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Anaphylaxis

DEFINTION

  • Etiology: An acute multisystem response caused by a severe reaction to any antigen, such as a drug, vaccine, food, toxin, plant, or venom

  • Clinical Presentation:

    • Systemic vasodilation:

      • Hypotension

      • Tachycardia

    • Increased capillary permeability:

      • Angioedema – may lead to partial or complete airway obstruction

      • Worsens hypotension

    • Pulmonary vasoconstriction:

      • Decreased pulmonary blood flow

      • Increased right ventricular afterload

      • Decreased left ventricular preload

    • Bronchoconstriction/bronchospasm

      • Respiratory distress +/− stridor, wheezing, or both

    • Histamine release:

      • Urticaria

      • Nausea and vomiting

MANAGEMENT

REMOVE/DISCONTINUE OFFENDING AGENT

  • Example: Discontinue medication infusion

INITIATE SUPPORTIVE CARE

  • ABCs:

    • Administer 100% oxygen

    • Maintain airway:

      • Positioning: place patient supine

      • Stabilization (i.e., bag-mask ventilation and/or endotracheal intubation [ETT] if necessary)

    • Suction as needed

    • Pulse oximetry

    • Obtain intravenous/intraosseous (IV/IO) access

    • EKG monitoring

INITIATE MEDICATION ADMINISTRATION

  • Epinephrine:

    • Intramuscular (IM):

      • 0.01 mg/kg/dose = 0.01 mL/kg/dose q10–15min prn

      • Max single dose 0.3 mg

      • 1 mg/mL; 1:1000 concentration

    • IM autoinjector:

      • Weight 10 to 30 kg = 0.15 mg

      • Weight ≥30 kg = 0.3 mg

    • IV/IO bolus dose:

      • 0.01 mg/kg/dose = 0.1 mL/kg/dose IV/IO q3–5min prn

      • Max single dose 1 mg

      • 0.1 mg/mL; 1:10,000 concentration

    • IV/IO continuous infusion:

      • 0.1 to 1 mcg/kg/min IV/IO infusion

      • If hypotension persists despite fluids and IM injection

  • Albuterol:

    • Nebulizer:

      • Weight <20 kg: 2.5 mg/dose via inhalation q20min prn

      • Weight >20 kg: 5 mg/dose via inhalation q20min prn

    • Continuous nebulizer:

      • 0.5 mg/kg per hour via continuous inhalation

      • Max dose 20 mg/hr

      • Indicated for severe bronchospasm

    • Metered dose inhaler (MDI: 90 mcg/puff):

      • 4 to 8 puffs via inhalation q20min prn with spacer (or ETT if intubated)

  • Corticosteroids:

    • Methylprednisolone (reduces late-phase reaction):

      • Load 2 mg/kg IV/IM/IO (max 60 mg); use only acetate salt IM

      • Maintenance: 0.5 mg/kg IV/IO q6hr or 1 mg/kg q12hr (max 120 mg/day)

  • Antihistamine:

    • H1-receptor antagonist: diphenhydramine

      • 1 to 2 mg/kg/dose IM/IV/IO over 5 min q4–6hr

      • Maximum single dose 50 mg

    • H2-receptor antagonist: ranitidine or famotidine

      • Ranitidine: 1 mg/kg/dose IV

        • Maximum single dose of 50 mg

      • Famotidine: 0.25 mg/kg/dose IV

        • Maximum daily dose of 40 mg

    • The combination of both H1 and H2 blocker may be more effective than giving either alone.

  • Hypotension:

    • Isotonic crystalloid infusion:

      • Rapid infusion 20 mL/kg – repeat as needed

      • Normal saline or lactated Ringer's

    • Epinephrine infusion (see earlier):

      • Initiate for hypotension that is unresponsive to fluid and IM epinephrine administration

      • Titrate to achieve normal blood pressure for the patient's age

SUGGESTED READINGS

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American Heart Association. Pediatric Advanced Life Support Provider Manual. Dallas, TX: First American Heart Association Printing; 2016.
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American Heart Association. Pediatric Advanced Life Support Reference Card. Dallas, TX: American Heart Association; 2016.
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American Heart Association. 2015 Handbook of Emergency Cardiovascular Care for Healthcare Providers. Dallas, TX: First American Heart Association Printing; 2015.

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