In an attempt to reproduce the findings of Rapee et al (1986) that ins
tructional set could alter the anxiogenic effects of carbon dioxide in
halation, 45 patients with panic disorder received two sets of instruc
tions and then underwent a series of respiratory challenges (room air
hyperventilation, 5% and 7% CO2 inhalation), The instructions failed t
o alter the anxiogenic response to any of the interventions.