Exercise-induced asthma

Prevention of exercise-induced asthma by a natural isomer mixture of beta-carotene

BACKGROUND

The unicellular alga Dunaliella bardawil was previously shown to contain very high concentrations of beta-carotene composed of equal amounts of the all-trans and 9-cis stereoisomers which differ in their physicochemical features and antioxidative activity. Due to the controversy regarding the beneficial effect of antioxidants on asthma, the acute effects of beta-carotene of Dunaliella was assessed on airway hyperreactivity in patients with exercise-induced asthma (EIA).

METHODS

Thirty-eight patients with EIA participated in our study to verify the antioxidative effect. The test was based on the following sequence: baseline pulmonary function, 7 minutes exercise session on a motorized treadmill, 8 minutes rest, 1-week oral random, double-blind supplementation of placebo or 64 mg/day beta-carotene, pulmonary functions at rest, 7 minutes exercise session, 8 minutes rest and again pulmonary functions.

RESULTS

All patients given placebo showed a significant postexercise reduction of more than 15% in their forced expiratory volume in one second (FEV1). Of the 38 patients who received a daily dose of 64 mg of beta-carotene for 1 week, 20 (53%) were protected against EIA.

CONCLUSIONS

Our results indicate that a daily dose of Dunaliella beta-carotene exerts a protective effect against EIA in some patients most probably through in vivo antioxidative effect.

Prevention of exercise induced asthma by inhaled salmeterol xinafoate

The effect of inhaled salmeterol xinafoate, a long acting beta 2 agonist, on exercise induced asthma was studied in a double blind, crossover, and placebo controlled trial. Thirteen asthmatic children with a fall of at least 15% in their forced expiratory volume in one second (FEV1) after a standard exercise test on a motorised treadmill, on separate days performed the same test 1, 5, and 9 hours after a single dose of 50 micrograms salmeterol or placebo. FEV1 was measured before treatment, and before and for 30 minutes after each exercise test. After placebo the number of children with exercise induced asthma was: 10 at 1 hour, 11 at 5 hours, and 12 at 9 hours. Salmeterol prevented exercise induced asthma in all 13 children studied, at 1, 5, and 9 hours. Mean maximum falls in FEV1 after exercise were at 1 hour: salmeterol 2.7% and placebo 24.6%, 5 hours: salmeterol 5.3% and placebo 22.7%; and 9 hours: salmeterol 3.4% and placebo 26.6%. After salmeterol the mean increase in FEV1 was 17.8% at 1 hour, 19.6% at 5 hours, and 19.2% at 9 hours. Inhaled salmeterol prevents exercise induced asthma and produces significant bronchodilatation for at least 9 hours.

A short exercise and living course for asthmatics

A 5-day, non-residential exercise and living course for children with asthma is described as a feature of a programme of outpatient physiotherapy. Eleven children undertaking such a course were compared with 10 asthmatic children in a control group. The subject group showed, in the short term at least, an improvement in bronchial lability, peak flow rates, nocturnal and daytime wheeze, and activity compared with the controls. These findings were statistically significant. There was no difference between the groups in the number of days on which extra medication was taken. A short, sharp course is of benefit physically, socially and psychologically to children with asthma.

Reproducibility of exercise-induced asthma in children

The reproducibility of exercise-induced asthma (EIA) was studied in children with perennial asthma, using treadmill exercise challenge tests repeated at mean intervals of 1 week (Group I, n = 20), 1 month (Group II, n = 20) and 1 year (group III, n = 18). The protocol was standardized with respect to intensity and duration of exercise, time of last medication prior to exercise, air humidity, use of corticosteroids, asthma attacks, and 6) pollen season. The mean percentage fall in peak expiratory flow (PEF) following exercise remained significantly unchanged in the three groups. The reproducibility of EIA was improved compared with previous studies. Although the random variation of EIA tended to be greater in Group III, the individual severity of EIA was remarkably stable whatever the interval between tests. Improvements in baseline airway function between tests were not followed by a simultaneous decrease in EIA. In conclusion, the severity of EIA is reproducible in children with perennial asthma, when the exercise protocol is standardized for factors known to influence bronchial reactivity.

A pilot study of the multidisciplinary management of childhood asthma in a family practice

A small, controlled trial of joint treatment of childhood asthma by a doctor, a physiotherapist, a psychologist, and a social worker, working together in the family setting, demonstrated an improvement in ventilatory capacity. The limited scope of this trial does not permit more general conclusions as to the effect of such treatment on the severity and frequency of attacks, but the observation that some measurable physiological improvement occurred suggests that the place of multidisciplinary nonpharmaceutical management of childhood asthma should be investigated in more detail.

The effects of pharmacological treatment on pulmonary function in children with exercise-induced asthma

The effects of two therapeutic regimens were investigated in eleven boys and eight girls (8--13 years) with a history of exercise-induced asthma (EIA), who reacted with subjective signs of EIA and a decrease in FEV1.0 exceeding 10% after an exercise test. A test program (TP) including complete spirometry, bicycle ergometer and treadmill exercise tests preceded and followed by dynamic spirometry at one and five min after exercise, was performed before and after each treatment period. In 12 patients with sporadic medication before the trials, continuous peroral treatment with a combination of a beta 2-stimulating drug and a xanthine derivative for three weeks did not significantly improve TP data. In 13 children (six from the above group) who were already on continuous treatment as above, addition of disodium cromoglycate (DSCG) inhalations for 3--4 weeks improved the response to acute administration of a beta-receptor stimulatory aerosol but did not influence EIA. Seven of the children continued their DSCG treatment for one year. Minor improvement of EIA provoked by cycling but not by treadmill was seen after this. The ventilatory effort in relation to working intensity was lowered. No significant differences were found between treadmill running and cycling in provoking asthma.

Do sympathomimetic amines prevent exercise-induced asthma by bronchodilatation alone?

Seventeen patients with exercise-induced asthma were studied. Eleven patients (cases 7-17), of whom seven were atopic subjects, were given isoetharine or isoprenaline and were subsequently tested for exercise-induced asthma after bronchodilatation had ceased. In two atopic and one non-atopic patients protection was observed which could not be attributed to chance. Two of these three patients were studied again and this phenomenon was repeatable. Prevention of exercise-induced asthma 30 min after inhalation of isoetherine and sodium cromoglycate was compared in 10 patients (cases 1-10), of whom six were atopic subjects. There was no significant difference in the results and protection from isoetharine was not related to the magnitude of its bronchodilator effect. These results suggest that beta-adrenergic agonists may have both bronchodilator and other actions in exercise-iduced asthma. Whether these other actions are anti-alergic is unknown.