You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Asthma - spirometry features are and explain in detail?
In asthma,FEV will be decreased with decreased FEV1/FVC ratio.RV will be increased due to exaggerated airway closure at low lung volumes,and this elevation of RV reduces FVC.Peak flow meter shows reduced PEF.A diurnal variation in PEF of more than 20% is considered diagnostic of asthma. Reference:Harrison's medicine-18th edition,page no:2094;Davidson's medicine-22nd edition,page no:668.