FEF 200-1200 measures flow in which portion of the airways?

FEF 200-1200 measures flow in which portion of the airways?

• A. Small airways resistance
• B. Oxygen transport
• C. Large airways flow
• D. Diffusion capacity

Answer: (C)

FEF200-1200 is the average expiratory flow from 200 mL to 1,200 mL of the forced vital capacity. This early to mid portion of expiration is mainly governed by the large airways—the trachea and main bronchi—so it reflects large airway flow. Small airways contribute more to the later part of expiration, which is why other measures like FEF25-75% are used to assess small airway function. Diffusion capacity and O2 transport are not what this flow range directly evaluates.

FEF200-1200 is the average expiratory flow from 200 mL to 1,200 mL of the forced vital capacity. This early to mid portion of expiration is mainly governed by the large airways—the trachea and main bronchi—so it reflects large airway flow. Small airways contribute more to the later part of expiration, which is why other measures like FEF25-75% are used to assess small airway function. Diffusion capacity and O2 transport are not what this flow range directly evaluates.