The Use of Oscillometry as a Measure of Airway Responsiveness in Asthmatic Children After Histamine and Methacholine Bronchoprovocation with Dosimeter-MedicAid and DeVilbiss Nebulizers

To explore the use of oscillometry as a measure of airway responsiveness, 69 asthmatic children underwent histamine and methacholine bronchoprovocation using dosimeter-MedicAid (Jaeger Co.; Germany) and DeVilbiss nebulizers (DeVilbiss, Bornemouth; England). The mean increase in R5 resistance in challenge testing measured after methacholine with the dosimeter-MedicAid nebulizer was 77.14% compared with 65.05% using histamine. Using the dosimeter-DeVilbiss nebulizer, the mean increases in R5 resistance following methacholine and histamine testing were 57.50% and 59.36%, respectively. The resistance R5 over R20 significantly correlated with forced expiratory volume in 1 second (FEV₁). The MedicAid produced a more aggressive challenge than the DeVilbliss nebulizer. Oscillometry can be used to monitor the level of airway hyperresponsiveness following bronchoprovocation tests.     

Increased bronchial responsiveness to histamine associated with shortened inhalation time

A study was undertaken to assess the variability of results of histamine inhalation tests with the tidal breathing method, keeping the total dose of histamine delivered to the mouth constant but using either different nebulizers or the same Wright nebulizer operated under changing conditions. Seventeen asthmatic children had double histamine bronchial provocation tests with a Bennett-Twin nebulizer (output 0.31 ml/min, nebulization time 1 min) and a Wright nebulizer (output 0.15 ml/min, nebulization time 2 min), with a driving flow rate, in both instances, of 7 L/min. Another group of 15 asthmatic children had double provocation tests with a Wright nebulizer driven by a flow rate of either 7 L/min (output 0.15 ml/min, nebulization time 2 min) or 12 L/min (output 0.30 ml/min, nebulization time 1 min). In each experiment the volume of histamine solution delivered was about 0.30 ml. PC20-FEV1 was significantly lower, indicating an increased bronchial response, when both methods using "faster" delivery of histamine were used. We conclude that comparison of results obtained with histamine inhalation tests by the tidal breathing method cannot be made unless the nebulizer and operating criteria are the same.     

Hyperosmolarity-induced increases in airway responsiveness and late asthmatic responses

Airway responsiveness to inhaled methacholine was assessed before and after bronchial challenge with ultrasonically nebulized hyperosmolar saline (UNHS), and these changes were correlated with the development of late asthmatic responses (LAR). Sixteen subjects with mild to moderate asthma had two consecutive methacholine challenges before and one after a cumulative-dose challenge with UNHS. Twelve of these subjects also had a single-dose hyperosmolar challenge to document the occurrence of LAR and determine if UNHS had a significant cumulative-dose effect. If a LAR was observed, a control day without challenge completed the study. Responsiveness to methacholine was similar on the 2 baseline methacholine challenges with a provocative concentration producing a 20% fall in forced expiratory volume in one second (PC20) (mean +/- SEM) of 1.11 +/- 0.94 and 1.16 +/- 0.94 mg.ml.1 (r: 0.98). However, it was significantly increased after the inhalation of UNHS with a PC20 (mean +/- SEM) of 0.57 +/- 1.00 mg.ml.1 (p less than 0.001). Two subjects developed a late fall in forced expiratory volume in one second (FEV1) of 19 and 46% after hyperosmolar challenge. In this last subject, the LAR, not reproduced on the control day, was associated with a marked post-UNHS change in PC20, going from a baseline of 4.4 to 0.7 mg.ml.1 after UNHS. The % fall in FEV1 following the dose-response hyperosmolar challenge and the single-dose hyperosmolar challenge were not different, with mean values +/- SEM of 34.9 +/- 2.2 and 35.8 +/- 4.1, respectively, (p greater than 0.5). In conclusion, airway responsiveness to methacholine may increase following hyperosmolar saline inhalation, often unrelated to LAR.     

Determinants of airway responsiveness to adenosine 5'-monophosphate in school-age children with asthma

Airway responsiveness to adenosine 5'-monophosphate (AMP) is more specific than that to direct stimuli for asthma diagnosis and response to treatment, but is not detected in all patients with asthma. This study was planned to determine predictive factors for responsiveness to AMP in asthmatic children between 7-16 years old. We performed a retrospective analysis of data from 71 asthmatic children who were challenged by AMP in our department. All children were characterized by skin-prick and lung function tests and bronchial challenge with AMP. Data on simultaneous methacholine challenge tests were available for 46 children, 34 of whom were also challenged with a third stimulus, exercise. Potential demographic factors for responsiveness to AMP were assessed by logistic regression analysis within the study group. The proportion of school-age children with asthma responsive to AMP was 39.4%. The geometric mean provocative concentration of AMP causing a 20% decrease in forced expiratory volume in 1 sec (PC20AMP) was 20.50 mg/ml (range, 0.31-377 mg/ml). There were no significant differences either in response to methacholine below 16 mg/ml (P = 0.66) or in PC20 methacholine level (P = 0.075) when we compared AMP-responsive and -nonresponsive children. These two groups also did not differ with respect to their response to exercise challenge in subgroup analysis (P = 0.34). Among school-age children with asthma, allergic rhinitis (P = 0.004) and sensitizaton to grass mix (P = 0.001), cereal mix (P = 0.003), house dust mite (P = 0.024), and cat (P = 0.043) were found to be more frequent in AMP-responsive children than the others. There was no difference in lung function test parameters between children responsive to AMP and the others. Grass pollen sensitization was found to be the only independent predictive factor for determining AMP responsiveness in school-age children with asthma (odds ratio, 5.65; 95% confidence interval, 1.84-17.45; P = 0.003). In conclusion, atopic sensitization is the most important predictive factor for responsiveness to AMP in school-age children with asthma, as in adults.     

Inhaled mannitol identifies methacholine-responsive children with active asthma

Inhaled mannitol has been developed for bronchial challenge testing in adults. This study determined if mannitol could identify children with active asthma and responsive to methacholine, and whether mannitol challenge was faster to complete than methacholine challenge. Twenty-five children (aged 6-13 years) responsive to methacholine and 10 nonasthmatic children unresponsive to methacholine were studied. The methacholine challenge (Cockcroft protocol) was followed by a mannitol challenge on separate days. Twenty-one asthmatic children were positive to mannitol. Three taking inhaled corticosteroids with borderline methacholine responsiveness did not respond to mannitol, and one could not complete the mannitol challenge due to cough. The geometric mean (GM) and 95% confidence interval (CI) for PD(15) for mannitol was 39 mg (19, 78), and PC(20) for methacholine was 0.6 mg/mL (0.35-1.02) (r(p) = 0.75, p < 0.001, n = 21). Responses to mannitol were repeatable: GM PD(15) for the first challenge was 29 mg (CI: 17,50), and for the second challenge, 33 mg (CI: 20, 55) (P = 0.44, n = 9). Mannitol was faster to administer than methacholine (median (range)) 14 min (5-32) vs. 29 min (19-49), respectively (P < 0.001). Time to recover to baseline FEV(1) spontaneously and after bronchodilator administration was similar for both challenges. There were no significant falls in arterial oxygen saturations. During mannitol challenge, the mean (SD) fall in FEV(1) in nonasthmatic children was 3.1% (2.9). We conclude that mannitol identifies children with airway hyperresponsiveness and is faster to perform than the methacholine challenge.     

Validation of a single concentration methacholine inhalation provocation test (SCIPT) in children.

A new method to assess bronchial hyperresponsiveness (BHR) using a single concentration methacholine has already been validated in adults with asthma. Because the geometrical dimensions of the airways in children are different, the results from studies in adults cannot be extrapolated to children. In this study, we validated the single concentration methacholine inhalation provocation test (SCIPT) in children. Twenty-two children performed three methacholine inhalation challenge tests in random order. Two challenges were performed according to the SCIPT: doubling doses (0.03-1.8 mg; maximal cumulated dose 3.6 mg) were administered with an Aerosol Provocation System (Masterscope, Jaeger). The third challenge was performed according to a standard dosimeter method (SDM): doubling doses (0.002-1.8 mg; maximal cumulative dose 3.5 mg) were administered with a DeVillbiss 646 nebulizer. The degree of BHR is expressed as a PD20. A difference of < 1.5 dose step was assumed to be due to intraindividual variation. We found an intraclass correlation of 0.91 between both tests according to the SCIPT and of 0.80 between the SCIPT and SDM. We found, according to the method of Bland and Altman, good agreement when comparing these two challenge tests. The single concentration inhalation provocation test is reproducible and shows good agreement with a standard dosimeter method to test bronchial responsiveness in children.     

Validation of a Single Concentration Methacholine Inhalation Provocation Test (SCIPT) in Children

A new method to assess bronchial hyperresponsiveness (BHR) using a single concentration methacholine has already been validated in adults with asthma. Because the geometrical dimensions of the airways in children are different, the results from studies in adults cannot be extrapolated to children. In this study, we validated the single concentration methacholine inhalation provocation test (SCIPT) in children. Twenty-two children performed three methacholine inhalation challenge tests in random order. Two challenges were performed according to the SCIPT: doubling doses (0.03–1.8 mg; maximal cumulated dose 3.6 mg) were administered with an Aerosol Provocation System (Masterscope, Jaeger). The third challenge was performed according to a standard dosimeter method (SDM): doubling doses (0.002–1.8 mg; maximal cumulative dose 3.5 mg) were administered with a DeVillbiss 646 nebulizer. The degree of BHR is expressed as a PD₂₀. A difference of < 1.5 dose step was assumed to be due to intraindividual variation. We found an intraclass correlation of 0.91 between both tests according to the SCIPT and of 0.80 between the SCIPT and SDM. We found, according to the method of Bland and Altman, good agreement when comparing these two challenge tests. The single concentration inhalation provocation test is reproducible and shows good agreement with a standard dosimeter method to test bronchial responsiveness in children.     

Maximal Airway Narrowing on the Dose-Response Curve to Methacholine Is Increased After Exercise-Induced Bronchoconstriction

The changes in airway responsiveness between before and after exercise in asthma are not well defined. We investigated the effect of exercise on PC20 (bronchial sensitivity) and maximal airway narrowing (MAN) on the dose-response curve to methacholine in 56 mildly asthmatic children. High-dose methacholine inhalation tests were performed before and 7 hr after exercise challenge. Methacholine PC20 was not changed by exercise, irrespective of exercise-induced bronchoconstriction (EIB). However, the subjects with (+)EIB displayed increased MAN after exercise, whereas those with (±)EIB or (—)EIB did not. The results showed that EIB may be followed by increased MAN but not by the change of bronchial sensitivity.     

The airways effects of inhaled chlorbutol in asthmatic subjects

Chlorbutol is an antibacterial and antifungal agent incorporated in terbutaline (Bricanyl) nebulizer solution. Ten stable atopic asthmatic subjects undertook bronchial challenge testing, according to a double-blind protocol. Patients inhaled doubling concentrations of either methacholine (0.13-4.0 mg.ml-1) or chlorbutol (0.16-5.0 mg.ml-1) for 2 min until the forced expiratory volume in one second (FEV1) had fallen by 20% from baseline. If this had not occurred following the administration of the final concentration, then this highest concentration was repeated for 4 min. The nine subjects completing the study had a geometric mean provocation concentration producing a 20% fall from baseline FEV1 (PC20) methacholine of 0.16 mg.ml-1 (range less than 0.125-0.475 mg.ml-1). After inhalation of 2.5 mg.ml-1 chlorbutol one subject experienced a fall in FEV1 greater than 20%. In the remaining eight subjects, inhalation of chlorbutol did not affect airway calibre. We conclude that chlorbutol, in the concentration present in Bricanyl nebulizer solution, has no clinically significant effect on airway calibre.     

Indices of nonspecific bronchial responsiveness in a pediatric population

A cross-sectional survey of the prevalence of asthma and bronchial hyperreactivity among schoolchildren (7 to 11 years old) was carried out in three areas of the Latium region (Central Italy). Out of 1,777 children tested with methacholine challenge (MCT), 15.1 percent had a 20 percent fall in FEV1 after a provocative concentration (PC20FEV1) of 4 mg/ml of methacholine or less; 69.7 percent had a PC20FEV1 less than 64.0 mg/ml, whereas 50.3 percent were nonresponders. Two continuous measures of bronchial responsiveness, the slope (percentage of change in FEV1 per mg/ml of methacholine) and the area under the dose response curve, were calculated in order to avoid the loss of information in nonresponders. Applying a receiver operating characteristic (ROC) curve analysis, the three estimators did not show any statistically significant difference in their overall performance in detecting asthma (ROC areas: PC20FEV1 = 0.683, slope = 0.681, area = 0.702 or asthma-like symptoms. The log transformation of slope, having a unimodal and slightly skewed shape, is an appealing continuous measure of bronchial responsiveness useful for epidemiologic studies. The final choice of an appropriate estimator of the concentration-response curve to methacholine, however, depends upon both the statistical tests or the modelling procedures to be used and clarification of the prognostic value of different indices of bronchial responsiveness.     

Lack of bronchial hyperresponsiveness to methacholine and to isocapnic dry air hyperventilation in heart/lung and double-lung transplant recipients with normal lung histology. The Paris-Sud Lung Transplant Group.

To investigate whether survivors of heart/lung and double-lung transplantations have normal or increased nonspecific bronchial responsiveness, nine heart/lung and four double-lung transplant recipients with normal lung histology underwent methacholine challenge and voluntary isocapnic dry air hyperventilation (VIH) in a randomized order at a mean time of 14.8 +/- 12.1 months after surgery. Transplant recipients were compared with 10 normal subjects and 11 patients with mild asthma. Asthmatic patients had a mean provocative concentration of methacholine inducing a 20% fall (PC20) in FEV1 of 3.4 +/- 3.6 mg/ml (SD). Seventy seven percent of the transplant recipients and 70% of the normal subjects had PC20 superior to 32 mg/ml. The percentage fall from baseline FEV1 after VIH was 12.6 +/- 10.4% in asthmatic patients as compared with 1.9 +/- 2.9% in transplant recipients (p = 0.002) and 0.45 +/- 1.2% in normal subjects (p = 0.001). The decrease in FEV1 after VIH was similar in transplant recipients and normal subjects (p = 0.14). These results show that heart/lung or double-lung transplant recipients with normal lung histology have a normal response to nonspecific bronchial stimulation.     

Duration of tachyphylaxis in response to methacholine in healthy non-asthmatic subjects

It is well recognized that bronchial responsiveness to methacholine is reduced after methacholine-induced bronchoconstriction in non-asthmatic subjects, but not in asthmatic subjects. However, it is unknown how long the methacholine tachyphylaxis lasts. The present study was conducted to elucidate duration of the methacholine tachyphylaxis in healthy non-asthmatic subjects. Measurements of methacholine responsiveness were repeated six times at intervals of 1 h and 1, 2, 3 and 7 days in eight healthy non-asthmatic young female subjects in whom methacholine concentrations causing a 20% fall in forced expiratory volume in 1 sec (FEV1; PC20-Meth) were 40 mg/mL or less. Geometric mean value (GSEM) of PC20-Meth was 10.6 (1.44) mg/mL at the first challenge, 63.4 (1.85) at the 1-h interval, 50.2 (1.67) at the 1-day interval, 49.7 (1.68) at the 2-day interval, 17.3 (1.51) at the 3-day interval and 13.1 (1.44) mg/mL at the 7-day interval. The values at intervals of 1 h to 3 days were significantly greater than the initial value. These results indicate that measurements of methacholine responsiveness should be separated by at least 7 days to avoid the tachyphylaxis when the tests are repeated in non-asthmatic subjects.     

Effect of losartan, a type 1 angiotensin II receptor antagonist, on bronchial hyperresponsiveness to methacholine in patients with bronchial asthma

It is unclear whether angiotensin II receptors are involved in bronchial hyperresponsiveness in asthmatic patients. We examined the effect of losartan, a specific angiotensin II type 1 (AT1) receptor antagonist, on bronchial responsiveness to inhaled methacholine in eight patients with stable asthma. Bronchial responsiveness to methacholine, assessed as the concentration of methacholine producing a 20% fall in FEV(1) (PC(20)-FEV(1)) and a 35% fall in standardized partial expiratory flow at 40% of FVC (PC(35)-PEF(40)), was measured on two occasions 2 wk apart. Losartan (50 mg once a day) or a placebo was orally administered for 1 wk before methacholine provocation test in a double-blind, randomized, crossover fashion. Although the PC(20)-FEV(1) values after placebo (2.037 [geometric standard error of the mean, GSEM = 0.210] mg/ml) and losartan (2.098 [GSEM, 0.239] mg/ml) were identical (p = 0.840), the geometric mean PC(35)-PEF(40) values significantly (p = 0.034) increased from 0.258 (GSEM, 0.156) mg/ml with placebo to 0.456 (GSEM, 0.186) mg/ml with losartan. We conclude that AT1 receptors are involved in bronchial hyperresponsiveness in asthmatic patients. This is the first report demonstrating the involvement of AT1 receptors in bronchial asthma.     

Agreement between spirometry and tracheal auscultation in assessing bronchial responsiveness in asthmatic children.

We have recently found that changes in lung sounds correspond well with a 20% fall in the forced expiratory volume in 1 s (FEV1) after methacholine challenge in asthmatic children. Up to now, little was known about the agreement between a 20% fall in FEV1 and a change in lung sounds after repeated bronchial challenge. In this study we investigated the agreement between the total cumulative histamine dose causing a fall in FEV1 of 20% or more (PD20) and the detection of a change in lung sounds (PDlung sounds) after two bronchial challenges on different occasions in asthmatic children. Fifteen asthmatic children (nine boys), mean age 10.8 years (range 9-15), were studied. All performed two histamine challenge tests on 2 days, with a 24 h to 1 week interval. Lung sounds were recorded over the trachea for 1 min and stored on tape. Lung sounds were analysed directly and also scored from the tape-recording by a blinded second investigator. Wheeze, cough, and an increase in respiratory rate were assessed. The relationship between PD20 and PDlung sounds was calculated by Bland and Altman's measurement of agreement. Eleven children had a positive challenge test (PD20 < or = 16.0 mg ml-1) on both test days; four had a positive challenge on one test day. In 24 out of 26 positive challenges, wheeze, cough, prolonged expiration and/or increased respiratory rate were detected one dose-step before, or at the dose-step of histamine that induced a fall in FEV1 of 20% or more. In two challenges, PD20 was not detected by a change in lung sounds. In four out of four negative challenges (PD20 > 16.0 mg ml-1) no change in lung sounds could be detected. Good agreement between the logarithm of PD20 and the logarithm of PDlung sounds was found on both test days. The mean difference was 0.04 and the limits of agreement (d +/- 2 SD of the differences) were 0.04 +/- 0.41. A good agreement was found between the total cumulative histamine dose causing a fall in FEV1 of 20% or more and the detection of a change in lung sounds after two bronchial challenges on different occasions in asthmatic children.     

Methacholine responsiveness, respiratory symptoms and pulmonary function in aluminum potroom workers

The relationship between nonspecific bronchial reactivity and work-related asthmatic symptoms was examined in a cross-sectional study of 337 aluminium potroom workers by a shortened method of continuous methacholine nebulization. The provocative concentration producing a 20% fall in forced expiratory volume in one second (FEV1) (PC20) was less than or equal to 8 mg.ml-1 (hyperresponsiveness) in 17 workers (5%), whilst minor responsiveness (8 mg.ml-1 less than PC20 less than 32 mg.ml-1) was present in 24 subjects (7%). The prevalence of work-related asthmatic symptoms was 9%. Female sex, ex-smoker and airflow limitation were significant predictors of methacholine responsiveness (p less than 0.05). In a multiple logistic regression analysis the odds ratios (OR) for work-related asthmatic symptoms was 10.8 (95% confidence interval: 2.9-40.6) for hyperresponsiveness and 4.4 (95% confidence interval: 1.2-16.4) for minor responsiveness. The sensitivity, specificity and predictivity of PC20 less than 32 mg.ml-1 for work-related asthmatic symptoms were 35, 92 and 35%, respectively, whilst the agreement, when adjusted for the by chance expectation, was 0.27 (95% confidence interval: 0.10-0.54). Although a significant association was found between bronchial reactivity and work-related asthmatic symptoms, the usefulness of the methacholine test as a tool for detection of work-related asthmatic symptoms appears to be of limited value due to its low sensitivity.     

Predictors of late asthmatic response. Logistic regression and classification tree analyses

To identify predictors of the late asthmatic response (LAR), we reviewed data from 60 asthmatic subjects who had undergone allergen challenge over the past 5 yr (33 females, age 31.4 +/- 6.7 yr [mean +/- SD], FEV(1) 90% +/- 14% predicted). Variables considered likely predictors of LAR included baseline FEV(1), PC(20) methacholine (PC(20)), sputum eosinophil percent, and the decrease in FEV(1) within 20 min of allergen challenge. A LAR (FEV(1) >/= 15% fall between 3 and 7 h after challenge) was documented in 57% of subjects. A variety of logistic regression methods revealed a significant inverse association between LAR and PC(20) (odds ratio [OR] = 0.14 [95% CI = 0.03-0.66]) and a positive association between LAR and the decrease in FEV(1) at 20 min (OR = 1.18 [1.04 -1.33]). Classification tree analysis revealed that a threshold of 0.25 mg/ml for PC(20) was most predictive of LAR; LAR developed in 87% of those with PC(20) 0.25 mg/ml (n = 37). Notably, in subjects with PC(20) > 0.25 mg/ml, the incidence of LAR increased from 38% to 57% if the allergen-induced decline in FEV(1) at 20 min was >/= 27%. Surprisingly, baseline FEV(1) and percent eosinophils in induced sputum were not significantly associated with LAR. We conclude that a threshold value of 0.25 mg/ml for PC(20) methacholine is a good predictor of LAR. Measuring the PC(20) methacholine may be useful as a screening method to improve the efficiency of identifying asthmatic subjects with a LAR.     

Need for monitoring nonspecific bronchial hyperresponsiveness before and after isocyanate inhalation challenge

BACKGROUND: Specific and nonspecific bronchial responsiveness may decline or disappear after cessation of exposure in the workplace in patients with occupational asthma, leading to false-negative specific inhalation challenge (SIC) results. METHODS: Twenty-two patients with suspected diisocyanate-induced asthma were studied. SIC with diisocyanates (toluene diisocyanate [TDI] or hexamethylene diisocyanate [HDI]) was carried out in a 7-m(3) dynamic chamber up to a maximum concentration of 19 parts per billion for 120 min. Methacholine inhalation challenges were performed before and 24 h after SIC with TDI or HDI. Patients who did not show an asthmatic reaction after SIC but had a greater than twofold reduction in provocative concentration of methacholine causing a 20% fall in FEV(1) (PC(20)) after the first isocyanate challenge underwent a second isocyanate SIC 2 days later. RESULTS: The first SIC with isocyanates elicited an asthmatic reaction in 13 patients (59%). In five patients who did not show an asthmatic reaction after the first SIC, PC(20) exhibited more than a twofold reduction. In three of the five patients, a second SIC with isocyanates elicited an immediate positive asthmatic reaction. Therefore, 3 of 16 patients (19%) were ultimately shown to have bronchial responsiveness to isocyanate; occupational asthma was demonstrated due to post-SIC monitoring of bronchial hyperresponsiveness to methacholine. CONCLUSION: PC(20) should be systematically assessed before and after SIC with isocyanates in the absence of significant changes in FEV(1) during SIC to avoid false-negative results.     

Bronchial challenge tests in patients with asthma sensitized to cats: the importance of large particles in the immediate response

Our aim was to compare bronchial responses to major cat allergen (Fel d 1) in individuals with intermittent asthma sensitized to cats (19 subjects) according to the droplet particle size. We used three nebulizers, which delivered particles with mass median aerodynamic diameters of 1.4, 4.8, and 10.3 microm. A dosimeter nebulizer was used. The cat allergen was diluted to obtain the same amount of Fel d 1 per puff with each nebulizer. Each patient underwent three methacholine bronchial challenge tests (BCT), each followed 24 hours later by a cat allergen BCT, each performed with a different nebulizer (randomly selected each time, with patient and tester always blinded). Subjects did not differ for methacholine responsiveness, FEV1, mean forced expiratory flow during the middle half of the FVC (FEF25-75), PEF, or dyspnea (Borg scale) before any of the three cat BCTs. Cat allergen PD20 was 271 ng of Fel d 1 with the 1.4 microm nebulizer, 46 ng with the 4.8 microm nebulizer, and 13.5 ng with the 10.3 microm nebulizer (p = 0.00001). Inhalation of small particles (1.4 microm) resulted in significantly lower FEF25-75 24 hours after provocation than large particles did. In conclusion, immediate bronchial response appears to be localized in large airways, and the use of large particles is more appropriate for cat allergen BCTs.     

Effect of inhaled beclomethasone dipropionate on bronchial hyperreactivity in asthmatic children during maximal allergen exposure

In this double blind study we evaluated the effect of a 2 months long treatment with inhaled beclomethasone dipropionate (300 micrograms/day) on methacholine responses in asthmatic children, during a period of maximal allergen exposure. Baseline values of methacholine PC20-FEV1 were 0.66 +/- 0.22 mg/mL (mean +/- SEM) in 10 children treated with the active drug and 0.78 +/- 0.21 mg/mL in 10 children treated with placebo. After 1 month of treatment PC20-FEV1 was 1.91 +/- 0.64 and 0.80 +/- 0.33 mg/mL, respectively, in the groups treated with beclomethasone versus placebo. A statistically significant reduction in bronchial hyperreactivity (PC20-FEV1, 5.49 +/- 1.86 mg/mL) but no systemic side effects were observed after 2 months of treatment with beclomethasone dipropionate. This is compared with a PC20-FEV1 of 1.38 +/- 0.52 mg/mL in the placebo group. The results confirm the effect of inhaled corticosteroids in reducing bronchial hyperreactivity, even during a period of maximal allergen exposure.