Resting Energy Expenditure After Fontan Surgery in Children With Single-Ventricle Heart Defects

Abstract

Background: Data on resting energy expenditure (REE) and oxygen consumption (VO₂) after pediatric cardiopulmonary bypass (CPB) will facilitate optimal nutrient prescription. Methods: The authors measured continuous REE and VO₂, using an in-line indirect calorimetery (IC) in 30 consecutive children with single-ventricle physiology immediately after Fontan surgery. REE during steady state at 8 hours after surgery was compared with standard equation-estimated energy expenditure (EEE). Patients were classified into 3 groups: hypermetabolic (measured REE [MREE]/EEE ratio >1.2), hypometabolic (MREE/EEE ratio <0.8), and normometabolic (MREE/EEE ratio 0.8–1.2). Demographic, anthropometric, and perioperative clinical characteristics were examined for their correlation with metabolic status. Results: In 26 of 30 patients with completed IC, mean REE at 8 hours after surgery was 57 ± 20 kcal/kg/d, and mean VO₂ was 110 ± 35 mL/min. Mean values of VO₂ and REE did not change within the first 24 hours after surgery. There was poor correlation between MREE at 8 hours and the EEE using the World Health Organization equation (r = 0.32, P = .11). Most patients (n = 19, 73%) were either normometabolic or hypometabolic. Lack of hypermetabolism was significantly associated with higher intraoperative serum lactate level and positive fluid balance compared with the rest of the group. Conclusions: The authors report a low prevalence of hypermetabolism in children with single-ventricle defects after Fontan surgery. Measured REE had poor correlation with equation-estimated energy expenditure in a majority of the cohort. The absence of increased energy expenditure after CPB will influence energy prescription in this group.