Psychological profile and ventilatory response to inspiratory resistive loading

The purpose of this study was to explore the contribution of psychological state to both the ventilatory response and the intensity of dyspnea experie nced after the addition of small inspiratory loads to breathing. We hypothe sized that patients with either a specific psychiatric diagnosis or a speci fic psychological trait will associate a greater degree of dyspnea with a l oaded breathing task than will control subjects. To insure the inclusion of persons with relevant psychological profiles, we recruited both subjects e nrolled in the Chronic Fatigue Center and normal control subjects. In all, 52 subjects inspired first through a small (1.34 cm H2O/L/s) and second thr ough a moderate (3.54 cm H2O/L/s) inspiratory resistive load (IRL). Ventila tion was monitored throughout the 5-min sessions. Dyspnea was quantified wi th the Borg scale at specified times during the protocol. Standard psycholo gical tests were administered. We found that subjects could be divided into two groups. One, the "responders," reported Borg scores higher than those of the second, or "nonresponder" group, at all times during the protocol. B y contrast, there was no difference between groups with respect to ventilat ion. Responders had higher scores on tests of depression (the Center for Ep idemiological Study depression scale) than did nonresponders. We conclude t hat the variability observed in subjective responses to IRL is explained, i n part, by differences in psychological state.