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

BACKGROUND

Increased anxiety and panic to inhalation of carbon dioxide (CO(2)) 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 CO(2).

METHODS

In 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% CO(2).

RESULTS

Patients with PTSD showed an increased anxiety, panic and dissociative reaction to the inhalation of 35% CO(2) 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 CO(2).

CONCLUSIONS

In our sample, PTSD was associated with an increased CO(2) reactivity, pointing to an increased susceptibility of PTSD patients to CO(2) challenge.

The effects of CO2 inhalation in patients with chronic post-traumatic stress disorder (PTSD)

Introduction

Panic disorder and post-traumatic stress disorder (PTSD), which is currently classified as an anxiety disorder in DSM-IV, share some clinical characteristics. Emerging evidence suggests that CO2-induced fear reactivity is associated with anxiety disorders, especially panic disorder. However, there are only very few data available about the sensitivity of patients with PTSD to carbon dioxide.

Aim

To examine the psychometric effects of CO2 on panic anxiety and PTSD symptoms in subjects with PTSD.

Methods

In 10 patients with PTSD, 10 sex- and age-matched healthy subjects and additional 8 patients with panic disorder we assessed anxiety, panic, dissociative and PTSD symptoms before and after a single vital capacity inhalation of 35% CO2.

Results

Inhalation of a single deep breath of 35% of carbon dioxide resulted in significant panicogenic and anxiogenic effects in PTSD patients versus healthy controls, which were similar to the well known responses of patients with panic disorder. Furthermore, significant pro-dissociative effects and significant provocation of post-traumatic flashbacks and PTSD symptoms were observed in PTSD patients.

Conclusions

These data provide novel evidence that panic disorder and PTSD share a common hypersensitivity to CO2 and thus might belong to the same spectrum of vulnerability.