CBET Ultimate 5 — Questions and Answers
Question 1: What is the primary difference between a Class I and Class II medical device under FDA classification?
- Class I devices are implantable; Class II are external only
- Class I requires general controls only; Class II requires special controls such as performance standards (Correct answer)
- Class I is for diagnostic devices; Class II is for therapeutic devices
- Class I requires PMA; Class II requires 510(k) clearance only
Correct answer: Class I requires general controls only; Class II requires special controls such as performance standards
FDA Class I devices are subject to general controls only, while Class II devices require special controls (e.g., performance standards, post-market surveillance) to ensure safety and effectiveness.
Question 2: A physiological pressure transducer requires zeroing before use. Why is this step necessary?
- To calibrate the gain of the amplifier
- To establish atmospheric pressure as the reference baseline, eliminating hydrostatic and offset errors (Correct answer)
- To test the transducer's frequency response
- To prime the fluid-filled tubing
Correct answer: To establish atmospheric pressure as the reference baseline, eliminating hydrostatic and offset errors
Zeroing the transducer at the level of the right atrium sets atmospheric pressure as the zero reference, ensuring accurate hemodynamic readings.
Question 3: Which parameter does a capnograph measure, and what waveform phase indicates end-tidal CO2?
- SpO2; the dicrotic notch
- CO2 concentration in exhaled breath; the alveolar plateau (Phase III) (Correct answer)
- Airway pressure; peak inspiratory pressure
- Respiratory rate; the expiratory downslope
Correct answer: CO2 concentration in exhaled breath; the alveolar plateau (Phase III)
Capnography measures exhaled CO2, and the end-tidal CO2 (EtCO2) value is read at the alveolar plateau (Phase III) of the capnogram waveform.
Question 4: During a PM on a hospital bed, you discover the brake does not engage fully. What is the correct action?
- Tag the bed out-of-service and remove from patient use pending repair (Correct answer)
- Notify nursing and continue using the bed with caution
- Apply lubricant to the brake mechanism and recheck
- Document the finding and schedule repair for next month
Correct answer: Tag the bed out-of-service and remove from patient use pending repair
A bed with a failed brake poses a fall and injury risk; it must be immediately tagged out-of-service and removed from clinical use until repaired and verified.
Question 5: What is the purpose of a Faraday cage in an MRI suite?
- To cool the superconducting magnet
- To shield external RF signals that would corrupt MRI image quality (Correct answer)
- To contain cryogenic helium gas
- To protect staff from gradient field exposure
Correct answer: To shield external RF signals that would corrupt MRI image quality
The RF-shielded Faraday cage prevents external radiofrequency interference from entering the MRI room and corrupting the weak MR signal during image acquisition.
Question 6: A hospital is evaluating a new ultrasound machine. Under FDA guidance, which testing verifies the acoustic output does not exceed safe limits?
- IEC 60601-1 electrical safety testing
- AIUM/NEMA measurement standards for acoustic output (MI and TI indices) (Correct answer)
- NFPA 99 medical gas testing
- ANSI Z136 laser safety standards
Correct answer: AIUM/NEMA measurement standards for acoustic output (MI and TI indices)
Mechanical Index (MI) and Thermal Index (TI) are standardized acoustic output metrics per AIUM/NEMA guidelines that the FDA uses to regulate safe ultrasound exposure levels.
Question 7: A nurse reports that an automated external defibrillator (AED) failed to advise a shock during a cardiac arrest drill. After replacing the dummy pad, it still shows 'check electrodes.' What should the BMET do next?
- Replace the battery immediately
- Test the AED's electrode impedance sensing circuit using a calibrated AED analyzer (Correct answer)
- Return the AED to service; drills are not representative
- Update the AED firmware
Correct answer: Test the AED's electrode impedance sensing circuit using a calibrated AED analyzer
A calibrated AED analyzer can simulate patient electrode impedance to verify whether the AED's electrode sensing and analysis circuits are functioning correctly.
CBET Ultimate 5
What is the primary difference between a Class I and Class II medical device under FDA classification?