title: Lumen areas and homothety factor influence airway resistance in COPD.
abstract: The remodelling process of COPD may affect both airway calibre and the homothety factor, which is a constant parameter describing the reduction of airway lumen (h(d): diameter of child/parent bronchus) that might be critical because its reduction would induce a frank increase in airway resistance. Airway dimensions were obtained from CT scan images of smokers with (n=22) and without COPD (n=9), and airway resistance from plethysmography. Inspiratory airway resistance correlated to lumen area of the sixth bronchial generation of right lung, while peak expiratory flow correlated to the area of the third right generation (p=0.0009, R=0.57). A significant relationship was observed between h(d) and resistance (p=0.036; R(2)=0.14). A modelling approach of central airways (5 generations) further described the latter relationship. In conclusion, a constant homothety factor can be described by CT scan analysis, which partially explains inspiratory resistance, as predicted by theoretical arguments. Airway resistance is related to lumen areas of less proximal airways than commonly admitted.
authors.affiliation: Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie - Clinique de la Dyspnée, France.
authors.forename: Plamen
authors.initials: P
authors.lastname: Bokov
authors.forename: Benjamin
authors.initials: B
authors.lastname: Mauroy
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Revel
authors.forename: Pierre-Amaury
authors.initials: PA
authors.lastname: Brun
authors.forename: Claudine
authors.initials: C
authors.lastname: Peiffer
authors.forename: Christel
authors.initials: C
authors.lastname: Daniel
authors.forename: Maria-Magdalena
authors.initials: MM
authors.lastname: Nay
authors.forename: Bruno
authors.initials: B
authors.lastname: Mahut
authors.forename: Christophe
authors.initials: C
authors.lastname: Delclaux
mesh_terms: D000368:Aged; D000403:Airway Resistance / Q000502:physiology*; D001980:Bronchi / Q000473:pathology / Q000503:physiopathology*; D001995:Bronchography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000473:pathology* / Q000503:physiopathology; D012129:Respiratory Function Tests / Q000379:methods; D012907:Smoking / Q000009:adverse effects / Q000473:pathology / Q000503:physiopathology; D014057:Tomography, X-Ray Computed / Q000379:methods; D014132:Trachea / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*