Objective: To assess the measured resting energy expenditure pattern over time in a group of critically ill children who were admitted to a pediatric intensive care unit and to determine whether a hypermetabolic response, i.e., >10% above predicted, occurred in a pattern similar to that observed in adults. A secondary aim was to compare the accuracy of a newly derived prediction equation specific to the pediatric intensive care unit and the measured resting energy expenditure.
Design: A prospective, clinical, observational study.
Setting: A pediatric intensive care unit of a tertiary care medical center.
Patients: Forty-four children (29 males, 15 females) ages 2 wks to 17 yrs.
Measurements and main results: During the course of their stay in the pediatric intensive care unit, 44 patients' measured resting energy expenditure was assessed using indirect calorimetry 94 times at up to three time points. The first measurement was at a mean time of 25 +/- 10 (+/-sd) hrs after admission, the second at 73 +/- 16 hrs, and the third immediately before discharge, which occurred at a mean of 193 +/- 93 hrs after admission. Measured energy expenditure varied only slightly (7% to 10%) from the first to second and the second to third measurements. Evidence for hypermetabolism was not apparent. Generally, the prediction equations performed well. Mean measured resting energy expenditure for all measurements was 821 +/- 653 kcals/24 hrs. The Schofield equation estimate was 798 +/- 595 kcals/24 hrs and the White equation estimate was 815 +/- 564 kcals/24 hrs (p = not significant). Nineteen (20%) measurements were >110% above the age-appropriate Schofield-predicted equation, and 30 measurements (32%) were <90% below that predicted by Schofield. Consequently, 45% of measured resting energy expenditure measurements were within 90% to 110% of that predicted by the Schofield equation. The White equation was inaccurate (not within 10% of measured resting energy expenditure) in 66 of 94 measurements (70%). The discrepancy was greatest (100%) in children with measured resting energy expenditure <450 kcal/24 hrs.
Conclusion: The hypermetabolic response apparent in adults was not evident in these critically ill children. Currently available prediction equations cannot substitute for indirect calorimetry measurement of energy expenditure in guiding nutritional support in pediatric intensive care units.