title: Elastic properties of the central airways in obstructive lung diseases measured using anatomical optical coherence tomography.
abstract: BACKGROUND
  Our understanding of how airway remodeling affects regional airway elastic properties is limited due to technical difficulties in quantitatively measuring dynamic, in vivo airway dimensions. Such knowledge could help elucidate mechanisms of excessive airway narrowing.
  
  
  OBJECTIVE
  To use anatomical optical coherence tomography (aOCT) to compare central airway elastic properties in control subjects and those with obstructive lung diseases.
  
  
  METHODS
  After bronchodilation, airway lumen area (Ai) was measured using aOCT during bronchoscopy in control subjects (n = 10) and those with asthma (n = 16), chronic obstructive pulmonary disease (COPD) (n = 9), and bronchiectasis (n = 8). Ai was measured in each of generations 0 to 5 while airway pressure was increased from -10 to 20 cm H(2)O. Airway compliance (Caw) and specific compliance (sCaw) were derived from the transpulmonary pressure (Pl) versus Ai curves.
  
  
  RESULTS
  Caw decreased progressively as airway generation increased, but sCaw did not differ appreciably across the generations. In subjects with asthma and bronchiectasis, Caw and sCaw were similar to control subjects and the Pl-Ai curves were left-shifted. No significant differences were observed between control and COPD groups.
  
  
  CONCLUSIONS
  Proximal airway elastic properties are altered in obstructive lung diseases. Although central airway compliance does not differ from control subjects in asthma, bronchiectasis, or COPD, Ai is lower in asthma and the Pl-Ai relationship is left-shifted in both asthma and bronchiectasis, suggesting that airways are maximally distended at lower inflating pressures. Such changes reflect alteration in the balance between airway wall distensibility and radial traction exerted on airways by surrounding lung parenchyma favoring airway narrowing. Clinical trial registered with Australian New Zealand Clinical Trials Registry (ACTRN12607000624482).
authors.affiliation: Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Perth, Australia. jonowilliamson@ozemail.com.au
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Williamson
authors.forename: Robert A
authors.initials: RA
authors.lastname: McLaughlin
authors.forename: William J
authors.initials: WJ
authors.lastname: Noffsinger
authors.forename: Alan L
authors.initials: AL
authors.lastname: James
authors.forename: Vanessa A
authors.initials: VA
authors.lastname: Baker
authors.forename: Andrea
authors.initials: A
authors.lastname: Curatolo
authors.forename: Julian J
authors.initials: JJ
authors.lastname: Armstrong
authors.forename: Adrian
authors.initials: A
authors.lastname: Regli
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Shepherd
authors.forename: Guy B
authors.initials: GB
authors.lastname: Marks
authors.forename: David D
authors.initials: DD
authors.lastname: Sampson
authors.forename: David R
authors.initials: DR
authors.lastname: Hillman
authors.forename: Peter R
authors.initials: PR
authors.lastname: Eastwood
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001999:Bronchoscopy; D004548:Elasticity; D005260:Female; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008170:Lung Compliance; D008173:Lung Diseases, Obstructive / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D041623:Tomography, Optical Coherence / Q000379:methods*; D055815:Young Adult