Obtaining an Electrocardiogram

Skill 15-4

Obtaining an Electrocardiogram

Electrocardiography measures the heart's electrical activity and is one of the most valuable and frequently used diagnostic tools. Impulses moving through the heart's conduction system create electric currents that can be monitored on the body's surface. Electrodes attached to the skin can detect these electric currents and transmit them to an instrument that produces a record of cardiac activity, the electrocardiogram (ECG). The data are graphed as waveforms (Figure 1). ECGs can be used to assess and diagnose patients with suspected arrhythmias, hypertension, coronary heart disease, and heart failure (Menzies-Gow, 2018) and to identify myocardial ischemia and infarction, rhythm and conduction disturbances, chamber enlargement, electrolyte imbalances, and drug toxicity.

The standard 12-lead ECG uses a series of electrodes placed on the extremities and the chest wall to assess the heart from 12 different viewpoints (leads) by attaching 10 cables with electrodes to the patient's limbs and chest: 4 limb electrodes and 6 chest electrodes (Figure 2). Each lead provides an electrographic snapshot of electrochemical activity of the myocardial cell membrane. The ECG device measures and averages the differences between the electrical potential of the electrode sites for each lead and graphs them over time, creating the standard ECG complex, called PQRST (Box 15-2). These electrodes provide views of the heart from the frontal plane as well as the horizontal plane. It is essential that connection or placement of the ECG electrodes/leads is accurate to prevent misdiagnosis (Bickerton & Pooler, 2019; Pearce, 2019). The ECG tracing needs to be clear to enable accurate and reliable interpretation.

An ECG is typically accomplished using a multichannel method. All electrodes are attached to the patient at once, and the machine prints a simultaneous view of all leads. It is important to reassure the patient that the leads just sense and record and do not transmit any electricity (Morton & Fontaine, 2018). The patient must be able to lie still and refrain from speaking to prevent body movement from creating artifacts in the electrical signal (Morton & Fontaine, 2018). Variations of the standard ECG include the exercise ECG (stress ECG) and the ambulatory ECG (Holter monitoring).

Interpreting the ECG requires the following actions:

Determining the rate
Determining the rhythm
Evaluating the P wave
Determining the duration of the PR interval
Determining the duration of the QRS complex
Evaluating the T wave
Determining the duration of the QT interval
Evaluating the ST segment
Evaluating any other components

Delegation Considerations

Obtaining an ECG is not delegated to assistive personnel (AP); in some facilities, technicians are trained to obtain an ECG. Depending on the state's nurse practice act and the organization's policies and procedures, this procedure may be delegated to licensed practical/vocational nurses (LPN/LVNs). The decision to delegate must be based on careful analysis of the patient's needs and circumstances as well as the qualifications of the person to whom the task is being delegated. Refer to the Delegation Guidelines in Appendix A.

Equipment

ECG machine
Recording paper
Disposable pregelled electrodes
Adhesive remover swabs
4 × 4 gauze pads
Skin cleanser and water, if necessary
PPE, as indicated
Bath blanket

Assessment

Review the patient's health record and care plan for information about the patient's need for an ECG. Assess the patient's cardiac status, including heart rate, blood pressure, and auscultation of heart sounds. If the patient is already connected to a cardiac monitor, remove the electrodes to accommodate the precordial leads and minimize electrical interference on the ECG tracing. Keep the patient away from objects that might cause electrical interference, such as equipment, fixtures, and power cords. Inspect the patient's chest for areas of irritation, skin breakdown, or excessive hair that might interfere with electrode placement.

Actual or Potential Health Problems and Needs

Many actual or potential health problems or issues may require the use of this skill as part of related interventions. An appropriate health problem or issue may include:

Impaired cardiac output
Acute pain
Activity intolerance

Outcome Identification and Planning

The expected outcomes to achieve are that an ECG is obtained without any complications, and the patient demonstrates an understanding of the need for and about the ECG.

Implementation

Action	Rationale
1. Verify the prescribed intervention for the ECG in the patient's health record.	Verifying the prescribed intervention ensures that the correct intervention is administered to the right patient.
2. Gather all equipment.	Assembling equipment provides for an organized approach to the task.
3. Perform hand hygiene and put on PPE, if indicated.	Hand hygiene and PPE prevent the spread of microorganisms. PPE is required based on transmission precautions.
4. Identify the patient.	Identifying the patient ensures the right patient receives the intervention and helps prevent errors.
5. Close the curtains around the bed and close the door to the room, if possible. As you set up the machine to record a 12-lead ECG, explain to the patient what you are going to do and why. Tell the patient that the test records their heart's electrical activity, and it may be repeated at certain intervals. Emphasize that no electrical current will enter their body. Tell the patient the test typically takes about 5 minutes. Ask the patient about allergies to adhesive, as appropriate.	This ensures the patient's privacy. Explanation relieves anxiety and facilitates engagement. Possible allergies may exist related to the adhesive on ECG leads.
6. Place the ECG machine close to the patient's bed and plug the power cord into the wall outlet.	Having equipment available saves time and facilitates accomplishment of the task.
7. If the bed is adjustable, raise it to a comfortable working height (VHACEOSH, 2016).	Having the bed at the proper height prevents back and muscle strain on the part of the nurse.
8. Position the patient in a semi-recumbent position (head of the bed at approximately 45 degrees) or supine position in the center of the bed with their arms at their sides (Campbell et al., 2017). Expose the patient's arms and legs, and drape appropriately. Encourage the patient to relax their arms and legs. Ensure their wrists do not touch their waist. Make sure their feet do not touch the bed's footboard.	Proper positioning helps promote patient comfort and will produce a better tracing. Proper positioning, supporting the patient's limbs on the bed, and relaxing their arms and legs minimizes muscle tension and trembling and resulting electrical interference (Campbell et al., 2017). The ECG appearance can be affected by the angle of incline of the torso at the time of the recording (Campbell et al., 2017). Document the patient's position so that subsequent tracings are performed with the patient in the same position (Campbell et al., 2017; Garcia, 2015; Morton & Fontaine, 2018).
9. If necessary, prepare the skin for electrode placement (AACN, 2018). If an area is excessively hairy, clip the hair (AACN, 2018; Oster, n.d.) or shave the hair with a single-use razor (Campbell et al., 2017), according to facility policy. Clean excess oil or other substances from the skin with a skin cleanser and water. Use a gauze pad to vigorously rub and dry the skin.	Shaving may cause microabrasions on the skin, possibly resulting in portals of entry for microorganisms. Oils and excess hair interfere with electrode contact and function. Rubbing with gauze abrades and dries the skin. Proper skin preparation is essential to reduce artifacts in and increase quality of the ECG tracing (AACN, 2018; Campbell et al., 2017; Garcia, 2015; Oster, n.d.).
10. Apply the limb electrodes (Figure 3). Peel the contact paper off the self-sticking disposable electrode and apply directly to the prepared site, as recommended by the manufacturer. Connect the limb lead wires to the electrodes. The tip of each lead wire is lettered and color coded for easy identification. The white, or RA, lead goes to the right arm, just above the wrist bone; the green, or RL, lead to the right leg, just above the ankle bone; the red, or LL, lead to the left leg, just above the ankle bone; and the black, or LA, lead to the left arm, just above the wrist bone. Refer to Figure 2 for electrode placement.	Use of recommended standard sites for limb electrodes is essential to obtain an accurate recording (Campbell et al., 2017; Garcia, 2015; Morton & Fontaine, 2018).
11. Expose the patient's chest. Apply the chest electrodes (Figure 4A). Peel the contact paper off the self-sticking, disposable electrode and apply them directly to the prepared site, as recommended by the manufacturer. Connect the chest lead wires to the electrodes (Figure 4B). The tip of each lead wire is lettered and color coded for easy identification. The V₁ to V₆ leads are applied to the chest. Position chest electrodes as follows (refer to Figure 2): V₁ (red): Fourth intercostal space at right sternal border V₂ (yellow): Fourth intercostal space at left sternal border V₃ (green): Exactly midway between V₂ and V₄ V₄ (blue): Fifth intercostal space at the left midclavicular line V₅ (orange): Left anterior axillary line, same horizontal plane as V₄ and V₆ V₆ (purple): Left midaxillary line, same horizontal plane as V₄ and V₅	Proper lead placement is necessary for accurate test results (AACN, 2018; Campbell et al., 2017; Garcia, 2015; Morton & Fontaine, 2018).
12. After the application of all the leads (Figure 5), ensure that the cables are not pulling on the electrodes or lying over each other. Make sure the paper-speed selector is set to the standard 25 mm/sec and that the machine is set to full voltage (10 mm/mV) (Menzies-Gow, 2018).	Lack of pulling and tension minimizes electrical artifacts and improves quality and accuracy of the ECG. The correct paper speed affects the timing of the ECG with respect to measurement of rate and duration of intervals (Garcia, 2015). The machine will record a normal standardization mark—a square that is the height of 2 large squares or 10 small squares on the recording paper.
13. Enter the appropriate patient identification data into the machine. Depending on facility policy, enter the patient's name, health record number, and age and biologic sex.	This allows for proper identification of the ECG strip. The ECG device requires minimum data input of age and biologic sex to correctly analyze the data (Garcia, 2015).
14. Ask the patient to relax and breathe normally. Instruct the patient to lie still and not to talk while the ECG is being recorded.	Lying still and not talking avoids resulting artifacts in the electrical signal, producing a better tracing (Campbell et al., 2017; Morton & Fontaine, 2018).
15. Press the AUTO or START button. Observe the tracing quality (Figure 6). The machine will record all 12 leads automatically, recording 3 consecutive leads simultaneously. Some machines have a display screen so you can preview waveforms before the machine records them on paper. Adjust the waveform, if necessary. If any part of the waveform extends beyond the paper when you record the ECG, adjust the normal standardization to half-standardization and repeat. Note this adjustment on the ECG strip, because this will need to be considered in interpreting the results.	Observation of tracing quality allows for adjustments to be made, if necessary. Notation of adjustments ensures accurate interpretation of results.
16. When the machine finishes recording the 12-lead ECG (Figure 7), remove the electrodes and clean the patient's skin, if necessary, with adhesive remover for sticky residue.	Removal and cleaning promote patient comfort.
17. After disconnecting the lead wires from the electrodes, dispose of the electrodes. Return the patient to a comfortable position. Lower the bed height and adjust the head of the bed to a comfortable position.	Proper disposal deters the spread of microorganisms. Positioning with head adjustment promotes patient comfort. Lowering the bed height promotes patient safety.
18. If not done electronically from data entered into the machine, label the ECG with the patient's name, date of birth, location, date and time of recording, and other relevant information (such as symptoms that occurred during the recording). Note any deviations to the standard approach to the recording, such as alternative placement of leads (see Special Considerations below).	Accurate labeling ensures the ECG is recorded for the correct patient as well as accurate and reliable interpretation.
19. Clean the ECG machine per facility policy. Clean reusable ECG cables and clips, according to facility policy; dispose of single-use ECG cables and clips.	Cleaning equipment between each patient use decreases the risk for transmission of microorganisms. Use non-bleach-based cleaning wipes to avoid deterioration of the wires (Bloe, 2021). Even after cleaning, the presence of microorganisms on reusable ECG lead wires increases the risk of transmission between patients, increasing the risk of health care-associated infections (Bloe, 2021). The use of single-use ECG leads reduces the risk of infection (Bloe, 2021).
20. Remove additional PPE, if used. Perform hand hygiene.	Proper removal of PPE reduces the risk for infection transmission and contamination of other items. Hand hygiene prevents transmission of microorganisms.

Evaluation

The expected outcomes have been met when an ECG has been obtained without any complications, and the patient has demonstrated an understanding of the need for and about the ECG.

Documentation

Guidelines

Document significant assessment findings, the date and time that the ECG was obtained, and the patient's response to the procedure. Label the ECG recording with the patient's name; room number; and facility identification number, if this was not done by the machine. Also record the date, time, and the patient's position as well as any appropriate clinical information on the ECG, such as blood pressure measurement, if the patient was experiencing chest pain. Record any deviations to the standard approach to the recording, such as alternative placement of leads (see Special Considerations below).

Sample Documentation

Developing Clinical Reasoning and Clinical Judgment

Unexpected Situations and Associated Interventions

Artifact appears on the tracing: An artifact may be due to loose electrodes or patient movement. Reassess the electrode connections. Ensure the ECG electrodes have not expired and are not dry; change the electrodes, if necessary. Ask the patient to lie extremely still. Consider additional skin preparation; refer to Step 9 in the Skill. Redo the ECG, if necessary.
Minimal complexes are seen: This may be due to extreme bradycardia. Run longer strips.

Special Considerations

Nurses must be familiar with the particular equipment in use; accuracy of the information is dependent on following the specifications of the manufacturer (Garcia, 2015). Some manufacturers may use different color combinations for the precordial leads; refer to the instructions for the particular equipment in use (Menzies-Gow, 2018).
The standard limb electrode locations are slightly proximal (just above) to the wrist and ankle bones (Campbell et al., 2017). Limb electrodes may be placed on the inside or outside aspects of the patient's wrist and ankle. Allow patients to position themselves comfortably, and then use the most accessible aspect for electrode placement. Do not obtain recordings from any other limb position unless there is a clinical reason, such as an amputation, surgical wounds, or burns. In patients with amputations, it is important to place the electrodes in the same position bilaterally (Garcia, 2015). Upper arms and upper legs may be used as alternative sites in these situations. ECGs recorded using any other limb position or precordial positions must be labeled to account for changes that might affect the interpretation and clinical decisions made (Campbell et al., 2017; Garcia, 2015).
Limb electrodes must not be placed on the torso to avoid significant alteration to the recorded information (Campbell et al., 2017).
To position the chest leads (V₁ to V₆) correctly, it is important to be able to accurately locate the relevant intercostal spaces (Campbell et al., 2017).
For female patients, place the V₄ electrode, as well as V₅ and V₆ as necessary, under the breast tissue as close to the chest wall as possible (Campbell et al., 2017; Garcia, 2015). In a large-breasted patient, you may need to displace the breast tissue laterally and/or superiorly.
Skin preparation is essential to ensure optimal electrode contact; a significant amount of dry or dead skin cells, grease, sweat, or hair can negatively affect the quality of the ECG recording (Menzies-Gow, 2018).
If it is necessary to adapt the recording techniques for an individual patient's circumstances, clearly describe the adaptations on the hard copy of the recording and in the electronically stored ECG (Campbell et al., 2017).

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Skill 15-4