CET CET Equipment Operation and Maintenance 1 — Questions and Answers
Question 1: What does the standard paper speed setting of 25 mm/sec mean on an EKG tracing?
- Each large box represents 0.04 seconds
- Each small box represents 0.04 seconds horizontally (Correct answer)
- Each large box represents 0.5 mV
- Each small box represents 0.5 mV
Correct answer: Each small box represents 0.04 seconds horizontally
At 25 mm/sec, each 1 mm small box on the horizontal axis equals 0.04 seconds of time.
Question 2: What is the standard voltage calibration for a clinical EKG machine?
- 5 mm/mV
- 10 mm/mV (Correct answer)
- 25 mm/mV
- 1 mm/mV
Correct answer: 10 mm/mV
Standard EKG calibration is 10 mm/mV, meaning a 1 mV signal produces a 10 mm deflection on the paper.
Question 3: A calibration pulse at the start of an EKG tracing appears shorter than expected (5 mm instead of 10 mm). This indicates the machine is set to:
- Full standard (10 mm/mV)
- Half standard (5 mm/mV) (Correct answer)
- Double standard (20 mm/mV)
- 25 mm/sec paper speed
Correct answer: Half standard (5 mm/mV)
A 5 mm calibration pulse indicates the machine is set to half standard, which is used when large-amplitude waveforms extend off the paper.
Question 4: What is the primary purpose of the filter settings (e.g., 40 Hz, 150 Hz) on a modern EKG machine?
- To increase paper speed
- To reduce electrical artifact and noise without distorting cardiac waveforms (Correct answer)
- To calibrate electrode impedance
- To select the number of leads to record
Correct answer: To reduce electrical artifact and noise without distorting cardiac waveforms
Filters attenuate high-frequency or low-frequency noise (such as muscle artifact or AC interference) while preserving the diagnostic waveform shape.
Question 5: Which lead wire color corresponds to the right arm (RA) electrode in the American (AHA) color-coding system?
- Black
- Green
- White (Correct answer)
- Red
Correct answer: White
In the AHA system used in the US, white identifies the right arm lead wire.
Question 6: How often should reusable EKG lead wires and clips be cleaned according to standard infection control practices?
- Once per week during scheduled maintenance
- After each patient use (Correct answer)
- Only when visibly soiled
- Once per month
Correct answer: After each patient use
Reusable lead wires must be disinfected after each patient to prevent cross-contamination between patients.
CET CET Equipment Operation and Maintenance 1
What does the standard paper speed setting of 25 mm/sec mean on an EKG tracing?