Temporal stability of multiple response systems to 7.5% carbon dioxide challenge

Abstract

Self-reported anxiety, and potentially physiological response, to maintained inhalation of carbon dioxide (CO₂) enriched air shows promise as a putative marker of panic reactivity and vulnerability. Temporal stability of response systems during low-dose, steady-state CO₂ breathing challenge is lacking. Outcomes on multiple levels were measured two times, one week apart, in 93 individuals. Stability was highest during the CO₂ breathing phase compared to pre-CO₂ and recovery phases, with anxiety ratings, respiratory rate, skin conductance level, and heart rate demonstrating good to excellent temporal stability (ICCs≥0.71). Cognitive symptoms tied to panic were somewhat less stable (ICC=0.58) than physical symptoms (ICC=0.74) during CO₂ breathing. Escape/avoidance behaviors and DSM-5 panic attacks were not stable. Large effect sizes between task phases also were observed. Overall, results suggest good-excellent levels of temporal stability for multiple outcomes during respiratory stimulation via 7.5% CO₂.

Keywords: Carbon dioxide hypersensitivity; Heart rate; Panic attack; Panic risk; Panic symptoms; Reliability; Respiratory rate; Skin conductance; Subjective anxiety; Temporal stability.

Figure 1

Scatterplots Depicting Associations between Session 1 and Session 2 Physiological Measures and Session 1 and Session 2 Anxiety Ratings Assessed during the 7.5% CO₂ Breathing Phase of the CO₂ challenge. Rf=Respiratory Frequnecy; HR=Heart Rate; SCL=Skin Conductance Level.