Laboratory response of patients with panic and obsessive-compulsive disorders to 35% CO2 challenges.
OBJECTIVE
The DSM-III-R anxiety disorders section includes both panic disorder and obsessive-compulsive disorder. To evaluate the relationship between these two disorders, subject responses to inhalation of a 35% CO2 and 65% O2 mixture were assessed.


METHODS
Twenty-three patients with panic disorder, 23 with obsessive-compulsive disorder, 12 with both obsessive-compulsive and panic disorder, and 23 healthy comparison subjects were given a single vital capacity inhalation of 35% CO2 and 65% O2 or a placebo mixture of compressed air. A double-blind, random, crossover design was used.


RESULTS
Patients with panic disorder and patients with both panic disorder and obsessive-compulsive disorder showed similar strong anxiogenic reactions to 35% CO2; while patients with obsessive-compulsive disorder alone did not differ from comparison subjects.


CONCLUSIONS
These results confirm that obsessive-compulsive disorder and panic disorder are two distinct syndromes and that patients with these disorders have different sensitivity to CO2 inhalation.
Perna
G
G
Department of Neuropsychiatric Sciences, San Raffaele Hospital, University of Milan, Italy.
Bertani
A
A
Arancio
C
C
Ronchi
P
P
Bellodi
L
L
D000280:Administration, Inhalation; D000328:Adult; D001008:Anxiety Disorders / Q000139:chemically induced; D002245:Carbon Dioxide / Q000494:pharmacology; D015897:Comorbidity; D003937:Diagnosis, Differential; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis* / Q000453:epidemiology; D010100:Oxygen / Q000008:administration & dosage; D016584:Panic Disorder / Q000175:diagnosis* / Q000453:epidemiology; D010919:Placebos
D010919:Placebos; D002245:Carbon Dioxide; D010100:Oxygen