CBET Healthcare Technology Problem-Solving 4 — Questions and Answers
Question 1: A ventilator's tidal volume display reads 500 mL but a calibrated test lung measurement shows only 420 mL. What is the most likely cause?
- Flow sensor calibration drift (Correct answer)
- Incorrect PEEP setting
- Low oxygen supply pressure
- Faulty inspiratory valve
Correct answer: Flow sensor calibration drift
Flow sensor drift is the most common cause of tidal volume display inaccuracy when the set and delivered volumes differ consistently.
Question 2: A nurse reports that a patient's SpO2 monitor reads 98% while the patient appears cyanotic. Which troubleshooting step should be performed first?
- Check probe placement and peripheral perfusion (Correct answer)
- Replace the entire monitor
- Recalibrate the SpO2 module
- Measure ABG immediately and discard the monitor reading
Correct answer: Check probe placement and peripheral perfusion
Poor perfusion or improper probe placement are the most common causes of falsely high SpO2 readings before escalating to hardware replacement.
Question 3: An infusion pump alarms 'upstream occlusion' but the tubing appears clear. What should the BMET check next?
- Closed roller clamp or kinked tubing upstream of the pump (Correct answer)
- Battery level of the pump
- Software version of the pump firmware
- IV bag height relative to the patient
Correct answer: Closed roller clamp or kinked tubing upstream of the pump
A closed clamp or subtle kink upstream of the pump head is the most frequent cause of upstream occlusion alarms when visible tubing appears unobstructed.
Question 4: During a preventive maintenance inspection, an electrosurgical unit's leakage current measures 450 µA chassis to ground. What action is required?
- Remove from service; leakage exceeds the 300 µA limit for ESUs (Correct answer)
- Return to service; the reading is within acceptable limits
- Install an additional ground wire and retest
- Report to nursing and continue normal use
Correct answer: Remove from service; leakage exceeds the 300 µA limit for ESUs
NFPA 99 and AAMI ES60601-1 limit chassis leakage current to 300 µA for patient-care equipment; 450 µA requires the unit be taken out of service.
Question 5: A defibrillator delivers only 150 J when set to 200 J during an output verification test. After replacing the energy storage capacitor the problem persists. What should be investigated next?
- Charging circuit and charge relay (Correct answer)
- Patient cable integrity
- Battery voltage under load
- Front-panel display calibration
Correct answer: Charging circuit and charge relay
If the capacitor is confirmed good, the charging circuit or charge relay is the next most likely cause of low delivered energy.
Question 6: A hospital bed's weight scale consistently reads 5 kg below the known weight of a calibration mass. Which corrective action is most appropriate?
- Perform a span calibration adjustment using NIST-traceable weights (Correct answer)
- Replace the load cell immediately
- Zero the scale with the patient in bed
- Add a correction factor to nursing documentation
Correct answer: Perform a span calibration adjustment using NIST-traceable weights
A consistent offset (span error) is corrected through span calibration using traceable reference weights, not by replacing hardware first.
Question 7: A patient monitor's ECG trace shows excessive 60 Hz artifact despite proper lead placement. After checking lead connections, what is the next troubleshooting step?
- Verify patient ground electrode contact and integrity (Correct answer)
- Replace the ECG module
- Switch the monitor to a different electrical outlet
- Increase the filter bandwidth setting
Correct answer: Verify patient ground electrode contact and integrity
Poor or absent ground (RL/right-leg drive) electrode contact is the most common cause of persistent 60 Hz powerline interference on ECG.
CBET Healthcare Technology Problem-Solving 4
A ventilator's tidal volume display reads 500 mL but a calibrated test lung measurement shows only 420 mL.
What is the most likely cause?