Early postoperative alterations in infant energy use increase the risk of overfeeding

Aim of Study: Energy needs in infants are decreased after surgery because of growth inhibition (resulting from catabolic stress metabolism), decreased insensible losses, and inactivity. Using standardized formulas that account for growth, activity, and insensible losses during this stress period can lead to overfeeding in excess of 200% of the actual measured requirement. Overfeeding during this acute injury period can result in increased CO 2 production from lipogenesis. This study determined the effects of a reduced rate of mixed caloric repletion on infant energy use during the early postoperative period. Methods: C-reactive protein (CRP), oxygen consumption (VO 2), carbon dioxide production (VCO 2), measured energy expenditure (MEE), and total urinary nitrogen (TUN) were measured serially in seven infants (average age, 78 days) during the first 72 hours after abdominal or thoracic surgery. Nonprotein respiratory quotient (RQ np), and values for oxidation of carbohydrate (C e) and fat (F e) were calculated. Injury severity was stratified based on serum CRP concentrations of ≥6.0 mg/dL (high stress) or 1.0) was significantly less likely in the resolving ( 2 6 studies, 33.4%) versus acute stress ( 9 13 studies, 69.2%, Z test P < .001) group. Five of seven ( 5 7 ) patients ( 9 19 individual studies) had negative F e values (average −9.89 ± 10.02) reflecting net lipogenesis. The RQ np for these nine studies was 1.14 ± 0.11 versus 0.97 ± 0.09 for the remaining 10, and this difference was significant ( P < .01). A significant correlation existed between carbohydrate intake and VCO 2 (Pearson r = .6951, P < .01). In addition, t