NBRC Pulmonary Function Testing 1 — Questions and Answers
Question 1: Spirometry is primarily used to detect and quantify:
- Gas transfer abnormalities
- Obstructive and restrictive ventilatory defects (Correct answer)
- Pulmonary vascular resistance
- Lung perfusion abnormalities
Correct answer: Obstructive and restrictive ventilatory defects
Spirometry measures airflow and lung volumes, allowing classification of ventilatory defects as obstructive, restrictive, or mixed.
Question 2: An FEV1/FVC ratio below 70% (or below the lower limit of normal) indicates:
- Restrictive lung disease
- Obstructive lung disease (Correct answer)
- Normal lung function
- Diffusion impairment
Correct answer: Obstructive lung disease
A reduced FEV1/FVC ratio is the hallmark of obstructive lung disease, indicating impaired expiratory airflow relative to total lung capacity.
Question 3: In restrictive lung disease, spirometry typically shows:
- Reduced FEV1/FVC ratio with preserved FVC
- Proportionally reduced FEV1 and FVC with a normal or elevated FEV1/FVC ratio (Correct answer)
- Increased total lung capacity
- Elevated residual volume
Correct answer: Proportionally reduced FEV1 and FVC with a normal or elevated FEV1/FVC ratio
Restriction reduces overall lung volumes including FVC, but because both FEV1 and FVC decrease proportionally, the FEV1/FVC ratio is preserved or elevated.
Question 4: The DLCO (diffusing capacity for carbon monoxide) is reduced in which condition?
- Asthma
- Obesity
- Emphysema (Correct answer)
- Neuromuscular weakness
Correct answer: Emphysema
Emphysema destroys alveolar walls and pulmonary capillaries, reducing the surface area available for gas diffusion and lowering DLCO.
Question 5: Body plethysmography is used to measure which lung volume that spirometry cannot directly assess?
- Tidal volume
- Inspiratory reserve volume
- Residual volume (Correct answer)
- Expiratory reserve volume
Correct answer: Residual volume
Residual volume (RV) cannot be measured by spirometry because it remains in the lungs after maximal exhalation; body plethysmography or gas dilution techniques are required.
Question 6: Post-bronchodilator testing showing ≥12% and ≥200 mL improvement in FEV1 indicates:
- Fixed airflow obstruction
- Significant bronchodilator reversibility (consistent with asthma) (Correct answer)
- Restrictive physiology
- Normal baseline spirometry
Correct answer: Significant bronchodilator reversibility (consistent with asthma)
A 12% and 200 mL improvement in FEV1 after bronchodilator is the ATS/ERS criterion for significant reversibility, supporting an asthma diagnosis.
NBRC Pulmonary Function Testing 1
Spirometry is primarily used to detect and quantify: