CBET Preventive Maintenance and Calibration 5 — Questions and Answers
Question 1: When using a electrical safety analyzer to perform a leakage current test on a Class I medical device, what is the maximum allowable chassis leakage current under normal conditions per NFPA 99?
- 100 µA (Correct answer)
- 300 µA
- 500 µA
- 10 µA
Correct answer: 100 µA
NFPA 99 and AAMI ES60601-1 limit chassis (enclosure) leakage current for Class I devices to 100 µA under normal conditions.
Question 2: A biomedical technician is calibrating a non-invasive blood pressure (NIBP) module. Which instrument is required to verify cuff pressure accuracy?
- A certified digital manometer or pressure calibrator (Correct answer)
- A mercury sphygmomanometer
- A patient simulator set to a known BP value
- An oscillometric waveform analyzer
Correct answer: A certified digital manometer or pressure calibrator
A calibrated digital manometer or pressure calibrator directly measures the pneumatic pressure applied to the cuff, providing a traceable reference for NIBP calibration.
Question 3: Which PM task is unique to laser surgical equipment compared to conventional electrosurgical units?
- Verifying beam alignment, output power, and protective eyewear integrity (Correct answer)
- Measuring RF leakage current at the patient return electrode
- Checking the dispersive electrode impedance monitor
- Testing arc suppression capacitors
Correct answer: Verifying beam alignment, output power, and protective eyewear integrity
Laser PM includes optical alignment verification, measured output power against rated specifications, and inspection of safety interlocks and wavelength-appropriate eyewear.
Question 4: During PM on a physiological monitor, the technician observes that the ECG trace has a 60 Hz artifact that persists after replacing lead wires. The next troubleshooting step is:
- Verify the device chassis ground continuity and check the common mode rejection ratio (CMRR) (Correct answer)
- Replace the display screen
- Increase the ECG gain setting
- Switch the monitor to bipolar lead configuration only
Correct answer: Verify the device chassis ground continuity and check the common mode rejection ratio (CMRR)
Persistent 60 Hz artifact after lead replacement typically indicates a grounding deficiency or degraded CMRR in the amplifier, both assessed during PM.
Question 5: A PM procedure requires lubricating the drive mechanism of an OR table. Which lubricant is contraindicated in this environment?
- Petroleum-based grease where O-rings or oxygen lines are nearby (Correct answer)
- Food-grade silicone grease
- Manufacturer-specified synthetic grease
- Dry PTFE lubricant spray
Correct answer: Petroleum-based grease where O-rings or oxygen lines are nearby
Petroleum-based lubricants can degrade rubber O-rings and create fire or explosion hazards in oxygen-enriched surgical environments.
Question 6: A hospital's PM program is evaluated during a Joint Commission survey. The surveyor asks for evidence that PM completion rates meet the required threshold. What is that threshold?
- 100% for life-support equipment; ≥90% overall (Correct answer)
- ≥80% for all equipment categories
- ≥95% for all equipment categories
- 100% for all medical devices without exception
Correct answer: 100% for life-support equipment; ≥90% overall
The Joint Commission requires 100% PM completion for life-support devices and generally accepts ≥90% completion for non-life-support equipment in the overall program.
Question 7: Which concept describes the practice of adjusting PM frequency based on a device's historical failure rate and clinical risk level?
- Reliability-centered maintenance (RCM) (Correct answer)
- Corrective maintenance scheduling
- Predictive failure indexing
- Total productive maintenance (TPM)
Correct answer: Reliability-centered maintenance (RCM)
Reliability-centered maintenance uses failure history and risk analysis to optimize PM intervals, reducing unnecessary maintenance while protecting patient safety.
CBET Preventive Maintenance and Calibration 5
When using a electrical safety analyzer to perform a leakage current test on a Class I medical device, what is the maximum allowable chassis leakage current under normal conditions per NFPA 99?