title: Effect of volume history on changes in DLcoSB-3EQ with lung volume in normal subjects.
abstract: The purpose of this study was to determine the relationship between the three-equation diffusing capacity for carbon monoxide (DLcoSB-3EQ) and lung volume and to determine how this relationship was altered when maneuvers were immediately preceded by a deep breath. DLcoSB-3EQ maneuvers were performed in nine healthy subjects either immediately after a deep breath or after tidal breathing for 10 min. The maneuvers consisted of slow inhalation of test gas from functional residual capacity to 25, 50, 75, or 100% of the inspiratory capacity and, without breath holding, slow exhalation to residual volume. After either a deep breath or tidal breathing, we found that DLcoSB-3EQ decreased nonlinearly with decreasing lung volume. At all lung volumes, DLcoSB-3EQ was significantly greater when measured after a deep breath than after tidal breathing. This effect increased as lung volume decreased, so that the greatest difference between DLcoSB-3EQ after a deep breath and that after tidal breathing occurred at the lowest lung volume. We conclude that a deep breath or spontaneous sigh has a role in reestablishing the pathway for gas exchange during tidal breathing.
authors.affiliation: Department of Medicine, University of Saskatchewan, Saskatoon, Canada.
authors.forename: D J
authors.initials: DJ
authors.lastname: Cotton
authors.forename: F
authors.initials: F
authors.lastname: Taher
authors.forename: J T
authors.initials: JT
authors.lastname: Mink
authors.forename: B L
authors.initials: BL
authors.lastname: Graham
mesh_terms: D000328:Adult; D002248:Carbon Monoxide / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000033:anatomy & histology / Q000502:physiology*; D008176:Lung Volume Measurements; D011650:Pulmonary Alveoli / Q000502:physiology; D014109:Total Lung Capacity
chemical_list: D002248:Carbon Monoxide