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Titolo:
Homeokinesis and short-term variability of human airway caliber
Autore:
Que, CL; Kenyon, CM; Olivenstein, R; Macklem, PT; Maksym, GN;
Indirizzi:
McGill Univ, Royal Victoria Hosp, Montreal Chest Inst,Meakins Christie Labs, Inspiraplex Resp Hlth Network Ctr Excellence, Montreal, PQ H2X 2P4, Canada McGill Univ Montreal PQ Canada H2X 2P4 ence, Montreal, PQ H2X 2P4, Canada Dalhousie Univ, Sch Biomed Engn, Halifax, NS B3J 3H5, Canada Dalhousie Univ Halifax NS Canada B3J 3H5 ngn, Halifax, NS B3J 3H5, Canada
Titolo Testata:
JOURNAL OF APPLIED PHYSIOLOGY
fascicolo: 3, volume: 91, anno: 2001,
pagine: 1131 - 1141
SICI:
8750-7587(200109)91:3<1131:HASVOH>2.0.ZU;2-5
Fonte:
ISI
Lingua:
ENG
Soggetto:
SMOOTH-MUSCLE; PULMONARY RESISTANCE; BRONCHIAL-ASTHMA; DEEP INHALATION; BRONCHOCONSTRICTION; FLOW; DYNAMICS;
Keywords:
asthma; frequency distributions; respiratory impedance; airway smooth muscle; smooth muscle velocity of shortening; asthma prognosis; homeostasis; entropy; airway obstruction; complexity;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
39
Recensione:
Indirizzi per estratti:
Indirizzo: Macklem, PT Montreal Chest Inst, Inspiraplex, 3650 St Urbain, Montreal, PQH2X 2P4, Canada Montreal Chest Inst 3650 St Urbain Montreal PQ Canada H2X 2P4
Citazione:
C.L. Que et al., "Homeokinesis and short-term variability of human airway caliber", J APP PHYSL, 91(3), 2001, pp. 1131-1141

Abstract

We hypothesized that short-term variation in airway caliber could be quantified by frequency distributions of respiratory impedance (Zrs) measured athigh frequency. We measured Zrs at 6 Hz by forced oscillations during quiet breathing for 15 min in 10 seated asthmatic patients and 6 normal subjects in upright and supine positions before and after methacholine (MCh). We plotted frequency distributions of Zrs and calculated means, skewness, kurtosis, and significance of differences between normal and log-normal frequency distributions. The data were close to, but usually significantly different from, a log-normal frequency distribution. Mean lnZrs in upright and supine positions was significantly less in normal subjects than in asthmatic patients, but not after MCh and MCh in the supine position. The lnZrs SD (a measure of variation), in the upright position and after MCh was significantly less in normal subjects than in asthmatic patients, but not in normal subjects in the supine position and after MCh in the supine position. We conclude that 1) the configuration of the normal tracheobronchial tree is continuously changing and that this change is exaggerated in asthma, 2) in normal lungs, control of airway caliber is homeokinetic, maintaining variation within acceptable limits, 3) normal airway smooth muscle (ASM) when activated and unloaded closely mimics asthmatic ASM, 4) in asthma, generalized airway narrowing results primarily from ASM activation, whereas ASM unloading by increasing shortening velocity allows faster caliber fluctuations, 5) activation moves ASM farther from thermodynamic equilibrium, and 6) asthma maybe a low-entropy disease exhibiting not only generalized airway narrowing but also an increased appearance of statistically unlikely airway configurations.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 19/01/20 alle ore 11:56:23