Diffusing capacity dependent on lung volume and age in normal subjects

• Published in: Journal of applied physiology (1985) Vol. 76; no. 6; p. 2356
• Main Authors: Stam, H, Hrachovina, V, Stijnen, T, Versprille, A
• Format: Journal Article
• Language: English
• Published: United States 01.06.1994
• Subjects: Adult; Aged; Aged, 80 and over; Aging - physiology; Carbon Monoxide; Female; Hemoglobins - metabolism; Humans; Lung - anatomy & histology; Lung - physiology; Lung Volume Measurements; Male; Middle Aged; Pulmonary Alveoli - physiology; Pulmonary Diffusing Capacity - physiology; Reference Values; Total Lung Capacity - physiology
• ISSN: 8750-7587
• DOI: 10.1152/jappl.1994.76.6.2356

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.