Differential Response to Hyperventilation in Panic Disorder and Generalized Anxiety Disorder

Twenty subjects with panic disorder and 13 subjects with generalized anxiety disorder were compared on their subjective responses to 90 s of voluntary hyperventilation and on three physiological measures. Subjects with panic disorder reported a markedly greater distress and a greater number of symptoms in response to the voluntary hyperventilation and, in addition, showed a lower resting partial pressure of carbon dioxide (pCO ₂) and higher resting heart rate than subjects with generalized anxiety disorder. No differences were found on minute respiratory volume. The implications of these findings for a potential role of hyperventilation in panic attacks are discussed.