RPFT RPFT Equipment Calibration & Quality Control 2 — Questions and Answers
Question 1: What environmental data must be entered into a spirometry system before testing to allow BTPS correction?
- Ambient temperature, barometric pressure, and relative humidity (Correct answer)
- Patient age, height, and weight only
- Room CO2 concentration and ventilation rate
- Time of day and altitude above sea level
Correct answer: Ambient temperature, barometric pressure, and relative humidity
BTPS (Body Temperature, Pressure, Saturated) correction requires ambient temperature, barometric pressure, and humidity to convert measured gas volumes to body conditions.
Question 2: A peak flow meter shows readings 15% below the lab spirometer for the same patient. What is the most appropriate first action?
- Recalibrate or replace the peak flow meter (Correct answer)
- Retest the patient on the spirometer
- Document the discrepancy and proceed
- Attribute the difference to patient effort
Correct answer: Recalibrate or replace the peak flow meter
A consistent 15% discrepancy suggests instrument error; the peak flow meter should be checked against a reference or replaced before relying on its readings.
Question 3: Which gas mixture is used to calibrate the DLCO analyzer?
- A precision gas with known concentrations of CO and an inert tracer gas (Correct answer)
- Room air with 21% oxygen
- 100% carbon monoxide for span calibration
- Pure helium for zero calibration
Correct answer: A precision gas with known concentrations of CO and an inert tracer gas
DLCO analyzers require a certified precision calibration gas containing specific concentrations of CO and an inert tracer (e.g., methane or helium) for accurate two-point calibration.
Question 4: What is the primary purpose of the mechanical pump ('super syringe') used in DLCO system calibration?
- To verify the accuracy of inspired volume measurement at known flow rates (Correct answer)
- To flush residual CO from the analyzer
- To generate a known diffusion capacity signal
- To test the one-way valve integrity of the system
Correct answer: To verify the accuracy of inspired volume measurement at known flow rates
The super syringe delivers known volumes at controlled flow rates to verify that the spirometric component of the DLCO system measures inspired volume accurately.
Question 5: After replacing a flow sensor, what is the minimum verification a RPFT should perform before resuming patient testing?
- Full calibration including volume accuracy and linearity checks (Correct answer)
- A single 3-liter syringe stroke
- A biological control test only
- Visual inspection of the sensor connections
Correct answer: Full calibration including volume accuracy and linearity checks
Any hardware change requires a complete recalibration to ensure the new sensor performs within acceptable accuracy limits across its entire range.
Question 6: What is the recommended ambient temperature range for performing pulmonary function tests?
- 17–40°C (63–104°F) (Correct answer)
- 0–100°C
- 36–38°C only
- Below 20°C to minimize patient discomfort
Correct answer: 17–40°C (63–104°F)
ATS/ERS guidelines specify that spirometry should be performed when ambient temperature is between 17°C and 40°C to ensure reliable BTPS correction and sensor function.
RPFT RPFT Equipment Calibration & Quality Control 2
What environmental data must be entered into a spirometry system before testing to allow BTPS correction?