Julie A. Rizzo

Moderate systemic hypothermia decreases burn depth progression.

BACKGROUND Therapeutic hypothermia has been proposed to be beneficial in an array of human pathologies including cardiac arrest, stroke, traumatic brain and spinal cord injury, and hemorrhagic shock. Burn depth progression is multifactorial but inflammation plays a large role. Because hypothermia is known to reduce inflammation, we hypothesized that moderate hypothermia will decrease burn depth progression. METHODS We used a second-degree 15% total body surface area thermal injury model in rats. Burn depth was assessed by histology of biopsy sections. Moderate hypothermia in the range of 31-33°C was applied for 4h immediately after burn and in a delayed fashion, starting 2h after burn. In order to gain insight into the beneficial effects of hypothermia, we analyzed global gene expression in the burned skin. RESULTS Immediate hypothermia decreased burn depth progression at 6h post injury, and this protective effect was sustained for at least 24h. Burn depth was 18% lower in rats subjected to immediate hypothermia compared to control rats at both 6 and 24h post injury. Rats in the delayed hypothermia group did not show any significant decrease in burn depth at 6h, but had 23% lower burn depth than controls at 24h. Increased expression of several skin-protective genes such as CCL4, CCL6 and CXCL13 and decreased expression of tissue remodeling genes such as matrix metalloprotease-9 were discovered in the skin biopsy samples of rats subjected to immediate hypothermia. CONCLUSIONS Systemic hypothermia decreases burn depth progression in a rodent model and up-regulation of skin-protective genes and down-regulation of detrimental tissue remodeling genes by hypothermia may contribute to its beneficial effects.

Perioperative Temperature Management During Burn Care.

Major physiologic alterations following a severe thermal injury disrupt thermal homeostasis and predispose burn patients to hypothermia. An important recommendation in many clinical practice guidelines is to increase the ambient temperature during the care of severely burned patients in the operating room and intensive care unit to mitigate the loss of thermoregulation, prevent hypothermia, and minimize the impact of hypermetabolism. However, the scientific support for this recommendation remains unclear. This review summarizes the current knowledge regarding the pathophysiology and treatment of thermal injury–induced hypermetabolism and hypothermia, with special emphasis on alterations in ambient temperature. Current evidence on the value of increasing ambient temperature during the care of severely burned patients in the operating room or intensive care unit is limited, with minimal human studies investigating physiologic benefit or potential adverse effects.

Impact of isolated burns on major organs: a large animal model characterized

ABSTRACT Severe burn results in systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction (MOD). Currently, large-animal models of burn-induced SIRS/MOD mostly use secondary insults resulting in a paucity of knowledge on the effect of burn alone on different organ systems. The objective of the current study was to develop and characterize a large animal model of burn-induced SIRS over the course of 2 weeks. Yorkshire swine (n = 16) were randomized to sham controls (n = 4) or 40% total body surface area contact burns (n = 6 at 2 and 14 days post-burn). Blood chemistry and complete blood count analyses were performed at baseline and post-burn days 1, 2, 3, 7, 10, and 14. Upon euthanasia, tissue samples were taken for histopathology. Burns were found to be full thickness and did not re-epithelialize. SIRS was evidenced by increased body temperature, respiration rate, pulse, and white blood cell count for the duration of the experiment. Both acute liver injury and acute kidney injury were induced as determined biochemically and histologically. Histology also revealed atelectasis of the lungs which was associated with increased myeloperoxidase activity. Intestinal structure as well as enterocyte homeostasis was also disrupted. All of these organ abnormalities recovered to varying degrees by 14 days post-burn. We report a unique reproducible large animal model of burn-induced SIRS that can be tailored to specific organ systems for investigation into potential immunomodulatory interventions that prevent organ failure or promote organ recovery after burn injury.

Vitamin C in Burn Resuscitation.

The inflammatory state after burn injury is characterized by an increase in capillary permeability that results in protein and fluid leakage into the interstitial space, increasing resuscitative requirements. Although the mechanisms underlying increased capillary permeability are complex, damage from reactive oxygen species plays a major role and has been successfully attenuated with antioxidant therapy in several disease processes. However, the utility of antioxidants in burn treatment remains unclear. Vitamin C is a promising antioxidant candidate that has been examined in burn resuscitation studies and shows efficacy in reducing the fluid requirements in the acute phase after burn injury.

Burn Casualty Care in the Deployed Setting

Management of wartime burn casualties can be very challenging. Burns frequently occur in the setting of other blunt and penetrating injuries. This clinical practice guideline provides a manual for burn injury assessment, resuscitation, wound care, and specific scenarios including chemical and electrical injuries in the deployed or austere setting. The clinical practice guideline also reviews considerations for the definitive care of local national patients, including pediatric patients, who are unable to be evacuated from theater. Medical providers are encouraged to contact the US Army Institute of Surgical Research (USAISR) Burn Center when caring for a burn casualty in the deployed setting.

The Use of a Silver–Nylon Dressing During Evacuation of Military Burn Casualties

The military has used silver-nylon dressings as a topical antimicrobial on combat-related burns for the past 15 years. However, their clinical efficacy and associated risks have not been evaluated. Herein, the authors document our experience with the use of a specific silver-nylon dressing (Silverlon®) during global evacuation of casualties from combat zones to the United States sArmy Institute of Surgical Research Burn Center. A 10-year retrospective analysis was performed. Variables included patient demographics, total body surface area, length of stay, Injury Severity Score, incidence of urinary tract and burn infections, pneumonia, patient status at the time of discharge, and a composite endpoint. The patient cohort was stratified into two groups: Silverlon® (Group 1) and topical antimicrobial agents (Group 2). Data were analyzed using appropriate statistical tests (P ≤ .05). Nine hundred eighty-eight patients (26 ± 6 years) were identified with 184 patients (Group 1) and 804 patients (Group 2). Silver-nylon dressings trended toward decreased wound infection rate (5.4 vs 9.5%) even when applied to full-thickness burn injuries. When compared with topical antimicrobial agents, the silver-nylon dressing was not associated with significant differences in burn-related complication. The authors demonstrate the antimicrobial efficacy of the silver-nylon dressing during global evacuation of burn casualties from combat zones to the burn center. Compared with topical antimicrobials, the silver-nylon dressing is lightweight and easy to apply and requires minimal wound management which makes it desirable as a burn dressing for combat applications as well as mass casualty situations.

Predicting the Ability of Wounds to Heal Given Any Burn Size and Fluid Volume: An Analytical Approach

The intrinsic relationship between fluid volume and open wound size (%) has not been previously examined. Therefore, we conducted this study to investigate whether open wound size can be predicted from fluid volume plus other significant factors over time and to evaluate how machine learning may perform in predicting open wound size. This retrospective study involved patients with at least 20% TBSA burned. Various predictive models were developed and compared using goodness-of-fit statistics (R2, error [mean absolute error (MAE), root mean squared error (RMSE)]). Bland-Altman analysis was also performed to determine bias. A total of 121 patients were included in the analysis. Median TBSA burned was 31% (interquartile range: 26-46%). Average crystalloid volumes were 4.0 ± 2.7 ml/kg/TBSA in the first 24 hours. There were 24 (20%) patients who died. Importantly, multivariate analysis identified seven independent predictors of open wound size. Also, machine learning analysis was able to stratify patients based on the 20th day after admission, ~40% TBSA burned, and fluid volumes. Models for predicting open wound size varied in performance (R2 = .79-.90, MAE = 3.97-7.52, RMSE = 7.11-10.69). Notably, a combined machine learning model using only four features (fluid volume, days since admission, TBSA burned, age) performed the best and was sufficient to predict open wound size, with >90% goodness of fit and <4% absolute error. Bland-Altman analysis showed that there were no biases in the models. Open wound size can be predicted reliably using machine learning and fluid volume, days since admission, TBSA burned, and age. Future work will be needed to validate the utility of this studys models in a clinical environment.

Strength and Cardiorespiratory Exercise Rehabilitation for Severely Burned Patients During Intensive Care Units: A Survey of Practice

Minimizing the deconditioning of burn injury through early rehabilitation programs (RP) in the intensive care unit (ICU) is of importance for improving the recovery time. The aim of this study was to assess current standard of care (SOC) for early ICU exercise programs in major burn centers. We designed a survey investigating exercise RP on the ICU for burn patients with >30% total burned surface area. The survey was composed of 23 questions and submitted electronically via SurveyMonkey® to six major (pediatric and adult) burn centers in Texas and California. All centers responded and reported exercise as part of their RP on the ICU. The characteristics of exercises implemented were not uniform. All centers reported to perform resistive and aerobic exercises but only 83% reported isotonic and isometric exercises. Determination of intensity of exercise varied with 50% of centers using patient tolerance and 17% using vital signs. Frequency of isotonic, isometric, aerobic, and resistive exercise was reported as daily by 80%, 80%, 83%, and 50% of centers, respectively. Duration for all types of exercises was extremely variable. Mobilization was used as a form of exercise by 100% of burn centers. Our results demonstrate that although early RP seem to be integral during burn survivors ICU stay, no SOC exists. Moreover, early RP are inconsistently administered and large variations exist in frequency, intensity, duration, and type of exercise. Thus, future prospective studies investigating the various components of exercise interventions are needed to establish a SOC and determine how and if early exercise benefits the burn survivor.

A Survey of Temperature Management Practices Among Burn Centers in North America

Maintaining body temperature is a unique challenge with burn care. We sought to describe core temperature goals in the operating room (OR) and the methods used to achieve and maintain these goals, along with current methods of warming in the intensive care unit (ICU), the perception of effect of increased ambient temperature on work performance, and concerns with contamination of sterile fields due to increased ambient temperature. A 24 question survey was disseminated to burn centers in the United States and Canada. The questions included demographics, target core and ambient temperatures, warming methods, and beliefs on ambient temperatures effects. Of 121 burn centers, 52 questionnaires were completed (43% response rate). The majority of centers targeted a core temperature between 36 and 38°C in the OR and an ambient temperature between 75 and 95°F in the ICU. The most common methods for maintaining core temperature included warmed ambient temperature, forced air devices, and intravenous fluids. Although the majority of centers reported the belief that increased ambient temperature benefits patients, many also reported that there is a negative impact on staff performance and risk of staff perspiration contaminating sterile fields. Burn centers reported a range of target core temperatures and methods to reach target temperatures. More than a third of respondents perceived a negative impact work performance while more than half acknowledged the potential for contamination of sterile fields. A prospective observational study is needed to determine actual temperature regulation practice patterns and its impact on outcomes.

Renal Replacement Therapy in Severe Burns: A Multicenter Observational Study

Abstract Acute kidney injury (AKI) after severe burns is historically associated with a high mortality. Over the past two decades, various modes of renal replacement therapy (RRT) have been used in this population. The purpose of this multicenter study was to evaluate demographic, treatment, and outcomes data among severe burn patients treated with RRT collectively at various burn centers around the United States. After institutional review board approval, a multicenter observational study was conducted. All adult patients aged 18 or older, admitted with severe burns who were placed on RRT for acute indications but not randomized into a concurrently enrolling interventional trial, were included. Across eight participating burn centers, 171 subjects were enrolled during a 4-year period. Complete data were available in 170 subjects with a mean age of 51 ± 17, percent total body surface area burn of 38 ± 26% and injury severity score of 27 ± 21. Eighty percent of subjects were male and 34% were diagnosed with smoke inhalation injury. The preferred mode of therapy was continuous venovenous hemofiltration at a mean delivered dose of 37 ± 19 (ml/kg/hour) and a treatment duration of 13 ± 24 days. Overall, in hospital, mortality was 50%. Among survivors, 21% required RRT on discharge from the hospital while 9% continued to require RRT 6 months after discharge. This is the first multicenter cohort of burn patients who underwent RRT reported to date. Overall mortality is comparable to other critically ill populations who undergo RRT. Most patients who survive to discharge eventually recover renal function.