Ina patient with clinical signs of asthma which of the following tests will confirm the diagnosis: (A) Increase in FEV1/FVC, (B) >200 ml increase in FEV1 after Methacholine, (C) Diurnal variation inPEF>20 %, (D) Reduction of FEV1>20% after bronchodilators
Answer is C. Demonstrated outflow obstruction.,: Decreased FEV1 Decreased PEF Decreased FEV1/FVC Ref Harrison 19th edition pg 1675