Anaphylaxis

1
Anaphylaxis

• Michael Kenney CCFP(EM)

2
Outline

• Case-based
• Clinical features
• DDx
• High risk patients
• Biphasic reaction
• Focus on management
• Highlight specific aspects
• Airway
• Shock
• Disposition

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Significance

• Common
• 1 fatal
• Wide spectrum of presentation
• Mild - life-threatening
• Identify the impending disaster
• Affects young people
• Good outcomes expected
• Deterioration can be sudden
• Must have management strategies firmly embedded

4
Case

• 36f generalized urticarial rash 2h ago

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Definition

• Poorly defined
• Clinical definition
• Severe, potentially life-threatening, multisystem
  allergic response
• more than one system
• Cutaneous
• Respiratory
• Cardiovascular
• GI manifestations

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Pathophys Basics

• IgE mediated
• Mast cell/basophil degranulation
• Sensitization required
• H1 and H2 receptors (H7)
• Smooth muscle contraction
• Capillary leakage
• Mucosal edema/mucus production
• Vasodilation

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Clinical Manifestations?
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Clinical Manifestations

• Cutaneous 90
• Urticaria, angioedema, flushing
• pruritis alone
• Respiratory 55
• Wheeze
• UA angioedema
• Near syncope, hypotension 35
• GI 30
• Nausea, vomiting, diarrhea
• Cramping common

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Clinical Manifestations

• 5-60 minutes
• Most fatalities within 30min
• Parenteral 5-30min
• Oral route up to 2 hours
• Mild Sx to impending catastrophe within minutes

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Why do patients die?
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Critical Care

• Airway
• Significant angioedema
• Hoarse voice
• Stridor
• Breathing
• Aggressive management of bronchospasm
• Circulation
• Shock

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Causes?

• _at_ 35 remain unidentified

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Causes

• Foods
• Peanuts
• Crustaceans
• Drugs
• Penicillin, ASA
• Stings
• Hymenoptera
• Exercise
• Latex

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Case

• 25m, healthy, comes from the gym
• flushing, pruritis, SOB, lightheadedness
• Pad Thai 4 hours prior

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Food Dependent Exercise Induced Anaphylaxis

• More prevalent that one would think
• 2-4 hours post ingestion
• Allergy testing helpful in avoidance

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Case

• 48m, healthy, severe flushing, pruritis,
  throbbing HA, diarrhea
• 15min post ahi tuna ingestion
• Vitals stable

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DDx

• Flushing syndromes
• Carcinoid
• VIP secreting tumours
• Restaurant syndromes
• MSG, sulfites
• Scombroidosis
• Endogenous Histamine syndromes
• Mastocytosis
• Leukemias
• Sepsis

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Case

• 62m, 30min post dinner
• Generalized flushing
• Vomited once, abdo cramping
• SOB/chest tightness
• HR 62 RR 28 BP 159/96 94 RA

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High Risk Groups

• Asthmatics
• Beta blocked
• CAD

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Biphasic Reaction

• lt 8 hours typical
• Can occur up to 72 hours
• 0.5 - 20 patients
• Less, equal or greater than initial reaction
• No clinical predictors
• Ingested allergen more often associated
• Corticosteroids do not clearly reduce incidence
  or severity

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Clinical Summary

• More than urticaria
• Fatal ABCs
• Timing of exposure
• Systems involved
• High risk PMHx
• Etiology
• Biphasic Hx

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Management

• ABCs
• Drugs
• Epinephrine
• SC/IM/IV
• nebulized
• Antihistamines
• Anti-H1 and H2
• Corticosteroids
• Bronchodilators
• Glucagon

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Epinephrine

• Alpha
• increases PVR
• decreases vascular permeability
• Beta
• bronchodilation
• stimulates increased cardiac output
• prevents further mediator release (cAMP)
• Side effects

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Epinephrine

• Drug of choice
• Mild-moderate systemic manifestations
• Epinephrine 11000
• Usual dose 0.3 mg 0.3mL
• Think epi-pen (small volume)
• IM dosing in thigh preferred (multiple studies
  demonstrating benefit over SC dosing in deltoid)
• Repeat every 5-10 minutes prn
• Severe life-threatening manifestations
• Epinephrine 110,000 (crash cart epi)
• Max single dose 0.1mg 1mL IV

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IV Epi

• Crash car epi
• Draw 1 mL into 10 mL syringe
• Fill up syring with NS
• 0.1mg total (10ug/mL)
• Give 1mL every 30-60 seconds
• Repeat

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Nebulized Epi

• 11000
• lt20kg, 2.5mL
• gt20kg, 5mL
• Can run continuous x 3
• Laryngeal edema
• Bronchoconstriction
• In some cases does actually reach therapeutic
  blood levels

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Management

• Diphenhydramine (anti H1)
• 50mg IV
• Ranitidine (anti H2)
• 50mg IV
• Methylprednisolone
• 125mg IV
• Glucagon
• 1-5mg IV q5min to effect
• Bronchodilators
• Continuous sabutamol/ipratropium nebs

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Case

• 20m asthmatic, wasp sting, generalized urticaria,
  hoarse voice, wheezing
• HR 130 RR 36 BP 110/70 sat 93 RA

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Airway in Anaphylaxis

• Early clues
• Nebulized epi
• Aggressive medical therapy
• Be humble/be prepared
• Backup help and DAC
• Dont paralyze
• Ketamine ideal
• Take a look

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Case

• 42f, flushed, pre-syncopal, N/V, SOB post cookie
  ingestion
• Looks unwell
• EMS have treated as per protocol
• HR 140 BP 88/56 RR 36 sats 95 RA

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Anaphylactic Shock

• Complex
• Vasodilation, leakage, intravascular depletion
• Fluids and Epi are key to Tx
• Bolus 2L immediately
• Can give epi peripherally
• You give the epi and run the scene
• Have someone else start CVC

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Disposition

• Controversial
• Nothing in literature to support set time
• Biphasic reaction usually lt 8 hours
• Severe reactions
• Admit for 24h if airway or BP was signficant
  concern

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Instructions

• Spend the time
• Allergen avoidance, symptom recognition, meds
• Script for Epi pen
• Need more than 1
• Steroids to go
• Benadryl to go
• Referral to allergist
• Via GP or directly

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Summary

• Multi-system
• High risk patients
• Biphasic reactions
• General management
• Focus on Epinephrine
• Airway management
• Shock management
• Disposition and instructions