Certified Pulmonary Function Technologist (CPFT) Exam 2026:
Professional Certification Practice Examination — Pulmonary
Function Equipment, Calibration, Diagnostic Procedures,
Spirometry, Lung Volumes, Diffusion Testing & Data Interpretation
— 190 Multiple-Choice Questions with Answers & Detailed
Rationales
Question 1
A pulmonary function technologist is preparing a spirometer for daily testing. The device
uses a pneumotachometer. Which calibration procedure is most appropriate before patient
testing begins?
A. Calibrate with a 3-L syringe at three different flow rates
B. Perform a linearity check using a 1-L syringe only
C. Verify calibration with a biological control subject
D. Check the pneumotachometer against a rotameter
Correct Answer: A
Explanation: ATS/ERS standards require daily volume calibration of spirometers using a 3-L
syringe across a range of flows to verify accuracy and linearity. Clinical pearl: Low-flow and
high-flow calibration checks detect flow sensor nonlinearity.
Question 2
A technologist notices that the mouth pressure gauge on a body plethysmograph reads 2 cm
H₂O when the shutter is closed and the patient is not breathing. What is the most likely
cause?
,A. The pressure transducer requires recalibration
B. The patient is generating positive pressure
C. The box door seal is leaking
D. The breathing valve is stuck in the open position
Correct Answer: A
Explanation: A nonzero baseline pressure with a closed shutter and no patient effort
indicates transducer drift requiring recalibration. Best practice: Verify pressure zeroing
before each patient.
Question 3
Which of the following gases requires a dedicated analyzer with a katharometer for
measurement during lung volume testing?
A. Carbon dioxide
B. Helium
C. Nitrogen
D. Carbon monoxide
Correct Answer: B
Explanation: Helium concentration is measured by thermal conductivity (katharometer)
during helium dilution lung volume testing. Clinical pearl: Helium analyzers require regular
calibration with known gas concentrations.
Question 4
,A technologist is setting up equipment for a methacholine challenge test. Which safety item
must be immediately available at the bedside?
A. A 12-lead ECG machine
B. A spirometer with a bacterial filter
C. A short-acting beta-agonist inhaler
D. Supplemental oxygen via nasal cannula
Correct Answer: C
Explanation: A short-acting bronchodilator must be immediately available to reverse severe
bronchoconstriction during bronchoprovocation. Best practice: Confirm emergency
medications and protocols before initiating any challenge.
Question 5
During calibration of a blood gas analyzer, the technologist notes that the pH value for the
low calibrant is outside the acceptable range. What is the most appropriate initial action?
A. Report patient results using the current calibration
B. Repeat calibration with fresh calibrant solutions
C. Adjust the analyzer's internal pH slope manually
D. Perform a two-point calibration using only the high calibrant
Correct Answer: B
Explanation: Out-of-range calibration values often result from expired or contaminated
calibrants; fresh solutions should be tried first. Clinical pearl: Document all calibration
failures and corrective actions.
, Question 6
A technologist is preparing a DLCO system for testing. Which gas mixture is standard for the
single-breath technique?
A. 0.3% CO, 10% He, 21% O₂, balance N₂
B. 0.3% CO, 10% CH₄, 21% O₂, balance N₂
C. 1.0% CO, 5% He, 21% O₂, balance N₂
D. 0.1% CO, 15% Ne, 21% O₂, balance N₂
Correct Answer: A
Explanation: The standard DLCO test gas contains 0.3% CO and 10% helium as the tracer gas
with 21% oxygen. Clinical pearl: Helium allows calculation of alveolar volume from single-
breath dilution.
Question 7
What is the primary purpose of a biological control subject in a pulmonary function
laboratory?
A. To calibrate the spirometer daily
B. To verify that equipment and technique produce stable longitudinal results
C. To establish new predicted reference values
D. To train new technologists in testing procedures
Correct Answer: B
Professional Certification Practice Examination — Pulmonary
Function Equipment, Calibration, Diagnostic Procedures,
Spirometry, Lung Volumes, Diffusion Testing & Data Interpretation
— 190 Multiple-Choice Questions with Answers & Detailed
Rationales
Question 1
A pulmonary function technologist is preparing a spirometer for daily testing. The device
uses a pneumotachometer. Which calibration procedure is most appropriate before patient
testing begins?
A. Calibrate with a 3-L syringe at three different flow rates
B. Perform a linearity check using a 1-L syringe only
C. Verify calibration with a biological control subject
D. Check the pneumotachometer against a rotameter
Correct Answer: A
Explanation: ATS/ERS standards require daily volume calibration of spirometers using a 3-L
syringe across a range of flows to verify accuracy and linearity. Clinical pearl: Low-flow and
high-flow calibration checks detect flow sensor nonlinearity.
Question 2
A technologist notices that the mouth pressure gauge on a body plethysmograph reads 2 cm
H₂O when the shutter is closed and the patient is not breathing. What is the most likely
cause?
,A. The pressure transducer requires recalibration
B. The patient is generating positive pressure
C. The box door seal is leaking
D. The breathing valve is stuck in the open position
Correct Answer: A
Explanation: A nonzero baseline pressure with a closed shutter and no patient effort
indicates transducer drift requiring recalibration. Best practice: Verify pressure zeroing
before each patient.
Question 3
Which of the following gases requires a dedicated analyzer with a katharometer for
measurement during lung volume testing?
A. Carbon dioxide
B. Helium
C. Nitrogen
D. Carbon monoxide
Correct Answer: B
Explanation: Helium concentration is measured by thermal conductivity (katharometer)
during helium dilution lung volume testing. Clinical pearl: Helium analyzers require regular
calibration with known gas concentrations.
Question 4
,A technologist is setting up equipment for a methacholine challenge test. Which safety item
must be immediately available at the bedside?
A. A 12-lead ECG machine
B. A spirometer with a bacterial filter
C. A short-acting beta-agonist inhaler
D. Supplemental oxygen via nasal cannula
Correct Answer: C
Explanation: A short-acting bronchodilator must be immediately available to reverse severe
bronchoconstriction during bronchoprovocation. Best practice: Confirm emergency
medications and protocols before initiating any challenge.
Question 5
During calibration of a blood gas analyzer, the technologist notes that the pH value for the
low calibrant is outside the acceptable range. What is the most appropriate initial action?
A. Report patient results using the current calibration
B. Repeat calibration with fresh calibrant solutions
C. Adjust the analyzer's internal pH slope manually
D. Perform a two-point calibration using only the high calibrant
Correct Answer: B
Explanation: Out-of-range calibration values often result from expired or contaminated
calibrants; fresh solutions should be tried first. Clinical pearl: Document all calibration
failures and corrective actions.
, Question 6
A technologist is preparing a DLCO system for testing. Which gas mixture is standard for the
single-breath technique?
A. 0.3% CO, 10% He, 21% O₂, balance N₂
B. 0.3% CO, 10% CH₄, 21% O₂, balance N₂
C. 1.0% CO, 5% He, 21% O₂, balance N₂
D. 0.1% CO, 15% Ne, 21% O₂, balance N₂
Correct Answer: A
Explanation: The standard DLCO test gas contains 0.3% CO and 10% helium as the tracer gas
with 21% oxygen. Clinical pearl: Helium allows calculation of alveolar volume from single-
breath dilution.
Question 7
What is the primary purpose of a biological control subject in a pulmonary function
laboratory?
A. To calibrate the spirometer daily
B. To verify that equipment and technique produce stable longitudinal results
C. To establish new predicted reference values
D. To train new technologists in testing procedures
Correct Answer: B
