Fear talk versus voluntary hyperventilation in agoraphobics and normals: a controlled study.

Twenty-three drug-free patients with agoraphobia and panic disorder (DSM-III criteria) had, at rest, lower mean end-tidal PCO2 (32 v. 36 mmHg) and higher mean heart rate (92 v. 83 bpm) than did 18 controls. During 5 min of listening to fear talk, only eight (35%) patients and three (16%) controls panicked, but panic was associated with marked physiological changes in only two patients and one control. Patients said that breathlessness began slightly more often before than after panic. In 59% of patients the symptoms from voluntary hyperventilation (VHV) were very similar or identical to those of their usual panics. Compared with the remainder, these patients felt more unpleasant during hyperventilation (HV); in such patients HV may aggravate somatic symptoms. Agoraphobics with panic differed from controls in having higher baseline arousal, but were not more reactive than controls to HV or fear talk.