Annals of Burns and Fire Disasters - vol. IX - n. 1 - March 1996

USE OF AN ACELLULAR ALLOGRAFT DERMAL MATRIX (ALLODERM) IN THE MANAGEMENT OF FULLTHICKNESS BURNS

This report describes the early clinical and histological observations of a processed acellular dermal matrix (AlloDerm) grafted simultaneously with an overlying split-thickness skin graft in two patients with full-thickness burn injury. This acellular dermal matrix was produced from fresh human cadaver skin by a carefully controlled process that removed the epidermis and the cells from the dermis without altering the extracellular matrix structure and the basement membrane complex. Alloderm showed a high percentage of take and supported the overlOng split-thickness skin autograft. The clinical observation of take was confirmed histologically and by electron microscope. No specific immune response was detected. It was found that the supplemental dermis supplied by AlloDerm potentially improved the healing characteristics of a meshed autograft, with the clinically important implication of the possible closure of an extensively burned patient using minimal autograft skin. The skin cover thus provided is of superior quality to that normally obtained with widely meshed, thin autografts, which have a tendency to scarring and contracture.

CYTOTOXICITY OF WOUND DRESSING MATERIALS ASSESSED USING CULTURED SKIN EQUIVALENTS

The reason for this study was the need to identify the most suitable dressing for skin equivalents once they have been grafted on to patients. The dressing industry presents a vast array of wound coverings, ranging from simple paraffin gauze to complex dressings designed to act as skin substitutes. An in vitro system, based on the Bell model of cultured composite skin equivalents, was therefore devised to assess the effect of a number of wound dressings on DNA synthesis. DNA synthesis was quantified by immunocytohistochemical identification of incorporated bromodeoxyuridine and the percentage of labelled cells was measured after 7 days' exposure to the dressing material. Variations in the labelling index were observed from replica gels covered by different dressing materials and between dressings of the same type of material but produced by different manufacturers. In all, 26 types of dressing material were considered, including Comfeel, Duoderm E, Jelonet, Omiderm, Opsite Sheet and Silastic foam, to name just a few.

THE ASSOCIATION OF CIRCULATING ENDOTOXAEMIA WITH THE DEVELOPMENT OF MULTIPLE ORGAN FAILURE IN BURNED PATIENTS

Little is known of the importance of endotoxaerni a in the pathogenesis of the post-burn septic syndrome, which may lead to multiple organ failure (MOF). The correlation between plasma endotoxin levels and the progression of MOF remains controversial. Considering the important diagnostic and therapeutic advantages of resolving this controversy, a method was developed to measure plasma endotoxin concentration. This employed the modified endotoxin-specific limulus test (Endospecy test) and pretreatment of plasma samples by a new perchloric acid method. A prospective cohort study was conducted in 17 patients admitted with bums in over 70% TBSA. Seven of the patients developed MOR A significantly higher incidence of positive endotoxin tests (~!0.120 EU/ml) was found in patients who developed MOF than in patients who did not develop it (P <(f.05). An increase in mean endotoxin levels corresponded to an increase in the incidence of MOF and the death rate. Persistent endotoxaemia had a poor prognosis. It can be concluded that systemic endotoxaemia is an important factor for the high morbidity and mortality of sepsis and MOF following large bums. Sequential analyses of circulating endotoxin levels may thus be useful to predict the possible development of MOF and prognosis of clinical outcome.

Yao Y.M., Sheng Z.Y. (Sheng C.Y.), Tian H.M., Yu Y., Wang Y.P.,
Yang H.M., Guo Z.R., Gao W.Y.
Burns, 21: 255-8, 1995.

USE OF PREPUTIAL SKIN FOR THE RELEASE OF BURN CONTRACTURES IN CHILDREN

The stretched-out prepuce can provide a surprisingly large amount of full-thickness skin - even up to 25 cin' can be obtained from a 3-year-old boy. This can prove useful in the case of post-burn contractures requiring release procedures. The results are described of the use of preputial skin obtained from circumcision in 10 male Chinese children in whom release procedures were necessary (three for contractures around the knee, three on the dorsum of the foot, two at the elbow, and two at the wrist). The technique yielded reliable results and_ was well accepted by the children's parents. The major disadvantage of the technique is the increase in pigmentation of the prepuce as the child grows.

DERMATOGRAPHY: A METHOD FOR PERMANENT REPIGMENTATION OF ACHROMIC BURN SCARS

Dertnatography is a refined tattooing technique which was used successfully in 52 patients suffering from post-burn pigmentation. The first author has developed a special derma injector, the van der Velden dermainjector, which is a standard tattooing machine with certain modifications to the normal technical specifications. The cosmetic results of the use of this instrument proved to be satisfactory in a 5-year follow-up period. The method is perfectly safe. Dermatography is recommended as an alternative technique for treating localized achromasia, especially in cases where other medical therapeutic attempts have not succeeded in repigmenting the scars.

INCREASED PHYSIOLOGICAL DEAD SPACEITIDAL VOLUME RATIO DURING EXERCISE IN BURNED CHILDREN

This investigation was designed as part of a longitudinal assessment to evaluate the exercise gas exchange process in children convalescing from thermal injury. Exercise testing makes it possible to evaluate simultaneously the ability of the vascular and the respiratory systems to perform gas exchange. Spirometry, lung volume and exercise stress testing were monitored in 40 children with a mean postburn time of 2.6 ± 1.9 years and a mean burn size of 44 ± 22 per cent TBSA. The respiratory variables considered during exercise included expired volume, tidal volume and respiratory rate, and physiological dead space/tidal volume (VD/VT) ratios. Stress testing showed an increase in the VD/VT ratio consistent with uneven ventilation/perfusion relationships. The findings suggest that patients who survive thermal injury may not regain normal cardiopulmonary homeostasis. This is the first study of the exercise gas exchange process in burned children.

This article considers the causes of pain in burn patients and its treatment. The pain-generating mechanisms are nociception, hyperalgesia and neuropathy. The clinical picture of burn pain is described, with reference to its components and intensity, continuous pain due to the injuries, pain due to therapeutic procedures, pain after healing, and the time-course of pain. The treatment of burn pain involves a number of problems: fear of opioid side-effects, fear of opioid addiction, lack of pain evaluation, and lack of pain treatment protocol. The basic principles of pharmacological treatment are indicated, with recommendations for pharmacotherapy for pain at rest and for pain due to therapeutic procedures. Non-pharmacological treatment and pain in burned children are also considered. The necessity of accurate pain evaluation is underlined.

A STUDY OF CYTOKINES IN BURN BLISTER FLUID RELATED TO WOUND HEALING

It was found in this study that retention fluid from blisters of partial skin thickness burns, which contains relatively large amounts of cytokines and growth factors, stimulates wound healing. Approximately 2-3 mI of exudate retained in blisters of partial skin thickness burns were collected from 12 burn patients within 48 hours of their injury and snap frozen. Epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) levels were found to be low, while there were relatively large amounts of cytokines including platelet derived growth factor (PDGF), interleukin (IL-6) and transforming growth factor (TGF) a, which stimulated wound healing. TGF B, which is important in collagen metabolism and scar formation, was also found. It was discovered, contrary to expectation, that IL-1 oc and B, which both trigger inflammation, were present at relatively low levels, while IL-8 levels were rather high. Various cytokines co-existed in a balanced state in the burn blister fluid, suggesting that epithelialization may be regulated via a cytokine network operating on the wound surface. When 1% or more of blister fluid was added to the medium there was a significant increase in the growth of keratinocytes in culture.

EFFECT OF GLYCEROL ON INTRACELLULAR VIRUS SURVIVAL: IMPLICATIONS FOR THE CLINICAL USE OF GLYCEROL-PRESERVED CADAVER SKIN

Although glycerol has long been used for the preservation of skin allografts, its antimicrobial activity has not been fully documented. This study presents the results of an investigation of a model that considers the effect of glycerol on the inactivation of intracellular viruses. Two viruses were used in the study: herpes simplex type I (HSV-1) and poliovirus. These were cultured in human dermal fibroblasts. The intracellular viruses were incubated with 50%, 85% and 98% glycerol at 4 'C and 20 'C for 4 weeks. The cultures in glycerol and controls in fibroblast maintenance medium were assayed each week for virus infectivity by examining the ability of harvested viruses to infect further fibroblasts. The results showed that glycerol can reduce intracellular virus infectivity. However, its effects are closely dependent on concentration, time and temperature, and it is recommended that before clinical use allograft skin should be exposed to 98% glycerol for a minimum of at least 4 weeks at a minimum temperature of 20 'C

The first mesh skin graft was performed in Atlanta, Georgia in 1963. This article considers the evolution of the instrumentation used since then and the basic principles involved in the technique. Meshing instruments can be classified in four types: historical and other instruments; flat models; roller devices with cutting blades at one side; and roller devices with cutting rollers at both sides. A number of commercially available devices are considered and compared. It was found there was an overall difference between the expansion claimed by the manufacturers of the devices and the expansion as mathematically calculated. This study proposes a general formula which allows an objective comparison of expansion ratios of skin meshers, available now and in the future. Optimal usage of the parameters involved, especially the width of the ribbons of the meshgraft, allows shorter length of cuts and leads to shorter healing times.

Vandeput L, Nelissen M., Tanner LC., Boswick J.
Burns, 21: 364-70, 1995.