Heterogeneity of mechanisms in exercise induced asthma

Down-Regulation of Cough during Exercise Is Less Frequent in Healthy Children than Adults. Role of the Development and/or Atopy?

Cough is typically associated with physical activity in children with asthma, but the characteristics of the relationship between cough and exercise has not been established under physiological conditions. The aim of the study was to describe the effect of exercise on the reflex cough response elicited by a single breath of capsaicin in non-asthmatic children. A group of non-asthmatic adults was studied as reference. Thirty children and 29 adults were recruited. The cough reflex sensitivity to capsaicin was first determined to establish the dose that provokes 5 cough efforts (C5). The number of coughs elicited by C5 (NC5) was then compared at baseline and during a standardized submaximal treadmill exercise. Data are expressed as median (interquartile range). Children and adults showed a significant decrease in NC5 (respectively from 5.0 (4.0–6.0) to 2.5 (2.0–4.0), p < 0.0005 and from 6.0 (5.0–7.0) to 2.0 (0.0–3.0, p < 0.0005). During exercise, NC5 was observed to decrease in all adult subjects, but in only 24/30 children (80%, p = 0.02). A trend for a higher incidence of personal and familial atopy was observed in children that lacked cough down-regulation during exercise compared with other children. It is concluded that the cough reflex response to capsaicin is down regulated by exercise in both children and adults. The effect however is less consistently observed in the former. The difference may reflect maturation of descending inhibitory pathways of the cough reflex, but may also be associated to atopy. The data stress the importance of assessing the time relationship of cough and exercise in questionnaire studies of asthma.

Mast cells in asthma--state of the art

Mast cells (MCs) play a central role in tissue homoeostasis, sensing the local environment through numerous innate cell surface receptors. This enables them to respond rapidly to perceived tissue insults with a view to initiating a co-ordinated programme of inflammation and repair. However, when the tissue insult is chronic, the ongoing release of multiple pro-inflammatory mediators, proteases, cytokines and chemokines leads to tissue damage and remodelling. In asthma, there is strong evidence of ongoing MC activation, and their mediators and cell-cell signals are capable of regulating many facets of asthma pathophysiology. This article reviews the evidence behind this.

Respiratory disorders in endurance athletes - how much do they really have to endure?

Respiratory disorders are often a cause of morbidity in top level endurance athletes, more often compromising their performance and rarely being a cause of death. Pathophysiological events occurring during exercise, such as bronchospasm, are sometimes followed by clear pathological symptoms represented by asthma related to physical exertion or rarely by pulmonary edema induced by a strenuous effort. Both bronchospasm and the onset of interstitial edema induced by exercise cannot be considered pathological per se, but are more likely findings that occur in several healthy subjects once physical exhaustion during exertion has been reached. Consequently, we get a vision of the respiratory system perfectly tailored to meet the body's metabolic demands under normal conditions but which is limited when challenged by strenuous exercise, in particular when it happens in an unfavorable environment. As extreme physical effort may elicit a pathological response in healthy subjects, due to the exceeding demand in a perfectly functional system, an overview of the main tools both enabling the diagnosis of respiratory impairment in endurance athletes in a clinical and preclinical phase has also been described.

Vernal keratoconjunctivitis in school children in Rwanda and its association with socio-economic status: a population-based survey

Vernal keratoconjunctivitis (VKC) is an allergic eye disease and an important cause of hospital referral among children in Africa and Asia. Hospital-based studies have suggested a role for parasites in its pathogenesis. To determine the prevalence and risk factors for VKC in Central Africa, we conducted a nested population-based case control study in Rwanda, involving randomly selected primary schools from different environments (rural/urban) and climate. A prevalence of VKC of 4.0% (95% confidence interval 3.3-4.7%) was found among 3,041 children studied (participation rate 94.7%). The intestinal parasitic burden was not related to VKC. Besides hot dry climate (odds ratio [OR] = 1.5, P = 0.05) and male gender (OR = 1.7, P = 0.005), multivariate analysis identified higher economic status as a risk for VKC (OR = 1.4, P = 0.005). The effect on VKC of higher economic status appears not to act through differences in parasitic intestinal load.

Evaluation of fluticasone propionate and fluticasone propionate/salmeterol combination on exercise in pediatric and adolescent patients with asthma

OBJECTIVE

This study was designed to demonstrate that four weeks of fluticasone propionate (FP) 100 micrograms (mcg) combined with salmeterol 50 mcg twice daily (BID) via DISKUS(®) resulted in protection against bronchospasm induced by activity, as measured by standardized exercise challenge testing in pediatric and adolescent subjects who required regular use of inhaled corticosteroids for the treatment of persistent asthma.

METHODS

Prior to study entry, all patients reported regular use of inhaled corticosteroids (ICS). During screening all patients demonstrated ≥20% fall in FEV(1) following exercise.

RESULTS

A total of 231 subjects aged 4 to 17 were randomized to the two study treatments: 113 to the FP/salmeterol combination group (FSC) and 118 to receive FP 100 mcg BID. Of the subjects randomized, 106 (94%) subjects in the FSC 100/50 group and 108 (92%) subjects in the FP 100 group completed the study. At the end of treatment (Week 4), both FSC and FP protected against a fall in FEV(1) following exercise in patients who at baseline experienced ≥20% fall in FEV(1) following exercise. A mean decrease in FEV(1) of 9.9% was observed in the FSC 100/50 group as compared with a mean decrease of 11.1% in the FP 100 group; there was no statistical difference between treatments.

CONCLUSION

Both FSC 100/50 and FP 100 provided protection against an exercised-induced fall in FEV(1); but statistically significant differences we not noted. Both treatments were well-tolerated over four weeks and FSC 100/50 had an adverse event profile comparable to that observed with FP 100.

Physical Activity in Childhood Asthma: Friend or Foe?

Physical activity has been considered as a double-edged sword for children with asthma. Children with asthma are recommended to participate in physical activities like their healthy nonasthmatic peers because regular physical activity positively affects psychological functioning, quality of life, morbidity, and aerobic fitness in children with asthma. However, uncontrolled asthma with ongoing exercise-induced bronchoconstriction may limit participation in sports, free play, and daily living. Observations also suggest that high-intensity exercise performed in cold air, seasonal allergens, pollutants, or respiratory virus infections may increase the risk for asthma in the highly active child. In contrast, a sedentary lifestyle has been highlighted as the explanation for the increased prevalence of asthma in the past decades. However, there is no consensus on whether a low level of physical activity increases the severity or risk of asthma. Use of asthma medications and good asthma control can make the conditions favorable for a physically active lifestyle and influence physical activity level and the level of aerobic fitness.

Exercise-induced asthma, respiratory and allergic disorders in elite athletes: epidemiology, mechanisms and diagnosis: part I of the report from the Joint Task Force of the European Respiratory Society (ERS) and the European Academy of Allergy and Clinical Immunology (EAACI) in cooperation with GA2LEN

AIMS

To analyze the changes in the prevalence of asthma, bronchial hyperresponsiveness (BHR) and allergies in elite athletes over the past years, to review the specific pathogenetic features of these conditions and to make recommendations for their diagnosis.

METHODS

The Task Force reviewed present literature by searching Medline up to November 2006 for relevant papers by the search words: asthma, bronchial responsiveness, EIB, athletes and sports. Sign criteria were used to assess level of evidence and grades of recommendation.

RESULTS

The problems of sports-related asthma and allergy are outlined. Epidemiological evidence for an increased prevalence of asthma and BHR among competitive athletes, especially in endurance sports, is provided. The mechanisms for development of asthma and bronchial hyperresponsiveness in athletes are outlined. Criteria are given for the diagnosis of asthma and exercise induced asthma in the athlete.

CONCLUSIONS

The prevalence of asthma and bronchial hyperresponsiveness is markedly increased in athletes, especially within endurance sports. Environmental factors often contribute. Recommendations for the diagnosis of asthma in athletes are outlined.

Diagnosis and treatment of asthma in childhood: a PRACTALL consensus report

Asthma is the leading chronic disease among children in most industrialized countries. However, the evidence base on specific aspects of pediatric asthma, including therapeutic strategies, is limited and no recent international guidelines have focused exclusively on pediatric asthma. As a result, the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology nominated expert teams to find a consensus to serve as a guideline for clinical practice in Europe as well as in North America. This consensus report recommends strategies that include pharmacological treatment, allergen and trigger avoidance and asthma education. The report is part of the PRACTALL initiative, which is endorsed by both academies.

Humidity influences exercise capacity in subjects with exercise-induced bronchoconstriction (EIB)

RATIONALE

Exercise-induced bronchoconstriction (EIB) increases in cold and dry air and decreases in humid air in subjects with asthma. Few reports have reported on the effect of humid environment upon exercise capacity in subjects with EIB.

OBJECTIVE

The primary aim of the present study was to examine the effect of changing the humidity of the environmental air upon exercise capacity measured by peak oxygen uptake (V O2 peak), peak ventilation (V Epeak) and peak running speed (V peak) and secondarily to assess the influence of environmental humidity upon EIB in subjects suffering from EIB.

METHODS

Twenty subjects (10-45 years old, male/female:13/7) with diagnosed EIB performed exercise testing under standardised, regular environmental conditions, 20.2 degrees C (+/- 1.1) and 40% (+/- 3.3) relative humidity [mean (+/- SD)], and under standardised humid environmental conditions; 19.9 degrees C (+/- 1.0) and 95% (+/- 1.7) relative humidity in random order on separate days. Lung function was measured before and 1, 3, 6, 10 and 15 min after exercise. Heart rate (HR), oxygen uptake (V O2), respiratory gas exchange ratio (RER), breathing frequency (BF) and minute ventilation (V E) were measured during exercise.

RESULTS

V O2 peak and V peak increased significantly from 40% to 95% relative humidity of the environmental air, 4.5% and 5.9%, respectively (P = 0.001). HRpeak increased significantly in the humid environment, while BF(peak) decreased significantly. RERpeak and V Epeak did not change significantly. Post-exercise reduction in FEV1 (DeltaFEV1) and FEF50 (forced expiratory flow at 50% of FVC) (DeltaFEF50) significantly decreased after exercise in a humid environment as compared to regular conditions, DeltaFEV1: 12% (7,17) vs. 24% (19,29) [mean (95% confidence intervals)], respectively, DeltaFEF50: 20% (12,29) vs. 38% (30,46), respectively (P < 0.001).

CONCLUSION

Exercise capacity (V O2 peak and V peak) markedly improved during exercise in humid air in subjects with EIB, whereas EIB was reduced to the half.

Asthma in medium altitude--exercise-induced bronchoconstriction in hypobaric environment in subjects with asthma

BACKGROUND

Hypoxic gas inhalation has been reported to enhance airway responsiveness and results in bronchoconstriction in animal models and in humans with asthma. However, the data have so far been conflicting. The aim of the present study was to examine the effect of reduced barometric pressure on exercise-induced bronchoconstriction (EIB) in subjects with asthma.

METHODS

Twenty subjects (10-45 years old, male symbol/female symbol = 13/7) with asthma (at least 10% reduction in forced expiratory volume in 1-second postexercise) participated in exercise testing in barometric pressure corresponding to altitudes of 200 (normobaric) and 2500 (hypobaric) m above sea level in random order on separate days. Lung function was measured before and after exercise, as well as after inhalation of salbutamol. Heart rate, oxygen uptake (), arterial oxygen saturation (S(p)O(2)), respiratory gas exchange ratio (RER) and minute ventilation () were measured during exercise.

RESULTS

There was no difference in lung function after exercise. The and HR(peak) during exercise did not differ. The RER(peak) was higher (P = 0.04) in hypobaric environment. The decreased 10.1% (7.2-13.0) [mean (95% confidence intervals)] (P < 0.001) from normobaric to hypobaric environment. At the same time, S(p)O(2) at decreased from 94.4 (92.2-96.6) to 85.6% (82.8-88.4) (P < 0.001).

CONCLUSIONS

A barometric pressure corresponding to altitude of 2500 m did not increase EIB in subjects with asthma. The reduction in is most probably due to the lower S(p)O(2) in hypobaric environment.

Broncoespasmo induzido pelo exercício em crianças e adolescentes com diagnóstico de asma

INTRODUÇÃO: A broncoconstrição temporária após o exercício físico tem elevada prevalência em crianças e adolescentes asmáticos. OBJETIVO: Determinar a freqüência e gravidade do broncoespasmo induzido pelo exercício em crianças e adolescentes, com diagnóstico clínico de asma leve, moderada e grave. MÉTODO: Foi realizado um estudo descritivo, tipo transversal, não controlado. A amostra constituiu-se de 40 indivíduos asmáticos, de ambos os sexos, com idade entre 7 e 18 anos, que não utilizavam regularmente medicação anti-inflamatória. Foi realizado teste padronizado de provocação brônquica com exercício de corrida em esteira rolante. A espirometria foi padronizada em seis manobras expiratórias, realizadas antes e aos 1, 5, 10, 15, 20 e 30 minutos após o término do exercício, sendo escolhida a de maior valor. O volume expiratório forçado no primeiro segundo (VEF1) foi utilizado para o diagnóstico e classificação da gravidade do broncoespasmo. Os pacientes asmáticos apresentavam condições clínicas e espirométricas adequadas para os testes (VEF1 > 70% do valor previsto). Foi utilizada como critério de positividade para o broncoespasmo induzido pelo exercício queda >10% em relação ao VEF1 prévio ao exercício. RESULTADOS: Vinte e seis (65%) pacientes desenvolveram broncoespasmo após o exercício. Dos pacientes com asma leve 44%, e dos com asma moderada e grave, 100% desenvolveram broncoespasmo. Houve associação significativa entre a freqüência do broncoespasmo induzido pelo exercício e a gravidade da asma (p< 0,05), e diferença significativa entre a sua gravidade (confirmada por uma queda no VEF1) e a gravidade da asma (p < 0,05). CONCLUSÃO: A freqüência e gravidade do broncoespasmo induzido pelo exercício estiveram relacionadas com a gravidade clínica da asma.

Exercise-induced asthma in children

Exercise-induced asthma (EIA) is a relatively common problem in children, but may not be recognized because children either do not report their symptoms, or avoid activities that cause it. Clarifying the diagnosis of EIA, in particular separating EIA from other causes of exertional dyspnea, is essential. Treating EIA in children is challenging because of the nature of their physical activities, which are often not planned, and may be prolonged. Keeping children active is an important goal to ensure healthy physical and social development. Many children with EIA are well managed with an inhaled short-acting beta(2)-adrenoceptor agonist before exercise or if symptoms develop. The approach to more troublesome EIA depends on whether the child has persistent asthma and requires better prevention, or the EIA is an isolated clinical problem. The options for treatment also depend on the timing, frequency, and duration of activity that induces EIA. Options include the addition of a cromone, a leukotriene modifier, an inhaled corticosteroid, or switching to use a long-acting beta(2)-adrenoceptor agonist. The use of warm-up exercises has been shown to be helpful by using the refractory period but is not practical for most children with EIA. A final consideration for successful management of EIA in children is that the delivery of medication needs to be age-appropriate.

Heparin inhibits hyperventilation-induced late-phase hyperreactivity in dogs

Inhalation of heparin attenuates hyperventilation-induced bronchoconstriction in humans and dogs. The purpose of this study was to determine whether heparin inhibits the late-phase response to hyperventilation, which is characterized by increased peripheral airway resistance (RP), eicosanoid mediator production, neutrophilic/ eosinophilic inflammation, and airway hyperreactivity (AHR) at 5 h after dry air challenge (DAC). Fiberoptic bronchoscopy was used to record RP and airway reactivity (DeltaRP) to aerosol and intravenous histamine before and 5 h after DAC. Bronchoalveolar lavage fluid (BALF) cells and eicosanoid mediators were also measured approximately 5 h after DAC. DAC of vehicle-treated bronchi resulted in late-phase airway obstruction (approximately 120% increase over baseline RP), inflammation, increased BALF concentrations of leukotriene (LT) C(4), LTD(4), and LTE(4) and prostaglandin (PG)D(2), and AHR. Pretreatment with aerosolized heparin attenuated late-phase airway obstruction by approximately 50%, inhibited eosinophil infiltration, reduced BALF concentrations of LTC(4), LTD(4), and LTE(4) and PGD(2), and abolished AHR. We conclude that heparin inhibits hyperventilation-induced late-phase changes in peripheral airway function, and does so in part via the inhibition of eosinophil migration and eicosanoid mediator production and release.

Exercise-induced bronchoconstriction among Malay schoolchildren

OBJECTIVE

Exercise-induced bronchoconstriction (EIB) may be demonstrated in 60-70% of asthmatic children in temperate climates. In areas of high humidity it is postulated to be low. The aim of the study was to determine the prevalence of EIB in a population of schoolchildren with wheezing, living in the humid tropical climate of Kuala Lumpur, Malaysia.

METHOD

We performed a cross-sectional study using the International Study of Asthma and Allergies in Childhood questionnaire to identify 7-12-year-old Malay children with asthma symptoms from a primary school in central Kuala Lumpur. Sixty-five of 76 children with 'ever wheeze' performed an exercise challenge test successfully in an uncontrolled environment. A random sample of 80 schoolchildren with no history of wheeze were similarly tested as controls. The relative humidity and temperature were recorded. A fall of > 15% was considered as clinically important.

RESULTS

The prevalence of EIB in schoolchildren with 'ever wheeze' was 47.7%. The prevalence of EIB in children with 'current wheeze' was 51.6%. The prevalence of EIB in controls was 7.5%. The relative humidity during the study ranged from 41 to 90%. There was no significant relationship between different humidity levels and EIB (P = 0.58, regression analysis).

CONCLUSION

This study demonstrates that EIB is present in asthmatic children despite the highly humid tropical environment.

Protection against cold air and exercise-induced bronchoconstriction while on regular treatment with Oxis

This study aimed to compare the duration of protection against exercise-induced bronchoconstriction (EIB) after inhalation of formoterol (Oxis) Turbuhaler with that of terbutaline Turbuhaler and placebo Turbuhaler in asthmatic patients treated regularly with formoterol Turbuhaler 9 microg b.i.d. and inhaled steroids. The study. performed at three centres (Göteborg and Lund, Sweden, and Trondheim, Norway), consisted of an open-label part with formoterol Turbuhaler 9 microg b.i.d. and a randomized, double-blind, cross-over part with a single dose (on top of the regular treatment) of either formoterol Turbuhaler 9 microg, terbutaline Turbuhaler 0.5 mg or placebo Turbuhaler. The patients attended the clinic six times: twice for screening visits, three times for randomized treatment and once for a follow-up visit. Patients received regular b.i.d. treatment with formoterol 9 microg for a mean period of 16 days. Formoterol gave a post-exercise fall of 12, 10, 15 and 17% in forced expiratory volume in 1 sec (FEV1) 15 min, 4, 8 and 12 h after inhalation. The differences compared with placebo (falls of 26, 22, 23 and 22%) and terbutaline (falls of 17, 18, 22 and 22%) were all statistically significant (P<0.05 for all comparisons). Patients on regular treatment with formoterol Turbuhaler 9 microg b.i.d. have a significant protection against EIB up to 12 h after inhalation of formoterol 9 microg. The protection was also significantly better than that of terbutaline Turbuhaler 0.5 mg.

Exercise-induced bronchoconstriction depends on exercise load

Exercise-induced bronchoconstriction (EIB) is often used as a measure of bronchial hyperresponsiveness and employed in epidemiological studies. Different tests are used, including free running tests with poor standardization of exercise load. The present study aimed to assess the role of exercise load in relationship to level of EIB.

METHODS

20 asthmatic children, 9-17 years old with a history of EIB, underwent two treadmill test with 85% and 95% exercise load. The children ran with increasing speed for the first 2 min until reaching a heart rate of 85% or 95% of calculated maximum (220-age) and maintained this speed for the last 4 min. Lung function was measured before running, and 0, 3, 6, 10 and 15 min after the run. Borg scale for perceived exertion was employed for children's self-evaluation of exercise load.

RESULTS

Peak heart rate, mean Borg score during 85% exercise load was 178.7/13.6 and during 95% was 194.3/18.2 (P<0.001). Maximum fall in FEV1 after 85% exercise load was 8.84% vs. 25.11% after 95% (P<0.001). Nine subjects (40%) fell > or = 10% in FEV1 after 85% exercise load vs. 20 subjects (100%) after 95% exercise load. EIB from the 95% exercise load test had markedly higher correlation with serum ECP (r=0.77, P<0.001).

CONCLUSION

Exercise load is essential for the interpretation of EIB, and strict standardization of exercise tests should be undertaken. The EIB from the high exercise load tests seemed better correlated to inflammatory activity than the low exercise load test.

Formoterol via Turbuhaler gave better protection than terbutaline against repeated exercise challenge for up to 12 hours in children and adolescents

We aimed to compare the protective effect of single doses of 4.5 and 9 microg of formoterol fumarate (F), 0.5 mg terbutaline sulphate (T) and placebo (P), all via Turbuhaler, against exercise-induced bronchoconstriction (EIB) in children. Twenty-seven asthmatic children, showing a fall of > or =20% in FEV1 after a standardized exercise challenge test (ECT) combined with cold air (-10 degrees C) inhalation, were randomized in this cross-over, double-blind study. They had a mean age of 12.6 years (range 8-17 years), mean baseline FEV1 90% (73.9-105.6%) of predicted normal value. Seventeen children used inhaled glucocorticosteroids (120-750 microg day(-1)). ECTs were performed 15 min and 4, 8, and 12 h after drug administration. F significantly reduced the fall in FEV1 after ECT to 5.4% (15 min), 5.2% (4 h), 8.2% (8 h) and 9.3% (12 h) after 4.5 microg, and 2.5%, 3.0%, 5.0% and 5.4% after 9 microg, compared with a fall of 18.4%, 15.7%, 15.6% and 16.5% in FEV1 after P. The fall after T was 3.3%, 11.6%, 14.4% and 19.1% after 15 min, 4, 8 and 12 h respectively. The difference between F and T was statistically significant from 4 h and onward (P-value for all comparisons < 0.05). Children using a single dose of either formoterol Turbuhaler 4.5 or 9 microg had significantly better bronchoprotection against repeated exercise challenge up to 12 h compared with placebo and from 4 h onward compared with terbutaline Turbuhaler 0.5 mg.

Heparin inhibits eicosanoid metabolism and hyperventilation-induced bronchoconstriction in dogs

Inhalation of heparin, an anticoagulant, attenuates exercise- induced asthma (EIA) in human subjects. The purpose of this study was to determine if heparin inhibits hyperventilation-induced bronchoconstriction (HIB) in a canine model of EIA, and if its mode of action involves the inhibition of eicosanoid mediator production and release. We used a wedged bronchoscope technique to measure baseline peripheral airway resistance (Rp). We then performed either a 2-min or 5-min dry air challenge (DAC) by temporarily increasing from 200 to 2,000 ml/min the flow of 5% CO(2) in air used to ventilate a wedged sublobar segment. We compared HIB before and 60 min after aerosol treatment with either bacteriostatic water (BW) or heparin. We found that (1) heparin had no effect on baseline Rp, (2) BW did not alter the response to DAC, and (3) heparin reduced HIB by approximately 50-60%. On the basis of bronchoalveolar lavage fluid (BALF) cell analysis, heparin and BW caused acute infiltration of macrophages and eosinophils, and heparin increased the number of erythrocytes recovered immediately after DAC. Despite these acute inflammatory effects initiated prior to DAC, BALF mediator analyses revealed that pretreatment with heparin either attenuated or abolished hyperventilation-induced leukotriene, prostaglandin, and thromboxane release. Thus, our data provide direct evidence that inhaled heparin inhibits eicosanoid mediator production and release caused by hyperventilation with dry air, and significantly attenuates HIB.

Low-dose budesonide improves exercise-induced bronchospasm in schoolchildren

The aim of this study was to compare the clinical efficacy of low-dose inhaled budesonide (once or twice daily) and placebo, administered via Turbuhaler, on exercise-induced bronchoconstriction (EIB) in children with mild asthma. Fifty-seven steroid-naive children (7-16 years old; 41 boys, 16 girls) with EIB participated in this sub-population study according to the following inclusion criterion: a maximum fall in forced expiratory volume in 1 s (FEV1) > or = 10% after a standardized treadmill test. Mean baseline FEV1 was 100.3% of predicted, and mean maximum fall in FEV1 after the standardized exercise test was 22%. The study was a double-blind, randomized, parallel-group design. After 2 weeks of run-in, the children received inhaled budesonide 100 microg or 200 microg once daily in the morning, 100 microg twice daily, or placebo, for 12 weeks. After 12 weeks of treatment, the fall in FEV1 after the exercise test was significantly less in all three budesonide groups (7.2-7.8%) vs. placebo (16.7%). Daytime symptom scores were significantly lower in all three budesonide groups compared with placebo (p <0.02). The three budesonide groups did not differ significantly, and no significant change in lung function was found in any group. Therefore children with mild asthma, but with significant EIB, improved their exercise tolerance and symptom control after 3 months of treatment with a low dose of inhaled budesonide given once or twice daily.

Combination drug therapy for the prevention of exercise-induced bronchoconstriction in children

BACKGROUND

Sequential administration of a beta-agonist and cromolyn or nedocromil before exercise is recommended for patients whose symptoms are not controlled by beta-agonists alone; however, this practice reduces compliance.

OBJECTIVE

To evaluate the effectiveness of a new pre-combined aerosol formulation (salbutamol and nedocromil) in preventing exercise-induced bronchoconstriction and to compare it to salbutamol alone.

METHODS

Twelve children with asthma were studied in a double-blind, double-dummy, randomized, crossover, placebo-controlled design to compare the protective effect of salbutamol and a new pre-combined salbutamol/nedocromil formulation against exercise-induced bronchoconstriction. The drugs were delivered by a metered-dose inhaler (salbutamol, 200 microg; salbutamol/nedocromil, 200 microg/4 mg; placebo, 2 puffs) 20 minutes before exercise.

RESULTS

Both active drugs were significantly more protective than placebo but there was no difference between them. Complete protection was obtained in 12/12, 10/12, and 1/12 subjects for the salbutamol/nedocromil combination, salbutamol alone and placebo, respectively.

CONCLUSIONS

Although inhaled beta-agonists alone are highly efficacious in preventing exercise-induced bronchoconstriction, a minority of patients exists for whom a combined treatment with salbutamol and nedocromil is advantageous. This group may represent a subpopulation of subjects who release more, or different, mediators in response to exercise.

Cold air inhalation and exercise-induced bronchoconstriction in relationship to metacholine bronchial responsiveness: different patterns in asthmatic children and children with other chronic lung diseases

Cold air inhalation and exercise-induced bronchoconstriction (EIB) have both been used as measures of bronchial responsiveness. Both stimuli are often combined in the Nordic climate. The main objective of the present study was to investigate the climatic influence of cold temperatures upon exercise-induced asthma. The secondary aims were: (a) to assess metacholine bronchial hyper-responsiveness and EIB in children with bronchial asthma (n = 32; mean age 10.8 years) compared to children with other chronic lung diseases (CLD) (n = 26, mean age 10.1 years); and (b) to assess the influence of cold air inhalation upon EIB in the two groups of children. Methods used were: (a) the metacholine concentration causing a reduction in FEV1 of 20% (PC20-M), (b) maximum FEV1 fall (delta FEV1) after submaximal treadmill run (EIB test); and (c) delta FEV1 after submaximal treadmill run while inhaling cold (-20 degrees C) dry air (CA-EIB test). Geometric mean PC20-M did not differ significantly between the asthma children (1.28 mg ml-1) and the CLD children (2.90 mg ml-1). In the asthma children, mean delta FEV1 after EIB test was 12.8% vs 21.8% after adding cold air (P < 0.0001), compared to 5.2 and 7.4%, respectively (P = 0.03), in the CLD group. Maximum sensitivity and specificity for the EIB test were 69.8% at a fall in FEV1 of 6.8%; for the CA-EIB test, 72% at a fall in FEV1 of 10.2%; and for metacholine provocation, 56% at a PC20-M of 1.5 mg ml-1. In conclusion, children with bronchial asthma are substantially more sensitive to cold air than children with CLD, and EIB is markedly increased by cold air inhalation in asthmatic children, maintaining the specificity of the EIB test and increasing the sensitivity. The low sensitivity of the EIB test is probably influenced by the use of inhaled steroids. Metacholine inhalation test has less specificity and sensitivity in discriminating asthma from other chronic lung diseases.

Differences in the effect of allergen avoidance on bronchial hyperresponsiveness as measured by methacholine, adenosine 5'-monophosphate, and exercise in asthmatic children

Asthma is now considered as an inflammatory airway disease. There is evidence that allergen avoidance reduces clinical symptoms in atopic asthma. We investigated the effect of a month's stay in the hypoallergenic environment of Davos, Switzerland (1560 m) which is relatively free of house dust mite (HDM) on changes in bronchial hyperresponsiveness (BHR), using the challenge tests of adenosine 5'-monophosphate (AMP), exercise and methacholine to test for BHR. Thirteen asthmatic children with an allergy to HDM participated in the study. We measured BHR on admission to the Davos Asthma Center and after 1 month in the house dust-free environment. The medications used by the patients at the time of admission were kept unchanged during this month. No significant difference in BHR was found to methacholine challenge after a 1-month stay at high altitude (P > 0.05). By contrast, the response to AMP was significantly different as indicated by displacement of the dose-response curve to the right by 2.15 doubling concentrations (P = 0.005). We also observed a significant difference in response to exercise (P = 0.03). These results indicate that a month's stay in a hypoallergenic environment caused a reduction in BHR to AMP and exercise, but not to methacholine. In addition, the results support the concept of differences in trigger mechanisms for BHR, and that responses to a methacholine challenge are not the same as responses to an exercise challenge. The observed reduction in BHR in asthmatic children to the indirect bronchial stimuli of AMP and exercise suggest reduced airway inflammation following avoidance of house dust aeroallergens. AMP and exercise challenges may therefore be better indicators of asthmatic airway inflammation than the direct stimulus of methacholine.

Eosinophils in exercise-induced asthma

The variations in serum levels of eosinophil cationic protein (ECP) have been measured after exercise challenge of 13 patients with asthma with exercise-induced asthma (EIA) and nine patients with asthma without EIA. The patients were treated before exercise in a randomized and blinded fashion with inhalation of one dose of either disodium chromoglycate, terbutaline, or budesonide and in an open study with 4 weeks of inhaled budesonide. In the group with EIA, there was, in some patients, an initial increase in serum levels of ECP after exercise, but 60 minutes after exercise, the levels were significantly reduced (p less than 0.001). Disodium chromoglycate and 4 weeks of budesonide treatment inhibited this reduction. Histamine challenge of the group with EIA produced a similar fall in serum ECP levels (p less than 0.001). The group without EIA had initially lower levels of ECP than the group with EIA (p less than 0.05 to p less than 0.01), and ECP stayed unaltered after exercise. The preexercise serum ECP levels correlated significantly to the maximal fall in peak expiratory flow in the untreated group (r = 0.91; p less than 0.001) and in the group receiving one dose of budesonide (r = 0.62; p less than 0.05). The blood eosinophil counts were unchanged after challenge and not related to lung function. The results suggest that the ECP content in serum reflects the degree of allergic inflammation in the lungs and thereby the degree of bronchial hyperreactivity.

Cooling-induced contraction of trachea isolated from normal and sensitized guinea-pigs

Fast (-7 degrees C/min) cooling of guinea-pig isolated trachea produced a rapidly developing, transient contraction followed by relaxation. Cooling-induced contraction was dependent on temperature (30, 20 or 10 degrees C) and responses in trachea obtained from actively sensitized guinea pigs were significantly greater (20 and 10 degrees C) than those observed in normal trachea. Cooling to 20 degrees C was selected for subsequent experiments. Pretreatment with sufficient concentrations of atropine, clemastine, cromoglycate, indomethacin, or nordihydroguaiaretic acid did not depress contraction to cooling in either normal or sensitized trachea. This indicates a direct effect of cooling. The contraction produced by cooling was resistant to verapamil (1 mumol/l) or dantrolene (0.3 mmol/l). Calmodulin antagonists (trifluoperazine, W-7 and calmidazolium; all of them at 10-100 mumol/l) inhibited contraction in sensitized and normal trachea. Activators of protein kinase C (phorbol 12,13-diacetate, 1 mumol/l) enhanced while inhibitors (H-7, 20 mumol/l; staurosporine, 10 mumol/l) depressed cooling-induced contraction in both normal and sensitized tissues. Incubation (20 min) in a Ca(2+)-free solution inhibited cooling-induced contraction in normal but not in sensitized trachea. Exposure to a low Na+ (25 mmol/l) or a K(+)-free medium abolished contraction to cooling in normal and sensitized trachea. Ouabain (0.1-10 mumol/l) and vanadate (0.01-5 mmol/l) inhibited cooling-induced contraction to a greater extent in normal than in sensitized trachea. Polymyxin B (0.5 mmol/l) selectively depressed responses to cooling in sensitized trachea. In a separate series of experiments, it was shown that sensitized trachea was hyperresponsive to ouabain and vanadate. Previous cooling to 20 degrees C abolished responses to ouabain but only attenuated those to vanadate.(ABSTRACT TRUNCATED AT 250 WORDS)

Cold air challenge of airway reactivity in children: a correlation of transcutaneously measured oxygen tension and conventional lung functions

For pharmacological challenges, a correlation between the induced changes of the transcutaneously measured oxygen tension (PtcO2) and of conventional pulmonary function tests (PFTs) has been documented. We performed a 4-minute cold air challenge (CACh) in 17 children with bronchial asthma under continuous monitoring of PtcO2, and correlated observed changes with CACh-induced alterations of conventional PFTs. PtcO2 decreased significantly with CACh (from 86 +/- 10 mmHg to 66 +/- 14 mmHg, P less than 0.001), but returned to near-baseline within the next 30 minutes. PFTs changed with a similar pattern; the closest correlation was found between the CACh-induced fall of PtcO2 and Delta-FEV1 (r = 0.833, P less than 0.001). Changes of FVC, PEF, and Vmax50 correlated significantly as well. PtcO2 can complement or substitute for conventional PFTs in assessing the response to CACh in children.

Cold air challenge for measuring airway reactivity in children: lack of a late asthmatic reaction

Cold air challenge (CACh) for measuring airway reactivity uses respiratory heat or water loss as a bronchoconstrictor stimulus; this stimulus is also important for the development of exercise-induced asthma, for which late asthmatic reactions (LARs) have been described. At 1200 hr on day 1, 22 children with asthma started to record their peak expiratory flow rate (PEFR) in 3 hr intervals until 0900 hr on day 2. At 1000 hr, they underwent a standardized 4 min CACh. Children then inhaled salbutamol and continued to record PEFR until 0900 hr on day 3. As a bronchodilator effect, PEFR measurements were significantly higher 2, 5, and 8 hr after CACh, but subsequently did not differ significantly from pre-CACh values. At 5 hr after CACh, individual values ranged from 95 to 137% of the corresponding pre-CACh measurements, at 8 hr from 94 to 150%, and at 11 hr from 80 to 121%. This random sample of children with asthma demonstrated no LAR after CACh.

Breathing pattern affects respiratory heat loss but not bronchoconstrictor response in asthma

To determine whether changes in breathing pattern alone affect respiratory heat loss (RHL) and the constrictor response to cold dry gas hyperpnea in asthmatic subjects, we performed the following 2 part study: first we measured RHL in 8 asthmatic and 8 normal subjects during controlled eucapnic hyperpnea while they breathed at inspiratory to expiratory ratios (I/E) of 1:3, 3:1, and 2:2, and we recorded postchallenge forced expiratory volume in 1 sec (FEV1) in the asthmatic group; we then performed the same measurements in 8 asthmatic and 8 normal subjects at fixed target minute ventilation (VE) for tidal volumes of 0.2 X Forced vital capacity (FVC), 0.4 X FVC, and 0.6 X FVC by varying the target respiratory rate appropriately. Our results show that (1) increasing I/E ratio or tidal volume-frequency ratio (VT/f) at fixed VE produced small but statistically significant increases (p less than 0.05) in overall heat loss per unit volume of respired gas (RHL/VE) in both asthmatic and nonasthmatic subjects of 1-4 cal/L; (2) changes in breathing pattern alone did not affect bronchoconstrictor response as assessed by lack of change in slopes and intercepts of % delta FEV1 vs. RHL dose-response curves; and (3) the increase in RHL per unit volume of respired gas resulting from increasing VT/f ratios during cold gas hyperpnea was significantly greater in asthmatic than in nonasthmatic subjects. We conclude that changes in breathing pattern may affect overall RHL measured at the mouth, although the maximum effect of such changes in both asthmatic and nonasthmatic subjects is small (10-15%); that such changes do not significantly alter airway constrictor response in asthmatic persons; and (3) that the effects of changing breathing pattern on RHL may be more pronounced in asthmatic than nonasthmatic subjects, which suggests that the asthmatic group may be less able to adapt to factors that alter the magnitude and site of RHL.

Exercise-induced asthma and the generation of neutrophil chemotactic activity

Heat-stable neutrophil chemotactic activity (HS NCA) has been demonstrated in serum of subjects with asthma after exercise and after allergen inhalation challenge. Heat-labile neutrophil chemotactic activity (HL NCA) has been investigated only after allergen inhalation challenge. In this study, we have measured HS NCA and HL NCA after exercise of 22 adult patients with asthma, 13 of whom had exercise-induced asthma (EIA). In the 13 patients, the effect of pharmacologic pretreatment on the generation of HS NCA and EIA was evaluated in a double-blind study with inhalation of either disodium cromoglycate, terbutaline, or budesonide 15 minutes before exercise. Additionally, the effect of 4 weeks of treatment with budesonide aerosol was evaluated in an open study. A significant increase (p less than 0.01) in HS NCA was found in the patients with EIA with peak activities 15 minutes after exercise. In patients without EIA, the activity of HS NCA was variable. No HL NCA was detectable after exercise. EIA was inhibited by disodium chromoglycate, terbutaline, and 4 weeks of treatment with budesonide. The generation of HS NCA was more or less inhibited by all three drugs with 4 weeks of treatment with budesonide as the most potent regimen. No late-phase asthmatic reactions to exercise were found. It is concluded that only HS NCA is generated after exercise of subjects with asthma and that this production is controlled by antiasthmatic drugs. However, the generation of HS NCA occurs irrespective of EIA.

Bronchial responsiveness to exercise after human cardiopulmonary transplantation

Heart-lung transplant (HLT) recipients characteristically display marked bronchial hyperresponsiveness (BHR) to inhaled methacholine, but their bronchial responsiveness (BR) to exercise has not been reported. We measured BR to exercise in 13 stable HLT recipients, 13 normal control (NC) subjects and 13 asthmatic patients (AS). All subjects exercised for eight minutes on a bicycle ergometer at a work level designed to obtain and maintain 80 percent maximum heart rate, or to tolerance. The postexercise fall in FEV1 was equivalent in the HLT group and the NC group (0 +/- 0.2 L vs 0 +/- 0.2 L:p = NS) in contrast to the AS group (-0.6 +/- 0.5 L:p less than 0.01). Stable HLT recipients do not exhibit BHR to exercise at tolerable work loads. This observation supports the hypothesis that BHR to methacholine after HLT is due to denervation hypersensitivity of muscarinic receptors rather than other causes.

Circulating concentrations of histamine, neutrophil chemotactic activity, and catecholamines during the refractory period in exercise-induced asthma

Circulating mediators and catecholamine concentrations have been measured in eight subjects with asthma who were subjected to two bouts of cycle ergometer exercise separated by 1 hour. The maximum falls in FEV1 were 21.9 +/- 2.3% (mean +/- SEM; n = 8) and 5.5 +/- 1.3% (mean +/- SEM; n = 8) after the first and second exercises, respectively. Serum neutrophil chemotactic activity (NCA) and plasma histamine and catecholamine levels in venous blood were measured with a microchemotaxis and two radioenzymatic techniques, respectively. There was a significant increase in NCA and plasma histamine concentrations after both exercise challenges, and there was no significant difference in the release of these mediators between the two exercise tests. Gel filtration chromatography demonstrated that the NCA detected after the first and second exercise tests had molecular sizes of approximately 600,000 daltons. There was no significant time-dependent increase in plasma norepinephrine and epinephrine concentrations after either exercise task, even though the patients were refractory to exercise-induced asthma after the second exercise. These results suggest that the refractory period in exercise-induced asthma is not caused by mediator depletion, as indicated by NCA and histamine measurements, or by protection of the airways through catecholamine release.

Ipratropium bromide in asthma. A review of the literature

In comparative studies of asthma, ipratropium bromide has been shown to have a slower onset of bronchodilator action but a longer duration of effect than beta agonists. An additive effect of ipratropium and beta agonists has been demonstrated, in addition to prolongation of the bronchodilator response. Most studies do not show a definite difference in responsiveness of atopic versus nonatopic asthmatic patients; there are, however, reports indicating a greater responsiveness to anticholinergic agents than to beta agonists in patients with chronic bronchitis and emphysema. Ipratropium has been shown not to affect mucociliary clearance, sputum volume, or viscosity. It effectively inhibits the bronchial response to methacholine and, to a lesser degree, to histamine, serotonin, bradykinin, and antigen. Protection against exercise-induced asthma with this drug has been variable, but ipratropium has been found particularly useful in psychogenic asthma. Its role in occupational asthma remains to be determined.