Enteral Nutritional Support and Wound Excision and Closure Do Not Prevent Postburn Hypermetabolism as Measured by Continuous Metabolic Monitoring

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Abstract
Estimation of nutritional needs in burn patients is difficult. In 24 severely burned patients, we measured CO2 production and O2 consumption continuously during their period of mechanical ventilation. Patients with extensive burns were placed on a continuous metabolic monitor (CMM) (Puritan Bennett Co., Kingwood, TX), and metabolic expenditure was recorded each 24 hours. High protein enteral feedings were started within several hours of admission, and administration rates were adjusted to meet daily caloric demands as determined by the CMM. Full-thickness wounds were excised as early as patient condition permitted, and wounds were closed with autograft, allograft, or TransCyte (Advanced Tissue Sciences Inc., La Jolla, CA). Daily 24-hour caloric needs as measured by CMM were compared with baseline caloric needs predicted by the Harris-Benedict equation and also compared with actual daily caloric intake. Patients were removed from study when they were off continuous mechanical ventilation. A total of 24 patients were studied, with a mean age of 46 years and a 44% total body burn size (partial- and full-thickness). All full-thickness burns were completely excised by a mean of 6.5 days postburn. Mean daily energy expenditures remained elevated through the duration of the study period (42 days), with a mean elevation of 184.9% of baseline as predicted by Harris-Benedict equation. Patients received enteral feedings, which met 99.4% of actual caloric needs as predicted by CMM during the study period. Continuous metabolic monitoring demonstrates that early wound excision and wound closure, coupled with aggressive enteral nutritional support with high protein formulas, do not prevent the marked hypermetabolism that accompanies thermal injury.