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Anaphylaxis 

 

 

Signs

 

  • Rash/hives

  • Angioedema

  • Hypotension

  • Tachycardia

  • Hypoxemia

  • Bronchospasm/wheezing

  • ↑ peak inspiratory pressure

 

 

Management 

 

  • Stop offending agent 

  • Inform surgeon, call for help 

  • Discontinue or ↓ all anesthetic agents 

  • Airway:

    • 100% O2 

    • Secure airway 

  • Administer epinephrine IV in escalating doses:

    • Start at 10-100 mcg & ↑ as necessary until clinical improvement 

    • Consider early epinephrine infusion (start at 2-20mcg/min)

  • Aggressive fluid resuscitation (may require several litres) 

  • Bronchospasm: salbutamol PRN 

  • Give secondary medications:

    • H1 antagonist: diphenhydramine 25-50mg IV 

    • H2 antagonist: ranitidine 50mg IV  

    • Methylprednisolone 1-2mg/kg IV per day OR dexamethasone 20mg IV 

  • Start invasive lines: arterial line, central line 

  • Refractory hypotension despite epinephrine:

    • Vasopressin 1-40 unit bolus, 0.01-0.04 units/min infusion

    • Glucagon 1-2 mg over 5 min IV then 5-15 mcg/min IV infusion (especially for patients taking beta blockers; inotropic & chronotropic effects not mediated through beta receptors)

    • Methylene blue 1-2mg/kg IV (inhibits nitric oxide synthase & guanylate cyclase)

    • Consider bicarbonate (0.5-1 mEq/kg) with acidosis

    • Consider transesophageal echocardiography (TEE) & entertain other differential diagnosis 

  • Post-event care:

    • Laboratory tests to support diagnosis:

      • Serum tryptase levels 15 minutes and 3 hours after onset of symptoms

      • Serum histamine levels peak 5 - 15 minutes after onset of symptoms; return to baseline at 60 minutes

    • Discharge to ICU intubated & ventilated 

    • Due to biphasic nature, monitor at least 24 hours

    • Consult allergist 

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