Bicarbonate kinetics and predicted energy expenditure in critically ill children

Jama Sy, Anand Gourishankar, William E. Gordon, Debra Griffin, David Zurakowski, Rachel M. Roth, Jorge Coss-Bu, Larry Jefferson, William Heird, Leticia Castillo

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Background: To determine nutrient requirements by the carbon oxidation techniques, it is necessary to know the fraction of carbon dioxide produced during the oxidative process but not excreted. This fraction has not been described in critically ill children. By measuring the dilution of 13C infused by metabolically produced carbon dioxide, the rates of carbon dioxide appearance can be estimated. Energy expenditure can be determined by bicarbonate dilution kinetics if the energy equivalents of carbon dioxide (food quotient) from the diet ingested are known. Objective: We conducted a 6-h, primed, continuous tracer infusion of NaH13CO3 in critically ill children fed parenterally or enterally or receiving only glucose and electrolytes, to determine bicarbonate fractional recovery, bicarbonate rates of appearance, and energy expenditure. Design: Thirty-one critically ill children aged 1 mo-20 y who were admitted to a pediatric intensive care unit at a tertiary-care center were studied. Patients were stratified by age, BMI, and severity score (PRISM III). Results: Fractional bicarbonate recovery was 0.69, 0.70, and 0.63, respectively, for the parenterally fed, enterally fed, and glucose-electrolytes groups, and it correlated with the severity of disease in the parenteral (P < 0.01) and glucose-electrolytes (P < 0.05) groups. Rates of appearance varied between 0.17 and 0.19 μmol · kg -1 · h-1 With these data and estimates of the energy equivalents of carbon dioxide (a surrogate for respiratory quotient), energy expenditure was determined. Conclusions: The 2001 World Health Organization and Schofield predictive equations overestimated and underestimated, respectively, energy requirements compared with those obtained by bicarbonate dilution kinetics. Bicarbonate kinetics allows accurate determination of energy needs in critically ill children.

Original languageEnglish (US)
Pages (from-to)340-347
Number of pages8
JournalAmerican Journal of Clinical Nutrition
Issue number2
StatePublished - Aug 1 2008
Externally publishedYes

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics


Dive into the research topics of 'Bicarbonate kinetics and predicted energy expenditure in critically ill children'. Together they form a unique fingerprint.

Cite this