Exercise-induced asthma

Exercise-induced asthma (EIA) is common in asthmatic children and adolescents. Since it may cause limitations to daily life activities in up to 30%, mastering EIA is important in asthma management. EIA consists of bronchial obstruction occurring immediately, or soon after, physical exercise as a result of increased respiratory water and heat loss due to increased ventilation during exercise, with the subsequent release of mediators and stimulation of airways receptors. Diagnosis is best made by standardised exercise tests, preferably running on a treadmill for 6-8 minutes at an exercise load of 95% of maximum. The sensitivity of the test may be increased by cold air inhalation. EIA is best treated by inhaled steroids in addition to pre-treatment before exercise by inhaled beta(2)-agonists, short or long acting, and/or leukotriene antagonists. Physical training may improve physical fitness and quality of life in asthmatic children but baseline lung function and bronchial responsiveness are not improved.     

Bronchial hyperresponsiveness decreases through childhood

Limited knowledge exists about development of bronchial hyperresponsiveness (BHR) through adolescence. We aimed to assess changes in and risk factors for BHR in adolescence. From a Norwegian birth cohort 517 subjects underwent clinical examinations, structured interviews and methacholine challenges at age 10 and 16. BHR was divided into four categories: no BHR (cumulative methacholine dose required to reduce FEV(1) by 20% (PD(20)) >16 μmol), borderline BHR (PD(20) ≤16 and >8 μmol), mild to moderate BHR (PD(20) ≤8 and >1 μmol), and severe BHR (PD(20) ≤ 1 μmol). Logistic regression analysis was used to assess risk factors and possible confounders. The number of children with PD(20) ≤ 8 decreased from 172 (33%) to 79 (15%) from age 10-16 (p < 0.001). Most children (n = 295, 57%) remained in the same BHR (category) from age 10-16 (50% with no BHR), whereas the majority 182 (82%) of the 222 children who changed BHR category, had decreased severity at age 16. PD(20) ≤ 8 at age 10 was the major risk factor for PD(20) ≤ 8 6 years later (odds ratio 6.3), without significant confounding effect (>25% change) of gender, active rhinitis, active asthma, height, FEV(1)/FVC, or allergic sensitization. BHR decreased overall in severity through adolescence, was stable for the majority of children and only a minority (8%) had increased BHR from age 10 to 16. Mild to moderate and severe BHR at age 10 were major risk factors for PD(20) ≤ 8 at 16 years and not modified by asthma or body size.     

Respiratory effects of tobacco smoking on infants and young children

Second-hand smoke (SHS) and tobacco smoke products (TSPs) are recognised global risks for human health. The present article reviews the causal role of SHS and TSPs for respiratory disorders in infants and young children. Several studies have shown an effect of TSPs exposure during pregnancy upon lung function in the newborn infant and of SHS on symptoms and lung function after birth. From 1997 to 1999 a set of systematic reviews concerning the relationship between second-hand exposure to tobacco smoke and respiratory health in children was published in Thorax by Cook and Strachan, covering hundreds of published papers. The evidence for a causal relationship between SHS exposure and asthmatic symptoms and reduced lung function is quite strong, whereas the evidence related to the development of allergy is much weaker. There is recent evidence relating to an interaction between TSP exposure and genetic ploymorphisms, demonstrating that certain individuals are more susceptible to the effect of TSP exposure on lung health. In the present review, an overview is given for the effects of TSP exposure and SHS upon lung health in children, with a focus on infants and young children. There is a need for intervention to reduce TSP exposure in young children, by educating parents and adolescents about the health effects of TSP exposure. Recent legislation in many European countries related to smoking in the workplace is of great importance for exposure during pregnancy. Studies are needed to identify possible critical periods for TSPs to induce harmful effects upon lung health in young children and on environment-gene interactions in order to prevent harm.     

Pharmaceutical treatment of asthma in children

The present review article gives an overview of the present treatment modalities of asthma during childhood and discusses the existing controversies in asthma treatment. Present guidelines of asthma treatment concentrate on treatment for adults and only marginally concern treatment of childhood asthma. The few exceptions are the British Scottish guidelines and the Nordic guidelines, which have separate paragraphs on paediatric asthma management. The main controversy in paediatric asthma treatment is that how early (in age) and how soon (after diagnosis of asthma has been established) should inhaled steroids be instituted. Does treatment with early inhaled steroids influence lung development? Also possible side effects of inhaled steroids as possible impact upon growth and effect upon the hypothalamic adrenal axis are discussed. What is the place of leukotriene antagonists in childhood asthma treatment? Other issues discussed are prevention of asthma (primary, secondary and tertiary) in relationship to treatment of asthma. Primary prevention regards preventive measures to be taken to prevent initial allergic diseases; secondary prevention aims at preventing development of further allergic disease after the initial allergic disorder, as preventing debut of asthma after atopic eczema. Tertiary prevention aims at reducing already existing allergic illness and preventing further progression. For asthma, tertiary prevention regards treatment. During later years, there has been a focus on the respiratory tract as a continuum, and how allergic rhinitis and asthma should be treated when they are coexistent. Treating exercise induced asthma optimally is regarded as an important aim in the general treatment of asthma in childhood. Particularly in childhood asthma, compliance (concordance) with treatment is an important issue. Also some controversial aspects of acute asthma treatment in young children are discussed.     

The effect of formoterol inhalation on endurance performance in hypobaric conditions

INTRODUCTION: Inhaled beta2-agonists are important therapeutic agents for the treatment of exercise-induced asthma in athletes but are restricted by international antidoping regulations. PURPOSE: To investigate whether 18 mug of inhaled formoterol affects endurance performance during running at high altitudes until exhaustion among 20 nonasthmatic male athletes aged 21-35 yr. METHODS:: In a randomized, double-blind, placebo-controlled crossover study, the athletes performed one screening test and two similar performance tests. Each performance test consisted of 20 min of warm-up and a running test until exhaustion, which lasted 210-300 s in hypobaric conditions equal to 2000 m above sea level. Maximal oxygen consumption (VO2max) and peak ventilation (VEpeak) were measured during running, and pulmonary function was measured before and after exercise. The screening test was used to determine running speed on days 2 and 3, with inhaled formoterol or placebo in a randomized manner before exercise. VO2, VE, arterial oxyhemoglobin saturation (SPO2), and heart rate (HR) were measured during exercise, and maximum plasma lactate concentration was measured after exercise. RESULTS: Inhaled formoterol did not improve running time to exhaustion, VO2, VE, SPO2, or HR (P > 0.05) in hypobaric conditions compared with placebo, although formoterol significantly improved lung function (FEV1 and FEF50) 15 and 30 min before exercise and 3, 6, 10, and 15 min after exercise. CONCLUSIONS: Inhaled formoterol did not improve endurance performance in healthy nonasthmatic athletes at hypobaric conditions equal to 2000 m above sea level. Inhaled formoterol can thus be used by asthmatic athletes in sports under extreme conditions.     

Therapeutic strategies for allergic airways diseases

Asthma and allergic rhinitis are airways allergic diseases and different aspects of these diseases are discussed in this paper. Both diseases require specific treatment but the airways are a continuum and it has been shown that concomitant treatment in patients suffering from both diseases has a better effect than treating only one of the diseases. Furthermore, treatment of allergic rhinitis in asthmatic patients reduces the risk of hospital admission due to asthma and improves bronchial hyper-responsiveness. Anti-inflammatory therapy, particularly with local steroids, is the single most important treatment for airways allergic diseases. Some studies have shown the importance of starting early after diagnosing asthma but the issue of how early in life to start inhaled steroids is still being debated. Also leukotriene antagonists have been shown to have beneficial effects in many patients and can be used in conjunction with inhaled steroids. Combination therapy with inhaled steroids and inhaled beta(2)-agonists has been shown to be effective in adults but this has not yet been fully documented in children. Optimal treatment of exercise-induced asthma is important to enable children and adolescents to fulfill their developmental possibilities. Allergy vaccination has traditionally been used for treating airways allergic diseases. It is often given for allergic rhinitis when pharmacotherapy is not providing full symptom control. One recent study has suggested that allergy vaccination may possibly help to prevent the development of asthma in the child with allergic rhinitis. More research is needed on asthma allergy vaccination. Concordance with treatment may often be difficult and efforts should be taken to ensure the best concordance possible.