Tweeddale P M, Merchant S, Leslie M, Alexander F, McHardy G J
Thorax. 1984 Dec;39(12):928-32. doi: 10.1136/thx.39.12.928.
The natural variability in forced expiratory volume in one second (FEV1) over 20 minutes was determined in 54 fit hospital employees and 13 patients with restrictive lung disorders. Initial FEV1 ranged from 1.1 to 6.3 1 BTPS. Variability when expressed as absolute change was similar at all levels of FEV1, so that, when expressed as percentage change, variability decreased with increasing FEV1. Smoking habits did not appear to affect variability but activity before the test did. On the basis of these results an absolute change in FEV1 of 190 ml would be necessary for 95% confidence that the change in FEV1 occurred other than by chance in any one individual. This suggests that the absolute change in FEV1 might be a more reliable criterion than percentage change when distinguishing between natural variability and a response to inhalation of bronchodilators.
对54名健康的医院员工和13名限制性肺疾病患者测定了20分钟内一秒用力呼气量（FEV1）的自然变异性。初始FEV1范围为1.1至6.3升BTPS。当以绝对变化表示时，FEV1各水平的变异性相似，因此，当以百分比变化表示时，变异性随FEV1增加而降低。吸烟习惯似乎不影响变异性，但测试前的活动会影响。基于这些结果，FEV1发生190毫升的绝对变化，才能有95%的把握确定FEV1的变化不是偶然发生在任何一个个体身上。这表明，在区分自然变异性和对吸入支气管扩张剂的反应时，FEV1的绝对变化可能比百分比变化更可靠。
