Angioedema Emergency Management

Algorithm Steps

1. ▶

   Start

   Angioedema Presenting to ED

   Swelling of face, lips, tongue, uvula, or larynx

   1. ⚠

      Warning

      Immediate Airway Assessment

      Is airway compromised?

      • Stridor, dyspnea, drooling, voice changes
      • Prepare for difficult airway
      • Have cricothyrotomy equipment ready
      • Avoid paralysis without backup plan
      1. ⚠

         Warning

         Airway Compromised

         Urgent airway intervention needed

         • Call anesthesia/ENT for backup
         • Awake fiberoptic intubation preferred
         • Avoid paralysis if possible
         • Double setup: intubation + surgical airway ready
         • Consider nasopharyngeal scope to assess
         • Heliox may temporize
         1. ◆

            Decision

            Differentiate Mechanism

            Histamine-mediated vs Bradykinin-mediated

            • HISTAMINE: Fast onset (min-hrs), urticaria/pruritus, responds to epinephrine
            • BRADYKININ: Slow onset (24-36h), NO urticaria, does NOT respond to epinephrine
            • Clues for bradykinin: ACE-I use, HAE history, family history, recurrent episodes without urticaria
            1. ●

               Action

               Histamine-Mediated (Allergic)

               Treat as anaphylaxis

               • EPINEPHRINE IM: 0.3-0.5 mg (0.01 mg/kg in children)
               • Repeat q5-15min if needed
               • H1 blocker: Diphenhydramine 25-50mg IV
               • H2 blocker: Famotidine 20mg IV
               • Corticosteroids: Methylprednisolone 125mg IV
               • IV fluids for hypotension
               1. ◆

                  Decision

                  Response to Treatment?

                  Assess within 15-30 minutes

                  1. ✓

                     Outcome

                     Improving

                     Continue monitoring, discharge with EpiPen

                     • Observe 4-6 hours minimum
                     • Prescribe EpiPen
                     • Allergy referral
                     • Avoid trigger
                     1. ●

                        Action

                        Ongoing Monitoring

                        All patients require observation

                        • Serial airway exams
                        • Bradykinin attacks peak at 24h, resolve 48-72h
                        • HAE: Consider prophylaxis (C1-INH, lanadelumab)
                        • ACE-I: Document allergy, never rechallenge
                        • Order C4, C1-INH level if HAE suspected
                        1. ✓

                           Outcome

                           Disposition

                           Based on severity and response

                           • Admit: Any airway involvement, severe attacks, uncertain diagnosis
                           • ICU: Intubated, high-risk airway
                           • Discharge: Mild, resolved, with safety net and follow-up
                  2. ●

                     Action

                     Not Responding

                     Reconsider diagnosis

                     • May be bradykinin-mediated
                     • Try bradykinin-specific therapy
                     • Reassess for impending airway compromise
                     1. ●

                        Action

                        Bradykinin-Specific Treatments

                        Order based on availability and indication

                        • 1ST LINE - Tranexamic acid: 1g IV, can repeat (widely available)
                        • C1-INH CONCENTRATE (Berinert): 20 units/kg IV (first-line for HAE)
                        • Icatibant: 30mg SC (HAE; less effective for ACE-I induced)
                        • Ecallantide: 30mg SC (HAE only; 3% anaphylaxis risk)
                        • FFP: 2 units (if others unavailable; theoretical worsening risk)
            2. ●

               Action

               Bradykinin-Mediated

               Does NOT respond to epinephrine/antihistamines

               • ACE inhibitor: STOP drug permanently
               • Hereditary: C1-INH deficiency
               • Acquired: Associated with lymphoproliferative disorders
               • Duration typically 48-72h if untreated
               1. ●

                  Action

                  ACE Inhibitor-Induced

                  Most common cause of bradykinin angioedema

                  • STOP ACE inhibitor permanently
                  • Can occur after years of use
                  • Switch to ARB with caution (some cross-reactivity)
                  • May recur for weeks after stopping
               2. ●

                  Action

                  Hereditary Angioedema (HAE)

                  C1-INH deficiency - genetic disorder

                  • Family history, recurrent attacks
                  • Abdominal attacks common
                  • Low C4 level (screening test)
                  • Low C1-INH level or function confirms
      2. ●

         Action

         Airway Currently Stable

         Proceed with evaluation but remain vigilant

         • Can worsen rapidly over hours
         • Close monitoring essential
         • Serial airway exams