CET ECG Equipment Operation & Maintenance 2 — Questions and Answers
Question 1: Which ECG machine setting controls the speed at which paper moves during recording?
- Gain control
- Paper speed control (Correct answer)
- Filter selector
- Lead selector
Correct answer: Paper speed control
Paper speed control determines how fast the paper advances, with 25 mm/sec being the standard US setting.
Question 2: What is the purpose of the right leg (RL) electrode in a standard 12-lead ECG?
- Records inferior wall activity
- Serves as the electrical ground to reduce interference (Correct answer)
- Measures right ventricular voltage
- Acts as a reference for chest leads
Correct answer: Serves as the electrical ground to reduce interference
The right leg electrode serves as the electrical ground (neutral) to minimize common-mode noise and interference in the recording.
Question 3: When cleaning reusable ECG electrodes, which agent should be avoided because it can degrade the metal contact surface?
- Isopropyl alcohol
- Sodium hypochlorite (bleach) (Correct answer)
- Warm soapy water
- Hydrogen peroxide
Correct answer: Sodium hypochlorite (bleach)
Sodium hypochlorite (bleach) can corrode and pit metal electrode surfaces, degrading conductivity over time.
Question 4: A technician notices the ECG machine displays 'LEAD FAIL' for lead II. Which electrode connection should be checked first?
- Right arm (RA) and left arm (LA) electrodes
- Left arm (LA) and left leg (LL) electrodes
- Right arm (RA) and left leg (LL) electrodes (Correct answer)
- Right leg (RL) and left leg (LL) electrodes
Correct answer: Right arm (RA) and left leg (LL) electrodes
Lead II is derived from the potential difference between the right arm (RA, negative) and left leg (LL, positive), so those connections should be checked.
Question 5: What does the '1 mV standardization mark' at the beginning of an ECG tracing verify?
- That the paper speed is correct
- That electrode impedance is within range
- That the machine's sensitivity is properly calibrated at 10 mm/mV (Correct answer)
- That the low-pass filter is active
Correct answer: That the machine's sensitivity is properly calibrated at 10 mm/mV
The 1 mV standard pulse should produce a 10 mm (two large squares) deflection, confirming the machine is calibrated at standard sensitivity.
Question 6: Which precordial electrode placement is located at the fourth intercostal space, right sternal border?
- V1 (Correct answer)
- V2
- V3
- V4
Correct answer: V1
V1 is placed at the fourth intercostal space along the right sternal border, one of the two anchor points for precordial lead placement.
Question 7: When an ECG machine's internal battery is used during a power outage, which maintenance practice is most important?
- Replacing the battery monthly regardless of use
- Recharging the battery fully after each use and testing it regularly (Correct answer)
- Keeping the machine unplugged to preserve battery life
- Calibrating the gain setting after each battery use
Correct answer: Recharging the battery fully after each use and testing it regularly
Fully recharging after each use and performing periodic battery capacity tests ensures the backup power is reliable when needed.
CET ECG Equipment Operation & Maintenance 2
Which ECG machine setting controls the speed at which paper moves during recording?