A NEW EQUATION TO PREDICT THE RESTING ENERGY-EXPENDITURE OF SURGICAL INFANTS

It is essential that adequate calories are provided to newborns to cover their energy expenditure. This is difficult to measure and varies significantly between individuals. The aim of this study was to develop an equation to predict the basal energy requirements of stable surgical infants, using easily measurable parameters. Resting energy expenditure (REE) was measured using computerized open-circuit indirect calorimetry. One hundred twenty-two measurements were made on different days in 46 stable nonventilated infants. The measured REE was 34.41 ± 0.46 cal/kg/min; (mean ± SEM). Three body-size measurements correlated significantly with REE (cal/min): weight in kilograms (r = .87; P < .00001), body surface area in square meters (r = .86; P < .00001), and lean body mass in kilograms (r = .81; P < .00001). Five other independent variables correlated significantly with REE (cal/kg/min): heart rate in beats per minute (r = .60; P < .00001), postnatal age in days (r = .49; P < .00001), caloric intake in cal/kg/min (r = .44; P < .00001), gestational age in weeks (r = .43; P < .00001), and rectal temperature in degrees Celsius (r = .19; P = .04). Weight, heart rate, age, gestational age, and temperature were regarded as independent predictor variables of REE for the multiple stepwise regression analysis. Three variables entered this highly significant equation: REE (cal/min) = -74.436 + (34.661 × weight in kg) + (0.496 × heart rate in beats/min) + (0.178 × age in days) (r = .92; F = 230.07; significance, F < .00001). Thirteen additional studies were performed on nine stable surgical infants to test the validity of this equation. The correlation between predicted and measured REE was 0.89. The error in predicting REE from the equation was -.95 ± 3.65%. © 1994.