Lung function testing: methods and reference values for forced expiratory volume (FEV1) and transfer factor (TL).

Accepted 20 November 1996 Background WHICH TESTS? Almost 50 years ago Gilson et al embarked on the first large scale investigation into impaired lung function and breathlessness on exertion resulting from an occupational exposure.1 The study described the lungs in terms of their size, ventilatory power, effectiveness in distributing gas, and ability to transfer gas into the blood. The tests were chosen on account of being simple and acceptable for the subjects, requir ing only a few minutes to perform, having adequate accuracy and reproducibility, and yielding relevant information which could not be obtained more conveniently in other ways. These concepts were widely accepted.2 They pointed to a core of three general tests which should be available to occupational physicians and epidemiologists confronted by a possible respiratory hazard. In order of usefulness, the tests are ventilatory capacity (forced expiratory volume in one second and peak expiratory flow (FEVj and PEF)), transfer factor (Tl), and the physiological responses to submaximal exer cise. The tests will indicate the extent of any respiratory impairment associated with a previ ous or chronic chest illness or with cough, wheeze, or breathlessness on exertion, such as might be a consequence of breathing polluted air. In the presence of variable airflow obstruc tion, additional tests may be required.3 {Occup Environ Med 1997;54:457-465)