The energy equations: development of equations for estimating energy expenditure in hospitalized patients

Commonly accepted formulae for estimating energy expenditures are based on data generated from normal volunteers. The applicability of such formulae to hospitalized patients is problematic. A recent advancement in the nutritional care of hospitalized patients has been the clinical application of indirect calorimetry for measurement of energy expenditure. The purpose of this study was to relate easily measured variables to measured energy expenditure (MEE) values of hospitalized patients in an attempt to derive an equation/equations for estimating energy expenditure. Height, age, sex, weight, obesity, ventilatory status, and diagnosis were correlated with the MEE's of 200 adult patients, using stepwise, multiple regression analysis. Two eqations were derived: EEE(v) = 1925 $-$ 10(A) + 5(W) + 281(S) + 292(T) + 851(B) EEE(s) = 629 $-$ 11(A) + 25(W) $-$ 609(O). Multiple R2 values for the two equations are 0.43 and 0.50, respectively. $\{$EEE = kcal/day, v = ventilator-dependent, s = spontaneously breathing, A = age (years), W = body weight (kg), S = sex (male = 1, female = 0), diagnosis of T = trauma, B = burn, O = obesity (present = 1, absent = 0)$\}$. The equations were tested prospectively on 100 patients. MEE's were not significantly different from EEE(s) or EEE(v) (paired t-tests, p $>$ 0.25). Energy expenditures can be accurately estimated in patients using easily obtained data and the above mentioned equations.