Adjusting body weight for edema in severely burned patients.

Weight loss is difficult to quantify in critically ill burn patients, as the presence of edema can mask changes in dry body weight. We sought to estimate dry body weight using measured weights adjusted for reported extremity edema. We evaluated patients with at least 20% total body surface area (TBSA) burns admitted to our intensive care unit over a 3½-year period. Body weights were collected for this analysis from admission to the time of a recorded dry weight after wound healing. Extremity edema was collected at the time of each weight measurement and was categorized into three groups: (1) no edema, (2) 1 + pitting edema, (3) 2 + or 3 + pitting edema. Logistic regression yielded the following formula for estimating dry weight (in kg): 0.66 x measured body weight + 25 - (3 for 1 + pitting edema or 4 for 2 + or 3 + pitting edema of either upper extremity) - (4 for any pitting edema to either lower extremity) (p < 0.01, R2 = 0.81). These results may allow us to better estimate dry body weight changes in our edematous patients with severe burns. Nutrition goals can be adjusted earlier, when appropriate, based on these estimated dry body weight changes.

Evaluation of the use of sitagliptin for insulin resistance in burn patients.

BACKGROUND: Following severe burn injury, patients undergo profound metabolic changes, including insulin resistance and hyperglycemia. Hyperglycemia has been linked to impaired wound healing, increased risk of skin graft loss, increased muscle catabolism, increased infections, and mortality. Sitagliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor that improves glycemic control by slowing the inactivation of incretin hormones, increasing insulin synthesis and release from pancreatic beta cells and lowering glucagon secretion from pancreatic alpha cells. The objective of this study was to describe our institution's experience with using sitagliptin to help mitigate insulin resistance after burn injury. METHODS: This was a retrospective chart review that included 22 adult burn patients. Burn patients were prescribed sitagliptin regardless of their previous medical history of type 2 diabetes mellitus. Patients were included in this analysis if they were adults admitted for burn injury during a 13-month period and received at least 3 consecutive doses of sitagliptin. Patients were excluded if they did not have insulin use data 3 days pre- and 3 days post-sitagliptin initiation. The first day of sitagliptin initiation was considered day 0; data from day 0 were not included in either the pre- or post-sitagliptin analysis. RESULTS: In the 3 days prior to sitagliptin initiation, patients received a median of 114.3 units per day (IQR 49.1, 228) in an attempt to maintain a blood glucose goal of less than 180 mg/dL. In the 3 days after sitagliptin was started, exogenous insulin requirements significantly decreased to a median to 36.3 units per day (IQR 11.7, 95) (P=0.009). Seven patients were on insulin infusions at the time of sitagliptin initiation. After sitagliptin was started, it took a median of 3 days (IQR 2, 3.25) to be liberated from the insulin infusion. In terms of safety, there were two episodes of hypoglycemia (BG<70 mg/dL) after sitagliptin initiation, compared to three episodes prior to sitagliptin initiation (P=0.7). CONCLUSION: The addition of sitagliptin to burn patients' medication regimens significantly reduced insulin requirements over a 3-day period and allowed liberation from insulin drips.

Nutritional therapy among burn injured patients in the critical care setting: An international multicenter observational study on "best achievable" practices.

BACKGROUND & AIMS: Burn patients pose a number of clinical challenges for doctors and dietitians to achieve optimal nutrition practice. The objective of this study was to describe nutrition practices in burn center intensive care units (ICUs) compared to the most recent ESPEN and SCCM/ASPEN guidelines (hereafter referenced as "the Guidelines") and highlight the variation in practice and what is "best achievable." METHODS: In 2014-15, we prospectively enrolled 283 mechanically ventilated patients who were admitted to one of 14 burn ICUs for at least 72 h. Data collected included information on the estimation of energy and protein requirements, their actual delivery as well as route and time of feeding, and administration of micronutrients. We describe site practices and data per patient-day. RESULTS: Adherence to the Guidelines for the use of enteral nutrition (EN) over parenteral nutrition (PN) was 90.5% of patient-days (site range 79.2%-97.0%). However, adherence to the Guidelines for the measurement of energy requirements was 6.0% of patient-days (site range 0.0%-93.3%), supplementation with glutamine took place in 22.4% of patient-days (site range 0.0%-61.8%). Provision of 80% of energy requirements within 48-72 h was achieved in 35.3% of patients (site range 0.0%-80.0%), and provision of 80% of protein needs within 48-72 h was achieved in 34.3% of patients (site range 0.0%-80.0%). Average nutritional adequacy was 64.9 ± 40.0% for energy (best site: 80.2%, worst site: 42.0%) and 65.6 ± 42.1% for protein (best site: 87.3%, worst site: 43.6%). CONCLUSION: The present findings indicate that despite high adherence to providing EN over PN, there is still a large gap between many recommendations and clinical practice, and the achievement of nutrition goals for patients in burn centers is suboptimal.

High-Carbohydrate vs High-Fat Nutrition for Burn Patients.

Nutrition is an essential component of the healing and recovery process after severe burn injury. For many burn patients, nutrition support is necessary to meet nutrition goals. The ratio of carbohydrates and fat is particularly important for burn patients, as an essential fatty acid deficiency can contribute to poor wound healing. However, there is evidence to suggest that diets containing more carbohydrates and less fat may result in better patient outcomes. A literature search was conducted to identify studies related to nutrition support and macronutrient ratios in burn patients. Eleven published papers were found that considered macronutrient use in enteral and parenteral nutrition therapies among 9 different burn patient samples. No negative outcomes associated with lower fat, higher carbohydrate nutrition for severely burned patients were found in the literature. Conversely, the literature review revealed improved outcomes among severely burned patients receiving lower fat, higher carbohydrate nutrition to include fewer incidences of pneumonia, wound infections, acute respiratory distress syndrome, fatty liver, and sepsis. These patients also experienced shorter hospital length of stay and shorter wound healing times, as well as lower spleen and kidney weights, lower urinary nitrogen losses, improved nitrogen balance, higher insulin levels, higher insulin-like growth factor-1, lower cortisol, and less muscle protein breakdown. The evidence available to date supports the clinical use of nutrition support providing ≤15% fat and ≥60% carbohydrate for critically ill burn patients.

The Interplay of Nutrition, Physical Activity, Severity of Illness, and Mortality in Critically Ill Burn Patients: Is There a Connection?

The purpose of this project was to evaluate the relationships between nutrition, physical activity levels (PALs), severity of illness (SOI), and survival in critically ill burn patients. We conducted a retrospective evaluation of consecutively admitted adult patients who had an intensive care unit stay ≥8 days after ≥20% TBSA burns. Linear regression was used to assess the association between SOI (sequential organ failure assessment scores) and PALs as well as between SOI and nutritional intake. After univariate analysis comparing survivors and nonsurvivors, factors with P < .10 were analyzed with multiple logistic regression. Characteristics of the 45 included patients were: 42 ± 15 years old, 37 ± 17% TBSA burns, 22% mortality. Factors independently associated with survival were burn size (negatively) (P = .018), height (positively) (P = .006), highest PAL during the first eight intensive care unit days (positively) (P = .016), and kcal balance during the fifth through the eighth intensive care unit days (positively) (P = .012). Sequential organ failure assessment scores had a significant (P < .001) but weak association with nutrition intake (R2 = 0.05) and PALs (R2 = 0.25). Higher nutritional intake and activity were significantly associated with lower mortality in critically ill burn patients. Given the weak associations between both nutritional intake and PALs with SOI, the primary barrier in achieving nutrition and activity goals was not SOI. We recommend that physical rehabilitation and nutritional intake be optimized in an effort to improve outcomes in critically ill burn patients.

Predicting wound healing rates and survival with the use of automated serial evaluations of burn wounds.

Healing of burn wounds is necessary for survival; however tracking progression or healing of burns is an inexact science. Recently, the relationship of mortality and wound healing has been documented with a software termed WoundFlow. The objective of the current study was to confirm various factors that impact burn wound healing, as well as to establish a timeline and rate of successful healing. A retrospective analysis was performed on adults (n=115) with at least 20% TBSA burn that had at least two computer-based wound mappings. The % open wound (%OW) was calculated over time to document healing trajectory until successful healing or death. Only 2% of patients in the group with successful wound healing died. A decrease in the %OW of 0.8 (IQR: 0.7-1.1) was associated with survival. Disparities in wound healing trajectories between survivors and non-survivors were distinguishable by 2weeks post-injury (P<0.05). When %TBSA was stratified by decile, the 40-49% TBSA group had the highest healing rate. Taken together, the data indicate that wound healing trajectory (%OW) varies with injury severity and survival. As such, automated mapping of wound healing trajectory may provide valuable information concerning patient/prognosis, and may recommend early interventions to optimize wound healing.

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 temperature's 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.

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 study's models in a clinical environment.

Are visceral proteins valid markers for nutritional status in the burn intensive care unit?

The aim of this study was to determine whether visceral protein levels increase under positive nitrogen balance during times of decrease in acute-phase reactant levels in patients with burn injury. This was a post hoc analysis of a prospective, interventional study approved by the local institutional review board. A total of 10 subjects between the ages of 18 and 72 with ≥ 20% total body surface area burn were enrolled over a 14-month period. Data were collected for five subjects (average age of 28 ± 8 years and total body surface area burn of 69 ± 15%) who met the inclusion criteria. Changes in visceral protein levels were examined along with nitrogen balance and acute-phase reactants when the subjects were on enteral nutrition, and the proteins were not examined during times of acute kidney injury. Descriptive statistics were performed, and linear regression was used to analyze the association of visceral proteins and nitrogen balance during times that acute-phase reactant levels were decreasing. The subjects received an average of 3044 ± 1613 kcal/day (39 ± 20 kcal/kg), meeting 72% of caloric goals and achieving positive nitrogen balance during 68% of the 40 weekly measurements, with 174 ± 85 g of protein intake per day (2.2 ± 1.1 g/kg). There was a weak relationship between nitrogen balance and changes in visceral protein levels during times that the acute-phase reactant levels were decreasing (P > .05). Visceral proteins were found to be poor markers of nutritional status. This study is unique because the subjects were able to achieve positive nitrogen balance despite severe burns.

A pilot review of gradual versus goal re-initiation of enteral nutrition after burn surgery in the hemodynamically stable patient.

Severe weight loss resulting from inadequate nutritional intake along with the hypermetabolism after thermal injury can result in impaired immune function and delayed wound healing. This observational study was conducted on adults admitted between October 2007 and April 2012 with at least 20% total body surface area burn requiring excision who previously tolerated gastric enteral nutrition at calorie goal and who returned from surgery hemodynamically stable (no new pressor requirement) and compared the effect of goal rate re-initiation versus slow re-initiation after the first excision and grafting. Demographic, intake, and tolerance data were collected during the 36h following surgery and were analyzed with descriptive and comparative statistics. Data were collected on 14 subjects who met the inclusion criteria. Subjects in the goal rate re-initiation group (n=7) met a significantly greater percentage of caloric goals (99±12% versus 58±21%, p=0.003) during the 36h following surgery than subjects in the slow re-initiation group (n=7). There were no incidences of emesis, aspiration, or ischemic bowel in either group. The goal rate re-initiation group had a 29% incidence of either stool output >1L (n=1) or gastric residual volumes >500mL (n=1), whereas these were not present in the slow re-initiation group (p=0.462). In conclusion, in this small pilot study, we found that enteral nutrition could be re-initiated after the first excision and grafting in those patients who previously tolerated gastric enteral nutrition meeting caloric goals who return from surgery hemodynamically stable without a significant difference in intolerance and with a significantly higher percentage of calorie goals achieved, but larger studies are required.

Prevalence and impact of late defecation in the critically ill, thermally injured adult patient.

The aim of this study was to determine the prevalence of late defecation (absence of laxation for more than 6 days after admission) as an indicator of lower-gastrointestinal (GI) tract dysfunction in burn patients. In addition, the authors wanted to determine whether the addition of polyethylene glycol 3350 to the standard bowel regimen led to improvement in markers of lower-GI function and outcomes. The authors conducted a retrospective chart review of patients admitted to the burn intensive care unit during a 26-month period. Inclusion criteria were 20% or more TBSA burn, requirement for mechanical ventilation, and age over 18 years. Of 83 patients included, the prevalence of late defecation was 36.1% (n = 30). There was no association between late defecation and mortality. Patients with late defecation had more frequent episodes of constipation after first defecation (P =.03), of feeding intolerance (P =.007), and received total parenteral nutrition more frequently (P =.005). The addition of polyethylene glycol to the standard bowel regimen did not affect markers of lower-GI function. Late defecation occurs in more than one third of critically ill burn patients. Late defecation was associated with ongoing lower-GI dysfunction, feeding intolerance, and the use of total parenteral nutrition. The causal relationship between these problems has not been determined. A prospective study at the authors' institution is currently planned to attempt to validate late defecation as a marker of lower-GI tract dysfunction, determine its relationship to various outcomes, and determine risk factors for its development.

Signals from fat after injury: plasma adipokines and ghrelin concentrations in the severely burned.

INTRODUCTION: Hypermetabolism is universal in the severely burned and is characterized by catabolism of lean mass and body fat with associated insulin resistance. Adipokines are likely to play a role in these changes but have not been identified to date in burn patients. METHODS: From a single burn ICU, 17 burn patients with an expected stay>14 days were studied. Study period began within 14 days of admission. Over 7 days, plasma samples were collected for measurement of leptin, adiponectin, resistin, ghrelin, insulin, and cortisol by ELISA. For comparison, samples from 15 healthy controls of similar age, BMI, and blood glucose were obtained. RESULTS: Mean age was 33±17 years and BMI 26±3.4. Average burn size was 45±20% TBSA and ISS 32±10 with 72% having inhalation injury; in-hospital mortality was 29%. Estimated energy needs were 3626±710 kcal, of which 84±21% were met by enteral feeding with intensive insulin treatment (glucose 80-110 mg/ml). Using the homeostasis model assessment of insulin resistance, burned subjects were more resistant than controls (17±11.3 and 8±10.0). Insulin levels were elevated (57±35.6 µU/ml in burned subject vs. 26±31.1 µU/ml in controls), and cortisol concentrations increased (50±41.2 µg/dl vs. 12±3.9 µg/dl). These traditional hormone changes were associated with increased resistin (16.6±5.5 ng/ml vs. 3.8±0.9 ng/ml) and decreased leptin (8.8±8.9 ng/ml vs. 19.4±23.5 ng/ml), adiponectin (9±3.5 ng/ml vs. 17±10.2 ng/ml), and ghrelin (0.37±0.14 ng/ml vs.0.56±0.26 ng/ml). CONCLUSION: Patients with burns, who are characteristically hypermetabolic with hypercortisolism and insulin resistant, have significant changes in adipokine levels that appear independent of the magnitude of initial injury or metabolic derangement. In addition, suppression of ghrelin in the presence of decreased leptin and adiponectin levels in combination with increased insulin and resistin levels represent unexpected changes in the metabolic milieu of the injured patient possibly due to dramatic activation of inflammatory pathways, indicating strategies for treatment.

Determination of resting energy expenditure after severe burn.

The purpose of this study was to evaluate the accuracy of nine predictive equations for calculating energy expenditure in severely burned adult subjects. The selected equations have been reported as commonly used or determined to be the most accurate. This prospective, observational study was conducted on adult subjects admitted between October 2007 and July 2010 with ≥ 20% TBSA full-thickness burns (excluding electrical burns or severe head injury). Indirect calorimetry measurements were conducted as a convenience sample during the first 30 days after injury. Demographic data were collected, and resting energy expenditure was calculated using the nine selected predictive equations and compared to measured energy expenditure (MEE) using descriptive and comparative statistics. Data were collected on 31 subjects with an average age of 46 ± 19 years and %TBSA burn of 48 ± 21%. For all equations, slopes and intercepts were significantly different from the line of identity when compared with MEE. A calorie-dependent bias was present for all equations, in that lower calorie range was overestimated and the higher calorie range was underestimated. Only the Carlson and Milner equations had results that were not significantly different from the MEE and mean differences that were not significant in all burn size ranges. None of the equations had a strong correlation with MEE. Of the equations available, the Milner and Carlson equations are the most satisfactory in predicting resting energy expenditure in severely burned adults when indirect calorimetry is unavailable.