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Energy expenditure in ill premature neonates
Jennifer J Garza1, Stephen B Shew, Tamir H Keshen
1Department of Surgery, Children's Hospital, Harvard Medical School, Boston, MA, USA.
Insights
Critically ill premature neonates undergoing surgery do not have elevated resting energy expenditure (REE). Measuring REE is recommended for prolonged nutritional support due to individual variability.
Area of Science:
- Neonatal intensive care
- Pediatric surgery
- Metabolic research
Background:
- Energy needs in critically ill premature neonates undergoing surgery are not well-defined.
- Adult studies suggest significantly increased energy expenditures in similar patient populations.
- Accurate measurement of resting energy expenditure (REE) is crucial for appropriate nutritional support.
Purpose of the Study:
- To accurately measure the resting energy expenditure (REE) in critically ill premature neonates before and after patent ductus arteriosus (PDA) ligation.
- To test the hypothesis that these neonates have markedly increased energy expenditures.
- To determine if surgical intervention (PDA ligation) impacts REE.
Main Methods:
- Utilized a validated stable isotopic technique (primed continuous infusion of NaH(13)CO(3)) to measure REE.
- Studied six ventilated, total parenteral nutrition (TPN)-fed premature neonates (24.5 ± 0.5 weeks gestational age) on day of life 7.5 ± 0.7.
- Measured REE immediately before and 16 ± 3.7 hours after PDA ligation, also analyzing serum CRP and cortisol levels.
Main Results:
- Pre- and post-PDA ligation REE were not significantly different (37.2 ± 9.6 vs. 34.8 ± 10.1 kcal/kg/d, P =.61).
- Preoperative REE significantly predicted postoperative REE (R(2) = 88.0%).
- No significant changes were observed in C-reactive protein (CRP) or cortisol levels post-surgery.
Conclusions:
- Critically ill premature neonates do not exhibit elevated REE, even after surgery.
- Increased caloric support is not routinely necessary pre- or postoperatively in this population.
- Actual REE measurement is advisable for protracted nutritional support due to high interindividual variability.
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.