Premium
Peripheral airway function in childhood asthma, assessed by single‐breath He and SF 6 washout
Author(s) -
Ljungberg Henrik K.,
Gustafsson Per M.
Publication year - 2003
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.10356
Subject(s) - hyperventilation , medicine , spirometry , peripheral , asthma , airway obstruction , nitrogen washout , pulmonary function testing , ventilation (architecture) , washout , airway , cardiology , anesthesia , gastroenterology , lung , functional residual capacity , lung volumes , mechanical engineering , engineering
To assess whether the peripheral airways are involved in pediatric asthma, 10 asthmatic children (aged 8–15 years), hyperresponsive to dry‐air hyperventilation challenge (DACh), performed spirometry and a vital capacity He/SF 6 single‐breath washout test at rest, after DACh, and after beta 2 ‐therapy. The normalized phase III slopes (Sn III ) of the expired He and SF 6 concentrations served as measures of overall ventilation inhomogeneity, and the (SF 6 − He) Sn III difference served to indicate where along the peripheral airways obstruction occurs. While a greater increase in the He vs. SF 6 slope indicates that obstruction has occurred in the vicinity of the acinar entrance, the reverse suggests obstruction deeper in the intraacinar airways. The mean (SD) fall in FEV 1 after DACh was 35 (14)%. Both He and SF 6 Sn III increased significantly ( P < 0.05) after the challenge, and were restituted after beta 2 ‐therapy ( P < 0.05). After DACh, Sn III increased more for He than for SF 6 , resulting in a negative (SF 6 − He) Sn III difference ( P < 0.01), which was restituted after beta 2 ‐therapy ( P < 0.05). Even though there was no correlation between baseline FEV 1 and the magnitude of the subsequent fall in this parameter after DACh (r 2 = 0.04; n.s.), a strong correlation was found between the (SF 6 − He) Sn III difference at rest and its change after DACh (r 2 = 0.81; P < 0.001). We conclude that airways close to the acinar entrance participate in the airway response to DACh in asthmatic children. The magnitude of this peripheral airway response is related to the severity of resting peripheral airway dysfunction. Pediatr Pulmonol. 2003; 36:339–347. © 2003 Wiley‐Liss, Inc.