Anaphylaxis

DESCRIPTION
* Anaphylaxis is a severe generalized allergic reaction characterized by widespread dilation of the blood vessels of the body, resulting in a marked drop in blood pressure. It is caused by an IgE (a type of an antibody) mediated reaction to an allergen.


SYMPTOMS
* Severe drop in blood pressure -- lightheadedness and fainting are common
* Respiratory distress -- severe wheezing in the lungs or spasm in the larynx (throat feels like it is closing off). Stridor (whistling sound) may be heard coming from the throat.
* Gastrointestinal tract muscles contract (spasm)
* Uterine muscles contract (spasm)
* Hives
* Lip swelling
* Tongue swelling
* Tryptase (a substance found in mast cells) is elevated 60-90 minutes after an attack.

CAUSE
* Medications
* Insect stings or bites, e.g., bee stings
* Certain foods, e.g., peanuts
* Latex (gloves)

TREATMENT
* Aqueous epinephrine 1:1000, 0.2 to 0.5 ml subcutaneously, or via intramuscular injection. May be repeated every 15 to 30 minutes.
* Rapid infusion of large volumes of intravenous fluids, such as normal saline, lactated Ringer's solution, plasma, colloid solutions, or plasma expanders
* Other vasopressive drugs, if not responsive to epinephrine, e.g., dopamine, norepinephrine, phenylephrine
* If airway obstruction occurs (or is impending), endotracheal intubation or tracheostomy will be needed.
* Beta 2 agonist inhaled (e.g., Albuterol) can help with bronchospasm.
* Intravenous theophylline may also be helpful with bronchospasm.
* Antihistamines H1 (e.g., Atarax, Benadryl) and H2 (Ranitidine) are adjunct therapies.
* Patients chronically on beta blockers (used for blood pressure, heart problems, and migraine prevention) may be refractory to epinepherine and may require higher doses of adrenergic drugs or intravenous Glucagon.
* Warning: 6 -12 hours after an anaphylactic reaction there may be a late phase response (a recurrence of symptoms), requiring monitoring (in a hospital) for 24 hours after an attack.

IF YOU SUSPECT THIS CONDITION
* If you have an Epi Pen, use it immediately as directed by your physician. Seek immediate emergency medical treatment as quickly as possible (in the United States dial 911). This condition is often fatal if not treated immediately.

PREVENTION
* There is no reliable way to truly prevent an attack, once exposed to the allergen (it can be treated afterwards).
* The best prevention is avoidance of inciting allergens. Allergy skin testing and RAST (radioallergosorbent test) testing can identify allergens (substances) to be avoided.
* Long term antihistamine and corticosteroid oral therapy may decrease the occurrence of attacks.
* Persons with a history of anaphylaxis should carry an Epi Pen with them at all times. This is self-injection epinephrine kit for emergencies.

SIMILAR CONDITIONS
* Angioedema
* Urticaria