FEV1 normal value is approximately what?

FEV1 normal value is approximately what?

• A. 4.0 L or 80% of predicted or higher
• B. 6.0 L
• C. 3.0 L
• D. 5.0 L

Answer: (A)

FEV1 is the amount of air you can blow out in the first second of a forced exhalation. In healthy adults this value is about 4 liters, though it varies with age, height, sex, and ethnicity. Clinically, we compare the measured FEV1 to the predicted value for that person, and a value of roughly 80% of predicted or higher is considered normal. For an average adult, that roughly corresponds to about 4.0 L. So the best choice reflects both the typical absolute value and the usual percentage of predicted used to define normal function. The other numbers don’t fit because they’re either much higher than what’s normally observed in most adults or clearly lower than what’s considered normal for a healthy individual.

FEV1 is the amount of air you can blow out in the first second of a forced exhalation. In healthy adults this value is about 4 liters, though it varies with age, height, sex, and ethnicity. Clinically, we compare the measured FEV1 to the predicted value for that person, and a value of roughly 80% of predicted or higher is considered normal. For an average adult, that roughly corresponds to about 4.0 L.

So the best choice reflects both the typical absolute value and the usual percentage of predicted used to define normal function. The other numbers don’t fit because they’re either much higher than what’s normally observed in most adults or clearly lower than what’s considered normal for a healthy individual.