Bronchial responsiveness to methacholine in chronic bronchitis: Relationship to airflow obstruction and cold air responsiveness

Department of Medicine, McMaster University, Hamilton, Ontario, Canada
Thorax (Impact Factor: 8.29). 01/1985; 39(12):912-8. DOI: 10.1136/thx.39.12.912
Source: PubMed


The response to inhaled methacholine is increased in patients with chronic airflow obstruction, but it is not known whether this is due to true hyperresponsiveness or is a result of the airflow obstruction. In asthmatics the response to methacholine correlates with the bronchoconstriction produced by hyperventilation of cold dry air. We studied 27 patients with a history of smoking and chronic bronchitis with a range of severity of airflow obstruction. Bronchial responses to methacholine (expressed as the provocation concentration causing a fall in FEV1 of 20%-PC20) and isocapnic hyperventilation of cold dry air were measured. In 19 patients the PC20 was less than 8 mg/ml (that is, in the asthmatic range) but only three developed bronchoconstriction in response to hyperventilation. There was a linear correlation between the log PC20 and the FEV1 (r = 0.86, p less than 0.001). The results suggest that in patients with chronic airflow obstruction the response to methacholine is determined by the degree of airflow obstruction, and cannot be used in the diagnosis of asthma in the absence of additional information.

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Available from: Robin S Roberts, Aug 18, 2014
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    • "The prevalence of BHR after hyperventilation of cold air was previously reported to be approximately 15 % of smokers with chronic bronchitis or COPD. However, responses to challenge were measured by means of FEV1, which may underestimate the true response [25]; this could explain the low proportion of responders among smokers upon indirect challenge in previous studies [10, 26, 27]. Therefore, the large variability in BHR prevalence might depend at least partly on the methodological limitations of the forced expiration technique, since airway tonus may change after a deep inspiration that precedes the FEV1 maneuver [28, 29]. "
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    ABSTRACT: Background Disabling respiratory symptoms and rapid decline of lung function may occur in susceptible tobacco smokers. Bronchial hyperresponsiveness (BHR) elicited by direct challenge methods predicts worse lung function outcomes. The aim of this study was to evaluate whether BHR to isocapnic hyperventilation of dry air (IHDA) was associated with rapid deterioration in airway status and respiratory symptoms. Methods One hundred twenty-eight smokers and 26 age- and sex-matched healthy individuals with no history of smoking were investigated. All subjects completed a questionnaire. Spirometry and impulse oscillometry (IOS) measurements were recorded before and after 4 min of IHDA. The tests were repeated after 3 years in 102 smokers and 11 controls. Results Eighty-five smokers (66 %) responded to the challenge with a ≥2.4-Hz increase in resonant frequency (Fres), the cutoff limit defining BHR, as recorded by IOS. They had higher Fres at baseline compared to nonresponding smokers [12.8 ± 3.2 vs. 11.5 ± 3.4 Hz (p < 0.05)] and lower FEV1 [83 ± 13 vs. 89 ± 13 % predicted (p < 0.05)]. Multivariable logistic regression analysis indicated that wheezing (odds ratio = 3.7, p < 0.01) and coughing (odds ratio = 8.1, p < 0.05) were significantly associated with hyperresponsiveness. An increase in Fres was recorded after 3 years in responding smokers but not in nonresponders or controls. The difference remained when subjects with COPD were excluded. Conclusions The proportion of hyperresponsive smokers was unexpectedly high and there was a close association between wheezing and coughing and BHR. Only BHR could discriminate smokers with rapid deterioration of airway status from others.
    Full-text · Article · Jan 2013 · Beiträge zur Klinik der Tuberkulose
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    • "In contrast, defining reversibility as the increase in percent predicted FEV 1 is a better way to discriminate asthma from COPD [2] [3]. One study [8] reported that an improvement in the percent predicted FEV 1 of 10% had a specificity of 0.95 for asthma versus chronic bronchitis. An increase of 15% of the predicted value had a specificity of 1 for asthma. "
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    ABSTRACT: Although the term "all that wheezes is not asthma" is not new, and the long list of asthma masqueraders has remained essentially the same for several decades, the importance of knowing when to question the accuracy ofa diagnosis of asthma has remained critical for physicians who care for patients with respiratory symptoms. The concepts of "asthma control" and"asthma severity" are currently evolving, although the fundamental hall-marks that define the syndrome of asthma endure and should be mastered by asthma specialists. Asthma masqueraders, including several that may confound a correct diagnosis of asthma, are important to consider when either the presentation of asthma is atypical or the response of the patient to treatment is suboptimal. COPD and VCD head the list of diagnoses most likely to be confused with asthma in everyday practice. Correctly identifying the diagnosis of COPD enables implementation of an up-to-date treatment plan that differs from asthma management. VCD is a vastly under recognized syndrome whose existence is widely accepted but whose pathophysiology is poorly understood, and correctly identifying a VCD component to asthma symptoms enables both a reduction in costly and potentially harmful asthma medications and focus on specific VCD treatment, such as speech therapy. For less common and uncommon asthma masqueraders, it is important to be familiar with their typical clinical presentation and basic diagnostic approaches.
    Full-text · Article · Feb 2006 · Medical Clinics of North America
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    • "In this context, the advantage of assessing AHR in suspected cases of COPD could be provided by more specific aspects of AHR, such as exaggerated airway narrowing. Many investigators have clearly demonstrated that the outcome of the bronchoprovocation test depends on the pre-challenge lung function (Ryan et al 1982; Ramsdale et al 1984; Verma et al 1988; Sterk and Bel 1989). In other words, the lower the baseline FEV1, the higher the magnitude of AHR. "
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    ABSTRACT: COPD represents one of the leading causes of mortality in the general population. This study aimed at evaluating the relationship between airway hyperresponsiveness (AHR) and COPD and its relevance for clinical practice. We performed a MEDLINE search that yielded a total of 1919 articles. Eligible studies were defined as articles that addressed specific aspects of AHR in COPD, such as prevalence, pathogenesis, or prognosis. AHR appears to be present in at least one out of two individuals with COPD. The occurrence of AHR in COPD is influenced by multiple mechanisms, among which impairment of factors that oppose airway narrowing plays an important role. The main determinants of AHR are reduction in lung function and smoking status. We envision a dual role of AHR: in suspected COPD, specific determinants of AHR, such as reactivity and the plateau response, may help the physician to discriminate COPD from asthma; in definite COPD, AHR may be relevant for the prognosis. Indeed, AHR is an independent predictor of mortality in COPD patients. Smoking cessation has been shown to reduce AHR. Further studies are needed to elucidate whether this functional change is associated with improvement in lung function and respiratory symptoms.
    Preview · Article · Feb 2006 · International Journal of COPD
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