What is the AHA ACLS algorithm for managing an adult in cardiac arrest with ventricular tachycardia or ventricular fibrillation?

AHA ACLS Algorithm for Ventricular Tachycardia and Ventricular Fibrillation

Immediately begin high-quality chest compressions at 100-120/min with depth of at least 2 inches (5 cm) and deliver one shock as soon as VF/pulseless VT is identified, then resume CPR for 2 minutes without pausing to check rhythm. 1, 2

Initial Recognition and CPR

• Check for responsiveness and pulse simultaneously within 10 seconds—if no definite pulse is felt, start CPR immediately, as pulse checks are unreliable even among trained providers 2, 3
• Activate the emergency response system immediately while beginning chest compressions 1
• Perform 30 compressions followed by 2 breaths until an advanced airway is placed, maintaining compression rate of 100-120/min and depth of at least 2 inches 2, 3
• Allow complete chest recoil between compressions and minimize interruptions to less than 10 seconds, as any pause reduces perfusion pressure 2, 3
• Change compressor every 2 minutes or sooner if fatigued to maintain compression quality 2, 3

Defibrillation Protocol

Early defibrillation with concurrent high-quality CPR is critical to survival when cardiac arrest is caused by VF or pulseless VT. 1

• Deliver one shock immediately when VF/pulseless VT is identified—use 120-200 Joules for biphasic defibrillators (or manufacturer recommendation) or 360 Joules for monophasic devices 2, 3, 4
• Resume CPR immediately for 2 minutes after the shock without pausing to check rhythm or pulse 1, 2, 3
• Use a single-shock strategy (as opposed to stacked shocks) for defibrillation 1
• Charge the defibrillator during chest compressions to minimize peri-shock pauses, as shorter pauses are associated with higher survival rates 4

The evidence strongly supports immediate resumption of compressions after defibrillation. While some concern exists that chest compressions immediately after shock could induce recurrent VF, the benefit of CPR in providing myocardial blood flow outweighs any theoretical risk 1.

Medication Administration

Establish IV or IO access during CPR without interrupting compressions. 2, 3

Epinephrine

• Administer epinephrine 1 mg IV/IO every 3-5 minutes throughout the resuscitation 1, 2, 3
• Administration of epinephrine with concurrent high-quality CPR improves survival, particularly in patients with nonshockable rhythms 1

Antiarrhythmic Therapy for Refractory VF/pVT

For shock-refractory VF/pVT (persisting after 1 or more shocks), administer amiodarone as the first-line antiarrhythmic. 1, 3

• Amiodarone 300 mg IV/IO as the first dose, followed by 150 mg if VF/pVT recurs 3
• Amiodarone improved hospital admission rates compared to placebo and lidocaine, though survival to discharge was not significantly different 1

If amiodarone is unavailable, use lidocaine as an alternative:

• Lidocaine 1-1.5 mg/kg IV/IO as initial dose, followed by 0.5-0.75 mg/kg 3
• Lidocaine was less effective than amiodarone in improving hospital admission rates but showed no difference in survival to discharge 1

Critical caveat: Establishing vascular access for drug administration should never compromise the quality of CPR or timely defibrillation, which are the interventions proven to improve survival 1. The optimal timing of drug administration in relation to shock delivery is not definitively known 1.

Advanced Airway Management

• Place endotracheal tube or supraglottic airway when feasible without prolonged interruption of compressions 2, 3
• Confirm placement with waveform capnography—this is the gold-standard verification method 2, 3
• After advanced airway placement, deliver 1 breath every 6 seconds (10 breaths/min) with continuous chest compressions (no pauses for ventilation) 1, 2, 3
• PETCO2 <10 mmHg suggests inadequate CPR quality 3

Rhythm Checks and Subsequent Shocks

• Check rhythm every 2 minutes during brief pauses in compressions 2, 3
• If VF/pVT persists, deliver another shock and immediately resume CPR for 2 minutes 2, 3
• Continue epinephrine every 3-5 minutes and consider repeat antiarrhythmic dosing 2, 3
• Recent evidence suggests escalating energy (200-300-360 J) may be more effective than fixed energy for refractory VF, particularly after the second shock 5

Reversible Causes (H's and T's)

Systematically evaluate and treat reversible causes during resuscitation: 3

The 4 H's:

• Hypovolemia—administer fluid boluses 3
• Hypoxia—ensure adequate oxygenation and ventilation 3
• Hydrogen ion (acidosis)—consider sodium bicarbonate for severe metabolic acidosis 3
• Hypo-/hyperkalemia—treat electrolyte abnormalities aggressively 3
• Hypothermia—initiate active rewarming 3

The 4 T's:

• Tension pneumothorax—perform needle decompression followed by chest tube 3
• Tamponade (cardiac)—perform emergent pericardiocentesis 3
• Toxins—give specific antidotes (e.g., naloxone for opioids) 3
• Thrombosis (pulmonary or coronary)—consider thrombolysis or emergent cardiac catheterization 3

Recognition of ROSC

Look for these indicators during rhythm checks: 2, 3

• Palpable pulse and measurable blood pressure 2, 3
• Abrupt sustained increase in PETCO2 ≥40 mmHg—this is the most reliable intra-arrest indicator of ROSC 2, 3
• Spontaneous arterial pressure waves on invasive monitoring 2, 3

Special Considerations for Pregnancy

In pregnant patients with VF/pulseless VT, immediate defibrillation takes priority over all other interventions, including perimortem cesarean section. 6

• Use standard ACLS defibrillation doses without modification 6
• Perform manual left lateral uterine displacement to relieve aortocaval compression 6
• Position compressions slightly higher on the sternum to account for elevated diaphragm 6
• Consider perimortem cesarean delivery within 4-5 minutes only if ROSC is not achieved after initial resuscitation efforts 6

COVID-19 Modifications

For suspected or confirmed COVID-19 patients 1:

• All rescuers must wear appropriate PPE for aerosol-generating procedures (N95 respirator, gown, gloves, eye protection) before initiating CPR 1
• Use HEPA filters on all ventilation devices 1
• Defibrillate as soon as indicated when providers are wearing appropriate PPE 1

Common Pitfalls to Avoid

• Do not perform pulse checks immediately after defibrillation—resume CPR for 2 minutes first 1, 2
• Do not delay defibrillation to establish IV access or administer medications—early defibrillation is the most effective single intervention 1, 3
• Do not use precordial thump as first-line treatment—it rarely results in ROSC and is more often associated with rhythm deterioration 7
• Do not pause compressions for ventilation after advanced airway placement—continue compressions continuously 2, 3
• Do not use stacked shocks—deliver single shocks followed by 2 minutes of CPR 1