title: In vivo characterization of the transitional bronchioles by aerosol-derived airway morphometry.
abstract: Effective airway dimensions (EADs) were determined in vivo by aerosol-derived airway morphometry as a function of volumetric lung depth (VLD) to identify and characterize, noninvasively, the caliber of the transitional bronchiole region of the human lung and to compare the EADs by age, gender, and disease. By logarithmically plotting EAD vs. VLD, two distinct regions of the lung emerged that were identified by characteristic line slopes. The intersection of proximal and distal segments was defined as VLD(trans) and associated EAD(trans). In our normal subjects (n = 20), VLD(trans) [345 +/- 83 (SD) ml] correlated significantly with anatomic dead space (224 +/- 34 ml) and end of phase II of single-breath nitrogen washout (360 +/- 53 ml). The corresponding EAD(trans) was 0.42 +/- 0. 07 mm, in agreement with other ex vivo measurements of the transitional bronchioles. VLD(trans) was smaller (216 +/- 64 ml) and EAD(trans) was larger (0.83 +/- 0.04 mm) in our patients with chronic obstructive pulmonary disease (n = 13). VLD(trans) increased with age for children (age 8-18 yr; P = 0.006, n = 26) and with total lung capacity for age 8-81 yr (P < 0.001, n = 61). This study extends the usefulness of aerosol-derived airway morphometry to in vivo measurements of the transitional bronchioles.
authors.affiliation: Center for Environmental Medicine and Lung Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Zeman
authors.forename: G
authors.initials: G
authors.lastname: Scheuch
authors.forename: K
authors.initials: K
authors.lastname: Sommerer
authors.forename: J S
authors.initials: JS
authors.lastname: Brown
authors.forename: W D
authors.initials: WD
authors.lastname: Bennett
mesh_terms: D000293:Adolescent; D000328:Adult; D000336:Aerosols; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001980:Bronchi / Q000033:anatomy & histology* / Q000254:growth & development / Q000502:physiology*; D002648:Child; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008168:Lung / Q000033:anatomy & histology / Q000254:growth & development; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D014109:Total Lung Capacity / Q000502:physiology
chemical_list: D000336:Aerosols