Patients with diminished cardiac reserve who have undergone surgery should be monitored in the postoperative period. Myocardial infarction is most likely to occur in the first 6 days after non-cardiac surgery. Patients who have had coronary artery bypass grafting are at risk of ventricular and supraventricular arrhythmias and should have ECG monitoring. If atrial epicardial pacing electrodes are placed in the postbypass patient, another monitor can be used to display the atrial electrogram for early detection and diagnosis of atrial fibrillation and flutter.
Patients with severe neurological problems are susceptible to cardiac rhythm disorders and should have ECG monitoring. ECG monitoring is useful in patients with respiratory distress, including those requiring mechanical ventilation. Patients with acute drug toxicity from agents known to have arrhythmic consequences should be monitored. For example, an overdose of tricyclic antidepressants can result in torsade de pointes. In addition, we admit to telemetry units patients initiating therapy with potentially proarrhythmic drugs. Examples of such drugs are class I antiarrhythmics (such as quinidine) and class III antiarrhythmics (such as sotalol), which can induce torsade de pointes and other serious arrhythmias. Severe electrolyte abnormalities can cause arrhythmias which have hemodynamic consequences. Hyperkalemia, whether from altered renal function, drug effects, or severe tissue damage (as in burns), can result in severe bradyarrhythmias or ventricular fibrillation. Hypokalemia and hypomagnesemia can result in torsade de pointes. In each of these cases, cardiac monitoring can lead to early diagnosis and effective treatment. A summary of the American College of Cardiology recommendations for ECG monitoring (Jaffe elal 19,9.1) is shown in Table I
Table 1 American College of Cardiology guidelines for in-hospital cardiac monitoring of adults for detection of arrhythmia
When appropriately used, telemetry monitoring units without intensive care nursing are safe. Estrada .ef a/ (19,94) studied 467 telemetry unit admissions and found that the in-hospital mortality was 1.9 per cent; 8.1 per cent of patients required transfer to an ICU. Their study confirmed that telemetry patients are at lower arrhythmic risk than ICU patients. Only 1 per cent of the total population was transferred to an ICU because of ECG findings; the remainder were transferred because of other symptoms. This study reveals the current trend towards utilizing telemeters for management of lower-risk arrhythmias, diagnostic monitoring, and observation of patients at low risk of life-threatening arrhythmias.
It should be recognized that changes in cardiac rhythm are not sensitive early warning indicators of respiratory or hemodynamic distress. Patients at high risk of hemodynamic or respiratory problems should be admitted to ICUs, where the nurse-to-patient ratio is higher than on cardiac telemetry units.
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