Anaphylaxis Management (GA²LEN International Consensus 2024)

Algorithm Steps

1. ▶

   Start

   Suspected Anaphylaxis

   Acute onset of multisystem involvement after exposure

   1. ◆

      Decision

      Anaphylaxis Criteria Met?

      Clinical diagnosis - do not delay for labs

      • CRITERION 1: Skin + respiratory OR cardiovascular compromise
      • CRITERION 2: ≥2 systems after likely allergen: skin, respiratory, GI, cardiovascular
      • CRITERION 3: Hypotension after KNOWN allergen
      • Skin signs may be absent in 10-20% of cases
      1. ●

         Action

         ⚡ EPINEPHRINE IM - FIRST LINE

         Anterolateral thigh - DO NOT DELAY

         • Adult: 0.3-0.5 mg IM (1:1000 = 1mg/mL)
         • Child: 0.01 mg/kg IM (max 0.3mg)
         • Auto-injector: 0.3mg (>25kg) or 0.15mg (<25kg)
         • May repeat q5-15 min if needed
         • THERE IS NO CONTRAINDICATION IN ANAPHYLAXIS
         1. ●

            Action

            Position Patient

            Supine with legs elevated (if tolerated)

            • Trendelenburg if hypotensive
            • Sitting if respiratory distress
            • Left lateral decubitus if pregnant
            • DO NOT sit/stand up suddenly
            1. ◆

               Decision

               Response to Epinephrine?

               Reassess within 5-15 minutes

               • Improvement in BP, breathing, symptoms
               • If no response, repeat epinephrine
               • After 2-3 doses, consider IV epinephrine
               1. ●

                  Action

                  Repeat Epinephrine IM

                  May repeat q5-15 min x 2-3 doses

                  • Same dose as initial
                  • Different injection site preferred
                  • Continue until response or IV access
                  1. ◆

                     Decision

                     Refractory to IM Epinephrine?

                     After 2-3 IM doses, consider IV epinephrine

                     1. ⚠

                        Warning

                        IV Epinephrine Infusion

                        For refractory anaphylaxis ONLY - requires monitoring

                        • Dilute: 1mg in 100mL NS (10 mcg/mL)
                        • Start: 1-4 mcg/min, titrate to effect
                        • Requires cardiac monitoring
                        • ICU setting preferred
                        • Consider glucagon if on beta-blockers
                        1. ✓

                           Outcome

                           ICU Admission

                           Refractory or severe - ongoing monitoring

                     2. ●

                        Action

                        Observation Period

                        Monitor for biphasic reaction

                        • Minimum 4-6 hours for mild reactions
                        • 8-12 hours for moderate-severe
                        • 24 hours if prior biphasic reaction
                        • Biphasic occurs in 1-20% of cases
                        1. ●

                           Action

                           Consider Labs

                           Do NOT delay treatment for labs

                           • Serum tryptase: 15min-3hr after onset
                           • Repeat at 24hr and baseline (2 weeks)
                           • Helps confirm diagnosis retrospectively
                           • May identify mastocytosis
                           1. ●

                              Action

                              Discharge Planning

                              Patient education and follow-up

                              • Prescribe epinephrine auto-injector (2 devices)
                              • Teach auto-injector technique
                              • Written anaphylaxis action plan
                              • Referral to allergist
                              • MedicAlert bracelet recommendation
                              • Return immediately if symptoms recur
                              1. ✓

                                 Outcome

                                 Resolved

                                 Symptoms controlled, safe for discharge

               2. ●

                  Action

                  Adjunct Therapies

                  AFTER epinephrine - never delay epinephrine for these

                  • IV fluids: NS bolus 1-2L (adults), 20mL/kg (peds)
                  • Oxygen: High-flow, maintain SpO2 >94%
                  • Albuterol: For bronchospasm not responsive to epi
                  • Antihistamines: H1 (diphenhydramine) + H2 (famotidine)
                  • Corticosteroids: May reduce biphasic reactions (evidence limited)
         2. ●

            Action

            Call for Help

            Activate emergency response/code team

            • Call resuscitation team
            • Note time of onset
            • Identify potential trigger
            • Prepare for escalation
         3. ●

            Action

            Remove Trigger

            If identifiable and safe to do so

            • Stop IV medications/contrast
            • Remove stinger (any method)
            • DO NOT delay epinephrine to remove trigger
      2. ●

         Action

         Consider Other Diagnoses

         Vasovagal, anxiety, other causes

         • Vasovagal syncope (pallor, bradycardia)
         • Panic attack (no objective signs)
         • Vocal cord dysfunction
         • Mastocytosis/mast cell activation
         • Hereditary angioedema (no urticaria)