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Extreme Type I Hypersensitivity Reactions. Anaphylaxis. Overview. Components of type I hypersensitivity Cause of type I hypersensitivity Effects of degranulation Systemic anaphylaxis Emergency and Post-emergency Treatment. Components of Type I Hypersensitivity.
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Extreme Type I Hypersensitivity Reactions Anaphylaxis
Overview Components of type I hypersensitivity Cause of type I hypersensitivity Effects of degranulation Systemic anaphylaxis Emergency and Post-emergency Treatment
Components of Type I Hypersensitivity • Allergen- Antigen (protein) from various sources which causes hypersensitivity reaction in some people • Food, medication, insect products, plant pollen, etc. • Immunoglobulin E (IgE)- Antibodies, normally produced to protect against parasitic infection, instead produced specific to the allergen • Mast cells- Highly granular cells with Fc receptors for IgE Picture taken from library.thinkquest.org
Cause of Type I Hypersensitivity Allergen antigens affect approximately 10% of the population. These antigens cause the production of immunoglobulin E (IgE) antibodies. IgE binds to Fc receptors on mast cells Upon subsequent exposure, the allergen activates these sensitized cells causing degranulation
Cause of Type I Hypersensitivity Picture adapted from http://www-immuno.path.cam.ac.uk/ ~immuno/part1/lec13/lec13_97.html
Effects of Degranulation When the granules release their contents, histamine and various leukotrines, into the surrounding tissue during a simple type I hypersensitivity reaction the following results occur: Smooth muscle cells contract Small blood vessels dilate Increase in bronchial mucus secretions However, anaphylaxis is much more serious
Systemic anaphylaxis Severe, life threatening type I reaction normally starting just minutes after exposure Symptoms can include: Cardiovascular: hypotension, chest pain, cardiac arrest, faint pulse and shock
Symptoms Continued • Dermatologic: urticaria (hives), swelling, itchy skin, sensation of warmth, flushing, angioedema (rapid swelling) and rash Picture taken from megspeaks.blogspot.com Picture taken from www.desalex.com.br
Symptoms Continued • Gastrointestinal: nausea, cramps, vomiting, diarrhea, itchy mouth/throat • Pulmonary: vasodilation of arterioles and constriction of bronchioles in the lungs, respiratory distress, throat tightness, cough, nasal congestion, trouble swallowing, respiratory arrest • And death Picture taken from www.scielo.cl
Immediate Treatment • Epinephrine (adrenaline) is used to treat severe anaphylaxis. This is an immediate treatment to open the airway and raise the blood pressure Picture taken from www.forestpests.org Picture taken fromwww.fireengineering.com
Immediate Treatment • If the patient is not breathing perform CPR • In any event contact 911 immediately Picture taken from www.firelandsredcross.org
Advanced Treatment • Advanced medical treatment by EMTs or ER personnel may include endotracheal intubation Picture taken from healthlibrary.epnet.com
Advanced Treatment Hypotension is usually treated with IV fluids and “pressors,” drugs that raise the blood pressure Bronchodilators such as albuterol are used to open the airway Picture taken from www.houstontx.gov
Post-emergency Treatment After lifesaving measures are successful the hypersensitive reaction must be controlled Antihistamines like diphenhydramine Corticosteroids like prednisone Are given to further reduce symptoms
Review Components of type I hypersensitivity Cause of type I hypersensitivity Effects of degranulation Systemic anaphylaxis Emergency and Post-emergency Treatment