Recognition of added resistive loads in asthma: the importance of behavioral styles.

The wide range of recognition thresholds to added resistive loads previously observed in asthmatic patients was hypothesized to be at least partially dependent on psychologic factors. Therefore, we compared thresholds to added inspiratory and expiratory resistive loads obtained on each of 2 days for (1) 12 asthmatic and 12 normal subjects, while equating for behavioral styles related to anxiety and dependency, and (2) behavioral styles when the presence and absence of asthma was controlled. The threshold values for inspiration and expiration did not differ between asthmatic and normal subjects; on contrast, anxious, dependent subjects had significantly greater threshold values for inspiration and expiration than adaptive or rigidly independent subjects. Thresholds were unrelated to baseline airway resistance. In addition, inspiratory threshold was not reproducible across days of the study (r = 0.34, ns), and the expiratory threshold was only moderately reproducible across days (r = 0.48, p less than 0.05). There was a good relationship between inspiratory and expiratory threshold values within Day 1 (r = 0.68, p less than 0.001) and Day 2 (r = 0.69, p less than 0.001). The results suggest that behavioral style and time of testing are more important determinants of the recognition of added resistive loads than the presence or absence of asthma.