title: Regional differences in bronchial reactivity assessed by respiratory impedance.
abstract: We used the Impulse Oscillometric System (IOS) to gain information concerning the distribution of hyper-reactivity along the bronchial tree during methacholine challenge test (MCT). 37 subjects underwent MCT until reaching the provocative dose (PD20). At each dose, we estimated respiratory resistance at 5 and 20Hz (R5, R20), and reactance at 5Hz (X5). In non-responsive subjects (N=14) no changes in R5, R20, and X5 were observed during MCT. In responsive subjects, a wide spectrum of responses was found concerning frequency dependence and PD20. We describe two phenotypes representing the extremes of response. For PD20>400μg (N=13), MCT caused equal changes of resistance/reactance on varying oscillation frequencies, suggesting a homogeneous bronchoconstriction along the bronchial tree. For PD20<200μg (N=10), a remarkable frequency dependence was observed, with increase in R5, no change in R20, and decrease in X5, suggesting hyper-responsiveness of the distal airways paralleled by a change in visco-elastic properties of lung parenchyma.
authors: Dept. of Health Sciences, University of Milano-Bicocca, 20900 Monza, Italy. Electronic address: egidio.beretta@unimib.it.
authors: Egidio
authors: E
authors: Beretta
authors: Clinica Pneumologica, University of Milano-Bicocca, San Gerardo Hospital, 20900 Monza, Italy.
authors: Francesco
authors: F
authors: Tana
authors: Dept. of Health Sciences, University of Milano-Bicocca, 20900 Monza, Italy.
authors: Gabriele Simone
authors: GS
authors: Grasso
authors: Dept. of Health Sciences, University of Milano-Bicocca, 20900 Monza, Italy.
authors: Manuela
authors: M
authors: Bartesaghi
authors: Clinica Pneumologica, University of Milano-Bicocca, San Gerardo Hospital, 20900 Monza, Italy.
authors: Luca
authors: L
authors: Novelli
authors: Clinica Pneumologica, University of Milano-Bicocca, San Gerardo Hospital, 20900 Monza, Italy.
authors: Alberto
authors: A
authors: Pesci
authors: Dept. of Health Sciences, University of Milano-Bicocca, 20900 Monza, Italy.
authors: Giuseppe
authors: G
authors: Miserocchi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology*; D016535:Bronchial Hyperreactivity / Q000175:diagnosis / Q000503:physiopathology*; D016085:Bronchoconstrictor Agents; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D012372:ROC Curve; D012119:Respiration / Q000187:drug effects; D012129:Respiratory Function Tests; D013147:Spirometry; D055815:Young Adult
chemical_list: D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride
keywords: Respiratory reactance, Asthma; Respiratory resistance; Sensitivity; Small airways; Specificity