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