Immediate Burn Excision Fails to Reduce Injury Progression

Abstract

The contact thermal injury model in the pig was used to determine whether immediate burn excision could alter the extent of injury progression. It was hypothesized that immediate excision of burns would prevent or reduce tissue necrosis in the uninjured interspaces. Four comb burns were created on the back of each animal, using a brass comb preheated in hot water (100 °C) for 5 minutes. This brass comb produced four distinctive burns sites separated by three "interspaces" of unburned skin, which were to undergo progressive injury. Immediately after burn creation, half of the full-thickness burns were excised leaving the unburned interspaces intact. Two full-thickness excisional wounds per pig with the dimensions identical to the comb burns were included as controls. Burn injury progression was microscopically assessed and reported as the percentage of unburned interspaces that progressed to full-thickness necrosis 7 days after injury. Scar formation was grossly evaluated on day 28 after injury and reported as the total surface area (in square centimeters) of the scar. A total of 24 combs with 72 interspaces were evenly distributed among the three groups. The unburned interspaces of both comb burns and excised comb burns had undergone progressive injury and were 100% dead (24/24; i.e., necrotic and/or apoptotic) 7 days postinjury (95% confidence interval, 86-100%) for both. However, interspaces of the control excisional wounds maintained complete viability, that is, no necrosis or apoptosis (0/24 [0%]; 95% confidence interval, 0-14%; P < .001). There was no significant difference in both surface area and depth of scar resulting from excised and nonexcised comb burns. Immediate burn excision neither prevented nor limited burn injury progression.

Scar formation following excisional and burn injuries in a red Duroc pig model

“…The increased time to heal in the burn wounds was expected as the initial injury is more significant, not only destroying the tissue immediately beneath the burn stylus (with accompanying persistence of nonviable tissue) but also triggering a cascade of events in the surrounding tissue that can lead to damage in the area surrounding the contact region. Previous work with female domestic pigs by Macri et al utilized a comb burn model where four contact burns were made, separated by 5 × 20 mm unburned “interspaces,” and either left to heal or excised to the wound margins . In both cases, the interspaces were 100% necrotic and/or apoptotic within 7 days of injury .…”

“…Previous work with female domestic pigs by Macri et al utilized a comb burn model where four contact burns were made, separated by 5 × 20 mm unburned “interspaces,” and either left to heal or excised to the wound margins . In both cases, the interspaces were 100% necrotic and/or apoptotic within 7 days of injury . This was contrasted with control wounds having the same dimensions as the comb burner but created by excising unburned skin; in this case, interspaces remained viable and supported improved healing and scarring over burn injuries.…”

Current concepts on burn wound conversion—A review of recent advances in understanding the secondary progressions of burns

“…The majority of articles addressed better studied concepts such as ischemia (9 studies) and inflammation (6 studies), whereas more recently discovered mechanisms such as autophagy (3 articles) had less focus, as expected. Articles grouped under “other” included studies on stem cell therapies [15, 16], enzymatic wound debridement [17], burn excision [18] and hyperbaric oxygen treatment (HBOT) [19]. We found that most studies on burn wound progression over the last five years involved experimental treatments in animal models, and very few studies were solely focused on further elucidating the mechanisms behind burn wound conversion (Fig.…”

“…That being said, several studies in this review investigated alternative methods to prevent secondary necrosis. Two studies examined the adaption of conventional methods of local treatment of burn wounds, particularly wound debridement [18] and burn excision [17], in the context of burn conversion. Singer et al .…”

“…Singer et al . evaluate the ability of a novel bromelin-based enzymatic preparation in salvaging tissue in the zone of stasis after immediately applying the compound to exposed dermis in burn wounds [18]. While animals with enzymatic debridement of eschar had significantly less interspace tissue necrosis in the burn comb model, two-thirds of the experimental group still exhibited partial-thickness necrosis of the zone of stasis and the remaining one-third had full-thickness necrosis.…”