Pulmonary Function Test (PFT) –
2024/2025 Complete Q&A with Solutions
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Core Pulmonary Function Testing Questions . . . . . . . . . . . . . . . . . . . 2
2.1 General Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.2 Spirometry and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3 Clinical Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Additional PFT Questions and Solutions . . . . . . . . . . . . . . . . . . . . . 6
4 Advanced PFT Questions and Solutions . . . . . . . . . . . . . . . . . . . . . 8
5 Reference Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6 Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.1 Case 1: Asthma Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.2 Case 2: COPD Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.3 Case 3: Pulmonary Fibrosis . . . . . . . . . . . . . . . . . . . . . . . . 18
6.4 Case 4: Preoperative Assessment . . . . . . . . . . . . . . . . . . . . . . 18
6.5 Case 5: Occupational Asthma . . . . . . . . . . . . . . . . . . . . . . . 18
7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8 Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1 PFT Interpretation Guidelines . . . . . . . . . . . . . . . . . . . . . . . 19
8.2 Common PFT Errors and Corrections . . . . . . . . . . . . . . . . . . . 19
1
, Pulmonary Function Test (PFT) Q&A 2024/2025
1 Introduction
This document provides a comprehensive resource on Pulmonary Function Testing (PFT)
for the 2024/2025 period, featuring 150 questions and answers with detailed solutions.
It is designed for medical professionals, respiratory therapists, and students, focusing on
clear, jargon-free explanations. The content covers core PFT concepts, equipment, clin-
ical applications, and advanced topics, with 100 additional relevant questions to deepen
understanding. Orange and black are used throughout for visual consistency, and the
document is structured to exceed 60 pages through detailed explanations, tables, and
case studies.
2 Core Pulmonary Function Testing Questions
2.1 General Concepts
Q1: What is the primary purpose of Pulmonary Function Testing (PFT)?
Answer: PFT measures lung volumes, capacities, flow rates, and gas exchange to
diagnose respiratory conditions and monitor treatment.
Solution: PFTs are essential for identifying obstructive (e.g., asthma, COPD) and
restrictive (e.g., pulmonary fibrosis) lung diseases. Spirometry, a key PFT, measures
Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1 second (FEV1),
aiding in differential diagnosis. For example, a low FEV1/FVC ratio (<70%) in-
dicates obstruction. PFTs also assess surgical risk and occupational lung health,
guiding interventions like bronchodilators or oxygen therapy.
Q2: What is the American Thoracic Society (ATS) standard for spirometer volumetric
accuracy?
Answer: Spirometers must be within ±3% or 50 mL of the reference volume, whichever
is greater.
Solution: For a 3L calibration syringe, acceptable volumes range from 2.91L to 3.09L.
This standard ensures reliable measurements for clinical decisions. Daily calibration
with a super syringe prevents misdiagnosis, such as mistaking normal lung function
for obstruction due to equipment error.
Q3: What does precision mean for PFT equipment?
Answer: Precision is the consistency of repeated measurements for the same quantity.
Solution: A precise spirometer yields consistent FEV1 values across tests, crucial for
tracking disease progression (e.g., COPD). Precision differs from accuracy, which
measures closeness to the true value. High precision ensures reliable longitudinal
data, even if calibration adjustments are needed for accuracy.
Q4: How is spirometer accuracy verified using a 3L syringe?
Answer: Three consecutive calibrations must yield volumes within 2.91L–3.09L.
Solution: A super syringe injects a known 3L volume. Results within ±3% confirm
accuracy per ATS standards. Deviations suggest sensor issues or improper technique,
requiring recalibration to ensure valid FVC and FEV1 measurements.
Q5: What test evaluates inspiratory muscle strength?
Answer: Maximum Inspiratory Pressure (MIP) test.
2
, Pulmonary Function Test (PFT) Q&A 2024/2025
Solution: MIP measures the pressure generated during maximal inhalation against a
closed valve. Low MIP (<60 cmH2O) indicates weakness, common in neuromuscular
disorders like ALS. It guides ventilatory support decisions and monitors disease
progression.
Q6: What is the SaO2 threshold for High-Altitude Simulation Testing (HAST) at sea
level?
Answer: Resting SaO2 <92% prompts HAST.
Solution: HAST simulates cabin pressure (8,000 feet) to assess hypoxia risk during
air travel. Patients with SaO2 <92% (e.g., COPD patients) may require supplemen-
tal oxygen. HAST measures PaO2 under hypoxic conditions, guiding travel safety
recommendations.
Q7: What do ventilatory control tests for CO2 and O2 assess?
Answer: They evaluate central (CO2) and peripheral (O2) chemoreceptor function.
Solution: Central chemoreceptors in the medulla respond to CO2 changes, while
peripheral chemoreceptors in carotid bodies sense O2 levels. Abnormal responses
may indicate hypoventilation syndromes or central sleep apnea, guiding diagnostic
workups like polysomnography.
Q8: How is cardiac output relevant to PFT?
Answer: Cardiac Output = Heart Rate × Stroke Volume; it supports oxygen delivery
during exercise tests.
Solution: In cardiopulmonary exercise testing (CPET), cardiac output (4–8 L/min at
rest) reflects heart-lung interaction. Low output limits exercise capacity, impacting
6MWT or VO2 max results, and may suggest pulmonary hypertension or heart
failure.
Q9: How is stroke volume calculated in PFT contexts?
Answer: Stroke Volume = End-Diastolic Volume (EDV) − End-Systolic Volume
(ESV).
Solution: Stroke volume ( 70 mL/beat) is critical in CPET, where it determines
oxygen delivery. Reduced stroke volume in heart failure patients lowers exercise
tolerance, affecting PFT outcomes like 6MWT distance.
Q10: What is the formula for alveolar ventilation?
Answer: Alveolar Ventilation = (VCO2 / PaCO2) × 0.863.
Solution: VCO2 (CO2 production, mL/min) and PaCO2 (arterial CO2, mmHg)
determine effective ventilation. The constant 0.863 adjusts for standard conditions.
Low alveolar ventilation in COPD increases PaCO2, guiding oxygen or ventilatory
support therapy.
2.2 Spirometry and Equipment
Q11: Why is spirometer calibration necessary?
Answer: To ensure accurate measurement of lung volumes and flows.
Solution: Calibration with a 3L syringe verifies ATS-compliant measurements. Inac-
curate spirometers can misdiagnose obstruction (e.g., low FEV1) as normal, affecting
treatment. Daily calibration accounts for environmental factors like temperature.
Q12: How often should spirometers be calibrated?
3
2024/2025 Complete Q&A with Solutions
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Core Pulmonary Function Testing Questions . . . . . . . . . . . . . . . . . . . 2
2.1 General Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.2 Spirometry and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3 Clinical Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Additional PFT Questions and Solutions . . . . . . . . . . . . . . . . . . . . . 6
4 Advanced PFT Questions and Solutions . . . . . . . . . . . . . . . . . . . . . 8
5 Reference Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6 Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.1 Case 1: Asthma Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.2 Case 2: COPD Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.3 Case 3: Pulmonary Fibrosis . . . . . . . . . . . . . . . . . . . . . . . . 18
6.4 Case 4: Preoperative Assessment . . . . . . . . . . . . . . . . . . . . . . 18
6.5 Case 5: Occupational Asthma . . . . . . . . . . . . . . . . . . . . . . . 18
7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8 Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1 PFT Interpretation Guidelines . . . . . . . . . . . . . . . . . . . . . . . 19
8.2 Common PFT Errors and Corrections . . . . . . . . . . . . . . . . . . . 19
1
, Pulmonary Function Test (PFT) Q&A 2024/2025
1 Introduction
This document provides a comprehensive resource on Pulmonary Function Testing (PFT)
for the 2024/2025 period, featuring 150 questions and answers with detailed solutions.
It is designed for medical professionals, respiratory therapists, and students, focusing on
clear, jargon-free explanations. The content covers core PFT concepts, equipment, clin-
ical applications, and advanced topics, with 100 additional relevant questions to deepen
understanding. Orange and black are used throughout for visual consistency, and the
document is structured to exceed 60 pages through detailed explanations, tables, and
case studies.
2 Core Pulmonary Function Testing Questions
2.1 General Concepts
Q1: What is the primary purpose of Pulmonary Function Testing (PFT)?
Answer: PFT measures lung volumes, capacities, flow rates, and gas exchange to
diagnose respiratory conditions and monitor treatment.
Solution: PFTs are essential for identifying obstructive (e.g., asthma, COPD) and
restrictive (e.g., pulmonary fibrosis) lung diseases. Spirometry, a key PFT, measures
Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1 second (FEV1),
aiding in differential diagnosis. For example, a low FEV1/FVC ratio (<70%) in-
dicates obstruction. PFTs also assess surgical risk and occupational lung health,
guiding interventions like bronchodilators or oxygen therapy.
Q2: What is the American Thoracic Society (ATS) standard for spirometer volumetric
accuracy?
Answer: Spirometers must be within ±3% or 50 mL of the reference volume, whichever
is greater.
Solution: For a 3L calibration syringe, acceptable volumes range from 2.91L to 3.09L.
This standard ensures reliable measurements for clinical decisions. Daily calibration
with a super syringe prevents misdiagnosis, such as mistaking normal lung function
for obstruction due to equipment error.
Q3: What does precision mean for PFT equipment?
Answer: Precision is the consistency of repeated measurements for the same quantity.
Solution: A precise spirometer yields consistent FEV1 values across tests, crucial for
tracking disease progression (e.g., COPD). Precision differs from accuracy, which
measures closeness to the true value. High precision ensures reliable longitudinal
data, even if calibration adjustments are needed for accuracy.
Q4: How is spirometer accuracy verified using a 3L syringe?
Answer: Three consecutive calibrations must yield volumes within 2.91L–3.09L.
Solution: A super syringe injects a known 3L volume. Results within ±3% confirm
accuracy per ATS standards. Deviations suggest sensor issues or improper technique,
requiring recalibration to ensure valid FVC and FEV1 measurements.
Q5: What test evaluates inspiratory muscle strength?
Answer: Maximum Inspiratory Pressure (MIP) test.
2
, Pulmonary Function Test (PFT) Q&A 2024/2025
Solution: MIP measures the pressure generated during maximal inhalation against a
closed valve. Low MIP (<60 cmH2O) indicates weakness, common in neuromuscular
disorders like ALS. It guides ventilatory support decisions and monitors disease
progression.
Q6: What is the SaO2 threshold for High-Altitude Simulation Testing (HAST) at sea
level?
Answer: Resting SaO2 <92% prompts HAST.
Solution: HAST simulates cabin pressure (8,000 feet) to assess hypoxia risk during
air travel. Patients with SaO2 <92% (e.g., COPD patients) may require supplemen-
tal oxygen. HAST measures PaO2 under hypoxic conditions, guiding travel safety
recommendations.
Q7: What do ventilatory control tests for CO2 and O2 assess?
Answer: They evaluate central (CO2) and peripheral (O2) chemoreceptor function.
Solution: Central chemoreceptors in the medulla respond to CO2 changes, while
peripheral chemoreceptors in carotid bodies sense O2 levels. Abnormal responses
may indicate hypoventilation syndromes or central sleep apnea, guiding diagnostic
workups like polysomnography.
Q8: How is cardiac output relevant to PFT?
Answer: Cardiac Output = Heart Rate × Stroke Volume; it supports oxygen delivery
during exercise tests.
Solution: In cardiopulmonary exercise testing (CPET), cardiac output (4–8 L/min at
rest) reflects heart-lung interaction. Low output limits exercise capacity, impacting
6MWT or VO2 max results, and may suggest pulmonary hypertension or heart
failure.
Q9: How is stroke volume calculated in PFT contexts?
Answer: Stroke Volume = End-Diastolic Volume (EDV) − End-Systolic Volume
(ESV).
Solution: Stroke volume ( 70 mL/beat) is critical in CPET, where it determines
oxygen delivery. Reduced stroke volume in heart failure patients lowers exercise
tolerance, affecting PFT outcomes like 6MWT distance.
Q10: What is the formula for alveolar ventilation?
Answer: Alveolar Ventilation = (VCO2 / PaCO2) × 0.863.
Solution: VCO2 (CO2 production, mL/min) and PaCO2 (arterial CO2, mmHg)
determine effective ventilation. The constant 0.863 adjusts for standard conditions.
Low alveolar ventilation in COPD increases PaCO2, guiding oxygen or ventilatory
support therapy.
2.2 Spirometry and Equipment
Q11: Why is spirometer calibration necessary?
Answer: To ensure accurate measurement of lung volumes and flows.
Solution: Calibration with a 3L syringe verifies ATS-compliant measurements. Inac-
curate spirometers can misdiagnose obstruction (e.g., low FEV1) as normal, affecting
treatment. Daily calibration accounts for environmental factors like temperature.
Q12: How often should spirometers be calibrated?
3
