Admit the patient for cardiac monitoring. A simple statement, but with the technology available today, you have choices to make to provide this service effectively for your patient. With the development of technologically advanced systems, hospitals have gone far beyond simply monitoring for dysrhythmias. Systems today offer computerized dysrhythmia analysis and can check multiple leads at once, derive full 12-lead electrocardiograms (ECGs) from the standard 5-lead set-up, trend data, and monitor for ST-segment changes.
The American Heart Association has published detailed standards in response to this increased capability to monitor for complex dysrhythmias, ST-segment changes, and QT-interval changes.1 The American College of Cardiology has developed guidelines defining which patients will benefit from cardiac monitoring.2 These organizations provide clear recommendations for best practices.
Review the criteria
Your hospital should have admission/discharge criteria set up for units that provide cardiac monitoring. A policy that defines the criteria is essential when multiple units provide cardiac monitoring.
Levels of monitoring intensity can be defined based on best-practice recommendations. Cardiac monitoring criteria provides guidelines for cardiac monitoring based on the admission diagnosis. If the patient doesn't have a dysrhythmia, you can discontinue monitoring (let the patient's health care provider know of this decision). If the health care provider overrides the decision, document this in the patient's medical record to justify ongoing cardiac monitoring. Establishing well-defined criteria, including discontinuation of cardiac monitoring in patients who'll no longer benefit from it, helps prevent the backlog that so often occurs in emergency departments as patients wait for beds in telemetry units and progressive care units.
Monitoring: Best practice
The American Association of Critical-Care Nurses (AACN) has published two practice alerts to define the best practices for monitoring patients for dysrhythmias and ST-segment changes.3,4 Simply placing a monitor on the patient, using a standard lead, and waiting for an alarm isn't enough. When a patient is admitted for cardiac monitoring, ask yourself these questions: Should I be concerned about QT prolongation? Is there a potential for ischemia? Should I monitor ST segments? Which leads should I use for ST-segment monitoring?
To prepare the patient for cardiac monitoring, adhere to the following steps (or those mandated by your facility):
1. Verify the order for telemetry monitoring.
2. Provide preprocedure education with verification of patient and family understanding.
3. Assess the patient.
4. Assess the patient's history for cardiac dysrhythmias or other cardiac problems. Is he being monitored for ischemia or dysrhythmias, or both? Choose the appropriate lead.
5. Properly prepare the patient's skin before applying the electrodes. Preparation may include clipping hair from areas where electrodes will be placed, performing mild abrasion of the skin with a washcloth, using a scratch pad on the electrode pad or gauze pad, and cleaning the skin with alcohol to remove skin oils.
6. Properly position leads on the patient. Accurate lead placement is critical. Consistent lead placement is also important because ECG information obtained from electrodes located close to the heart (precordial leads) is especially prone to waveform changes when the electrodes are removed and replaced as much as 1 cm from their original position. Mark the location of the leads with a single patient-use skin marker to assure correct replacement.5
Monitoring for dysrhythmias and ischemia
The best lead for monitoring dysrhythmias is V1; the next best is V6 (their bipolar equivalents are MCL1 and MCL6).4 Rhythms that can be distinguished in V1 but not in other leads include those with a widened QRS complex, such as right versus left ventricular rhythms; right and left bundle branch blocks; and differentiation of supraventricular rhythms with aberration from ventricular rhythms. Also, P waves are often visible in V1 when they're not visible in other leads because the exploring electrode is the one closest to the atria.
Select the monitoring lead based on the patient's dysrhythmia.
* Use lead V1 to distinguish ventricular from supraventricular rhythms with aberrant conduction.
* Use lead II or lead III to monitor atrial activity (atrial fibrillation and atrial flutter). If P waves are poorly visualized, use V1.
* Use lead V1 for primary monitoring if there's no history of or potential for atrial dysrhythmias and for patients with pacemakers.
Follow these monitoring guidelines:
* Monitor the QT interval for patients at high risk for QT prolongation and torsades de pointes.
* Monitor patients who were started on antiarrhythmic drugs known to cause QT prolongation and torsades de pointes (quinidine, procainamide, disopyramide, sotalol, ibutilide).
* Watch for adverse reactions to antiarrhythmic drugs, including new dysrhythmias.
* Watch for new onset bradycardias.
* Monitor the patient's serum electrolytes for abnormalities such as severe hypokalemia or hypomagnesemia.
Monitoring for ST-segment changes in patients at risk for myocardial ischemia is now possible. These patients include those admitted with unstable angina or chest pain, or postoperative patients with a history of heart disease. ST-segment monitoring is also used for patients after percutaneous coronary interventions. This modality can alert you to any reocclusion of target vessels.
Cardiac monitoring detects ST-segment changes at the start of ischemic events. Prompt intervention will help prevent myocardial injury and infarction. The AACN recommends leads III and V3 for ST-segment monitoring in patients with acute coronary syndromes.4 Remain aware of the following segment changes:
* T-wave inversion, alone or with ST-segment depression: A symmetrical arrowhead T-wave inversion in a lead that normally has an upright T wave is a hallmark of ischemia.
* ST-segment depression: This pattern is often seen in combination with a sharp angle at the junction of the ST segment and the T wave, indicating ischemia.
The hardest decision with these patients is to determine which lead to monitor. The wrong choice will result in missing an evolving event. Monitoring lead II, which is frequently chosen for dysrhythmia detection, could miss ischemia in the myocardium supplied by the right coronary artery, which will be best viewed in leads III and aVF. The choice of which lead to monitor is a crucial nursing decision.
In the ideal situation, the patient has evidence of prior ischemia and you can define his ischemic "fingerprint." The ischemic fingerprint is the unique pattern of ST-segment changes noted during a period of ischemia.6 This pattern may be observed during an episode of chest pain or with balloon inflation during angioplasty. Record which ECG lead demonstrates the most significant changes and give that information to the nurse who'll initiate monitoring.
If you don't know the patient's fingerprint, monitor leads III and V3, per AACN recommendations.4 If you have an idea which vessels are involved, you can consult an ECG lead chart to make the decision. (See What's my lead?)
Monitoring the ST segment can be challenging. A baseline must be established with the patient in a supine position. Movement and position changes will cause ST-segment variations and occasional alarms. The trick is to set the alarm parameters accurately and monitor for trends in the ST segment. Alarms may mean nothing if the patient is ambulating. When the trend is checked, no overall ST-segment change is evident. In cases in which the ischemia is real, checking the ST-segment trend will demonstrate a change in the ST segment overall.
|Table. What's my lead?|
Advances in technology and a large body of research have greatly enhanced our ability to monitor patients for dysrhythmias and ischemia. As a cardiac nurse, you must determine the best way to monitor the patient: Which leads are best and what is the purpose for monitoring. Making the right decisions can lead to accurate diagnosis, appropriate treatment, and improved patient outcomes.
Cardiac monitoring criteria
Patients with these conditions should be monitored for 24 to 48 hours:
* Low probability of myocardial infarction (MI), to rule out MI
* Any hemodynamically stable dysrhythmia
* Before and after coronary angiography in patients with stable angina and no heart failure
* Cardiac contusion without hemodynamic instability
* Neurologic changes such as transient ischemic attack or stroke
* Acute medical illness with stable cardiac disease and no ischemia
* Acute myocardial infarction without clinical signs of heart failure (Killip Class I)
* Postoperative patients with cardiac history but no active ischemia
* Post-permanent pacemaker placement
* Overdose or drug toxicity without dysrhythmia
* Syncope in patients without heart failure or respiratory failure
Patients with these conditions should be monitored for 48 to 72 hours:
* Unstable angina: rule out myocardial infarction
* Hemodynamically stable myocardial infarction
* Any hemodynamically unstable dysrhythmia, not including potentially lethal dysrhythmias that require continuous cardiac monitoring
* Before and after percutaneous coronary intervention in stable patients
* During initiation of antiarrhythmia agents
* Major ischemic or hemorrhagic stroke with potential for dysrhythmia
* Acute medical illness with cardiac disease
* Postoperative patients with angina, ST-segment and T-wave changes, myocardial ischemia on preoperative stress test, dysrhythmia, hypotension, or heart failure
* Respiratory failure as defined by hypoxemia, hypercapnea, uncompensated respiratory acidosis, clinical evidence of severe respiratory distress
* Overdose or drug toxicity with dysrhythmia or high potential for dysrhythmia
* Syncope in patients with heart failure or respiratory failure
* History of status epilepticus or seizure disorder and risk for sudden death