Download Anaphylaxis

Severe Allergic Reaction
(Anaphylactic Shock)
过敏性休克
Fang Hong 方 红
1st Affiliated Hospital, Zhejiang University
Overview
• Anaphylaxis is a severe allergic reaction that occurs
rapidly and causes a life-threatening response involving
the whole body. This reaction can lead to difficulty
breathing and shock ultimately leading to death.
• An anaphylactic reaction occurs when the body's
immune system overreacts to an antigen, which it
recognizes as an "invader" or foreign substance.
• The reaction usually occurs within seconds to minutes of
exposure.
Causes
Triggers of allergic reactions may include:
• Drugs, prescription and over-the-counter medication
and blood or blood products;
• Venom of stinging insects;
• Foods, especially high-protein foods , most commonly,
fish, nuts, fruit, wheat, milk, eggs, soy products;
• Food additives, such as sulfites;
• Other substances ,such as latex (natural rubber);
• Dyes and contrast materials, used during radiologic
procedures or tests;
• Often, however, the trigger is unknown.
Pathogenesis
• The body's white blood cells produce antibodies as
a reaction to that antigen. The antibodies circulate
in the bloodstream and attach themselves to mast
cells in the body.
• In an allergic reaction, the antibody is called
immunoglobulin E, or IgE.
• When the antibodies come in contact with the
antigen, they signal other cells to produce mediators.
Histamine is an one of the mediators.
• The effects of these mediators on organs and
tissues of the body cause the symptoms of the
reaction.
Symptoms
•
The symptoms of anaphylaxis can vary. In some people, the reaction begins
very slowly, but in most the symptoms appear rapidly and abruptly.
•
The most severe and life-threatening symptoms are difficulty breathing and
loss of consciousness.
•
Difficulty breathing is due to swelling and/or spasm in the airways. In very rare
cases, breathing can stop altogether.
•
Loss of consciousness is due to dangerously low blood pressure, which is
called "shock."
•
In the most serious cases, the heart can stop pumping altogether.
•
These events can lead to death from anaphylaxis.
Symptoms
• Generally, a reaction must involve at least two different
body systems, such as skin and heart.
• Skin: Most anaphylactic reactions involve the skin.
• Wheals (raised bumps): Hives can cause severe itching;
• Generalized erythema (redness);
• Swelling in the face, eyelids, lips, tongue, throat, hands,
and feet.
Symptoms
• Breathing: Difficulty breathing, wheezing, chest tightness,
coughing, hoarseness, nasal congestion, sneezing;
• Cardiovascular: Blood pressure may drop to dangerously
low levels, rapid or irregular heart beat; dizziness,
faintness; loss of consciousness, collapse;
• General: Tingling or sensation of warmth, difficulty
swallowing; Nausea, vomiting; Diarrhea, abdominal
cramping, bloating; Anxiety, fear, feeling that you are
going to die.
Medical Care
• Anaphylaxis is a medical emergency and requires
immediate treatment in an emergency department of a
hospital.
• If swelling develops rapidly, particularly involving the
mouth or throat, and the patient has trouble in
breathing or feels dizzy, light-headed, or faint, go
immediately to the nearest emergency department or
call an ambulance.
Treatment
• The first priority in the emergency department is to
protect the airway (breathing) and maintain adequate
blood pressure.
• The emergency team will make sure that your airway is
open and that you are getting adequate oxygen.
• Oxygen may be given through tubes into the nose or by
face mask.
• In severe respiratory distress, mechanical ventilation
may be required.
Treatment
• If blood pressure is dangerously low, medication to
increase blood pressure will be given.
• An intravenous (IV) catheter may be inserted in order to
give saline solution to help boost blood pressure.
• The IV line may also be used to give medication.
Treatment
Medications include:
•
Epinephrine (0.5ml) should be given by injection into the muscle, through an
IV line, or by injection under the skin;
•
H1-receptor blockers/antihistamines: May be given by IV, by injection in the
muscle, or by mouth;
•
Inhaled beta-agonists: Used to treat bronchospasm (spasms in the lung)
and dilate the airways;
•
Corticosteroids: Help to decrease the severity and recurrence of symptoms;
may be given orally, injected in muscle, or by IV line;
•
If low blood pressure does not improve, additional medications, such as
dopamine, may be given.
Keywords
• Severe allergic reaction (anaphylactic shock);
• Allergy;
• Antibodies, antibody, antigen;
• Immunoglobulin E, IgE;
• Epinephrine.
Question
• Please describe your experience
with anaphylaxis.