Chest
Volume 117, Issue 3, March 2000, Pages 722-727
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Clinical Investigations
ASTHMA
Specific Inspiratory Muscle Training in Patients With Mild Asthma With High Consumption of Inhaled β2-Agonists

https://doi.org/10.1378/chest.117.3.722Get rights and content

Background

It has been known for many years that there are variations between asthmatic patients in terms of their perception of breathlessness during airway obstruction.

Study objective

To investigate the relationship betweenβ 2-agonist consumption and the score of perception of dyspnea, in mild asthmatics, and the relationship between the effect of specific inspiratory muscle training (SIMT) on the score of perception of dyspnea and β2-agonist consumption in “high perceivers.”

Methods

Daily β2-agonist consumption was assessed during a 4-week run-in period in 82 patients with mild asthma. Patients with a mean β2-agonist consumption of > 1 puff/d (“high consumers”) then were randomized into two groups: one group of patients received SIMT for 3 months; the other group of patients was assigned as a control group and received sham training. Inspiratory muscle strength and perception of dyspnea were assessed before patients entered the study, following the 4-week run-in period, and after completing the training period.

Results

Following the 4-week run-in period, 23 high-consumer patients (mean [± SEM]β 2-agonist consumption, 2.7 ± 0.4 puffs/d) were detected. The mean Borg score during breathing against resistance was significantly higher (p < 0.05) in the patients with highβ 2-agonist consumption than in the subjects with low meanβ 2-agonist consumption. Following SIMT, the mean maximal inspiratory pressure increased significantly from 94.1 ± 5.1 to 109.7 ± 5.2 cm H2O (p < 0.005) in the training group. The increase in inspiratory muscle strength was associated with a statistically significant decrease in the mean Borg score during breathing against resistance (p < 0.05) as well as in the mean dailyβ 2-agonist consumption.

Conclusions

We have shown that patients with mild asthma, who have a highβ 2-agonist consumption, have a higher perception of dyspnea than those with normal consumption. In addition, SIMT was associated with a decrease in perception of dyspnea and a decrease inβ 2-agonist consumption.

Section snippets

Materials and Methods

Eighty-two patients, 46 men and 36 women, with mild, stable asthma (FEV1, > 80% of predicted normal values on at least two visits) attending an outpatient clinic were recruited for the study. All satisfied the American Thoracic Society definition of asthma, with symptoms of episodic wheezing, cough, and shortness of breath responding to bronchodilators and reversible airflow obstruction documented in at least one previous pulmonary function study.15 All subjects were in stable clinical

Results

Six patients had each recorded at least one decrease in the PEFR (to < 80% of their highest value) and were excluded from the study.

Following the 4-week run-in period, the remaining 76 subjects were separated into two groups: one group comprised 23 patients (15 men and 8 women) with a mean β2-agonist consumption of> 1 puff/d (defined as high consumers; mean ± SEM, 2.7 ± 0.4 puffs/d); the other group comprised 53 patients with a low meanβ 2-agonist consumption of ≤ 1 puff/d (mean± SEM, 0.4 ± 0.1

Discussion

In this study, we have shown that patients with mild asthma who are high β2-agonist consumers have higher perceptions of dyspnea than do normal consumers. In addition, SIMT was associated with a decrease in the perception of dyspnea in these high perceivers and a decrease in β2-agonist consumption. It is of interest that although the perception-of-dyspnea curve became similar to the curve of the normal consumers, the drop inβ 2-agonist consumption was, although significant, not to the level of

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