pulmo 5 - darkhorse

[ArchivalUser]

Among the following pulmonary function test results, pick those which are the most likely finding in
idiopathic pulmonary fibrosis?

A. Increased total lung capacity (TLC), decreased vital capacity (VC), decreased FEV1/FVC ratio
B. Decreased TLC, decreased VC, decreased residual volume (RV), increased FEV1/FVC ratio, normal
maximum inspiratory pressure (MIP)
C. Decreased TLC, decreased RV, normal FEV1/FVC ratio, decreased MIP
D. Normal TLC, normal RV, normal FEV1/FVC ratio, normal MIP

[ArchivalUser]

C?

[ArchivalUser]

C...........decreased voulmes, decreased MIP

[ArchivalUser]

C.

[ArchivalUser]

C

[ArchivalUser]

The answer is B.


Ventilatory function can be easily measured with lung volume measurement and the FEV1/FVC ratio. A
decreased FEV1/FVC ratio diagnoses obstructive lung disease. Alternatively, low lung volumes,
specifically decreased TLC, and occasionally decreased RV diagnose restrictive lung disease. With
extensive air trapping in obstructive lung disease, TLC is often increased and RV may also be increased.
VC is proportionally decreased. MIP measures respiratory muscle strength and is decreased in patients
with neuromuscular disease. Thus, myasthenia gravis will produce low lung volumes and decreased MIP,
whereas patients with idiopathic pulmonary fibrosis will have normal muscle strength and subsequently a
normal MIP but decreased TLC and RV. In some cases of pulmonary parenchymal restrictive lung
disease, the increase in elastic recoil results in an increased FEV1/FVC ratio. The hallmark of obstructive
lung disease is a decreased FEV1/FVC ratio.