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Tr ou bleshoo t i n g ca r diac m o nit o r
p r o blems
For optimal cardiac monitoring, you need to recognize problems
that can interfere with getting a reliable ECG recording. Causes of
interference include artifact from patient movement and poorly
placed or poorly functioning equipment.
An artifact, also called waveform interference, may be seen with
excessive movement (somatic tremor). It makes the baseline of
the ECG appear wavy, bumpy, or tremulous. Dry electrodes may
also cause this problem because of poor contact.
Electrical interference, also called AC interference or 60-cycle
interference, is caused by electrical power leakage. It may also
result from interference from other room equipment or improperly
grounded equipment. As a result, the lost current pulses at a rate
of 60 cycles/second. This interference appears on the ECG as a
baseline that’s thick and unreadable.
For a look at the most commonly encountered monitor problems,
including the way to identify them, their possible causes, and interventions, see the next page.
Source: Interpreting Difficult ECGs: A Ready Reference, Lippincott Williams &
Wilkins, 2006.
Take5 © 2007 Lippincott Williams & Wilkins. Available online at http://
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Waveform
Possible
causes
Interventions
Waveform
Possible
causes
Interventions
Artifact (waveform
interference)
■ Patient experiences seizures,
chills, or anxiety
■ If the patient is having a seizure, provide emergency care
and notify the physician.
■ Keep the patient warm and
encourage him to relax.
Weak signal
■ Improper electrode application
■ Reapply the electrodes.
■ QRS complex
too small to register
■ Dirty or corroded
connections
■ Replace dirty or corroded
wires.
■ Reset gain so the height of the complex is greater than 1 mV.
■ Try monitoring the patient on another
lead.
■ Check the electrodes and
reapply them if needed. Clean
the patient’s skin well, because
skin oils and dead skin cells
inhibit conduction.
■ Wire or cable
failure
■ Replace any faulty wires or cables.
■ Improper electrode application
■ Patient restlessness
■ Encourage him to relax.
■ Dry electrode gel
■ Check the electrode gel. If it’s
dry, apply new electrodes.
■ Short circuit in
lead wires or cable
■ Replace broken equipment
■ Electrical interference from other
equipment in the
room
■ Make sure all electrical equipment is attached to a common
ground.
■ Check all three-pronged plugs
to make sure no prong is loose.
Notify biomedical department.
■ Static electricity
interference from
inadequate room
humidity
■ Regulate room humidity to
40% if possible.
False high-rate alarm ■ Gain setting too
high, particularly
with MCL1 setting
■ HIGH alarm set
too low or LOW
alarm set too high.
■ Assess the patient for signs
and symptoms of hyperkalemia.
Reset gain.
■ Set alarm limits according to
the patient’s heart rate.
Wandering baseline
■ Exaggerated
■ Make sure that tension on the cable
chest wall move- isn’t pulling the electrode away from
ment during
the patient’s body.
respiration
■ Improper elec- ■ Reposition improperly placed electrode application; trodes.
electrode positioned over bone
Fuzzy baseline
(electrical interference)
■ Electrical interference from
other equipment
in the room
■ Make sure that all electrical equipment being used, such as an I.V.
pump, is attached to a common
ground.
■ Check all three-pronged plugs to
make sure no prong is loose. Notify
biomedical department.
Baseline (no waveform)
■ Improper electrode placement
■ Reposition improperly placed electrodes.
■ Electrode disconnection
■ Check for disconnected electrodes.
■ Dry electrode
gel
■ Check electrode gel. If it’s dry, apply
new electrodes.
■ Wire or cable
failure
■ Replace any faulty wires or cables.