From: World Allergy Organization Guidelines for the Assessment and Management of Anaphylaxis
Strength of Recommendationsa | B-C (As Defined in Footnote)a |
---|---|
Pharmacologic effects when given by injectionb | At alpha-1 adrenergic receptor |
 | Increases vasoconstriction and increases vascular resistance (in most body organ systems)c |
 | Increases blood pressure |
 | Decreases mucosal edema in the airways |
 | At beta-1 adrenergic receptor |
 | Increases cardiac contraction force |
 | Increases heart rate |
 | At beta-2 adrenergic receptor |
 | Decreases mediator release |
 | Increases bronchodilation |
Clinical relevance | Increases blood pressure and prevents and relieves hypotension and shock |
 | Decreases upper airway obstruction, eg. in larynx |
 | Decreases urticaria and angioedema |
 | Decreases wheezing |
Potential adverse effects after the usual epinephrine dose of 0.01 mg/kg of a 1:1,000 (1 mg/mL) solution intramuscularlyd (to a maximum of 0.5 mg [adult] or 0.3 mg [child]) | Pallor, tremor, anxiety, palpitations, dizziness, headache; these symptoms indicate that a pharmacologic dose has been injected |
Potential adverse effects after epinephrine overdose (eg. overly rapid intravenous infusion, intravenous bolus dose, or dosing error, eg. intravenous administration of an undiluted 1:1,000 (1 mg/mL) solutione) | Ventricular arrhythmias, hypertension, pulmonary edema; note that the heart itself is a potential target organ in anaphylaxis; therefore, acute coronary syndromes (angina, myocardial infarction, arrhythmias) can also occur in untreated anaphylaxis in patients with known coronary artery disease, in those in whom subclinical coronary artery disease is unmasked, and even in patients (including children) without coronary artery disease in whom the symptoms are due to transient vasospasm |
Reasons why the intramuscular route is preferred over the subcutaneous route for initial treatment of anaphylaxis | Epinephrine has a vasodilator effect in skeletal musclec; skeletal muscle is well-vascularized; after intramuscular injection into the vastus lateralis (mid-anterolateral thigh), absorption is rapid and epinephrine reaches the central circulation rapidly; rapid absorption is important in anaphylaxis, in which the median times to cardiorespiratory arrest are reported as 5 minutes (iatrogenic, eg. injected medication), 15 minutes (stinging insect venom), 30 minutes (food) |
Reasons for apparent lack of response to epinephrine | Error in diagnosis, patient suddenly stands or sits (or is placed in the upright position) after epinephrine injection; rapid anaphylaxis progression; patient taking a beta-adrenergic blocker or other medication that interferes with epinephrine effect; epinephrine injected too late; dose too low on mg/kg basis; dose too low because epinephrine is past expiry datef; not enough injection force used; route not optimal; injection site not optimal; other |