Standardized burn model using a multiparametric histologic analysis of burn depth.

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.

[1]  Spencer Rj,et al.  Laser Doppler Flowmetry Evaluation of Burn Wound Depth , 1989 .

[2]  A. Singer.  Clinical wound evaluation scales. , 1998, Academic emergency medicine : official journal of the Society for Academic Emergency Medicine.

[3]  B. Hirshowitz,et al.  The influence of various microclimate conditions on the burn wound: a review. , 1982, Burns, including thermal injury.

[4]  R P Cole,et al.  Thermographic assessment of hand burns. , 1990, Burns : journal of the International Society for Burn Injuries.

[5]  J. Davies.  Physiological Responses to Burning Injury , 1982 .

[6]  M. Flint.  Interrelationships of mucopolysaccharide and collagen in connective tissue remodelling. , 1972, Journal of embryology and experimental morphology.

[7]  G. Leopold,et al.  B-mode ultrasonic echo determination of depth of thermal injury. , 1986, Burns, including thermal injury.

[8]  J. Callis,et al.  Multispectral imaging of burn wounds: a new clinical instrument for evaluating burn depth , 1988, IEEE Transactions on Biomedical Engineering.

[9]  B. Zawacki,et al.  AN EVALUATION OF PATENT BLUE V, BROMPHENOL BLUE, AND TETRACYCLINE FOR THE DIAGNOSIS OF BURN DEPTH , 1970, Plastic and reconstructive surgery.

[10]  Division on Earth.  Guide for the Care and Use of Laboratory Animals , 1996 .

[11]  G L Wolf,et al.  Assessing burn wound depth using in vitro nuclear magnetic resonance (NMR). , 1986, The Journal of surgical research.

[12]  R Schwarz,et al.  The Skin of Domestic Mammals as a Model for the Human Skin, with Special Reference to the Domestic Pig1 , 1978 .

[13]  T. Chvapil,et al.  Identification of the Depth of Burn Injury by Collagen Stainability , 1984, Plastic and reconstructive surgery.

[14]  L. Nanney,et al.  Progressive burn injury documented with vimentin immunostaining. , 1996, The Journal of burn care & rehabilitation.

[15]  D. Silverman,et al.  Evaluation of the burn wound with perfusion fluorometry. , 1982, The Journal of trauma.

[16]  A. Moritz,et al.  Studies of Thermal Injury: II. The Relative Importance of Time and Surface Temperature in the Causation of Cutaneous Burns. , 1947, The American journal of pathology.

[17]  D. Jackson.  A historical review of the use of local physical signs in burns. , 1970, British journal of plastic surgery.

[18]  R. Kreis,et al.  Histopathological evaluation of scalds and contact burns in the pig model. , 1994, Burns : journal of the International Society for Burn Injuries.

[19]  Douglas MacG. Jackson,et al.  The diagnosis of the depth of burning , 1953, The British journal of surgery.

[20]  E. Mcloughlin,et al.  Burn incidence and medical care use in the United States: estimates, trends, and data sources. , 1996, The Journal of burn care & rehabilitation.