RRT RRT Pulmonary Function Testing 2

Question 1

Which flow-volume loop pattern is characteristic of a fixed upper airway obstruction?

Accepted Answer

Flattening of both inspiratory and expiratory limbs

Answer

Fixed upper airway obstruction (e.g., tracheal stenosis) produces plateauing (flattening) of both the inspiratory and expiratory limbs of the flow-volume loop.

Question 2

What does the term 'air trapping' refer to in pulmonary function testing?

Accepted Answer

Elevated RV and RV/TLC ratio indicating incomplete exhalation

Answer

Air trapping is diagnosed by an elevated RV and increased RV/TLC ratio (>35%), reflecting incomplete emptying of alveoli in obstructive diseases.

Question 3

Which pulmonary function test measurement best reflects small airway function?

Accepted Answer

FEF 25–75%

Answer

FEF 25–75% (forced expiratory flow between 25% and 75% of FVC) reflects small to medium airway function and may show obstruction before FEV1 changes.

Question 4

In body plethysmography, what does functional residual capacity (FRC) represent?

Accepted Answer

Volume of air in the lungs at the end of a normal expiration

Answer

FRC is the equilibrium volume of the lungs after passive expiration, where elastic recoil of the lungs balances outward chest wall recoil.

Question 5

A patient with pulmonary fibrosis would most likely show which spirometry result?

Accepted Answer

Reduced FVC, reduced FEV1, normal or elevated FEV1/FVC ratio

Answer

Pulmonary fibrosis causes a restrictive pattern with reduced FVC and FEV1, but FEV1/FVC is preserved or increased because fibrosis stiffens the lung aiding forced expiration.

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RRT RRT Pulmonary Function Testing 2