What is the proper administration and treatment protocol for anaphylaxis using an EpiPen (epinephrine) in a patient weighing 25 kg or more?

EpiPen (Epinephrine 0.3mg) Treatment Protocol for Anaphylaxis

Immediate Administration

Inject 0.3 mg epinephrine intramuscularly into the anterolateral thigh (vastus lateralis) immediately upon recognition of anaphylaxis, and repeat every 5 minutes as needed until symptoms resolve. 1, 2

Proper Injection Technique

• Insert the autoinjector at a 90-degree angle perpendicular to the skin in the mid-outer aspect of the thigh to ensure intramuscular delivery rather than subcutaneous 3
• The injection can be administered through clothing if necessary—do not delay for clothing removal 3
• The lateral thigh site achieves peak plasma concentrations in 8±2 minutes compared to 34±14 minutes with subcutaneous deltoid injection 1, 3

Dosing Parameters

• For patients ≥25 kg (55 lbs): Use 0.3 mg EpiPen (adult dose) 3, 2
• For patients 10-25 kg: Use 0.15 mg EpiPen Jr 3
• The standard dose is 0.01 mg/kg, with a maximum single dose of 0.5 mg for adults 1, 2

Repeat Dosing Protocol

There is no maximum number of epinephrine doses—repeat every 5 minutes as clinically needed until symptoms resolve. 1

• Approximately 10-28% of patients require a second dose, and some require more 1
• The 5-minute interval can be liberalized to permit more frequent injections if the clinical situation demands it 4, 1
• Continue dosing based on clinical response rather than an arbitrary maximum number 1

Common Pitfall to Avoid

Stopping at one dose prematurely is a critical error—if symptoms persist or progress after the first injection, continue dosing every 5 minutes. 1 Delayed or inadequate epinephrine administration has been directly associated with anaphylaxis fatalities. 5, 6, 7

Concurrent Emergency Management

Call 911 or activate the resuscitation team immediately—do not wait to see if epinephrine works. 1

• Position the patient supine with legs elevated 1
• Never allow the patient to stand or walk, as upright positioning increases mortality risk 1
• Administer oxygen at 6-8 L/min 4
• Establish IV access and prepare for fluid resuscitation 4

Fluid Resuscitation for Hypotension

• Administer normal saline bolus of 1000-2000 mL for adults (5-10 mL/kg in first 5 minutes) 4, 1
• Children may require up to 30 mL/kg in the first hour 4
• Large volumes of crystalloid may be necessary—some patients require 1-2 L rapidly 4

Escalation for Severe/Refractory Cases

If the patient fails to respond to multiple IM doses (typically 2-3 injections), transition to IV epinephrine infusion. 1, 8

IV Epinephrine Preparation and Dosing

• Preparation: Add 1 mg (1 mL) of 1:1000 epinephrine to 250 mL D5W to yield 4.0 mcg/mL concentration 4, 8
• Starting infusion rate: 1-4 mcg/min (15-60 drops/min with microdrop apparatus) 4, 8
• Titrate up to maximum of 10 mcg/min based on clinical response 4, 1, 8
• Requires continuous hemodynamic monitoring—IV epinephrine carries significant risk of arrhythmias and dosing errors 1, 8

Alternative IV Preparation Method

• Add 1 mg (1 mL) of 1:1000 epinephrine to 100 mL saline (1:100,000 solution) 4, 8
• Infuse at 30-100 mL/hr (5-15 mcg/min), titrated based on response 4, 8

Adjunctive Therapies (Secondary to Epinephrine)

These are adjuncts only—never delay epinephrine to give antihistamines or corticosteroids first. 3

• H1 antihistamine: Diphenhydramine 25-50 mg parenterally 1
• H2 antihistamine: Ranitidine 50 mg IV over 5 minutes or famotidine 1
• Corticosteroids: Hydrocortisone for severe cases (does not affect acute phase but may prevent biphasic reactions) 1

Post-Treatment Management

Transport all patients to the emergency department via EMS for observation, even if symptoms completely resolve after epinephrine. 1

• Observation period required: Biphasic reactions can occur up to 72 hours later (mean 11 hours) 3
• Prescribe two 0.3 mg epinephrine autoinjectors for home use with proper instruction 1, 2
• Refer to allergist-immunologist for follow-up and identification of trigger 1

Critical Safety Points

There is no absolute contraindication to epinephrine use in anaphylaxis—even in elderly patients or those with cardiac disease, the risk of death from untreated anaphylaxis far exceeds the risk of epinephrine-related adverse effects. 4, 1, 3

Common Adverse Effects (Accept These as Necessary)

• Pallor, tremor, anxiety, palpitations, headache, and nausea are expected therapeutic effects that cannot be dissociated from epinephrine's life-saving actions 3, 2
• These side effects are not reasons to withhold or delay epinephrine 4

Critical Errors to Avoid

• Delaying epinephrine while giving antihistamines first—fatalities are associated with delayed epinephrine, not with giving multiple doses 1, 7
• Using subcutaneous route instead of intramuscular—this delays absorption significantly 3, 9
• Injecting into the deltoid instead of the thigh—the thigh provides superior and more consistent absorption 3
• Confusing concentrations—always use 1:1000 (1 mg/mL) for IM injection; 1:10,000 is reserved for IV use only 1