Determinants of Skeletal Muscle Catabolism After Severe Burn

Abstract

ObjectiveTo determine which patient factors affect the degree of catabolism after severe burn. Summary Background DataCatabolism is associated with severe burn and leads to erosion of lean mass, impaired wound healing, and delayed rehabilitation. MethodsFrom 1996 to 1999, 151 stable-isotope protein kinetic studies were performed in 102 pediatric and 21 adult subjects burned over 20 -99.5% of their total body surface area (TBSA). Patient demographics, burn characteristics, and hospital course variables were correlated with the net balance of skeletal muscle protein synthesis and breakdown across the leg. Data were analyzed sequentially and cumulatively through univariate and cross-sectional multiple regression. ResultsIncreasing age, weight, and delay in definitive surgical treatment predict increased catabolism (P Ͻ .05). Body surface area burned increased catabolism until 40% TBSA was reached; catabolism did not consistently increase thereafter. Resting energy expenditure and sepsis were also strong predictors of net protein catabolism. Among factors that did not significantly correlate were burn type, pneumonia, wound contamination, and time after burn. From these results, the authors also infer that gross muscle mass correlates independently with protein wasting after burn. ConclusionsHeavier, more muscular subjects, and subjects whose definitive surgical treatment is delayed are at the greatest risk for excess catabolism after burn. Sepsis and excessive hypermetabolism are also associated with protein catabolism.The hypermetabolic response to severe burn trauma and sepsis is associated with increased energy expenditure and energy substrate release from protein and fat stores.

The Hepatic Response to Thermal Injury: Is the Liver Important for Postburn Outcomes?

“…Severe burns covering more than 40% of total body surface area (TBSA) typically are followed by a period of stress, inflammation, and hypermetabolism, characterized by a hyperdynamic circulatory response with increased body temperature, glycolysis, proteolysis, glycogenolysis, gluconeogenesis lipolysis, and futile substrate cycling (58)(59)(60). These responses are present in all trauma, surgical, or critically ill patients, but the severity, length, and magnitude is unique for burn patients (7).…”

“…Current understanding has been that these metabolic alterations resolve soon after complete wound closure. However, recent studies found that the hypermetabolic response to thermal injury may last for at least 12-36 months after the initial event (16,58,70,71).…”

The Pathophysiologic Response to Severe Burn Injury.

“…The intake was calculated as 1500 kcal/m 2 body surface + 1500 kcal/m 2 area burn as previously published. [13][14][15] The nutritional route of choice in our patient population was enteral nutrition via a duodenal (Dobhof) or nasogastric tube. Parenteral nutrition was only given in rare instances if the patient could not tolerate tube feeds.…”

“…Sepsis was defined as a positive blood culture or pathologic tissue identifying the pathogen during hospitalization or at autopsy, in combination with at least 3 of the following: leucocytosis or leucopenia (>12,000 or <4,000), hyperthermia or hypothermia (>38.5 or <36.5°C), tachycardia (>150 BPM in children), refractory hypotension (systolic BP <90 mmHg), thrombocytopenia (platelets <50,000/mm 3 ), hyperglycemia (serum glucose >240 mg/dl), and enteral feeding intolerance (residuals > 200 cc/hr or diarrhea > 1 L/day) as previously published. 13,14,16 We further determined time between operations as a measure for wound healing/re-epithelization. We propose that the time between operations was indicative when donor sites were healed and thereby allowed determination of wound healing.…”

Prognostic value of severity by various visceral proteins in critically ill patients with SIRS during 7 days of stay

“…Given the stress condition, the increased metabolic rate, energy expenditure and the increased protein catabolism, could lead to a negative nitrogen balance and high nutritional needs. Hence, protein catabolism is directly associated with elevated metabolic rate (9), related increased mortality rates and the period of time spent in an ICU stay (10). Therefore, the metabolism is not only affected by acute stress and inflammation but also by the nutritional status and comorbidities, the acute disease, and the phase of the acute disease.…”