Novel burn device for rapid, reproducible burn wound generation

Abstract

Introduction Scarring following full thickness burns leads to significant reductions in range of motion and quality of life for burn patients. To effectively study scar development and the efficacy of anti-scarring treatments in a large animal model (female red Duroc pigs), reproducible, uniform, full-thickness, burn wounds are needed to reduce variability in observed results that occur with burn depth. Prior studies have proposed that initial temperature of the burner, contact time with skin, thermal capacity of burner material, and the amount of pressure applied to the skin need to be strictly controlled to ensure reproducibility. The purpose of this study was to develop a new burner that enables temperature and pressure to be digitally controlled and monitored in real-time throughout burn wound creation and compare it to a standard burn device. Methods A custom burn device was manufactured with an electrically heated burn stylus and a temperature control feedback loop via an electronic microstat. Pressure monitoring was controlled by incorporation of a digital scale into the device, which measured downward force. The standard device was comprised of a heat resistant handle with a long rod connected to the burn stylus, which was heated using a hot plate. To quantify skin surface temperature and internal stylus temperature as a function of contact time, the burners were heated to the target temperature (200 ± 5 °C) and pressed into the skin for 40 s to create the thermal injuries. Time to reach target temperature and elapsed time between burns were recorded. In addition, each unit was evaluated for reproducibility within and across three independent users by generating burn wounds at contact times spanning from 5 to 40 s at a constant pressure and at pressures of 1 or 3 lbs with a constant contact time of 40 s. Biopsies were collected for histological analysis and burn depth quantification using digital image analysis (ImageJ). Results The custom burn device maintained both its internal temperature and the skin surface temperature near target temperature throughout contact time. In contrast, the standard burner required more than 20 s of contact time to raise the skin surface temperature to target due to its quickly decreasing internal temperature. The custom burner was able to create four consecutive burns in less than half the time of the standard burner. Average burn depth scaled positively with time and pressure in both burn units. However, the distribution of burn depth within each time-pressure combination in the custom device was significantly smaller than with the standard device and independent of user. Conclusions The custom burn device's ability to continually heat the burn stylus and actively control pressure and temperature allowed for more rapid and reproducible burn wounds. Burns of tailored and repeatable depths, independent of user, provide a platform for the study of anti-scar and other wound healing therapies without the added variable of non-uniform starting injury.

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

“…(mean, 0.077 in.). Thermal injury was induced using our previously reported custom burn device . The stainless steel stylus (5 cm × 5 cm) was heated to 200 ± 10 °C and was pressed to the surface of the skin for 40 seconds at a pressure of three pounds.…”

“…Thermal injury was induced using our previously reported custom burn device. 21 The stainless steel stylus (5 cm 3 5 cm) was heated to 200 6 10 8C and was pressed to the surface of the skin for 40 seconds at a pressure of three pounds. To examine the initial depth of burn injury, biopsies were collected from select burn wounds immediately after injury.…”

Comparing the reported burn conditions for different severity burns in porcine models: a systematic review

“…A major concern regarding the use of porcine burn models is the challenge of creating reproducible burns of the same depth and severity. Numerous investigators have published porcine burn models, describing the burn conditions required to create a desired depth or severity of injury . The various strengths and weaknesses of the different techniques and reproducibility of burn creation have been described previously .…”

Thermal injury model in the rabbit ear with quantifiable burn progression and hypertrophic scar

“…Contact burns with preheated brass showed variability, which could be due to the curvature of the rabbit ear, regional skin thickness differences in the rabbit ear, or inadequate or inconsistent heating of the rods. This model may benefit from a burn device which provides a more controlled burn, such as new devices designed to control heat transfer and pressure throughout the burn . This model is not suited to studying systemic immune dysregulation related to burns due to the small size of the burns, however, it is well suited to studying the effects of therapeutic agents as early interventions to burn progression and scar formation.…”