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Problem
High frequencies and muscle artifacts
make ECG signal noisy.
(This may occur concurrently with AC
noises)
Noisy ECG signal due to AC power
interferences
Possible Cause
● Patient has stress or placed in
an uncomfortable condition.
● Patient feels cold and starts
shaking.
● Improper placement of patient
hands and feet.
● Bed dimensions are not
suitable for comfortable
placement of patient hands and
feet.
● Limb electrodes are attached
tightly.
● Electrodes are placed on bony
site of the patient body.
● Unclean or sulfated electrodes
● Insufficient gel is applied.
● Contact with metal parts of
bed, trolley, etc.
● Lead wires, patient cable or
power cable fails to make
connection.
● There are other electronic
devices in the vicinity of the
electrocardiograph.
● Improper ambient light for
example using fluorescent lamp
in the room which ECG record is
taken.
● Incorrect HUM Filter is used.
● Improper Earth system
0
Solution
● Relax the patient.
● Check electrodes connection.
●If the problem persists, use
EMG or Lowpass filter.
● If the problem still persists, take the
following actions to reduce AC noise.
● Check electrodes and lead wires
connection.
● Check that lead wires are not
tangled.
● Check that the patient does not
contact the metal parts.
● Check that patient cable and power
cable have no contact.
● Check the selected HUM Filter.
● If the problem persists, unplug the
power cable (the device runs on the
battery). If the problem is solved, you
can make sure that noise source is the
device‟s power supply.
● If the problem still persists, noise
source may be other devices, room or
its earth system. Consequently this
room is not suitable for ECG
recording.
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