NAECB Spirometry 5 — Questions and Answers
Question 1: A patient with neuromuscular disease shows reduced FVC in both upright and supine positions with no change in ratio. What pattern is expected?
- Obstructive pattern with bronchodilator response
- Restrictive pattern due to respiratory muscle weakness (Correct answer)
- Mixed obstructive-restrictive pattern
- Normal spirometry with reduced diffusion capacity
Correct answer: Restrictive pattern due to respiratory muscle weakness
Neuromuscular disease impairs respiratory muscles, leading to reduced FVC and a preserved FEV1/FVC ratio — a classic restrictive pattern.
Question 2: Which of the following spirometry findings is most consistent with a mixed obstructive-restrictive pattern?
- Low FEV1/FVC with normal FVC
- Normal FEV1/FVC with reduced FVC
- Low FEV1/FVC with reduced FVC (Correct answer)
- Normal FEV1/FVC with normal FVC
Correct answer: Low FEV1/FVC with reduced FVC
A mixed pattern shows both a low FEV1/FVC ratio (obstruction) and a reduced FVC (restriction), though full classification requires lung volume measurement.
Question 3: For spirometry quality assurance, how often should a 3-liter calibration syringe check be performed at minimum?
- Once per week
- Once per month
- Each day of use (Correct answer)
- Before each patient test
Correct answer: Each day of use
ATS/ERS guidelines recommend that volume calibration be verified each day the spirometer is used to ensure ongoing accuracy.
Question 4: A 45-year-old patient with obesity has FVC at 78% predicted and FEV1/FVC of 0.80. What is the most appropriate next step?
- Administer bronchodilator and repeat
- Report as obstructive pattern
- Consider full lung volume testing to confirm restriction (Correct answer)
- Report as normal spirometry
Correct answer: Consider full lung volume testing to confirm restriction
FVC below the LLN with normal FEV1/FVC suggests restriction, but spirometry alone cannot confirm it — full lung volumes (TLC) are needed to distinguish true restriction from other causes of reduced FVC.
Question 5: Which statement about the Inspiratory Capacity (IC) measured during spirometry is correct?
- IC equals FVC minus ERV
- IC is the volume inhaled from tidal end-expiration to TLC (Correct answer)
- IC cannot be measured with a spirometer
- IC is equivalent to IRV alone
Correct answer: IC is the volume inhaled from tidal end-expiration to TLC
IC is the volume of air that can be inhaled from the end-expiratory resting position (FRC) up to total lung capacity (TLC).
Question 6: A patient stops exhaling during an FVC maneuver after 4 seconds but shows a clear plateau on the volume-time curve. Is this maneuver acceptable?
- No, all adults must exhale for at least 6 seconds
- Yes, if a volume plateau (≤25 mL change over 1 second) is achieved (Correct answer)
- No, exhalation must continue until FEV6 is recorded
- Yes, but only if FEV1 was clearly captured
Correct answer: Yes, if a volume plateau (≤25 mL change over 1 second) is achieved
ATS/ERS guidelines accept an exhalation end when a volume plateau of ≤25 mL over 1 second is observed, even if 6 seconds have not elapsed.
Question 7: In the NAECB exam context, which breathing pattern disorder is characterized by inspiratory stridor and a flattened inspiratory limb on flow-volume loop, often misdiagnosed as asthma?
- Paradoxical vocal fold motion (PVFM) (Correct answer)
- Tracheobronchomalacia
- Epiglottitis
- Subglottic stenosis
Correct answer: Paradoxical vocal fold motion (PVFM)
Paradoxical vocal fold motion (PVFM), also called vocal cord dysfunction, causes inspiratory stridor and a characteristic flattened inspiratory limb, frequently mimicking asthma.
NAECB Spirometry 5
A patient with neuromuscular disease shows reduced FVC in both upright and supine positions with no change in ratio.
What pattern is expected?