title: Respiratory pathophysiology of panic disorder: an ambulatory monitoring study.
abstract: OBJECTIVE
  To assess the external validity of laboratory baselines in panic disorder (PD), frequently associated with respiratory pattern abnormalities like increased respiratory variability and sighing, implying a stable pathophysiologic trait characteristic.
  
  
  METHODS
  Physical activity and a variety of breath-by-breath volumetric, timing, and variability measures of respiration were recorded in the daily life of 26 patients with PD and 26 healthy controls (HC), using a novel ambulatory monitoring system optimized for reliable assessment of respiratory pattern. Data were stratified for physical activity to eliminate its confounding effects.
  
  
  RESULTS
  Groups showed strong and consistent diurnal patterns in almost all respiratory variables. However, patients with PD did not differ from HC regarding any of the respiratory timing, volumetric and variability measures, with negligible group effect sizes for all measures. Patients with fewer self-reported respiratory symptoms of anxiety exhibited more pronounced rapid shallow breathing as well as diminished total breath time and its variability.
  
  
  CONCLUSIONS
  Despite state-of-the-art ambulatory assessment and sufficient statistical power to detect respiratory alterations previously observed in the laboratory, we found no evidence for such alterations in PD patients' daily life. Neither the total PD group nor patients with particularly pronounced respiratory symptomatology displayed increased respiratory variability. These results caution against interpreting results from laboratory baselines in PD as reflecting a stable trait characteristic. Rather, they likely represent a state-trait interaction due to enhanced reactivity of PD patients to novel environments. These results challenge aspects of respiratory theories of PD that were based on laboratory findings.
authors.affiliation: Faculty of Psychology, Department of Clinical Psychology and Psychotherapy, University of Basel, CH-4055 Basel, Switzerland.
authors.forename: Monique C
authors.initials: MC
authors.lastname: Pfaltz
authors.forename: Tanja
authors.initials: T
authors.lastname: Michael
authors.forename: Paul
authors.initials: P
authors.lastname: Grossman
authors.forename: Jens
authors.initials: J
authors.lastname: Blechert
authors.forename: Frank H
authors.initials: FH
authors.lastname: Wilhelm
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D001008:Anxiety Disorders / Q000175:diagnosis / Q000503:physiopathology; D015415:Biomarkers; D002940:Circadian Rhythm / Q000502:physiology; D003130:Combat Disorders / Q000503:physiopathology; D003625:Data Collection / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory / Q000379:methods / Q000706:statistics & numerical data*; D009043:Motor Activity / Q000502:physiology; D016584:Panic Disorder / Q000175:diagnosis / Q000503:physiopathology*; D010555:Personality Inventory; D015203:Reproducibility of Results; D012119:Respiration; D012120:Respiration Disorders / Q000175:diagnosis / Q000503:physiopathology; D012129:Respiratory Function Tests / Q000379:methods / Q000706:statistics & numerical data*; D012137:Respiratory System / Q000503:physiopathology*; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers