Measurement of Reversibility of Airways Obstruction: which Parameters to Use?

Abstract

Maximum expiratory flow-volume (MEFV) curves recorded before and after salbutamol inhalation on 100 patients with various lung diseases were studied. Improvement was found to occur more frequently in MEF₅₀, FEF_25-75, FVC and MEF₂₅, than in FEV₁, FEV₁/FVC%, or MTT. If improvement in only one of the first four parameters was taken as a measure of reversibility of airways obstruction, many cases showing improvement in the others were missed. Improvement in any of the last three parameters was rarely missed if improvement in any of the first four was present. It was concluded that there is no single best measurement for assessment of bronchodilator response. FVC, FEF_25-75, MEF₅₀ and MEF₂₅ should all be measured. A flow-volume record of forced expiration from which all these measurements can be derived would therefore be preferable for this purpose to the time-volume spirometer record from which only FVC and FEF_25-75 can be determined.

Reversibility Test in the Early Stages of Bronchial Asthma

“…The impairment of only expiratory flows (MEF) may be indicative of a pulmonary obstructive disease in its early stages or located in limited districts of the airways (14), so that the reduced flows may be considered to be an indication for carrying out the reversibility test. However, it is important in making functional assessments to consider all the parameters with their interpretative limits (17,18). In our study, of 73 pts with an FEV 1 increase after bronchodilator !…”