There are many factors that may affect the quality of the ECG trace appearing on the cardiac monitor so knowing how to minimise or prevent such problems is vital (Jevon 2003). Good practice involves always assessing the patient first before the equipment.
• Assess for evidence of cable damage.
• Check that all equipment is connected correctly.
• Ensure the gain has been set appropriately.
• Make sure lead II has been selected.
• Check electrodes are in date and intact.
Quality of the ECG trace is inadequate
• Review connections and cable.
• Assess that electrodes have been correctly placed.
• Check that the electrodes have not become displaced.
• Electrodes are in date and intact.
• Replace electrodes.
Wandering baseline and artefacts
• Voluntary artefact - can be caused by patient movement such as respiration. Consider moving electrodes.
• Involuntary artefact - includes interference caused by shivering or nervousness. Keep patient warm and provide emotional support.
• Electrical interference - this is due to electrical equipment such as infusion pumps and syringe drivers. Ensure minimal contact with cardiac leads.
• Loose electrode - a wandering baseline pattern suggests signal interruption due to a loose electrode, poor contact or incorrectly placed electrode.
• Complexes are too small - these may be due to clinical factors such as a cardiac tamponade or pericardial effusion. Select a different lead, increase amplitude or substitute electrodes.
• False heart rate on display - occasionally the ECG complexes appear as very small on the cardiac monitor, giving the impression of a reduced heart rate. At other times the T wave may be counted for an R wave, thus doubling the heart rate. Reposition electrodes or select another lead to correct this problem (Jevon 2003).
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