01 allergies and anaphylaxis


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01 allergies and anaphylaxis

  1. 1. Allergies / Anaphylaxis Dutchess Community College EMS
  2. 2. Sections Anatomy Review Pathophysiology Assessment Findings in Anaphylaxis Management of Anaphylaxis Assessment Findings in Allergic Reaction Management of Allergic Reactions Patient Education Dutchess Community College EMS
  3. 3. Allergies, Anaphylaxis, and Anaphylactoid Reactions Allergic Reaction  An exaggerated response by the immune system to a foreign substance Anaphylaxis An unusual or exaggerated allergic reaction  A life-threatening emergency  Anaphylactoid reaction* does not involve IgE antibody mediation.  May occur without previous exposure  Patient presentation is the same.  Dutchess Community College EMS
  4. 4. Pathophysiology The Immune System Pathogens  Toxins  Cellular Immunity  Humoral Immunity   Antibodies (Immunoglobulins)  IgA, IgD, IgE, IgG, IgM Dutchess Community College EMS
  5. 5. Antigens and Immunogens Antigens that are able to trigger the immune response are immunogens. Not every antigen can trigger an immune response. Dutchess Community College EMS
  6. 6. Characteristics of Antigenic Immunogenicity Sufficient foreignness. Sufficient size. Sufficient complexity. Presence in sufficient amounts. Dutchess Community College EMS
  7. 7. Primary vs. Secondary Immune Responses Primary immune response is the initial development of antibodies in response to the first exposure to an antigen. Secondary immune response is the swift, strong response of the immune system to repeated exposures to an antigen. Dutchess Community College EMS
  8. 8. Humoral vs. Cell-mediated Immunity Humoral immunity is the long-term immunity to an antigen provided by antibodies produced by B lymphocytes. Cell-mediated immunity is short term immunity to an antigen provided by T lymphocytes. Dutchess Community College EMS
  9. 9. B Lymphocytes White blood cells. Respond to antigens and produce antibodies that attack the antigen. Develop a memory for the antigen. Confer long-term immunity to specific antigens. Dutchess Community College EMS
  10. 10. T Lymphocytes White blood cells. Do not produce antibodies. Recognize the presence of a foreign antigen and attacks it directly. Dutchess Community College EMS
  11. 11. Humoral Immune Response Long-lasting response provided by production in the bloodstream of antibodies and memory cells called B lymphocytes. This is also called the internal or systemic immune system. Dutchess Community College EMS
  12. 12. Humoral Immune Response Dutchess Community College EMS
  13. 13. CellMediated Immune Response Dutchess Community College EMS
  14. 14. Lymphocytes Lymphocytes are generated from stem cells in the bone marrow. These take one of two paths as they mature. Through the thymus gland and mature into T lymphocytes.  Through a set of lymphoid tissues and mature into B lymphocytes.  Dutchess Community College EMS
  15. 15. B cells specialize through process of clonal diversity and clonal selection. Dutchess Community College EMS
  16. 16. B Cells Clonal diversity is generated as the precursors of mature B cells develop in the bone marrow. The B cell precursor develops receptors for every possible type of antigen it may encounter. Dutchess Community College EMS
  17. 17. Pathophysiology Immune Response    Exposure to antigen produces primary response with general antibodies. Immune system develops antigen-specific antibodies and memory. Future exposures generate a faster secondary response. Induced Active Immunity Active and Passive Immunity Dutchess Community College EMS
  18. 18. Natural vs. Acquired Immunity Natural immunity is part of genetic makeup. Acquired immunity develops as an outcome of the immune response: Active immunity is generated by the immune system after exposure to an antigen;  Passive immunity is transferred to a person from an outside source.  Dutchess Community College EMS
  19. 19. Antigen-antibody binding. The shape of the antigen fits the shape of the antigen-binding site on the immunoglobulin (antibody) molecule like a key in a lock. Dutchess Community College EMS
  20. 20. The Functions of Antibodies An antibody circulates in the blood or is suspended in body secretions until it meets and binds to a specific antigen. Antigen-antibody complexes form from the direct and indirect binding of antibodies and antigens. Dutchess Community College EMS
  21. 21. Direct Effects of Antibodies on Antigens Dutchess Community College EMS
  22. 22. Agglutination A soluble antibody combines with a solid antigen causing it to clump together. Dutchess Community College EMS
  23. 23. Precipitation The antigen-antibody complex precipitates out of the blood and is carried away by body fluids. Dutchess Community College EMS
  24. 24. Neutralization The antibody, in combining with the antigen, inactivates the antigen by preventing it from binding to receptors on the surface of cells. Dutchess Community College EMS
  25. 25. Indirect Effects of Antibodies on Antigens Dutchess Community College EMS
  26. 26. Enhancement of Phagocytosis Phagocytosis is one of the chief processes of inflammation in which certain types of white blood cells ingest and digest foreign substances. Dutchess Community College EMS
  27. 27. Activation of Plasma Proteins Antibodies can activate plasma proteins of the complement system that attack and destroy antigens. Dutchess Community College EMS
  28. 28. Functions of Antibodies Neutralization of bacterial toxins. Neutralization of viruses. Opsonization of bacteria. Activation of the inflammatory processes. Dutchess Community College EMS
  29. 29. Classes of Immunoglobulins IgM—produced first. IgG—has “memory.” IgA—involved in secretory immune responses. IgE—involved in allergic reactions. IgD—present in very low concentrations. Dutchess Community College EMS
  30. 30. Human Antibody Classifications Isotypic - same with same species. Allotypic - differ between members of same species. Idiopathic - differ within the same individual. Dutchess Community College EMS
  31. 31. Secretory Immune System Primary function is to protect the body from pathogens that are inhaled or ingested. Dutchess Community College EMS
  32. 32. Cell-Mediated Immune Response Dutchess Community College EMS
  33. 33. Types of Mature T Cells Memory cells—secondary immune responses. Td cells—delayed hypersensitivity. Tc cells—cytotoxic. Th cells—helpers. Ts cells—suppressors. Dutchess Community College EMS
  34. 34. The Physiology of Cytotoxic T cells. Dutchess Community College EMS
  35. 35. Cellular Interactions in Immune Response Antigen-presenting (macrophages) interact with Th (helper) cells. Th (helper) cells interact with B cells. Th (helper) cells interact with Tc (cytotoxic) cells. Dutchess Community College EMS
  36. 36. Cytokines Messengers of the immune response. Help regulate cell functions during the inflammatory and immune functions. Monokines are released by a macrophage. Lymphokines are released by a lymphocyte. Dutchess Community College EMS
  37. 37. Processes Necessary For Immune Response Antigen processing (by macrophages). Antigen presentation (by macrophages). Antigen recognition (by T cells or B cells). Dutchess Community College EMS
  38. 38. Antigen Processing The recognition, ingestion, and breakdown of a foreign antigen. Dutchess Community College EMS
  39. 39. Antigen Presentation Following antigen processing, antigen fragments are expressed by the macrophage and presented on its surface with its own antigens. Dutchess Community College EMS
  40. 40. Antigen Recognition Helper T cells recognize foreign and self antigens and the helper T cells are activated. Dutchess Community College EMS
  41. 41. Fetal and Neonatal Immune Function Some immune response capabilities are developed in utero, but most of the immune response system is not fully developed. Dutchess Community College EMS
  42. 42. Fetal and Neonatal Immune Function To protect the child in utero and during the first few months after birth, maternal antibodies cross the placenta into the fetal circulation. Trophoblasts actively transport immunoglobulin cells from fetal to maternal circulation. At birth antibodies begin to drop until the immune system matures. Dutchess Community College EMS
  43. 43. Aging and the Immune Response As the human body ages, immune functions begin to deteriorate. T cells are primarily affected. Dutchess Community College EMS
  44. 44. Allergies Sensitization Hypersensitivity  Delayed     Results from cellular immunity and does not involve antibodies. Commonly results in skin rash. Results from exposure to certain drugs or chemicals. Immediate   Exposure quickly results in secondary response. More severe than delayed hypersensitivity. Dutchess Community College EMS
  45. 45. Allergies Allergen  Exposure generates secondary response. Large quantities of IgE are released.  Allergen binds to IgE, causing chemical release.      Release is “allergic reaction.” Includes histamines, heparin, and other substances that are designed to minimize the body’s exposure to an antigen. Histamine causes bronchoconstriction, vasodilation, increased gastric motility, and increased vascular permeability. Angioneurotic edema. Dutchess Community College EMS
  46. 46. Anaphylaxis Dutchess Community College EMS
  47. 47. Anaphylaxis Causes  Injections Most anaphylaxis results from the injected route.  Allergen rapidly distributed throughout the body, resulting in massive histamine release.      Parenteral penicillin injections and insect stings. Affects cardiovascular, respiratory, gastrointestinal, and integumentary systems. Significant plasma loss through increased vascular permeability. Slow-reacting substance of anaphylaxis. Dutchess Community College EMS
  48. 48. Assessment Findings in Anaphylaxis Focused History & Physical Exam  Focused History  SAMPLE & OPQRST History     Rapid onset, usually 30–60 seconds following exposure. Speed of reaction is indicative of severity. Previous allergies and reactions. Physical Exam  Presence of severe respiratory difficulty is key to differentiating anaphylaxis from allergic reaction. Dutchess Community College EMS
  49. 49. Assessment Findings in Anaphylaxis  Physical Exam      Facial or laryngeal edema Abnormal breath sounds Hives and urticaria Hyperactive bowel sounds Vital sign deterioration as the reaction progresses Dutchess Community College EMS
  50. 50. Management of Anaphylaxis Scene Safety  Consider the possibility of trauma. Protect the Airway. Use airway adjuncts with care.  Intubate early in severe cases to prevent total occlusion of the airway.  Be prepared to place a surgical airway.  Dutchess Community College EMS
  51. 51. Management of Anaphylaxis Support Breathing  High-flow oxygen or assisted ventilation if indicated. Establish IV Access  Patient may be volume-depleted due to “third spacing” of fluid. Administer crystalloid solution at appropriate rate.  Place a second IV line if indicated.  Dutchess Community College EMS
  52. 52. Management of Anaphylaxis Administer Medications:        Oxygen Epinephrine Antihistamines Corticosteroids Vasopressors Beta-agonists Other agents Psychological Support Dutchess Community College EMS
  53. 53. Assessment Findings in Allergic Reaction Dutchess Community College EMS
  54. 54. Management of Allergic Reactions Scene safety Protect the airway. Support breathing. Establish IV access. Administer medications:   Antihistamines Epinephrine Dutchess Community College EMS
  55. 55. Patient Education Prevention of Reactions Recognition of Signs/Symptoms  Patient-initiated treatment  Epinephrine auto-injectors Desensitization Dutchess Community College EMS
  56. 56. Variances in Immunity Dutchess Community College EMS
  57. 57. Types of Hypersensitivity Allergy Autoimmunity Isoimmunity Dutchess Community College EMS
  58. 58. Mechanisms of Hypersensitivity Reaction Type I: IgE-mediated allergen reactions. Type II: tissue-specific reactions. Type III: immune complex- mediated reactions. Type IV: cell-mediated reactions. Dutchess Community College EMS
  59. 59. Type I- IgE Reactions Upon re-exposure to an allergen, the allergen binds to the IgE on the mast cell. Degranulation of the mast cell occurs. Histamine is released. The inflammatory response is triggered. Dutchess Community College EMS
  60. 60. Clinical Indications of IgE Mediated Responses Skin—flushed, itching, hives, edema. Respiratory system—breathing difficulty, laryngeal edema, laryngospasm, bronchospasm. Cardiovascular system—vasodilation and permeability, increased heart rate, increased blood pressure. Dutchess Community College EMS
  61. 61. Clinical Indications of IgE Mediated Responses GI system—nausea, vomiting, cramping, diarrhea. Nervous system—dizziness, headache, convulsions, tearing. Dutchess Community College EMS
  62. 62. Type II—Tissue-Specific Reactions An immune response against some antigens present on only some body tissues. Dutchess Community College EMS
  63. 63. Type III—Immune ComplexMediated Reactions (1 of 3) • Results from antigen-antibody complexes that are formed when antibodies circulating in the blood or suspended in body secretions meet and bind to a specific antigen. Dutchess Community College EMS
  64. 64. Type III- Immune Complex-Mediated Reactions (2 of 3) • The organ affected has very little connection with where or how the antigen or the immune complex originated. Dutchess Community College EMS
  65. 65. Type III - Immune Complex-Mediated Reactions (3 of 3) • Systemic immune complex diseases are called serum sickness:  Renaud’s Disease. • Local immune complex diseases are arthrus reactions: Skin reactions following inoculation.  GI reaction to wheat products.  Dutchess Community College EMS
  66. 66. Type IV- Cell Mediated Tissue Reactions • Activated directly by T cells, and do not involve antibody. • Examples: graft rejection, contact allergic reaction—poison ivy. Dutchess Community College EMS
  67. 67. Targets of Hypersensitivity Type of Hypersensitivity Targeted Antigen Allergy Environmental antigens Autoimmunity Self antigens Isoimmunity Other person’s antigens Dutchess Community College EMS
  68. 68. Autoimmune and Isoimmune Diseases • • • • Grave’s disease Rheumatoid arthritis Myasthenia gravis Immune thrombocytopenia purpura • • • Isoimmune neutropenia Systemic lupus erhthyematosus Rh and ABO isoimmunization Dutchess Community College EMS
  69. 69. Deficiencies in Immunity Dutchess Community College EMS
  70. 70. Congenital Immune Deficiencies Develops if the development of lymphocytes in the fetus or embryo is impaired or halted: • DiGeorge syndrome • Bruton agammaglobulinemia • Bare lymphocyte syndrome • Wiskott-Aldrich syndrome • Selective IaG deficiency • Chronic mucocutaneous candidiasis Dutchess Community College EMS
  71. 71. Acquired Immune Deficiencies • Nutritional deficiencies • Latrogenic deficiencies • Deficiencies caused by trauma • Deficiencies caused by stress • AIDS Dutchess Community College EMS
  72. 72. Replacement Therapies for Immune Deficiencies • Gamma globulin therapy • Transplantation and transfusion • Gene therapy Dutchess Community College EMS
  73. 73. Summary • Pathophysiology • Assessment Findings in Anaphylaxis • Management of Anaphylaxis • Assessment Findings in Allergic Reaction • Management of Allergic Reactions • Patient Education Dutchess Community College EMS