Physiological, subjective and behavioral responses to hyperventilation in clinical and infrequent panic.

This study investigated the physiological, subjective and behavioral responses to hyperventilation of four groups of Ss with: (1) clinical panic disorder (n = 13); (2) infrequent panic (n = 16); (3) no panic and high trait anxiety (n = 16); and (4) no panic and low trait anxiety. After completing a number of anxiety-related questionnaires, Ss participated in 2 min of hyperventilation during which heart rate and electrodermal activity were recorded continuously. Subjective sensations and cognitions during hyperventilation were assessed immediately following the task. After recovery, Ss could participate in a second, optional hyperventilation from which they could escape at any time. Analyses revealed no group differences in physiological responses to the hyperventilation, although group differences in subjective sensations and cognitions were found. Data are discussed with regards to the role of physiological processes vs subjective responses to anxiety-provoking stimuli in the psychopathology of clinical panic disorder.