RPFT RPFT Spirometry Technique & Maneuver Acceptability 2 — Questions and Answers
Question 1: What patient instruction is most important immediately before performing a maximal inspiratory maneuver for MIP (PImax) testing?
- Exhale completely to residual volume before inhaling maximally (Correct answer)
- Inspire to TLC before performing the maneuver
- Breathe normally for 30 seconds to reach steady state
- Hold breath at FRC for 3 seconds before inhaling
Correct answer: Exhale completely to residual volume before inhaling maximally
MIP is measured from residual volume (RV) because lung mechanics at RV provide the greatest mechanical advantage for inspiratory muscles.
Question 2: A slow vital capacity (SVC) is larger than the FVC in a patient with COPD. What does this finding indicate?
- Air trapping causes dynamic airway collapse during forced exhalation, reducing FVC (Correct answer)
- The patient performed a submaximal FVC maneuver
- The spirometer overestimates SVC due to calibration error
- The patient has a restrictive pattern superimposed on obstruction
Correct answer: Air trapping causes dynamic airway collapse during forced exhalation, reducing FVC
In obstructive disease, forced expiration causes dynamic collapse of airways, trapping air and yielding a lower FVC than the more slowly measured SVC.
Question 3: During a forced vital capacity maneuver, what does a 'notch' or dip on the descending limb of the flow-volume loop suggest?
- Upper airway obstruction or glottic closure during exhalation (Correct answer)
- Normal variation in healthy patients
- Calibration error in the flow sensor
- Restrictive lung disease
Correct answer: Upper airway obstruction or glottic closure during exhalation
A mid-expiratory notch typically indicates variable upper airway obstruction, such as vocal cord dysfunction or tracheal lesion causing intermittent flow interruption.
Question 4: Which spirometric index is most sensitive for detecting early small airways disease?
- FEF25-75% (mid-maximal expiratory flow) (Correct answer)
- FEV1
- FVC
- PEF (peak expiratory flow)
Correct answer: FEF25-75% (mid-maximal expiratory flow)
FEF25-75% reflects flow in the effort-independent portion of exhalation driven by small airway recoil and is the earliest spirometric marker of peripheral airway disease.
Question 5: An FEV1/FVC ratio of 0.65 in a 68-year-old patient is below the predicted value of 0.74. What is the correct interpretation using ATS/ERS criteria?
- Obstruction is present because the ratio is below the lower limit of normal (LLN) (Correct answer)
- Normal aging, because FEV1/FVC below 0.70 is always expected in elderly patients
- Restriction, because FVC is reduced
- Inconclusive without a bronchodilator test
Correct answer: Obstruction is present because the ratio is below the lower limit of normal (LLN)
ATS/ERS guidelines recommend using the LLN (5th percentile of predicted) rather than a fixed 0.70 cutoff to avoid over-diagnosing obstruction in the elderly.
Question 6: What is the correct sequence of steps for performing a bronchodilator responsiveness test?
- Baseline spirometry → administer bronchodilator → wait 15–20 minutes → repeat spirometry (Correct answer)
- Administer bronchodilator → wait 5 minutes → perform spirometry only once
- Baseline spirometry → administer bronchodilator → immediate repeat spirometry
- Perform spirometry → administer corticosteroid → repeat after 24 hours
Correct answer: Baseline spirometry → administer bronchodilator → wait 15–20 minutes → repeat spirometry
Post-bronchodilator spirometry should be performed 15–20 minutes after administering a short-acting beta2-agonist to allow peak bronchodilation.
RPFT RPFT Spirometry Technique & Maneuver Acceptability 2
What patient instruction is most important immediately before performing a maximal inspiratory maneuver for MIP (PImax) testing?