Rationale: In elderly subjects, static lung volumes are interpreted using prediction equations derived from primarily younger adult populations.
Objectives: To provide reference equations for static lung volumes for European adults 65 to 85 years of age and to compare the predicted values of this sample with those from other studies including middle-aged adults. We compare the lung volumes by plethysmography and helium dilution in elderly subjects.
Methods: Reference equations were derived from a randomly selected sample from the general population of 321 healthy never-smoker subjects 65 to 85 years of age. Spirometry and lung volume determinations by plethysmography and multibreath helium equilibration method were performed following the American Thoracic Society/European Respiratory Society recommendations. Reference values and lower and upper limits of normal were derived using a piecewise polynomial model.
Measurements and main results: Plethysmography provided higher values than the dilutional method for all lung volumes, with wide limits of agreement. In addition to height, our reference equations confirm the age- and body size dependence of lung volumes in older subjects. Practically all the estimations performed by extrapolating reference equations of middle-aged adults overpredicted the true lung volumes of our healthy elderly volunteers. Middle-aged reference equations classify subjects as being below the total lung capacity lower limit of normal between 17.9 and 62.5% of the women and between 12.5 and 42.2% of the men of the current study.
Conclusions: These results underscore the importance of using prediction equations appropriate to the origin, age, and height characteristics of the subjects being studied.