title: Exaggerated anxiety is not unique to CO2 in panic disorder: a comparison of hypercapnic and hypoxic challenges.
abstract: Current biological models of panic disorder (PD) assert that this disorder is maintained by hypersensitivity to carbon dioxide (CO2) and related asphyxia cues, which is manifested as an exaggerated suffocation alarm (D. Klein, 1993). Because suffocation can result from both increased CO2 (hypercapnia) and decreased oxygen (O2; hypoxia), this study examined respiratory responding and anxiety during 5% CO2 (a hypercapnic challenge) and 12% O2 (a hypoxic challenge) in 14 PD patients and 14 matched controls (MC). Results demonstrate that irrespective of the source of suffocation, PD patients respond with increased anxiety relative to MC participants. Significant group differences were observed in respiratory functioning, with the PD patients showing higher respiratory rates in response to both challenges. The MC sample demonstrated the expected respiratory responses to both hypercapnia and hypoxia. The findings indicate that PD patients are hypersensitive to alterations in breathing and that this reactivity is not specific to CO2.
authors.affiliation: Department of Psychology, State University of New York at Buffalo 14260, USA. jgbeck@acsu.buffalo.edu
authors.forename: J G
authors.initials: JG
authors.lastname: Beck
authors.forename: P J
authors.initials: PJ
authors.lastname: Ohtake
authors.forename: J C
authors.initials: JC
authors.lastname: Shipherd
mesh_terms: D000328:Adult; D001007:Anxiety / Q000139:chemically induced*; D002245:Carbon Dioxide / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000139:chemically induced* / Q000175:diagnosis; D000860:Hypoxia / Q000139:chemically induced* / Q000175:diagnosis; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D016584:Panic Disorder / Q000139:chemically induced* / Q000175:diagnosis; D012720:Severity of Illness Index
chemical_list: D002245:Carbon Dioxide