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Refractory period during provocation with eucapnic hyperventilation and methacholine.
- Source :
-
American journal of respiratory and critical care medicine [Am J Respir Crit Care Med] 1994 Jun; Vol. 149 (6), pp. 1452-6. - Publication Year :
- 1994
-
Abstract
- Eucapnic voluntary hyperventilation (EVH) and methacholine inhalation challenge (MIC) both cause bronchoconstriction in asthmatics. A refractory period, or time when the response to bronchoprovocation in a series of challenges is diminished, has been found after hyperventilation or exercise but not after MIC. We investigated whether EVH or MIC blunted the response to the other test. Sixteen asthmatics were studied on 2 d, taking both tests each day. They were randomized to either EVH or MIC first on Day 1, then the opposite order on Day 2, 6 to 14 d apart. After EVH as a first test, the mean decline in FEV1 from baseline was 18.66 +/- 4.76% (mean +/- SEM), but when EVH followed MIC, the response to EVH was reduced by 30%, to a decline in FEV1 of only 13.02 +/- 3.75% (p = 0.0026). During MIC, the mean provocation dose to cause 20% decrease in FEV1 (PD20) given as the initial challenge was 54.77 +/- 21.60 breath units, compared with 46.94 +/- 19.55 breath units when MIC followed EVH (p = 0.54). However, the subset of patients most sensitive to methacholine (PD20 < 0.1 breath unit) had changes suggestive of a refractory period after EVH, with a mean increase in the PD20 from 0.06 +/- 0.01 to 3.35 +/- 1.43 (p = 0.069). Our data show that MIC attenuates the response to subsequent challenge with EVH. Conversely, EVH may only affect subsequent MIC in those most sensitive to methacholine.
- Subjects :
- Adult
Aged
Analysis of Variance
Bias
Bronchial Provocation Tests methods
Constriction, Pathologic
Female
Forced Expiratory Volume
Humans
Male
Middle Aged
Sensitivity and Specificity
Time Factors
Vital Capacity
Asthma diagnosis
Asthma physiopathology
Bronchial Provocation Tests standards
Carbon Dioxide
Hyperventilation complications
Methacholine Chloride
Subjects
Details
- Language :
- English
- ISSN :
- 1073-449X
- Volume :
- 149
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- American journal of respiratory and critical care medicine
- Publication Type :
- Academic Journal
- Accession number :
- 8004298
- Full Text :
- https://doi.org/10.1164/ajrccm.149.6.8004298