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

Obstructive lung disease

Answer

Mixed obstructive-restrictive disease

Answer

Normal variation

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

Low TLC, low RV, normal RV/TLC ratio

Answer

Normal TLC, low FRC, low RV

Answer

Low TLC, high RV, normal FRC

Question 3

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

Accepted Answer

Moderately reduced

Answer

Mildly reduced

Answer

Severely reduced

Answer

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

COPD with emphysema

Answer

Idiopathic pulmonary fibrosis

Answer

Pulmonary embolism

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

Helium is absorbed by bullous tissue

Answer

Bullae increase airway resistance and reduce helium mixing

Answer

The patient cannot achieve a valid FRC starting point

Question 6

When interpreting lung volumes, which of the following isolated findings would suggest neuromuscular disease rather than parenchymal restriction?

Accepted Answer

Low TLC with disproportionately elevated RV and low maximal inspiratory pressure (MIP)

Answer

Low TLC with disproportionately low RV

Answer

Normal TLC with elevated RV

Answer

Elevated TLC with low DLCO

Question 7

After completing a lung volume measurement by plethysmography, the technologist notices the FRC value is much higher than the VC-derived measurements suggest. The most appropriate next step is:

Accepted Answer

Check for mouth leaks, panting frequency errors, or shutter timing artifacts and repeat if needed

Answer

Report the plethysmography result without further action

Answer

Switch to helium dilution and average both results

Answer

Add 500 mL to account for equipment dead space