• A 23-year-old woman with past medical history of multiple allergies leading to facial swelling presents with marked difficulty breathing, abdominal pain, and swelling of the face and neck. On physical exam, her extremities are also noted to be markedly swollen (picture). She is immediately sedated for intubation to maintain patency of airway. Chart review reveals newly-started ACE-inhibitor. She is given epinephrine, fluids, and fresh frozen plasma.

  • Disorder of complement, causing angioedema
  • Genetics
    • autosomal dominant
  • Pathogenesis
    • C1 esterase inhibitor deficiency
      • C1 esterase inhibitor inhibits kallikrein-kinin pathway
        • remember kallikrein activates bradykinin
        • bradykinin
          • ↑ vasodilation
          • ↑ permeability
          • ↑ pain
    • ACE-inhibitors are contraindicated
      • ACE inactivates bradykinin
      • ACE-inhibitors allows ongoing bradykinin, causing angioedema
  • Epidemiology
    • attacks begin during childhood
  • Risk factors
    • family history of angioedema
    • family history of those contraindicated with ACE-inhibitors
    • autoimmune conditions
  • Symptoms/physical exam
    • recurrent episodes of angioedema without urticaria
      • as opposed to anaphylaxis, which typically has urticarial
      • angioedema of the face, oropharynx, extremities, or abdomen
      • angioedema of GI tract
        • severe abdominal pain
        • GI upset
      • worst at 24 hours
      • resolves over 48-72 hours
    • often preceded by prodrome
      • fatigue
      • flu-like symptoms
    • not responsive to epinephrine (epi-pen) or antihistamines
  • Best initial test
    • ↓ C4 and C2 levels
    • if C4 are normal, C1 inhibitor deficiency is unlikely
  • To confirm diagnosis if ↓ C4
    • ↓ C1 inhibitor antigenic levels
    • ↓ C1 inhibitor functional levels
Differential Diagnosis
  • Anaphylaxis
  • Allergic angioedema
  • Facial cellulitis
  • SVC syndrome
  • Anaphylaxis presents very similarly to angioedema and often cannot be differentiated immediately in an emergency room setting
    • therefore, patients are often initially treated with medications for anaphylaxis given urgent, life-threatening nature of anaphylaxis
      • epinephrine
      • fluid replacement
      • anti-histamines
  • Assess airwa, even after administering treatment
    • intubate if necessary
  • As soon as possible, especially if epinephrine and anti-histamines are not effective, administer medications for hereditary angioedema
    • plasma-derived C1 inhibitor
    • recombinant human C1 inhibitor
    • fresh frozen plasma if above are not available
Prognosis, Prevention, and Complications
  • Prognosis
    • mortaliy >30% in those with laryngeal angioedema
    • angioedema is unpredictable
  • Complications
    • small bowel obstruction
    • compartment syndrome
    • death by asphyxiation

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