title: Diffusing capacity dependent on lung volume and age in normal subjects.
abstract: In this study we determined reference values of total diffusing capacity of carbon monoxide (DLCO) and DLCO per liter alveolar volume (DLCO/VA) at total lung capacity (TLC) and at lung volumes below TLC in sitting position. In 55 healthy nonsmoking volunteers (20-85 yr old), we determined reference values at TLC level in which age was the only parameter. In a subgroup (n = 16) these references did not change by correction for normal variability in hemoglobin concentration. In all volunteers DLCO decreased and DLCO/VA increased with decreasing VA. The increase in DLCO/VA was linear and less in older subjects. We derived equations to calculate reference values of DLCO/VA for lung volumes at and below TLC with two methods: 1) "random coefficients linear" model, which calculates the reference values directly, and 2) a conversion method, which calculates DLCO/VA for lower VA levels from reference values at TLC. An advantage of the conversion method is the suitability of DLCO/VA reference values at TLC of other populations. A disadvantage is the greater standard deviation of these reference values compared with those obtained by the random coefficients linear method. DLCO can be found by multiplying DLCO/VA with VA.
authors.affiliation: Department of Pulmonary Diseases, Erasmus University, Rotterdam, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Stam
authors.forename: V
authors.initials: V
authors.lastname: Hrachovina
authors.forename: T
authors.initials: T
authors.lastname: Stijnen
authors.forename: A
authors.initials: A
authors.lastname: Versprille
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D002248:Carbon Monoxide; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000033:anatomy & histology* / Q000502:physiology*; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D011650:Pulmonary Alveoli / Q000502:physiology; D011653:Pulmonary Diffusing Capacity / Q000502:physiology*; D012016:Reference Values; D014109:Total Lung Capacity / Q000502:physiology
chemical_list: D006454:Hemoglobins; D002248:Carbon Monoxide