Houghton CM, Woodcock AA, Singh D. A comparison of lung function methods for assessing dose-response effects of salbutamol.
Br J Clin Pharmacol 2004;
58:134-41. [PMID:
15255795 PMCID:
PMC1884595 DOI:
10.1111/j.1365-2125.2004.02105.x]
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Abstract
Pulmonary function methods which are able to detect small pharmacological effects may be useful for assessing the full dose-response curve of bronchodilatators. We compared the ability of impulse oscillometry (R5, R20, X5, RF), plethysmography (sGaw) and spirometry [forced expiratory volume in 1 s (FEV(1)), maximal mid expiratory flow rate (MMEF)] to measure the dose-response effects of salbutamol in 12 healthy subjects, 12 mild asthmatics (mean FEV(1) 96% predicted) and 12 moderate asthmatics (mean FEV(1) 63% predicted). The techniques were performed twice to assess variability. Then salbutamol 10, 20, 100, 200 and 800 microg was administered. The sensitivity of the methods were compared by determining the lowest dose that caused changes greater than variability. In healthy subjects significant changes (p < or = 0.05) were observed only in FEV(1) (4.1%) and MMEF (14.6%) at 100 microg and sGaw (25.6%) and R20 (8.3%) at 200 microg. In mild asthmatics significant changes were observed in sGaw (15.9%) at 10 microg, X5 (23%), RF (20.3%) and MMEF (15.7%) at 20 microg, R5 (13.9%) and R20 (9.4%) at 100 microg and FEV(1) (7.1%) at 200 microg. All measurements except R20 demonstrated significant changes at 10 micro g in moderate asthmatics. The most sensitive test for assessing bronchodilatation is different in healthy subjects and asthmatics, and varies with severity of airflow obstruction.
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