What is the immediate treatment for a pediatric patient experiencing anaphylaxis?

Immediate Treatment for Pediatric Anaphylaxis

Administer intramuscular epinephrine 0.01 mg/kg (maximum 0.3 mg in prepubertal children, 0.5 mg in adolescents) into the mid-outer thigh (vastus lateralis) immediately upon recognition of anaphylaxis. 1, 2

First-Line Treatment: Epinephrine

Epinephrine is the only first-line medication for anaphylaxis—there are no substitutes. 2, 3

Route and Administration

• Intramuscular injection into the lateral thigh (vastus lateralis) is the preferred route, achieving peak plasma concentrations in 8 ± 2 minutes compared to 34 ± 14 minutes with subcutaneous deltoid injection 1, 4
• Use epinephrine 1:1000 solution (1 mg/mL) at 0.01 mg/kg dose 1, 2
• Repeat every 5-15 minutes as needed if symptoms persist or recur 2, 3

Autoinjector Dosing

• 0.15 mg autoinjector for children 10-25 kg 2, 5
• 0.30 mg autoinjector for children ≥25 kg 2, 5
• For infants <7.5 kg, the 0.15 mg autoinjector is still preferable to ampule/syringe/needle methods due to significant dosing errors and delays with manual preparation 2, 6

Critical Timing

Delayed epinephrine administration is directly associated with anaphylaxis fatalities—inject at the earliest sign of anaphylaxis 2, 3, 6

Supportive Measures

Positioning and Monitoring

• Position patient supine with legs elevated (unless respiratory distress or vomiting present, then position of comfort) 2, 3
• Call for emergency assistance (911/EMS) immediately 3
• Establish IV access and provide supplemental oxygen 2, 5
• Continuously monitor vital signs, heart rate, and blood pressure 2

Fluid Resuscitation

• Administer crystalloid fluid bolus: 500 mL for moderate reactions (Grade II), 1 L for severe reactions (Grade III) 2, 5
• Escalate to 20-30 mL/kg for refractory cases, repeating boluses as needed based on clinical response 2, 5

Management of Refractory Anaphylaxis

Additional Epinephrine Dosing

• If inadequate response after 10 minutes, double the epinephrine bolus dose 2
• Consider IV epinephrine only for cardiac arrest or profound hypotension unresponsive to multiple IM doses: 20 μg for Grade II, 50-100 μg for Grade III, 1 mg for Grade IV (cardiac arrest) 2, 5
• Start epinephrine infusion (0.05-0.1 μg/kg/min) when more than three boluses have been administered 2, 5

Alternative Vasopressors

• For persistent hypotension despite epinephrine, add norepinephrine infusion (0.05-0.5 μg/kg/min) 2, 5
• Consider vasopressin 1-2 IU bolus with or without infusion (2 units/h) for refractory hypotension 2
• Dopamine 2-20 μg/kg/min may be used, titrated to maintain systolic BP >90 mmHg 2

Special Populations

For patients on beta-blockers with refractory symptoms, administer IV glucagon 1-2 mg (20-30 μg/kg in children, maximum 1 mg) 2, 5

Adjunctive Therapies (NOT Substitutes for Epinephrine)

Antihistamines

• H1 antihistamines (diphenhydramine 25-50 mg IV or 1-2 mg/kg PO, maximum 50 mg) are adjunctive ONLY for cutaneous symptoms—never administer before or instead of epinephrine 2, 5, 3
• H1 antihistamines have slow onset (≥1 hour) and do not relieve respiratory symptoms or shock 2
• H2 antihistamines (ranitidine 50 mg IV in adults) may be added after adequate epinephrine and fluid resuscitation 5

Bronchodilators

• Inhaled albuterol may provide adjunctive therapy for wheezing in patients with preexisting asthma but does not replace epinephrine 2, 3
• For severe asthma exacerbation component: albuterol with simultaneous epinephrine and corticosteroids 1

Corticosteroids

• Consider systemic glucocorticosteroids (dexamethasone 1-2 mg/kg IM) for patients with history of idiopathic anaphylaxis, asthma, or severe/prolonged reactions to potentially prevent biphasic reactions 2, 3
• Corticosteroids do not treat acute anaphylaxis but may help prevent late-phase reactions 3

Post-Anaphylaxis Management

Observation Period

• Observe in a monitored area for minimum 6 hours or until stable and symptoms are regressing 2, 5, 3
• High-risk patients (Grade III-IV reactions, required >1 dose epinephrine, severe reactions) may require extended observation or ICU admission 2, 5
• Monitor for biphasic reactions—symptoms may recur hours later even after successful initial treatment 5, 3

Diagnostic Testing

• Obtain mast cell tryptase samples: first at 1 hour after reaction onset, second at 2-4 hours, and baseline at least 24 hours post-reaction 2, 5

Discharge Requirements

• Prescribe two epinephrine autoinjectors before discharge (0.15 mg for 10-25 kg; 0.3 mg for ≥25 kg) 2, 5
• Provide written personalized anaphylaxis emergency action plan including common symptoms/signs, clear instructions, and list of known triggers 2, 5, 3
• Train patient/family on autoinjector use and anaphylaxis recognition 2, 5
• Arrange allergist referral for trigger identification and consideration of allergen immunotherapy (e.g., venom immunotherapy) 2, 3
• Establish plan for monitoring autoinjector expiration dates 5

Critical Pitfalls to Avoid

• Never substitute antihistamines or corticosteroids for epinephrine as first-line treatment—this is associated with fatalities 2, 3, 7
• Do not administer IV epinephrine in non-arrest situations without appropriate monitoring and continuous hemodynamic monitoring 1, 2
• Avoid premature discharge without adequate observation for biphasic reactions 2
• Patients with preexisting severe uncontrolled asthma are at higher risk for fatal anaphylaxis 2, 5
• Adolescents have particularly high risk for fatal anaphylaxis 2
• Do not prescribe ampule/syringe/needle for home use due to 40-fold variation in dosing accuracy and significant delays 2
• There are no absolute contraindications to epinephrine use in anaphylaxis, even in high-risk patients (elderly with comorbidities, complex congenital heart disease, pulmonary hypertension) 5