Question

What should you first look at when looking at the breakdown of PFTs?

A) The diffusing capacity
B) Forced vital capacity (FVC)
C) Peak expiratory flow rate (PEFR)
D) Total lung capacity (TLC)

Answer 1

The forced vital capacity (FVC) is the initial and primary value to look at when evaluating pulmonary function tests, as it helps determine lung functionality and potential diseases when assessed alongside the FEV1/FVC ratio.

Step-by-step explanation:

When analyzing pulmonary function tests (PFTs), the first value one should look at is the forced vital capacity (FVC). FVC is an essential parameter that indicates the total amount of air that can be forcibly exhaled after taking the deepest breath possible. The FEV1/FVC ratio helps diagnose lung diseases, as it measures the forced expiratory volume (FEV1), which is the amount of air that can be forced out of the lungs in one second.

A high FEV1/FVC ratio suggests non-compliant lungs characteristic of restrictive lung diseases like fibrosis, where lungs are stiff. Conversely, a low FEV1/FVC ratio indicates obstructive lung diseases, such as asthma, where there is increased resistance in the airways making it difficult for air to be expelled. Therefore, the FVC and the FEV1/FVC ratio together provide crucial information regarding lung function and potential pathology.