title: Effect of antipanic treatment on response to carbon dioxide.
abstract: BACKGROUND
  Disordered breathing among patients with panic disorder, including hyperventilation during attacks and increased anxiogenic response to carbon dioxide (CO2) inhalation, is well established. We wished to assess whether there is a change in the physiological response to CO2 after patients have undergone antipanic therapy with either tricyclic antidepressants or cognitive behavioral therapy (CBT).
  
  
  METHODS
  Twenty-nine patients with panic disorder underwent baseline CO2 sensitivity testing using the traditional Read rebreathing method and then received either antidepressant treatment (n = 21) or CBT (n = 8). After completing treatment, CO2 testing was repeated. A comparison sample of 14 normal volunteers also had two CO2 sensitivity tests, separated by an average of 21.6 (SD = 8.8) weeks.
  
  
  RESULTS
  Using a liberal standard, in which all CO2 sensitivity tests whose correlations between minute ventilation and end-tidal CO2 were at least .75 were used, patients, but not controls, demonstrated a significant reduction in CO2 sensitivity between the first and second test. Using a more conservative .90 correlation standard reduced the sample size available and resulted in trend reduction in patients but no significant change in controls. There was a suggestion that the change was most pronounced in treatment responders, although the number of patient nonresponders is extremely small in this sample.
  
  
  CONCLUSIONS
  These data indicate that treatment reduces CO2 sensitivity in patients with panic disorder. We speculate that manipulation of the serotonergic and noradrenergic neurotransmission systems, both known to play a role in the control of respiration, may have a specific effect in reducing respiratory hyperactivity in panic disorder.
authors.affiliation: Biological Studies Unit, New York State Psychiatric Institute, New York, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Gorman
authors.forename: S T
authors.initials: ST
authors.lastname: Browne
authors.forename: L A
authors.initials: LA
authors.lastname: Papp
authors.forename: J
authors.initials: J
authors.lastname: Martinez
authors.forename: L
authors.initials: L
authors.lastname: Welkowitz
authors.forename: J D
authors.initials: JD
authors.lastname: Coplan
authors.forename: R R
authors.initials: RR
authors.lastname: Goetz
authors.forename: J
authors.initials: J
authors.lastname: Kent
authors.forename: D F
authors.initials: DF
authors.lastname: Klein
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000929:Antidepressive Agents, Tricyclic / Q000627:therapeutic use; D001521:Behavior Therapy; D002245:Carbon Dioxide / Q000008:administration & dosage / Q000494:pharmacology*; D015928:Cognitive Behavioral Therapy; D005260:Female; D006801:Humans; D007099:Imipramine / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D016584:Panic Disorder / Q000188:drug therapy / Q000503:physiopathology* / Q000628:therapy*; D011569:Psychiatric Status Rating Scales
chemical_list: D000929:Antidepressive Agents, Tricyclic; D002245:Carbon Dioxide; D007099:Imipramine