NBRC Pulmonary Function Testing 2

Question 1

The flow-volume loop in a patient with a fixed upper airway obstruction shows:

Accepted Answer

Flattening of both the inspiratory and expiratory limbs

Answer

Fixed upper airway obstructions (such as tracheal stenosis) truncate both inspiratory and expiratory flows equally, producing a flattened box-like loop.

Question 2

A variable extrathoracic obstruction (e.g., vocal cord dysfunction during inspiration) flattens which portion of the flow-volume loop?

Accepted Answer

Inspiratory limb

Answer

Variable extrathoracic obstructions worsen during inspiration because negative pressure draws the obstruction into the airway, flattening the inspiratory limb.

Question 3

The maximum voluntary ventilation (MVV) test measures:

Accepted Answer

The maximum volume breathed in and out over 12–15 seconds, extrapolated to one minute

Answer

MVV assesses the maximum minute ventilation achievable with maximal effort, reflecting overall ventilatory capacity including respiratory muscle strength and airway patency.

Question 4

Which PFT finding is most consistent with pulmonary fibrosis?

Accepted Answer

Reduced TLC, reduced FVC, normal or elevated FEV1/FVC, reduced DLCO

Answer

Pulmonary fibrosis causes restrictive physiology with reduced TLC and FVC, elevated FEV1/FVC ratio, and reduced DLCO due to loss of alveolar-capillary surface.

Question 5

Nitrogen washout and helium dilution are techniques used to measure:

Accepted Answer

Functional residual capacity (FRC)

Answer

Both nitrogen washout and helium dilution techniques measure FRC by using inert tracer gases to calculate the volume of gas in communication with the open airways.

NBRC - National Board for Respiratory Care Practice Test

NBRC - National Board for Respiratory Care Practice Test

NBRC Pulmonary Function Testing 2