Electrical interference on an ECG trace is commonly caused by what?

Electrical interference on an ECG trace is commonly caused by what?

• A. Sweat on skin
• B. Close proximity to an electrical device
• C. Motion artifact
• D. Battery issue

Answer: (B)

Electrical interference on an ECG trace comes from external electromagnetic fields that couple into the recording leads when a device is nearby. The close proximity lets these fields ride along the wires, often producing a regular hum at mains frequency (50/60 Hz) that distorts the tracing. This is the best explanation because it points to an external source directly affecting the signal rather than changes in the skin contact or the device’s power. Other issues have different patterns: sweat on the skin alters electrode impedance and causes baseline drift or transient noise; motion artifact shows up as irregular, jerky spikes from movement; a battery problem tends to cause the device to fail or the signal to drop out, not a continuous EMI pattern. Keeping the patient and the equipment separated or properly shielding and grounding the setup helps reduce this interference.

Electrical interference on an ECG trace comes from external electromagnetic fields that couple into the recording leads when a device is nearby. The close proximity lets these fields ride along the wires, often producing a regular hum at mains frequency (50/60 Hz) that distorts the tracing. This is the best explanation because it points to an external source directly affecting the signal rather than changes in the skin contact or the device’s power.

Other issues have different patterns: sweat on the skin alters electrode impedance and causes baseline drift or transient noise; motion artifact shows up as irregular, jerky spikes from movement; a battery problem tends to cause the device to fail or the signal to drop out, not a continuous EMI pattern. Keeping the patient and the equipment separated or properly shielding and grounding the setup helps reduce this interference.