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Repeatability of methacholine challenges in 2 to 4‐year‐old children with asthma, using a new technique for quantitative delivery of aerosol
Author(s) -
Klug Bent,
Bisgaard Hans
Publication year - 1997
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/(sici)1099-0496(199704)23:4<278::aid-ppul5>3.0.co;2-i
Subject(s) - medicine , repeatability , asthma , methacholine , aerosol , respiratory disease , immunology , statistics , lung , mathematics , physics , meteorology
To determine the repeatability of bronchial responsiveness in awake young children, two methacholine challenge tests were performed on separate days in 16 children with stable asthma (mean age, 3¾ years). Methacholine was administered using a new method for quantitative delivery of aerosol that eliminates the effect of dilution of the aerosol by entrainment of air and enables quantitative delivery of aerosol according to body weight. Respiratory function was monitored by measurement of respiratory resistance by the interrupter technique (Rint), respiratory resistance and reactance at 5 Hz (Rrs5, Xrs5) by the impulse oscillation technique, transcutaneous measurements of oxygen (PtcO 2 ), and specific airway resistance (sRaw). Repeatability was evaluated by determining the provocative dose that caused a defined percentage of change relative to baseline (PD%: Rint PD 30 , Rrs5 PD 30 , Xrs5 PD 30 , PtcO 2 PD 10 , and sRaw PD 50 . Repeatability was estimated from the difference between the PD % obtained at the time of the two tests. Using the numeric value of these differences, the repeatability of Xrs5 PD 80 , PtcO 2 PD 10 , and sRaw PD 50 was [mean (SD)]: [0.8 (0.5)] [0.5 (0.4)] and [0.7 (0.6)] doubling doses, respectively. Rint PD 30 and Rrs5 PD 30 proved to be less reproducible: [1.2 (1)] and [1.6 (0.9)] doubling doses, respectively. The new method of aerosol delivery offers a means of standardizing the bronchoconstrictor stimulus, and the results show that estimates of bronchial responsiveness in young children can be obtained reproducibly within one doubling dose of methacholine. Pediatr. Pulmonol. 1997;23:278–286. © 1997 Wiley‐Liss, Inc.