RESPIRATORY PSYCHOPHYSIOLOGY AND ANXIETY - COGNITIVE INTERVENTION IN THE DOXAPRAM MODEL OF PANIC

The goals of this study were to: a) confirm prior evidence that the re spiratory stimulant doxapram induces panic attacks and produces excess ive hyperventilation in patients with panic disorder and b) explore th e impact of cognitive mediators on symptom and respiratory responses, Method: Thirty-two subjects (16 patients and 16 controls) received dox apram (0.5 mg/kg) and placebo infusions while symptom, respiratory, an d heart rate responses were monitored. Subjects were randomly assigned to receive either a standard introduction or a cognitive intervention designed to reduce the panic responses of panic patients to laborator y challenges. Results: Doxapram was a potent and specific panicogenic agent, inducing panic in 75% of patients and 12.5% of controls. Compar ed with controls, patients also showed a greater decrease in end tidal carbon dioxide (CO2) and greater increases in minute ventilation, res piratory frequency, and heart rate. The cognitive intervention substan tially attenuated the excessive hyperventilatory response of patients but did not fully normalize their breathing patterns. Tidal volume was the only respiratory measure not significantly altered by the cogniti ve intervention. Conclusions: In patients with panic disorder, doxapra m (0.5 mg/kg) triggers panic attacks about as potently as 7% CO2 and m ore potently than 5% CO2 of lactate, Psychological factors can modulat e the appearance of ventilatory abnormalities in panic patients, but p ersistent respiratory disturbances were still seen. Psychological fact ors and respiratory physiology both appear to be important phenomena i n laboratory panic.