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EPINEPHRINE AS TREATMENT FOR ANAPHYLAXIS AND ALLERGIC REACTIONS
Prompt assessment and treatment are critical in anaphylaxis, as respiratory or cardiac arrest and death can occur within minutes. Also, it is most responsive to treatment in its early phases:
Delayed epinephrine injection is associated with fatalities.
Indications and Contraindications
Indications for epinephrine include severe allergic reaction or hypersensitivity to exposed substance.
Contraindications are procedural:
- expired medication;
- discolored medication;
- prescription for another patient (not the patient’s drug).
...although additional caution must be used in patients who are
- have cardiac disease. [SEE BELOW]
Epinephrine's action slows allergic response, raises blood pressure, and dilates the bronchioles.
Its benefits in anaphylaxis are:
- may end the hyper-reactive efforts of the immune system.
- vasoconstriction (alpha-1 adrenergic effect) decreases edema and relieves pressure on upper airway obstructions,
- increasing blood pressure and fixing the shock. Also,
- increased rate and force of contraction(beta-1 adrenergic effect) of the heart increases perfusion;
- bronchodilation (beta-2 effect) and reduces the amount of histamine, tryptase or other inflammatory mediators released.
IM is Preferred Route
In anaphylaxis, epinephrine should be given IM preferentially, which allows for faster absorption than sub-Q and minimizes cardiac side effects.
Autoinjection Systems: The auto-injection systems are provided by a doctor’s order, must belong to the patient and must not be expired.
Prepare the injection site with alcohol and remove the needle cover. To administer, push the needle firmly into the lateral thigh and hold for ten seconds to allow the drug to be fully injected. Monitor the patient response, and dispose of the autoinjector in a sharps container.
Advanced providers, with proper training and if protocols allow, are more frequently drawing up and administering epinephrine through manual hypodermic needles and syringes, due to increasing prices and thus unavailability of epinephrine auto-injectors. Intramuscular and subcutaneous are the preferred routes of administration and dosages are generally 0.3 mg of epinephrine 1:1,000 for adults. Administer according to protocol.
- Adult Dosing: 0.3 - 0.5mg of 1:1,000 IM q 5 - 15 minutes; if patient deteriorates 0.1 - 0.5mg of 1:10,000 IVP q 5 - 15 minutes.
- Pediatric Dosing: 0.01mg/kg of 1:1,000 IM (6% to 19% require a second dose); if patient deteriorates 0.1 - 0.5mg of 1:10,000 IVP q 5 - 15 minutes.
Side effects include
- increased pulse rate and blood pressure,
- anxiety, and
- cardiac arrhythmias.
Dosing mistakes: Medication errors have occurred due to confusion with epinephrine products expressed as ratio strengths (e.g., 1:1000 vs 1:10,000).
Epinephrine 1:1000 = 1 mg/mL and is most commonly used IM.
Also, topical epinephrine is 1:1000. Vials of topical and injectable epinephrine look similar. Epinephrine 1:10,000 = 0.1 mg/mL and is used IV.
- cardiac ischemia,
- MI, palpitations, SVT,
- impaired memory,
- gangrene at the injection site.
- insulin resistance,
- lactic acidosis.
USE WITH CAUTION IN DIABETICS.
- nausea and vomiting.
- pulmonary edema (due to pulmonary constriction + cardiac stimulation), and
In elderly patients, there is a possible contraindication of coronary artery disease. In those instances, consider adjusting to renal or hepatic doses of Epinephrine.
Preferred Injection Site
The preferred injection site is the anterolateral aspect of the thigh.
Do not inject into the buttock: not only is it not always effective in treating anaphylaxis but has been associated with Clostridial infections (gas gangrene).
Serious skin and soft tissue infections, including necrotizing fasciitis and myonecrosis caused by Clostridia (gas gangrene), have been reported rarely at the injection site.
Cleansing skin with alcohol may reduce bacteria at the injection site, but alcohol cleansing does not kill Clostridium spores. Do not administer repeated injections at the same site (tissue necrosis may occur). Monitor for signs/symptoms of injection-site infection.