CABT Equipment Maintenance and Troubleshooting 4 — Questions and Answers
Question 1: A syringe pump's occlusion alarm activates repeatedly even though the IV line appears patent. The technician should first:
- Replace the syringe with a larger volume
- Inspect the occlusion pressure sensor and calibrate it per service manual (Correct answer)
- Override the alarm threshold to maximum
- Administer the medication via gravity drip instead
Correct answer: Inspect the occlusion pressure sensor and calibrate it per service manual
Repeated false occlusion alarms suggest a misaligned or out-of-calibration pressure sensor; inspection and calibration are the correct first steps.
Question 2: During PM on a patient scale, you find it reads 2 kg high across all weight ranges. This indicates the need for:
- Zero offset adjustment only
- Span (gain) calibration adjustment (Correct answer)
- Load cell replacement
- Software update
Correct answer: Span (gain) calibration adjustment
A consistent error that is proportional across the range indicates a span or gain error, requiring span calibration to correct the slope of the response.
Question 3: A portable X-ray unit fails to expose after pressing the trigger. The kVp and mAs settings are correct. Which component should the biomedical technician inspect first?
- The tube cooling system
- The dead-man switch and exposure trigger circuit (Correct answer)
- The collimator shutters
- The automatic exposure control (AEC) sensor
Correct answer: The dead-man switch and exposure trigger circuit
If the unit does not expose at all, the trigger/dead-man switch circuit is the most likely point of failure and should be inspected first.
Question 4: Which of the following is the correct action when a medical device is found with a frayed power cord during a PM inspection?
- Tag the cord with a warning and return the device to service
- Tape the frayed area and document in the work order
- Remove the device from service and replace the cord before returning it (Correct answer)
- Increase the PM frequency for that device
Correct answer: Remove the device from service and replace the cord before returning it
A frayed power cord is an immediate electrical safety hazard; the device must be taken out of service and the cord replaced before it can be returned to clinical use.
Question 5: The term 'mean time between failures' (MTBF) is used in biomedical equipment management to:
- Calculate the cost per repair
- Estimate how often a device is expected to fail under normal operation (Correct answer)
- Determine the maximum leakage current allowed
- Set the minimum PM interval required by regulation
Correct answer: Estimate how often a device is expected to fail under normal operation
MTBF is a reliability metric that estimates the average operating time between failures for a device under normal use conditions.
Question 6: A bladder scanner produces inconsistent volume readings between measurements on the same patient. The most common cause is:
- Incorrect ultrasound frequency selected
- Variation in transducer angle and positioning by the user (Correct answer)
- Degraded battery voltage
- Software version incompatibility
Correct answer: Variation in transducer angle and positioning by the user
Bladder scanner accuracy is highly dependent on correct transducer placement and angle; user technique variation is the most common cause of inconsistent readings.
Question 7: Which document must be completed and retained after every corrective maintenance (repair) event on a regulated medical device?
- Device history record (DHR) (Correct answer)
- Institutional review board (IRB) approval
- 510(k) clearance form
- Material safety data sheet (MSDS/SDS)
Correct answer: Device history record (DHR)
FDA regulations and hospital accreditation standards require that a device history record (or equivalent work order) be completed and retained for every corrective maintenance event.
CABT Equipment Maintenance and Troubleshooting 4
A syringe pump's occlusion alarm activates repeatedly even though the IV line appears patent.
The technician should first: