Anaphylaxis Health Article

Diagnosis

Anaphylaxis is diagnosed based on the rapid development of symptoms in response to a suspected allergen. Identification of the cause may be done with RAST testing, a blood test that identifies IgE reactions to specific allergens. Skin testing can also be done, but with care. Food challenges should be avoided.

Sometimes, the offending allergen is not readily apparent, and the diagnosis of anaphylaxis could be over-looked. Also, some of the symptoms resemble other conditions such as cardiac arrhythmia, myocardial infarction, seizure disorder, insulin reaction, and pulmonary embolism.

A detailed medical history taken of the patient before medical or surgical procedures may help in diagnosis if symptoms manifest. Often, the only evidence of anaphylactic reaction is anecdotal or self-reported surveys.

Treatment

Emergency treatment of anaphylaxis involves injection of adrenaline (epinephrine), which constricts blood vessels and counteracts the effects of histamine. Oxygen may be given, as well as intravenous replacement fluids. Antihistamines may be used for skin rash, and aminophylline for bronchial constriction. If the upper airway is obstructed, the insertion of a breathing tube or tracheotomy tube may be needed.

Treatment should be administered immediately. Epinephrine injected directly into muscle tissue is quick and extremely effective. Intravenous injections require specific calculations regarding the dilution of adrenaline in order for it to be administered. Epinephrine inhalers are not as effective, as are short-acting b-agonist inhalers used by persons suffering from asthma. These can prove fatal because they delay effective treatment.

Self-administered epinephrine devices such as EpiPen and EpiE-Z are life-saving tools. Patients must be properly trained in their use and instructed to keep these devices updated and close at hand.

Patients should also be monitored for 24 hours after the symptoms have subsided. Symptoms have been known to return several hours later when the patient has returned home from the hospital.

Prognosis

The rapidity of symptom development is an indication of the likely severity of reaction: the faster symptoms develop, the more severe the ultimate reaction. Prompt emergency medical attention and close monitoring reduces the likelihood of death. Nonetheless, death is possible from severe anaphylaxis. For most people who receive rapid treatment, recovery is complete.

Health care team roles

All medical personnel should be trained to recognize the symptoms of anaphylaxis and to use the proper emergency procedures. Nurses and physicians assistants need to ask patients about their history of allergy when preparing them for a doctor's visit or before invasive procedures. Physicians, lab personnel, and nurses need to routinely ask whether a person is allergic to medications and latex. Inquiries about food allergies can be very helpful when preparing to administer vaccinations or medications. A patient's allergy history may have changed since the last doctor's visit. Even a small reaction like a rash on initial exposure to an allergen can be an indicator that a patient may have a more serious reaction on subsequent encounters with the agent.

In the case of latex allergy in the wake of a surgical procedure, medical personnel will need to strip the operating room or the procedure room of all latex items. Some patients are so sensitive to latex in any form that even inhaling a latex particle in the air could be life threatening.

Prevention

Avoidance of the allergic trigger is the only reliable method of preventing anaphylaxis. For insect allergies, this requires recognizing likely nest sites, wearing long sleeves, and using insect repellant. Preventing food allergies requires knowledge of the prepared foods or dishes in which the allergen is likely to occur, reading labels, and carefully questioning about ingredients when dining out. Use of a Medic-Alert tag detailing drug allergies is vital to prevent inadvertent administration during a medical emergency. In addition, patients with latex sensitivity need to avoid using latex products of all kinds and must notify medical and dental personnel of their latex allergy.

People prone to anaphylaxis should carry an Epi-pen or Ana-kit, which contains an adrenaline dose ready for injection. They also should be carefully trained in its use.

KEY TERMS

Allergen—A substance that causes an allergic reaction.

Adrenocorticotropic hormone (ACTH)—A hormone normally produced by the pituitary gland, sometimes taken as a treatment for arthritis and other disorders.

Antibody—An immune system protein that binds to a substance from the environment.

Histamine—A substance produced by the immune system in response to an allergen.

NSAIDs—Non-steroidal anti-inflammatory drugs, including aspirin and ibuprofen.

Tracheostomy tube—A tube that is inserted into an incision in the trachea (tracheotomy) to relieve upper airway obstruction.

BOOKS

Lawlor Jr., G.J., T.J. Fischer, and D.C. Adelman. Manual of Allergy and Immunology. Boston/New York/Toronto/London: Little, Brown and Co., 1995.