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A Shot in the Leg Could Save a Life
Abstract & Commentary
John P. Santamaria, MD, Affiliate Professor of Pediatrics, University of South Florida School of Medicine, Tampa, FL, is Associate Editor for Urgent Care Alert.
Dr. Santamaria reports no financial relationships relevant to this field of study.
Synopsis: Risk reduction entails confirmation of the trigger, discussion of avoidance of the relevant allergen, a written individualized emergency anaphylaxis action plan, and education of supervising adults with regard to recognition and treatment of anaphylaxis.
Source: Sicherer SH, et al. Self-injectable epinephrine for first-aid management of anaphylaxis. Pediatrics. 2007;119:638-646.
Concern about the potentially lethal effects of anaphylaxis center around respiratory compromise and cardiovascular collapse. Rapidly administered epinephrine by intramuscular injection in the vastus lateralis muscle is the most commonly accepted, as well as the best initial treatment. Failure to administer epinephrine promptly is one of the 3 factors associated with fatal anaphylaxis; the others being preexisting asthma and the adolescent age group. Although inhaled selective B2 adrenergic agonists (in children with known preexisting asthma) and oral H1 antihistamines are used as adjunctive agents, they will not relieve upper airway edema or shock and do not replace the indication for epinephrine.
The recommended dose of epinephrine for anaphylaxis is 0.01 mg/kg, up to 0.30 mg SQ or IM. The risks of prescribing an epinephrine syringe, ampule, and needle include overdosing, underdosing, and slower administration. Epinephrine autoinjectors are only available as 0.15 mg (EpiPen Jr.) and 0.30 mg (EpiPen) unit doses, which may not correspond to the recommended epinephrine doses based on per kilogram calculations. Due to the ease of use and predictable dosing compared to using a syringe and needle, Sicherer and colleagues recommend using the autoinjectors. They recommend using the autoinjector containing 0.15 mg of epinephrine for children weighing 10 to 25 kg and the autoinjector containing 0.30 mg of epinephrine for children weighing more than 25 kg.
Prescription of an epinephrine autoinjector is primarily indicated for those having a previous episode of anaphylaxis with respiratory or cardiovascular compromise, or a child who has experienced generalized acute urticaria following an insect sting. With the decision to prescribe an epinephrine autoinjector comes the responsibility to educate the patient and family regarding appropriate circumstances to dose the epinephrine, proper administration technique, and the need for prompt physician evaluation after epinephrine administration. Immediately after dosing the intramuscular epinephrine, it is important to call 911 for rapid medical evaluation and transport to an emergency facility. Also, it is important to maintain these medications within their expiration periods.
There are relatively few opportunities in medical practice to save lives so quickly and predictably as when using epinephrine to treat life-threatening anaphylaxis. Even more remarkably, the physician can exert this impact without being present at the time of the antigenic stimulus by properly equipping and educating the child and family.
The decision to use an autoinjector for IM administration of epinephrine, rather than a syringe and needle, is well founded. One only need compare the potential for error between the use of the autoinjector and needle/syringe. There is a predictable variant from recommended dosing when using the autoinjector. This is far preferable to the potentially more extreme and unpredictable dosing errors that occur when drawing up epinephrine into a syringe.
Admirably, Sicherer et al recommend the prescription of autoinjectors not only for children who have had respiratory or cardiovascular collapse associated with anaphylaxis but also those with generalized urticaria following an insect sting. Although not mentioned in this article, the child having generalized urticaria following food ingestion is also at risk. As a practical matter, it is prudent to supply the patient with multiple autoinjectors to meet his lifestyle needs. Most commonly a total of 3: one for home, one for school/work, and one for the car or purse.
Sicherer et al emphasize the need for the medical home to always prescribe epinephrine in the context of an anaphylaxis emergency action plan developed in consultation with the patient and family. The urgent care physician needs to determine his ability to provide these services or be sure the child will receive prompt follow-up by a primary care physician.