What is the ACLS (Advanced Cardiovascular Life Support) protocol for managing asystole?

ACLS Protocol for Asystole

For asystole cardiac arrest, immediately begin high-quality CPR with chest compressions at least 100/min and depth of at least 2 inches, administer epinephrine 1 mg IV/IO every 3-5 minutes, secure an advanced airway, and aggressively search for and treat reversible causes—this rhythm carries a poor prognosis but survival is possible when reversible causes are identified early. 1, 2

Immediate Actions Upon Recognition

• Confirm true asystole by checking multiple leads to rule out fine ventricular fibrillation masquerading as asystole, and ensure proper electrode contact to avoid equipment artifact 1, 2
• Begin chest compressions immediately without delay—push hard (at least 2 inches/5 cm) and fast (100-120/min) with complete chest recoil and minimal interruptions 1, 3
• Establish IV/IO access as soon as feasible for medication administration 1, 2

Airway and Ventilation Management

• Secure an advanced airway (endotracheal tube or supraglottic device) without interrupting chest compressions 1, 3, 2
• Provide ventilation with 100% oxygen at 1 breath every 6-8 seconds (8-10 breaths/min) after advanced airway placement, with continuous uninterrupted chest compressions 1, 3
• Confirm proper airway placement using quantitative waveform capnography 1, 3
• Avoid excessive ventilation, which can impair venous return and worsen outcomes 1, 3

Pharmacologic Therapy

Epinephrine (Primary Medication)

• Administer epinephrine 1 mg IV/IO every 3-5 minutes as the cornerstone pharmacologic intervention 1, 2
• Continue epinephrine throughout the resuscitation effort as long as resuscitation continues 1

Atropine (No Longer Routinely Recommended)

• Atropine has been removed from the cardiac arrest algorithm as routine use during asystole is unlikely to provide therapeutic benefit 1
• Historical protocols recommended atropine 3 mg IV as a single full vagolytic dose, but current evidence does not support routine use 1, 2

CPR Quality Monitoring

• Rotate compressors every 2 minutes to prevent fatigue and maintain compression quality 1, 3
• Monitor CPR quality using quantitative waveform capnography with target PETCO₂ >10 mmHg 1, 3
• If PETCO₂ remains <10 mmHg, actively work to improve CPR quality 1
• Consider intra-arterial pressure monitoring if available, targeting relaxation phase pressure >20 mmHg 1

Rhythm Assessment Strategy

• Reassess rhythm every 2 minutes during brief pauses in CPR (less than 10 seconds) 1, 3
• If VF/VT develops at any point, immediately switch to the shockable rhythm algorithm and deliver defibrillation 1, 2
• Continue CPR immediately after rhythm checks unless ROSC is achieved 1

Search for Reversible Causes (H's and T's)

This is critically important in asystole, as reversible causes are relatively more common than in VF/VT arrests 1

The H's:

• Hypoxia: Ensure adequate oxygenation and ventilation 1, 2
• Hypovolemia: Consider empirical IV crystalloid bolus for suspected volume loss or sepsis; blood transfusion for severe hemorrhage 1, 2
• Hydrogen ion (acidosis): Address severe metabolic acidosis if present 2
• Hypo/hyperkalemia: Correct electrolyte abnormalities 1, 2
• Hypothermia: Rewarm if present; continue resuscitation until patient is rewarmed 3, 2

The T's:

• Tension pneumothorax: Perform needle decompression if clinically suspected 1
• Tamponade (cardiac): Consider echocardiography to assess for pericardial effusion 1
• Toxins: Treat specific toxicologic causes 1
• Thrombosis (pulmonary): Consider empirical fibrinolytic therapy if pulmonary embolism is presumed or known cause (Class IIa) 1
• Thrombosis (coronary): Consider acute coronary syndrome as underlying cause 1

Use of Echocardiography

• When available, echocardiography provides valuable information about intravascular volume status, cardiac tamponade, mass lesions, left ventricular contractility, and regional wall motion 1
• Can guide management decisions regarding fluid resuscitation and identification of reversible causes 1

Duration of Resuscitation

• Continue resuscitation for at least 20-30 minutes from time of collapse unless overwhelming reasons exist to believe efforts are futile 1, 2
• Continuously reassess for potentially reversible causes throughout the resuscitation 1, 2

What NOT to Do (Common Pitfalls)

• Do not attempt cardiac pacing in true asystole—it has no proven benefit except in cases of trifascicular block where P waves are visible, and delays effective CPR 1, 2
• Do not routinely administer calcium, magnesium, or sodium bicarbonate—these have no proven benefit in asystole and calcium may worsen ischemic injury 2
• Do not perform immediate countershock/defibrillation for confirmed asystole—this provides no benefit and delays effective CPR 4, 5
• Do not use ETCO₂ values alone to make termination of resuscitation decisions 3
• Do not perform prolonged pulse checks—if pulse is not definitely felt within 10 seconds, resume CPR immediately 3

Post-ROSC Care (If Achieved)

• Initiate post-cardiac arrest care immediately upon achieving ROSC 1
• Treat hypoxemia and hypotension aggressively 1, 3
• Diagnose and treat the underlying cause of cardiac arrest 1
• Consider therapeutic hypothermia for comatose patients (Class IIb for asystole) 1
• Maintain oxygenation and ventilation, avoiding both hypoxia and hyperoxia 3

Prognosis Considerations

• Asystole carries a much worse prognosis than VF/VT, with overall survival rates approximately 10-15% of VF/VT survival rates 1
• However, about 20% of eventual survivors present with non-VF/VT rhythms, so resuscitation should not be abandoned prematurely 1
• Asystole is commonly the end-stage rhythm following prolonged VF or PEA, which contributes to poor prognosis 1
• Witnessed arrest is an independent predictor of improved outcome 6