Question: is pefr same as fev1?
Answer: Peak Flow will only measure Peak Expiratory Flow, PEF. ... PEF: Gives highest speed of airflow, but does not determine prescense of disease or severity. So, the direct answer is NO, it does not correlate to FEV1 and should not be used as a substitute for it. PEF is often used to monitor asthma symptoms, not COPD.