A normal Vital Capacity is approximately what value?

A normal Vital Capacity is approximately what value?

• A. 3.2 L
• B. 4.8 L or 80% of predicted or higher
• C. 6.0 L
• D. 4.0 L

Answer: (B)

Vital capacity is the maximum amount of air a person can exhale after a deep, maximal inhalation, reflecting the combined capacity of the lungs and the surrounding muscles. In healthy adults, this value averages about 4.8 liters, though it varies with body size, age, and sex. Clinically, a vital capacity that is at least 80% of the predicted value—or about 4.8 liters in many adults—is considered normal. That’s why this option best fits the typical reference range. Values well below this threshold, such as around 3.2 liters, are generally not normal for a healthy adult, while values like 6.0 liters exceed the common normal range. A value of 4.0 liters might be acceptable for some individuals, but the standard NBRC reference emphasizes the 4.8 L or 80% of predicted threshold as the typical normal.

Vital capacity is the maximum amount of air a person can exhale after a deep, maximal inhalation, reflecting the combined capacity of the lungs and the surrounding muscles. In healthy adults, this value averages about 4.8 liters, though it varies with body size, age, and sex. Clinically, a vital capacity that is at least 80% of the predicted value—or about 4.8 liters in many adults—is considered normal. That’s why this option best fits the typical reference range. Values well below this threshold, such as around 3.2 liters, are generally not normal for a healthy adult, while values like 6.0 liters exceed the common normal range. A value of 4.0 liters might be acceptable for some individuals, but the standard NBRC reference emphasizes the 4.8 L or 80% of predicted threshold as the typical normal.