| The relationship between wheezing and lung mechanics during methacholine-induced bronchoconstriction in asthmatic subjects. | |
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MedLine Citation:
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PMID: 8756796 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Wheeze is a classic sign of airflow obstruction but relatively little is known of its mechanism of production or its relationship to the development of airflow obstruction. We studied eight asthmatic subjects age (mean +/- 5D) 42 +/- 5 yr, FEV1 2.46 +/- 0.36 L during an extended, symptom-limited methacholine challenge test. Breath sounds were detected by a microphone over the right upper anterior chest. Spectral analysis was by a fast Fourier transform algorithm. Mean FEV1 fell by 51 +/- 14% to 1.28 +/- 0.61 L during the challenge and airways resistance increased by 119 +/- 50%. There were no consistent changes in breathing pattern or tidal volume during the challenge. Wheeze occurred late in the challenge at the highest concentration of methacholine administered and only after expiratory tidal flow limitation had been reached. Five subjects developed wheeze on tidal breathing, the remaining three only wheezed on deep breathing. Wheezing sounds were reproducible between breaths, coefficient of variation of starting sound frequency was 4.2% and ending frequency 12%. Mean frequency of expiratory wheezes was 669 +/- 100 Hz and inspiratory wheezes 710 +/- 76 Hz. Expiratory wheeze fell in pitch during a breath (mean fall in sound frequency 187 +/- 43 Hz) but inspiratory wheezes were more variable. Expiratory wheezes occurred late in the respiratory cycle at a mean of 58% of the maximal tidal expiratory flow, whereas inspiratory wheezes occurred around maximal tidal inspiratory flows, suggesting that the mechanisms of production of inspiratory and expiratory wheezes may be different. In this model, the presence of wheeze during tidal breathing was a sign of severe airflow limitation. |
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Authors:
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D P Spence; D R Graham; G Jamieson; B M Cheetham; P M Calverley; J E Earis |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: American journal of respiratory and critical care medicine Volume: 154 ISSN: 1073-449X ISO Abbreviation: Am. J. Respir. Crit. Care Med. Publication Date: 1996 Aug |
Date Detail:
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Created Date: 1996-10-24 Completed Date: 1996-10-24 Revised Date: 2004-11-17 |
Medline Journal Info:
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Nlm Unique ID: 9421642 Medline TA: Am J Respir Crit Care Med Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 290-4 Citation Subset: AIM; IM |
Affiliation:
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Aintree Chest Centre, Fazakerley Hospital, Liverpool, United Kingdom. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Asthma / diagnosis, physiopathology* Bronchial Provocation Tests Bronchoconstriction / physiology Bronchoconstrictor Agents / diagnostic use Fourier Analysis Humans Maximal Expiratory Flow-Volume Curves / physiology Methacholine Chloride / diagnostic use Pulmonary Ventilation / physiology Respiratory Mechanics / physiology* Respiratory Sounds / physiopathology* Signal Processing, Computer-Assisted Tidal Volume / physiology |
| Chemical | |
Reg. No./Substance:
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0/Bronchoconstrictor Agents; 62-51-1/Methacholine Chloride |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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