistically significant difference between both burns (p < 0.01 - ANOVA and student's paired T test).