Perception Of Bronchoconstriction Research Articles

Perception of Bronchoconstriction Following Methacholine and Eucapnic Voluntary Hyperpnea Challenges in Elite Athletes

Self-reported respiratory symptoms are poor predictors of exercise-induced bronchoconstriction (EIB) in athletes. The objective of this study was to determine whether athletes have an inadequate perception of bronchoconstriction. One hundred thirty athletes and 32 nonathletes completed a standardized questionnaire and underwent eucapnic voluntary hyperpnea (EVH) and methacholine inhalation test. Perception scores were quoted on a modified Borg scale before each spirometry measurement for cough, breathlessness, chest tightness, and wheezing. Perception slope values were also obtained by plotting the variation of perception scores before and after the challenges against the fall in FEV1 expressed as a percentage of the initial value [(perception scores after - before)/FEV1]. Up to 76% of athletes and 68% of nonathletes had a perception score of ≤0.5 at 20% fall in FEV1 following methacholine. Athletes with EIB/airway hyperresponsiveness (AHR) had lower perception slopes to methacholine than nonathletes with asthma for breathlessness only (P=.02). Among athletes, those with EIB/AHR had a greater perception slope to EVH for breathlessness and wheezing (P=.02). Female athletes had a higher perception slope for breathlessness after EVH and cough after methacholine compared with men (P<.05). The age of athletes correlated significantly with the perception slope to EVH for each symptom (P<.05). Minimal differences in perception of bronchoconstriction-related symptoms between athletes and nonathletes were observed. Among athletes, the presence of EIB/AHR, older age, and female sex were associated with slightly higher perception scores.

Perception of Bronchoconstriction: A Complementary Disease Marker in Children with Asthma

Introduction. Asthma guidelines use symptoms as the most important aspect of asthma control. Symptom perception varies widely between individuals. Over-perception as well as underperception of bronchoconstriction could have a negative effect on asthma management. We hypothesized that perception of bronchoconstriction in childhood asthma is not related to common measures of disease control. For that reason, we examined the clinical determinants of the perception of bronchoconstriction and the repeatability of perception measurements. Patients and methods. In school-age children with moderately severe atopic asthma, we measured the perception of bronchoconstriction (decrease in forced expiratory volume in 1 second (FEV1)) during methacholine bronchoprovocation challenges. The perception of bronchoconstriction was assessed as the slope of the relation between FEV1 and Borg score, and as the Borg score at a 20% decrease in FEV1 from baseline during the provocation test (PS20). Data from subjects who had a 20% or more decrease in FEV1 (n = 112) were used for the analysis. Fifty-four children repeated the test after 3 months. Symptoms, use of rescue medication, and peak expiratory flows were scored in diaries during the 2 weeks before testing. Results. Symptom perception was significantly better in children without (PD20 > 1570 μg, n = 28) than in children with airway hyperresponsiveness (PD20 ≤ 1570 μg, n = 112), slope 0.22 versus 0.13 respectively (p < .001). Borg scores correlated with PD20 (p = .01), baseline FEV1 (only for slope, p = .04), and use of rescue beta agonist (p = .01), but not with other aspects of asthma control. Repeatability of Borg scores was good (slope: R = 0.59, PS20: R = 0.52). Conclusion. Poorer symptom perception in asthmatic children correlated with hyperresponsiveness, and was associated with lower baseline FEV1 and less use of rescue bronchodilators. This suggests that the measurement of symptom perception should be taken into account in individual management plans for children with asthma.CATO Study Group Members: Department of Pediatric Respiratory Medicine, Haga Hospital/Juliana Children’s Hospital, The Hague (M. Nuijsink, M.D., J. M. Kouwenberg, M.D.). Department of Epidemiology and Biostatistics, Erasmus University Medical Center, Rotterdam (W. C. J. Hop, Ph.D.). Department of Respiratory Medicine, Academic Medical Centre, University, Amsterdam (Prof. P. J. Sterk, Ph.D.). Leiden University Medical Center, Leiden (E. R. V. M. Rikkers-Mutsaerts, M.D.). Department of Pediatric Respiratory Diseases, University Medical Center Groningen (Prof. E. J. Duiverman, M.D., Ph.D.). Department of Pediatric Respiratory Medicine, Erasmus University Medical Center/Sophia Children’s Hospital, Rotterdam (Prof. J. C. de Jongste, M.D., Ph.D.). Asthma Center Heideheuvel, Hilversum (O. H. van der Baan-Slootweg, M.D., E. E. M. van Essen-Zandvliet, M.D., Ph.D.). Flevo Hospital, Almere (N. J. van den Berg, M.D., Ph.D.). Prof. Dr. J. M. Boogaard, Ph.D. Isala Klinieken, Zwolle (P. L. P. Brand, M.D. Ph.D., Ph.D., A. W. A. Kamps, M.D., Ph.D.). Medical Center, Alkmaar (G. Brinkhorst, M.D.). VU Medical Center, Amsterdam (J. E. Dankert-Roelse, M.D. Ph.D., A. F. Nagelkerke M.D.). Maxima Medical Center, Veldhoven (R. van Gent, M.D., Ph.D.). Maasland Hospital, Sittard (J. W. C. M. Heijnens, M.D.). University Hospital Maastricht (J. J. E. Hendriks, M.D., Ph.D., Q. Jöbsis, M.D., Ph.D.). University Medical Center/Wilhelmina Children’s Hospital, Utrecht (J. van der Laag, M.D., H. J. L. Brackel, M.D., Ph.D.). Academic Medical Center, Amsterdam (J. C. van Nierop, M.D.). Amphia Hospital, Breda (A. A. P. H. Vaessen-Verberne, M.D., Ph.D.) all from The Netherlands.

Lung hyperinflation, perception of bronchoconstriction and airway hyperresponsiveness

To compare the influence of underlying airway inflammation and lung hyperinflation on dyspnea during induced bronchoconstriction in subjects with mild asthma (or asymptomatic airway hyperresponsiveness (AAHR). Fourteen mild asthmatic and 14 AAHR subjects had methacholine and 5'-adenosine monophosphate (AMP) challenges, and induced sputum analysis. Changes in inspiratory capacity (IC) and respiratory symptom scores were measured after challenges. Perception of respiratory symptoms was recorded on a modified Borg scale. The mean baseline FEV1, IC, mean provocative concentration of methacholine inducing a 20% decrease in FEV1 (PC20), the mean PC20 AMP and median inflammatory cell counts were similar in both groups. After methacholine, mean (+/-SD) reductions in FEV1 were 24.7+/-10.3% in mild asthma and 35.6+/-19.1% in AAHR (P>0.05); reductions in IC were, respectively, 10+/-12% and 24+/-20% (P>0.05); mean breathlessness scores at PC20 were 1.1 in mild asthma and 0 in AAHR P=0.003), and mean chest tightness scores were 1.2 in mild asthma and 0.8 in AAHR (P>0.05). Maximum chest tightness scores following MC correlated with the maximum decrease in IC in mild asthma (rs=0.75,P=0.009) and with the maximum decrease in FEV1 in AAHR (rs=0.60,P=0.04). After AMP, symptom scores were not significantly correlated with decreases in FEV1 or IC. The number of inflammatory cells was not correlated with decreases in IC after methacholine, AMP or with their PC20s, although inflammation was minimal in both groups. Lower breathlessness scores in AAHR compared to mild asthma were not explained by differences in lung hyperinflation nor in airway inflammation.

Differentiation between the sensory and affective aspects of histamine-induced bronchoconstriction in asthma

Respiratory symptom perception research has focused mainly on respiratory sensations. Because dyspnea is multidimensional, affective aspects should be investigated. Patients with asthma (N=25) underwent a histamine provocation until a 20% fall in forced expiratory volume in 1s (FEV(1)). After each dose level, 6 symptoms of dyspnea intensity and 6 symptoms of dyspnea affectivity were rated. Individual perceptual sensitivity was determined by calculating the linear slope between the fall in FEV(1) and the increase in the total symptom score, and for affective and sensory symptoms separately [Bijl-Hofland, Folgering, van den Hoogen, et al. Perception of bronchoconstriction in asthma patients measured during histamine challenge test. Eur Respir J 1999;14:1049-54]. Trait anxiety, baseline state anxiety, daily asthma symptoms and catastrophizing during an asthma exacerbation were also assessed. Sensitivity was unrelated to physiological indices of disease severity (i.e., baseline FEV(1) and histamine dose level at 20% fall in FEV(1)), whereas it was positively related to trait anxiety, state anxiety, daily asthma symptoms and catastrophic thinking during an asthma exacerbation in daily life. These relationships were overall much stronger for affective than for sensory symptom slopes. In stepwise multiple regressions, state anxiety was the best predictor of the affective symptom slopes, whereas catastrophic thinking during an asthma exacerbation was the best predictor for the sensory symptom slopes. The differentiation between sensory and affective components of dyspnea adds to the understanding of respiratory symptom perception in asthma.

Smoking and Asthma: Clinical and Radiologic Features, Lung Function, and Airway Inflammation

Smoking may influence the type of airway inflammation observed in asthma and its response to therapy. More studies are needed on how smoking-induced changes in lung function/structure and airway inflammation may result in a change in clinical expression. We compared clinical, physiologic, radiologic, and airway inflammatory features of 22 smoking asthma patients (cigarette smoking history, 14.0 ± 7.6 pack-years [mean ± SD]) and 27 nonsmoking asthma patients. Mean age/duration of asthma of smoking and nonsmoking asthma patients were 31 years/14 years and 29 years/17 years, respectively. Quality of life, FEV1, bronchodilator response, perception of bronchoconstriction, and methacholine responsiveness were similar in the two groups. Compared to nonsmoking asthma patients, smokers had more respiratory symptoms, a lower mean forced expiratory flow at 25 to 75% of FVC, FEV1/FVC ratio, and lung diffusion capacity, and a higher functional residual capacity. Induced-sputum neutrophil and bronchial cell counts were higher and exhaled breath condensate pH was more acidic in smoking asthma patients. On high-resolution CT, airway and parenchymal abnormalities were more common in smoking asthma patients than in nonsmokers. In conclusion, compared with nonsmoking asthma patients, smoking asthma patients have features similar to what could be found in early stages of COPD. Smoking may influence the type of airway inflammation observed in asthma and its response to therapy. More studies are needed on how smoking-induced changes in lung function/structure and airway inflammation may result in a change in clinical expression. We compared clinical, physiologic, radiologic, and airway inflammatory features of 22 smoking asthma patients (cigarette smoking history, 14.0 ± 7.6 pack-years [mean ± SD]) and 27 nonsmoking asthma patients. Mean age/duration of asthma of smoking and nonsmoking asthma patients were 31 years/14 years and 29 years/17 years, respectively. Quality of life, FEV1, bronchodilator response, perception of bronchoconstriction, and methacholine responsiveness were similar in the two groups. Compared to nonsmoking asthma patients, smokers had more respiratory symptoms, a lower mean forced expiratory flow at 25 to 75% of FVC, FEV1/FVC ratio, and lung diffusion capacity, and a higher functional residual capacity. Induced-sputum neutrophil and bronchial cell counts were higher and exhaled breath condensate pH was more acidic in smoking asthma patients. On high-resolution CT, airway and parenchymal abnormalities were more common in smoking asthma patients than in nonsmokers. In conclusion, compared with nonsmoking asthma patients, smoking asthma patients have features similar to what could be found in early stages of COPD.

Clinical features and airway inflammation in mild asthma versus asymptomatic airway hyperresponsiveness

We still do not know why some subjects with airway hyperresponsiveness (AHR) experience no respiratory symptoms. Our aim was to compare pulmonary function, perception of bronchoconstriction, and airway inflammation in atopic subjects with mild recently diagnosed (<5 years, n=30) or longer-standing (5 years or more, n=30) symptomatic asthma in comparison with atopic subjects with asymptomatic AHR (n=27). All subjects had measurements of expiratory flows, PC(20) methacholine, perception of breathlessness and induced sputum cell differential, eosinophil cationic protein and alpha(2)-macroglobulin levels. Compared with the other groups, PC(20) was significantly lower in longer-standing asthma and perception score for breathlessness at 20% fall in FEV(1) was lower in asymptomatic subjects. Markers of airway inflammation were similar in all groups. There were no significant correlations between sputum eosinophils, alpha(2)-macroglobulin and/or eosinophil cationic protein levels and FEV(1), FVC or PC(20) in either group. Subjects with mild asthma or asymptomatic AHR are similar in regard to induced sputum markers of airway inflammation. Although perception of bronchoconstriction was slightly lower in asymptomatic subjects, additional factors are probably involved to explain why they report no respiratory symptoms. Further studies are needed to determine why these last are asymptomatic.

Perception of bronchoconstriction in obstructive pulmonary diseases (disease-specific dyspnoea).

The perception of dyspnoea differs between subjects with obstructive pulmonary diseases, partly because the underlying mechanisms for bronchoconstriction are different. We investigated the perception of bronchoconstriction in subjects with bronchiectasis, asthma and chronic bronchitis and possible contributing factors. Forty-seven non-smoking subjects with bronchiectasis, 50 subjects with asthma and 31 with chronic bronchitis were challenged with histamine. The Borg score was assessed before and after each challenge. The perception score corresponding to a fall in the forced expiratory volume in 1 s (FEV(1)) by 20% (PS(20)) was calculated. The mean values of DeltaBorg/DeltaFEV(1) (the Borg score change divided by the change in FEV(1) as a percentage of the baseline FEV(1)) and PS(20) of subjects with bronchiectasis and chronic bronchitis were significantly lower than in subjects with asthma after histamine challenge. The ratio of non-perceivers was higher in bronchiectasis (25.5%) and in chronic bronchitis (32.3%) than in asthma (4.0%). When all subjects were considered, DeltaBorg/DeltaFEV(1) values were significantly related to female sex ( r (2)=11.5%, P =0.0001), but not to age, duration of the disease, PD(20) or baseline FEV(1)%. The present study indicates that perception of histamine-induced bronchoconstriction is lower in patients with bronchiectasis and chronic bronchitis than in asthmatic patients, and that sex partially contributes to this difference.

Measures of Perception of Bronchoconstriction and Clinical and Functional Data Are Not Interrelated in Asthma

Background: Sensitivity and absolute perceptual magnitude characterize the perception of bronchoconstriction (PB). Objectives: To define whether clinical and functional characteristics and level of bronchial hyperresponsiveness (BHR) correlate with these two PB indexes during bronchial challenge in asthma. Methods: PB on both the Borg scale and the visual-analogue scale (VAS) was assessed in 45 consecutive asthmatics during a methacholine-induced decrease in forced expiratory volume in 1 s (FEV₁) and specifically quantified as Borg and VAS slope, as a measure of sensitivity, whereas scores at a 20% FEV₁ decrease (PB₂₀) were assessed as a measure of absolute perceptual magnitude. Clinical score and BHR were also assessed. Results: PB₂₀ related to slope on both the Borg scale and the VAS (p < 0.0001). PB₂₀ and slope related neither to clinical score nor to baseline functional data on both scales. The relationship between the level of BHR and PB₂₀ on either scale was of questionable clinical significance (r² = 7%). Conclusions: Irrespective of the scale employed, our data indicate the need for directly assessing PB rather than deriving it from clinical and functional data and level of BHR.

Apparent but not real increase in asthma prevalence during the 1990s.

The authors investigated changes in asthma prevalence and perception of bronchoconstriction over 6 yrs in adults of Newcastle-upon-Tyne. Postal questionnaires were sent to 6,000 subjects aged 20-44 yrs in 1992-1993 and 1998-1999. Random samples of 600 responders had assessments of atopy, airway responsiveness, and their ability to perceive methacholine-induced bronchoconstriction. The prevalences of asthmatic symptoms, physician-diagnosis, and medication use increased by an average of 4.4%, particularly in subjects aged <30 yrs (8.7 versus 2.7). Atopy prevalence increased from 25% to 31% but atopics and nonatopics had similar mean changes in questionnaire data (5.2 versus 3.4). The probability of a positive methacholine test decreased as did the mean methacholine dose/response slope (0.00527 to 0.00379), indicating lower levels of airway responsiveness. This can be largely explained by an increase in use of inhaled corticosteroids (5.0-9.3%). The proportion of subjects perceiving bronchoconstriction during methacholine tests increased from 63 to 77%. The authors conclude that current changes in asthma epidemiology in adults may result from increased awareness of symptoms (and/or an increased willingness to report them), and from an increased willingness of physicians to make the diagnosis and prescribe treatment, not from increased disease prevalence.

Effect of Budesonide on the Perception of Induced Airway Narrowing in Subjects with Asthma

The perception of bronchoconstriction may be modulated by airway inflammation. However, the effect of inhaled corticosteroid (ICS) treatment on perception in subjects with asthma has received limited study. The aim of this study was to determine the effect of inhaled budesonide on the perception of breathlessness induced by histamine challenge. Thirty-five subjects with poorly controlled asthma were randomized to receive budesonide (1,600 or 3,200 microg/d) for 8 wk, followed by 8 wk at 1,600 microg/d and subsequent downtitration according to a clinical algorithm. Borg scores were recorded during histamine challenges performed at baseline and at 8, 16, 24, 48, and 72 wk. Perception was estimated as the slope of Borg/% fall FEV(1). The Borg/FEV(1) slope increased significantly after 8 wk of budesonide (0.09 [0.08-0.12] to 0.15 [0.11-0.19], p = 0.002), and remained increased compared with baseline values at all subsequent visits. There were no significant differences in Borg/ FEV(1) slope between subjects who were and were not taking ICS at study entry. The magnitude of change in the Borg/FEV(1) slope did not differ significantly between treatment groups and was not related to changes in baseline FEV(1), airway hyperresponsiveness, blood eosinophils, or serum eosinophil cationic protein (ECP). We conclude that treatment with budesonide enhances the perception of airway narrowing, but the effect is unrelated to budesonide dose, or to changes in circulating eosinophil markers.

Perception of bronchoconstriction in smokers with airflow limitation

To our knowledge, no data have been provided as to whether and to what extent dynamic hyperinflation, through its deleterious effect on inspiratory muscle function, affects the perception of dyspnoea during induced bronchoconstriction in patients with chronic airflow obstruction. We hypothesized that dynamic hyperinflation accounts in part for the variability in dyspnoea during acute bronchoconstriction. We therefore studied 39 consecutive clinically stable patients whose pulmonary function data were as follows (% of predicted value): vital capacity (VC), 97.8% (S.D. 16.0%); functional residual capacity, 105.0% (18.8%); actual forced expiratory volume in 1s (FEV1)/VC ratio, 56.1% (6.3%). Perception of dyspnoea using the Borg scale was assessed during a methacholine-induced fall in FEV1. The clinical score and the treatment score, the level of bronchial hyper-responsiveness and the cytological sputum differential count were also assessed. In each patient, the percentage fall in FEV1 and the concurrent Borg rating were linearly related, with the mean slope (PD slope) being 0.09 (0.06). The percentage fall in FEV1 accounted for between 41% and 94% of the variation in the Borg score. At a 20% fall in FEV1, the decrease in inspiratory capacity (ΔIC) was 0.156 (0.050) litres. Patients were divided into three subgroups according to the PD slope (arbitrary units/% fall in FEV1): subgroup I [eight hypoperceivers; PD slope 0.026 (0.005)], subgroup II [26 moderate perceivers; 0.090 (0.037)] and subgroup III [five hyperperceivers; 0.200 (0.044)]. By applying stepwise multiple regression analysis with the PD slope as the dependent variable, and other characteristics (demographic, clinical and functional characteristics, smoking history, level of bronchial hyper-responsiveness and sputum cytological profile) as independent variables, ΔIC (r2 = 45%, P &lt; 0.00001) and to a lesser extent treatment score (r2 = 17.3%, P &lt; 0.0006), and to an even lesser extent age (r2 = 3%, P &lt; 0.05), independently predicted a substantial amount (r2 = 65.27%, P &lt; 0.00001) of the variability in the Borg slope. Thus acute hyperinflation, and to a lesser extent treatment score and age, account in part for the variability in the perception of dyspnoea after accounting for changes in FEV1 during bronchoconstriction in patients with chronic airflow obstruction.

Perception of bronchoconstriction in smokers with airflow limitation

To our knowledge, no data have been provided as to whether and to what extent dynamic hyperinflation, through its deleterious effect on inspiratory muscle function, affects the perception of dyspnoea during induced bronchoconstriction in patients with chronic airflow obstruction. We hypothesized that dynamic hyperinflation accounts in part for the variability in dyspnoea during acute bronchoconstriction. We therefore studied 39 consecutive clinically stable patients whose pulmonary function data were as follows (% of predicted value): vital capacity (VC), 97.8% (S.D. 16.0%); functional residual capacity, 105.0% (18.8%); actual forced expiratory volume in 1 s (FEV(1))/VC ratio, 56.1% (6.3%). Perception of dyspnoea using the Borg scale was assessed during a methacholine-induced fall in FEV(1). The clinical score and the treatment score, the level of bronchial hyper-responsiveness and the cytological sputum differential count were also assessed. In each patient, the percentage fall in FEV(1) and the concurrent Borg rating were linearly related, with the mean slope (PD slope) being 0.09 (0.06). The percentage fall in FEV(1) accounted for between 41% and 94% of the variation in the Borg score. At a 20% fall in FEV(1), the decrease in inspiratory capacity (Delta IC) was 0.156 (0.050) litres. Patients were divided into three subgroups according to the PD slope (arbitrary units/% fall in FEV(1)): subgroup I [eight hypoperceivers; PD slope 0.026 (0.005)], subgroup II [26 moderate perceivers; 0.090 (0.037)] and subgroup III [five hyperperceivers; 0.200 (0.044)]. By applying stepwise multiple regression analysis with the PD slope as the dependent variable, and other characteristics (demographic, clinical and functional characteristics, smoking history, level of bronchial hyper-responsiveness and sputum cytological profile) as independent variables, Delta IC (r(2)=45%, P<0.00001) and to a lesser extent treatment score (r(2)=17.3%, P<0.0006), and to an even lesser extent age (r(2)=3%, P<0.05), independently predicted a substantial amount (r(2)=65.27%, P<0.00001) of the variability in the Borg slope. Thus acute hyperinflation, and to a lesser extent treatment score and age, account in part for the variability in the perception of dyspnoea after accounting for changes in FEV(1) during bronchoconstriction in patients with chronic airflow obstruction.

Perception of bronchoconstriction and bronchial hyper-responsiveness in asthma

Perception of bronchoconstriction and bronchial hyper-responsiveness in asthma

Perception of bronchoconstriction and bronchial hyper-responsiveness in asthma

The inter-relationship between the perception of bronchoconstriction, bronchial hyper-responsiveness and temporal adaptation in asthma is still a matter of debate. In a total of 52 stable asthmatic patients, 32 without airway obstruction ¿forced expiratory volume in 1 s (FEV(1))/vital capacity (VC) 84.1% (S.D. 7.9%), and 20 with airway obstruction [FEV(1)/VC 60% (4%)], we assessed the perception of bronchoconstriction during methacholine inhalation by using: (i) the slope and intercept of the Borg and VAS (Visual Analog Scale) scores against the decrease in FEV(1), expressed as a percentage of the predicted value; and (ii) the Borg and VAS scores at a 20% decrease in FEV(1) from the lowest post-saline level (PB(20)). Bronchial hyper-responsiveness was assessed as the provocative concentration of methacholine causing a 20% fall in FEV(1) (PC(20)FEV(1)). The reduction in FEV(1) was significantly related to the Borg and VAS scores, with values for the group mean slope and intercept of this relationship of 0.13 (S.D. 0.08) and -1.1 (3.02) for Borg, and 1.5 (1.19) and -12.01 (35) for VAS. PB(20) was 3 (1.75) with Borg scores and 34.6 (20.5) with VAS scores. Compared with the subgroup without airway obstruction, the obstructed subgroup exhibited similar slopes, but lower Borg and VAS intercepts. For similar decreases in FEV(1) (5-20% decreases from the lowest post-saline values), the Borg and VAS scores were lower in the non-obstructed than in the obstructed subgroup. PC(20)FEV(1) was significantly related to both Borg PB(20) and VAS PB(20) when considering all patients. When assessing the subgroups, PC(20)FEV(1) was related to Borg PB(20) and VAS PB(20) in the non-obstructed subjects, but not in the obstructed subjects. In neither subgroup was the log of the cumulative dose related to the Borg and VAS scores at the end of the test. We conclude that, unlike in previous studies, the ability to perceive acute bronchoconstriction may be reduced as background airflow obstruction increases in asthma. Bronchial hyper-responsiveness did not play a major role in perceived breathlessness in patients without airway obstruction, and even less of a role in patients with obstruction. The cumulative dose of agonist did not appear to influence the perception of bronchoconstriction.

Relation of the perception of airway obstruction to the severity of asthma

BACKGROUNDPatients with a poor perception of their symptoms of asthma seem to have an increased risk of an asthma attack. The influence of factors such as airway calibre, bronchial hyperresponsiveness,...

Improving outcomes in elderly patients with asthma.

Although often regarded as a disease of childhood, asthma is common in elderly people. Although recent figures show a decline over the past few years in the number of asthma deaths in children and younger adults, the same is not true of older adults, in whom most asthma deaths occur. Differences between asthma in young and old patients are seen not only in response to treatment. The nonspecific presentation of asthma in elderly adults means that the diagnosis of asthma is difficult to make. In addition, research suggests that physicians are reluctant to use spirometry and measurement of reversibility when investigating respiratory symptoms in old people. This leads to a tendency to label breathless or wheezy elderly patients as having chronic obstructive pulmonary disease (COPD) rather than asthma. In turn, patients with a diagnosis of COPD are less likely to be treated with bronchodilators and corticosteroids. Treatment guidelines for the management of asthma in children and younger adults may need to be adapted when applied to older patients. Reduced perception of bronchoconstriction may lead to underuse of bronchodilators prescribed 'as required'. The bronchodilator response to beta2-agonists is attenuated as part of the normal aging process, and other groups of bronchodilator medications should be considered. Inhaler technique can be a particular problem in elderly patients with asthma, requiring careful choice of inhaler device. However, the frequent presence of multiple pathology and multiple medication in this age group enhances the risk of adverse effects from oral preparations, and so the inhaled route should be preferred wherever possible. Underestimation of the severity of an acute exacerbation of asthma by both patient and doctor has been suggested as a contributory factor to poor outcome in older people. Since the cardiovascular responses to hypoxia and bronchoconstriction tend to diminish with increasing age, objective measures of asthma severity (peak flow monitoring and blood gas estimation) are essential in this age group.

Perception of respiratory symptoms after methacholine-induced bronchoconstriction in a general population.

In an epidemiological study, methacholine-induced bronchoconstriction was used as a physical illustration of the sensations associated with asthma. The objective of this study was to assess whether familiarity with these sensations could be used as a measure of asthma prevalence. Eight hundred and seventy six subjects aged 20-44 yrs completed a respiratory questionnaire and a measurement of airway responsiveness (the provocative dose of methacholine causing a 20% fall in forced expiratory volume in one second (PD20)). Subjects were asked about their perception of, familiarity with and description of the respiratory sensations experienced at the time of maximal bronchoconstriction. The questionnaire-derived lifetime prevalences of wheeze, chest tightness and undue breathlessness were 43, 35 and 22% respectively. Asthma medication was used by 8% and the lifetime prevalence of diagnosed asthma was 12%. Quantifiable levels of airway responsiveness were measured in 34%, and airway responsiveness in the range considered to be consistent with untreated active asthma was present in 21%. Bronchoconstriction was perceived by 59%. Perception of bronchoconstriction was associated with the magnitude of bronchoconstriction, younger age, female sex and questionnaire-reported symptoms. Of subjects able to perceive bronchoconstriction, 58% reported previous experience of (familiarity with) the associated respiratory sensations. Familiarity with the sensations of bronchoconstriction was associated with questionnaire-reported symptoms, diagnosed asthma and increasing levels of airway responsiveness. There was poor agreement between the respiratory symptoms reported by questionnaire before the methacholine test and the words used to describe respiratory sensations induced by the test. Familiarity with the sensations of methacholine-induced bronchoconstriction has all the appropriate associations of a measure of asthma prevalence and may be a useful adjunct to symptom questionnaires and airway responsiveness measurements in epidemiological studies. A sizeable number of subjects can be identified with intermediate levels of airway responsiveness, who are able to perceive bronchoconstriction and are familiar with the sensations associated with it, yet who are not recognized to suffer from asthma.

Characteristics of subjects with a high frequency of emergency visits for asthma

The determinants of frequent visits to the emergency department (ED) for asthma were evaluated in 30 patients who made 2 or more ED visits for asthma (mean, 3.1; range, 2 to 9) over a period of 1 year. They were matched for age, sex, and medication with a control group of asthmatic patients who had made no ED visits within the same period. Evaluation included measurements of expiratory flows (baseline FEV 1; PEFR 4 times daily for 3 weeks), airway responsiveness to methacholine, perception of induced bronchoconstriction, and questionnaires on quality of life and knowledge of asthma and its management. In comparison with the control group, the study group showed a trend toward inferior socioeconomic status, education level, and technical abilities (eg, inhaler use). Both groups had similar baseline FEV 1, reversibility of airflow obstruction, methacholine-induced changes in expiratory flows, and perception of bronchoconstriction. Diurnal variation in PEFR was slightly increased in the study group. Absenteeism from work or school was higher in the study group but quality of life score was similar to controls. Patients with frequent ED visits showed significantly lesser knowledge of asthma control criteria, as well as an overall trend toward reduced asthma management knowledge and skills. In conclusion, in addition to the previously reported undertreatment of asthma, other factors such as insufficient asthma management knowledge and skills may contribute to frequent ED visits for asthma.

Respiratory sensation during bronchial challenge testing with methacholine, sodium metabisulphite, and adenosine monophosphate.

There is some evidence that the perception of bronchoconstriction may very according to the nature of the provoking stimulus. The aims of this study were, firstly, to develop a method for measuring dyspnoea during induced bronchoconstriction in patients with asthma and, secondly, to apply this method to testing differences between directly and indirectly acting bronchoconstricting stimuli. Descriptive terms suitable for quantifying respiratory discomfort due to bronchoconstriction in patients with asthma were identified in a preliminary investigation. The relation between reduction in forced expiratory volume in one second (FEV1) and respiratory discomfort, measured using a visual analogue scale (VAS), was then studied during challenges with three different inhaled stimuli: methacholine (MCH), sodium metabisulphite (MBS), and adenosine monophosphate (AMP). Three indices were calculated to describe the relation: the VAS value associated with a 20% fall in FEV1 (FEV20 VAS); the ratio of the final VAS value to the final percentage fall in FEV1 (VAS-FEV1 ratio); and the regression coefficient for predicting VAS from the percentage fall in FEV1 within each challenge (beta VAS FEV1). "Difficulty in breathing" and "chest tightness" were selected as suitable terms for quantifying respiratory discomfort. There were no differences between the three agonists in the qualitative aspects of the respiratory sensation. In paired challenges with the same agonist the three indices were all found to be reproducible for both sensations measured. MCH induced less intense difficulty in breathing and chest tightness for a given fall in FEV1 than did AMP. There was a trend in the same direction for the comparison between MCH and MBS. There were no differences between AMP and MBS. FEV20 VAS was less powerful in discriminating between agonists than the two slope indices. The relation between induced reduction in FEV1 and the intensity of respiratory discomfort can be measured reliably. The indirectly acting bronchoconstricting agonists AMP and MBS induced more intense respiratory discomfort for a given fall in FEV1 than the direct agonist MCH. This may be due to differences in unmeasured mechanical changes in the lungs or to an additional action on airway sensory nerves.

Persistence of Airway Obstruction and Hyperresponsiveness in Subjects With Asthma Remission

This study was designed to determine if there is residual airflow obstruction and/or airway hyperresponsiveness in adults with symptomatic asthma remission, and if age at remission or its duration influence these parameters. We studied 30 subjects, (20 men, 10 women, 28 atopics, aged 18 to 61 years; mean, 32 years) with a history of asthma (mean duration, 2 to 33 years) but who reported no symptoms or medication requirement for > or 2 years. They were individually matched for age, sex, and atopy, to a control group of 30 subjects without history of asthma. Each subject had a respiratory questionnaire and measurements of expiratory flows, lung volumes, and bronchodilator response. Morning/evening peak expiratory flow rates (PEFRs) were recorded for a 2-week period and two methacholine inhalation tests were obtained on separate days. Initial FEV1 and FVC for ex-asthmatics (controls) were, respectively, 91.0 +/- 2.5 percent and 97.8 +/- 2.3 percent (104.1 +/- 1.9 and 104.0 +/- 1.8 percent) of predicted values. Twenty nine ex-asthmatics (15 controls) had occasional respiratory symptoms, not attributed to asthma. Most subjects with asthma remission had evidences of mild airflow obstruction, associated to a methacholine response either increased in 11 (PC20 methacholine, 0.18 to 5.6 mg/ml) or "borderline" in 10 others (PC20 between 8 and 20 mg/ml). Airway responsiveness was normal (PC20 > 20 mg/ml) in 8 ex-asthmatics and in 21 controls (PC20 was under 8 mg/ml and between 10 and 20 mg/ml in, respectively, 5 and 4 controls). Mean reversibility of FEV1 after 200 micrograms of albuterol was 5.7 (range, -1.1 to 14.1 percent) compared with 2.5 (-4.4 to 10.5) in controls. Mean and maximal diurnal variation of PEFR were, respectively, 4.6 +/- 0.4 percent and 12.3 +/- 1.3 percent (controls, 2.9 +/- 0.3 and 7.0 +/- 0.8 percent). There was a significant correlation between PC20 and age at the diagnosis of asthma or at the onset of remission. Airway responsiveness was significantly less when asthma or remission of asthma occurred at a younger age, although there was no difference for baseline FEV1 and no significant correlation between PC20 and duration of asthma or of remission. Perception of bronchoconstriction was similar in both controls and ex-asthmatics. In conclusion, most ex-asthmatics who considered to be in asthma remission showed a persistent increase in airway responsiveness with or without mild airflow obstruction, suggesting that symptom report may be insufficient to determine that asthma is in true remission.