Use of [13C]Bicarbonate for Metabolic Studies in Preterm Infants: Intragastric versus Intravenous Administration

Department of Pediatrics, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands.
Pediatric Research (Impact Factor: 2.31). 12/2005; 58(5):861-4. DOI: 10.1203/01.PDR.0000181374.73234.80
Source: PubMed


The metabolic fate of substrates in humans can be examined by the use of stable isotopes, one of which, [13C]bicarbonate, may serve to estimate CO2 production rate. In view of minimizing the burden of metabolic studies for preterm infants, the authors determined whether intragastric and intravenous infusions of [13C]bicarbonate would achieve the same 13CO2 enrichment in expired air during steady state. A second aim of this study was to determine the minimum time required to reach steady state during intragastric infusion. Ten preterm infants received a primed continuous [13C]bicarbonate infusion intragastrically, followed by an intravenous infusion the next day. Breath samples were obtained every 30 min by the direct sampling method. 13CO2 isotopic enrichment, expressed as atom percent excess, was measured by isotopic ratio mass spectrometry. Two-tailed t tests were used to detect statistically significant differences between the infusion routes. The isotopic enrichment at plateau did not differ between intragastric and intravenous infusion. A steady state of 13CO2 enrichment was achieved after 60 min of intravenous infusion and after 120 min of intragastric infusion. In conclusion, intragastric infusion of [13C]bicarbonate may serve to estimate the whole-body CO2 production rate in preterm infants. To reach 13CO2 steady state, a minimum of 120 min of bicarbonate administration is required.

Download full-text


Available from: Gardi Voortman,
16 Reads
  • Source
    • "Sodium bicarbonate- 13 C has been used as a tracer probe both by the oral and the intravenous (iv) route of administration in the sodium bicarbonate- 13 C-breath test (SBT) for numerous clinical applications—predicting hypercapnia [65] [143], energy expenditure [144] [145] [146], atrophic gastritis [147], to estimate the whole-body CO 2 production rate [148] gastric emptying time [149] and total parenternal nutrition [150]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Diagnostic (13)C-stable isotope probes are currently being expanded in their scope, to provide precise evaluations of the presence or absence of etiologically significant changes in metabolism due to a specific disease or the lack of a specific enzyme. The salient features of the (13)C-breath test are that they are non-invasive, non-radioactive, safe, simple, and effective. The simplicity of the (13)C-breath test makes it very applicable in a clinical setting: the physician can obtain valuable diagnostic information by distinguishing between two groups or populations on the basis of the recovery of (13)CO(2) from the ingested (13)C-substrate. The breath tests can also be used to monitor the progress of disease severity or to evaluate the efficacy of medications. This review concentrates on current research in the medical field dedicated to the metabolite (13)C-labelled carbon dioxide in exhaled air following ingestion of (13)C-labelled substrates.
    Journal of Breath Research 09/2007; 1(1):014003. DOI:10.1088/1752-7155/1/1/014003 · 4.63 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The portal-drained viscera (stomach, intestine, pancreas and spleen) have a much higher rate of both energy expenditure and protein synthesis than can be estimated on the basis of their weight. A high utilization rate of dietary nutrients by the portal-drained viscera might result in a low systemic availability which determines whole-body growth. From studies in our multiple catheterized piglet model, we conclude that more than half of the dietary protein intake is utilized within the portal-drained viscera and that amino acids are a major fuel source for the visceral organs. Specific stable isotope studies reveal that there are large differences in the utilization rate amongst the different amino acids. The majority of the results obtained from the piglet studies can be extrapolated to the human (preterm) infant. First-pass, splanchnic uptake of lysine and threonine differ substantially, while non-essential amino acids are oxidized to a great extend in the human gut. Overall, these studies indicate that gut amino acid metabolism has a great impact on systemic availability and hence growth in the neonate.
    Nestle Nutrition workshop series. Paediatric programme 02/2006; 58:95-102; discussion 102-8. DOI:10.1159/000095023
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cyst(e)ine can be synthesized de novo from methionine and serine and is, therefore, a nonessential amino acid in human adults. Several studies have suggested that cyst(e)ine might be a conditionally essential amino acid in preterm infants because of biochemical immaturity. No data are available on cyst(e)ine requirements in low-birth-weight (LBW) preterm infants. The aim was to determine cyst(e)ine requirements in LBW infants with gestational ages from 32 to 34 wk, measured 1 mo after birth with the use of the indicator amino acid oxidation technique. LBW infants were randomly assigned to 1 or 2 of the 5 formulas containing graded cystine concentrations (11, 22, 32, 43, or 65 mg cyst(e)ine/100 mL) and generous amounts of methionine. After 24-h adaptation, cyst(e)ine requirement was determined by (13)CO(2) release from [1-(13)C]phenylalanine in expired breath. (13)CO(2) enrichment was measured by isotopic ratio mass spectrometry. Cyst(e)ine requirement was determined in 25 LBW infants with a mean (+/-SD) gestational age of 33 +/- 1 wk and birth weight of 1.78 +/- 0.32 kg. Fractional oxidation of [1-(13)C]phenylalanine did not differ between the 5 groups. There is no evidence for limited endogenous cyst(e)ine synthesis in 4-wk-old LBW preterm infants born at gestational ages from 32 to 34 wk. It is safe to conclude that the cyst(e)ine requirement is <18 mg kg(-1) d(-1) providing generous amounts of methionine and that cyst(e)ine is probably not a conditionally essential amino acid in fully enterally fed LBW preterm infants born at 32-34 wk.
    American Journal of Clinical Nutrition 10/2007; 86(4):1120-5. · 6.77 Impact Factor
Show more