What is the role of epinephrine (adrenaline) in cardiopulmonary resuscitation (CPR)?

Role of Epinephrine in Cardiopulmonary Resuscitation (CPR)

Epinephrine is strongly recommended during CPR to increase return of spontaneous circulation (ROSC) and survival, with administration timing varying based on cardiac rhythm: immediate for non-shockable rhythms and after initial defibrillation attempts for shockable rhythms. 1

Mechanism of Action and Benefits

• Epinephrine increases coronary perfusion pressure through alpha-adrenergic vasoconstriction, which improves blood flow to the heart during CPR 2
• The standard adult dose is 1 mg IV/IO every 3-5 minutes during CPR 3
• Epinephrine significantly increases rates of ROSC across all cardiac arrest rhythms (high certainty evidence) 1
• For patients with non-shockable rhythms (PEA/asystole), epinephrine improves survival to discharge (moderate certainty evidence; RR, 2.56; 95% CI, 1.37–4.80) 1

Timing of Administration

• For non-shockable rhythms (PEA/asystole), administer epinephrine as soon as feasible after establishing vascular access (strong recommendation) 1
• For shockable rhythms (VF/pVT), administer epinephrine after initial defibrillation attempts have been unsuccessful (weak recommendation) 1
• Earlier administration of epinephrine is associated with improved outcomes compared to delayed administration, particularly for non-shockable rhythms 1

Neurological Outcomes and Controversies

• While epinephrine increases ROSC and short-term survival, its effect on favorable neurological outcomes remains uncertain 1
• In patients with non-shockable rhythms, epinephrine approaches statistical significance for improved neurological outcomes at 3 months (RR, 3.03; 95% CI, 0.98–9.38) 1
• For shockable rhythms, studies have not demonstrated a clear benefit in neurological outcomes with epinephrine 1
• The potential increase in survivors with unfavorable neurological outcomes has raised concerns, though the 2019 guidelines state that data at 3 months do not support this assertion 1

Alternative Vasopressors

• Vasopressin is not recommended as a substitute for epinephrine (weak recommendation, very low certainty evidence) 1
• The combination of vasopressin plus epinephrine offers no benefit over epinephrine alone 1
• High-dose epinephrine (>1 mg) increases ROSC but does not improve survival to discharge or neurological outcomes 1, 3

Special Considerations

• Epinephrine may cause tachyarrhythmias, myocardial ischemia, and pulmonary edema, particularly in patients with coronary artery disease 4
• Monitor for extravasation during IV administration, which can cause tissue necrosis; if extravasation occurs, infiltrate the area with 5-10 mg of phentolamine in 10-15 mL saline 4
• Epinephrine contains sodium metabisulfite, which may cause allergic reactions, but this should not preclude its use in life-threatening situations 4

Common Pitfalls

• Delaying epinephrine administration in non-shockable rhythms can worsen outcomes 1, 5
• Focusing solely on ROSC without considering long-term neurological outcomes 6, 7
• Using high-dose epinephrine routinely, which increases ROSC but not survival to discharge 1, 3
• Failing to recognize that the effects of epinephrine may vary with the duration of cardiac arrest - longer arrests show more post-ROSC myocardial depression with epinephrine 8

The evidence clearly supports epinephrine's role in increasing ROSC and short-term survival during CPR, with the strongest benefit seen in non-shockable rhythms. While questions remain about its impact on long-term neurological outcomes, current guidelines strongly recommend its use as a fundamental component of advanced cardiac life support.