When managing allergy-related emergencies you must be aware of the possibility of acute airway obstruction and cardiovascular collapse. Immunology is the study of the body’s immune system and the five categories of stimuli that may provoke allergic reactions. An allergic reaction is an exaggerated immune response to any substance that can be internal or external. The body releases chemicals, histamines and leukotrienes, which contribute to an allergic reaction. Almost any substance can be an allergen. First the person becomes sensitized to the substance, then the immune system learns to recognize it. When exposed to it again there is an allergic reaction. Therefore some patients do not know what is causing their allergic reaction or realize they are having one at all. An allergic reaction may be mild and local – characterized by itching, redness, or tenderness. It can be severe and systemic, a condition known as anaphylaxis.
Anaphylaxis is an extreme allergic reaction that affects multiple organs. Some of the most common signs are as follows. Urticaria – hives, small areas of generalized itching or burning that appear as multiple small raised areas on the skin. There is angioedema or localized swelling in combination with wheezing and increased mucus production. There could be stridor (high-pitched sound) heard when breathing. There could also be hypotension and poor perfusion due to vasodilation. Also look out for gastrointestinal dysfunction like nausea, vomiting, and abdominal cramps. Common things that cause it are food, which accounts for 30% of deaths, medication, plants, chemicals, and insect bites and stings. In 33% of the deaths regarding stings, the victim had never experienced a reaction to prior stings. When removing the stinger do not use tweezers because that can further envenomate; use a card or a tongue depressor to scrape them off. There may be a wheal, which is a raised, swollen, well-defined area on the skin. Death typically occurs within the first 30 minutes.
When treating, attempt to remove the stinger by scraping with a stiff object such as a credit card; do not use tweezers because that can inject more venom. Give oxygen if needed. Epinephrine is the body’s normal sympathomimetic hormone; this means it mimics the sympathetic response. Epinephrine has various properties like reversing vasodilation and hypotension and elevating diastolic pressure and improving coronary blood flow. An indication for use is severe allergic reaction causing airway, breathing, or circulation compromise. Some contraindications are consult medical control when the patient has a history of heart disease or acute coronary syndrome, but none in a life-threatening emergency. The actions are vasoconstriction and increased cardiac contractility, bronchodilation. Side effects are tachycardia, sweating, pale skin, dizziness, headache, palpitations. Typical dose – Adults 0.3 mg (EpiPen) IM, children 0.15 mg (EpiPen Jr) IM. Concentration must be 1 mg/ml. To use or help a patient use the auto-injector you should receive a direct order from medical control or follow local protocol.
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