What medications are used to treat a patient in cardiac arrest?

Medications Used in Cardiac Arrest

Epinephrine 1 mg IV/IO every 3-5 minutes is the cornerstone vasopressor for all cardiac arrest rhythms, administered after initial CPR and defibrillation attempts in shockable rhythms or as soon as feasible in non-shockable rhythms, while amiodarone 300 mg IV/IO (followed by 150 mg if needed) or lidocaine 1-1.5 mg/kg IV/IO serve as antiarrhythmic options for refractory ventricular fibrillation/pulseless ventricular tachycardia. 1, 2

Vasopressor Therapy

Epinephrine (Primary Agent)

• Standard dosing: 1 mg IV/IO every 3-5 minutes for all cardiac arrest rhythms 1, 2
• Timing for shockable rhythms (VF/pVT): Administer after the third unsuccessful defibrillation attempt, prioritizing CPR and defibrillation initially 1
• Timing for non-shockable rhythms (PEA/asystole): Administer as soon as feasible, with earlier administration associated with improved ROSC rates 1
• Route: IV access is preferred first; if unsuccessful or not feasible, use IO access 2, 3

Important caveat: While epinephrine improves ROSC and survival to hospital admission, it has not been definitively shown to improve long-term survival with favorable neurological outcomes 1, 4, 5. However, it remains the standard of care based on short-term benefits 1, 2.

Dosing considerations:

• Standard 1 mg dosing is recommended; high-dose epinephrine (>1 mg) has shown higher ROSC rates but no improvement in survival to discharge or neurological outcomes and may be harmful 1, 5, 6
• Operationally, administering epinephrine every second cycle of CPR after the initial dose may be reasonable 1

Alternative Vasopressor Combinations

• Vasopressin plus methylprednisolone: A trial showed that 20 IU vasopressin plus 40 mg methylprednisolone after the first dose of epinephrine increased ROSC by 9.6% in in-hospital cardiac arrest, but did not improve 30-day survival or neurological outcomes 1
• Vasopressin alone: No difference in outcomes compared to epinephrine alone 1

Antiarrhythmic Medications (For Refractory VF/pVT Only)

Amiodarone (First-Line Antiarrhythmic)

• First dose: 300 mg IV/IO bolus after the third unsuccessful defibrillation attempt 1, 2, 7
• Second dose: 150 mg IV/IO bolus for persistent or recurrent VF/pVT after additional shock(s) 2, 7
• Evidence: Improved survival to hospital admission in bystander-witnessed arrests, but did not improve overall survival to discharge or favorable neurological outcomes 1

Critical pitfall: Do not administer both doses back-to-back; reserve the second dose for ongoing refractory rhythm 2

Lidocaine (Alternative Antiarrhythmic)

• First dose: 1-1.5 mg/kg IV/IO (typically 75-100 mg) 1, 2, 7
• Second dose: 0.5-0.75 mg/kg IV/IO, may repeat every 5-10 minutes up to 3 mg/kg total 2, 7
• Use when: Amiodarone is unavailable or as an alternative 1, 2, 7
• Evidence: Similar to amiodarone, improved survival to hospital admission in bystander-witnessed arrests but no improvement in long-term outcomes 1

FDA precautions: Use with caution in elderly patients, those with hepatic disease, severe shock, or heart block; debilitated patients require reduced doses 8

Other Antiarrhythmics

• Procainamide: Not appropriate during cardiac arrest due to slow infusion rate, lack of survival benefit, and high proarrhythmia risk, especially in elderly patients 7
• Bretylium: Not recommended due to biphasic hemodynamic profile causing initial hypertension followed by hypotension 1, 7
• Magnesium: No evidence of improved ROSC, survival, or neurological outcomes regardless of presenting rhythm 1

Medications NOT Routinely Recommended

Atropine

• No longer recommended for routine use in cardiac arrest (asystole/PEA) 1
• May be used for symptomatic bradycardia in the periarrest setting, but not during pulseless arrest 1

Sodium Bicarbonate

• Not routinely recommended: Evidence suggests it may worsen survival and neurological recovery in undifferentiated cardiac arrest 1
• Special circumstances only: Hyperkalemia, tricyclic antidepressant overdose, or other specific toxicological emergencies 1

Calcium

• Not routinely recommended for undifferentiated cardiac arrest 1, 4
• Special circumstances only: Hyperkalemia, hypocalcemia, calcium channel blocker overdose, or hypermagnesemia 1

Practical Algorithm for Medication Administration

For Shockable Rhythms (VF/pVT):

1. Immediate defibrillation with high-quality CPR 2, 3
2. After 3rd unsuccessful shock: Epinephrine 1 mg IV/IO 1, 2
3. Continue epinephrine 1 mg IV/IO every 3-5 minutes 1, 2
4. After 3rd shock (or with epinephrine): Consider amiodarone 300 mg IV/IO OR lidocaine 1-1.5 mg/kg IV/IO 1, 2, 7
5. If rhythm persists: Second dose of amiodarone 150 mg IV/IO OR lidocaine 0.5-0.75 mg/kg IV/IO 2, 7

For Non-Shockable Rhythms (PEA/Asystole):

1. High-quality CPR immediately 2, 3
2. Epinephrine 1 mg IV/IO as soon as feasible (earlier is better for ROSC) 1, 2
3. Continue epinephrine 1 mg IV/IO every 3-5 minutes 1, 2
4. Focus on reversible causes: Hypovolemia, hypoxia, hydrogen ion (acidosis), hypo-/hyperkalemia, hypothermia, tension pneumothorax, tamponade, toxins, thrombosis (pulmonary/coronary) 2, 3

Critical Considerations and Common Pitfalls

• Do not delay CPR for medication administration: High-quality chest compressions with minimal interruptions are more important than any medication 1, 2, 3
• No antiarrhythmic has proven long-term benefit: Despite widespread use, no antiarrhythmic drug definitively increases survival to discharge or improves neurological outcomes 1, 3, 4
• Avoid high-dose epinephrine: Doses >1 mg do not improve outcomes and may be harmful 1, 5, 6
• Monitor for ROSC: Abrupt sustained increase in PETCO₂ (typically ≥40 mm Hg) or return of palpable pulse indicates ROSC 2, 3
• Antiarrhythmics are for refractory VF/pVT only: Do not use amiodarone or lidocaine for non-shockable rhythms 1, 2, 3
• Establish vascular access early: IV preferred, but do not delay epinephrine if IO access is faster 2, 3