According to the European Resuscitation Council (ERC) guidelines, the management of cardiac arrest involves identifying the cardiac rhythm to determine whether defibrillation (shock) is indicated. Rhythms are classified as either shockable or non-shockable.
Shockable Rhythms
1. Ventricular Fibrillation (VF)
2. Pulseless Ventricular Tachycardia (VT)
Non-Shockable Rhythms
1. Asystole
2. Pulseless Electrical Activity (PEA)
Shockable Rhythms
1. Ventricular Fibrillation (VF)
Description: VF is a chaotic and disorganised rhythm originating in the ventricles, leading to ineffective quivering of the heart without any meaningful cardiac output.
ECG Characteristics:
- Irregular waveform.
- No identifiable P waves, QRS complexes, or T waves.
- Varying amplitude and frequency.
Management:
- Immediate Defibrillation:
- Deliver a shock at 150-200 joules (biphasic) or 360 joules (monophasic).
- If VF persists, continue CPR for 2 minutes and then re-assess the rhythm.
- Administer additional shocks as needed, escalating energy levels if possible.
- CPR: Perform high-quality chest compressions and ventilation.
- Medications: Administer epinephrine and amiodarone according to advanced life support (ALS) protocols.
2. Pulseless Ventricular Tachycardia (VT)
Description: Pulseless VT is a rapid, organised ventricular rhythm without sufficient cardiac output to produce a pulse.
ECG Characteristics:
- Regular, wide QRS complexes.
- Typically >100 bpm.
- No discernible P waves.
Management:
- Immediate Defibrillation:
- Deliver a shock at 150-200 joules (biphasic) or 360 joules (monophasic).
- If pulseless VT persists, continue CPR for 2 minutes and then re-assess the rhythm.
- Administer additional shocks as needed, escalating energy levels if possible.
- CPR: Perform high-quality chest compressions and ventilation.
- Medications: Administer epinephrine and amiodarone according to ALS protocols.
Non-Shockable Rhythms
1. Asystole
Description: Asystole is the complete absence of any electrical activity in the heart, resulting in a flatline on the ECG and no cardiac output.
ECG Characteristics:
- Flatline or nearly flatline.
- No P waves, QRS complexes, or T waves.
Management:
- CPR: Perform high-quality chest compressions and ventilation immediately.
- Medications: Administer epinephrine according to ALS protocols.
- Assess and Address Reversible Causes: Consider and treat potential reversible causes (e.g., hypoxia, hypovolemia, hyperkalemia, hypothermia, tension pneumothorax, tamponade, toxins, thrombosis).
2. Pulseless Electrical Activity (PEA)
Description: PEA is characterised by the presence of organised electrical activity on the ECG without a palpable pulse or effective cardiac output.
ECG Characteristics:
- Can appear as any organised rhythm (sinus rhythm, atrial fibrillation, etc.) without an associated pulse.
- Does not include VF or VT.
Management:
- CPR: Perform high-quality chest compressions and ventilation immediately.
- Medications: Administer epinephrine according to ALS protocols.
- Assess and Address Reversible Causes: Consider and treat potential reversible causes (e.g., hypoxia, hypovolemia, hyperkalemia, hypothermia, tension pneumothorax, tamponade, toxins, thrombosis).
Summary Table
| Rhythm | Classification | Initial Action | Defibrillation Energy |
|---|---|---|---|
| Ventricular Fibrillation (VF) | Shockable | Immediate defibrillation | 150-200 joules (biphasic) / 360 joules (monophasic) |
| Pulseless Ventricular Tachycardia (VT) | Shockable | Immediate defibrillation | 150-200 joules (biphasic) / 360 joules (monophasic) |
| Asystole | Non-shockable | Immediate CPR | Not applicable |
| Pulseless Electrical Activity (PEA) | Non-shockable | Immediate CPR | Not applicable |
Important Considerations
- High-Quality CPR: Regardless of the rhythm, high-quality chest compressions and effective ventilation are critical for patient survival.
- Reversible Causes (Hs and Ts): Always consider and treat reversible causes during the resuscitation effort:
- Hypoxia
- Hypovolemia
- Hypothermia
- Hypo-/Hyperkalemia
- Hydrogen ions (acidosis)
- Tension pneumothorax
- Tamponade (cardiac)
- Toxins
- Thrombosis (coronary or pulmonary)
By adhering to these guidelines, healthcare providers can effectively manage cardiac arrest, improve patient outcomes, and reduce the risk of complications.