What is the recommended dosage of epinephrine (adrenaline) in cardiac arrest versus other conditions, such as anaphylaxis and severe asthma?

Epinephrine Dosing: Cardiac Arrest vs. Anaphylaxis vs. Severe Asthma

For cardiac arrest, administer 1 mg IV/IO every 3-5 minutes; for anaphylaxis, give 0.3-0.5 mg (1:1000) intramuscularly every 5-15 minutes; severe asthma does not have a specific epinephrine dosing recommendation in current guidelines and should be managed with nebulized albuterol instead. 1, 2

Cardiac Arrest Dosing

Standard-dose epinephrine (1 mg IV/IO every 3-5 minutes) is the recommended approach for adult cardiac arrest, though evidence shows it improves return of spontaneous circulation (ROSC) without clear benefit for survival to discharge or neurologically intact survival. 1

Key Dosing Parameters

• Dose: 1 mg IV/IO (1:10,000 concentration = 10 mL of 0.1 mg/mL solution) 1
• Interval: Every 3-5 minutes during ongoing resuscitation 1
• Route: Intravenous or intraosseous preferred 1

Timing Considerations

• For nonshockable rhythms (asystole/PEA): Early administration (within 1-3 minutes) is associated with improved ROSC, survival to discharge, and neurologically intact survival compared to delayed administration 1
• For shockable rhythms: Administer after initial defibrillation attempts, though optimal timing remains unclear 1

High-Dose Epinephrine: Not Recommended

• High-dose epinephrine (0.1-0.2 mg/kg) does NOT improve survival to discharge or neurological outcomes compared to standard dosing 1
• May increase ROSC but potentially worsens post-arrest outcomes 1
• Exception: Consider only for specific overdoses (beta-blocker, calcium channel blocker) 1

Anaphylaxis Dosing (Without Cardiac Arrest)

Intramuscular epinephrine into the anterolateral thigh is the first-line treatment for anaphylaxis, with IV dosing reserved only for refractory shock or when IV access is already established. 1, 2

Standard Intramuscular Dosing

• Adults and children ≥30 kg: 0.3-0.5 mg (1:1000 concentration) IM into anterolateral thigh 1, 2
• Children <30 kg: 0.01 mg/kg (1:1000 concentration) IM into anterolateral thigh 1, 2
• Repeat interval: Every 5-15 minutes as needed for persistent symptoms 1, 2
• Autoinjector doses: 0.3 mg (adult) or 0.15 mg (pediatric) 1

Intravenous Dosing for Anaphylactic Shock

When IV access is already in place and the patient has anaphylactic shock, IV epinephrine at dramatically lower doses than cardiac arrest is reasonable. 1

• IV bolus dose: 0.05-0.1 mg (50-100 mcg) using 1:10,000 concentration—this is only 5-10% of the cardiac arrest dose 1
• IV infusion: 5-15 mcg/min (0.05-0.1 mcg/kg/min), titrated to effect 1, 3
• Preparation: Dilute 1 mg (1 mL of 1:1000) in 250 mL D5W to create 4 mcg/mL concentration 1, 3
• Infusion rate: Start at 1-4 mcg/min (15-60 drops/min with microdrip), increase to maximum 10 mcg/min 1, 3

Critical Pitfall: Dosing Confusion

The most dangerous error is administering the cardiac arrest dose (1 mg IV push) to anaphylaxis patients—this causes severe systolic dysfunction, potentially lethal arrhythmias, and myocardial injury. 4

• Anaphylaxis requires 10-20 times LESS epinephrine IV than cardiac arrest 1, 4
• IM route is safer and preferred initially because it avoids this catastrophic overdose risk 1, 2
• Hospitals should stock clearly labeled, prefilled IM syringes (0.3-0.5 mg) to prevent confusion 4

Anaphylaxis-Induced Cardiac Arrest

If anaphylaxis progresses to cardiac arrest, immediately switch to standard cardiac arrest dosing (1 mg IV/IO every 3-5 minutes) along with standard ACLS measures. 1

• Standard resuscitative measures take priority 1
• Prolonged resuscitation efforts are encouraged because these patients often have healthy cardiovascular systems 1
• Asystole and pulseless electrical activity are common rhythms in anaphylaxis-induced arrest 1

Severe Asthma

Current guidelines do NOT recommend epinephrine for severe asthma exacerbations; nebulized albuterol (2.5-5 mg in 3 mL saline, repeated as necessary) is the bronchodilator of choice. 1

• Epinephrine is only mentioned for bronchospasm that is resistant to standard therapy in the context of anaphylaxis 1
• The 2020 AHA guidelines explicitly state that severe asthma management does not include routine epinephrine administration 1

Special Populations and Monitoring

Hemodynamic Monitoring Requirements

• Anaphylactic shock: Close hemodynamic monitoring is mandatory due to rapid cardiovascular changes 1
• IV epinephrine infusion: Requires invasive arterial blood pressure monitoring when possible 2
• Titration monitoring: Check blood pressure and heart rate every 5-15 minutes during initial titration 2

Beta-Blocker Complications

Patients on beta-blockers may have refractory hypotension despite epinephrine; consider glucagon 1-5 mg IV over 5 minutes followed by infusion (5-15 mcg/min). 1, 3

Pediatric Dosing Considerations

• Cardiac arrest: 0.01 mg/kg (0.1 mL/kg of 1:10,000) IV/IO every 3-5 minutes, maximum single dose 1 mg 1
• Anaphylaxis IM: 0.01 mg/kg (0.01 mL/kg of 1:1000) IM every 5-10 minutes 2
• IV infusion (pediatric "rule of 6"): 0.6 × body weight (kg) = mg diluted to 100 mL saline; then 1 mL/h delivers 0.1 mcg/kg/min 1, 3

Route-Specific Considerations

Why Intramuscular is Preferred for Anaphylaxis

• Rapid absorption: IM injection into the vastus lateralis produces faster peak plasma concentrations than subcutaneous or deltoid injection 1
• Safety profile: Avoids the risk of severe hypertension and cardiac complications from IV overdose 1, 4
• Ease of administration: Can be given through clothing in emergencies 2
• Needle length: Use at least 1/2 to 5/8 inch needle to ensure intramuscular (not subcutaneous) delivery 2

Extravasation Risk with IV Administration

• Avoid repeated injections at the same site due to vasoconstriction-induced tissue necrosis 2
• Antidote for extravasation: Infiltrate 10-15 mL saline containing 5-10 mg phentolamine into affected area within 12 hours 2
• Use large veins when possible; avoid leg veins in elderly or those with vascular disease 2

Pharmacokinetic Insights

Recent evidence suggests epinephrine elimination during cardiac arrest is prolonged (half-life ~2.6 minutes), meaning repeated standard doses every 3-5 minutes may lead to accumulating plasma levels. 5

• This prolonged elimination may explain why standard dosing improves ROSC but potentially worsens neurological outcomes 5
• Lower-dose strategies (0.5 mg instead of 1 mg) have been studied but show no significant difference in survival or neurological outcomes 6
• The optimal plasma concentration during resuscitation remains unknown 5