CBET Preventive Maintenance and Calibration 4 — Questions and Answers
Question 1: When calibrating a pulse oximeter, which reference standard is most appropriate for verifying SpO2 accuracy?
- A multiwavelength CO-oximeter measuring arterial blood samples (Correct answer)
- A benchtop optical simulator set to 98%
- A finger phantom with fixed LED output
- A capnograph reading end-tidal CO2
Correct answer: A multiwavelength CO-oximeter measuring arterial blood samples
CO-oximetry on arterial blood samples is the gold standard for verifying pulse oximeter SpO2 accuracy because it directly measures hemoglobin saturation.
Question 2: A biomedical technician notices that an infusion pump's flow rate drifts 8% above the set value after 30 minutes of operation. The most likely PM corrective action is:
- Replace the pump motor assembly
- Recalibrate the peristaltic mechanism and inspect tubing wear (Correct answer)
- Increase the occlusion alarm threshold
- Replace the control PCB
Correct answer: Recalibrate the peristaltic mechanism and inspect tubing wear
Flow rate drift in peristaltic pumps is commonly caused by worn tubing or a misaligned rotor, both addressed during PM through recalibration and tubing inspection.
Question 3: Which document should a BMET consult first to determine PM intervals for a newly acquired ventilator?
- The hospital's infection control policy
- The manufacturer's service manual and recommended maintenance schedule (Correct answer)
- OSHA 29 CFR 1910 general industry standards
- The previous facility's PM records
Correct answer: The manufacturer's service manual and recommended maintenance schedule
Manufacturer service manuals contain device-specific PM intervals based on engineering design life and regulatory submissions, making them the primary reference.
Question 4: During PM on an electrocoagulation unit, the output power is measured 15% below the displayed setting. Which step should the technician perform next?
- Tag the device out of service immediately
- Adjust the internal power calibration potentiometer per service manual (Correct answer)
- Replace the RF output transformer
- Increase the generator voltage supply rail
Correct answer: Adjust the internal power calibration potentiometer per service manual
A 15% power output deviation is within the range correctable by internal calibration adjustment before component replacement is warranted.
Question 5: A PM checklist for a defibrillator requires verifying delivered energy at 200 J. The analyzer reads 188 J. Per AAMI standards, this result is:
- Acceptable; within the ±15% tolerance allowed (Correct answer)
- Unacceptable; defibrillators must deliver within ±5 J
- Acceptable; any reading above 150 J passes
- Unacceptable; only ±1% tolerance is permitted
Correct answer: Acceptable; within the ±15% tolerance allowed
AAMI DF80 allows defibrillator delivered energy to be within ±15% of the selected setting; 188 J is a 6% deviation and therefore acceptable.
Question 6: What is the primary purpose of recording 'as-found' data before making any PM adjustments?
- To satisfy OSHA record-keeping requirements
- To document the device's condition prior to servicing for trending and audit purposes (Correct answer)
- To establish a billing baseline for parts replacement
- To notify the manufacturer of out-of-tolerance findings
Correct answer: To document the device's condition prior to servicing for trending and audit purposes
As-found data captures the device's pre-PM state, enabling performance trending, failure pattern analysis, and regulatory audit trails.
Question 7: A technician is performing PM on a patient-controlled analgesia (PCA) pump and must verify occlusion alarm response. The correct test method is:
- Block the outlet tubing and measure elapsed time to alarm activation (Correct answer)
- Disconnect the AC power and measure battery backup alarm delay
- Increase the infusion rate beyond maximum and observe the display
- Introduce air into the IV line and monitor the air-in-line sensor
Correct answer: Block the outlet tubing and measure elapsed time to alarm activation
Occlusion alarm testing requires physically blocking fluid flow at the outlet and confirming the pump alarms within the manufacturer's specified time limit.
CBET Preventive Maintenance and Calibration 4
When calibrating a pulse oximeter, which reference standard is most appropriate for verifying SpO2 accuracy?