Hypersensitivity to carbon dioxide in panic disorder

Studies have shown that inhalation of carbon dioxide can induce panic in panic disorder patients, the point of panic coinciding with high carbon dioxide concentrations in the blood. Panic patients may be hypersensitive to carbon dioxide. Patients with a history of panic attacks and control subjects were placed under a clear plastic canopy and told that carbon dioxide would be added to the air they were breathing and that they might experience anxiety. The patients were given room air for 20 minutes; five percent carbon dioxide was added to the room air for another 20 minutes without their knowledge. Blood samples were monitored for carbon dioxide concentrations, and the patients were told to report any symptoms as soon as they occurred. The male panic patients were significantly more sensitive to carbon dioxide than the male control subjects, but anxiety levels in both groups were low and did not differ significantly. The data also suggested that there may be sex differences in panic disorder and that female panic patients may not be hypersensitive to carbon dioxide. Psychological factors known to affect carbon dioxide sensitivity were not controlled, but all subjects received the same instructions and experienced the same degree of anxiety. The physiologic differences that were recorded did not seem to be related to the levels of anxiety experienced by the subjects. (Consumer Summary produced by Reliance Medical Information, Inc.)