RPFT Lung Volume Measurement & Diffusing Capacity 3

Question 1

A patient's TLC is 65% of predicted and RV is 60% of predicted, with proportional reductions in all lung volumes. This pattern is most consistent with:

Accepted Answer

Restrictive lung disease

Answer

A proportional reduction in all lung volumes (TLC < 80% predicted) without disproportionate RV elevation defines a restrictive pattern, indicating reduced lung or chest wall capacity.

Question 2

In a patient with severe emphysema, which combination of lung volume findings is most expected?

Accepted Answer

High TLC, high RV, elevated RV/TLC ratio

Answer

Emphysema causes hyperinflation with increased TLC and severe air trapping with disproportionately elevated RV, resulting in a high RV/TLC ratio.

Question 3

A DLCO reported as 55% of predicted is classified as:

Accepted Answer

Moderately reduced

Answer

Per ATS/ERS guidelines, DLCO 40–60% predicted is classified as moderately reduced; below 40% is severely reduced and above 70% is normal.

Question 4

A patient has an obstructive pattern on spirometry with a markedly elevated DLCO. Which diagnosis should be considered?

Accepted Answer

Asthma or pulmonary hemorrhage

Answer

Polycythemia, pulmonary hemorrhage, or active bleeding into the lungs provides additional hemoglobin for CO binding, elevating DLCO; asthma alone may also show mildly elevated or normal DLCO.

Question 5

Which of the following best explains why helium dilution FRC may be falsely LOW in a patient with a large pulmonary bulla?

Accepted Answer

The bulla does not communicate with ventilated airways, so helium never reaches it

Answer

Bullae are air-filled spaces isolated from the ventilated airway tree; helium cannot enter them during the closed-circuit maneuver, causing an underestimate of true FRC.

RPFT - Registered Pulmonary Function Technologist Practice Test

RPFT - Registered Pulmonary Function Technologist Practice Test

RPFT Lung Volume Measurement & Diffusing Capacity 3