Do panic symptom profiles influence response to a hypoxic challenge in patients with panic disorder? A preliminary report

Objective: This study examined how panic symptom profiles affect response to a hypoxic laboratory challenge in patients with panic disorder. Methods: Seven patients whose naturally occurring panic attacks were characterized by prominent respiratory symptoms (Resp subgroup) were compared and contrasted with seven patients who did not report respiratory symptoms during panic attacks (NonResp subgroup). All were administered a novel 12% O-2 challenge and assessed with measures of tidal volume, respiratory rate, end-tidal CO2, anxiety, and panic symptoms. Results: Although the Resp and NonResp subgroups showed equivalent increases in anxiety and panic symptoms, the Resp subgroup showed greater fluctuation in tidal volume during and after the challenge as well as overall lower levels of end-tidal CO2. Conclusions: Our results suggest the importance of panic symptom profiles in determining respiratory responses to a hypoxic challenge in patients with panic disorder. These findings are discussed in light of current theories of panic disorder, with particular attention to respiratory disturbances in this disorder.