Objective: The perception of somatic sensations like dyspnea can be influenced by such factors as an individual s personality, experiences, or ability to adapt to stimuli. Our aim was to determine whether the perception of acute bronchoconstriction is different for patients with asthma and patients who have never experienced an episode of airway obstruction.
Patients and method: We studied 2 groups of patients. The first consisted of 24 subjects with intermittent rhinitis and asthma (10 females and 14 males) with a mean (SD) age of 25 (7) years. All reported not feeling dyspnea at rest on a Borg scale. The second group consisted of 24 subjects who only had rhinitis but no lung disease (no episode of asthma) or dyspnea at rest (12 females and 12 males) with a mean age of 27 (6) years. There were no significant differences between the groups with regard to sex, smoking, economic or educational level, anxiety (determined by the trait portion of the State-Trait Anxiety Inventory), depression (Beck Depression Inventory), or spirometric parameters. All took a histamine bronchial provocation test in which the patient assessed dyspnea on a modified Borg scale after each histamine dose. The provocation dose needed to produce a 20% decrease (PD20) in forced expiratory volume in the first second (FEV1) was calculated. We also recorded dyspnea perception score when FEV1 fell 5%, 10%, 15%, and 20%.
Results: No dyspnea was perceived at PS20 by 12.5% of the asthmatics and by 45% of nonasthmatics (P< .0001). The mean PS20 was 2.4 (2.1) (range, 0-7) in the first group and 0.37 (0.48) (range, 0-3) in the second (P< .0001). More asthma patients than nonasthmatics perceived dyspnea at all degrees of bronchial obstruction. PD20 was different in the 2 groups (1.6 [2] vs 6.03 [5] for the first and second groups, respectively; P< .003), but there was no significant relation between PD20 and PS20 (Spearman s correlation coefficient, 0.19; P= .221).
Conclusion: Our findings support the hypothesis that appropriate perception of dyspnea is grounded in prior experience and learning.