Extreme Type I Hypersensitivity Reactions Anaphylaxis Extreme Type I Hypersensitivity Reactions

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 And death 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