[The relation between the perception of dyspnea and beta 2-agonists consumption in patients with mild-moderate asthma].

It is well documented that, in patients with asthma, there is a considerable variation in the severity of breathlessness for any particular degree of airflow obstruction. The factors underlying this variability are still to be explored. The consumption of beta 2-agonists and the perception of dyspnea were assessed in eighty asthmatic patients, with mild-moderate asthma, attending the asthma clinic. The perception of dyspnea was compared to sixty normal subjects. All patients received treatment with inhaled corticosteroid and beta 2-agonists as needed. Nine patients were excluded from the study, hence the data reported relates to 71 patients. In 55% of the patients the mean score of the perception of dyspnea during breathing against resistance was normal, it was low in 20 (28%) and high in the remaining 12 (17%). There was no correlation between the FEV1 and the perception of dyspnea. The mean +/- SEM beta 2-agonists consumption was 2.9 +/- 0.4 puffs/day (range 0-7.2). There was a statistically significant difference in beta 2-agonists consumption between the mid asthmatic and the moderate asthmatic groups (p < 0.01). In both groups the mean beta 2-agonists consumption was significantly higher in the high preception of dyspnea group than in the normal (p < 0.05) and the low (p < 0.01) perception of dyspnea groups. We conclude that about half of mild-moderate asthmatic patients have normal perception of dyspnea while the other half have either high or low perception of dyspnea. More obstructed patients have higher beta 2-agonists consumption. However, in every degree of severity there is a close relation between the perception of dyspnea and the beta 2-agonists consumption.