The effect of obesity on adverse outcomes and metabolism in pediatric burn patients.

HYPOTHESIS: Obesity influences metabolism and increases the incidence of clinical complications and worsens outcomes in pediatric burn patients. DESIGN: Retrospective, single-center study. SUBJECTS: In all, 592 severely burned pediatric patients who had burns covering more than 30% of the total body surface area and who were treated between 2001 and 2008 were enrolled in this study. Patients were divided into ≥85th percentile (n=277) and normal (n=315) weight groups based on body mass index (BMI) percentiles. RESULTS: Patients stratified below (normal) and ≥85th percentile had similar age, gender distribution and total burn size. No significant differences were detected in the incidence of sepsis (11% for obese vs 10% for normal), the incidence of multiple organ failure (MOF) (21% for obese and 16% for normal) or mortality (11% for obese vs 8% for normal). Compared with the normal group, the ≥85th percentile group had low levels of constitutive proteins (α2macroglobulin and Apolipoprotein A1) (P<0.05 for both) as well as high levels of triglycerides and the acute-phase protein, C-reactive protein (P<0.05 for both) up to 60 days after injury. Patients ≥85th percentile showed a significant higher loss of bone mineral density and lipolysis compared with normal individuals. Stepwise logistic regression analysis revealed that BMI had a positive predictive value towards the maximum DENVER2 score, an index of organ failure (P<0.001). CONCLUSIONS: BMI≥85th percentile altered the post-burn acute phase and catabolic response but did not increase the incidence of sepsis, MOF or mortality in pediatric burn patients. Our results suggest that impaired metabolism and an altered inflammatory response already exists in patients starting at the 85th percentile BMI.

Pre-clinical evaluation of liposomal gene transfer to improve dermal and epidermal regeneration.

Liposomal gene transfer effectively enhances dermal and epidermal regeneration in burned rodents. To advance this treatment to clinical studies, we investigated the efficacy of liposomal gene transfer in a clinically relevant porcine wound model. Mimicking the clinical scenario, six female Yorkshire pigs (40-50 kg) received up to 12 burns of 50 cm(2) area that were fully excised and covered with skin autograft meshed at 4:1 ratio 24 h post-burn. Animals received control injections (empty liposomes), liposomes (DMRIE-C) containing 1 mg LacZ-cDNA, or liposomes (DMRIE-C) with 1 mg of platelet-derived growth factor (PDGF)-cDNA, or the naked PDGF gene. Serial biopsies were taken from different wound sites at multiple time points up to 12 days post-wounding. Transfection efficacy and transfection rate of LacZ and localization of beta-gal were determined by immunohistochemical and immunofluorescent techniques. RT-PCR and multiplex protein analysis (ELISA) were used to measure levels of growth factor mRNA transcribed and growth factor protein translated. Wound re-epithelialization and graft adhesion was evaluated using planimetric analysis and clinical scores. We found that peak transfection of liposomal beta-galactosidase occurred on day 2, with a fluorescence increase of 154% to baseline (P<0.001). Transfection intensity dropped to 115% above baseline on day 4 (P<0.001) and 109% on day 7. Immunohistochemistry showed a maximum transfection rate of 34% of cells in wound tissue. Gene transfer of liposomal PDGF-cDNA resulted in increased PDGF-mRNA and protein expression on days 2 and 4, and accelerated wound re-epithlialization as well as graft adhesion on day 9 (P<0.05). In this study, we showed that liposomal cDNA gene transfer is possible in a porcine wound model, and by using PDGF-cDNA we further showed that dermal and epidermal regeneration can be improved. These data indicate that liposomal gene transfer can be a new therapeutic approach to improve wound healing in humans.

[Pathophysiology of acute lung injury in severe burn and smoke inhalation injury]. / Pathophysiologie des akuten Lungenversagens bei Schwerbrandverletzten mit Inhalationstrauma.

This review article describes the pathophysiological aspects of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), induced by combined burn and smoke inhalation and examines various therapeutic approaches. The injury results in a fall in arterial oxygenation as a result of airway obstruction, increased pulmonary transvascular fluid flux and loss of hypoxic pulmonary vasoconstriction. The changes in cardiopulmonary function are mediated by reactive oxygen and nitrogen species. Nitric oxide (NO) is generated by both inducible and constitutive isoforms of nitric oxide synthase (NOS). Recently, neuronal NOS emerged as a major component within the pathogenesis of ARDS. NO rapidly combines with the oxygen radical superoxide to form reactive and highly toxic nitrogen species such as peroxynitrite. The control of NO formation involves poly(ADP-ribose) polymerase and its ability to up-regulate the activity of nuclear transcription factors through ribosylation. In addition, present data support a major role of the bronchial circulation in the injury, as blockage of bronchial blood flow will also minimize the pulmonary injury. Current data suggest that cytotoxins and activated cells are formed in the airway and carried to the parenchyma.

The combination of IGF-I and KGF cDNA improves dermal and epidermal regeneration by increased VEGF expression and neovascularization.

Insulin-like growth factor-I (IGF-I) and keratinocyte growth factor (KGF) cDNA gene transfer individually improves dermal and epidermal regeneration. The aim of the present study was to determine whether the combination of IGF-I plus KGF cDNA further improves wound healing and by which mechanisms these changes occur. Rats received an acute wound and were divided into four groups to receive weekly subcutaneous injections of liposomes plus Lac Z cDNA, liposomes plus IGF-I cDNA, liposomes plus KGF cDNA, or liposomes plus IGF-I/KGF cDNA. Planimetry, immunological assays, histological and immunohistochemical techniques were used to determine IGF-I, KGF, platelet-derived growth factor, fibroblast growth factor (FGF), transforming growth factor-beta and vascular endothelial growth factor (VEGF) expression and different types of collagen (I, III and IV). IGF-I, KGF and their combination cDNA treatment significantly (P<0.05) accelerated re-epithelization, increased IGF-I, KGF, FGF, VEGF and collagen type IV expression, while it had no effect on collagen type I and III expression. The combination of IGF-I plus KGF cDNA increased (P<0.05) neovascularization and VEGF expression when compared to IGF-I cDNA, KGF cDNA groups and controls. In conclusion, exogenous administration of liposomal IGF-I plus KGF cDNA enhanced dermal and epidermal regeneration which is due to increased neovascularization.

Beta-blockade in burns.

A significant proportion of the mortality and morbidity of severe burns is attributable to the ensuing hypermetabolic response that typically lasts for at least 9-12 months post-injury. This is associated with impaired wound healing, increased infection risks, erosion of lean body mass, hampered rehabilitation and delayed reintegration of burn survivors into society. The endocrine status is markedly altered during this period with an initial and then sustained increase in proinflammatory 'stress' hormones such as cortisol and other glucocorticoids, and catecholamines including epinephrine and norepinephrine by the adrenal medulla and cortex. These hormones exert catabolic effects leading to muscle wasting, the intensity of which depends upon the percentage of total body surface area (TBSA) involved, as well as the time elapsed since initial injury. Pharmacological and non-pharmacological strategies may be used to reverse the catabolic effect of thermal injury. Of these, beta-adrenergic blockade with propranolol has been the most efficacious anti-catabolic therapy in the treatment of burns. The underlying mechanism of action of propranolol is still unclear, however its effect appears to occur due to an increased protein synthesis in the face of a persistent protein breakdown and reduced peripheral lipolysis. This article aims to review the current understanding of catecholamines in postburn muscle wasting and focuses on the clinical and metabolic effects of beta-blockade in severe burns.

Gene therapy in wound healing: present status and future directions.

Gene therapy was traditionally considered a treatment modality for patients with congenital defects of key metabolic functions or late-stage malignancies. The realization that gene therapy applications were much vaster has opened up endless opportunities for therapeutic genetic manipulations, especially in the skin and external wounds. Cutaneous wound healing is a complicated, multistep process with numerous mediators that act in a network of activation and inhibition processes. Gene delivery in this environment poses a particular challenge. Numerous models of gene delivery have been developed, including naked DNA application, viral transfection, high-pressure injection, liposomal delivery, and more. Of the various methods for gene transfer, cationic cholesterol-containing liposomal constructs are emerging as a method with great potential for non-viral gene transfer in the wound. This article aims to review the research on gene therapy in wound healing and possible future directions in this exciting field.

Ghrelin improves burn-induced delayed gastrointestinal transit in rats.

Delayed gastrointestinal transit is common in patients with severe burn. Ghrelin is a potent prokinetic peptide. We aimed at testing the effect of ghrelin on burn-induced delayed gastrointestinal transit in rats. Gastric emptying (GE), intestinal transit (IT), and colonic transit (CT) studies were performed in male Sprague-Dawley rats. Rats were randomized into two main groups as follows: sham injury and ghrelin-treated burn injury with doses of 0, 2, 5, and 10 nmol/rat ip 6 h after burn. Sham/burn injury was induced under anesthesia. Rats received a phenol red meal 20 min following ghrelin injection. Based on the most effective ghrelin dose, 1 mg/kg sc atropine was given 30 min before the ghrelin in one group of rats for each study. The rats in each group were killed 30-90 min later; their stomachs, intestines, and colons were harvested immediately, and the amount of phenol red recovered was measured. Percentage of gastric emptying (GE%) and geometric center for IT and CT were calculated. We found 1) severe cutaneous burn injury significantly delayed GE, IT, and CT compared with sham injury (P < 0.05); 2) ghrelin normalized both GE and IT, but not the CT; 3) the most effective dose of ghrelin was 2 nmol/rat; and 4) atropine blocked the prokinetic effects of ghrelin on GE% and IT. In conclusion, ghrelin normalizes burn-induced delayed GE and IT but has no effect on CT in rats. The prokinetic effects of ghrelin are exerted via the cholinergic pathway. Ghrelin may have a therapeutic potential for burn patients with delayed upper gastrointestinal transit.

[Treatment strategies for acute smoke inhalation injury]. / Behandlungsstrategien des akuten Rauchgasinhalationstraumas.

Most fatalities from fires are not due to burns, but are a result of inhalation of toxic gases produced during combustion. Fire produces a complex toxic environment, involving flame, heat, oxygen depletion, smoke and toxic gases such as carbon monoxide and cyanide. As a wide variety of synthetic materials is used in buildings, such as insulation, furniture, carpeting, electric wiring covering as well as decorative items, the potential for poisoning from inhalation of products of combustion is continuously increasing. The present review describes the pathophysiologic effects from smoke inhalation injury as well as strategies for emergency treatment on scene and in the intensive care setting.

Thermoregulation during exercise in severely burned children.

INTRODUCTION: Severe burns result in skeletal muscle catabolism and weakness, which is worsened by prolonged physical inactivity. Exercise would be an ideal tool in the rehabilitation of burned children. However, it has been postulated that burned children may have an excessive rise in body temperature during exercise compared to non-burned children, partly due to the reduced area available for heat dissipation, thereby questioning the safety of exercise in burned children. METHODS: Children (n = 15) with >40% total body surface area (TBSA) burns and non-burned children (n = 13) successfully completed this study. All subjects completed 20 minutes of treadmill exercise at approximately 75% of their peak aerobic power. Tympanic temperature (Ttym), burned and unburned skin temperature were recorded pre-exercise, every 2 minutes during exercise and during recovery. RESULTS: Within burned children, significant differences between the temperature of unburned skin and burned skin, during later stages of sub-maximal exercise (minutes 12-20) were present. However, there were no significant differences between burned and non-burned children in Ttym or unburned skin temperature indicating that severely burned children do not demonstrate an impaired thermoregulatory response to 20 minutes of sub-maximal exercise at room temperatures. CONCLUSION: It is concluded that exercise at moderate intensities conducted at room temperature is safe in burned children with <75% TBSA burns.

Lactate: early predictor of morbidity and mortality in patients with severe burns.

A severe burn results in a devastating and unique derangement called burn shock. Historically, resuscitation has been guided by a combination of basic laboratory values, invasive monitoring and clinical findings, but the optimal guide to the endpoint of resuscitation remains controversial. One-hundred sixty-six patients, who were admitted to our Burn Unit, were enrolled in this prospective study. Resuscitation of these patients was undertaken according to the current standard of care. Parkland formula was used as a first approximation of acquired fluid administration rates and fluid administration was adapted in order to meet clinical needs. The aim of this study was to evaluate if plasma lactate is a useful parameter to estimate the severity of a burn shock. One of the main objectives was to evaluate, if the lactate clearance adds additional information. The results of this study indicate that the initial lactate level (Day 0) is a useful parameter to separate survivors from non-survivors. Moreover, a significant marker of shock and resuscitation was observed in evaluating the lactate clearance on Day 1. A better chance of survival occurs when resuscitation results in a lactate clearance to normal values within 24h (survival was 68% if the lactate reached normal values, compared to 32% if the lactate level remained supra-normal). In summary, we believe that measuring lactate and lactate clearance may help to detect critically injured patients either for adequacy of treatment, or selection of other therapeutic options.

Immunological control of methicillin-resistant Staphylococcus aureus (MRSA) infection in an immunodeficient murine model of thermal injuries.

Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), is a major cause of sepsis in patients who are immunosuppressed by their burns. In this study, an immunological regulation of MRSA infection was attempted in a mouse model of thermal injury. SCIDbg mice were resistant to MRSA infection, while SCIDbgMN mice (SCIDbg mice depleted of neutrophils and macrophages (Mphi)) were susceptible to the same infection. Also, thermally injured SCIDbg mice were shown to be susceptible to MRSA infection. On the other hand, the resistance of SCIDbgMN mice to the infection was completely recovered after an inoculation with Mphi from normal mice. However, anti-MRSA resistance was not shown in SCIDbgMN mice inoculated with Mphi from thermally injured mice. Mphi from MRSA-infected thermally injured mice were identified as alternatively activated Mphi, and Mphi from MRSA-infected unburned mice were characterized as classically activated Mphi. Mphi from thermally injured SCIDbg mice previously treated with 2-carboxyethylgermanium sesquioxide (Ge-132) protected SCIDbgMN mice against MRSA infection. Ge-132 has been described as an inhibitor of alternatively activated Mphi generation. These results suggest that MRSA infection in thermally injured patients is controlled immunologically through the induction of anti-MRSA effector cells and elimination of burn-associated alternatively activated Mphi, which are cells that inhibit the generation of classically activated Mphi.

The structure and composition of liposomes can affect skin regeneration, morphology and growth factor expression in acute wounds.

Liposomal gene transfer is an effective therapeutic approach to improve dermal and epidermal regeneration. The purpose of the present study was to define whether the biological or chemical structure of a liposome influences cellular and biological regeneration in the skin, and to determine by which mechanisms possible changes occur. Rats were inflicted a full-excision acute wound and divided into three groups to receive weekly subcutaneous injections of DMRIE liposomes plus the Lac Z gene, or DOTAP/Chol liposomes plus the Lac Z gene, or saline. Planimetry, immunological assays, histological and immunohistochemical techniques were used to determine cellular responses after gene transfer, protein expression, dermal and epidermal regeneration. DOTAP/Chol increased IGF-I and KGF protein concentration and caused concomitant cellular responses, for example, by increasing IGFBP-3, P<0.05. DOTAP/Chol liposomes improved epidermal regeneration by exhibiting the most rapid area and linear wound re-epithelization compared to DMRIE or control, P<0.001. DOTAP/Chol and DMRIE exerted promitogenic and antiapoptotic effects on basal keratinocytes, P<0.05. Dermal regeneration was improved in DOTAP/Chol-treated animals by an increased collagen deposition and morphology, P<0.001. DOTAP/Chol liposomes increased vascular endothelial growth factor concentrations and thus neovascularization when compared with DMRIE and saline, P<0.001. In the present study, we showed that different liposomes have different effects on intracellular and biological responses based on its chemical and molecular structure. For gene transfer in acute wounds, the administration of DOTAP/Chol liposomes appears to be beneficial.

Effects of endotoxin on serum chemokines in man.

AIM: Endotoxin is known to be a primary initiator of sepsis and septic shock. Migration of immunocompetent cells due to chemotactic attraction plays a central role in the initiation of the immune response. Two major groups of chemokines can be distinguished: C-x-C chemokines like Interleukin-8 attract mainly neutrophils, C-C chemokines (e.g. RANTES) attract monocytes and T-cells. The aim of this study was to get further insight into chemokine profiles after a single endotoxin bolus in man. MATERIALS AND METHODS: We investigated the effect of systemically administered endotoxin (4ng/kg BW i.v.) in 8 healthy volunteers. Clinical data (heart rate, mean arterial pressure, temperature), serum levels of IL-8, and RANTES, as well as white blood cell count were obtained before and hourly for five hours after endotoxin administration. RESULTS: Heart rate and MAP showed significant changes (p<0.05) after 2-3 hours. All volunteers presented with low-grade fever after 2 hours. WBC was elevated 43% and 63% after 4 and 5 hours, respectively. Both chemokines were significantly different from baseline two hours after endotoxin challenge: While IL-8 was significantly increased RANTES serum levels were diminished. CONCLUSION: From our data we conclude that this endotoxin model was effective to mimic the clinical appearance of sepsis. Chemokines like IL-8 and RANTES are integrated in the early immune response to endotoxin challenge in man.

Retardation of wound healing by silver sulfadiazine is reversed by Aloe vera and nystatin.

Inhibition of wound contraction by topical anti microbial agents has been described. The purpose of this study was to further investigate that phenomenon and to explore the effect that other agents such as Aloe vera might have on this process. Full-thickness excised wounds were created on the dorsum of Sprague-Dawley rats under anaesthesia. The wounds were treated with topical agents three times daily for fourteen days, then observed until healed. Groups were: saline control, placebo (aqueous cream) control, silver sulphadiazine (SSD) cream 1%, SSD 0.5%, SSD 1% with Aloe vera, SSD 1% with nystatin, nystatin. Wound surface areas were measured each three days. Time to 50% and 90% healing was compared using ANOVA. Wound half-life and healing times were shortest in the SSD/Aloe vera and nystatin groups (P<0.05) and longest in the 1% SSD and saline control groups. The placebo group (aqueous cream) healed in a significantly shorter time (P<0.05) than the control (saline) group. Wound contraction was delayed by saline and SSD. Nystatin and Aloe vera, when added to SSD, reversed that effect. These data suggest that a dry wound (saline) heals slowly. Infection control without delay of wound healing is most appealing and clinical trials are planned.

Serial measurements increase the accuracy of laser Doppler assessment of burn wounds.

Traditional methods of judging burn depth by clinical evaluation of the wound based on appearance and sensation remain in wide use but are subject to individual variation by examiner. In addition to the clinical difficulties with burn wound management, observer dependency of wound assessment complicates clinical trials of burn wound therapy. A laser Doppler flowmeter with a multichannel probe was used to measure burn wound perfusion as a tool to predict wound outcome. Serial measurement with laser Doppler flowmetry had an 88% specificity and a positive predictive value of 81% for identifying nonhealing wounds. These results suggest that laser Doppler flowmetry is a potentially useful tool for burn wound assessment.

[Toxic epidermal necrolysis. A case for the burn intensive care unit]. / Toxisch epidermale Nekrolyse. Ein Fall für das Schwerverbranntenzentrum.

Toxic epidermal necrolysis is a rare but life-threatening exfoliating disease of the skin and mucous membranes, commonly considered a drug sensitivity reaction. In this review of the literature we discuss the epidemiology, etiology, and pathology. We show diagnostic problems and current treatment strategies. Many of the problems associated with the disease, such as wound infection, sepsis, nutritional support, and pain management, are similar to problems in severely burned patients. Burn centers provide optimal logistics and knowledge to diagnose and treat this serious disease entity.

Nutritional and pharmacological support of the metabolic response to injury.

Severe burn incites metabolic disturbances which last up to one year post injury. Persistent profound catabolism after severe burn hampers rehabilitative efforts delaying meaningful return of individuals to society. The simplest effective anabolic strategies for severe burn injuries are early excision and grafting of the burn wound, prompt treament of sepsis, maintenance of environmental temperature at 30-32 inverted exclamation mark C, continuous enteral feeding of a high carbohydrate, high protein diet, early institution of vigorous resistive and aerobic resistive exercise programs. To further minimize erosion of lean body mass administration of recombinant human growth hormone, insulin, oxandrolone or propranolol are all reasonable approaches. Exogenous continuous low dose insulin infusion, beta blockade with propranolol and the use of the synthetic testosterone analog, oxandrolone are the most cost effective and least toxic pharmaco therapies to date.

Skin toxicity induced by wet heat.

Pieces of human skin from the skin bank were heated in an autoclave for 1 or 5 min at temperatures 80, 90, 100, 110 and 135 degrees C. The pieces were then homogenized and the homogenates were injected intraperitoneally into groups of mice. The amount injected was either a quantity equivalent to 50 or 75% of the mouse body surface area. Fourteen separate experiments were carried out, each one with a variety of temperatures. Mortality in the groups of mice was recorded by the 8th day. Control mice received homogenates of skin heated to no more that 38 degrees C and out of a total of 104 control mice there were only 4 deaths. In contrast homogenates of skin heated to 135 degrees C killed from 80 to 100% of the mice in different groups, averaging 92%. Skin heated to 110 degrees C killed from 33 to 90% of the mice in different groups, averaging 63%. Skin heated to 100 degrees C killed from 0 to 80% of the mice in different groups, averaging 33%. Temperatures of 80 and 90 degrees C killed no more than 10% of the mice in any group, averaging less than 3%. One minute of heating seemed to be sufficient to induce the toxic effect in the skin. These findings indicated that wet heat application to skin was capable of inducing toxicity in a fashion similar to that demonstrated many years ago with hotter dry temperatures applied to skin for 15s. That application was shown to induce polymerization of skin cell membrane lipid proteins rendering them toxic. In this study, increasing toxicity appeared similarly to depend on the quantity of wet heat input as illustrated by the range of increasing temperatures. The relatively lower temperatures of scalding versus flame burns can accomplish similar dangerous effects; it is simply a quantitative matter of heat input.

The effect of prolonged euglycemic hyperinsulinemia on lean body mass after severe burn.

BACKGROUND: The hypermetabolic response to burn increases protein catabolism. Euglycemic hyperinsu-linemia with exogenous insulin maintains muscle protein by continued stimulation of net protein synthesis. Our aim was to determine the effect of euglycemic hyperinsulinemia over the entire hospitalization on muscle anabolism by investigating lean body mass (LBM) as the primary endpoint. METHODS: Eighteen subjects between the ages of 2 and 18 with burns of more than 40% were prospectively randomized into 2 groups, a control (n = 9) and a treatment group (n = 9). The treatment group was given continuous intravenous insulin at a rate of at least 1.5 microU/kg/min to maintain serum glucose levels between 100 to 140 mg/dL. Treatment was instituted 24 to 48 hours after arrival and continued until the patient's injury was 95% healed. All patients received continuous enteral feeding. Patients underwent body composition studies by dual-energy x-ray absorptiometry (DEXA) scan on postoperative day 6 after initial burn excision and when 95% healed. RESULTS: Nutritional intakes were not different between groups. In the control, subjects continued catabolism resulted in peripheral muscle wasting and centripetal obesity with diminished truncal LBM. The treatment group had improvement in lean body mass (P =.004) and bone mass (P =.025). The treatment group also had less peripheral muscle wasting with overall increases in upper/lower extremity LBM (P =.005). Hospital length of stay in days per percent of total body surface area burned was decreased in the insulin group (control = 1.03 +/- 0.1 vs 0.7 +/- 0.9 for insulin patients; P <.05). CONCLUSIONS: Euglycemic hyperinsulinemia throughout the hospital course mitigates muscle catabolism and preserves lean body mass.