Effects of spontaneous FEV1 fluctuation on airway reversibility estimation.
Assessment of bronchodilator responsiveness is currently based on criteria derived from population studies, which provide information on the intrasubject variability of forced expiratory volume in one second (FEV1). These criteria themselves, however, differ from each other; and confusion exists on the best way of expressing reversibility. The aims of this study were to measure spontaneous FEV1 variability individually, and to see its impact on the response to salbutamol. Fifty patients with different types and degrees of chronic airflow obstruction were included in the study. FEV1 was measured twice, with an interval of 20 min, in order to assess spontaneous variability. Spirometry was repeated following salbutamol inhalation, and two estimates of reversibility were obtained using the two FEV1 measurements obtained at baseline. Strong correlations were found between the two estimates, and the mean of the differences between the two reversibility estimates was 65.40 +/- 65.68 ml, when expressed in absolute terms. FEV1 responses to salbutamol were superior to the spontaneous variation in FEV1 in 48 (96%) of the patients. Linear regression analysis revealed that there was a highly significant correlation between the baseline FEV1 and the response to salbutamol (r = 0.50 and 0.43, for the first and the second estimates, respectively). These results suggest that the decision on reversibility should not be based on distinct cut-off levels, but rather should be assessed individually, as intrasubject variability seems to be almost always less than the patient's response to bronchodilators.
Güçlü
G
G
Dept of Chest Diseases, Faculty of Medicine, Ege University, Izmir, Turkey.
Sayiner
A
A
D000420:Albuterol / Q000494:pharmacology; D001980:Bronchi / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D015203:Reproducibility of Results
D000420:Albuterol