Energy expenditure in ill premature neonates.

BACKGROUND/PURPOSE: The energy needs of critically ill premature neonates undergoing surgery remain to be defined. Results of studies in adults would suggest that these neonates should have markedly increased energy expenditures. To test this hypothesis, a recently validated stable isotopic technique was used to measure accurately the resting energy expenditure (REE) of critically ill premature neonates before and after patent ductus arteriosus (PDA) ligation.

METHODS

Six ventilated, fully total parenteral nutrition (TPN)-fed, premature neonates (24.5 plus minus 0.5 weeks' gestational age) were studied at day of life 7.5 plus minus 0.7, immediately before and 16 plus minus 3.7 hours after standard PDA ligation. REE was measured with a primed continuous infusion of NaH(13)CO(3), and breath samples were analyzed by isotope ratio mass spectroscopy. Serum CRP and cortisol concentrations also were obtained. Statistical analyses were made by paired sample t tests and linear regression.

RESULTS

The resting energy expenditures pre- and post-PDA ligation were 37.2 plus minus 9.6 and 34.8 plus minus 10.1 kcal/kg/d (not significant, P =.61). Only preoperative energy expenditure significantly (P <.01) predicted postoperative energy expenditure (R(2) = 88.0%). Pre- and postoperative determinations of CRP were 2.1 plus minus 1.5 and 7.1 plus minus 4.2 mg/dL (not significant, P =.34), and cortisol levels were 14.1 plus minus 2.3 and 14.9 plus minus 2.1 microgram/dL (not significant, P =.52).

CONCLUSIONS

Thus, critically ill premature neonates do not have elevated REE, and, further, there is no increase in REE evident the first day after surgery. This suggests that routine allotments of excess calories are not necessary either pre-or postoperatively in critically ill premature neonates. Given the high interindividual variability in REE, actual measurement is prudent if protracted nutritional support is required.