PFT Interpretation Quiz
Questions: 16 · 10 minutes
1. What is forced vital capacity, or FVC?
The total volume exhaled during a maximal forced expiratory maneuver
The amount of air left after the patient exhales as far as possible
The volume exhaled only during the maneuver's first second
The amount of air moved during one ordinary resting breath
2. A flow-volume loop has a relatively flattened inspiratory limb while the expiratory limb is comparatively preserved. Which pattern should be considered?
Variable extrathoracic upper-airway obstruction
Fixed upper-airway obstruction
Variable intrathoracic obstruction
Confirmed pulmonary fibrosis
3. What aspect of pulmonary function does DLCO primarily assess?
Total volume exhaled during the first second
Strength of the respiratory muscles during forced exhalation
Transfer of gas from the alveoli into pulmonary capillary blood
Resistance in the large airways during inspiration only
4. Spirometry shows a low FVC but a preserved FEV1/FVC ratio. What is the most appropriate next step for determining whether restriction is present?
Diagnose restriction from spirometry alone
Use DLCO alone to calculate total lung capacity
Repeat only the peak expiratory flow measurement
Measure lung volumes, including total lung capacity
5. A patient has a reduced FEV1, an FEV1/FVC ratio below the lower limit of normal, and an FVC within the reference range. What is the primary pattern?
Mixed obstructive and restrictive defect
Confirmed restrictive ventilatory defect
Obstructive ventilatory pattern
Isolated gas-transfer impairment
6. A flow-volume loop shows flattening of both the inspiratory and expiratory limbs. Which pattern does this most strongly suggest?
Typical small-airway obstruction only
Fixed upper-airway obstruction
Isolated restriction with no airway involvement
Normal variation caused solely by older age
7. Which spirometry finding most directly supports an obstructive ventilatory pattern?
An increased residual volume by itself
A reduced FVC with a preserved FEV1/FVC ratio
An FEV1/FVC ratio below the appropriate lower limit of normal
A reduced DLCO with otherwise normal spirometry
8. A patient's current FEV1 is unexpectedly lower than on a previous study. What should be checked before concluding that lung function has truly worsened?
Whether the current FEV1/FVC ratio is exactly 0.70
Test quality, effort, testing conditions, and comparability with the previous study
Whether the current DLCO is above 80% predicted
Whether the patient has ever used an inhaler
9. Why is the lower limit of normal or a reference-based z-score generally more informative than using 80% predicted as a universal cutoff?
It accounts for expected variation within an appropriate reference population
It makes patient age and biological sex irrelevant
It eliminates the need to consider test quality
It guarantees that every abnormal result identifies a specific disease
10. Which measurement is required to confirm a restrictive ventilatory defect?
Peak expiratory flow
FEV1 alone
Inspiratory capacity
Total lung capacity
11. Several spirometry attempts show hesitant starts, early termination, and poor repeatability. What should happen before the numerical pattern is interpreted?
Average all attempts and report the result as definitive
Review acceptability and repeatability and obtain better maneuvers if possible
Classify the pattern from the predicted percentages alone
Use the attempt with the highest FEV1/FVC ratio, regardless of quality
12. What does FEV1 measure during spirometry?
The volume inhaled during the first second after a normal exhalation
The total air remaining in the lungs after maximal exhalation
The greatest flow reached at any point during quiet breathing
The volume forcibly exhaled in the first second after a full inhalation
13. A patient has a reduced total lung capacity, preserved FEV1/FVC ratio, and normal DLCO. Which general explanation should be considered?
A fixed upper-airway obstruction is confirmed
An extrapulmonary restrictive process, such as chest-wall or neuromuscular limitation
Emphysema is the only likely cause
The total lung capacity must be disregarded because DLCO is normal
14. A technically acceptable lung-volume test shows a total lung capacity below the lower limit of normal. How should this finding be classified?
A restrictive ventilatory defect
Obstruction regardless of spirometry
Air trapping without restriction
A normal variant whenever residual volume is preserved
15. A patient has an obstructive spirometry pattern and a reduced DLCO. Which interpretation is most appropriate?
The combination proves asthma
DLCO cannot provide useful information when obstruction is present
The low DLCO confirms a restrictive defect
The pattern suggests associated gas-transfer impairment, as may occur with emphysema, but requires clinical correlation
16. After a bronchodilator, a patient's FEV1 increases substantially beyond expected testing variability. What can be concluded from this finding alone?
The patient definitely has asthma
The patient cannot have chronic airflow obstruction
There is a significant bronchodilator response, but the result alone does not establish a diagnosis
The pre-bronchodilator maneuver must have been invalid