title: Hypersensitivity to hypercapnia: definition/(s).
abstract: Empirical evidence indicates that panic disorder (PD) patients experience hypersensitivity to hypercapnia, a condition in which the blood level of carbon dioxide exceeds the normal value. The importance of this research line is substantial and indeed, hypercapnic hypersensitivity has been advanced as a possible endophenotype of panic. Definitions of "hypersensitivity," however, have varied. The purpose of this brief review is to delineate and critique different definitions of hypercapnic hypersensitivity. Several definitions - panic attack rate, panic symptoms including dyspnea, subjective anxiety, and respiratory disturbance - are explored. The review concludes that although no ideal definition has emerged, marked anxiety post-hypercapnia has substantial support as a putative trait marker of PD. The term "subjective hypersensitivity" (Coryell et al., 2001) is re-introduced to denote pronounced anxiety post-hypercapnia and recommended for use along with its previous definition: increased self-reported anxiety measured on a continuous visual analog scale, already widely in use. Due to the well-established link between panic and respiration, definitional candidates focusing on aberrant respiratory response - less investigated as trait markers of PD in high risk studies - warrant scrutiny as well. Several reasons why definitional clarity might be beneficial are presented, along with ideas for future research.
authors.affiliation: Department of Psychology, Ryerson University, Toronto, ON, Canada. kvickers@ryerson.ca
authors.forename: Kristin
authors.initials: K
authors.lastname: Vickers
mesh_terms: D001007:Anxiety / Q000209:etiology; D006801:Humans; D006935:Hypercapnia / Q000175:diagnosis* / Q000503:physiopathology*; D006967:Hypersensitivity / Q000175:diagnosis* / Q000503:physiopathology*; D012120:Respiration Disorders / Q000209:etiology; D057566:Self Report