van den Hout M A, Griez E, van der Molen G M, Lousberg H
J Behav Ther Exp Psychiatry. 1987 Mar;18(1):19-23. doi: 10.1016/0005-7916(87)90067-x.
Experimental research has demonstrated that CO2 inhalation provides a valid laboratory model for acute panic. Earlier studies employed CO2/O2 mixtures that were not only hypercapnic but also hyperoxic, raising the question of the relative contribution of the hyperoxidity. A comparison between a hypercapnic/hyperoxic mixture (35% CO2/65% O2) and a hypercapnic/normoxic mixture (35% CO2/20% O2/45% N2) revealed no differences on self-reported panic symptoms or end tidal pCO2. It is concluded that findings from previous CO2/O2 inhalation studies should be attributed to the hypercapnic, rather than to the hyperoxic, nature of the mixtures.
