What is the treatment for ventricular fibrillation in adults?

Treatment of Ventricular Fibrillation in Adults

Immediate defibrillation is the definitive treatment for ventricular fibrillation and must be delivered without delay, as survival decreases substantially with each passing minute. 1

Immediate Defibrillation Protocol

The first three shocks should be delivered in rapid succession using energies of 200 J, 200 J, and 360 J for monophasic waveforms, with minimal interruption between attempts. 1

• Over 80% of successful defibrillations occur within the first three shocks 1
• The interval between the third and fourth shocks should not exceed 2 minutes 1
• Check for a pulse only if the rhythm changes to one compatible with cardiac output; otherwise continue immediate defibrillation 1
• Biphasic waveforms may allow lower energy requirements and are acceptable if shown to have equal or greater efficacy 1

A critical pitfall: Do not delay defibrillation for intubation, IV access, or drug administration—these interventions come after the initial shock sequence. 2

Cardiopulmonary Resuscitation Between Shocks

After the first three unsuccessful shocks, perform 2 minutes of high-quality CPR (≥100 compressions/minute) before the next defibrillation attempt. 1, 3

• CPR is essential for restoring a perfusing rhythm after termination of prolonged VF 4
• Maintain chest compressions with minimal interruptions (≤15 seconds between shocks) 3
• CPR improves myocardial and cerebral viability while searching for reversible causes 1

Pharmacologic Management for Refractory VF

After failed initial defibrillation attempts, administer IV amiodarone 150 mg over 10 minutes, followed by continuous infusion at 1.0 mg/min for 6 hours, then 0.5 mg/min maintenance. 3, 5

• Amiodarone is FDA-approved for frequently recurring VF refractory to other therapy 5
• Two randomized trials demonstrated amiodarone reduces VF/VT episodes from approximately 1.7 to 0.5 per day 5
• Amiodarone shows rapid onset of antiarrhythmic activity and can be safely administered for 48-96 hours or longer if necessary 5

Administer epinephrine 1 mg IV push every 3 minutes throughout resuscitation efforts. 1, 3

• Consider high-dose epinephrine (5 mg) after 3 cycles without response 3
• For breakthrough VF episodes, give supplemental amiodarone 150 mg in 100 mL D5W over 10 minutes 5

Critical warning: Never use Class IC antiarrhythmics (flecainide, propafenone) during VF, as they paradoxically increase defibrillation threshold. 3

Advanced Airway and Vascular Access

Attempt endotracheal intubation and establish IV access without causing undue delay in CPR or defibrillation. 1, 3

• Secure advanced airway management during the 2-minute CPR intervals between shock sequences 1
• Use a central venous catheter for amiodarone concentrations >2 mg/mL 5

Systematic Search for Reversible Causes

During CPR intervals, systematically address the H's and T's: hypovolemia, hypoxia, acidosis, hypo/hyperkalemia, hypothermia, pneumothorax, tamponade, toxins, thrombosis (pulmonary and coronary). 1, 3

• Correction of electrolyte imbalances (particularly potassium and magnesium) may improve defibrillation success 1
• In the presence of acute myocardial infarction with recurrent VF, consider beta-blockers if all other therapies fail 1

Algorithm Looping for Persistent VF

For persistent VF after initial interventions, continue successive loops: 3 shocks → 2 minutes CPR → reassess rhythm → repeat. 1

• Antiarrhythmic drugs (amiodarone) should be considered after the first two sets of three shocks 1
• Continue resuscitation as long as VF persists and treatment is deemed appropriate 1
• Most patients require acute amiodarone therapy for 48-96 hours until ventricular arrhythmias stabilize 5

Safety Considerations During Defibrillation

Before each shock, give a clear "Stand clear!" command and verify no one is in contact with the patient. 1

• Remove transdermal patches to prevent electrical arcing 1
• Keep paddles/pads 12-15 cm away from implanted pacemakers 1
• Use appropriate couplants and avoid liquid/wet clothing that may cause problems 1

Prognosis and Outcome

• Primary VF occurring within the first 4 hours of MI has an incidence of 3-5% and is associated with higher in-hospital mortality 1
• Shock-resistant VF (persisting after 3 shocks) occurs in 10-25% of cardiac arrests, with 87-98% mortality 6
• Early defibrillation before drug therapy significantly improves survival (12.3% vs 3.6%) compared to delayed defibrillation 2
• The only interventions proven to improve long-term survival are basic life support and defibrillation 1