Severe Burn Injury in a Swine Model for Clinical Dressing Assessment

To closely mimic the mode of burn injuries requires the interplay between clinical observation and studies in animal models. In this study, a swine model of severe burn injury was established to assess an experimental dressing in physiological and pathophysiological settings.

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This method can help answer key questions in the burn injury field about warfare wound handling or how to treat burn wounds after fire accident. The main advantage of this swine burn injury model is the degree of similarity between the anatomical and the physiological structure of pig and human skin tissue. Though this method can provide insight into the effects of calcium alginate polysaccharide dressings on burn wound healing, it can also be applied to studies of burn management.

Before delivering the burn, shave and moisture an approximately 25-centimeter-wide area of skin from the vertebral column all the way to the axilla on both sides of the spine of an anesthetized adult pig. Then, scrub the exposed skin with povidone-iodine for approximately five minutes. Use wet sterile gauze to remove the povidone-iodine soap, and sterilize the clean skin with povidone-iodine lotion.

And use a surgical marking pen to demarcate the center of six burn wound locations on the dorsum of the animal. Then, cover the animal with sterile surgical drapes, taking care that the distance between each area is at least greater than the radius of the area. When all of the areas have been marked, fill a modified soldering iron equipped with an approximately nine square centimeter flat area with 50 milliliters of glycerin, and insert an electronic thermometer into the iron to monitor the temperature.

After heating the iron to 137 to 139 degrees Celsius on a hot plate, gently press the iron onto each marked area for 30 seconds per area to create six uniform burn wounds. When the heated iron touches the skin, the heat will immediately dissipate across the surface of burnt area, so be sure to preheat the iron and the glycerin for at least 10 minutes before applying the burns. Then, wash the wounds with 0.9%saline solution, and measure and record the wound dimensions by photomicrography.

When all the wounds have been measured, apply the dressings directly onto each wound, followed by the application of a waterproof film over the inner dressing layer to serve as a barrier against bacterial penetration. Then, tape a 5-centimeter-thick piece of gauze over each wound to serve as the mid-layer of the dressing, and secure the gauze with an outer layer of adhesive plaster, extending the plaster to the torso to avoid displacement of the dressing. Change the clinical dressings every two days for the first 10 days, then twice a week until day 42, cleaning and measuring the wounds according to the Vancouver Scar Scale before each dressing reapplication.

Swab the wound for antibacterial testing on post-burn days zero, seven, 21, and 42, and place the swabs in 100 milliliters of 0.9%sterile saline solution. Gently vortex the swabs to obtain a homogenous suspension, and serially dilute the resulting cell solution. Then, plate 100 microliters of each dilution in selective or nonselective medium, and incubate the wound culture under aerobic conditions at 37 degrees Celsius for 24 to 72 hours.

At the end of the incubation, plate 10-microliter aliquots from each dilution culture in triplicate onto blood agar plates supplemented with 5%sheep blood for overnight culture at 37 degrees Celsius. The next morning, use a marker and a small ruler to divide the bottom of each dish into four equal quadrants, and determine the number of colony-forming units in each quadrant under a dissecting microscope. In this representative experiment, burn wounds re-epithelialization was evaluated by gross inspection on post-burn day 42.

A significant reduction in wound area was observed compared to day zero. The healing rate was defined as the greatest average wound margin distance from the wound center divided by the time to complete wound closure, demonstrating over 73%wound closure on post-burn day 42. The Vancouver scar scores peaked on post-burn day 21 and decreased to below the initial wound size by post-burn day 42.

Histologic examination of skin samples harvested on day 42 confirmed that full-thickness burns were achieved and that the wounds appeared to be fully healed. Necrosis resulting from burns could be observed in the epidermis, dermis, and dermal components of the wound without significantly affecting the underlying muscle. The thickness beneath the experimental dressing was 5.4 millimeters, and dermal sloughing and lymphocytic infiltration were observed.

Bacterial cultures of wound swabs collected on post-burn days zero, seven, 21, and 42 demonstrated a slight increase in colony-forming units from days zero to 21 that were significantly increased on day 42, confirming that this swine model of severe burn injury can be used for monitoring the clinical performance of experimental dressings. While attempting this procedure, it's important to remember to know how to handle the animal and then to properly monitor the animal's vital sign during the evental period. Following this procedure, other methods like bacterial growth experiments can be performed to answer additional questions about how natural polysaccharide materials work in cases of severe burn injury.

After its development, this technique paved the way for researchers in the field of burn wound healing to explore the effects of natural calcium alginate polysaccharide dressings in human skin healing. Don't forget that working with heated iron and glycerine can be extremely hazardous and that precautions such as functioning equipment should always be taken while performing the procedure.

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Journal (Medicine)

Journal (Medicine)

Severe Burn Injury in a Swine Model for Clinical Dressing Assessment

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