1. Paramedic Care: Principles & Practice Volume 4: Medicine CHAPTER Fourth Edition Immunology 5

2. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Multimedia Directory Slide 49Diphenhydramine Animation Slide 58Epinephrine Video

3. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Standard Medicine (Immunology)

4. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Competency Integrates assessment findings with principles of epidemiology and pathophysiology to formulate a field impression and implement a comprehensive treatment/disposition plan for a patient with a medical complaint.

5. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Introduction Allergic reaction: exaggerated response by immune system to foreign substance. –Can range from mild skin rashes to severe, life-threatening reactions that involve virtually every body system.

6. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Introduction Anaphylaxis: most severe type of allergic reaction. –Anaphylaxis is life-threatening emergency; advanced life-support measures often mean difference between life and death.  Can develop within seconds and cause death just minutes after exposure to offending agent.

7. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Introduction Anaphylaxis: most severe type of allergic reaction. –Several emergency medications available that can reverse adverse effects. Injected penicillin and bee and wasp stings two most common causes of fatal anaphylaxis. –400 to 800 deaths annually in U.S. attributed to anaphylaxis.

8. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Principal body system involved in allergic reactions. –Responsible for combating infection. –Components found in blood, bone marrow, lymphatic system. –Goal of immune response: destruction or inactivation of pathogens, abnormal cells, foreign molecules such as toxins.

9. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Cellular immunity: direct attack of foreign substance by specialized cells of immune system. –Humoral immunity: chemical attack of invading substance. –Principal chemical agents of this attack are antibodies (immunoglobulins [Igs]).

10. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Antibodies manufactured by specialized cells of immune system called B cells. –Five classes of antibodies: IgA, IgD, IgE, IgG, IgM. –Humoral immune response begins with exposure of body to antigen. –Antigen: any substance capable of inducing immune response.

11. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Most antigens are proteins. –Following exposure to antigen, antibodies released; attach themselves to invading substance to facilitate removal of that substance from body.

12. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Primary response: initial response to antigen.  Several days required before both cellular and humoral components of immune system respond.

13. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Secondary response: antibodies specific for offending antigen released.  Antigen-specific antibodies more effective.

14. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Natural immunity (innate immunity): genetically predetermined; present at birth; no relation to previous exposure to particular antigen. –Acquired immunity: develops over time; results from exposure to antigen.

15. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Naturally acquired immunity: develops after birth; enhanced by exposure to new pathogens and antigens throughout life. –Induced active immunity (artificially acquired immunity): designed to provide protection from exposure to antigen at some time in future.

16. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Induced active immunity: achieved through vaccination; provides protection against serious infectious agents. –In vaccination, antigen injected into body to generate immune response. –Development of antibodies specific for antigen; provides protection against future infection.

17. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Most vaccines contain antigenic proteins from particular virus or bacterium.  Example: DPT (diphtheria/pertussis/tetanus) vaccine –Some vaccinations will impart lifelong immunity; others periodically followed with “booster dose.”

18. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Acquired immunity is active or passive. –Active immunity: occurs following exposure to antigen; results in production of antibodies specific for antigen. –Most vaccinations result in development of active immunity.

19. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Immune System –Passive immunity: administration of antibodies. –Natural passive immunity: antibodies cross placental barrier from mother to infant to provide protection against embryonic or fetal infections. –Induced passive immunity: administration of antibodies to help fight infection or prevent diseases.

20. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Allergies –Sensitization: initial exposure of individual to antigen; results in immune response.

21. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Allergies –Hypersensitivity: unexpected and exaggerated reaction to particular antigen (allergy).

22. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Allergies –Delayed hypersensitivity: result of cellular immunity; does not involve antibodies; occurs hours and days following exposure. –Immediate hypersensitivity: allergy; immediate reactions: hay fever, drug allergies, food allergies, eczema, asthma.

23. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Allergies –Allergen: antigen that causes release of IgE antibodies.  Drugs  Foods and food additives  Animals  Insects and insect parts  Fungi and molds  Radiology contrast materials

24. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Anaphylactic reactions can result from a variety of causes.

25. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Allergies –Allergens enter body through: oral ingestion, inhalation, topically, injection, or envenomation. –Majority of anaphylactic reactions result from injection or envenomation. –Parenteral penicillin injections most common cause of fatal anaphylactic reactions.

26. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Allergies –Insect stings second most frequent cause of fatal anaphylactic reactions.  Fire ants, wasps, yellow jackets, hornets, honeybees

27. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Allergies –Following exposure to particular allergen, large quantities of IgE antibodies released; attach to membranes of basophils and mast cells.

28. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Allergies –These cells release histamine, heparin, other substances; process of releasing called degranulation. –This release results in allergic reaction; can be mild to severe.

29. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Allergies –Principal chemical mediator of allergic reaction is histamine; minimizes body's exposure to antigen. –Histamine: potent substance; causes bronchoconstriction, increased intestinal motility, vasodilation, increased vascular permeability.

30. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Anaphylaxis –Occurs when specific allergen injected directly into circulation. –When allergen enters circulation, it is distributed widely throughout body. –Principal body systems affected by anaphylaxis: cardiovascular, respiratory, gastrointestinal systems; the skin.

31. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Anaphylaxis –Histamine causes widespread peripheral vasodilation. –Increased permeability of capillaries results in marked loss of plasma from circulation. –People sustaining anaphylaxis can actually die from circulatory shock.

32. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology Anaphylaxis –Released from basophils and mast cells is slow-reacting substance of anaphylaxis (SRS-A).  Results in asthmalike attack; occasionally, asphyxia.

33. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Pathophysiology of anaphylaxis.

34. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Assessment Findings in Anaphylaxis Signs and symptoms begin within 30– 60 seconds following exposure to offending allergen. –Severity often related to speed of onset. –Reactions that develop very quickly tend to be much more severe. Rapid and focused assessment crucial.

35. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Assessment Findings in Anaphylaxis Patients with sense of impending doom often followed by development of additional signs and symptoms. If possible, brief history should be gathered, including previous allergen exposures and reactions. Quickly evaluate level of consciousness.

36. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Assessment Findings in Anaphylaxis Common manifestation is angioneurotic edema, involving face and neck. –Laryngeal edema frequent complication and can threaten the airway. –May lead to complete airway obstruction from either massive laryngeal edema, laryngospasm, pharyngeal edema, or combination of any of these.

37. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Assessment Findings in Anaphylaxis Respiratory system significantly involved in anaphylactic reaction. –Tachypneic; lower airway edema and bronchospasm; respirations become labored; wheezing; markedly diminished lung sounds.

38. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Assessment Findings in Anaphylaxis Fine red rash appears diffusely on skin. Urticaria (hives): wheal and flare reaction characterized by red, raised bumps. As cardiovascular collapse and dyspnea progress, patient will become diaphoretic; if untreated, will progress to cyanosis and pallor.

39. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Hives are red, itchy blotches, sometimes raised, that often accompany an allergic reaction. (© Charles Stewart, MD, MPH)

40. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Assessment Findings in Anaphylaxis Effect of histamine on gastrointestinal system pronounced. –Nausea, vomiting, diarrhea develop. Vital signs vary depending on severity and stage of severe allergic or anaphylactic reaction. –Respiratory rate and heart rate can fall; ominous findings.

41. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Assessment Findings in Anaphylaxis Monitoring devices: cardiac monitor, pulse oximeter; if patient intubated, end-tidal carbon dioxide detector. End-tidal carbon dioxide level may climb due to development of both respiratory and metabolic acidosis.

42. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of Anaphylaxis Ensure scene safe; chemicals or patrolling bees can pose risk. Honeybees often leave stinger behind; if present, remove by scraping skin with fingernail or scalpel blade. Always consider possibility of trauma; signs and symptoms of trauma may be masked by signs and symptoms of anaphylaxis.

43. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of anaphylaxis and allergic reactions.

44. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of Anaphylaxis If suspicion of coincidental trauma, stabilize cervical spine. Position patient and protect airway. Administer oxygen via nonrebreather mask. If patient hypoventilating or apneic, initiate ventilatory assistance. First apply basic airway maneuvers.

45. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of Anaphylaxis Use oropharyngeal and nasopharyngeal airways with caution; can cause laryngospasm If patient having severe airway problems, consider early endotracheal intubation to prevent complete occlusion of airway. Have equipment available for placement of surgical airway.

46. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of Anaphylaxis Establish IV as soon as possible with a crystalloid solution. If patient hypotensive, administer fluids wide open. If time allows, place second IV line.

47. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of Anaphylaxis Administer Medications –Primary treatment for anaphylaxis is pharmacological. –Oxygen always first drug to administer with anaphylactic reaction. –Epinephrine primary drug for use in treatment of severe allergic reactions and anaphylaxis; sympathetic agonist.  Acts within minutes of administration.

48. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of Anaphylaxis Administer Medications –Antihistamines second-line agents in treatment of anaphylaxis; given only following administration of epinephrine.  Block effects of histamine by blocking histamine receptors.  Diphenhydramine (Benadryl): most frequently used antihistamine in treatment of allergic reactions and anaphylaxis.

49. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Diphenhydramine Animation Click here to view an animation on the topic of diphenhydramine.here Back to Directory

50. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of Anaphylaxis Administer Medications –Corticosteroids: important in treatment and prevention of anaphylaxis; help suppress inflammatory response. –Vasopressors: severe and prolonged anaphylactic reactions may require potent vasopressors to support blood pressure.  Dopamine, norepinephrine, epinephrine

51. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of Anaphylaxis Administer Medications –Beta-agonists: severe allergic reactions and anaphylaxis will develop bronchospasm, laryngeal edema, or both.  Prehospital care: albuterol (Ventolin, Proventil).  Reverse some of bronchospasm and laryngeal edema associated with anaphylaxis.

52. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of Anaphylaxis Administer Medications –Other Agents: vasopressin, atropine, glucagon. –Provide patient emotional support and explain treatment regimen. –Caution patients about potential side effects of administered medications.

53. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Assessment Findings in Allergic Reaction Allergic reaction will have more gradual onset with milder signs and symptoms. Patient will have normal mental status.

54. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of Allergic Reactions Mild (nonanaphylactic) allergic reactions: itching, rash, urticaria. –Simple itching and nonurticarial rashes treated with antihistamines alone. –In addition to antihistamines, epinephrine often necessary for treatment of urticaria. If exhibits dyspnea or wheezing, should receive supplemental oxygen.

55. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Management of Allergic Reactions Lesser allergic reactions not accompanied by hypotension or airway problems treated with epinephrine 1:1,000 administered intramuscularly. –Intramuscular route should not be used in severe anaphylaxis; IV epinephrine should be administered.

56. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Patient Education Many severe allergic and anaphylactic reactions preventable. Persons with history of anaphylactic reactions should be educated about recognition and treatment. They should wear identification device, such as Medic-Alert bracelet; alerts paramedics to condition if they are unresponsive.

57. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Patient Education Many patients initiate emergency anaphylactic treatment at home with epinephrine delivery systems (EpiPen). Severity of allergic reaction can be diminished in certain cases through process called desensitization. –Quantity of allergen in injection gradually increased to point where anaphylactic reactions are averted.

58. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Epinephrine Video Click here to view a video on the topic of administration of epinephrine by auto- injector.here Back to Directory

59. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Patient Education Paramedics often keep reference cards for anaphylactic patients living in their service area. –Quickly identify them, their allergy, prehospital treatment history.

60. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Summary Severe allergies and anaphylaxis uncommon. When they do occur, they can progress quickly and result in death in minutes.

61. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Summary Central physiologic action in anaphylaxis is massive release of histamine and other mediators. Histamine causes bronchospasm, airway edema, peripheral vasodilation, and increased capillary permeability.

62. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Summary Primary, and most important, drug used in treatment of anaphylaxis is epinephrine. Epinephrine helps reverse effects of histamine.

63. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Summary Epinephrine also supports blood pressure and reverses detrimental capillary leakage. Following administration of epinephrine, potent antihistamines should be used to block adverse effects of massive histamine release.

64. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Summary Inhaled beta-agonists useful in severe bronchospasm and airway involvement. Intravenous fluid replacement crucial in preventing hypovolemia and hypotension.

65. ©2013 Pearson Education, Inc. Paramedic Care: Principles & Practice, 4 th Ed. Summary Key to successful prehospital management of anaphylaxis is prompt recognition and treatment.