Randomized Clinical Trial of Capnometry-Assisted Respiratory Training in Veterans With Posttraumatic Stress Disorder Hyperarousal

Objective: To investigate whether capnometry-assisted antihyperventilation respiratory training, successful in treating panic, and sleep hygiene instructions would reduce posttraumatic stress disorder (PTSD) hyperarousal symptoms in U.S. military veterans. Method: We conducted a parallel, nonblinded clinical trial and randomized 80 veterans with PTSD hyperarousal into treatment or wait list. Primary treatment outcomes from baseline to 1st follow-up were analyzed using mixed modeling. Baseline physiological measures were compared between the PTSD hyperarousal group and a no-PTSD group (n = 68). Results: Baseline respiration rate but not partial-pressure of end-tidal carbon dioxide (PCO2) was higher in the PTSD hyperarousal group than in the no-PTSD group during 3 min of quiet sitting, indicating no difference in baseline hyperventilation. There was no significant effect of the intervention on PTSD hyperarousal symptoms or hyperventilation compared to wait list, but treatment did lower respiratory rate. Conclusion: This intervention did not reduce PTSD hyperarousal symptoms, perhaps due to differences between underlying mechanisms of PTSD hyperarousal and panic disorder or to differences between veteran and civilian populations. Clinical Impact Statement This study shows that an antihyperventilation biofeedback therapy successful in treating panic in civilians failed to alleviate the posttraumatic stress disorder (PTSD) hyperarousal symptoms of military veterans, even when combined with sleep hygiene instructions. Thus, a physiological intervention targeting hyperarousal failed to relieve the hyperarousal symptoms diagnostic of PTSD. Our results, like those of many other studies attempting to treat military PSTD, highlight the need for discovering new effective interventions for this population and the importance of understanding mechanisms of action in existing treatments.