External Defibrillation and Cardioversion Protocol | Wellbeing

I. General Principles and Classifications

There are two primary methods of delivering the electrical shock based on timing. Asynchronous Defibrillation is used when the electrical impulse is discharged immediately upon pressing the button. In contrast, Synchronized Cardioversion involves the discharge of the impulse at a specifically selected moment—syncing with the R-wave on the ECG. This synchronization is crucial to avoid discharging electricity during the "vulnerable period" of the cardiac cycle (the peak of the T-wave), which could otherwise precipitate ventricular fibrillation or ventricular tachycardia. Defibrillation can be performed directly on the heart via an open thoracotomy (internal defibrillation) or through the chest wall (external defibrillation).

II. Indications and Contraindications

Indications: Asynchronous defibrillation is indicated for Ventricular Fibrillation (VF) or Pulseless Ventricular Tachycardia (VT). Synchronized cardioversion is indicated for unstable tachyarrhythmias (excluding sinus tachycardia) accompanied by hemodynamic compromise. The energy level selected for VF or pulseless VT depends on the patient's weight. These procedures must be performed rapidly; in cardiac arrest scenarios, anesthesia and anticoagulation are not required.

Contraindications: The procedure is contraindicated for Multifocal Atrial Tachycardia (MAT). It is also unsafe if the patient is in direct physical contact with another person, if the skin surface at the electrode site is wet, or if the patient has implanted devices (such as pacemakers or ICDs) directly under the intended paddle site (requires alternative pad placement).

III. Preparation

Personnel and Equipment: The procedure should be performed by a physician or nurse trained in defibrillation skills. The defibrillator unit consists of a capacitor charged by an AC source capable of discharging current with specific properties. Essential components include paddles (varying sizes for age groups), electrode cables (3-5 leads), and a monitor displaying the ECG and technical parameters. The device must feature controls for selecting Synchronized (SYN) or Asynchronous modes, Energy selection (Joules or Watts), a "CHARGE" button, and a "DISCHARGE" button.

Patient and Records: If the clinical situation permits (non-arrest), the patient should sign a consent form after receiving an explanation from the physician. Medical records must be maintained in accordance with Ministry of Health regulations.

IV. Procedure Steps

1. Pre-procedure Verification: Review the medical records to confirm indications, ensure no contraindications exist, and verify the consent form. Continue CPR (Cardiopulmonary Resuscitation) if the patient is in cardiac arrest.

2. Technique Execution: First, select the appropriate energy level and mode (Synchronized or Asynchronous). The energy setting depends on the patient's weight and the emergency physician's orders. Press the "CHARGE" button located on the front of the device or on the "APEX" paddle. Wait until an audible "beep" is heard and the screen displays the correct energy level along with the word "READY."

3. Delivering the Shock: Apply conductive gel to the defibrillator paddles. Place the paddles firmly directly onto the patient's bare chest: position the "STERNUM" paddle at the upper right chest (base of the heart) and the "APEX" paddle at the lower left chest (apex of the heart).

Monitor the ECG rhythm throughout the process. Crucially, ensure that no one is touching the patient. Once the area is clear, press the "DISCHARGE" buttons on both paddles simultaneously using your thumbs.

V. Monitoring and Complications

Post-Procedure Assessment: Immediately re-evaluate the patient following the ABC protocol (Airway, Breathing, Circulation).

Management of Complications: Potential complications include Ventricular Fibrillation (often due to selecting the wrong shock mode), which requires immediate restabilization. If Cardiac Arrest occurs, follow the standard ABC resuscitation protocol. Embolism is rare in children but possible. Acute Pulmonary Edema may occur due to left ventricular systolic dysfunction or transient atrial standstill; treat according to the pulmonary edema protocol. Skin burns at the electrode sites and hypotension should be managed according to their respective standard treatment protocols.