RT Journal Article
SR Electronic
T1 Short term variability in FEV1: relation to pretest activity, level of FEV1, and smoking habits.
JF Thorax
JO Thorax
FD BMJ Publishing Group Ltd and British Thoracic Society
SP 928
OP 932
DO 10.1136/thx.39.12.928
VO 39
IS 12
A1 P M Tweeddale
A1 S Merchant
A1 M Leslie
A1 F Alexander
A1 G J McHardy
YR 1984
UL http://thorax.bmj.com/content/39/12/928.abstract
AB 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.