Spirometry in the evaluation of pulmonary function.

Spirometry should be more widely used in routine examinations. Equipment should meet the individual physician's or hospital's needs and include either a dependable water-sealed spirometer or an easily calibrated and accurate electronic spirometer. Justifiable concern over the reliability of electronic spirometers has resulted in requests to determine performance standards for these medical devices. Predicted normal standards must apply to the particular spirometer. Recommended tests are those of vital capacity (VC), forced vital capacity (FVC), one-second forced expiratory volume (FEV(1)), the ratio of one-second forced expiratory flow (FEF200-1200) and forced midexpiratory flow (FEF25-75 percent). The maximum voluntary ventilation (MVV) test may be useful for evaluation of work disability and detection of extrathoracic obstruction. Additional consideration may be given to measurements of total lung capacity (TLC) to discriminate between restrictive and obstructive impairment and the forced end-expiratory flow (FEF75-85 percent) to detect mild small airway obstruction. At this time, flow-volume curves measurement cannot be justified for routine clinical use.