410.430—Ventilatory studies.
Spirometric tests to measure ventilatory function must be expressed in liters or liters per minute. The reported maximum voluntary ventilation (MVV) or maximum breathing capacity (MBC) and 1-second forced expiratory volume (FEV1) should represent the largest of at least three attempts. The MVV or the MBC reported should represent the observed value and should not be calculated from FEV1. The three appropriately labeled spirometric tracings, showing distance per second on the abscissa and the distance per liter on the ordinate, must be incorporated in the file. The paper speed to record the FEV1 should be at least 20 millimeters (mm.) per second. The height of the individual must be recorded. Studies should not be performed during or soon after an acute respiratory illness. If wheezing is present on auscultation of the chest, studies must be performed following administration of nebulized broncho-dilator unless use of the later is contraindicated. A statement shall be made as to the individual's ability to understand the directions, and cooperate in performing the tests. If the tests cannot be completed the reason for such failure should be explained.