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Introduction: Platelet rich plasma (PRP) is rich in growth factors and has been shown to improve healing in a variety of wounds. We determined the effects of PRP on healing and scarring in full thickness porcine burns with and without tangential excision and grafting (TEG)., Methods: Standardized full thickness 5cm by 5cm burns were created on each of the backs and flanks of 10 anesthetized female pigs (25kg) using a validated model. The burns were created with a heating device that emits heat at a temperature of 400°C for a period of 30s. The burns were randomized to one of six treatments: no TEG or PRP, no TEG+PRP, early (day 2) TEG and no PRP, early TEG+PRP, late (day 14) TEG and no PRP, and late TEG+PRP. Tangential excision was performed down to viable tissue and autografts were 0.2mm thick. When used, a thin layer of autologous PRP was applied below the graft. All wounds were then treated with a topical antibiotic ointment 3 times weekly for 42 days. Digital images and full thickness biopsies were taken at 9, 11, 14, 18, 21, 28, 35 and 42days after injury to determine percentage reepithelialization, scar depth, and scar contraction. Tissue sections were stained with H&E and viewed by a dermatopathologist masked to treatment assignment., Results: There was no reduction in platelet and white blood cell concentrations in PRP and blood samples for the first 14days after-full thickness burns. A total of 120 burns were created on 10 animals evenly distributed between the six treatment groups. Burns undergoing early TEG reepithelialized fastest and with the thinnest scars followed by late TEG. Burns that did not undergo TEG had the slowest reepithelialization and greatest amount of scarring. Application of PRP had no additional effects on reepithelialization, scar depth, or scar contraction in any of the treatment groups., Conclusions: Addition of PRP had similar effects on reepithelialization and scarring of full thickness porcine burns as standard topical antibiotic ointment regardless of whether the burns underwent excision or grafting or the timing of excision and grafting., (Copyright © 2018 Elsevier Ltd and ISBI. All rights reserved.)

Introduction: Current methods of assessing burn depth are limited and are primarily based on visual assessments by burn surgeons. This technique has been shown to have only 60% accuracy and a more accurate, simple, noninvasive method is needed to determine burn wound depth. Forward-looking infrared (FLIR) thermography is both noninvasive and user-friendly with the potential to rapidly assess burn depth. The purpose of this paper is to determine if early changes in burn temperature (first 3 days) can be a predictor of burn depth as assessed by vertical scarring 28 days after injury., Methods: While under general anesthesia, 20 burns were created on the backs of two female Yorkshire swine using a 2.5cm×2.5cm×7.5cm, 150g aluminum bar, for a total of 40 burns. FLIR imaging was performed at both early (1, 2 and 3 days) and late (7, 10, 14, 17, 21, 24 and 28 days) time points. Burns were imaged from a height of 12 inches from the skin surface. FLIR ExaminIR(©) software was used to examine the infrared thermographs. One hundred temperature points from burn edge to edge across the center of the burn were collected for each burn at all time points and were exported as a comma-separated values (CSV) file. The CSV file was processed and analyzed using a MATLAB program. The temperature profiles through the center of the burns generated parabola-like curves. The lowest temperature (temperature minimum) and a line midway between the temperature minimum and ambient skin temperature at the burn edges was defined and the area of the curve calculated (the "temperature half-area")., Results: Half-area values 2 days after burn had higher correlations with scar depth than did the minimum temperatures. However, burns that became warmer from 1 day to 2 days after injury had a lower scar depth then burns that became cooler and this trend was best predicted by temperature minima. When data were analyzed as a diagnostic test for sensitivity and specificity using >3mm scarring, i.e. a full-thickness burn, as a clinically relevant criterion standard, temperature minima at 2 days after burn was found to be the most sensitive and specific test., Conclusions: FLIR imaging is a fast and simple tool that has been shown to predict burn wound outcome in a porcine vertical injury progression model. Data showed that more severe burn wounds get cooler between 1 and 2 days after burn. We found four analytic methods of FLIR images that were predictive of burn progression at 1 and 2 days after burn; however, temperature minima 2 days after burn appeared to be the best predictive test for injury progression to a full-thickness burn. Although these results must be validated in clinical studies, FLIR imaging has the potential to aid clinicians in assessing burn severity and thereby assisting in burn wound management., (Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.)

Introduction: In order to be useful, animal models should be reproducible and consistent regardless of sampling bias, investigator creating burn, and burn location. We determined the variability in burn depth based on biopsy location, burn location and investigator in a porcine model of partial thickness burns., Methods: 24 partial thickness burns (2.5 cm by 2.5 cm each) were created on the backs of 2 anesthetized pigs by 2 investigators (one experienced, one inexperienced) using a previously validated model. In one of the pigs, the necrotic epidermis covering each burn was removed. Five full thickness 4mm punch biopsies were obtained 1h after injury from the four corners and center of the burns and stained with Hematoxylin and Eosin and Masson's trichrome for determination of burn depth by a board certified dermatopathologist blinded to burn location and investigator. Comparisons of burn depth by biopsy location, burn location and investigator were performed with t-tests and ANOVA as appropriate., Results: The mean (SD) depth of injury to blood vessels (the main determinant of burn progression) in debrided and non-debrided pigs pooled together was 1.8 (0.3)mm, which included 75% of the dermal depth. Non-debrided burns were 0.24 mm deeper than debrided burns (P<0.001). Burn depth increased marginally from cephalic to caudal in non-debrided burns, but showed no statistical differences for these locations, in debrided burns. Additionally, there were also no statistical differences in burn depths from midline to lateral in either of these burn types. Burn depth was similar for both investigators and among biopsy locations., Conclusions: Burn depth was greater for caudal locations in non-debrided burns and overall non-debrided burns were deeper than debrided burns. However, burn depth did not differ based on investigator, biopsy site, and medial-lateral location., (Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.)

Objective: To compare the effects of octylcyanoacrylate (OCA), silver sulfadiazine (SSD), polyurethane film (PU), and dry gauze (G) on scarring three months after partial-thickness burns., Methods: This was a prospective, blinded, controlled experimental trial using isoflurane-anesthetized swine. Standardized partial-thickness burns were inflicted by applying an aluminum bar preheated to 80 degrees C to the backs and flanks of a young pig for 20 seconds. Four equal sets of ten burns each were randomly treated with OCA spray, SSD, PU, or G. Dressing changes were performed on days 1, 2, 3, and 4 after injury. Digital images of the burns were obtained immediately and three months later for masked computerized determination of scar surface area. Full-thickness biopsies were taken at three months for masked histopathological evaluation. The primary outcome was the percent reduction in residual wound area (RWA) calculated by subtracting the area of each individual burn from the area of the largest burn and dividing this value by the area of the largest burn (intraobserver correlation, r = 0.99). Secondary outcomes were the proportion of burns with the presence of scar tissue (abnormal collagen under polarized light; intraobserver agreement, kappa = 0.93) and the cosmetic appearance on a 100-mm visual analog scale marked "best scar" at the high end (inter-observer correlation, r = 0.82). Analysis of variance (ANOVA) and chi(2) tests were used for group comparisons as appropriate. This study had 80% power to detect a 33-percentage-point difference in RWA among groups (alpha = 0.05)., Results: A total of 40 burns were inflicted on the pig. There was no difference in percent RWA across the groups (OCA = 25%, SSD = 40%, PU = 25%, G = 32%; p = 0.13). There was no difference in the proportion of wounds with scarring among the groups (OCA = 10%, SSD = 22%, PU = 2%, G = 30%; p = 0.89). There was also no difference in the cosmetic scores among the groups (OCA = 78 mm, SSD = 75 mm, PU = 74 mm, G = 74 mm; p = 0.96)., Conclusions: The effects of OCA spray, SSD, PU, and dry gauze on scarring three months after burns in pigs are similar.

Objective: Cutaneous wound healing in adults invariably results in scarring; however, there are few scales to quantify the degree of such scarring. The authors developed a histomorphologic scale for quantifying scarring after cutaneous burn injury., Methods: As part of a randomized trial comparing a variety of burn therapies, 40 partial-thickness burns were created on the backs and flanks of anesthetized pigs and treated with a tissue adhesive, antibiotic ointment, occlusive dressing, or dry gauze. Gross scar appearance was independently assessed by two investigators at 90 days on a 100-mm visual analog scale (VAS) marked "best appearance" at the high end. One of the investigators repeated the observation 30 days later. Full-thickness biopsies were taken 90 days after injury and evaluated histologically by a dermatopathologist for the presence of hyperkeratosis, epidermal hyperplasia, presence and depth of scar (defined as abnormally oriented collagen under polarized light), fibroplasia, vascular proliferation, and absence of adnexa, including hair follicles, apocrine glands, and smooth muscles. One point was assigned for each category in the presence of a normal finding, whereas an abnormal finding was assigned a score of zero. The normal dermis (absence of abnormal collagen) was given a score of 3, while decreasing scores of 2 to 0 were given for progressively deeper scars (i.e., 2 for papillary dermis, 1 for upper half of reticular dermis, and 0 for deep dermal lower half). The total histomorphologic score was derived by adding the scores on the individual items. The score ranges from 0 to 10 from worst scarring to absence of scarring, respectively. A subset of observations was evaluated a second time by one of the observers one month later. Intraobserver reliability of the histomorphologic scale was assessed with Spearman's correlation. Inter- and intraobserver Pearson's correlations for the gross scar VAS were calculated, and the correlation between gross and histomorphologic scores was assessed., Results: Intraobserver correlation for individual histomorphologic categories ranged from 0.19 to 1.00. Intraobserver correlation for the total histologic score was 0.95. Inter- and intraobserver correlations for the gross scar VAS were 0.8 each. Correlation between the histomorphologic scale and the gross scar VAS was 0.38., Conclusions: A new reliable histomorphologic method for quantifying and scoring cutaneous scars is described together with a reliable scar VAS. However, these two scales are not highly correlated.

In order to determine whether the enhanced reepithelialization of second-degree burns treated with octylcyanoacrylate (OCA) was due to its occlusive nature we compared reepithelialization (REP) and infection rates of second degree burns treated with OCA and polyurethane film (Tegaderm) in swine. Forty-four standardized partial thickness burns were created by applying an aluminum bar preheated to 80 degrees C to the backs of pigs for 20 s and randomly treated with OCA or Tegaderm. Full thickness biopsies were taken at 7, 10 and 14 days for blinded histopathological evaluation of rates of infection and reepithelialization. T-tests and chi(2) tests were used for group comparisons. There were no between group difference in the rates of reepithelialization and infection. All wounds were reepithelialized by day 14 and there were no infections in either group. We conclude that treatment of partial thickness burns with OCA spray or Tegaderm results in similar rates of reepithelialization and infection, suggesting that the beneficial effects of OCA on reepithelialization are due to its occlusive nature.

Objective: To compare infection and reepithelialization rates of contaminated second-degree burns treated with octylcyanoacrylate (OCA), silver sulfadiazine (SSD), polyurethane (PU) film, and dry gauze (control; C) in swine., Methods: Eighty standardized burns were created by applying an aluminum bar preheated to 80 degrees C to the backs and flanks of young pigs for 20 seconds. All burns were immediately contaminated with 0.1 mL of Staphylococcus aureus 10(5)/mL and randomly treated with OCA spray, SSD, PU, or dry gauze (C). Full-thickness biopsies were taken at 3, 7, and 14 days for blinded histopathologic evaluation using hematoxylin and eosin (H&E)-stained slides. Burns were considered infected in the presence of interstitial reticular dermal neutrophils containing bacteria (intraobserver agreement, kappa = 1.00). Quantitative wound cultures were performed on a second day-3 specimen., Results: At day 3, wound infection rates were 30% (OCA), 50% (SSD), 55% (PU), and 50% (C); p = 0.40 (Kruskal-Wallis test). At day 7, infection rates were 35% (OCA), 85% (SSD), 70% (PU), and 65% (C); p = 0.01. Median bacterial counts at day 3 were 6,500 (OCA), 20,000 (SSD), 1,000,000 (PU), and 650,000 (C); p = 0.29. The proportion of completely reepithelialized wounds at day 14 were 75% (OCA), 90% (SSD), 85% (PU), and 90% (C); p = 0.50., Conclusions: Treatment of contaminated partial-thickness burns with OCA spray resulted in fewer infections at one week than with the other three treatments.

Objective: Early postburn debridement of burn blisters is controversial. This study was conducted to compare rates of infection and reepithelialization in debrided vs nondebrided second-degree burns in swine., Methods: This was a prospective, blinded, controlled, experimental trial using isoflurane-anesthetized swine. Standardized partial-thickness burns were inflicted by applying an aluminum bar preheated to 80 degrees C to the backs and flanks of two young pigs for 20 seconds. In half of the burns the necrotic epidermis was manually debrided. All burns were randomly treated with octylcyanoacrylate spray (OCA) or dry gauze (C). Full-thickness biopsies were taken at 7, 10, and 14 days for blinded histopathologic evaluation. The primary outcomes were the proportions of infected burns at days 7 and 10 and the proportion of completely reepithelialized burns at day 14. Burns were considered infected in the presence of intradermal neutrophils containing bacteria (intraobserver agreement, K = 1.00). A secondary outcome was the proportion of burns with the presence of scar tissue (abnormal collagen under polarized light; intraobserver correlation, K = 0.93). Chi-square tests were used for group comparisons. This study had 90% power to detect a 40-percentage-point difference in infection rates (alpha = 0.05)., Results: A total of 126 biopsies from 42 burns were available for review. Infection rates were higher in the debrided burns both at day 7 (55% vs 4.5%, p < 0.001) and at day 10 (65% vs 9%, p < 0.001) after injury. The proportion of nondebrided burns that were completely reepithelialized was higher at days 10 (68% vs 0%, p < 0.001) and 14 (100% vs 65%, p = 0.003). The presence of scar tissue was more common in debrided burns (75% vs 4.5%, p < 0.001). Burns treated with OCA had fewer infections than controls (4% vs 55%, p < 0.001). Fewer OCA-treated debrided burns were reepithelialized at 14 days than those that were not debrided (30% vs 100%, p = 0.001)., Conclusions: Under the current study conditions, early postburn epidermal debridement of second-degree burns resulted in more infections and slower reepithelialization rates in swine. The effects of early postburn epidermal debridement in humans should be explored.

Objective: Burn depth and extent determine prognosis and therapy. The current classification into first-, second-, and third-degree burns is crude, making comparisons between studies difficult. The authors standardized a reproducible burn model and a precise histopathologic method for describing burn depth in swine., Methods: This was a prospective, cross-sectional interventional animal study. Eighteen paired sets of burns were inflicted on the clipped flank skin of two anesthetized domestic pigs with a 2.5 cm by 2.5 cm by 7.5 cm aluminum bar preheated in water to 50 degrees C, 60 degrees C, 70 degrees C, 80 degrees C, 90 degrees C, degrees C or 100 degrees C. The bar was applied for 10, 20, or 30 seconds. Full-thickness skin biopsies were obtained 30 minutes after injury for blinded histopathologic evaluation using hematoxylin and eosin staining. Two dermatopathologists made two sets of measurements and were masked to each other's evaluations. The depth of injury was measured with an ocular microtome for each of five dermal parameters: collagen discoloration, intercollagen basophilic material, endothelial cell necrosis, epithelial cell necrosis, and mesenchymal cell necrosis. The correlation between burn depths of the paired sets of experiments was calculated to assess the reliability of the model. Inter- and intraobserver correlations were calculated to assess the reliability of the scale. Analysis of variance (ANOVA) was used to assess the relation between temperature and exposure times on burn depth., Results: Depth of injury for all five dermal elements was related to temperature and exposure times (ANOVA, p < 0.001 for each). The depth of injury in the paired sets of burns was highly consistent (Pearson correlation, range = 0.88-0.95). Inter- and intraobserver correlations were excellent for all measured elements (range = 0.91-0.97 and 0.95-0.99, respectively)., Conclusions: The authors describe a simple and reproducible animal burn model and histopathologic scale for measuring burn depth that they believe will facilitate standardization and comparison within future burn studies.

Objective: To compare re-epithelialization rates of superficial partial-thickness burns treated with octylcyanoacrylate (OCA), silver sulfadiazine (SSD), and dry gauze (controls) in swine., Methods: This was a prospective, longitudinal, blinded, controlled, experimental trial using anesthetized swine. Sixty-three standardized burns were created by applying an aluminum bar preheated to 80 degrees C for 20 seconds to the flanks of four young pigs. Three equal sets of 21 burns were randomly treated with OCA spray, SSD, or dry gauze (controls). Full-thickness biopsies were taken after 30 minutes and at seven and 14 days for blinded histopathologic evaluation by two dermatopathologists using hematoxylin and eosin staining. The percent of wound re-epithelialization was measured at days 7 and 14, calculated by dividing the length of the regenerated epidermis by the measured width of the biopsy. Analysis of variance (ANOVA) and repeated-measures ANOVA controlling for the individual pig were used for comparisons among groups. This study had 80% power to demonstrate a large between-group difference in percent re-epithelization (alpha = 0.05)., Results: There were 63 burns and 126 biopsies. Ten biopsies were excluded for technical reasons. At seven days, there was a significant between-group difference in percent re-epithelialization. Percent re-epithelialization was greatest in the OCA group (65.0%), followed by the SSD group (37.6%), and lowest in the control group (8.8%). At 14 days, all wounds demonstrated near complete re-epithelialization and there was no significant difference in the percent of re-epithelialization among the groups. There was only one wound infection in the OCA group., Conclusions: Under these study conditions, treatment of partial-thickness burns with OCA spray resulted in a higher percent of re-epithelialization at seven but not 14 days when compared with both SSD and control, with no significant increase in infection rates. Future studies should evaluate the use of OCA for the treatment of burns in humans.

Objective: Low-frequency sonophoresis has recently been shown to significantly facilitate transdermal permeability of various substances (e.g., insulin) in animal models, thus eliminating the need to inject such agents. Prior to human trials, the authors studied the safety profile of low-frequency sonophoresis in dogs by evaluating microscopic and temperature changes in the skin after sonophoresis., Methods: An evaluator-blinded canine study of sonophoresis using different energy intensities and probe diameters was performed. Low-frequency ultrasound was applied for 60 seconds to the clipped abdominal skin of 3 anesthetized adult mongrel dogs using a sonicator operating at a frequency of 20 KHz with a maximal energy output of 400 W. The sonicator was immersed in normal saline, and intensities of 4%, 10%, 20%, 30%, and 50% were applied during 600 msec of every second (pulsed mode). Three probes, 1-cm cylindrical, 5-cm cylindrical, and 10-cm disc-shaped, were evaluated. Each experimental condition was performed twice. Subcutaneous temperatures were measured by temperature probe before and after sonophoresis. At 30 minutes post-sonophoresis, full-thickness skin biopsies were taken for blinded histopathologic evaluation., Results: Minimal urticarial reactions were noted with the 1-cm probe at intensities of < or = 20% and with the 5-cm probe at 4% intensity. With higher intensity, thermal injuries were observed grossly with erythema and vesicles. The microscopic correlates were papillary and dermal edema with neutrophils and telangiectasia. The conditions producing vesicles grossly had foci of epidermal necrosis, subepidermal vesicles, and degeneration of papillary dermal collagen. With still higher intensities, confluent epidermal necrosis became apparent. Use of the 10-cm probe did not result in any injury., Conclusions: Low-frequency ultrasound at low intensities appears safe for use to enhance the topical delivery of medications, producing only minimal urticarial reactions. Higher-intensity conditions resulted in second-degree burns, most likely attributable to localized heating.