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Comparison of normal infants and infants with cystic fibrosis using forced expiratory flows breathing air and heliox *
Author(s) -
Davis Stephanie,
Jones Marcus,
Kisling Jeffrey,
Howard John,
Tepper Robert S.
Publication year - 2001
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/1099-0496(200101)31:1<17::aid-ppul1002>3.0.co;2-8
Subject(s) - heliox , medicine , cystic fibrosis , vital capacity , lung volumes , breathing , anesthesia , breathing gas , pulmonary function testing , cardiology , airway , lung , lung function , diffusing capacity
Summary . 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 (FEF 25–75 ) 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 (FEF 50 , FEF 75 ), FEF 25–75 , 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 FEF 50 and FEF 75 was calculated (DD 50 , DD 75 ), and the point where the two flow‐volume curves crossed (V iso V′) was also measured. DD parameters did not distinguish the infants with CF from the infants without CF; length‐adjusted FEF 50 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 FEF 50 value may reflect early airway obstruction in healthy infants with CF, and that measurements obtained with the less dense gas mixture did not improve detec‐tion of airway disease in this age group. Pediatr Pulmonol. 2001; 31:17–23. © 2001 Wiley‐Liss, Inc.