What are the indications and recommended dosing of adrenaline (epinephrine) for adult anaphylaxis, pediatric anaphylaxis, cardiac arrest, severe bronchospasm, and hypotension?

Adrenaline (Epinephrine) Indications and Dosing

Epinephrine is the cornerstone of anaphylaxis treatment and must be administered immediately via intramuscular injection into the anterolateral thigh at the first sign of systemic allergic reaction, with cardiac arrest management following standard ACLS protocols using 1 mg IV/IO every 3-5 minutes. 1

Adult Anaphylaxis

First-Line Intramuscular Treatment

• Administer 0.3-0.5 mg (1:1000 concentration) intramuscularly into the anterolateral thigh immediately for any patient with signs of systemic allergic reaction, especially hypotension, airway swelling, or difficulty breathing. 1
• Repeat every 5-15 minutes as needed if symptoms persist or recur—many patients require multiple doses. 1
• The intramuscular route is preferred because it produces rapid peak plasma concentrations, is safer than IV administration, and is effective even when administered by non-specialists. 1

Intravenous Epinephrine for Refractory Shock

• When IV access is already established and shock persists despite IM epinephrine, administer 0.05-0.1 mg (50-100 mcg) of 1:10,000 concentration slowly IV. 1
• This is 5-10% of the cardiac arrest dose and must never be confused with the 1 mg dose used in cardiac arrest. 1
• For ongoing refractory shock, start an IV infusion at 5-15 mcg/min and titrate to clinical response with continuous hemodynamic monitoring. 1

Critical Pitfalls to Avoid

• Never delay epinephrine administration to give antihistamines or corticosteroids—these provide no acute benefit and are not substitutes for epinephrine. 1
• Do not use the 1:1000 concentration intravenously—this can cause fatal arrhythmias and severe hypertension. 1, 2
• Close hemodynamic monitoring is mandatory because cardiovascular status can deteriorate rapidly. 1

Pediatric Anaphylaxis

Intramuscular Dosing by Weight and Age

• For children ≥30 kg: 0.3-0.5 mg (1:1000) IM into the anterolateral thigh. 1
• For children <30 kg: 0.01 mg/kg (1:1000) IM, maximum 0.3 mg. 1, 2
• Age-based dosing when weight is unknown:

  • 12 years: 0.5 mg (0.5 mL of 1:1000) 1, 3

  • 6-12 years: 0.3 mg (0.3 mL of 1:1000) 1, 3
  • ≤6 years: 0.15 mg (0.15 mL of 1:1000) 1, 3
• Repeat every 5-15 minutes as needed. 1, 3

Autoinjector Dosing

• 0.3 mg autoinjector for children ≥30 kg 1
• 0.15 mg autoinjector for children 15-30 kg 1, 3

Intravenous Dosing for Refractory Pediatric Shock

• Initial IV bolus: 1 mcg/kg (0.01 mL/kg of 1:10,000), titrated to response. 3, 2
• Many pediatric patients respond to as little as 1 mcg/kg IV. 3
• For infusion: 0.05-0.1 mcg/kg/min, titrated to effect. 2

Cardiac Arrest

Standard ACLS Dosing

• Administer 1 mg IV/IO (1:10,000 concentration) every 3-5 minutes during ongoing resuscitation. 2
• This applies to all cardiac arrest rhythms (shockable and non-shockable). 2
• Early administration (within 1-3 minutes) improves return of spontaneous circulation (ROSC), particularly for non-shockable rhythms. 2

Cardiac Arrest from Anaphylaxis

• Standard resuscitative measures and immediate epinephrine administration take priority. 1
• For refractory anaphylactic cardiac arrest, consider high-dose escalation: 1-3 mg IV over 3 minutes, then 3-5 mg over 3 minutes, followed by 4-10 mcg/min infusion. 2
• Antihistamines, inhaled beta-agonists, and corticosteroids have no proven benefit during anaphylaxis-induced cardiac arrest. 1

Pediatric 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. 2

Important Evidence Caveat

• High-dose epinephrine (0.1-0.2 mg/kg) does not improve survival to discharge or neurological outcomes compared to standard dosing and may worsen post-arrest outcomes. 2

Severe Bronchospasm

Epinephrine is NOT Recommended for Asthma

• For severe asthma exacerbations, use nebulized albuterol 2.5-5 mg in 3 mL saline, repeated as necessary—not epinephrine. 2
• Epinephrine is reserved for anaphylaxis with bronchospasm, not isolated asthma. 2

Persistent Bronchospasm in Anaphylaxis

• If bronchospasm persists despite epinephrine, administer nebulized albuterol 2.5-5 mg in 3 mL saline. 3
• Consider IV salbutamol infusion, aminophylline, or magnesium sulfate for refractory cases. 1, 3

Hypotension Management

Fluid Resuscitation is Essential

• Administer 0.9% saline or lactated Ringer's solution rapidly via large-bore IV—large volumes (500-1000 mL for adults, 20 mL/kg for children) may be required. 1, 3
• Massive capillary leak in anaphylaxis necessitates aggressive fluid resuscitation. 3

Refractory Hypotension Despite Epinephrine

• For patients on beta-blockers with refractory hypotension, administer glucagon 1-5 mg IV over 5 minutes (20-30 mcg/kg for children, maximum 1 mg), followed by infusion at 5-15 mcg/min. 3, 2
• Beta-blockers blunt the response to epinephrine, making glucagon a critical rescue agent. 3, 2

Airway Management Considerations

• Immediately refer to a provider with advanced airway expertise because oropharyngeal or laryngeal edema can develop rapidly. 1
• Prepare for emergency cricothyrotomy or tracheostomy if airway obstruction develops, as conventional intubation may be impossible. 1, 3
• Administer 100% oxygen and secure the airway promptly. 3

Adjunctive Medications (Second-Line Only)

These Provide No Acute Benefit

• H1-antihistamine (diphenhydramine 25-50 mg IV/IM for adults, 1-2 mg/kg for children) may be given after epinephrine but never delays it. 3, 2
• H2-antihistamine (ranitidine 50 mg IV for adults, 1 mg/kg for children) in combination with H1 is superior to H1 alone but remains second-line. 3, 2
• Corticosteroids (methylprednisolone 1-2 mg/kg IV or hydrocortisone 200 mg IV for adults; age-based dosing for children) may prevent biphasic reactions but provide no acute benefit. 1, 3, 2

Pediatric Corticosteroid Dosing

• 12 years: Hydrocortisone 200 mg IV/IM 3

• 6-12 years: Hydrocortisone 100 mg IV/IM 3
• 6 months-6 years: Hydrocortisone 50 mg IV/IM 3
• <6 months: Hydrocortisone 25 mg IV/IM 3

Observation and Discharge

• Observe all patients for at least 4-6 hours after symptom resolution, with longer observation for severe reactions, persistent airway symptoms, or multiple epinephrine doses. 3, 2
• Biphasic reactions occur in 7-18% of cases and are unpredictable. 3
• Prescribe two epinephrine autoinjectors with hands-on training, a 2-3 day course of prednisone (1 mg/kg daily, maximum 60-80 mg), H1-antihistamine, and H2-antihistamine. 3
• Arrange follow-up with an allergist within 1-2 weeks. 3