Abstract

The characteristics and performance of the Vitalograph dry spirometer were studied using the criteria suggested by the International Labour Organisation (I.L.O.) Report on the standardization of respiratory function tests in pneumoconiosis. Comparison was also made with the Bernstein spirometer. The recorder speed, activation volume, and accuracy of volume calibration and linearity comply with most of the suggestions in the I.L.O. Report. The combined resistance and inertia of the Vitalograph exceed the limits cited in the report, however, and are also greater than those reported for the Bernstein and other spirometers. Nevertheless, the Vitalograph calibrates well against the Bernstein for vital capacity and FEV₁ measurements made in normal subjects and in patients with obstructive airways disease. It is therefore suggested that it may be suitable for the assessment of forced expiratory volume and vital capacity in patients and normal subjects, or in population survey work. The fact that it is lightweight, portable, and robust is also an advantage.