What is a concise, step‑by‑step ACLS algorithm that addresses all cardiac rhythms?

Streamlined ACLS Approach for All Cardiac Rhythms

The American Heart Association's ACLS algorithm divides all cardiac arrest rhythms into two pathways: shockable rhythms (VF/pulseless VT) requiring immediate defibrillation, and non-shockable rhythms (PEA/asystole) requiring immediate epinephrine—both built on the foundation of high-quality CPR with minimal interruptions. 1, 2

Universal Foundation: High-Quality CPR

All cardiac arrest management begins with immediate recognition and high-quality CPR, regardless of rhythm 1:

• Push hard and fast: Compress at least 2 inches (5 cm) depth at 100-120 compressions per minute 1
• Allow complete chest recoil after each compression 1
• Minimize interruptions: Keep pauses under 10 seconds for rhythm checks, defibrillation, or pulse checks 1, 2
• Avoid excessive ventilation: Use 30:2 compression-ventilation ratio without advanced airway, then 1 breath every 6 seconds (10 breaths/min) with continuous compressions once advanced airway placed 1
• Rotate compressors every 2 minutes or sooner if fatigued 1

The Two-Pathway Algorithm

Pathway 1: Shockable Rhythms (VF/Pulseless VT)

1. Immediate defibrillation with minimal interruption in compressions 1, 2:

   • Biphasic: 120-200 Joules (manufacturer recommendation)
   • Monophasic: 360 Joules 1

2. Resume CPR immediately for 2 minutes after shock delivery before rhythm check 1, 2

3. Establish IV/IO access and administer epinephrine 1 mg every 3-5 minutes 1

4. For refractory VF/pVT (after 2-3 shocks), consider antiarrhythmics 1:

   • Amiodarone: 300 mg IV/IO bolus, then 150 mg second dose, OR
   • Lidocaine: 1-1.5 mg/kg IV/IO, then 0.5-0.75 mg/kg second dose
   • Note: The 2018 update changed from favoring amiodarone to considering either drug equally, as neither improves long-term survival 1

5. Continue 2-minute CPR cycles with rhythm checks until ROSC or termination 1, 2

Pathway 2: Non-Shockable Rhythms (PEA/Asystole)

1. Immediate high-quality CPR without delay for rhythm analysis 1, 2

2. Administer epinephrine 1 mg IV/IO as soon as possible, then every 3-5 minutes 1, 2

3. Search for reversible causes (H's and T's) while continuing CPR 1:

   • H's: Hypovolemia, Hypoxia, Hydrogen ion (acidosis), Hypo-/hyperkalemia, Hypothermia
   • T's: Tension pneumothorax, Tamponade (cardiac), Toxins, Thrombosis (pulmonary), Thrombosis (coronary)

4. Rhythm check every 2 minutes during CPR cycles 1, 2

5. If rhythm changes to VF/pVT, switch to shockable pathway 1

Critical Airway Management Points

• Start with bag-mask ventilation using 30:2 ratio 1, 2
• Consider advanced airway (endotracheal tube or supraglottic device) when appropriate, but never interrupt compressions for prolonged periods 1, 2
• Confirm placement with waveform capnography immediately 1
• Monitor PETCO2: If <10 mmHg, improve CPR quality 1
• Once advanced airway placed, switch to continuous compressions with 1 breath every 6 seconds 1

Monitoring CPR Quality

Use physiologic parameters to optimize resuscitation 1:

• Quantitative waveform capnography: Target PETCO2 >10 mmHg (ideally 10-20 mmHg during CPR) 1
• Intra-arterial pressure monitoring if available: Target relaxation phase (diastolic) pressure >20 mmHg 1
• Abrupt sustained increase in PETCO2 (typically ≥40 mmHg) indicates ROSC 1

Recognizing Return of Spontaneous Circulation (ROSC)

Stop CPR and confirm ROSC when 1, 3:

• Pulse and blood pressure return
• Abrupt sustained increase in PETCO2 (typically >40 mmHg)
• Spontaneous arterial pressure waves with intra-arterial monitoring

Post-ROSC Management

Once ROSC achieved 2, 3:

• Maintain mean arterial pressure ≥65 mmHg with vasopressors if needed
• Target SpO2 92-98% to avoid both hypoxia and hyperoxemia
• Initiate targeted temperature management for all patients not following commands
• Do NOT routinely administer prophylactic antiarrhythmics after ROSC—no evidence supports improved survival 1, 3
• Exception: Consider prophylactic lidocaine during EMS transport when recurrent VF/pVT would be logistically challenging to treat 1, 3

Common Pitfalls to Avoid

• Never delay defibrillation to establish IV access or administer medications in shockable rhythms 2, 4
• Avoid prolonged pulse checks: If no definite pulse within 10 seconds, resume CPR 2, 4
• Don't interrupt compressions for advanced airway placement—use brief pauses only 1, 4
• Avoid excessive ventilation, especially with advanced airway (causes increased intrathoracic pressure and decreased venous return) 1, 4
• Don't treat compensatory sinus tachycardia post-ROSC with rate-control agents 3
• Never base treatment solely on rhythm without clinical context—assess the whole patient 1

Tachycardia With Pulse Algorithm (Periarrest)

For patients with tachycardia and pulse 1:

1. Assess stability: Is the patient unstable (altered mental status, chest pain, acute heart failure, hypotension, shock)? 1

2. If unstable: Proceed immediately to synchronized cardioversion 1

3. If stable, determine rhythm type 1:

   • Narrow-complex regular: Consider adenosine 6 mg rapid IV push, then 12 mg if needed 1
   • Wide-complex: Treat as VT until proven otherwise; consider antiarrhythmics (amiodarone, procainamide, or lidocaine) 1

4. Critical point: Heart rates <150 bpm are unlikely to cause instability unless ventricular dysfunction present—look for underlying causes 1