Michael Kellner1, Christoph Muhtz2, Sven Nowack3, Irina Leichsenring3, Klaus Wiedemann3, Alexander Yassouridis4. 1. University Hospital Hamburg-Eppendorf, Dept. of Psychiatry and Psychotherapy, Martinistrasse 52, 20246 Hamburg, Germany; Hospital Herford, Dept. of Psychiatry, Psychotherapy and Psychosomatics, Schwarzenmoorstraße 70, 32049 Herford, Germany. Electronic address: michael.kellner@klinikum-herford.de. 2. University Hospital Hamburg-Eppendorf, Dept. of Psychiatry and Psychotherapy, Martinistrasse 52, 20246 Hamburg, Germany; Schön Hospital Hamburg Eilbek, Department of Psychosomatics, Dehnhaide 120, 22081 Hamburg, Germany. 3. University Hospital Hamburg-Eppendorf, Dept. of Psychiatry and Psychotherapy, Martinistrasse 52, 20246 Hamburg, Germany. 4. Max Planck Institute of Psychiatry, Kraepelinstrasse 2-10, 80804 Munich, Germany.
Abstract
BACKGROUND: In patients with post-traumatic stress disorder (PTSD) two open pilot studies about the effects of 35% carbon dioxide (CO2) exist. One shows an augmented panicogenic and anxiogenic response (Muhtz et al., 2011), the other does not (Talesnik et al. 2007). We further characterized the CO2 reactivity in PTSD using for the first time placebo-controlled and double-blind conditions. METHODS: In 20 patients with PTSD we assessed panic, anxiety, dissociative and PTSD symptoms after a single vital capacity inhalation of 35% CO2 compared to a placebo gas condition in a within-participant cross-over, placebo-controlled, double-blind and randomized design. RESULTS: Inhalation of 35% CO2 versus placebo provoked significantly increased panic, anxiety, dissociative and PTSD symptoms. The reaction to placebo gas was minimal. Order of inhalation, patients' sex or age did not influence the results. The panic and anxiety response under CO2 was considerably higher in the PTSD patients than in healthy controls from our previous open study. CONCLUSIONS: The results corroborate that our preceding findings of an increased CO2 reactivity in patients with PTSD are not false positive due to the open design or the lack of placebo control. Replication in a larger number of PTSD patients and matched control subjects is needed. The potential role of childhood traumatisation, psychiatric comorbidity, psychotropic medication and trait dissociation in prior contradictory reports should be clarified.
RCT Entities:
BACKGROUND: In patients with post-traumatic stress disorder (PTSD) two open pilot studies about the effects of 35% carbon dioxide (CO2) exist. One shows an augmented panicogenic and anxiogenic response (Muhtz et al., 2011), the other does not (Talesnik et al. 2007). We further characterized the CO2 reactivity in PTSD using for the first time placebo-controlled and double-blind conditions. METHODS: In 20 patients with PTSD we assessed panic, anxiety, dissociative and PTSD symptoms after a single vital capacity inhalation of 35% CO2 compared to a placebo gas condition in a within-participant cross-over, placebo-controlled, double-blind and randomized design. RESULTS: Inhalation of 35% CO2 versus placebo provoked significantly increased panic, anxiety, dissociative and PTSD symptoms. The reaction to placebo gas was minimal. Order of inhalation, patients' sex or age did not influence the results. The panic and anxiety response under CO2 was considerably higher in the PTSDpatients than in healthy controls from our previous open study. CONCLUSIONS: The results corroborate that our preceding findings of an increased CO2 reactivity in patients with PTSD are not false positive due to the open design or the lack of placebo control. Replication in a larger number of PTSDpatients and matched control subjects is needed. The potential role of childhood traumatisation, psychiatric comorbidity, psychotropic medication and trait dissociation in prior contradictory reports should be clarified.