MONITORING IN ICU : Ecg monitoring

 MONITORING IN ICU

Goals of ECG monitoring

Following are the usual goals of ECG monitoring in the intensive coronary care unit:

● Heart rate and basic rhythm determination

● Diagnosis of complex arrhythmias

● Detection of ischemia and prolonged QT interval

Advanced monitoring facilities may be used for the following features which are yet to be well established:

● Computerized ST segment analysis

● Computerized arrhythmia analysis

● Computerized QT-interval monitoring

Improvements in ECG monitoring

Over the past few decades since the initiation of ECG monitoring in the 1960s, several improvements have occured. They include improved noise reduction strategies, multilead monitoring and derived 12-lead ECGs.

Cardiac arrhythmia monitoring

Cardiac arrhythmia monitoring is needed for all patients at significant risk of an immediate, life-threatening arrhythmia, which include: Post cardiac arrest, early phase of acute coronary syndrome, post cardiac surgery and after anesthesia. Battery-operated monitor-defibrillators are useful while transporting such patients. Personnel watching the monitor in the ICU should have skill in ECG interpretation and defibrillation.

ST-segment ischemia monitoring

In the setting of an acute myocardial infarction ST segment ischemia monitoring is useful to assess the patency of culprit artery after thrombolysis, abrupt reocclusion after primary angioplasty and to detect ongoing ischemia / infarct extension. ST segment monitoring is not useful in left bundle branch block, ventricular paced rhythm, arrhythmias that obscure the ST Segment and in patients who are agitated.

Which lead to monitor?

Have a look at the 12 lead ECG before deciding on which lead to monitor. Usually lead II is monitored in most patients as it gives good P waves for rhythm interpretation. But in several patients, limb lead voltages may be low so that heart rate counting becomes erroneous. Good R wave amplitude is needed for counting the heart rate accurately so that false alarms can be avoided. If T wave is very tall in the monitoring lead, it leads to T wave oversensing and dual counting sometimes. When limb leads do not give P and QRS complexes, chest lead monitoring may be needed in some cases. Usually ICU staff prefer not to use chest lead monitoring as it interferes with auscultation, echocardiography and even defibrillation in case of an emergency.