The Effects of Epidermal Debridement of Partial‐thickness Burns on Infection and Reepithelialization in Swine

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Background A major potential goal of burn therapy is to limit progression of partial to full-thickness) burns. To better test therapies, we developed and validated a vertical progression porcine burn model in which partial thickness burns treated with an occlusive dressing convert to full thickness burns that heal with scarring and wound contraction. Methods Forty contact burns were created on the backs and flanks of two young swine using a 150 gm aluminum bar preheated to 70°, 80°, or 90°Celsius for 20 or 30 seconds. The necrotic epidermis was removed and the burns were covered with a polyurethane occlusive dressing. Burns were photographed at 1, 24, and 48 hours as well as at 7, 14, 21, and 28 days post injury. Full thickness biopsies were obtained at 1, 4, 24, and 48 hours, as well as at 7 and 28 days. The primary outcomes were presence of deep contracted scars and wound area 28 days after injury. Secondary outcomes were depth of injury, reepithelialization, and depth of scars. Data were compared across burn conditions using ANOVA and χ2 tests. Results Eight replicate burns were created with the aluminum bar using the following temperature/contact-time combinations: 70/20, 70/30, 80/20, 80/30, and 90/20. The percentage of burns healing with contracted scars were 70/20–0%, 70/30–25%, 80/20–50%, 80/30–75%, and 90/20–100% (P=0.05). Wound areas at 28 days by injury conditions were 70/20–8.1 cm2, 70/30–7.8 cm2, 80/20–6.6 cm2, 80/30–4.9 cm2, and 90/20–4.8 cm2 (P=0.007). Depth of injury judged by depth of endothelial damage for the 80/20 and 80/30 burns at 1 hr was 36% and 60% of the dermal thickness respectively. The depth of injury to the endothelial cells 1 hour after injury was inversely correlated with the degree of scar area (Pearson’s correlation r=−0.71, P<0.001). Conclusions Exposure of porcine skin to an aluminum bar preheated to 80°C for 20 or 30 seconds results initially in a partial thickness burn that when treated with an occlusive dressing progresses to a full thickness injury and heals with significant scarring and wound contracture.

Section: Methodsmentioning

confidence: 99%

Validation of a Vertical Progression Porcine Burn Model

Singer

Hirth

McClain

et al. 2011

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“…Results of an experiment using the pig model showed increased infection rates in débrided blister wounds when compared with intact blister wounds in partial-thickness burns. 49 However, the method of wound management after blister débridment was the application of dry dressings, which is no longer considered standard of care for this type of wound. Thus, the findings of this study are difficult to transfer to practice.…”

Section: Infectionmentioning

confidence: 99%

Management of Blisters in the Partial-Thickness Burn: An Integrative Research Review

Sargent

2006

Conflicting recommendations and clinical applications have been given concerning best practices for the management of burn blisters associated with partial-thickness burns. Arguments for the preservation of intact blisters center on the idea of naturally occurring biologic protection whereas the débridment of blisters has been advocated because of the perceived decreases in wound infection and complications. Recurring themes in burn wound management that are considered in this debate include infection, healing, functional and aesthetic outcome, patient comfort, ease of dressing care, and cost efficiency. The management of burn blisters should be supported by evidence across these six categories, should match the expertise of the provider, and should use the available resources in the practice setting. The purpose of this review is combine the findings of a comprehensive review of the published literature with respect to the management of blisters in the partial-thickness burn into a clinical guideline for best practice based on available evidence.

“…Removal of the necrotic epidermis results in delayed reepithelialization and increased scar formation. 10 Sixteen burns were inflicted on each of three pigs (evenly distributed between both side of the pigs), for a total of 48 burns.…”

Section: Burn Model and Experimental Protocolmentioning

confidence: 99%

Lack of Agreement Between Gross Visual and Histological Assessment of Burn Reepithelialization in a Porcine Burn Model

Singer

Hirth

McClain

et al. 2012

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One of the most important and earliest measures of burn healing is wound reepithelialization. Reepithelialization is a vital determinant of wound infection and scarring. Reepithelialization is generally based on gross visual assessment; however, histological assessment remains the criterion standard. We hypothesized that there would be poor agreement (r < .4) between gross visual and histological assessments of burn reepithelialization in a porcine model. The study design was prospective observational using three anesthetized female pigs (20-25 kg). Forty-eight 2.5- × 2.5-cm burns were created on the flanks of pig's using an aluminum bar (150 g) preheated to 80°C for 20 seconds. Burns were treated with an occlusive or antimicrobial dressing and photographed at day 10 for determination of gross percentage reepithelialization in a 1-cm diameter circle in the center of the burn by two experienced clinicians masked to each other's measurements. A 10-mm full-thickness punch biopsy was taken from the center of the burns and evaluated by a board-certified dermatopathologist masked to clinical assessments. One clinician and the dermatopathologist repeated the assessments 1 month apart. The outcome was percentage wound reepithelialization at 10 days. The criterion standard was the histological assessment. Intraobserver and interobserver agreements were calculated with Pearson's correlation coefficients. A coefficient less than .4 was considered poor. Sixteen burns were created on each of three animals. Six wounds were excluded because of the presence of a thick eschar covering the burn, making the gross determination of reepithelialization impossible. Intraobserver agreement for histological reepithelialization was 0.96 (P < .001). Intraobserver agreement for gross visual assessment of reepithelialization was 0.75 (P < .001). Interobserver agreement for gross visual assessment of reepithelialization was 0.60 (P < .001). The agreement between gross visual and histological assessment of burn reepithelialization was -0.25. Although there was a good interobserver agreement for gross visual assessments, there was a poor agreement between gross visual and histological assessments of burn reepithelialization. Care should be used when determining burn reepithelialization based on gross visual assessments alone.