Challenge of predicting resting energy expenditure in children undergoing surgery for congenital heart disease.

OBJECTIVES

To determine pre- and postoperative predictors of energy expenditure in children with congenital heart disease requiring open heart surgery; and to compare measured resting energy expenditure with current predictive equations.

DESIGN

Prospective resting energy expenditure data were collected, using indirect calorimetry, for ventilated children admitted consecutively to the pediatric intensive care unit after surgery for congenital heart disease. A 30-min steady-state measurement was performed in suitable patients. Resting energy expenditure was compared to pre- and postoperative clinical variables, and to predicted energy expenditure, using currently used predictive equations.

SETTING

Pediatric intensive care unit at the Royal Brompton Hospital, London.

PATIENTS

Children ventilated in the pediatric intensive care unit post surgery for congenital heart disease.

INTERVENTIONS

Measurement of energy expenditure by indirect calorimetry.

MEASUREMENTS AND MAIN RESULTS

Twenty-one mechanically ventilated children (n = 17 boys, 4 girls) were enrolled in the study. Mean +/- sd measured resting energy expenditure was 67.8 +/- 15.4 kcal/kg/day. Most children had inadequate delivery of nutrients compared with actual requirements. Cardiopulmonary bypass had a significant influence on energy expenditure after surgery; in patients who underwent cardiopulmonary bypass during surgery, mean resting energy expenditure was 73.6 +/- 14.45 kcal/kg/day vs. 58.3 +/- 10.29 kcal/kg/day in patients undergoing nonbypass surgery. Children who were malnourished preoperatively had greater resting energy expenditure postoperatively. There was also a significant difference between measured energy expenditure and the Schofield (p = .006), World Health Organization (p = .002), and pediatric intensive care unit-specific formula (p < .0001). However, energy expenditure or a relative energy deficit in the early postoperative period was not associated with severity or duration of organ dysfunction.

CONCLUSIONS

Poor nutritional status preoperatively and cardiopulmonary bypass were associated with a greater energy expenditure post cardiac surgery. None of the current predictive equations predicted energy requirements within acceptable clinical accuracy.