ANAPHYLAXIS
Anaphylactic reactions don't make up a major percentage of emergency calls now that peope carry epinephrine and are generally able to get to hospital by other means. That being said, there are many situations where a patient may not have an epi-pen, may be a child at elementary school, or may simply prefer to travel with paramedics to the hospital. Anaphylaxis is a life-threatening reaction that needs to be taken seriously. Therefore, it is important for paramedics to be able to recognize the signs and symptoms, and to be able to treat it appropriately before it progresses to a critical stage.
What is anaphylaxis?
The immune system of our bodies is very good at doing one thing: recognizing invaders. In the case of a virus or a bacteria, antibodies are created after each exposure in order to allow us to recognize them in the future and mount a defence. Allergic reactions are a form of immune-mediated response to a perceived invader. In a typical allergic reaction, the body's immune system deems a chemical or substance to be threatening, and creates antibodies to react to it in the future. In the case of allergic reaction we create IgE (Immunoglobulin E), which is an antibody that is involved in the inflammatory response to a perceived threat. When exposed to an antigen, the body may trigger a “normal” allergic reaction that is localized to the site of exposure. This may result in urticaria (hives), rhinorrhea (runny nose), pruritis (itching), etc. The typical allergic reaction is inconvenient, but rarely life-threatening. It represents local inflammatory response, capillary dilation, and histamine release. It is usually self limiting and can be relieved with anti-histamines.
Anaphylaxis is an ATYPICAL reaction that occurs when local exposure to an antigen triggers systemic IgE activity, histamine and leukotriene release. The result is widespread vasodilation, and distributive shock. The key feature that separates allergic reaction from anaphylaxis is that a typical reaction only affects one body system, while anaphylaxis affects 2 or more body systems.
Neurological: Dizziness, weakness, confusion.
Cardiac: Hypotension, Tachycardia.
Respiratory: Bronchoconstriction, larygospasm
GI/GU: Nausea, vomiting, urge to defecate.
Integumentary: Urticaria, Pruritis
Additional things to watch for are:
Complaints of chest tightness or tightness in the throat.
Generalized itching.
Heightened anxiety or drowsiness
Treatment is actually relatively simple once we have reached the diagnosis:
Epinephrine 1:1000 0.01mg/kg to a max of 0.5mg IM q5min to a max of 2 doses
Benadryl: 25-50mg IM/IV single dose
IV cannulation with potential fluid bolus if hypotension is present
Salbutamol/albuterol 600-800mcg for bronchoconstriction
Supplemental oxygen as needed
(Local protocols may vary, this is just my local guideline)
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