RRT Pulmonary Function Testing Flashcards
6 cards from real RRT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 RRT Pulmonary Function Testing flashcards as text
Which flow-volume loop pattern is characteristic of a fixed upper airway obstruction?
Answer: Flattening of both inspiratory and expiratory limbs
Fixed upper airway obstruction (e.g., tracheal stenosis) produces plateauing (flattening) of both the inspiratory and expiratory limbs of the flow-volume loop.
What does the term 'air trapping' refer to in pulmonary function testing?
Answer: Elevated RV and RV/TLC ratio indicating incomplete exhalation
Air trapping is diagnosed by an elevated RV and increased RV/TLC ratio (>35%), reflecting incomplete emptying of alveoli in obstructive diseases.
Which pulmonary function test measurement best reflects small airway function?
Answer: FEF 25–75%
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.
In body plethysmography, what does functional residual capacity (FRC) represent?
Answer: Volume of air in the lungs at the end of a normal expiration
FRC is the equilibrium volume of the lungs after passive expiration, where elastic recoil of the lungs balances outward chest wall recoil.
A patient with pulmonary fibrosis would most likely show which spirometry result?
Answer: Reduced FVC, reduced FEV1, normal or elevated FEV1/FVC ratio
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.
What is the purpose of performing the nitrogen washout test?
Answer: Measure lung volumes including FRC when a body box is unavailable
The nitrogen washout test measures FRC by diluting resident nitrogen with 100% oxygen, calculating the original volume from the exhaled nitrogen concentration.