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Peripheral airway involvement in CF and asthma compared by inert gas washout
Author(s) -
Gustafsson Per M.
Publication year - 2007
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/ppul.20554
Subject(s) - nitrogen washout , bronchodilation , medicine , asthma , washout , cystic fibrosis , air trapping , ventilation (architecture) , cardiology , airway , anesthesia , lung volumes , functional residual capacity , lung , bronchodilator , mechanical engineering , engineering
Multiple‐breath N 2 washouts were performed before and after bronchodilation in 15 patients with moderately severe asthma (mean age 13 years), and in 11 patients with cystic fibrosis (CF; mean age 16 years) matched for FEV 1 . Eighteen healthy subjects (mean age 15 years) were studied before bronchodilation. The lung clearance index (LCI) was determined from the washout curve and gas trapping was assessed from five subsequent large breaths. Analysis of the progression of the concentration normalized phase III slopes (Sn III ) over the washout was used to determine inhomogeneity in the conducting airways (S cond ) and inhomogeneity close to or within the gas exchange zone (S acin ). Before bronchodilation all washout indexes were abnormal in the CF group, and all but S acin in the asthma group. Two indexes were higher in CF than in asthma: LCI (11.5 (3.3) vs. 8.7 (1.3); P < 0.01), and S acin (0.307 (0.207) vs. 0.142 (0.071); P < 0.01), while gas trapping indexes and S cond (0.151 (0.071) vs. 0.127 (0.041)) did not differ significantly. After bronchodilation, all indexes improved in asthma and only S cond remained abnormally elevated. In CF, only a modest but statistically significant S acin improvement was seen and all indexes stayed abnormal. The study shows that overall ventilation inhomogeneity and particularly inhomogeneity in or close to the gas exchange zone are more pronounced in CF than in asthma matched for FEV 1 , while inhomogeneity in the conducting airway zone is similar. After bronchodilation, residual abnormalities of airway function are seen all through the airway tree in CF but only in the conducting airways in asthma. Pediatr Pulmonol. 2007; 42:168–176. © 2006 Wiley‐Liss, Inc.