AHA ACLS Cardiac Arrest Algorithm

The Adult Cardiac Arrest Algorithm (2025 AHA update) is a structured, cycle-based guideline developed by the American Heart Association to manage adult cardiac arrest. It focuses on continuous, high-quality resuscitation with minimal interruptions and coordinated team actions during emergencies.

The model follows a circular approach to repeated assessment and intervention, enabling rapid decision-making in cardiac arrest care. The algorithm improves workflow efficiency by guiding providers through organized steps of CPR, rhythm evaluation, and treatment delivery to enhance survival outcomes in critical cardiovascular emergencies.

Step-by-Step ACLS Algorithm for Cardiac Arrest

Step 1: Immediate Resuscitation After Cardiac Arrest Recognition

Immediate initiation of resuscitation is essential in cardiac arrest to maintain vital organ perfusion. High-quality CPR should begin without delay while preparing advanced life support equipment.

Essential Actions:

Start high-quality chest compressions immediately
Provide bag-mask ventilation with 100% oxygen
Attach monitor/defibrillator as soon as available
Do not delay CPR for equipment setup
Prioritize circulation and oxygen delivery

Step 2: Cardiac Rhythm Assessment After Monitoring Setup

Once monitoring is established, CPR is briefly paused to analyze the cardiac rhythm. This determines whether defibrillation is required or non-shockable arrest management should continue.

Clinical Priorities:

Pause CPR briefly for rhythm analysis
Identify VF/pulseless VT (Shockable rhythm)
Identify PEA/asystole (Non-shockable rhythm)
Decide on an immediate treatment pathway
Resume CPR immediately after assessment

Step 3: Defibrillation for VF or Pulseless Ventricular Tachycardia

Shockable rhythms such as VF or pulseless VT require immediate defibrillation to restore organized cardiac electrical activity. CPR must resume immediately after shock without delay or pulse check.

Defibrillation Protocol:

Deliver one immediate shock
Biphasic: 120-200 J (or manufacturer recommendation)
Monophasic: 360 J
Resume CPR immediately after shock
Do not perform a pulse check after defibrillation

Step 4: Two-Minute High-Quality CPR Following Shock or Non-Shockable Rhythm

After defibrillation or in non-shockable rhythms, continuous high-quality CPR for two minutes is critical to maintain perfusion and prepare for the next rhythm assessment.

CPR Performance Standards:

Continuous CPR for 2 minutes without interruption
Compression rate: 100-120/min
Depth: at least 2 inches (5 cm)
Allow full chest recoil and minimize pauses
Ventilation: 30:2 or continuous with advanced airway

Step 5: Medication Administration During Ongoing CPR

Drug therapy enhances resuscitation effectiveness. Epinephrine is administered in all cardiac arrest rhythms, while antiarrhythmics are used for refractory shockable rhythms.

Pharmacologic Interventions:

Epinephrine 1 mg IV/IO every 3-5 minutes
Establish IV or IO access early
Amiodarone 300 mg then 150 mg for VF/pVT
OR Lidocaine 1-1.5 mg/kg then 0.5-0.75 mg/kg
Continue medications during CPR cycles

Step 6: Advanced Airway Placement and Ventilation Control

Advanced airway management improves oxygenation and ventilation control during prolonged resuscitation. It enables uninterrupted compressions with reliable airway protection and monitoring.

Airway Management Measures:

Use an endotracheal tube or supraglottic airway
Confirm placement using waveform capnography
Deliver 1 breath every 6 seconds
Maintain continuous chest compressions
Optimize oxygenation and ventilation efficiency

Step 7: Continuous Monitoring of CPR Quality Using Capnography

CPR effectiveness must be continuously evaluated using end-tidal CO₂ monitoring. Low or decreasing values indicate poor perfusion and require immediate correction of compression quality.

Quality Assurance Measures:

Use waveform capnography (ETCO₂ monitoring)
Continuously assess compression effectiveness
Low ETCO₂ indicates inadequate CPR quality
Adjust compression depth and rate as needed
Minimize interruptions in chest compressions

Step 8: Rhythm Reassessment Every Two Minutes

Rhythm is reassessed every two minutes to guide ongoing management decisions, including defibrillation or continuation of CPR with medications and reversible cause evaluation.

Clinical Decision Steps:

Pause CPR every 2 minutes briefly
Check cardiac rhythm
Deliver shock for VF/pVT if present
Continue CPR for PEA/asystole
Administer epinephrine and evaluate causes

Step 9: Continuous Resuscitation Cycle Until Outcome

Resuscitation follows a continuous structured cycle of CPR, rhythm analysis, defibrillation, medications, and airway management until return of spontaneous circulation or termination of efforts.

Ongoing Resuscitation Strategy:

Repeat CPR and rhythm cycles continuously
Follow CPR → Rhythm check → Shock sequence
Administer drugs at recommended intervals
Maintain airway and oxygenation support
Continue until ROSC or termination decision

Advanced Airway Management in ACLS Cardiac Arrest

Advanced airway management in ACLS cardiac arrest involves securing and maintaining a patent airway to ensure adequate ventilation and oxygen delivery during resuscitation. It supports continuous chest compressions, improves respiratory control, and uses verified techniques for tube placement confirmation. Controlled ventilation is provided once the airway is established to optimize perfusion and outcomes.

Key Highlights:

Endotracheal intubation or a supraglottic airway is used for airway control
Provides a definitive method for airway protection and ventilation
Applied when bag-mask ventilation is not adequate
Placement confirmed using waveform capnography
Capnometry may be used if waveform capnography is unavailable
Ventilation delivered at 1 breath every 6 seconds (10/min)
Chest compressions remain continuous without interruption

H’s and T’s: Reversible Causes of Cardiac Arrest in ACLS

Reversible causes of cardiac arrest, known as the H’s and T’s, represent critical underlying conditions that must be rapidly identified and corrected during resuscitation. Addressing these factors improves the effectiveness of CPR and defibrillation, increases the likelihood of ROSC, and helps prevent ongoing or recurrent cardiac arrest during treatment.

H’s (Metabolic Causes)

Hypovolemia: Severe loss of blood or fluids leading to reduced circulation
Hypoxia: Inadequate oxygen supply to tissues
Hydrogen ion (Acidosis): Excess acid impairs cardiac function
Hypo-/Hyperkalemia: Abnormal potassium levels causing dangerous arrhythmias
Hypothermia: Critically low body temperature affecting heart activity

T’s (Mechanical and Toxic Causes)

Tension Pneumothorax: Air trapped in the chest compressing the lungs and heart
Cardiac Tamponade: Fluid around the heart, limiting cardiac output
Toxins: Drug overdose or poisoning affecting heart function
Thrombosis Pulmonary (PE): A blood clot blocking pulmonary circulation
Thrombosis Coronary (MI): Blockage of a coronary artery causing a heart attack

Return of Spontaneous Circulation (ROSC) in ACLS Cardiac Arrest

Return of Spontaneous Circulation (ROSC) occurs when effective cardiac activity resumes after resuscitation, restoring blood flow to vital organs. In the 2025 AHA ACLS algorithm, it indicates successful resuscitation and transition from active CPR to the post–cardiac arrest care management phase.

ROSC is identified by return of a palpable pulse, spontaneous breathing or improved respiratory effort, and rising end-tidal CO₂ levels. Immediate post-cardiac arrest care begins to stabilize the patient, support organ function, treat the underlying cause, and prevent further complications effectively.

Effective Execution of the ACLS Cardiac Arrest Algorithm

Timely and coordinated implementation of the ACLS Cardiac Arrest Algorithm is essential for improving patient survival during cardiac emergencies. High-quality CPR, early defibrillation, accurate rhythm assessment, and appropriate drug therapy work together to increase the chances of achieving return of spontaneous circulation (ROSC).

Identifying and treating reversible causes further increases resuscitation success and prevents recurrence. Proper application of the AHA ACLS algorithm ensures better outcomes in critical emergencies. For structured training and life-saving skill development, visit CPR VAM CPR Training Center.

FAQs

1. What is the AHA ACLS Cardiac Arrest Algorithm?

The AHA ACLS Cardiac Arrest Algorithm is a structured, step-by-step guide used by healthcare providers to manage cardiac arrest. It combines high-quality CPR, timely defibrillation, medication administration, advanced airway support, and identification of reversible causes to improve the chances of survival and recovery.

2. What are the steps in the ACLS cardiac arrest algorithm?

The ACLS cardiac arrest algorithm includes these key steps: start high-quality CPR immediately, check the rhythm to see if it’s shockable, deliver a shock if needed, resume CPR for 2 minutes, give epinephrine every 3–5 minutes, consider advanced airway placement, administer antiarrhythmic drugs if indicated, and identify and treat reversible causes (the H’s and T’s). Continue cycles of CPR and rhythm checks until return of spontaneous circulation (ROSC) or termination of efforts.

3. How do I know if a rhythm is shockable or non-shockable?

Shockable rhythms include ventricular fibrillation and pulseless ventricular tachycardia. Non-shockable rhythms are asystole and pulseless electrical activity. The treatment depends on this classification.

4. When should epinephrine be given in ACLS?

Epinephrine should be administered as soon as IV or IO access is established and then repeated every 3–5 minutes during cardiac arrest to help stimulate the heart and improve blood flow to vital organs.

5. What happens after Return of Spontaneous Circulation (ROSC)?

After ROSC, care focuses on stabilizing the patient by ensuring a clear airway, supporting breathing and blood pressure, monitoring vital signs, and preventing brain injury through treatments like targeted temperature management.