Measurement of carbon dioxide production in very low birth weight babies

C. C. Kingdon, F. Mitchell, O. A.F. Bodamer, A. F. Williams

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Background - CO2 production is most commonly measured by using indirect calorimetry to quantify elimination of CO2 in breath (V(co)2). An alternative is to measure the rate at which CO2 appears in the body pool (Raco2) by infusing a 13C labelled bicarbonate tracer. V(co)2 and Raco2 generally differ but are related by c, a factor that adjusts for the incomplete recovery of infused tracer in the breath. The literature relating to human studies cites a wide range of values for c but the only neonatal study to determine c empirically estimated a mean value of 0.77. Aim - To estimate fractional recovery rate, c, in very low birthweight babies, and assess the feasibility of using the isotopic technique to measure CO2 production during mechanical ventilation. Method - Eleven spontaneously breathing, continuously fed, very low birthweight infants (median birth weight 1060 g, median gestational age 29 weeks) were studied. Results - Mean (SD) V(co)2 was 9.0 (2.0) ml/min (standard temperature and pressure dry, STPD) and mean (SD) Raco2 was 9.6 (2.1) ml/min (STPD). The mean (SD) value of c was estimated as 0.95 (0.13). The 95% confidence intervals of the mean were 0.87-1.03. Conclusions - The results emphasise the importance of measuring c for a given study population rather than assuming a value based on adult studies. The close approximation of Raco2 and V(co)2 in this group of babies implies that the labelled bicarbonate infusion technique could be used to measure simply CO2 production during mechanical ventilation.

Original languageEnglish (US)
Pages (from-to)F50-F55
JournalArchives of Disease in Childhood: Fetal and Neonatal Edition
Issue number1
StatePublished - 2000


  • Calorimetry
  • Carbon dioxide
  • Carbon isotopes
  • Very low birthweight babies

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health


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