NAECB Spirometry 3 — Questions and Answers
Question 1: Which spirometry value is the BEST single indicator of the severity of airflow obstruction in COPD?
- FVC % predicted
- FEV1 % predicted (Correct answer)
- PEF % predicted
- FEF25-75% predicted
Correct answer: FEV1 % predicted
FEV1 % predicted is the standard measure used by GOLD guidelines to grade severity of airflow obstruction in COPD.
Question 2: The FEF25-75% (forced expiratory flow from 25% to 75% of FVC) is most sensitive for detecting dysfunction in which airways?
- Large central airways
- Trachea and main bronchi
- Small peripheral airways (Correct answer)
- Alveolar ducts
Correct answer: Small peripheral airways
FEF25-75% reflects flow through small peripheral airways and may be reduced early in obstructive disease before FEV1 declines.
Question 3: A patient performs spirometry and the two largest FVC values differ by more than 150 mL. What does this indicate?
- The test is acceptable but not reproducible (Correct answer)
- The test is unacceptable and should be discarded
- The patient has severe restriction
- The spirometer needs calibration
Correct answer: The test is acceptable but not reproducible
Per ATS/ERS guidelines, if the two largest acceptable FVC values differ by >150 mL, reproducibility criteria are not met, though individual maneuvers may still be acceptable.
Question 4: Which condition would most likely produce a fixed upper airway obstruction pattern on a flow-volume loop?
- Asthma
- Tracheal stenosis (Correct answer)
- Emphysema
- Pulmonary fibrosis
Correct answer: Tracheal stenosis
Tracheal stenosis causes a fixed obstruction that flattens BOTH the inspiratory and expiratory limbs of the flow-volume loop equally.
Question 5: Post-bronchodilator testing shows FEV1 increases by 240 mL and 13% from baseline. How should this be interpreted?
- Not significant; requires 15% change
- Significant bronchodilator response (Correct answer)
- Indeterminate; repeat in 2 weeks
- Significant only if FVC also changes
Correct answer: Significant bronchodilator response
ATS/ERS criteria define a significant bronchodilator response as an increase in FEV1 or FVC of ≥200 mL AND ≥12% from baseline.
Question 6: During spirometry, a patient coughs during the forced exhalation. What is the impact on test acceptability?
- The maneuver is always acceptable if effort was adequate
- The maneuver is acceptable only if cough occurred after 1 second (Correct answer)
- The maneuver is unacceptable regardless of when the cough occurred
- The maneuver is acceptable if FEV1 can still be measured
Correct answer: The maneuver is acceptable only if cough occurred after 1 second
ATS/ERS guidelines state that coughing during the first second of exhalation renders the maneuver unacceptable, as it affects FEV1 measurement.
Question 7: What is the primary purpose of volume calibration verification in spirometry?
- To confirm the patient's lung volumes are normal
- To ensure the spirometer accurately measures volumes (Correct answer)
- To set the predicted normal reference values
- To verify patient effort during testing
Correct answer: To ensure the spirometer accurately measures volumes
Volume calibration verification using a 3-liter syringe confirms the spirometer accurately measures known volumes within ±3.5% error.
NAECB Spirometry 3
Which spirometry value is the BEST single indicator of the severity of airflow obstruction in COPD?