What are the recommended steps for performing advanced cardiac life support (ACLS) in cardiac arrest?

Advanced Cardiac Life Support (ACLS) for Cardiac Arrest

Follow the 2020 American Heart Association Adult Cardiac Arrest Algorithm as your primary framework, emphasizing immediate high-quality CPR, early rhythm assessment, prompt defibrillation for shockable rhythms, and systematic drug therapy while continuously searching for reversible causes. 1

Initial Response and CPR Quality

When cardiac arrest is confirmed (unresponsive, no breathing or only gasping, no pulse):

• Start CPR immediately with cycles of 30 compressions to 2 breaths
• Compression technique: Push hard (at least 2 inches/5 cm depth) and fast (100-120/min)
• Allow complete chest recoil between compressions
• Minimize interruptions in compressions (no more than 10 seconds)
• Change compressor every 2 minutes or sooner if fatigued
• Avoid excessive ventilation 1

Rhythm Assessment and Defibrillation

Check rhythm every 2 minutes:

For VF/Pulseless VT (Shockable Rhythms):

• Deliver one shock immediately
  • Biphasic: 120-200 Joules initially (use manufacturer recommendation; if unknown, use maximum available)
  • Monophasic: 360 Joules
  • Second and subsequent doses should be equivalent or higher 1
• Resume CPR immediately for 2 minutes after shock delivery
• Do not pause to check rhythm or pulse after shock
• Continue this cycle until ROSC or rhythm changes 1

For Asystole/PEA (Non-Shockable Rhythms):

• Resume CPR immediately for 2 minutes
• No shock indicated
• Focus on high-quality compressions and reversible causes 1

Drug Therapy

Establish IV or IO access as soon as feasible without interrupting CPR:

Epinephrine:

• Dose: 1 mg IV/IO every 3-5 minutes
• For non-shockable rhythms: Give as soon as access obtained
• For shockable rhythms: Give after initial defibrillation attempts 1

Antiarrhythmics (for refractory VF/pVT):

• Amiodarone: 300 mg IV/IO bolus first dose, then 150 mg second dose
• OR Lidocaine (if amiodarone unavailable): 1-1.5 mg/kg first dose, then 0.5-0.75 mg/kg second dose 1

Advanced Airway Management

Consider advanced airway placement without interrupting high-quality compressions:

• Options: Endotracheal intubation or supraglottic advanced airway
• Use waveform capnography or capnometry to confirm and continuously monitor ET tube placement
• Once advanced airway placed: Give 1 breath every 6 seconds (10 breaths/min) with continuous chest compressions (no pauses for breaths) 1

This represents a critical shift from the 30:2 ratio—compressions become truly continuous once an advanced airway is secured.

Reversible Causes (H's and T's)

Systematically search for and treat reversible causes throughout resuscitation:

The H's:

• Hypovolemia - fluid resuscitation
• Hypoxia - oxygenation/ventilation
• Hydrogen ion (acidosis) - consider bicarbonate if prolonged arrest
• Hypo-/hyperkalemia - check electrolytes, treat accordingly
• Hypothermia - rewarm if present 1

The T's:

• Tension pneumothorax - needle decompression
• Tamponade, cardiac - pericardiocentesis
• Toxins - antidotes as appropriate
• Thrombosis, pulmonary - consider thrombolytics
• Thrombosis, coronary - consider PCI/thrombolytics 1

Recognition of ROSC

Stop CPR and assess if any of these occur:

• Palpable pulse and measurable blood pressure
• Abrupt sustained increase in ETCO₂ (typically ≥40 mmHg)
• Spontaneous arterial pressure waves on intra-arterial monitoring 1

The ETCO₂ rise is often the earliest indicator of ROSC and can be detected without interrupting compressions.

Key Pitfalls to Avoid

Common errors that reduce survival:

1. Inadequate compression depth or rate - Most providers compress too shallow; use feedback devices when available
2. Excessive interruptions - Every pause reduces coronary perfusion pressure; keep pauses under 10 seconds
3. Hyperventilation - Excessive ventilation increases intrathoracic pressure and decreases venous return
4. Delayed defibrillation - For VF/pVT, time to first shock is critical; defibrillate immediately when rhythm identified
5. Premature termination - Continue resuscitation while reversible causes remain untreated 1, 2

Updated Considerations from 2025 Guidelines

The 2025 AHA guidelines 2 emphasize that higher first-shock energy settings (≥200 J) are preferable for cardioversion of atrial fibrillation/flutter, though this applies to peri-arrest rather than cardiac arrest scenarios. The guidelines also discourage head-up CPR outside rigorous clinical trials and note that ETCO₂ should not be used in isolation to terminate resuscitation efforts.

The evidence consistently supports this algorithmic approach across multiple international guidelines 3, 4, with the core principles remaining: immediate recognition, high-quality CPR, early defibrillation when indicated, appropriate medications, advanced airway management, and relentless pursuit of reversible causes. These interventions, delivered systematically and without delay, provide the best opportunity for survival with good neurological outcomes.