Emergency Treatment in Adult Patients (Campbell & Kelso, 2022)

Patients with anaphylaxis should be assessed and treated as rapidly as possible; respiratory or cardiac arrest and death can occur within minutes.

1. Remove the cause, if possible, such as stopping the infusion of a suspected medication.
2. Call for help (i.e., resuscitation team if in a hospital or 911 in the community)
3. Epinephrine (1 mg/mL) is the most critical first treatment. There are no absolute contraindications to epinephrine in the setting of anaphylaxis and it is the treatment of choice for anaphylaxis of any severity.
   1. Give 0.3 to 0.5 mg epinephrine intramuscularly (IM), preferably in the mid-outer thigh. Repeat every 5 to 15 minutes (or more frequently), as needed.
      1. If an exact dose can be drawn up, use 0.01 mg/kg (maximum of 0.5 mg)
      2. If an autoinjector is used:
         1. Children weighing less than 25 kg, give 0.15 mg
         2. Children weighing over 25 kg, give 0.3 mg
   2. Most patients respond to one, two, or at most, three doses.
   3. IM injection is preferred over IV bolus because it is faster and safer.
   4. If symptoms do not improve, prepare IV epinephrine for continuous infusion.
      1. Start IV epinephrine infusion at 0.1 mcg/kg/minute (range: 0.05 to 0.2 mcg/kg/minute) and titrate as needed.
4. Assess airway, breathing, circulation, mental status, skin and body weight.
   1. Immediate intubation if impending airway obstruction from angioedema. Intubation should be performed by the most experienced clinician available.
5. Place patient in recumbent position, if tolerated, and elevate lower extremities. If there is significant upper airway swelling, keep the patient upright. If patient is vomiting, place patient semirecumbent with lower extremities elevated.
6. Oxygen: apply 15 L/minute via nonrebreather mask or up to 100% oxygen, as needed.
7. Rapid IV fluid bolus:
   1. Insert two large-bore IV catheters, 14 to 16 gauge.
   2. Begin immediately in patients who present with orthostasis, hypotension, or incomplete response to IM epinephrine.
   3. Normal saline is the preferred solution.
   4. Rapid infusion of 1 to 2 liters IV in the first minutes of treatment; repeat as needed. Large volumes of fluid (i.e., up to 7 liters) may be needed.
   5. In normotensive adults, infuse normal saline at 125 mL/hour to maintain IV access.
8. Albuterol (salbutamol): for bronchospasm resistant to IM epinephrine, give 2.5 to 5 mg in 3 mL saline via nebulizer, or 2 to 3 puffs by metered dose inhaler. Repeat as needed.
9. Monitoring:
   1. Continuous noninvasive hemodynamic monitoring (blood pressure, heart rate, respiratory rate)
   2. Oxygen saturation by pulse oximetry
   3. Urine output should be monitored in patients receiving IV fluid resuscitation for severe hypotension or shock.
   4. If cardiac arrest occurs, perform cardiopulmonary resuscitation with continuous chest compressions.

4. Adjunctive Therapies (Campbell & Kelso, 2022)

   • H1 antihistamine for relief of urticaria and itching only; these drugs do not treat upper or lower airway obstruction, hypotension or shock.
     • Cetirizine 10 mg IV, administer over 1 to 2 minutes OR
     • Diphenhydramine 25 to 50 mg IV, administer over 5 minutes, repeat every 4 to 6 hours as necessary
   • H2 antihistamine: famotidine 20 mg IV, administer over 2 minutes
   • Bronchodilators: for bronchospasm not responsive to epinephrine, albuterol or salbutamol should be administered by mouthpiece (or facemask) and nebulizer/compressor, as needed
   • Glucocorticoid: may be beneficial for patients with severe symptoms requiring hospitalization or for those with known asthma and significant bronchospasm that persists after other anaphylaxis symptoms have resolved. Methylprednisone 125 mg IV (or 1 to 2 mg/kg/day) for 1 to 2 days; may be stopped without a taper.