AnaphylaxisAnaphylaxis

Extreme Type I Extreme Type I Hypersensitivity ReactionsHypersensitivity Reactions

OverviewOverview

• Components of type I Components of type I hypersensitivityhypersensitivity

• Cause of type I hypersensitivityCause of type I hypersensitivity

• Effects of degranulationEffects of degranulation

• Systemic anaphylaxisSystemic anaphylaxis

• Emergency and Post-emergency Emergency and Post-emergency TreatmentTreatment

Components of Type I Components of Type I HypersensitivityHypersensitivity

• Allergen- Antigen (protein) Allergen- Antigen (protein) from various sources which from various sources which causes hypersensitivity causes hypersensitivity reaction in some peoplereaction in some people– Food, medication, insect products, Food, medication, insect products,

plant pollen, etc.plant pollen, etc.• Immunoglobulin E (IgE)- Immunoglobulin E (IgE)-

Antibodies, normally produced Antibodies, normally produced to protect against parasitic to protect against parasitic infection, instead produced infection, instead produced specific to the allergenspecific to the allergen

• Mast cells- Highly granular cells Mast cells- Highly granular cells with Fc receptors for IgEwith Fc receptors for IgE

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Cause of Type I Cause of Type I HypersensitivityHypersensitivity

• Allergen antigens affect approximately Allergen antigens affect approximately 10% of the population.10% of the population.

• These antigens cause the production These antigens cause the production of immunoglobulin E (IgE) antibodies.of immunoglobulin E (IgE) antibodies.

• IgE binds to Fc receptors on mast cells IgE binds to Fc receptors on mast cells • Upon subsequent exposure, the Upon subsequent exposure, the

allergen activates these sensitized allergen activates these sensitized cells causing degranulationcells causing degranulation

Cause of Type I Cause of Type I HypersensitivityHypersensitivity

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~immuno/part1/lec13/lec13_97.html~immuno/part1/lec13/lec13_97.html

Effects of DegranulationEffects of Degranulation

• When the granules release their contents, When the granules release their contents, histamine and various leukotrines, into the histamine and various leukotrines, into the surrounding tissue during a simple type I surrounding tissue during a simple type I hypersensitivity reaction the following hypersensitivity reaction the following results occur:results occur:– Smooth muscle cells contractSmooth muscle cells contract– Small blood vessels dilateSmall blood vessels dilate– Increase in bronchial mucus secretionsIncrease in bronchial mucus secretions

• However, anaphylaxis is much more However, anaphylaxis is much more seriousserious

Systemic anaphylaxisSystemic anaphylaxis

• Severe, life threatening type I Severe, life threatening type I reaction normally starting just reaction normally starting just minutes after exposureminutes after exposure

• Symptoms can include:Symptoms can include:– Cardiovascular: hypotension, chest pain, Cardiovascular: hypotension, chest pain,

cardiac arrest, faint pulse and shockcardiac arrest, faint pulse and shock

Symptoms ContinuedSymptoms Continued

– Dermatologic: Dermatologic: urticaria (hives), urticaria (hives), swelling, itchy skin, swelling, itchy skin, sensation of sensation of warmth, flushing, warmth, flushing, angioedema (rapid angioedema (rapid swelling) and rashswelling) and rash

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Symptoms ContinuedSymptoms Continued

– Gastrointestinal: nausea, cramps, vomiting, Gastrointestinal: nausea, cramps, vomiting, diarrhea, itchy mouth/throatdiarrhea, itchy mouth/throat

– Pulmonary: vasodilation of arterioles and Pulmonary: vasodilation of arterioles and constriction of bronchioles in the lungs, constriction of bronchioles in the lungs, respiratory distress, throat tightness, cough, respiratory distress, throat tightness, cough, nasal congestion, trouble swallowing, nasal congestion, trouble swallowing, respiratory arrestrespiratory arrest

• And deathAnd death

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Immediate TreatmentImmediate Treatment

• Epinephrine Epinephrine (adrenaline) is used (adrenaline) is used to treat severe to treat severe anaphylaxis. This is anaphylaxis. This is an immediate an immediate treatment to open treatment to open the airway and raise the airway and raise the blood pressurethe blood pressure

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Immediate TreatmentImmediate Treatment

• If the patient is not If the patient is not breathing perform breathing perform CPRCPR

• In any event In any event contact 911 contact 911 immediatelyimmediately

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Advanced TreatmentAdvanced Treatment

• Advanced medical treatment by EMTs or Advanced medical treatment by EMTs or ER personnel may include endotracheal ER personnel may include endotracheal intubationintubation

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Advanced TreatmentAdvanced Treatment

• Hypotension is usually treated with Hypotension is usually treated with IV fluids and “pressors,” drugs that IV fluids and “pressors,” drugs that raise the blood pressureraise the blood pressure

• Bronchodilators such as albuterol are Bronchodilators such as albuterol are used to open the airwayused to open the airway

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Post-emergency TreatmentPost-emergency Treatment

• After lifesaving measures are After lifesaving measures are successful the hypersensitive successful the hypersensitive reaction must be controlledreaction must be controlled– Antihistamines like diphenhydramineAntihistamines like diphenhydramine– Corticosteroids like prednisoneCorticosteroids like prednisone

Are given to further reduce symptomsAre given to further reduce symptoms

ReviewReview

• Components of type I Components of type I hypersensitivityhypersensitivity

• Cause of type I hypersensitivityCause of type I hypersensitivity

• Effects of degranulationEffects of degranulation

• Systemic anaphylaxisSystemic anaphylaxis

• Emergency and Post-emergency Emergency and Post-emergency TreatmentTreatment