Anxiety disorder and perception of inspiratory resistive loads

Sensations of breathlessness in the absence of respiratory disease are common in anxiety disorders. Perceptions of breathlessness in eight patients with anxiety disorder were compared with eight normal control subjects, matched for age and sex, by the application of Steven's law to the magnitude of resistive load test. All subjects estimated the magnitudes of resistive loads to inspiration while peak inspiratory mouth pressures were monitored. Anxious patients' perceptions of the added loads were significantly less sensitive than normal, even though the effort, determined by peak inspiratory mouth pressure, in overcoming each load was normal. Correlations between estimates of resistive loads and peak inspiratory mouth pressure were significantly less for the anxious patients than for normal subjects. Thus, perception of breathlessness in anxiety disorders may be affected by factors not normally associated with breathlessness and may help account for the greater than normal variability in resistive load perception in respiratory disease.