anaphylaxis & allergy nsc
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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– Respiratory distress
– “Tight Chest”
– Wheezing GI Tract Spasm
– Nausea, vomiting
– Cramping, diarrhea
Bladder Spasm– Urinary urgency
– Urinary incontinence
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 likeat 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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