Pulmonary function test interpretation MCQs With Answer

Introduction

Pulmonary function tests (PFTs) are essential tools for diagnosing, characterizing, and monitoring respiratory diseases. For M.Pharm students involved in clinical pharmacy practice, interpreting PFTs accurately is crucial for optimizing pharmacotherapy, evaluating bronchodilator response, and distinguishing obstructive, restrictive, and mixed ventilatory defects. This blog focuses on Pulmonary Function Test Interpretation MCQs with answers, designed to deepen conceptual understanding of spirometry, lung volumes, diffusion capacity (DLCO), flow–volume loop patterns, and clinical implications for drug management. The questions emphasize practical interpretation, common pitfalls, and how PFT results guide therapeutic decisions in conditions such as asthma, COPD, and interstitial lung disease.

Q1. In spirometry, which pattern is most consistent with obstructive lung disease?

• Reduced FEV1/FVC ratio with normal or increased TLC
• Normal FEV1/FVC ratio with reduced TLC
• Reduced TLC with normal FEV1/FVC ratio
• Normal spirometry with reduced DLCO

Correct Answer: Reduced FEV1/FVC ratio with normal or increased TLC

Q2. What defines a significant bronchodilator response on spirometry?

• Increase in FEV1 or FVC by ≥12% and ≥200 mL from baseline
• Any increase in FEV1 after bronchodilator
• Increase in FEV1 by ≥8% regardless of volume change
• Decrease in FEV1 by ≥12% after bronchodilator

Correct Answer: Increase in FEV1 or FVC by ≥12% and ≥200 mL from baseline

Q3. A reduced DLCO (diffusing capacity) is most characteristic of which condition?

• Emphysema due to alveolar destruction
• Pure asthma without emphysema
• Obesity-related hypoventilation
• Neuromuscular weakness with normal alveolar-capillary membrane

Correct Answer: Emphysema due to alveolar destruction

Q4. Which flow–volume loop pattern suggests a fixed upper airway obstruction?

• Flattening of both inspiratory and expiratory limbs
• Scooped-out (concave) expiratory limb only
• Prominent inspiratory loop with normal expiratory limb
• Tall narrow loop with normal limbs

Correct Answer: Flattening of both inspiratory and expiratory limbs

Q5. What does an increased residual volume (RV) and increased RV/TLC ratio indicate?

• Air trapping and hyperinflation, commonly seen in obstructive disease
• Reduced lung compliance indicating restriction
• Primary reduction in TLC due to pulmonary fibrosis
• Normal lung mechanics with measurement error

Correct Answer: Air trapping and hyperinflation, commonly seen in obstructive disease

Q6. Which statement about FEF25-75% (forced mid-expiratory flow) is true?

• It is sensitive to small airway obstruction but has greater variability than FEV1
• It is the best single value to stage COPD severity per GOLD
• It primarily reflects inspiratory muscle strength
• Normal values rule out any airway disease

Correct Answer: It is sensitive to small airway obstruction but has greater variability than FEV1

Q7. Which interpretation is most consistent with a restrictive ventilatory defect on PFTs?

• Normal or increased FEV1/FVC with reduced TLC
• Reduced FEV1/FVC with increased TLC
• Normal TLC with reduced DLCO only
• Isolated reduction in FEV1 with normal volumes

Correct Answer: Normal or increased FEV1/FVC with reduced TLC

Q8. In COPD severity grading by GOLD, which FEV1 % predicted corresponds to GOLD stage 3 (severe)?

• FEV1 30%–49% predicted
• FEV1 ≥80% predicted
• FEV1 50%–79% predicted
• FEV1 <30% predicted

Correct Answer: FEV1 30%–49% predicted

Q9. A patient has low FEV1, low FVC, and a normal FEV1/FVC ratio. Which additional test best confirms restriction?

• TLC measured by body plethysmography showing reduced TLC
• Repeat spirometry after bronchodilator
• Peak expiratory flow measurement
• DLCO measurement alone without volumes

Correct Answer: TLC measured by body plethysmography showing reduced TLC

Q10. Which factor can falsely lower measured DLCO and should be corrected for during interpretation?

• Anemia (low hemoglobin)
• Hyperkalemia
• Recent bronchodilator administration
• Elevated body temperature

Correct Answer: Anemia (low hemoglobin)

Q11. When is use of lower limit of normal (LLN) preferred over a fixed FEV1/FVC ratio of 0.70?

• To avoid overdiagnosing obstruction in the elderly and underdiagnosing in younger adults
• Only when DLCO is abnormal
• LLN is never preferred; fixed ratio is standard
• Only in patients with known restrictive disease

Correct Answer: To avoid overdiagnosing obstruction in the elderly and underdiagnosing in younger adults

Q12. Which PFT finding suggests pulmonary vascular disease such as pulmonary hypertension?

• Markedly reduced DLCO with relatively preserved lung volumes
• Increased DLCO with reduced TLC
• High FEV1/FVC with increased RV
• Isolated decreased FEF25-75 with normal DLCO

Correct Answer: Markedly reduced DLCO with relatively preserved lung volumes

Q13. Which statement best describes the methacholine bronchial challenge test?

• It assesses airway hyperresponsiveness and is positive when PC20 meets laboratory-defined threshold
• It measures maximal voluntary ventilation to diagnose restriction
• It is used to quantify DLCO abnormalities
• It replaces bronchodilator testing for reversibility

Correct Answer: It assesses airway hyperresponsiveness and is positive when PC20 meets laboratory-defined threshold

Q14. In an asthmatic patient, which PFT pattern and DLCO are most typical?

• Obstructive spirometry with normal or increased DLCO
• Restrictive spirometry with markedly reduced DLCO
• Normal spirometry with severely reduced DLCO
• Mixed pattern with increased TLC and reduced DLCO

Correct Answer: Obstructive spirometry with normal or increased DLCO

Q15. Why is body plethysmography preferred over helium dilution for measuring lung volumes in severe obstruction?

• Plethysmography measures total thoracic gas including trapped gas, whereas helium dilution underestimates volumes with noncommunicating areas
• Helium dilution overestimates volumes in obstruction
• Plethysmography cannot measure RV accurately
• Helium dilution is contraindicated in bronchiectasis

Correct Answer: Plethysmography measures total thoracic gas including trapped gas, whereas helium dilution underestimates volumes with noncommunicating areas

Q16. Which change in the flow–volume loop is characteristic of small airway disease?

• Early expiratory flow reduction causing a concave (scooped) appearance
• Flattened inspiratory limb only
• Symmetric narrowing of both limbs producing a rectangle
• Increased peak expiratory flow with normal mid-flow

Correct Answer: Early expiratory flow reduction causing a concave (scooped) appearance

Q17. A mixed ventilatory defect is suggested on PFTs by which combination?

• Reduced FEV1/FVC ratio and reduced TLC
• Normal FEV1/FVC ratio with normal TLC
• Increased TLC with increased DLCO
• Reduced DLCO only with normal spirometry

Correct Answer: Reduced FEV1/FVC ratio and reduced TLC

Q18. Which PFT parameter is most useful for monitoring bronchodilator therapy effectiveness in COPD over time?

• Serial FEV1 measurements and symptom correlation
• Single DLCO measurement performed once
• Initial RV measurement only
• Single peak inspiratory flow test once

Correct Answer: Serial FEV1 measurements and symptom correlation

Q19. Which clinical scenario would most likely produce an isolated reduction in DLCO with normal spirometry and lung volumes?

• Early pulmonary vascular disease or emphysema affecting gas transfer
• Pure neuromuscular weakness without parenchymal disease
• Chest wall restriction leading to low TLC
• Acute bronchospasm with airflow limitation

Correct Answer: Early pulmonary vascular disease or emphysema affecting gas transfer

Q20. What is the clinical implication if post-bronchodilator testing shows persistent airflow limitation (no significant reversibility)?

• Finding supports COPD or fixed airflow obstruction rather than fully reversible asthma
• Confirms absence of any obstructive lung disease
• Indicates only poor effort during testing
• Suggests contamination of test gases and requires repeat DLCO

Correct Answer: Finding supports COPD or fixed airflow obstruction rather than fully reversible asthma

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