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Anaphylaxis is a life-threatening allergic reaction to
foreign matter. It involves the whole body primarily affecting the
circulatory system, respiratory tract, alimentary tract, and the skin. It
occurs following exposure to an allergen and the body reacts by releasing
substances like histamine.
Histamine is responsible for the vasodilation effect which leads to
hypotension or a decreased blood pressure. The movement of fluid into the
interstitial space decreases blood volume which may lead to shock. In the
lungs fluid may leak into the alveoli producing pulmonary edema hence the
difficulty of breathing.
The signs and symptoms seen in this condition are due to histamine and other
substances released by the tissues. Airway narrowing produces the dyspnea
and wheezing. There are hives and angioedema (swelling underneath the skin)
present on the eyelids, lips, or throat which may further narrow down the
airway. There may also be vomiting, diarrhea, and abdominal pain, abnormal
heart rate, palpitation, dizziness,confusion, and cyanosis.
Common allergens include drugs such as penicillin, food such as peanuts,
seafoods,or eggs, insect bites, horse serum in the form of vaccines,
immunotherapeutic agents, and hormones. They enter the body through
inhalation, ingestion, or via injection.
Some drugs cause anaphylactoid reaction. This is an anaphylactic-like
reaction resulting from a toxic reaction. It has the same signs and
symptoms, complications, and treatment with the trye anaphylaxis.
There is always a previous exposure to the provocative substance. On
subsequent exposure an allergic reaction occur followed by onset of
symptoms. There is rapid deterioration involving the whole body hence the
condition requires immediate medical attention.
Control of airway, breathing, and circulation (ABC) is the first priority.
CPR can be done if necessary together with providing an airway by means of
endotracheal intubation or tracheostomy. Administer epinephrine as
necessary. IV fluids, corticosteroids, and antihistamines are also given. It
is very important to identify the allergen in order to prevent future
exposure.
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