Exercise-induced asthma in children

Assessing paediatric exercise-induced bronchoconstriction using electromyography

BACKGROUND

Asthma is one of the most common chronic diseases in childhood, occurring in up to 10% of all children. Exercise-induced bronchoconstriction (EIB) is indicative of uncontrolled asthma and can be assessed using an exercise challenge test (ECT). However, this test requires children to undergo demanding repetitive forced breathing manoeuvres. We aimed to study the electrical activity of the diaphragm using surface electromyography (EMG) as an alternative measure to assess EIB.

METHODS

Forty-two children suspected of EIB performed an ECT wearing a portable EMG amplifier. EIB was defined as a fall in FEV 1 of more than 13%. Children performed spirometry before exercise, and at 1, 3 and 6 min after exercise until the nadir FEV1 was attained and after the use of a bronchodilator. EMG measurements were obtained between spirometry measurements.

RESULTS

Twenty out of 42 children were diagnosed with EIB. EMG peak amplitudes measured at the diaphragm increased significantly more in children with EIB; 4.85 μV (1.82-7.84), compared to children without EIB; 0.20 μV (-0.10-0.54), (p<0.001) at the lowest FEV 1 post-exercise. Furthermore, the increase in EMG peak amplitude could accurately distinguish between EIB and non-EIB using a cut-off of 1.15 μV (sensitivity 95%, specificity 91%).

CONCLUSION

EMG measurements of the diaphragm are strongly related to the FEV1 and can accurately identify EIB. EMG measurements are a less invasive, effort-independent measure to assess EIB and could be an alternative when spirometry is not feasible.

Effect of Submaximal Warm-up Exercise on Exercise-induced Asthma in African School Children

BACKGROUND

Regular physical activity has long been regarded as an important component of a healthy lifestyle. Exercise-induced asthma (EIA) is one of the major problems interfering with the performance of exercise. A warm-up exercise programme has been cited as a non-pharmacologic means of reducing EIA, but its effect has not been fully elucidated.

OBJECTIVE

The aims of this study were to determine the prevalence of unrecognized EIA in Pretoria primary school children, determine the effect of a warm-up exercise programme on EIA and to establish the relationship between history of allergy, family history of asthma and EIA.

METHODS

A random sample of 640 school children was selected. The study was divided into three phases. In phase one, a descriptive cross-sectional study was done using the standardized European Community Respiratory Health Survey (ECRHS) questionnaire. In phase two, non-asthmatic participants that returned a completed questionnaire were included in the field study. Pre-test and post-test experimental designs were used, where peak expiratory flow rate (PEFR) was measured at baseline and within ten minutes after exercise. A total of 340 subjects completed the Free Running Asthma Screening Test (FRAST); EIA was defined as a decrease in baseline PEFR ≥ 10% after exercise and 75 children (22%) had EIA. In phase three, 29 of the 75 subjects participated in the warm-up programme which was performed in the laboratory and subjects acted as their own controls. Predefined protocols for the study were followed.

RESULTS

Seventy-five (22%) of the 340 participants had EIA. The mean age, height and weight were 10.51 years, 139.26 cm and 33.45 kg, respectively. Exercise-induced asthma symptoms were cough (25%), chest pain (16%), wheeze (12%) and chest tightness (12%). The history of allergy was 75%, family history of allergy 40% and positive history of allergy when near animals, feathers or in dusty areas 38%. Wheezing during or after exercise, wheezing when near animals, feathers or in dusty areas and chest pain was significant (p < 0.05). The mean PEFR after exercise without warm-up was 4.43 L/min. The mean PEFR after exercise (warm-up) was 4.98. The mean percentage change in PEFR between exercise without warm-up and exercise with warm-up was 14.83%. The paired t-test showed a significant difference between PEFR with warm-up and PEFR without warm-up (p < 0.05).

CONCLUSION

There was a high prevalence of EIA among study participants. Exercise-induced asthma symptoms were significant for wheezing and chest pain. Exercise after warm-up was significant in reducing EIA. This study reports the effect of warm-up exercise on EIA and highlights the need to screen school children for EIA.

Polycyclic aromatic hydrocarbons and childhood asthma

Asthma is the most common chronic illness in children living in developed countries and the leading cause of childhood hospitalization and school absenteeism. Prevalence rates of asthma are increasing and show disparities across gender, geographic regions, and ethnic/racial groups. Common risk factors for developing childhood asthma include exposure to tobacco smoke, previous allergic reactions, a family history of asthma, allergic rhinitis or eczema, living in an urban environment, obesity and lack of physical exercise, severe lower respiratory tract infections, and male gender. Asthma exacerbation in children can be triggered by a variety of factors, including allergens (e.g., pollen, dust mites, and animal dander), viral and bacterial infections, exercise, and exposure to airway irritants. Recent studies have shown that exposure to polycyclic aromatic hydrocarbons (PAHs), a major component of fine particulate matter from combustion sources, is also associated with onset of asthma, and increasing asthmatic symptoms. In this paper, we review sources of childhood PAH exposure and the association between airborne PAH exposure and childhood asthma prevalence and exacerbation.

A medication assessment tool to evaluate adherence to medication guideline in asthmatic children

OBJECTIVE

Asthma is one of the commonest causes of morbidity and mortality in childhood. The goals of the present study were to design a valid medication assessment tool for evaluating the quality of medication use according to recommendations of updated asthma guidelines for children aged from 5 to 12 years, and to quantify adherence to guideline recommendations.

SETTING

Two primary care settings in Scotland, UK.

METHODS

Recommendations related to the long-term management of asthmatic children in the British Thoracic Society/Scottish Intercollegiate Guidelines Network and Global Initiative for Asthma guidelines were identified and corresponding criteria were created. These criteria were incorporated to generate an assessment tool named MAT ASTHMA-PAED. Two phases of field-testing were undertaken and the tool was also subject to examination by a focus group of specialist practitioners. Thereafter, MAT ASTHMA-PAED was modified accordingly.

MAIN OUTCOME MEASURE

Applicability and adherence to each criterion and overall adherence to the MAT ASTHMA-PAED.

RESULTS

The MAT ASTHMA-PAED field-testing was undertaken in two primary care practices in Scotland, United Kingdom and 77 asthmatic children were recruited. Results of the pilot study field-testing showed a high overall adherence of 70.0 % (95 % CI: 58.7-81.3 %) to the guidelines. Low adherence (<50 %) was seen for 4 criteria, whereas 8 criteria were considered high-adherence criteria (>70 %). The final MAT ASTHMA-PAED comprised of 25 criteria was produced based on the results of field testing and the opinions from the focus group.

CONCLUSION

Although high utility of MAT ASTHMA-PAED criteria was found, there were gaps in the implementation of certain recommendations, particularly in relation to demonstrated satisfactory technique of inhaler. Moreover, further studies assessing the use of oral steroids and exercise-induced asthma, and wider implementation of MAT ASTHMA-PAED are required.

Management of exercise-induced bronchospasm in adolescents with asthma

Physical activity in persons with asthma is important at any age but even more so in adolescents. Collaboration between the nurse practitioner and adolescent is essential to develop an asthma management plan that will provide for optimal physical activity and prevent asthma exacerbations while exercising.

Single-dose agents in the prevention of exercise-induced asthma: a descriptive review

Exercise-induced asthma (EIA) refers to the transient narrowing of the airways that occurs after vigorous exercise in 50-60% of patients with asthma. The need to condition the air inspired during exercise causes water to be lost from the airway surface, and this is thought to cause the release of inflammatory mediators (histamine, leukotrienes, and prostaglandins) from mast cells. EIA is associated with airway inflammation and its severity is markedly reduced following treatment with inhaled corticosteroids. Drugs that inhibit the release of mediators and drugs that inhibit their contractile effects are the most successful in inhibiting EIA. Single doses of short-acting beta(2)-adrenoceptor agonists, given as aerosols immediately before exercise, are very effective in the majority of patients with asthma, providing about 80% protection for up to 2 hours. Long-acting beta(2)-adrenoceptor agonists (LABAs) given in single doses can be effective for up to 12 hours when used intermittently, but tolerance to the protective effect occurs if they are taken daily. Drugs such as cromolyn sodium (sodium cromoglicate) and nedocromil given as aerosols are less effective than beta(2)-adrenoceptor agonists (beta(2)-agonists), providing 50-60% protection for only 1-2 hours, but they have some advantages. They do not induce tolerance, the aerosol dosage can be easily titrated for the individual, and the protective effect is immediate. Because they cause no significant adverse effects, multiple doses can be used in a day. Leukotriene receptor antagonists, such as montelukast and zafirlukast, are also used for the prevention of EIA and provide 50-60% protection for up to 24 hours when given as tablets. Tolerance to the protective effect does not develop with regular use. If breakthrough EIA occurs, a beta(2)-agonist can be used effectively for rescue medication. For those patients with more persistent symptoms, the use of a LABA in combination with an inhaled corticosteroid has raised a number of issues with respect to the choice of prophylactic treatment for EIA. The most important issue is the development of tolerance to the protective effect of a LABA such that extra treatment may be needed in the middle of a treatment period. Recommending extra doses of a beta(2)-agonist to control EIA is not advisable on the basis that multiple doses can enhance the severity of EIA, delay spontaneous recovery from bronchoconstriction, and enhance responses to other contractile stimuli. It is time to take into account the advantages and disadvantages of the different drugs available to prevent EIA and to recognize that there are some myths related to their use in EIA.

Mast-cell stabilising agents to prevent exercise-induced bronchoconstriction

BACKGROUND

Exercise-induced bronchoconstriction (or asthma) following strenuous physical exertion is common and can cause sub-optimal performance, symptoms such as cough, dyspnea, wheeze, chest tightness, and can lead people to avoid physical activity. Management focuses on prevention with pre-exercise treatment using various pharmacologic agents. Mast cell stabilizing agents are effective in attenuating exercise-induced bronchoconstriction but their effectiveness compared to bronchodilator agents is unclear.

OBJECTIVES

To quantitatively compare the effects of inhaling a single dose of either mast cell stabiliser - nedocromil sodium or sodium cromoglycate - to a single dose of short acting beta-agonists or anti-cholinergic agents - atropine or ipratropium bromide - prior to a strenuous exercise challenge in participants with asthma who are at least 6 years of age and suffer from reproducible exercise-induced bronchoconstriction. The review also compares the effects between a short acting beta-agonist alone to a combination of a short acting beta-agonist + mast cell stabiliser.

SEARCH STRATEGY

We searched the Cochrane Airways Group ASTHMA and WHEEZ* trials register, Cochrane CENTRAL, Current Contents, review articles, textbooks and reference lists of articles. We also contacted the drug manufacturer and primary authors for additional citations.

SELECTION CRITERIA

Randomised trials comparing a single prophylactic dose of a mast cell stabiliser to a short acting beta-agonist, anti-cholinergic agent, or a short acting beta-agonist alone to a combination of short acting beta-agonist plus a mast cell stabiliser to prevent exercise-induced bronchoconstriction in asthmatics over six years old. The exercise challenge had to conform to acceptable standards and pulmonary function (PFT) reported as percent decrease from baseline of FEV1 or peak flow. Complete protection (maximum % fall PFT <15% post-exercise) and clinical protection (50% improvement over placebo effect) measures were included.

DATA COLLECTION AND ANALYSIS

Trial inclusion and quality assessments were conducted independently by two reviewers using standardised forms. A second reviewer confirmed data extraction and calculations. Attempts were made to contact study authors. The pooled estimate involving continuous pulmonary function measures are reported as a weighted mean difference (WMD), dichotomous data as an odds ratio (OR), both with 95% confidence intervals (95%CI) using a random effects model. Heterogeneity tests for pooled results were performed.

MAIN RESULTS

Twenty-four trials (518 participants) conducted in 13 countries between 1976 and 1998 were included. All drugs were effective at attenuating the exercise-induced bronchoconstriction response but to varying degrees even within the same individual. Compared to anti-cholinergic agents, mast cell stabilisers were somewhat more effective at attenuating bronchoconstriction. On average the maximum fall on MCS was reduced to 7.1% compared to 13.8% on AC ( WMD = 6.7%; 95% CI: 3.3 to 10.0), provided more individuals with complete protection (73% vs 56%; OR = 2.2; 95% CI: 1.3 to 3.7) and clinical protection (73% vs 52%; OR = 2.7; 95% CI: 1.1 to 6.4). There were no subgroup differences based on age, severity, or study quality, and no adverse effects were reported for either agent group. When compared to short acting beta-agonists mast cell stabilisers were not as effective at preventing deterioration. On average the maximum fall on MCS was 11.2% compared to 4.3% on beta agonists ( WMD = 6.8%; 95% CI: 4.5 to 9.2). MCS provided fewer individuals with complete protection (66% vs 85%; OR = 0.3; 95% CI: 0.2 to 0.5) or clinical protection (55% vs 77%; OR = 0.4; 95% CI: 0.2 to 0.8). There were no significant subgroup differences based on age, severity, drug, delivery, or study quality. A non-significant difference in side effects was demonstrated with 11% of short acting beta-agonist patients experiencing side effects compared to 3% of those receiving mast cell stabilisers (OR = 0.2; 95% CI: 0.0 to 8.2). Combining masta-agonist patients experiencing side effects compared to 3% of those receiving mast cell stabilisers (OR = 0.2; 95% CI: 0.0 to 8.2). Combining mast cell stabilisers with a short acting beta-agonist did not produce significant advantages to pulmonary function over short acting beta-agonists alone. On average the maximum fall on SABA only was reduced to 5.3% compared to 3.5% on the combination ( WMD = 1.8%; 95% CI: -1.1 to 4.6). Beta-agonists alone provided fewer individuals with complete protection (68% vs 80%; OR = 0.5; 95% CI: 0.2 to 1.4) or clinical protection (70% vs 86%; OR=0.4; 95% CI: 0.1 to 1.2) but the difference did not reach significance (p=0.17). There were no subgroup differences.

REVIEWER'S CONCLUSIONS

In a population of stable asthmatics short acting beta-agonists, mast cell stabilisers, or anticholinergics will provide a significant protective effect against exercise-induced bronchoconstriction with few adverse effects. On average, SABAs resulted in more effective attenuation than mast cell stabilisers, while mast cell stabilisers were more effective than anti-cholinergic agents. Combining SABA and mast cell stabilisers may be appropriate in selected cases. The variability in the individual degree of response to these drugs in multi arm trials suggests clinicians and patients work together to identify the most effective prophylactic therapy.