Use of noseclips in pulmonary function tests

Spirometry was performed on 136 male industrial workers experienced in undergoing pulmonary function testing for the purpose of studying the effects of the use of noseclips on forced vital capacity (FVC) maneuvers. A cross-over design was employed with each subject serving as his own reference. Forced expiratory volume in 1 second (FEV1) and FVC measurements were recorded adhering closely to the guidelines set down by the American Thoracic Society. Assuming that a 30-ml difference in FVC and FEV1 is not important, we conclude that these measurements are not significantly affected by the use of noseclips. However, trial order was found to affect the outcome. The FVC and FEV1 values on the first trial were consistently lower than those on the second regardless of noseclip use. Many subjects experienced discomfort from noseclips and their use is not recommended for routine purposes.