CARDIAC ARREST ALGORITHM (ACLS)
The Cardiac Arrest Algorithm is a structured, evidence-based approach to managing patients in cardiac arrest. It emphasizes the importance of high-quality CPR, early defibrillation (when applicable), and effective medication administration.
Why It’s Important:
Standardized approach improves survival outcomes. Ensures rapid recognition and treatment of cardiac arrest. Incorporates early defibrillation, medication therapy, and post-resuscitation care.
INITIAL STEPS: IMMEDIATE RESPONSE
Step 1: Assess the Patient 
Check for responsiveness – Tap the patient and shout. Assess breathing and pulse (simultaneously for no more than 10 seconds). If the patient is unresponsive and has no normal breathing (or only gasping):
- Activate the emergency response system (Call 911/Code Blue).
- Start CPR immediately!
Step 2: Begin CPR 
Start chest compressions IMMEDIATELY:
Compression-to-ventilation ratio (if no advanced airway): 30:2 Compression rate: 100-120 per minute Compression depth: At least 2 inches (5 cm) in adults Minimize interruptions – Pauses <10 seconds!
If an advanced airway is placed (ETT/LMA): Give 1 breath every 6 seconds (10 breaths per minute). Continue chest compressions continuously without pausing for ventilations.
High-quality CPR is the MOST important factor in cardiac arrest survival!
Step 3: Attach a Cardiac Monitor/Defibrillator 
- As soon as available, attach defibrillator pads and assess the rhythm.
- The monitor will show one of four cardiac arrest rhythms.
RHYTHM ANALYSIS: DIFFERENTIATING CARDIAC ARREST RHYTHMS
The monitor will display one of four cardiac arrest rhythms:
Rhythm Type Definition
Ventricular Fibrillation (VF) A chaotic, disorganized electrical activity in the ventricles.
Pulseless Ventricular Tachycardia (pVT) A rapid, regular heartbeat from the ventricles, but no pulse.
Asystole Complete absence of electrical activity (flatline).
Pulseless Electrical Activity (PEA) Electrical activity is present, but no palpable pulse.
Determine whether the rhythm is SHOCKABLE or NON-SHOCKABLE.
SHOCKABLE RHYTHMS: VF/pVT (DEFIBRILLATION REQUIRED)
If the rhythm is VF or Pulseless VT:
Deliver an IMMEDIATE Shock (Defibrillation)
- First shock: 120-200 J (biphasic) or 360 J (monophasic).
Resume CPR IMMEDIATELY (for 2 minutes) after shock
- Do NOT check pulse right after the shock.
- Give continuous compressions.
Reassess Rhythm & Deliver Additional Shocks (if indicated)
- If still in VF/pVT, shock again!
Administer Epinephrine (1 mg IV/IO) every 3-5 minutes
- Start after the second shock.
Administer an Antiarrhythmic (If VF/pVT persists after multiple shocks)
- Amiodarone: 300 mg IV/IO first dose, followed by 150 mg IV/IO if needed.
- Lidocaine (alternative): 1-1.5 mg/kg IV/IO first dose, then 0.5-0.75 mg/kg IV/IO.
Key Takeaway: Continue cycles of CPR → Shock → Medications → Rhythm Check until ROSC or termination of resuscitation.
NON-SHOCKABLE RHYTHMS: Asystole & PEA (NO DEFIBRILLATION) 
If the rhythm is Asystole or PEA:
Continue High-Quality CPR (for 2 minutes).
Administer Epinephrine 1 mg IV/IO every 3-5 minutes.
Identify & Treat Reversible Causes (Hs & Ts).
Reassess Rhythm Every 2 Minutes
- If the patient remains in asystole/PEA, continue CPR and epinephrine.
- If the rhythm converts to VF/pVT, switch to the shockable rhythm algorithm.
Key Takeaway: In non-shockable rhythms, CPR and identifying the cause (Hs & Ts) are the main priorities!
REVERSIBLE CAUSES OF CARDIAC ARREST: THE “Hs & Ts”
Cardiac arrest is often caused by reversible conditions that MUST be identified and treated.
Hs: Causes Related to Metabolic & Circulatory Issues
| H Causes | Description |
|---|---|
| Hypovolemia | Severe blood or fluid loss. |
| Hypoxia | Low oxygen levels. |
| Hydrogen Ion (Acidosis) | Severe metabolic or respiratory acidosis. |
| Hyperkalemia/Hypokalemia | Potassium imbalances affecting cardiac function. |
| Hypothermia | Core body temperature too low (<30°C or 86°F). |
Ts: Causes Related to Structural or Toxic Issues
| T Causes | Description |
|---|---|
| Tension Pneumothorax | Air trapped in the chest collapses a lung. |
| Tamponade (Cardiac) | Fluid around the heart restricts pumping. |
| Toxins (Overdose, Poisoning) | Drug overdoses, especially opioids. |
| Thrombosis (Pulmonary or Coronary) | Blood clots in the lungs (PE) or heart (MI). |
Key Takeaway: If you do not treat the underlying cause, CPR alone will not be effective!
POST-RESUSCITATION CARE (AFTER ROSC)
If the patient regains a pulse (Return of Spontaneous Circulation – ROSC), immediate post-arrest care is critical!
Optimize Ventilation & Oxygenation
- Target SpO₂ 94-99%
- Avoid excessive ventilation (goal ETCO₂ 35-45 mmHg).
Manage Blood Pressure
- Maintain SBP >90 mmHg using fluids or vasopressors.
Consider Targeted Temperature Management (TTM)
- Cooling the body to 32-36°C helps prevent brain injury.
Identify & Treat the Underlying Cause
- Obtain ECG, cardiac enzymes, CT scan if needed.
Key Takeaway: Post-cardiac arrest care improves neurological function and long-term survival!
SUMMARY OF THE CARDIAC ARREST ALGORITHM
SHOCKABLE RHYTHMS (VF/pVT)
Shock immediately CPR for 2 minutes Reassess rhythm → If shockable, shock again! Epinephrine (1 mg IV/IO every 3-5 min) Antiarrhythmics (Amiodarone or Lidocaine) if needed
NON-SHOCKABLE RHYTHMS (Asystole/PEA)
CPR for 2 minutes Epinephrine (1 mg IV/IO every 3-5 min) Treat reversible causes (Hs & Ts) Reassess rhythm every 2 minutes
Continue cycles until ROSC or termination of resuscitation.
FINAL TAKEAWAYS: MASTERING CARDIAC ARREST MANAGEMENT
High-quality CPR is the cornerstone of survival. Shock promptly for VF/pVT – defibrillation saves lives! Epinephrine is essential for both shockable and non-shockable rhythms. Identify and treat reversible causes (Hs & Ts). Post-resuscitation care optimizes outcomes after ROSC.
Takeaway: The Cardiac Arrest Algorithm provides a life-saving, structured approach—every healthcare provider must master it!