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ANAPHYLAXIS

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

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  1. ANAPHYLAXIS

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. Allergies • Hypersensitivity is often used synonymously with the term allergy. • Two types of hypersensitivity reactions: 1. Delayed 2. Immediate

  16. 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

  17. 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

  18. 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.

  19. 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

  20. 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.

  21. 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

  22. 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

  23. 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

  24. 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.

  25. 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.

  26. 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

  27. 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

  28. Assessment • Initial assessment: A-B-C • Then followed by a detailed assessment

  29. 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.

  30. Initial Assessment • Evaluate neurological status: A-V-P-U

  31. Detailed Assessment • Concentrate on the skin, the respiratory system, the cardiovascular system and the GI system. • Assess for abnormalities and treat as indicated.

  32. Management • Airway Management • Shock position • Maintain body temperature

  33. 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

  34. 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

  35. 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

  36. 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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