NAECB Spirometry 4 — Questions and Answers
Question 1: Which reference equation set is currently recommended by ATS/ERS for interpreting spirometry in the U.S. adult population?
- Knudson equations (1983)
- NHANES III equations
- Global Lung Function Initiative (GLI) 2012 equations (Correct answer)
- Hankinson equations (1999) only
Correct answer: Global Lung Function Initiative (GLI) 2012 equations
The GLI 2012 multi-ethnic reference equations are now recommended by ATS/ERS as the preferred reference for spirometry interpretation across all ages.
Question 2: A pediatric patient (age 8) performs spirometry. Which additional consideration applies compared to adult testing?
- Exhalation time requirement is extended to 10 seconds
- Test is not valid for children under 10 years
- Minimum exhalation time is typically 3 seconds, not 6 (Correct answer)
- Back-extrapolation criteria do not apply
Correct answer: Minimum exhalation time is typically 3 seconds, not 6
In children under 10, ATS/ERS guidelines accept a minimum exhalation time of 3 seconds rather than the 6 seconds required for adults.
Question 3: A variable extrathoracic (upper airway) obstruction would produce which flow-volume loop pattern?
- Flattening of the expiratory limb only
- Flattening of the inspiratory limb only (Correct answer)
- Flattening of both inspiratory and expiratory limbs
- Scooping of the expiratory limb
Correct answer: Flattening of the inspiratory limb only
Variable extrathoracic obstruction (e.g., vocal cord dysfunction) causes flattening of the inspiratory limb because the lesion worsens during inspiration.
Question 4: Which of the following would be classified as a contraindication to performing spirometry?
- Mild stable asthma
- Recent myocardial infarction within the past month (Correct answer)
- Controlled hypertension
- Age over 65 years
Correct answer: Recent myocardial infarction within the past month
Recent myocardial infarction (within 1 month) is a relative contraindication due to the risk of increased intrathoracic pressure from forced exhalation.
Question 5: In asthma management, spirometry showing normalization of FEV1/FVC after bronchodilator administration indicates:
- Permanent airway remodeling
- Irreversible obstruction
- Reversible airflow limitation (Correct answer)
- A restrictive component
Correct answer: Reversible airflow limitation
Normalization of FEV1/FVC after bronchodilator confirms reversible airflow limitation, a defining feature of asthma.
Question 6: The lower limit of normal (LLN) for FEV1/FVC is defined as:
- Fixed value of 0.70 for all patients
- 5th percentile of the predicted reference population (Correct answer)
- 10th percentile of the predicted reference population
- Two standard deviations below the mean FVC
Correct answer: 5th percentile of the predicted reference population
The LLN is defined as the 5th percentile of the reference population distribution, which accounts for age-related decline better than a fixed cutoff.
Question 7: When reporting spirometry results, which values should be selected from multiple acceptable maneuvers?
- Average of all acceptable FEV1 and FVC values
- Largest FEV1 and largest FVC, even if from different maneuvers (Correct answer)
- Values from the single best maneuver only
- Median values of all acceptable maneuvers
Correct answer: Largest FEV1 and largest FVC, even if from different maneuvers
ATS/ERS guidelines specify that the largest FEV1 and largest FVC should be reported, even if they come from different acceptable maneuvers.
NAECB Spirometry 4
Which reference equation set is currently recommended by ATS/ERS for interpreting spirometry in the U.S. adult population?