Bronchodilator Response in Patients with Persistent Allergic Asthma Could Not Predict Airway Hyperresponsiveness
© Canadian Society of Allergy and Clinical Immunology 2007
Published: 15 December 2007
Anticholinergics, or specific antimuscarinic agents, by inhibition of muscarinic receptors cause bronchodilatation, which might correlate with activation of these receptors by the muscarinic agonist methacholine. The aim of this study was to determine whether a positive bronchodilator response to the anticholinergic ipratropium bromide could predict airway hyperresponsiveness in patients with persistent allergic asthma. The study comprised 40 patients with mild and moderate persistent allergic asthma. Diagnosis was established by clinical and functional follow-up (skin-prick test, spirometry, bronchodilator tests with salbutamol and ipratropium bromide, and methacholine challenge testing). The bronchodilator response was positive to both bronchodilator drugs in all patients. After salbutamol inhalation, forced expiratory volume in 1 second (FEV1) increased by 18.39 ± 6.18%, p < .01, whereas after ipratropium bromide, FEV1 increased by 19.14 ± 6.74%, p < .01. The mean value of FEV1 decreased by 25.75 ± 5.16%, p < .01 after methacholine (PC20 FEV1 [provocative concentration of methacholine that results in a 20% fall in FEV1] from 0.026 to 1.914 mg/mL). Using linear regression, between methacholine challenge testing and bronchodilator response to salbutamol, a positive, weak, and stastistically significant correlation for FEV1 was found (p < .05). Correlations between methacholine challenge testing and the bronchodilator response to ipratropium bromide were positive and weak but not statistically significant. The positive bronchodilator response to ipratropium bromide could not predict airway hyperresponsiveness.
Keywordsairway hyperresponsiveness allergic asthma bronchodilator response ipratropium bromide methacholine challenge testing salbutamol
Airway hyperresponsiveness in asthma is characterized by an increased sensitivity and an increased maximal response to a variety of bronchoconstrictor agents [1–4]. It is known that inflammatory processes have been associated with the presence of airway hyperresponsiveness in subjects with asthma [5, 6]. Airway hyperresponsiveness can be quantified by measuring the dose or concentration of inhaled methacholine or histamine that causes a 20% decrease in forced expiratory volume in 1 second (FEV1) (PC20FEV1 [provocative concentration of methacholine that results in a 20% fall in FEV1]).
Neural mechanisms have long been regarded as factors contributing to the pathogenesis of asthma and involved in airway hyperresponsivenes, a hallmark of asthma . Cholinergic nerves play an important role in the regulation of airway calibre in many species, including humans, and they form the dominant constrictor mechanism in the airways. Preganglionic and postganglionic parasympathetic nerves release acethylcholine. Anticholinergics, or muscarinic antagonists, by inhibition of muscarinic receptors cause bronchodilatation, which might correlate with activation of these receptors by the muscarinic agonist methacholine.
Bronchodilator responsiveness and bronchoconstrictor responsiveness have been considered physiologic opposites in patients with obstructive airway disease. The study by Douma and colleagues suggested that bronchoconstrictor responsiveness and bronchodilator responsiveness are not highly correlated .
We hypothesized whether the bronchodilator response to anticholinergic ipratropium bromide correlates better with methacholine challenge testing than the bronchodilator response to the β2 agonist salbutamol in patients with persistent allergic asthma. If this is true, it would mean that a positive bronchodilator response to ipratropium bromide could predict a positive bronchoconstrictor response to methacholine in patients with persistent allergic asthma. If so, another diagnostic tool for asthma could be established that is simpler and cheaper, and thus more widely acceptable, than the procedure for methacholine challenge testing.
Today, we are aware of a certain number of asthmatic patients who do not have a positive bronchodilator response to short-acting β2 agonists, such as salbutamol, perhaps even 20% of them, owing to a β2 agonist receptor gene polymorphism. In this light, an alternative measure of airway response, besides the bronchodilatator test with a short-acting β2 agonist, seems more important. Because methacholine challenge testing is a costly and time-consuming procedure, and the safety of both patients and technicians should be considered in the design of the test room and the test procedures, we hypothesized that another diagnostic test, a bronchodilatator test with an anticholinergic agent, could replace it concerning the possibility of increased airway sensitivity detection as a hallmark of asthma. To test this hypothesis, we decided to perform serial lung function testing with different agents on subjects with persistent allergic asthma with the purpose of finding the best correlation between them. The simplicity and safety of the bronchodilator test with ipratropium bromide versus a methacholine challenge warrants this evaluation.
Patients and Methods
The study was performed at the Outpatient Centre for Diseases of the Respiratory System in Zagreb. The Ethics Committee approved the study.
The study comprised 40 patients with persistent allergic asthma, 23 males and 17 females, aged 16 to 65 years (34.40 ± 14.16). A diagnosis of asthma was established according to The Global Initiative on Asthma (GINA) classification : 34 patients had GINA II, mild persistent asthma (peak expiratory flow (PEF) or FEV1 ≥ 80% of predicted, variability 20-30%), and 6 patients had GINA III, moderate persistent asthma (PEF or FEV1 ≥ 70% of predicted).
None of the patients had used inhaled or oral corticosteroids, long-acting bronchodilators, theophyllines, antihistamines, sodium cromoglycate, or nedocromil sodium for at least 4 weeks preceding the study. Shortacting bronchodilators were not used for at least 12 hours before pulmonary function testing. Current or ex-smokers, pregnant women, and patients with cardiovascular disease, rhinosinusitis, or respiratory tract infections during the 4 weeks before the study were excluded.
Patients with inclusion criteria were recruited into the study one after another by the time of arrival at the outpatient centre during 2 autumn months.
Each patient underwent pulmonary function testing (spirometry, bronchodilator tests with salbutamol and ipratropium bromide), methacholine challenge testing, and the skin-prick test.
Skin-prick tests were performed with standard airborne allergens [10, 11]: house dust mite (Dermatophagoides pteronyssinus), feathers, mould, dog and cat epithelium, mixed tree pollen, mixed grass pollen, and mixed weed pollen. A mean wheal diameter ≥ 3 mm of control solution was considered positive.
A Pneumo Screen spirometer (Jaeger, Germany) was used for pulmonary function tests. The observed parameters were the FEV1 and the forced vital capacity (FVC). Forced expiratory manoeuvres were repeated until three measurements of FEV1 reproducible to 100 mL were obtained; the larger FEV1 value was used in analysis. Reference values are those of the European Community for Coal and Steel, CECA II .
On the first day, spirometry with a bronchodilator test with salbutamol was performed. After baseline spirometry, subjects inhaled 400 μg of metered dose inhaler (MDI) salbutamol (Ventolin, Pliva, Zagreb, Croatia). Spirometry was repeated after 20 minutes.
On the second day, spirometry with an ipratropium bromide test was performed. After baseline spirometry, subjects inhaled 80 μg of MDI ipratropium bromide (Atrovent, Boehringer Ingelheim, Ingelheim am Rhein, Germany). Spirometry was repeated after 45 minutes.
A reversibility test was considered positive if there was a 12% increase in FEV1 and/or FEV1 = 200 mL compared with prebronchodilator FEV1 expressed as a percentage of predicted value .
On the third day, methacholine challenge testing was performed by the standardized 2-minute tidal breathing method [14, 15] using a Pneumo Screen spirometer and Pari Provocation Test I. Without a bronchodilator, the baseline FEV1 had to be more than 70% of the predicted value [13, 16]. Doubling concentrations of methacholine (acetyl-β-methacholine chloride, Janssen Pharmaceutics, Belgium) ranging between 0.03 and 8 mg/mL were given by inhalation at intervals of 5 minutes, each for a period of 2 minutes, after the first inhalation of normal saline. FEV1 was measured after each inhalation. If methacholine did induce a drop of 20% or more, the intrapolated concentration at which a 20% drop in FEV1 had occurred was calculated and termed the PC20FEV1.
Statistical analysis of the data was performed by using a paired t-test. The results are expressed as mean ± SD. Methacholine PC20 was calculated from the log concentration-response curves by linear interpolation of the two adjacent data points. All PC20 values were log-transformed before analysis. Analyses were performed using linear regression for correlations between the log-transformed PC20 values and both bronchodilator test values.
Forty patients with persistent allergic asthma were included in the study. In all patients, the skin-prick test was positive. Dermatophagoides pteronyssinus was the most positive single allergen (37 of 40).
Baseline Characteristics of Patients with Persistent Allergic Asthma
Baseline FEV1 %
Baseline FVC %
Sensitization to 1 allergen
Sensitization to 2 to 5 allergens
Our results showed a positive bronchodilator response to salbutamol in all patients with persistent allergic asthma. After salbutamol inhalation, the mean value of FEV1 increased by 18.39 ± 6.18% (from 12.40 to 35.60%). The mean value of FVC increased by 7.96 ± 6.96% Both spirometric values (FEV1 and FVC) were significantly higher after the bronchodilator test (p < .01).
The bronchodilator response to ipratropium bromide was also positive in all patients with persistent allergic asthma. The mean value of FEV1 increased by 19.14 ± 6.74% (from 12.10 to 37.20%). The mean value of FVC increased by 8.74 ± 6.98%. Spirometric values for FVC and FEV1 were significantly higher after ipratropium bromide inhalation (p < .01).
All patients with persistent allergic asthma had positive methacholine challenge testing. The mean value of FEV1 decreased by 25.75 ± 5.16% (from 20.20 to 40.40%) after inhalation concentrations between 0.03 and 2.0 mg/mL of methacholine (PC20FEV1 from 0.026 to 1.914 mg/mL). Spirometric parameters were significantly lower (p < .01) after methacholine challenge testing.
Percentage of Increase for Parameter FEV1 after the Bronchodilator Test with Salbutamol and Ipratropium Bromide and PC20FEV1 after Methacholine Challenge Testing
Salbutamol % of Increase FEV 1
Ipratropium % of Increase FEV 1
PC 20 FEV 1 mg/mL
Correlations between methacholine challenge testing and bronchodilator response to salbutamol and ipratropium bromide for FVC were positive, weak, and statistically not significant. The correlation between methacholine challenge testing and the bronchodilator response to salbutamol for FEV1 was positive, weak, and statistically significant (p < .05). The correlation between methacholine challenge testing and the bronchodilator response to ipratropium bromide for FEV1 was positive, very weak, and statistically not significant.
This study has measured the acute bronchodilator effect of an inhaled anticholinergic agent (ipratropium bromide) in 40 subjects with persistent allergic asthma to determine if a positive bronchodilator response predicts the presence of airway hyperresponsiveness. Methacholine chloride is a synthetic derivate of acetylcholine, which is a parasympathetic neurotransmitter that is very important for airway smooth muscle tone. As anticholinergic agents (such as ipratropium) act through the same neural pathway as methacholine but in opposite directions, we were interested in whether there is a correlation between bronchoconstrictor and bronchodilator response in airways.
In our patients with allergic asthma, FEV1 increased by 18.39% after salbutamol inhalation, whereas after ipratropium, FEV1 increased by 19.14%. Our results correspond to the results of other authors who have proven reversibility to bronchodilators in patients with asthma [8, 13, 14]. A positive bronchodilator response to ipratropium bromide indicates that patients with persistent allergic asthma have increased cholinergic tone .
Change in FEV1 is the primary outcome measure for methacholine challenge testing . All asthmatics had positive methacholine challenge testing. After inhalation concentrations between 0.03 and 2.0 mg/mL of methacholine (PC20FEV1 from 0.026 to 1.914 mg/mL), the mean value of FEV1 decreased by 25.75% (from 20.20 to 40.40%).
In this study, the correlation between a pre- and a postbronchodilator response to salbutamol and methacholine challenge testing for parameter FEV1 (p < .05) was proven significant. There was no significant correlation between the pre- and postbronchodilator response to ipratropium bromide and methacholine challenge testing for FEV1. Our main finding was that a positive bronchodilator response to ipratropium bromide did not predict a positive methacholine hyperresponsiveness test.
The study by Douma and colleagues showed a lack of correlation between bronchoconstrictor response and bronchodilator response in a population-based study . Bronchoconstrictor responsiveness and bronchodilator responsiveness are two different phenotypic markers that are not interchangeable in epidemiologic studies. The absence of bronchodilator responsiveness does not imply the absence of bronchoconstrictor responsiveness, even in individuals with airway obstruction.
It is not surprising that application of an anticholinergic drug to predict methacholine-induced bronchoconstriction in this study has failed given the complexity of chronic airway inflammation and remodelling in asthma, even if the activity of allergy-related airway inflammation is known.
In this study, responses to salbutamol are better correlated with the methacholine response than responses to ipratropium. Anticholinergic therapy may prevent only the bronchoconstrictor component resulting from a cholinergic reflex, not the direct effects of bronchoconstrictor mediators, in contrast to β-adrenergic agonists, which reverse bronchoconstriction irrespective of mechanism because they are functional antagonists. Ipratropium bromide is a non-selective anticholinergic drug because it blocks not only M3 receptors but also the prejunctional M2 receptors . Inhibition of the M2 receptors leads to more acetylcholine release during cholinergic nerve stimulation, which may overcome postjunctional blockade. Thus, the non-selective cholinergic antagonists may be less efficient than selective M3 receptor antagonists. Recent data show that the long-acting muscarinic antagonist tiotropium bromide could inhibit smooth muscle-specific myosin expression, which also inhibits the increase in and contractility of airway smooth muscle mass and remodelling, and prevent airway hyperresponsiveness .
The β2 agonists produce bronchodilatation by direct stimulation of β2 receptors on airway smooth muscle, leading to relaxation. But β2 adrenoceptors, through which salbutamol acts, are desensitized in asthma, in part owing to the inflammatory effect of cysteinyl leukotrienes . In addition, there are over 100 different inflammatory mediators that modulate airway smooth muscle tone in humans. It is well known that mediators of allergic reaction, such as cysteinyl leukotrienes and endothelin, could increase bronchial muscle hypertrophy . It is also known that salbutamol could prevent bronchoconstriction owing to cysteinyl leukotrienes, whereas this is not the case with anticholinergics . Salbutamol is a potent bronchodilator, but it could also inhibit cysteinyl leukotriene synthesis by the airway cells .
Asthma is a complex disorder with a different disease pattern and a different response to therapy, depending on the combination of asthma genotype and phenotype in each patient. It is worth the effort to perform the study with a larger number of asthma patients to determine what happens in those asthmatics with a negative bronchodilator response to salbutamol. Futher studies must investigate if ipratropium bronchodilator testing results in asthmatics with a negative salbutamol test (and probably with a gene polymorphism for the β2 agonist receptor) could produce more useful data concerning asthma diagnosis, therapy benefit, and prognostic value.
- Barnes PJ: New concepts in the pathogenesis of bronchial hyperresponsiveness and asthma. J Allergy Clin Immunol. 1989, 83: 1013-26. 10.1016/0091-6749(89)90441-7.View ArticlePubMedGoogle Scholar
- Cockcroft DW, Davis BE: Mechanisms of airway hyperresponsiveness. J Allergy Clin Immunol. 2006, 118: 551-9. 10.1016/j.jaci.2006.07.012.View ArticlePubMedGoogle Scholar
- Bousquet J, Jeffery PK, Busse WW: Asthma from bronchoconstiction to airways inflammation and remodeling. Am J Respir Crit Care Med. 2000, 161: 1720-45.View ArticlePubMedGoogle Scholar
- O'Byrne PM, Inman MD: Airway hyperresponsiveness. Chest. 2003, 123 (Suppl 3): 411-6. 10.1378/chest.123.3_suppl.411S.View ArticleGoogle Scholar
- Fireman P: Understanding asthma pathophysiology. Allergy Asthma Proc. 2003, 24: 79-83.PubMedGoogle Scholar
- Bjornsdottir US, Cypcar DM: Asthma: an inflammatory mediator soup. Allergy. 1999, 54 (Suppl 49): 55-61. 10.1111/j.1398-9995.1999.tb04389.x.View ArticlePubMedGoogle Scholar
- Widdicombe JG: The neuronal component of asthma. Agents Actions. 1989, 213-24. Suppl 28
- Douma WR, Gooijer de A, Rijcken B: Lack of correlation between bronchoconstrictor response and bronchodilator response in a population based study. Eur Respir J. 1997, 10: 2772-7. 10.1183/09031936.97.10122772.View ArticlePubMedGoogle Scholar
- Global Initiative for Asthma: Global Strategy for Asthma Management and Prevention, workshop report. National Heart, Lung and Blood Institute and World Health Organization. 2006, Bethesda (MD): National Institutes of Health, NIH Publication No.: 96-3659 BGoogle Scholar
- Bernstein IL, Storms WW: Summary statements of practice parameters for allergy diagnostic tests. Ann Allergy Asthma Immunol. 1995, 75: 543-52.PubMedGoogle Scholar
- Nelson HS: Quality assurance in allergy skin testing. Ann Allergy. 1993, 71: 3-4.PubMedGoogle Scholar
- Report of the Working Party of the European Community for Coal and Steel. Standardization of Lung Function Tests. Bull Eur Physiopathol Respir. 1983, 19 (Suppl 5): 3-38.
- Quanjer PH, Tammeling GJ, Cotes JE: Lung volumes and forced ventilatory flows. Eur Respir J. 1993, 6 (Suppl 16): 5-40.View ArticlePubMedGoogle Scholar
- Sterk PJ, Fabbri LM, Quanjer PH: Airway responsiveness. Standardized challenge testing with pharmacological, physical and sensitizing stimuli in adults. Eur Respir J. 1993, 4 (Suppl 16): 53-83.View ArticleGoogle Scholar
- American Thoracic Society: Guidelines for methacholine and exercise challenge testing - 1999. Am J Respir Crit Care Med. 2000, 161: 309-29.View ArticleGoogle Scholar
- Scott GC, Braun SR: A survey of the current use and methods of analysis of bronchoprovocational challenges. Chest. 1991, 100: 322-8. 10.1378/chest.100.2.322.View ArticlePubMedGoogle Scholar
- Butorac-Petanjek B, Popović-Grle S, Pelicarić D: Cholinergic tone and airway hyperresponsiveness in patients with persistent allergic asthma. Eur Respir J. 2006, 28 (Suppl 50): 219-Google Scholar
- Chinn S, Burney PGJ, Britonn JR: Comparison of PD20 with two alternative measures of response to histamine challenge in epidemiological studies. Eur Respir J. 1993, 6: 670-9.PubMedGoogle Scholar
- Barnes PJ: Muscarinic receptor subtypes in airways (editorial; comments). Eur Respir J. 1993, 6: 328-31.PubMedGoogle Scholar
- Gosens R, Bos IS, Zaagsma J: Protective effects of tiotropium bromide in the progression of airway smooth muscle remodeling. Am J Respir Crit Care Med. 2005, 171: 1096-102. 10.1164/rccm.200409-1249OC.View ArticlePubMedGoogle Scholar
- Rovati GE, Baroffio M, Citro S: Cysteinyl-leukotrienes in the regulation of beta2-adrenoceptor function: an in vitro model of asthma. Respir Res. 2006, 7: 103-10.1186/1465-9921-7-103.PubMed CentralView ArticlePubMedGoogle Scholar
- Martin JG, Ramos-Barbon D: Airway smooth muscle growth from the perspective of animal models. Respir Physiol Neurobiol. 2003, 137: 251-61. 10.1016/S1569-9048(03)00151-4.View ArticlePubMedGoogle Scholar
- Tsuji T, Kato T, Kimata M: Differential effects of beta-2 adrenoreceptor desensitization on the Ig-E-dependent release of chemical mediators from cultured human mast cells. Biol Pharm Bull. 2004, 27: 1549-54. 10.1248/bpb.27.1549.View ArticlePubMedGoogle Scholar
- Yang XX, Ho G, Xu LJ: The beta (2)-agonist salbutamol inhibits bronchoconstriction and leukotriene (D4) synthesis after dry gas hyperpnea in the guinea-pig. Pulm Pharmacol Ther. 1999, 12: 325-9. 10.1006/pupt.1999.0215.View ArticlePubMedGoogle Scholar