Comparison of normal infants and infants with cystic fibrosis using forced expiratory flows breathing air and heliox

Stephanie Davis, Marcus Jones, Jeffrey Kisling, John Howard, Robert S. Tepper

Research output: Contribution to journalArticle

22 Scopus citations


The detection of early airway disease in infants with cystic fibrosis (CF) may lead to earlier intervention and an improved prognosis. We hypothesized that the ratio of maximal expiratory flows while breathing a mixture of helium and oxygen (heliox) and air, referred to as density dependence (DD), would identify early airway disease in infants with CF who have normal lung function. We also hypothesized that these infants with CF might be better differentiated from normal infants when the flows breathing heliox are compared instead of room air flows. We evaluated 10 infants with CF and 21 infants without CF and with normal lung function, defined as a forced vital capacity (FVC) and forced expiratory flows between 25-75% of expired volume (FEF25-75) of greater than 70% predicted (z-score > - 2.0). Full forced expiratory maneuvers by the rapid thoracic compression technique were obtained while breathing room air and then heliox. Flow at 50% and 75% of expired volume (FEF50, FEF75), FEF25-75, and FVC were calculated from the flow volume curve with patients and control subjects breathing each gas mixture. The ratio of heliox to air flow at FEF50 and FEF75 was calculated (DD50, DD75), and the point where the two flow-volume curves crossed (VisoV') was also measured. DD parameters did not distinguish the infants with CF from the infants without CF; length-adjusted FEF50 breathing air was significantly lower in the infants with CF compared to the infants without CF (P < 0.05). Length-adjusted flows breathing heliox did not distinguish the two groups. We conclude that the lower FEF50 value may reflect early airway obstruction in healthy infants with CF, and that measurements obtained with the less dense gas mixture did not improve detection of airway disease in this age group.

Original languageEnglish (US)
Pages (from-to)17-23
Number of pages7
JournalPediatric pulmonology
Issue number1
StatePublished - Feb 26 2001


  • Cystic fibrosis
  • Early airway disease
  • Heliox
  • Infant

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Pulmonary and Respiratory Medicine

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