Standardized Equations Underestimate Nutrition Needs in Burn and Complex Wounds Patients

Traditionally, standardized equations are used to estimate caloric requirements of burn patients; however, these equations do not account for differences in physiology or injury characteristics. Due to the substantial metabolic derangement caused by burns and large wounds, patients are often in a prolonged hypermetabolic state, increasing caloric needs. Because of the inability of standardized equations to adapt to hypermetabolic changes, we hypothesized that predicted caloric requirements underreport caloric needs compared with measured requirements by an indirect calorimeter (IC). We conducted a retrospective observational study of the IC measurements conducted at our Burn Center and compared the results to the predicted caloric requirements determined by standardized equation (Harris Benedict, Schofield, or Mifflin-St Jeor). Comparisons between equations and IC measurements were represented using Intraclass Correlation Coefficient (ICC) and Bland-Altman plots; all analysis was considered unpowered and exploratory. Thirty-five IC measurements were conducted on 20 heterogenous patients with a median age of 45 years. Each measurement pair consisted of a predicted daily caloric need as determined by the appropriate standardized equation and measured caloric need determined by IC. In total, it was found that standardized equations underreported caloric need by 29.37%, with an ICC of 0.70, 95% CI (0.49-0.84), representing moderate agreement between predictive equations and IC measurements. While unpowered, this data suggests that IC better represents the hypermetabolic response in burn and wound patients in comparison to standardized equations.