RPFT Practice Questions
Prepare for RPFT with more than an answer.
- Exam fee
- $200 USD
- Level
- Specialist
- Valid for
- Lifetime credential (does not expire)
Domains covered on the exam 3
- Instrumentation/Equipment33%
- Procedures44%
- Data Management23%
- 1
Which three of the following are considered absolute contraindications for performing a methacholine challenge test? (Select THREE)
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Correct answer: A, B, D
- 2
True or False: When performing biological quality control on a spirometer, the results from the technician must fall within +/- 3% of their established mean FEV1 and FVC values.
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Correct answer: B
False. While +/- 3% is the accuracy standard for a 3-liter calibration syringe, the acceptable range for biological controls is wider due to inherent physiological variability. The acceptable range is typically established using standard deviations (e.g., within 2 SD of the mean) from a series of measurements performed by a healthy technician when the device was known to be functioning correctly. A common rule of thumb is within 5-10% of the mean, not 3%.
- 3
A patient performs an FVC maneuver, and the flow-volume loop shows a 'saw-tooth' pattern on both the inspiratory and expiratory limbs. This finding is most suggestive of:
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Correct answer: D
The 'saw-tooth' pattern, characterized by rapid oscillations in flow, is a classic sign of upper airway instability or flutter. It is frequently associated with conditions like obstructive sleep apnea (OSA), vocal cord dysfunction, or other forms of upper airway obstruction. While coughing can cause artifacts, the consistent pattern on both inspiration and expiration is highly suggestive of this underlying pathology.
- 4
A technologist is setting up a gas analyzer to measure CO concentration for a DLCO test. The calibration procedure requires a gas with a known concentration of 0.3% CO, 21% O2, and a balance of N2. Which type of gas analyzer is most commonly used for this purpose?
pie title="Gases in DLCO Test Mixture" "Carbon Monoxide": 0.3 "Tracer Gas (e.g., CH4)": 0.3 "Oxygen": 21 "Nitrogen (Balance)": 78.4Show answer details
Correct answer: B
Infrared gas analyzers are used to measure carbon monoxide (CO) because CO is a polyatomic molecule that absorbs infrared radiation at a specific wavelength. This property allows for a highly specific and accurate measurement of its concentration, which is critical for the DLCO calculation. Thermal conductivity is used for helium, electrochemical for oxygen, and emission spectroscopy for nitrogen.
- 5
A patient with kyphoscoliosis is unable to stand upright for a height measurement. Which of the following is the most appropriate alternative method for estimating height to select reference values?
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Correct answer: C
For patients who cannot stand straight due to conditions like kyphoscoliosis, or for wheelchair-bound patients, arm span is the recommended surrogate for height. In most adults, arm span is approximately equal to standing height. Using this measurement allows for the selection of more appropriate predicted values for pulmonary function tests.
- 6
A pulmonary function technologist is performing daily quality control on a body plethysmograph using an isothermal lung analog. The known volume of the analog is 3.00 L. The three measured volumes are 3.15 L, 3.16 L, and 3.14 L. Ambient temperature is 22°C and barometric pressure is 760 mmHg. Which of the following is the most likely cause for this consistent overestimation?
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Correct answer: B
A consistently inaccurate but precise measurement during biological QC often points to a systemic calibration or data entry error. In a plethysmograph, Boyle's law (P1V1=P2V2) is fundamental. An incorrectly entered, lower-than-actual barometric pressure would cause the system to calculate a larger volume to compensate, leading to the observed overestimation. A leak would typically cause more variability and drift, not a consistent offset. The panting frequency affects resistance, not volume QC. An uncalibrated mouth pressure transducer would also introduce variability or a different error pattern.
- 7
A patient with suspected neuromuscular weakness is coached to perform a maximal inspiratory pressure (MIP) maneuver. The patient performs three efforts, generating pressures of -45 cmH2O, -65 cmH2O, and -62 cmH2O. According to ATS/ERS guidelines, what should the technologist report?
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Correct answer: B
ATS/ERS guidelines for respiratory muscle strength testing state that the highest pressure sustained for at least one second from at least three acceptable maneuvers that vary by less than 20% should be reported. In this case, the highest value is -65 cmH2O. The first value (-45) is more than 20% different from the other two, suggesting a learning effect or suboptimal effort, but the two highest values (-65 and -62) are within 20% of each other, meeting repeatability criteria. The highest valid measurement is reported, not the average.
- 8
A patient's spirometry results are as follows: FVC = 2.5 L (55% pred), FEV1 = 1.0 L (35% pred), FEV1/FVC = 40%. After administration of a bronchodilator, the FEV1 increases to 1.25 L and FVC increases to 2.8 L. How should the technologist interpret the bronchodilator response?
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Correct answer: C
According to ATS/ERS criteria, a significant bronchodilator response is an increase of >12% AND >200 mL in either FEV1 or FVC from baseline.
FEV1 change: (1.25 L - 1.0 L) = 0.25 L (or 250 mL), which is >200 mL. The percent change is (0.25 L / 1.0 L) * 100 = 25%, which is >12%. So, the FEV1 response is significant.
FVC change: (2.8 L - 2.5 L) = 0.30 L (or 300 mL), which is >200 mL. The percent change is (0.30 L / 2.5 L) * 100 = 12%. So, the FVC change is also significant. Since both parameters show a significant change, the overall response is significant. - 9
A laboratory performs a linearity check on a new spirometer using a 3.0 L calibration syringe. Stepwise injections of 1.0 L are performed. The spirometer measures the volumes as 1.01 L, 2.03 L, and 3.05 L. Which ATS/ERS standard is being evaluated, and do these results meet the criteria?
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Correct answer: B
This procedure evaluates the linearity of the spirometer, which is its ability to provide accurate measurements across its volume range. The ATS/ERS standard for linearity requires that the measured volume at each step be within 3% of the reading or 50 mL, whichever is greater.
Step 1: 1.01 L is a 1% error from 1.0 L. (Meets criteria)
Step 2: 2.03 L is a 1.5% error from 2.0 L. (Meets criteria)
Step 3: 3.05 L is a 1.67% error from 3.0 L. (Meets criteria)
Since all points are well within the 3% tolerance, the spirometer meets the linearity standard. - 10
A 6-minute walk test (6MWT) is performed on a patient with idiopathic pulmonary fibrosis. The patient begins the test with an SpO2 of 95% on room air. After 3 minutes, their SpO2 drops to 87% and they report severe dyspnea. According to ATS guidelines, which TWO actions should the technologist take? (Select TWO)
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Correct answer: A, C
The ATS guidelines for the 6MWT provide specific criteria for stopping the test. Significant oxygen desaturation (typically to <88%) and patient-reported intolerable dyspnea are absolute indications to terminate the test for safety. The technologist must stop the test immediately and have the patient rest. It is also critical to document the reason for stopping, the time elapsed, the distance covered, and the lowest SpO2 reading.
