Diagnostic and substance specificity of carbon-dioxide-induced panic.
OBJECTIVE
The authors assessed the substance and diagnostic specificity of carbon-dioxide-induced panic since, in addition to the specific biochemical effects of inhaled carbon dioxide (CO2), simple physiologic distress is also frequently implicated as a panicogenic factor during respiratory challenge studies with CO2 in patients with anxiety disorders.


METHODS
Eighteen patients with panic disorder, 20 with social phobia, and 23 psychiatrically normal subjects inhaled a mixture of 35% CO2 and 65% O2 for 30 seconds through a face mask. They also breathed for 30 seconds through a valve reducing the diameter of the airway. A double-blind, counterbalanced, randomized design was used.


RESULTS
In spite of important similarities between the two interventions, including the induction of equal amounts of subjective respiratory distress, carbon dioxide inhalation was significantly more potent than increased airway resistance in provoking panic in the anxiety disorder patients. The patients with panic disorder were significantly more sensitive to CO2 than were the patients with social phobia or the normal subjects.


CONCLUSIONS
Carbon dioxide inhalation appears to have a specific panicogenic effect in panic patients that goes beyond simple breathlessness.
Papp
L A
LA
Biological Studies Unit, New York State Psychiatric Institute, NY 10032.
Klein
D F
DF
Martinez
J
J
Schneier
F
F
Cole
R
R
Liebowitz
M R
MR
Hollander
E
E
Fyer
A J
AJ
Jordan
F
F
Gorman
J M
JM
D000280:Administration, Inhalation; D000328:Adult; D002245:Carbon Dioxide / Q000008:administration & dosage / Q000494:pharmacology; D003937:Diagnosis, Differential; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D016584:Panic Disorder / Q000139:chemically induced / Q000175:diagnosis* / Q000523:psychology; D010698:Phobic Disorders / Q000175:diagnosis / Q000523:psychology; D012119:Respiration / Q000187:drug effects
D002245:Carbon Dioxide