Angioedema

Bradykinin-Mediated

Pt with h/o HTN, HFpEF presents with acute onset angioedema. Reports recent increase in ACE inhibitor dose, abdominal pain. Family history of angioedema. Hypotension, rigid abdomen, edematous swelling involving face/tongue/hands/buttocks/genitals on exam. No urticaria noted.

  • Obtain CBC, CMP, U/A, ESR, C4 protein level

  • Treatment

    • Stop ACE inhibitor

    • Administer 1L NS bolus and re-evaluate BP

    • Administer one of the following and repeat q3 hours PRN

      • 0.5 mL racemic epinephrine 2.25% solution

      • 0.3 mg epinephrine IM

    • Administer 1u fresh-frozen plasma

    • Consider methylprednisolone (Solu Medrol) 40 mg IV q6 hours, diphenhydramine (Benadryl) 25 mg IV q6 hours

    • Concern for hereditary angioedema: C1-inhibitor concentrate if available

  • Patient advised to follow-up with allergy specialist

Notes

  • ACE inhibitors produce bradykinin-mediated angioedema

  • No mast cell degranulation/histamine release = no urticaria

  • GI tract swelling may mimic a surgical abdomen on exam

  • If concerned about an allergic component, Solumedrol and Benadryl can be started

Histamine-Mediated Angioedema

Pt with h/o multiple allergies presents with acute onset swelling and hives. Pt consumed peanut/lobster/tomato omlet and self-administered PCN 1 hour prior to symptom onset. Stung by wasp en route to hospital. Reports previous episodes of similar symptoms and recent increase in nocturnal pruritus. Medications include codeine, muscle relaxants, vancomycin, aspirin, NSAIDs. Swelling of face/tongue/hands/buttocks/genitals, multiple round and irregularly shaped pruritic wheals (urticaria) on exam.

  • Obtain CBC, CMP, U/A, ESR

  • Discontinue medications that may be contributing to condition

  • Concern for airway compromise/distributive shock

    • Administer IM epinephrine

    • Consult ENT

    • Prepare for intubation

  • Chronic urticaria

    • Start loratadine (Claritin) 10mg daily

    • Diphenhydramine (Benadryl) 25 mg at bedtime for nocturnal pruritus

    • Add ranitidine (Zyrtec) 150 mg daily for additional symptom control

    • Prednisone 40 mg daily x5 days for acute, severe symptoms

    • Epinephrine auto injector (EpiPen) 0.3mg for emergencies

    • Refer to allergy-immunology specialist

    • Pt counseled about sedating effects of first generation H1 blockers (diphenhydramine)

    • Pt instructed in use of EpiPen

Notes

  • Urticaria = histamine release = treatment with antihistamine agents

  • Common causes of histamine release include drugs (PCN, cephalosporin), hymenoptera insect (wasp, ant) venom, foods, latex, environmental allergies

  • Histamine-mediated urticaria is treated with H1 blockers (loratadine, diphenhydramine) and H2 blockers (ranitidine)