Anaphylaxis
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ANAPHYLAXIS. Anaphylaxis Objectives. Upon completion the student will be able to: Define anaphylaxis Define antigen List ways an antigen can be introduced into the body Define antibody Describe the pathophysiology of allergic reactions and anaphylaxis. Anaphylaxis Objectives.

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Anaphylaxis

ANAPHYLAXIS


Anaphylaxis objectives

AnaphylaxisObjectives

Upon completion the student will be able to:

  • Define anaphylaxis

  • Define antigen

  • List ways an antigen can be introduced into the body

  • Define antibody

  • Describe the pathophysiology of allergic reactions and anaphylaxis


Anaphylaxis objectives1

AnaphylaxisObjectives

  • Discuss the effects of allergic reactions and anaphylaxis on the following body systems:

  • Skin

  • Respiratory

  • Cardiovascular

  • Gastrointestinal

  • Nervous

  • Describe the clinical presentation of the patient suffering an allergic reaction and anaphylaxis


Anaphylaxis objectives2

AnaphylaxisObjectives

  • Discuss the assessment of the patient suffering an allergic reaction and anaphylaxis

  • Describe the management of a patient with a severe allergic reaction

  • Describe the actions of the following medications, and relate their usage in the management of allergic reactions and anaphylaxis:

  • Oxygen

  • Epinephrine

  • Antihistamines

  • Corticosteroids

  • Beta Agonists


Introduction

Introduction

  • An acute, generalized, and violent antigen-antibody reaction - the most severe from of an allergic reaction - that may be rapidly fatal even with prompt and appropriate emergency medical care.

  • Develops in seconds to minutes after ingestion, injection, inhalation or absorption of an antigenic substance.


Immune system

Immune System

  • Plays a central role in allergies and anaphylaxis.

  • Components of the immune system can be found in the blood, the bone narrow, the connective tissues, and in the lymphatic system.


Immune system1

Immune System

  • The immune response is a series of complex events with the goal being the destruction or inactivation of pathogens, abnormal cells, or foreign molecules such as toxins.

  • This can be accomplished through two mechanisms:

    1.Cellular Immunity

    2.Humoral Immunity


Cellular immunity

Cellular Immunity

  • Derived from special leukocytes called t lymphocytes.

  • Originate in the thymus and are primarily responsible for fighting infections of biological agents living certain body cells, including tuberculosis, many viral infections, and most fungal infections.

  • Involves the movement of WBC to attack and eliminate.


Humoral immunity

Humoral Immunity

  • More complicated.

  • Derived from B lymphocytes and results in the formation of antibodies. There are five classes of human antibodies (immunoglobulins)

  • They include:

    1.IgM - antibody that responds immediately


Humoral immunity1

Humoral Immunity

2.IgG - antibody that has “memory” and recognizes a repeatedly invading infection

3.IgA - antibody present in the mucous membranes

4.IgE - antibody contributing to allergic and anaphylactic responses

5.IgD - antibody present in the lowest concentration


Humoral immunity2

Humoral Immunity

  • Begins with exposure of the body to an antigen. The antibodies seek out the invading antigen and combine, forming what is commonly called the antigen-antibody complex. This large complex is subsequently removed by scavenger cells such as macrophages.


Humoral immunity3

Humoral Immunity

  • If the body has never been exposed to a particular antigen, the reaction is totally different.

  • Initial response to an antigen is called the primary response. It takes the cellular and humoral components several days to respond to a primary antigen exposure. But other antibodies assist and develop memories of the particular antigen.


Humoral immunity4

Humoral Immunity

  • This way when the body is exposed to the same antigen again there is a secondary response which is much faster than the original.


Allergies

Allergies

  • Initial exposure of an individual to an antigen is referred to as sensitization.

  • This results in an immune response. Subsequent exposure induces a much stronger secondary response

  • Hypersensitivity is an unexpected and exaggerated reaction to a particular antigen, resulting in some discomfort for the individual


Allergies1

Allergies

  • Hypersensitivity is often used synonymously with the term allergy.

  • Two types of hypersensitivity reactions:

    1.Delayed

    2.Immediate


Delayed hypersensitivity

Delayed Hypersensitivity

  • Result of cellular immunity and does not involve antibodies.

  • Occurs in hours and days following exposure

  • Most commonly results in skin rash and is often due to exposure to certain drugs and chemicals

  • Common example: rash from poison ivy


Immediate hypersensitivity

Immediate Hypersensitivity

  • Examples of immediate hypersensitivity include: hay fever, drug allergies, food allergies and asthma.

  • Some individuals have an allergic tendency, known as atopy. This is usually genetic and characterized by the presence of IgE

  • An antigen that causes the release of IgE is referred to as an allergen


Immediate hypersensitivity1

Immediate Hypersensitivity

  • After exposure to an allergen, large quantities of IgE are released.

  • IgE becomes attached to membranes of basophils and mast cells

  • Basophils and mast cells are specialized cells of the immune system which contain chemicals that assist in the immune response.


Immediate hypersensitivity2

Immediate Hypersensitivity

  • When the allergen binds to IgE attached to the mast cells and basophils these cells release histamine, heparin.

  • Mast cells and basophils are referred to as granulocytes and histamine are stored in the granules of basophils and mast cells.

  • The release process of these substances is referred to as degranulation


Immediate hypersensitivity3

Immediate Hypersensitivity

  • The reaction that takes place is referred to as an allergic reaction.

  • Histamine is the principal chemical mediator of an allergic reactions.

  • Histamine causes bronchoconstriction, increased intestinal motility, vasodilation, and increased vascular permeability.


Immediate hypersensitivity4

Immediate Hypersensitivity

  • This increased permeability is what causes the leakage of fluid from the circulatory system into the surrounding tissue.

  • Two classes of histamine receptors:

    1.H1 cause bronchoconstriction and contraction of the intestines

    2.H2 cause peripheral vasodilation and secretion of gastric acids


Immediate hypersensitivity5

Immediate Hypersensitivity

  • The goal of histamine release is to limit the body’s exposure to the antigen

  • Bronchoconstriction decreases the possibility of the antigen entering through the respiratory tract

  • Increased gastric acid production helps destroy ingested antigen


Immediate hypersensitivity6

Immediate Hypersensitivity

  • Increased intestinal motility serves to move the antigen quickly through the GI system with minimal absorption

  • Vasodilation and capillary permeability help remove the allergen from the circulation where it has the potential to do the most harm


Anaphylaxis1

Anaphylaxis

  • Usually occurs when a specific allergen is injected directly into the circulatory system.

  • The allergen is distributed widely throughout the body.

  • It then interacts with both basophils and mast cells, resulting in massive dumping of histamine.


Anaphylaxis2

Anaphylaxis

  • Principle body systems affected by anaphylaxis are the skin, respiratory system, cardiovascular system, GI system and the nervous system.

  • Histamine causes widespread peripheral vasodilation, as well as increased permeability of the capillaries.


Anaphylaxis3

Anaphylaxis

  • Because of this permeability and the resultant leakage people actually die from circulatory shock.

  • Another substance called slow-reacting substance of anaphylaxis is responsible for the spasms of the bronchioles


Clinical features of anaphylaxis

Clinical Features of Anaphylaxis

  • S&S begin within 30-60 seconds following exposure

  • Severity of reaction is related to the speed of onset of symptoms

  • The faster the reaction the greater the severity

  • Itching and hives are the most common manifestations


Assessment

Assessment

  • Initial assessment: A-B-C

  • Then followed by a detailed assessment


Initial assessment

Initial Assessment

  • Evaluate the airway, most airway problems are associated with laryngeal edema. Take the necessary steps to manage the airway, including intubation or a surgical airway.

  • Evaluate breathing. Rate and depth. Lung sounds. Effort

  • Evaluate circulation. Pulse rate and strength. Blood pressure.


Initial assessment1

Initial Assessment

  • Evaluate neurological status: A-V-P-U


Detailed assessment

Detailed Assessment

  • Concentrate on the skin, the respiratory system, the cardiovascular system and the GI system.

  • Assess for abnormalities and treat as indicated.


Management

Management

  • Airway Management

  • Shock position

  • Maintain body temperature


Fluid and pharmacology

Fluid and Pharmacology

  • Fluid replacement is critical in preventing hypovolemia and hypotension, initiate at least 1 IV of NSS.

  • Principle treatment is pharmacological, which include:

    1.Epinephrine

    2.Antihistamines

    3.Corticosteroids


Epinephrine

Epinephrine

  • Primary medication for anaphylaxis.

  • Reverses the effects of histamine

  • Dose: .3-.5 mg (1:1,000) SQ

  • In severe cases .3-.5 mg (1:10,000) IV


Antihistamines

Antihistamines

  • Second-line agents in anaphylaxis.

  • Block additional histamine from binding with the receptor sites.

  • Dephenhydramine (Benadryl) is the most frequently used antihistamine

  • Dose 25-50 mg slow IV push, or deep IM


Corticosteroids

Corticosteroids

  • Adjunct therapy, to help suppress the inflammatory response associated with anaphylaxis.

  • Most common Methylprednisolone (Solu-Medrol)

  • Dose 125-250 mg, IV or IM


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