The bias flow nitrogen washout technique for measuring the functional residual capacity in infants

M. G. Morris, P. Gustafsson, R. Tepper, M. Gappa, J. Stocks

Research output: Contribution to journalArticle

56 Scopus citations


The functional residual capacity (FRC) is the most commonly measured static lung volume in infants. It is important for interpreting volume-dependent pulmonary mechanics, e.g. airway resistance, and defining normal lung growth. The bias flow nitrogen washout technique is widely used for measuring FRC because the dead space and circuit resistance are low, making it suitable for small or sick infants. Moreover, data acquisition and calculation are easily programmed for a personal computer. The aim of this paper is to provide recommendations pertaining to equipment requirements, study procedures and reporting of data for functional residual capacity measurements. While measuring the functional residual capacity is regarded as physiologically and clinically important, the accuracy of the measurement is undoubtedly equally important. Hence, the paper also emphasizes factors influencing the accuracy of functional residual capacity measurements independent of equipment requirements. These recommendations represent the "State of the Art" in 2000.

Original languageEnglish (US)
Pages (from-to)529-536
Number of pages8
JournalEuropean Respiratory Journal
Issue number3
StatePublished - Jul 12 2001
Externally publishedYes


  • Functional residual capacity
  • Gas dilution
  • Infant
  • Lung volume
  • Nitrogen washout
  • Respiratory function tests

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

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