Acute panicogenic, anxiogenic and dissociative effects of carbon dioxide inhalation in patients with post-traumatic stress disorder (PTSD)

BackgroundIncreased anxiety and panic to inhalation of carbon dioxide (CO2) has been described in patients with anxiety disorders, especially panic disorder, compared to healthy subjects. Post-traumatic stress disorder (PTSD) has been hypothesised to resemble panic disorder and is currently classified as an anxiety disorder in DSM-IV. However, there are only very few data available about the sensitivity of patients with PTSD to CO2.MethodsIn 10 patients with PTSD, 10 sex- and age-matched healthy subjects and 8 patients with panic disorder we assessed anxiety, panic, dissociative and PTSD symptoms before and after a single vital capacity inhalation of 35% CO2.ResultsPatients with PTSD showed an increased anxiety, panic and dissociative reaction to the inhalation of 35% CO2 compared to healthy participants. PTSD subjects’ responses were indistinguishable from those of panic patients. Additionally, PTSD-typical symptoms like post-traumatic flashbacks were provoked in patients with PTSD after the inhalation of CO2.ConclusionsIn our sample, PTSD was associated with an increased CO2 reactivity, pointing to an increased susceptibility of PTSD patients to CO2 challenge.