Anaphylaxis Recognition and Treatment

Recognition of Anaphylaxis

• The American Academy of Pediatrics recommends confirming anaphylaxis by identifying acute onset with skin/mucosal involvement and respiratory compromise or hypotension/syncope, or two or more organ systems involved after allergen exposure, which may include skin, respiratory, cardiovascular, or gastrointestinal symptoms 1, 2
• The American Academy of Pediatrics also notes that isolated hypotension after known allergen exposure can be a sign of anaphylaxis, and that skin signs may be absent in 10% of anaphylaxis cases 1, 2

Immediate Administration Steps

• The American Academy of Pediatrics recommends using autoinjector options such as 0.15 mg or 0.3 mg, with the appropriate dose depending on the patient's weight 3
• Intramuscular injection in the vastus lateralis achieves peak plasma concentrations in 8±2 minutes, compared to 34±14 minutes with subcutaneous deltoid injection, as noted by the American Academy of Pediatrics 1, 2

Repeat Dosing Protocol

• The American Academy of Pediatrics recommends repeating injection every 5-10 minutes if symptoms fail to resolve or worsen, with 6-28% of patients requiring a second dose 3

Concurrent Management

• The American Academy of Pediatrics recommends calling 911 or activating the resuscitation team immediately, positioning the patient supine with legs elevated, and never allowing standing or walking, as this increases mortality risk 3
• Additional interventions such as oxygen, IV fluids, antihistamines, and corticosteroids may be necessary, as noted by the American Society of Hematology 4

Severe/Refractory Cases

• The American Society of Hematology recommends administering a normal saline bolus of 1000-2000 mL for adults, and considering IV epinephrine infusion, hydrocortisone, and famotidine for severe cases 4
• The American Academy of Pediatrics notes that IV epinephrine carries significant risk of dilution/dosing errors and serious adverse effects, and that the intramuscular route is safer and preferred for first-line treatment 1, 2

Post-Administration

• The American Academy of Pediatrics recommends transporting the patient to the emergency department via EMS for observation, even if symptoms resolve, and prescribing two autoinjectors for home use 3

Anaphylaxis Treatment with Epinephrine

Dosing and Administration

• The maximum single dose of epinephrine for adults is capped at 0.5 mg, despite body weight, as higher doses increase cardiac adverse effects without improving outcomes, according to the American Heart Association and the American Academy of Pediatrics 5, 6

Safety Considerations

• Higher doses of epinephrine increase cardiac adverse effects without improving outcomes, with a recommended maximum single dose of 0.5 mg for adults, as stated by the American Heart Association and the American Academy of Pediatrics 5, 6

Intramuscular Epinephrine Dosing for Anaphylaxis in Adults

Introduction to Anaphylaxis Treatment

• The American Academy of Allergy, Asthma, and Immunology recommends that there is no maximum number of IM epinephrine 1:1000 doses for anaphylaxis—repeat every 5 minutes as needed until symptoms resolve, with most patients requiring 1-2 doses but some needing more 7, 8, 9

Repeat Dosing Protocol

• Epinephrine can be repeated every 5 minutes as clinically needed to control symptoms and increase blood pressure, with the interval between injections liberalized to permit more frequent administration if deemed appropriate 7, 10

Clinical Reality of Repeat Dosing

• Approximately 10-20% of patients with anaphylaxis require more than one dose of epinephrine before symptom recovery 8, 9, 11
• Some patients require doses at intervals longer than 15 minutes, though guidelines recommend dosing as frequently as every 5-15 minutes 8, 9, 11

Standard Adult Dosing

• The standard dose is 0.01 mg/kg of 1:1000 (1 mg/mL) solution, with a maximum single dose of 0.5 mg per injection, administered via intramuscular injection into the anterolateral thigh (vastus lateralis muscle) 7, 8, 11, 12
• Administer immediately upon recognition of anaphylaxis, then repeat every 5 minutes as needed 7, 10

When to Escalate Beyond IM Epinephrine

• If a patient fails to respond to multiple IM doses, consider transitioning to IV epinephrine infusion, which requires continuous hemodynamic monitoring and starting infusion at 1-4 mcg/min, titrating up to maximum 10 mcg/min 8, 9, 11, 12

Critical Safety Points

• There is no absolute contraindication to epinephrine use in anaphylaxis, even in elderly patients or those with cardiac disease, as the risk of death from untreated anaphylaxis far exceeds the risk of epinephrine-related adverse effects 12

Common Pitfalls to Avoid

• Delaying epinephrine administration can be fatal, and fatalities are associated with delayed epinephrine, not with giving multiple doses 7, 12
• Stopping at one dose prematurely can lead to persistent or progressing symptoms, and if symptoms persist or progress, continue dosing every 5 minutes 7, 8, 9
• Confusing concentrations can lead to incorrect administration, and always use 1:1000 (1 mg/mL) for IM injection; 1:10,000 is reserved for IV use only 8, 9, 11

Pharmacologic Rationale

• Epinephrine has a rapid onset of action within minutes but is quickly metabolized, making its effect short-lived, necessitating repeat dosing when the initial response is inadequate or symptoms recur 8, 9, 11
• The number of doses should be determined by clinical response rather than an arbitrary maximum, with safety monitoring for each subsequent dose 7, 10, 12

Epinephrine Dosing for Adult Anaphylaxis

Intravenous (IV) Administration - Reserved for Specific Circumstances Only

• The American Academy of Allergy, Asthma, and Immunology recommends IV epinephrine should only be used in specific situations, including cardiac arrest, as stated by the Journal of Allergy and Clinical Immunology 13
• The starting infusion rate for IV epinephrine is 1-4 mcg/min, titrated up to a maximum of 10 mcg/min based on clinical response, according to the Journal of Allergy and Clinical Immunology 13
• Preparation method for IV epinephrine involves adding 1 mg (1 mL) of 1:1000 epinephrine to 250 mL of D5W to yield 4.0 mcg/mL concentration, then infusing at 15-60 drops/min with microdrop apparatus, as recommended by the Journal of Allergy and Clinical Immunology 13

Anaphylaxis Treatment with Epinephrine

Initial Dosing and Administration

• The intramuscular route in the lateral thigh achieves peak plasma concentrations in 8±2 minutes, compared to 34±14 minutes with subcutaneous deltoid injection, as recommended by the American Academy of Allergy, Asthma, and Immunology 14

IV Epinephrine Preparation and Dosing

• Add 1 mg (1 mL) of 1:1000 epinephrine to 250 mL of D5W to yield a concentration of 4.0 mcg/mL, as suggested by the American Heart Association 14
• Titrate up to a maximum of 10 mcg/min based on clinical response and side effects, according to the American College of Cardiology 15

Adjunctive Therapies

• Consider H1 antihistamine: Diphenhydramine 25-50 mg parenterally, as recommended by the American Academy of Allergy, Asthma, and Immunology 15
• Consider H2 antihistamine: Ranitidine 50 mg IV over 5 minutes, in combination with H1 antihistamine, as suggested by the American Gastroenterological Association 15, 16

Post-Treatment

• Prescribe two epinephrine autoinjectors (0.3 mg) for home use with proper instruction, as recommended by the American Academy of Allergy, Asthma, and Immunology 16
• Refer to allergist-immunologist for follow-up, according to the American College of Allergy, Asthma, and Immunology 16