Basics of Defibrillation

Overview:

Defibrillation is the process of delivering a controlled electrical current through the heart during cardiac arrest to terminate an abnormal electrical rhythm.

Types of devices:

• Automated External defibrillator (AED).
• Internal defibrillator.
• Manual defibrillator.
• Semi-automated defibrillator.
• Implantable cardioverter-defibrillator (ICD).
• Wearable Defibrillators.

In this article we will cover the manual defibrillator.

Interface:

What is used to conduct the electrical current from the device to the patient.

• Hand-held paddle.
• Self-adhesive pads.

Positioning:

Conventional positions (anterolateral)

• One paddle is placed on the left fourth or fifth intercostal space on the midaxillary line.
• The second paddle is placed just to the right of the sternal edge on the second or third intercostal space.

Type of waveforms:

(depend on the device)

• Monophasic.
• Biphasic.

Factors that affect success rate:

• Early defibrillation.
• Energy selected.
• Electrode size.
• Paddle–skin coupling material.
• Number and time interval of previous shocks.
• Phase of ventilation.
• Distance between electrodes (size of the chest).

Indicatons:

• Ventricular fibrillation (VF).
• Pulseless Ventricular Tachycardia (pVT).

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Contraindications:

• Non shockable rhythms include:
  • Asystole.
  • Pulseless electrical activity.
• Patient presenting with signs of life.

Complications:

• Directly injuring myocardial cells.
• Inducing post-shock dysfunction.
• Refibrillation.
• Skin burns.
• Explosion.
• Transmitted shock to the operator.

Doses:

• 200 J for monophasic.
• 360 J for Biphasic.

Procedure (The ARC Guidelines 2016):

Required a very good communication and a trained team

C: Compressions Continue
O: Oxygen away (if free flowing BVM)
A: All others clear
C: Charging defibrillator
H: Hands off (compressor should say I’m safe)
E: Evaluating rhythm
D: Defibrillate or Disarm