Final answer:
The normal average range of FEV1 varies by individual characteristics but typically falls between 80% and 120% of the predicted value. FEV1 is a key measurement from spirometry tests and is used alongside the FEV1/FVC ratio to diagnose lung diseases.
Step-by-step explanation:
The normal average range of FEV1, or forced expiratory volume in one second, varies among individuals depending on multiple factors including age, sex, height, and ethnicity. Generally, normal FEV1 values are expected to be between approximately 80% and 120% of the predicted value for a healthy person of the same demographic characteristics.
FEV1 is an important measurement taken during spirometry, which is a common pulmonary function test used to assess lung function. A decline in FEV1 can indicate the presence of an obstructive lung disease such as asthma, where there is an increased resistance to airflow, while restrictive lung diseases, characterized by reduced lung volumes, often show a normal or only slightly reduced FEV1. The FEV1/FVC ratio, which compares FEV1 to the total amount of air that can be forcibly exhaled (forced vital capacity or FVC), is crucial in the diagnosis of different types of lung disease.