title: Respiratory patterns in panic disorder reviewed: a focus on biological challenge tests.
abstract: OBJECTIVE
  To provide a systematic review of studies investigating respiration in PD and comments on relative inconsistencies.
  
  
  METHODS
  A Medline search of controlled studies focusing on pCO(2), respiratory rate, tidal volume, and minute volume in PD patients was conducted for baseline/resting condition, challenge, and recovery phase. Respiratory variability and comparisons between panickers and non-panickers were also examined.
  
  
  RESULTS
  Lower pCO(2) levels in PD subjects are a consistent finding during the baseline/resting condition, the challenge, and recovery phases. Tidal volume and minute volume are increased in PD subjects relative to controls during the baseline/resting condition. However, the most robust finding is a higher than normal respiratory variability, which appears to be a promising factor for the identification of respiratory etiopathological pathways in PD.
  
  
  CONCLUSIONS
  Respiratory variability might be a candidate for a biological marker of PD: an abnormal breathing pattern as found in panic disorder (PD) patients compared with controls might indicate instability of the respiratory homeostasis.
authors: School of Mental Health and Neurosciences, Maastricht University, 6200 AB, Maastricht, the Netherlands.
authors: V
authors: V
authors: Niccolai
authors: M A
authors: MA
authors: van Duinen
authors: E J
authors: EJ
authors: Griez
mesh_terms: D015415:Biomarkers; D004417:Dyspnea / Q000175:diagnosis* / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D016584:Panic Disorder / Q000453:epidemiology*; D020127:Recovery of Function; D056152:Respiratory Rate; D013990:Tidal Volume
chemical_list: D015415:Biomarkers