Comparison of helium dilution and nitrogen washout measurements of functional residual capacity in premature infants

Pediatr Pulmonol. 1993 Sep;16(3):197-200. doi: 10.1002/ppul.1950160310.


Comparison has been made of measurements of functional residue capacity (FRC) by a helium gas dilution (He) and a nitrogen washout (N2) technique. Twenty infants (median gestational age, 29.5 weeks) were studied at a median postnatal age of 25 days. No infant was oxygen dependent. The coefficient of repeatability of FRC (He) was 6.4 mL/kg and of FRC (N2), 6.3 mL/kg. The coefficient of repeatability of the two methods combined was 13.8 mL/kg. In 10 infants the results of two techniques differed by more than 20% of the mean FRC; those infants were born at a significantly earlier gestation than the rest of the cohort (P < 0.01). We conclude that, except in very immature infants, techniques for measuring FRC (He) and FRC (N2) yield reproducible and comparable results in convalescent premature infants.

Publication types

  • Clinical Trial
  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Female
  • Functional Residual Capacity / physiology*
  • Gestational Age
  • Helium*
  • Humans
  • Indicator Dilution Techniques*
  • Infant
  • Infant, Newborn
  • Infant, Premature / physiology*
  • Male
  • Nitrogen*
  • Reproducibility of Results


  • Helium
  • Nitrogen