Transcript Anaphylaxis & Allergy NSC - Hatzalah of Miami-Dade

Allergic Reactions &
Anaphylaxis
Incidence
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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
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Laryngeal edema and acute bronchospasm
with respiratory failure account for >70%
Circulatory collapse accounts for 25%
Other <5% - ?brain ?MI
Allergic Reaction
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 Physiologic response to antigens
– Oversensitive response = allergic
– Occurs after sensitization to antigen
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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
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Systemic reaction of multiple organ systems to
antigen-induced IgE-mediated immunulogic
mediator release in previously sensitized
individual
Allergic Reaction
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Antigen
– Induces antibody formation
– Examples
» Drugs (antibiotics)
» Foods (nuts, shellfish)
» Insect venoms
» Animal serum
» Incompatible blood types
Anaphylaxis
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Antigens enter body by:
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Injection
Ingestion
Inhalation
Absorption
Anaphylaxis Pathophysiology
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Antigen enters body
Antibodies produced
Attach to surface of mast or basophil cells
Mast cells become sensitized
Anaphylaxis Pathophysiology
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Mast cells
– In all subcutaneous/submucosal tissues,
– Including conjunctiva, upper/lower respiratory
tracts, and gut
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Basophils
– Circulate in blood
Anaphylaxis Pathophysiology
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Antigen reenters body
Attaches to antibodies on mast or basophil cells
Mast cell degranulates, releases
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Histamine
Leukotrienes
Slow reacting substance of anaphylaxis (SRS-A)
Eosinophil chemotactic factor (ECF)
Histamine
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Three histamine receptor types:
– H1
– H2
– H3
Histamine
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Acts on H1 receptors to cause
– Smooth muscle contraction
– Increased vascular permeability
– Prostaglandin generation
Histamine
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Acts on H2 receptors to cause
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Increased vascular permeability
Gastric acid secretion
Stimulation of suppressor lymphocytes
Decreased PMN enzyme release
Release of more histamine from mast cells
and basophils
Histamine
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Acts on H3 receptors to cause
– Inhibition of central, peripheral nervous
system neurotransmitter release
– Inhibition of further histamine formation,
release
Vasodilation
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Decreased peripheral vascular resistance
Hypotension
Tachycardia
Peripheral hypoperfusion
Increased Capillary Permeability
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Tissue edema, urticaria (hives), itching
Laryngeal edema
– Airway obstruction
– Respiratory distress
– Stridor
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Fluid leakage from vascular space
– Hypovolemic shock
Urticaria
Smooth Muscle Spasm
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Bronchospasm
– Respiratory distress
– “Tight Chest”
– Wheezing
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GI Tract Spasm
– Nausea, vomiting
– Cramping, diarrhea
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Bladder Spasm
– Urinary urgency
– Urinary incontinence
Anaphylactic Reaction
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Leukotrienes
– Potent bronchoconstrictors,  vascular
permeability & possibly coronary
vasoconstriction
– Slower onset than histamine
– Effects last longer than histamine
Allergic Reactions
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Generally classified into 3 groups:
– Mild allergic reaction
– Moderate allergic reaction
– Severe allergic reaction (anaphylaxis)
Mild Allergic Reaction
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Characteristics
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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
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Characteristics
– Mild signs/symptoms with any of following:
» Dyspnea, possibly with wheezes
» Angioneurotic edema
» Systemic, not localized
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No hypotension/hypoperfusion
Severe Allergic Reaction
(Anaphylaxis)
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Characteristics
– Mild and/or moderate signs/symptoms plus
– Shock / hypoperfusion
Clinical Manifestation
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Dependent on:
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Degree of hypersensitivity
Quantity, route, rate of antigen exposure
Pattern of mediator release
Target organ sensitivity and responsiveness
Clinical Manifestation
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Severity varies from mild to fatal
Most reactions are respiratory, dermatologic
Less severe early findings may progress to lifethreatening 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
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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
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May progress to involvement of respiratory
system
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cough
chest tightness
dyspnea
wheezing
throat tightness
dysphagia
hoarseness
Clinical Manifestation
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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
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Physical Exam findings may include
– urticaria, angioedema, rhinitis, conjunctivitis
– tachypnea, tachycardia, hypotension
– laryngeal stridor, hypersalivation, hoarseness,
angioedema
Insect Sting Hypersensitivity
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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
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Treatment depends upon severity of
reaction and signs/symptoms of its
presentation
Management
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Optimal management requires
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High index of suspicion (suspect, treat within minutes)
Early diagnosis
Pharmaceutical intervention
Observation
Disposition
Patient Self-Management
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Benadryl 50 mg p.o.
At any sign of anaphylaxis, self-administer
subcutaneous epinephrine (Epi-Pen®, AnaKit®)
If short of breath or wheezing, use aerosolized
epinephrine (Primatene Mist, Medihaler-Epi)
Mild Allergic Reaction
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Often self-treated at home
Diphenhydramine 25 - 50mg PO or IM
– IV is acceptable but should include transport
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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
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High flow oxygen
IV NS
– Titrated to systolic BP 90 mm Hg
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ECG monitor
Beta agonists
– Nebulized albuterol, isoetharine, terbutaline
– SQ terbutaline or epinephrine 1:1000 or IV aminophylline if severe
bronchoconstriction
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Diphenhydramine 25-50 mg IM or IV
Methylprednisolone 125 mg IV
Transport
Anaphylaxis
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Airway and Breathing
– High concentration oxygen
– Ventilations, ETT, alternative airway prn
– Consider inhaled beta agonists
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Circulation
– Large bore IV NS X 2
– Quickly titrate fluids to perfusion with bolus therapy
– ECG monitor
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Treat as pre-arrest patient
Anaphylaxis
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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
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Diphenhydramine 50 mg IV
Methylprednisolone 125 mg IV
Consider MAST if unresponsive to fluids
Rapid transport
Disposition
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Regardless of response to therapy, all
patients with systemic features must be
observed for 6 to 8 hours
Latex Allergies
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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
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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
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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
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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
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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
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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
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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
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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?