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Allergic Reactions and Anaphylaxis

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									Allergic Reactions &
    Anaphylaxis

    EMS Professions
     Temple College
                   Incidence
   In USA - 400 to 800 deaths/year
   Parenterally administered penicillin accounts
    for 100 to 500 deaths per year
   Hymenoptera stings account for 40 to 100
    deaths per year
   Risk factors: beta-blockers, adrenal
    insufficiency
            Causes of Deaths
   Laryngeal edema and acute bronchospasm
    with respiratory failure account for >70%
   Circulatory collapse accounts for 25%
   Other <5% - ?brain ?MI
             Allergic Reaction
    Physiologic response to antigens
    – Oversensitive response = allergic
    – Occurs after sensitization to antigen
   Antigen binds with Antibody
    – Less severe result in inflammatory response
    – Type I reaction involves antibodies attached to mast
      cells or basophils = most severe form
                Anaphylaxis
   Systemic reaction of multiple organ systems to
    antigen-induced IgE-mediated immunulogic
    mediator release in previously sensitized
    individual
              Allergic Reaction
   Antigen
    – Induces antibody formation
    – Examples
      » Drugs (antibiotics)
      » Foods (nuts, shellfish)
      » Insect venoms
      » Animal serum
      » Incompatible blood types
                     Anaphylaxis
   Antigens enter body by:
    –   Injection
    –   Ingestion
    –   Inhalation
    –   Absorption
     Anaphylaxis Pathophysiology
   Antigen enters body
   Antibodies produced
   Attach to surface of mast or basophil cells
   Mast cells become sensitized
    Anaphylaxis Pathophysiology
   Mast cells
    – In all subcutaneous/submucosal tissues,
    – Including conjunctiva, upper/lower respiratory
      tracts, and gut
   Basophils
    – Circulate in blood
     Anaphylaxis Pathophysiology
   Antigen reenters body
   Attaches to antibodies on mast or basophil cells
   Mast cell degranulates, releases
    –   Histamine
    –   Leukotrienes
    –   Slow reacting substance of anaphylaxis (SRS-A)
    –   Eosinophil chemotactic factor (ECF)
                Histamine
   Three histamine receptor types:
    – H1
    – H2
    – H3
                 Histamine
   Acts on H1 receptors to cause
    – Smooth muscle contraction
    – Increased vascular permeability
    – Prostaglandin generation
                   Histamine
   Acts on H2 receptors to cause
    –   Increased vascular permeability
    –   Gastric acid secretion
    –   Stimulation of suppressor lymphocytes
    –   Decreased PMN enzyme release
    –   Release of more histamine from mast cells
        and basophils
                 Histamine
   Acts on H3 receptors to cause
    – Inhibition of central, peripheral nervous
      system neurotransmitter release
    – Inhibition of further histamine formation,
      release
                Vasodilation
   Decreased peripheral vascular resistance
   Hypotension
   Tachycardia
   Peripheral hypoperfusion
    Increased Capillary Permeability
   Tissue edema, urticaria (hives), itching
   Laryngeal edema
    – Airway obstruction
    – Respiratory distress
    – Stridor
   Fluid leakage from vascular space
    – Hypovolemic shock
Urticaria
          Smooth Muscle Spasm
   Bronchospasm                Bladder Spasm
    – Respiratory distress       – Urinary urgency
    – “Tight Chest”              – Urinary incontinence
    – Wheezing
   GI Tract Spasm
    – Nausea, vomiting
    – Cramping, diarrhea
       Anaphylactic Reaction
   Leukotrienes
    – Potent bronchoconstrictors,  vascular
      permeability & possibly coronary
      vasoconstriction
    – Slower onset than histamine
    – Effects last longer than histamine
          Allergic Reactions
   Generally classified into 3 groups:
    – Mild allergic reaction
    – Moderate allergic reaction
    – Severe allergic reaction (anaphylaxis)
          Mild Allergic Reaction
   Characteristics
    –   Urticaria (hives), itchy
    –   Erythema (redness)
    –   Rhinitis
    –   Conjunctivitis
    –   Mild bronchoconstriction
    –   Usually localized (look on abdomen, chest, back)
   No SOB or hypotension/hypoperfusion
   Often self-treated at home
      Moderate Allergic Reaction
   Characteristics
    – Mild signs/symptoms with any of following:
       » Dyspnea, possibly with wheezes
       » Angioneurotic edema
       » Systemic, not localized
   No hypotension/hypoperfusion
        Severe Allergic Reaction
             (Anaphylaxis)
   Characteristics
    – Mild and/or moderate signs/symptoms plus
    – Shock / hypoperfusion
          Clinical Manifestation
   Dependent on:
    –   Degree of hypersensitivity
    –   Quantity, route, rate of antigen exposure
    –   Pattern of mediator release
    –   Target organ sensitivity and responsiveness
         Clinical Manifestation
   Severity varies from mild to fatal
   Most reactions are respiratory, dermatologic
   Less severe early findings may progress to life-
    threatening over a short time
   Initial signs/symptoms do NOT necessarily
    correlate with severity, progression, duration of
    response
   Generally, quicker symptoms = more severe
    reactions
        Clinical Manifestation
   First manifestations involve skin
    – Warmth and tingling of the face, mouth,
      upper chest, palms and/or soles, or site of
      exposure
    – Erythema
    – Pruritus is universal feature, erythema
    – May be accompanied by generalized
      flushing, urticaria, nonpruritic angioedema
           Clinical Manifestation
   May progress to involvement of respiratory
    system
    –   cough
    –   chest tightness
    –   dyspnea
    –   wheezing
    –   throat tightness
    –   dysphagia
    –   hoarseness
        Clinical Manifestation
   Other Signs and Symptoms
    – lightheadedness or syncope caused by
        hypotension or dysrhythmia
    – nasal congestion and sneezing
    – ocular itching and tearing
    – cramping abdominal pain with nausea,vomiting, or
      diarrhea
    – bowel or bladder incontinence
    – decreased level of consciousness
         Clinical Manifestation
   Physical Exam findings may include
    – urticaria, angioedema, rhinitis, conjunctivitis
    – tachypnea, tachycardia, hypotension
    – laryngeal stridor, hypersalivation, hoarseness,
      angioedema
    Insect Sting Hypersensitivity
   Hymenoptera - yellow jackets, honeybees,
    hornets, wasps, bumble bees
   90%: Local hives, pruritus
   10%: Massive local reaction, including
    swelling beyond two joints of extremity
   1%: Systemic reaction
   10%: have worse reaction on second sting
   28%: have recurrent systemic reaction
             Management
   Treatment depends upon severity of
    reaction and signs/symptoms of its
    presentation
                   Management
   Optimal management requires
    –   High index of suspicion (suspect, treat within minutes)
    –   Early diagnosis
    –   Pharmaceutical intervention
    –   Observation
    –   Disposition
      Patient Self-Management
   Benadryl 50 mg p.o.
   At any sign of anaphylaxis, self-administer
    subcutaneous epinephrine (Epi-Pen®, Ana-
    Kit®)
   If short of breath or wheezing, use aerosolized
    epinephrine (Primatene Mist, Medihaler-Epi)
         Mild Allergic Reaction
   Often self-treated at home
   Diphenhydramine 25 - 50mg PO or IM
    – IV is acceptable but should include transport
   If stinger present, flick it away with credit card
    or fingernail
   May consider (if available and indicated):
    – cimetidine or ranitidine
    – prednisone
    – inhaled beta-agonists
      Moderate Allergic Reaction
   High flow oxygen
   IV NS
    – Titrated to systolic BP 90 mm Hg
   ECG monitor
   Beta agonists
    – Nebulized albuterol, isoetharine, terbutaline
    – SQ terbutaline or epinephrine 1:1000 or IV aminophylline if
      severe bronchoconstriction
   Diphenhydramine 25-50 mg IM or IV
   Methylprednisolone 125 mg IV
   Transport
                     Anaphylaxis
   Airway and Breathing
    – High concentration oxygen
    – Ventilations, ETT, alternative airway prn
    – Consider inhaled beta agonists
   Circulation
    – Large bore IV NS X 2
    – Quickly titrate fluids to perfusion with bolus therapy
    – ECG monitor
   Treat as pre-arrest patient
                  Anaphylaxis
   Epinephrine 0.5 - 1.0 mg 1:10,000 IV prn
    – Hypotension unresponsive to fluids and epinephrine
       consider dopamine ~10 mcg/kg/min
    – Bronconstriction unresponsive to Epi  consider
      aminophylline
   Diphenhydramine 50 mg IV
   Methylprednisolone 125 mg IV
   Consider MAST if unresponsive to fluids
   Rapid transport
                Disposition
   Regardless of response to therapy, all
    patients with systemic features must be
    observed for 6 to 8 hours
             Latex Allergies
   Due to a growing number of persons
    experiencing latex allergies, EMS
    providers should be prepared to
    treat patients with such allergies
    – Have latex free equipment
    – Use the patient’s latex free supplies
           Case Presentation #1
   You are dispatched to an electronics manufacturing
    plant to see a 28-year-old woman. The woman believes
    she is having an allergic reaction. Security officers will
    meet you at the front gate and escort you to the patient.



       What specific information would you like
                     at this point?
           Case Presentation #1
   You find this patient in an office area sitting at her
    desk. From a distance, you notice she is awake and
    speaking clearly. She does not appear to have any
    breathing difficulty. She states she had just returned
    from lunch and began to feel hot and light headed. Her
    friend pointed out that the patient’s arms and neck are
    very red, and that her face appears “puffy”.
            Case Presentation #1
    The patient states she is allergic to peanuts but has not
     eaten any. She went to a health food café where she
     had grilled chicken and steamed vegetables. She has no
     other past history and takes no medications. Her last
     allergic rx was similar to this. Vitals are: BP-116/70;
     Pulse-100; RR-20; Lung sounds-clear and equal. No
     difficulty swallowing, redness to her arms, chest, neck
     and face.

Would you like to perform any other procedures/exams/testing
          or obtain other history before treating?
     Case Presentation #1

So, what is your complete treatment plan
             for this patient?
           Case Presentation #2
   39 year-old male found at home in respiratory arrest
    with a bradycardic carotid pulse. His wife states he
    was helping a friend paint when he was apparently
    stung by a bee. He walked into the house, saying “I
    don’t feel good,” and collapsed.
            Case Presentation #2
   PMH: depression, gastritis, seasonal allergies
   Medications: Ritalin, Zantac, Prozac, Claritin
   No known drug allergies
   No prior reactions to hymenoptera



    What therapies would you like to begin for this man?
           Case Presentation #2

   You have done the following:
     – intubated orotracheally
     – administered intravenous epinephrine, 0.5 mg &
       diphenhydramine 50 mg
     – started 2 large-bore IVs of NS and given 500 cc fluid
   At this point, the patient no longer has a pulse
           Case Presentation #2
   You begin CPR and give the following:
     – Dopamine drip at 10 mcg/kg/min
     – Epinephrine, 1:10,000, 1 mg IV q 3-5 min
   You now note the following:
     – ECG: Idioventricular rhythm
     – Lung Sounds: difficult to hear
     – Obvious facial edema


     Can you think of any ideas for further treatment?

								
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