From the Guidelines
Immediate treatment of anaphylactic shock requires prompt administration of epinephrine (adrenaline) as the first-line therapy, as emphasized by the most recent and highest quality study 1. For adults, administer 0.3-0.5 mg of 1:1000 (1 mg/mL) epinephrine intramuscularly into the mid-outer thigh, which can be repeated every 5-15 minutes if symptoms persist. For children, the dose is 0.01 mg/kg up to a maximum of 0.3 mg. After epinephrine administration, place the patient in a supine position with legs elevated unless respiratory distress is present. Establish intravenous access and administer fluid resuscitation with normal saline (20 mL/kg initially) to counter vasodilation. Supplemental oxygen should be provided to maintain oxygen saturation above 94%. Second-line medications include H1 antihistamines (diphenhydramine 25-50 mg IV/IM for adults), H2 blockers (ranitidine 50 mg IV for adults), and corticosteroids (methylprednisolone 125 mg IV for adults) to prevent biphasic reactions. Continuous monitoring of vital signs is essential. Epinephrine works by causing vasoconstriction, reducing mucosal edema, increasing cardiac output, and bronchodilation, effectively counteracting the life-threatening effects of anaphylaxis, as supported by 1. After resolution, patients should be observed for 4-8 hours due to the risk of biphasic reactions and should be prescribed an epinephrine auto-injector for future emergencies. Some key points to consider in the management of anaphylaxis include:
- The importance of prompt epinephrine administration, as delayed injection can be associated with poor outcomes, including fatality 1.
- The use of antihistamines and glucocorticoids as adjunctive therapy, but not as a replacement for epinephrine 1.
- The need for continuous monitoring of vital signs and the potential for biphasic reactions 1. The most recent study 1 provides a comprehensive update on the management of anaphylaxis, including the role of epinephrine, antihistamines, and glucocorticoids, and emphasizes the importance of prompt and effective treatment to prevent morbidity and mortality.
From the FDA Drug Label
1 INDICATIONS & USAGE Adrenalin® is available as a single-use 1 mL vial and a multiple-use 30 mL vial for intramuscular and subcutaneous use. Emergency treatment of allergic reactions (Type I), including anaphylaxis, which may result from allergic reactions to insect stings, biting insects, foods, drugs, sera, diagnostic testing substances and other allergens, as well as idiopathic anaphylaxis or exercise-induced anaphylaxis.
Epinephrine (IM) is used for the emergency treatment of anaphylactic shock. The signs and symptoms of anaphylaxis that epinephrine can help treat include:
- Flushing
- Apprehension
- Syncope
- Tachycardia
- Thready or unobtainable pulse associated with hypotension
- Convulsions
- Vomiting
- Diarrhea and abdominal cramps
- Involuntary voiding
- Airway swelling
- Laryngospasm
- Bronchospasm
- Pruritus
- Urticaria or angioedema
- Swelling of the eyelids, lips, and tongue 2
From the Research
Treatment of Anaphylactic Shock
- Anaphylaxis is a life-threatening allergological emergency that requires immediate recognition and treatment by a physician 3.
- The primary cause of anaphylaxis is often due to drugs, foods, and insect stings 3, 4.
- Emergency treatment for anaphylactic shock consists of:
- Intramuscular application of adrenaline (epinephrine) as the first-line treatment 3, 5, 6, 4.
- Volume substitution (fluid resuscitation) to treat intravascular volume depletion 3, 5, 6.
- Antihistamines and corticosteroids as second-line medications, which should not be given in lieu of, or prior to, epinephrine 3, 6, 4.
- Additional treatments may include:
- Patient observation and disposition should be individualized, as there is no well-defined period of observation after resolution of signs and symptoms 5, 6.
- Preventive measures after anaphylaxis include: