Do critically ill surgical neonates have increased energy expenditure?

BACKGROUND/PURPOSE: Adult metabolic studies suggest that critically ill patients have increased energy expenditures and thus require higher caloric allotments. To assess whether this is true in surgical neonates the authors utilized a validated, gas leak-independent, nonradioactive, isotopic technique to measure the energy expenditures of a stable postoperative group and a severely stressed cohort.

METHODS

Eight (3.46+/-1.0 kg), hemodynamically stable, total parenteral nutrition (TPN)-fed, nonventilated, surgical neonates (5 with gastroschisis, 2 with intestinal atresia, and 1 with intestinal volvulus) were studied on postoperative day 15.5+/-11.9. These were compared with 10 (BW = 3.20+/-0.2 kg), TPN-fed, extracorporeal life support (ECLS)-dependent neonates, studied on day of life 7.0+/- 2.8. Energy expenditure was obtained using a primed, 3-hour infusion of NaH(13)CO(3'), breath (13)CO(2) enrichment determination by isotope ratio mass spectroscopy, and the application of a standard regression equation. Interleukin (IL)-6 levels and C-reactive protein (CRP) concentrations were measured to assess metabolic stress. Comparisons between groups were made using 2 sample Student's t tests.

RESULTS

The mean energy expenditure was 53+/-5.1 kcal/kg/d (range, 45.6 to 59.8 kcal/kg/d) for the stable cohort and 55+/-20 kcal/kg/d (range, 32 to 79 kcal/kg/d) for the ECLS group (not significant, P =.83). The IL-6 and CRP levels were significantly higher in the ECLS group (29 +/-11.5 v 0.7+/-0.6 pg/mL [P<.001], and 31+/-22 v 0.6+/-1.3 mg/L [P<.001], respectively). Mortality rate was 0% for the stable postoperative patients and 30% for the ECLS group.

CONCLUSIONS

Severely stressed surgical neonates, compared with controls, generally do not show increased energy expenditures as assessed by isotopic dilution methods. These data suggest that the routine administration of excess calories may not be warranted in critically ill surgical neonates and support the hypothesis that neonates obligately redirect energy, normally used for growth, to fuel the stress response. This is a US government work. There are no restrictions on its use.