Spirometry Flashcards

A patient with neuromuscular disease shows reduced FVC in both upright and supine positions with no change in ratio. What pattern is expected?

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.

Which of the following spirometry findings is most consistent with a mixed obstructive-restrictive pattern?

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.

For spirometry quality assurance, how often should a 3-liter calibration syringe check be performed at minimum?

Answer: Each day of use

ATS/ERS guidelines recommend that volume calibration be verified each day the spirometer is used to ensure ongoing accuracy.

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?

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.

Which statement about the Inspiratory Capacity (IC) measured during spirometry is 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).

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?

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.

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?

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.