Macdonald J B, Cole T J, Seaton A
Thorax. 1975 Oct;30(5):554-9. doi: 10.1136/thx.30.5.554.
Three studies of factors affecting variability of forced expiratory time (FET) have been carried out. In the first, different observers or repeated measurements over a few minutes were shown to make no significant contribution to FET variability. Time of day was also relatively unimportant. In the second study, FET was shown to vary considerably more than peak flow rate, forced expiratory volumes, and mid expiratory flow rates over the course of five days. In the third study, FET was shown to correlate with other measurements of airways obstruction though the correlation coefficients were relatively low. The measurement of FET is thought to be too variable to be of practical use as a screening test for small airways disease, though its clinical value is not questioned.
已经开展了三项关于影响用力呼气时间（FET）变异性因素的研究。在第一项研究中，不同观察者或几分钟内的重复测量对FET变异性没有显著影响。一天中的时间相对来说也不太重要。在第二项研究中，在五天的过程中，FET的变化比峰值流速、用力呼气量和呼气中期流速的变化要大得多。在第三项研究中，尽管相关系数相对较低，但FET与气道阻塞的其他测量指标相关。FET的测量被认为变异性太大，无法作为小气道疾病的筛查试验实际应用，不过其临床价值并无争议。
