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Behavioral and cardiovascular effects of 7.5% CO 2 in human volunteers
Author(s) -
Bailey Jayne E.,
Argyropoulos Spilios V.,
Kendrick Adrian H.,
Nutt David J.
Publication year - 2005
Publication title -
depression and anxiety
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.634
H-Index - 129
eISSN - 1520-6394
pISSN - 1091-4269
DOI - 10.1002/da.20048
Subject(s) - anxiety , panic , inhalation , heart rate , panic disorder , arousal , anxiolytic , blood pressure , provocation test , placebo , anesthesia , psychology , medicine , psychiatry , neuroscience , alternative medicine , pathology
Abstract The study of carbon dioxide (CO 2 ) inhalation in psychiatry has a long and varied history, with recent interest in using inhaled CO 2 as an experimental tool to explore the neurobiology and treatment of panic disorder. As a consequence, many studies have examined the panic‐like response to the gas either using the single or double breath 35% CO 2 inhalation or 5–7% CO 2 inhaled for 15–20 min, or rebreathing 5% CO 2 for a shorter time. However, this lower dose regime produces little physiological or psychological effects in normal volunteers. For this reason we have studied the effects of a higher concentration of CO 2 , 7.5%, given over 20 min. Twenty healthy volunteers were recruited to a double blind, placebo‐controlled study where air and 7.5% CO 2 were inhaled for 20 min. Cardiovascular measures and subjective ratings were obtained. When compared to air, inhaling 7.5% CO 2 for 20 min increases systolic blood pressure and heart rate, indicating increased autonomic arousal. It also increases ratings of anxiety and fear and other subjective symptoms associated with an anxiety state. The inhalation of 7.5% CO 2 for 20 min is safe for use in healthy volunteers and produces robust subjective and objective effects. It seems promising as an anxiety provocation test that could be beneficial in the study of the effects of anxiety on sustained performance, the discovery of novel anxiolytic agents, and the study of brain circuits and mechanisms of anxiety. Depression and Anxiety 00:000–000, 2005. © 2005 Wiley‐Liss, Inc.