EXERCISE-INDUCED AIRWAY OBSTRUCTION

Predictors of exercise-induced bronchoconstriction in subjects with mild asthma

Background

Physical effort is capable of triggering airway obstruction in asthmatics, the so-called exercise-induced bronchoconstriction in asthma (EIBa). This study was performed in subjects with mild persistent asthma, aiming to find predictors for developing EIBa.

Methods

In 20 subjects with mild asthma, measurements of baseline functional respiratory parameters and airways responsiveness by a methacholine challenge were obtained on the first day. A maximal, symptom-limited incremental cardiopulmonary exercise test (CPExT) was performed the day after, with subsequent, repeated maneuvers of maximal full forced expiration to monitor the FEV₁ change at 1,3,5,7,10 and 15 min after the end of the exercise.

Results

19 subjects completed the two-days protocol. No functional parameters both at rest and during effort were useful to predict EIBa after stopping exercise. In asthmatics with EIBa, mean Inspiratory Capacity (IC) did not increase with increasing ventilatory requirements during CPExT because 6 of them (50%) displayed dynamic pulmonary hyperinflation (DH), as documented by their progressive increase of end-expiratory lung volume. This subgroup, showing earlier post-exercise FEV₁ fall, had significantly lower forced mean expiratory flow between 25% and 75% of forced vital capacity (FEF_25-75%) at rest (p < 0.05) and higher airways responsiveness, expressed as PD₂₀FEV₁ (p < 0.05) as compared with other asthmatics with EIBa.

Conclusions

No functional respiratory parameters seem to predict EIBa in mild asthmatics. However, in those with EIBa, a subgroup developed DH during exercise, and this was associated with a baseline reduced forced expiratory flow rates at lower lung volumes and higher airway hyperresponsiveness, suggesting a prominent small airways impairment.

Dynamic hyperinflation in patients with asthma and exercise-induced bronchoconstriction

BACKGROUND

Little is known about the behavior of operative lung volumes during exercise in patients with asthma and exercise-induced bronchoconstriction (EIB).

OBJECTIVE

To compare the presence of dynamic hyperinflation (DH) in patients with mild asthma with and without EIB and in healthy individuals and to relate the changes in end-expiratory lung volume (EELV) with postexercise airflow reduction.

METHODS

A total of 122 consecutive stable patients (>12 years of age) with mild asthma and 38 controls were studied. Baseline lung volumes were measured, and all patients performed an exercise bronchial challenge. At each minute of exercise, EELV and end-inspiratory lung volume (EILV) were estimated from inspiratory capacity measurements to align the tidal breathing flow-volume loops to within the maximal expiratory curve.

RESULTS

DH was more frequent in patients with asthma and EIB (76%) than in patients with asthma but without EIB (11%) or controls (18%). The EELV increased in patients with asthma and EIB and decreased in patients with asthma without EIB and controls during exercise. In the patients with asthma, the decrease in forced expiratory volume in 1 second after the exercise challenge correlated with age (r = -0.179, P = .05), baseline forced vital capacity (r = 0.255, P = .005), EELV increase (r = 0.447, P < .001), and EILV increase (r = 0.246, P = .007). Age, baseline forced vital capacity, and magnitude of DH were retained as independent predictors of EIB intensity.

CONCLUSION

In patients with asthma and EIB, the development of DH is very frequent and related to the intensity of postexercise bronchoconstriction. This finding could implicate DH in the development of EIB.

Introduction to asthma and phenotyping

Asthma is an inflammatory disorder characterized by airway obstruction, airway hyperresponsiveness, and airway inflammation, all of which are variable among patients and variable in time within any specific patient. Understanding the mechanism that underlies this observed variability, and using that understanding to advance the science of asthma and the care of asthmatic patients, is an essential purpose of developing phenotypes. Clinical phenotypes have been used for decades, but overlap each other, and do not map cleanly to either pathophysiologic mechanism or with therapeutic response. Molecular phenotyping, although as yet only partially developed, offers the promise of dissecting the mechanistic underpinnings of the variability of asthma and of providing predictive therapeutics for the benefit of patients with this common and troubling disease.

Exercise-induced bronchoconstriction in elite long-distance runners in Brazil

OBJECTIVE

To determine the prevalence of exercise-induced bronchoconstriction among elite long-distance runners in Brazil and whether there is a difference in the training loads among athletes with and without exercise-induced bronchoconstriction.

METHODS

This was a cross-sectional study involving elite long-distance runners with neither current asthma symptoms nor a diagnosis of exercise-induced bronchoconstriction. All of the participants underwent eucapnic voluntary hyperpnea challenge and maximal cardiopulmonary exercise tests, as well as completing questionnaires regarding asthma symptoms and physical activity, in order to monitor their weekly training load.

RESULTS

Among the 86 male athletes recruited, participation in the study was agreed to by 20, of whom 5 (25%) were subsequently diagnosed with exercise-induced bronchoconstriction. There were no differences between the athletes with and without exercise-induced bronchoconstriction regarding anthropometric characteristics, peak oxygen consumption, baseline pulmonary function values, or reported asthma symptoms. The weekly training load was significantly lower among those with exercise-induced bronchoconstriction than among those without.

CONCLUSIONS

In this sample of long-distance runners in Brazil, the prevalence of exercise-induced bronchoconstriction was high.

Treatment options for the management of exercise-induced asthma and bronchoconstriction

Treatment for exercise-induced bronchospasm and exercise-induced asthma includes both pharmacologic and nonpharmacologic options. Pharmacologic agents that have been proven to be effective for treating these conditions include short- and long-acting β2-adrenoceptor agonists, mast cell-stabilizing agents, anticholinergics, leukotriene receptor antagonists, and inhaled corticosteroids (ICS). When selecting the most appropriate medication, factors to consider include the effectiveness of each, the duration of action, frequency of administration, potential side effects, and tolerance level. Long-acting β2-adrenoceptor agonists should not be used without ICS. Nonpharmacologic treatments include physical conditioning, incorporating a warm-up before and a cool-down period after exercise, performing nasal breathing, avoiding cold weather or environmental allergens, using a face mask or other aid to warm and humidify inhaled air, and modifying dietary intake. The data to support nonpharmacologic treatments are limited; however, they are routinely recommended because of the low risk associated with their use. This article highlights the advantages and limitations of each treatment option.

Desempenho de uma escala analógica visual legendada na determinação do grau de dispneia durante teste de broncoespasmo induzido por exercício em crianças e adolescentes asmáticos

OBJETIVO: Existe uma relação indireta entre a obstrução das vias aéreas em asma e a intensidade de falta de ar (dispneia). Uma escala visual analógica legendada de dispneia com escore de 0-3 pontos tem sido amplamente utilizada na avaliação da broncoconstrição, embora a percepção de tal obstrução seja muito variável. O objetivo deste estudo foi determinar se crianças e adolescentes são capazes de perceber a broncoconstrição aguda induzida por exercício (BAIE), bem como medir o poder discriminatório de uma escala visual analógica legendada de dispneia em relação à intensidade de BAIE. MÉTODOS: Estudo transversal com 134 crianças e adolescentes asmáticos que foram submetidos a um teste de broncoespasmo induzido por seis minutos de exercício em um cicloergômetro. A intensidade da dispneia foi determinada utilizando-se uma escala visual analógica legendada de dispneia antes de cada determinação de VEF1. A escala tem um escore de 0-3 pontos, com desenhos em uma sequência lógica variando entre "sem sintomas" e "dispneia grave". As variáveis foram determinadas no momento basal, assim como em 5, 10 e 20 minutos após o término do teste de exercício. A acurácia da escala de dispneia em detectar o grau de BAIE foi determinada através de curvas ROC para a queda de VEF1 após o exercício, usando pontos de corte de 10%, 20%, 30% e 40%. RESULTADOS: Dos pacientes selecionados, 111 completaram o estudo, e 52 (46,8%) apresentaram BAIE. A área sob a curva ROC progressivamente aumentou com o aumento do grau de broncoconstrição. CONCLUSÕES: Em crianças e adolescentes asmáticos, a acurácia desta escala de dispneia melhora com o aumento do percentual de queda em VEF1 após o exercício. Entretanto, o valor preditivo da escala é subótimo quando a porcentagem de queda em VEF1é menor.

Efeito do tratamento clínico de um corredor de longa distância com broncoespasmo induzido pelo exercício: relato de caso

O broncoespasmo induzido pelo exercício (BIE) é uma condição que se caracteriza pelo estreitamento transitório das vias aéreas durante ou após o esforço físico e afeta principalmente portadores de asma. Em atletas profissionais que praticam esportes de alta intensidade, a prevalência também é alta; no entanto, seu diagnóstico permanece subestimado. O presente estudo descreve o caso de um atleta do sexo masculino, 23 anos, corredor de longa distância sem histórico de asma, que após um teste gradual de exercício apresentou chiado no peito e queda da função pulmonar. Após um teste específico, o atleta foi diagnosticado como BIE positivo. Iniciou-se, então, um tratamento clínico com broncodilatador e após 30 dias verificou-se melhora importante em seu consumo máximo de oxigênio, obtido no pico do esforço (VO2 pico).

Response to bronchodilators after exercise challenge predicts bronchial hyperreactivity

BACKGROUND

Some subjects with suspected asthma and a negative exercise challenge test (ECT) demonstrate improved expiratory flow rates after administration of bronchodilators (BD) at the end of the ECT (unpublished observation). This study investigated whether this response predicts the presence of bronchial hyperreactivity (BHR).

PATIENTS AND METHODS

The study population included 133 young adults (29.4% women) 21.1 +/- 4.2 years of age who underwent ECT and a methacholine challenge test (MCT). A receiver-operator-characteristic curve was used to calculate the optimal cutoff level of the response to BD as a predictor of BHR according to MCT.

RESULTS

Using a MCT cutoff level of PC(20) </= 4 mg/mL showed BHR in 12.8% of subjects. Failure to improve FEV(1) by 8% after BD administration predicted the absence of BHR with sensitivity, specificity, and positive and negative predictive values of 76.5%, 68.4%, 25.3%, and 95.5%, respectively. Avoiding MCT in subjects with less than 8% response to BD would have saved 62.5% of the MCTs and would have missed only four (3%) patients with BHR.

CONCLUSIONS

BD should be administered routinely after ECT, as the response may be used as a simple, inexpensive tool to predict BHR in young patients and may substantially reduce the number of unnecessary MCTs.

The role of endothelium-derived mediators in exercise-induced bronchoconstriction

BACKGROUND

Exercise-induced bronchoconstriction (EIB) is a highly prevalent condition whose pathogenesis and effect on airways remain unclear. The aim of the study was to evaluate the changes in endothelial-derived mediators following intensive exercise in asthmatic patients.

METHODS

The study was conducted in a group of 25 asthmatic patients (15 with EIB, 10 without EIB) and 8 healthy volunteers. Changes induced by intensive exercise in the plasma concentrations of endothelin-1 (ET-1), thrombomodulin and soluble E-selectin were determined. Moreover, the possible correlations of these measurements with the results of baseline lung function, bronchial hyperreactivity (BHR), exhaled nitric oxide (F(ENO)), baseline eosinophil cationic protein, peripheral blood eosinophilia and total IgE were investigated.

RESULTS

In the group of asthmatics with EIB, statistically significantly higher baseline concentrations of ET-1 and soluble E-selectin compared with asthmatics with negative exercise test results were revealed. In this group of patients, ET-1, thrombomodulin and soluble E-selectin concentrations significantly increased after exercise. Baseline concentrations of ET-1 as well as an increase in soluble E-selectin concentrations 60 min after exercise showed a statistically significant correlation with baseline eosinophil cationic protein, F(ENO) and BHR. The increase in plasma concentrations of ET-1 15 min after exercise and soluble E-selectin 60 min after exercise showed a statistically significant correlation with the increase in F(ENO) and BHR to histamine 24 h after exercise.

CONCLUSIONS

We suggest that during EIB changes in the function of pulmonary endothelium occur and these changes may influence inflammation of the airway and remodeling in asthmatic patients.

Increased airway hyperreactivity with the M40 protective mask in exercise-induced bronchospasm

OBJECTIVE

Exercise-induced bronchospasm (EIB) has a prevalence of 6% to 7% in United States Army personnel and 3% to 13% in professional athletes. There are reported concerns that military personnel with EIB will have increased airway hyperreactivity or significant dyspnea while wearing the standard military M40 protective mask. The objective of this study is to determine whether the M40 protective gas mask increases airway hyperreactivity in military personnel with exertional dyspnea and the diagnosis of EIB.

METHODS

Ten active duty military with EIB (defined as history of exertional dyspnea, normal spirometry, and reactive methacholine challenge test) and 10 normal control subjects were evaluated. Both the participants and control subjects underwent baseline exercise challenge testing (ECT) with and without the M40 protective mask. Forced expiratory volume in one second (FEV1) (percent predicted) post ECT was compared to baseline FEV1 within and between groups along with exercise time.

RESULTS

There was no statistical difference in between individuals and between groups wearing the M40 mask. None of the study group had a positive ECT exercising without the M40 mask while 20% of the study group with EIB had a positive ECT wearing the M40 mask.

CONCLUSION

Military personnel with EIB who exercised with the M40 protective mask did not overall have significantly increased airway hyperreactivity compared to control subjects. Screening ECT may be beneficial in identifying those susceptible persons who report symptoms while wearing the M40 protective mask.

Efficacy of a heat exchanger mask in cold exercise-induced asthma

STUDY OBJECTIVES

To determine the efficacy of a novel mask device in limiting cold air exercise-induced decline in lung function in subjects with a history of exercise-induced asthma (EIA).

SETTING

In spite of appropriate medical therapy, many asthma patients are limited in cold weather activities.

DESIGN

In study 1, 13 asthmatic subjects performed two randomized, single-blind treadmill exercise tests while breathing cold air (- 25 to - 15 degrees C) through a placebo or active heat exchanger mask. In study 2, five subjects with EIA performed three treadmill exercise tests while breathing cold air: one test using the heat exchanger mask, one test without the mask but with albuterol pretreatment, and one test with neither the mask nor albuterol pretreatment (unprotected exercise). For all studies, spirometry was performed before and at 5, 15, and 30 min after exercise challenge.

PATIENTS

For both studies, a total of 15 subjects with a history of asthma symptoms during cold air exercise were recruited.

RESULTS

In study 1, the mean decrease (+/- SE) in FEV1 was 19 +/- 4.9% with placebo, and 4.3 +/- 1.6% with the active device (p = 0.0002). The mean decrease in maximum mid-expiratory flow (FEF(25-75)) was 31 +/- 5.7% with placebo and 4.7 +/- 1.7% with the active device (p = 0.0002). In study 2, the mean decrease in FEV1 was 6.3 +/- 3.9%, 11 +/- 3.7%, and 28 +/- 10% for the heat exchanger mask, albuterol pretreatment, and unprotected exercises, respectively (p = 0.4375 for mask vs albuterol, p = 0.0625 for mask vs unprotected exercise). The mean decrease in FEF(25-75) was 10 +/- 4.8%, 23 +/- 6.0%, and 36 +/- 11%, respectively (p = 0.0625 for mask vs albuterol, p = 0.0625 for mask vs unprotected exercise).

CONCLUSIONS

This heat exchanger mask blocks cold exercise-induced decline in lung function at least as effectively as albuterol pretreatment.

Clinical Role of Rapid-Incremental Tests in the Evaluation of Exercise-Induced Bronchoconstriction

STUDY OBJECTIVE

To determine whether rapid-incremental work rate (IWR) testing would be as useful as standard high-intensity constant work rate (CWR) protocols in eliciting exercise-induced bronchoconstriction (EIB) in susceptible subjects.

DESIGN AND SETTING

A cross-sectional study performed in a clinical laboratory of a tertiary, university-based center.

SUBJECTS AND MEASUREMENTS

Fifty-eight subjects (32 males, age range, 9 to 45 years) with suspected EIB were submitted to CWR testing (American Thoracic Society/European Respiratory Society guidelines) and IWR testing on different days; 21 subjects repeated both tests within 4 weeks. Spirometric measurements were obtained 5, 10, 15, and 20 min after exercise; a FEV1 decline > 10% defined EIB.

RESULTS

Twenty-seven subjects presented with EIB either after CWR or IWR testing; 21 subjects had EIB in response to both protocols (kappa = 0.78, excellent agreement; p < 0.001). Of the six subjects in whom discordant results were found, two had EIB only after IWR. Assuming CWR as the criterion test, IWR combined high positive and negative predictive values for EIB detection (91.3% and 88.6%, respectively). Tests reproducibility in eliciting EIB were similar (kappa = 0.80 and 0.72 for CWR and IWR, respectively; p < 0.001). Total and intense (minute ventilation > 40% of maximum voluntary ventilation) ventilatory stresses did not differ between EIB-positive and EIB-negative subjects, independent of the test format. There were no significant between-test differences on FEV(1) decline in EIB-positive subjects (25.7 +/- 10.8% vs 23.7 +/- 10.0%, respectively; p > 0.05). Therefore, no correlation was found between exercise ventilatory response and the magnitude of EIB after either test (p > 0.05).

CONCLUSIONS

Rapid-incremental protocols (8 to 12 min in duration) can be as useful as high-intensity CWR tests in diagnosing EIB in susceptible subjects. Postexercise spirometry should be performed after incremental cardiopulmonary exercise testing when EIB is clinically suspected.

Avaliação de um programa de treinamento físico por quatro meses para crianças asmáticas

OBJETIVO: Avaliar condicionamento físico e força muscular de crianças asmáticas antes e depois de quatro meses de participação num programa de exercícios físicos. MÉTODOS: Dois grupos de crianças com asma moderada e idade entre oito e onze anos foram formados. Ambos realizaram testes pré e pós-treinamento físico, duas vezes por semana, por quatro meses, em sessões de 90 minutos, com exercícios em solo e em água. Orientações sobre asma, seu controle e tratamento foram fornecidos a ambos os grupos. RESULTADOS: Na avaliação final, observou-se aumento das variáveis antropométricas em ambos os grupos. O grupo exercício apresentou melhora significativa na distância percorrida em nove minutos (inicial 1,333 + 0,03 km e final 1,440 + 0,03 km; p < 0,05), número de flexões abdominais (inicial 24,3 + 1,4 abdominais e final 33,2 + 1,1 abdominais; p < 0,05), pressão inspiratória máxima (inicial 73 + 5 cmH2O e final 103 + 5 cmH2O; p < 0,05), pressão expiratória máxima (inicial 75 + 4 cmH2O e final 102 + 4 cmH2O; p < 0,05) e na freqüência cardíaca de repouso (inicial 84,3 + 1,6 bpm e final 77,1 + 2,7 bpm; p < 0,05). O grupo controle não mostrou variação significativa em nenhum desses parâmetros. CONCLUSÃO: Um programa de treinamento físico com menor freqüência e maior duração de cada sessão, para facilitar a participação das crianças, propicia melhora do condicionamento físico e aumento de força muscular em crianças asmáticas.

Airway hyperresponsiveness by methacholine challenge testing following negative exercise challenge

BACKGROUND

Exercise challenge testing (ECT) to diagnose exercise-induced bronchospasm has been demonstrated to be an insensitive screening test to demonstrate the presence or absence of airway hyperreactivity. Previous studies have not compared this procedure to methacholine challenge testing (MCT) in a clinical setting.

OBJECTIVE

To determine the frequency of positive MCT in subjects with exertional dyspnea, normal baseline spirometry, and negative ECT.

METHODS

Observational study of 215 military patients at an Army Community Hospital referred for evaluation of exertional dyspnea with normal baseline spirometry. Subjects were further evaluated with ECT on a graded treadmill with pre- and postexercise spirometry. Those without evidence of bronchial hyperreactivity as defined by a 15% decrease in FEV1 postexercise were evaluated with methacholine challenge testing (MCT).

RESULTS

Two hundred ten military subjects were evaluated. Eighty-two patients underwent ECT as the only method of bronchoprovocation testing with 25 positive tests (57 were negative but not referred for further testing). The remaining 128 patients with a negative ECT underwent MCT. Seventy-six (59%) had a negative MCT and 52 (41%) had a positive MCT. Of the positive MCT studies, 74% were positive at a methacholine concentration of 2.5 mg/mL or less.

CONCLUSIONS

Our study demonstrates that a significant number of patients being evaluated for exertional dyspnea will have a positive MCT after a negative ECT. Our findings lead us to question the utility of ECT as an initial diagnostic test for the exercise-induced bronchospasm.

Weight-loss practices and asthma: findings from the behavioral risk factor surveillance system

OBJECTIVE

To describe weight-control practices and receipt of weight-loss advice among obese people with asthma.

RESEARCH METHODS AND PROCEDURES

We analyzed data from the 2000 Behavioral Risk Factor Surveillance System.

RESULTS

Among 13953 participants with current asthma, 27.3% had a body mass index of >or=30 kg/m2. Overall, 48.1% of participants with asthma reported trying to lose weight (64.1% among overweight or obese participants and 72.9% among obese participants). Among participants with asthma who were trying to lose or maintain weight, 74.7% reported trying to reduce their energy and/or fat intake, and 57.8% reported using physical activity. Approximately 29.7% were using the recommended combination of energy and/or fat intake reduction and physical activity of >or=150 min/wk. During the 12 months before the interview, 16.2% of overweight and 44.9% of obese participants with asthma reported receiving advice to lose weight. Among obese participants receiving weight-loss advice, 82.9% reported trying to lose weight compared to 63.8% of participants who did not receive such advice.

DISCUSSION

Health professionals can play an important role in educating their patients with asthma about the importance of weight control and assisting their overweight and obese patients in setting appropriate weight goals and helping them achieve those goals.

Exercise-induced asthma: diagnosis and management

OBJECTIVE

To review the diagnosis and management of exercise-induced asthma (EIA).

DATA SOURCES

Computer-assisted literature searches on MEDLINE for articles, abstracts, and other relevant data on exercise-induced asthma

STUDY SELECTION

Published articles, abstracts, and conference proceedings were selected.

RESULTS

EIA is seen in 40 to 90% of asthmatic patients. Exercise can be the sole trigger or be one of multiple triggers of asthma exacerbations. A good history and physical examination can diagnose most cases of EIA. Spirometry can confirm the diagnosis. Exercise testing may be necessary in certain cases. Prevention through both pharmacologic and nonpharmacologic measures is the key to EIA management. Inhaled beta-agonists remain the medications of choice for EIA prophylaxis. Inhaled cromolyn and antileukotrienes are alternatives. Good long-term control of asthma with anti-inflammatory medications such as inhaled steroids will also decrease the incidence of EIA.

CONCLUSIONS

Early diagnosis and proper preventive and maintenance therapy can reduce episodes of EIA and enable patients to continue to engage in sports and lead an active life.

Complement-dependent immune complex-induced bronchial inflammation and hyperreactivity

Bronchoconstriction responses in the airway are caused by multiple insults and are the hallmark symptom in asthma. In an acute lung injury model in mice, IgG immune complex deposition elicited severe airway hyperreactivity that peaked by 1 h, was maintained at 4 h, and was resolved by 24 h. The depletion of complement with cobra venom factor (CVF) markedly reduced the hyperreactive airway responses, suggesting that complement played an important role in the response. Blockade of C5a with specific antisera also significantly reduced airway hyperreactivity in this acute lung model. Complement depletion by CVF treatment significantly reduced tumor necrosis factor and histamine levels in bronchoalveolar lavage fluids, correlating with reductions in airway hyperreactivity. To further examine the role of specific complement requirement, we initiated the immune complex response in C5-sufficient and C5-deficient congenic animals. The airway hyperreactivity response was partially reduced in the C5-deficient mice. Complement depletion with CVF attenuated airway hyperreactivity in the C5-sufficient mice but had a lesser effect on the airway hyperreactive response and histamine release in bronchoalveolar lavage fluids in C5-deficient mice. These data indicate that acute lung injury in mice after deposition of IgG immune complexes induced airway hyperreactivity that is C5 and C5a dependent.

Clinical evidence with montelukast in the management of chronic childhood asthma

OBJECTIVE

The aim of this article is to review data on the efficacy and safety of montelukast in the treatment of children with asthma.

METHODOLOGY

Available published literature, including published abstracts, is reviewed.

RESULTS

In patients aged 6 to 14 years with asthma (n = 27), montelukast 5mg demonstrated a significant decrease in exercise-induced bronchoconstriction 20 to 24 hours postdose after 2 days of treatment. For children with chronic asthma, only one study of the regular use of a leukotriene receptor antagonist has been published. The efficacy and safety of montelukast in children aged 6 to 14 years with asthma (n = 336) were studied during an 8-week, double-blind, placebocontrolled trial. There was a significantly greater improvement in forced expiratory volume in 1 second (FEV1) from baseline for the montelukast group (8.23%) compared with the placebo group (3.58%). There was a significant decrease in the use of a 3-agonist for symptom relief, as well as in the percentage of days and percentage of patients with asthma exacerbations. An asthma specific quality-of-life (QOL) questionnaire revealed a significant overall improvement in QOL and a significant improvement in the QOL domains for symptoms, activity and emotions in montelukast recipients. There was no significant difference between montelukast and placebo recipients in the frequency of adverse events, with the exception of allergic rhinitis, which was more prevalent in the placebo group. An open label follow-up of patients from the above study was undertaken. The effect of montelukast on FEV1 was consistent for up to 1.4 years, with the increase in FEV1 being not significantly different from that in a small control group treated with inhaled beclomethasone dipropionate. QOL remained significantly improved during the open treatment period.

CONCLUSIONS

Montelukast appears effective and safe for the treatment of children with asthma.

Exercise-induced bronchospasm in children: effects of asthma severity

The prevalence of exercise-induced bronchospasm (EIB) in asthmatic individuals has been reported to vary from 40% to 90%. There are, however, few studies addressing the effects of asthma severity on airway responsiveness to exercise. The purpose of the present study was to investigate the effects of asthma severity on EIB in children. We studied 164 children classified as having intermittent (n = 63), mild persistent (n = 30), moderate persistent (n = 40), and severe persistent asthma (n = 31) according to the Global Initiative for Asthma classification. Subjects exercised for 6 min on a cycle ergometer at 80% of their maximum heart rate, and spirometry was performed before and 5, 10, and 20 min after exercise challenge. The prevalence of EIB in children with moderate or severe persistent asthma was significantly greater than in children with intermittent asthma (p < 0.001). EIB-positive children with intermittent asthma exhibited smaller changes in FEV1 than children in the other three groups (p < 0.001). There was no significant relationship between baseline FEV1 and the decline in FEV1 after exercise. We conclude that the prevalence of EIB is greater in children with more severe asthma, and that the intensity of response to exercise is not consistently related to the clinical severity of asthma.

Expired nitric oxide after bronchoprovocation and repeated spirometry in patients with asthma

Compared with normal individuals, subjects with asthma have elevated levels of expired nitric oxide (NO). These levels are hypothesized to reflect the degree of airway inflammation. Expired NO levels rise during the late phase of allergen challenge and decrease in asthmatics after steroid treatment. Isocapnic cold air hyperventilation (ISH) is believed to cause airway narrowing through noninflammatory mechanisms. We measured mixed expired NO in 10 individuals with atopic asthma who underwent both ISH challenge and allergen challenge, and compared these measurements with the change in expired NO that occurred after serial spirometry alone. We found that ambient NO levels affected mixed expired NO. Controlling for inspired NO, we found that repeated spirometry alone produced a significant fall in mixed expired NO (p < 0.01) that was maximal after 30 min (36.6 +/- 8.5% fall). After allergen and ISH challenges, expired NO was elevated relative to levels after repeated spirometry (p < 0.01 and p = 0.065, respectively). In addition, we found that prechallenge expired NO levels were significantly correlated with the magnitude of the late fall in FEV1 following allergen challenge (r = 0.80, p < 0.01). These data demonstrate that repeated spirometry results in reduced mixed expired NO and suggest that both ISH and allergen-induced bronchoconstriction share pathobiologic mechanisms that produce increases in mixed expired NO.