Anaphylaxis

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Anaphylaxis Acute Allergic Reactions in the
Emergency Department

• Theodore J. Gaeta, DO, MPH
• Sunday Clark, MPH
• Carlos A. Camargo, Jr., MD, DrPH
• On behalf of the MARC Investigators

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Outline

• Case Presentation
• Prevalence and Natural History
• Pathophysiology
• ED Diagnosis and Management
• Food-related Allergic Reactions
• Post-care Plans

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Case Presentation

• 19 year old female with acute onset dyspnea
• Dyspnea, wheezing, vomiting and generalized
  flushing
• minutes after eating a chocolate chip cookie
• Past medical history eczema

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Case Presentation (continued)

• Vital signs
• SBP 80/p, P 124, R 40, T 98.8oF (37.1oC)
• Airway patent, diminished breath sound at the
  bases with wheezing in the upper fields
• Weak pulses with delayed capillary refill
• Diffuse erythematous rash observed and Medic
  Alert tag indicates peanut allergy

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Anaphylaxis

• Multi-system syndrome resulting from mediator
  release
• Acute onset
• Varies from mild and self-limited to fatal
• IgE and non-IgE mediated

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Anaphylaxis

• Incidence
• 21 per 100,000 person-years (95 confidence
  interval CI 17 - 25 per 100,000 person-years)1
• 10.5 per 100,000 person-years among children (95
  CI 8.1 13.3 per 100,000 person-years)2

1Yocum et al. J Allergy Clin Immunol 1999 2Bohlke
et al. J Allergy Clin Immunol 2004
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Estimated prevalence of Generalized Allergic
Reaction
urticaria / angioedema or dyspnea or hypotension
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Anaphylaxis - Clinical Manifestations

• Cardiovascular
• Tachycardia then hypotension
• Shock 50 intravascular volume loss
• Bradycardia (4) (transient or persistent)
• Myocardial ischemia
• Lower respiratory bronchoconstriction wheeze,
  cough, shortness of breath
• Upper respiratory
• Laryngeal/pharyngeal edema
• Rhinitis symptoms

Fisher. Anesth Intens Care 1986
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Anaphylaxis - Clinical Manifestations

• Cutaneous
• Pruritus, urticaria, angioedema, flushing
• Gastrointestinal
• Nausea, emesis, cramps, diarrhea
• Ocular
• Pruritus, tearing, redness
• Genitourinary
• Urinary urgency, uterine cramps

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Anaphylaxis -Temporal Pattern

• Uniphasic
• Biphasic
• Initial allergic reaction
• Recurrence of same manifestations up to 8 hours
  later
• Protracted
• Up to 32 hours
• May not be prevented by glucocorticoids

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Anaphylaxis Mediators

• Histamine
• H1 smooth muscle contraction vasc
  permeability
• H2 vascular permeability
• H1H2 vasodilatation, pruritus
• Leukotrienes
• Smooth muscle contraction
• vascular permeability and dilatation
• Nitric Oxide
• Smooth muscle relaxation
• vascular permeability and dilatation

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Causes of Anaphylaxis
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Causes of IgE-Mediated Anaphylaxis

• Antibiotics and other medications
• ?-lactams, tetracyclines, sulfas
• Foreign proteins
• Latex, hymenoptera venoms, heterologous sera,
  protamine, seminal plasma, chymopapain
• Foods
• Shellfish, peanuts, and tree nuts
• Exercise induced

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Causes of Anaphylactoid Mediator Release

• Complement activation
• Iodinated dye
• Aggregated IgG
• IgA deficiency
• Unknown mechanisms
• Aspirin
• Opiates
• Local anesthetics

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Severity of Anaphylaxis

• Risk Factors
• Male
• Consistent antigen administration
• Shorter time elapsed since last reaction
• Asthma

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Anaphylaxis Fatalities

• Post Mortem Findings
• Airway (laryngeal) and tissue (visceral) edema
• Pulmonary hyperinflation
• Tissue eosinophilia
• Elevated serum tryptase
• Myocardial injury

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Anaphylaxis Fatalities

• Fatalities _at_ 4
• Increased risk
• ? blockade, severe hypotension, bradycardia,
  sustained bronchospasm, poor response to
  epinephrine
• Adrenal insufficiency
• Asthma
• Coronary artery disease

Van der Klauw et al. Clin Exp Allergy 1996
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Anaphylaxis Fatalities
60
50
40
Percentage
30
20
10
0
0-9
10-19
20-29
30
Age
Bock SA et al. J Allergy Clin Immunol 2001
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Anaphylaxis Differential Diagnosis

• Vasovagal syncope
• Systemic mastocytosis
• Scombroid (fish) poisoning
• Other causes of shock

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Anaphylaxis Diagnosis

• Clinical features
• Serum tryptase
• (measurable up to 6 hours)

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Anaphylaxis Treatment

• O2 , airway maintenance IV fluids
• Loose tourniquet? (to extremity for bee sting)
• Epinephrine
• 0.01 ml/kg (11000) IM q 10-20 min (max 0.3-0.5
  ml)
• In shock, 0.5- 5 mcg/min (110,000) IV to
  maintain SBP
• H1 H2 histamine receptor antagonists
• Diphenhydramine, 1 mg/kg PO/ IM/ IV (max 75 mg)
• Ranitidine
• Adult, 4 mg/kg PO (max 300 mg), 50 mg IM/IV q 6 h
  
• Child, 1.5 mg/kg IM/IV (max 50 mg)

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Treatment (continued)

• Corticosteroids
• 1-2 mg/kg prednisone PO (max 75 mg)
• 2 mg/kg methylpredisolone IV (max 250 mg)
• Not effective in protracted anaphylaxis
• Effective in iodinated dye prophylaxis
• Inhaled beta-agonists
• Albuterol 2.5 mg q 15-20 min
• Glucagon (consider if patient is on ?-blocker)

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Return to case

• Placed on supplemental O2 and cardiac monitor
• IV access and fluid bolus
• Albuterol via nebulizer
• Epinephrine 0.3 ml IM
• Diphenhydramine 50 mg IV
• Ranitidine 50 mg IV
• Methylpredisolone 125 mg IV

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Response

• Despite multiple doses of epinephrine and
  albuterol the patient remained in respiratory
  distress
• Impending respiratory failure
• Rapid sequence intubation
• Transferred to ICU
• Further history
• The patients roommate presents a Medic Alert
  tag indicating peanut allergy

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Food-Related Allergic Reaction

• Epidemiology
• Fatal
• Peanut
• Schools
• Exercise

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Fatal Food Anaphylaxis

• Frequency (USA) 150 deaths / year
• Risk
• Underlying asthma
• Delayed epinephrine
• Symptom denial
• Previous severe reaction
• History known allergic food
• Key foods peanut / tree nuts / shellfish
• Biphasic reaction
• Lack of cutaneous symptoms

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Prevalence of Food Allergy

• Perception by public 20-25
• Confirmed allergy (oral challenge)
• Adults 1-2
• Infants/Children 6-8
• Dye / preservative allergy (rare)
• Specific Allergens
• Dependent upon societal eating pattern
• Milk (infants) 2.5
• Peanut / tree nuts in general population 1.1

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Diagnosis History / Physical

• History symptoms, timing, reproducibility
• Acute reactions vs. chronic disease
• Diet details / symptom diary
• Specific causal food(s)
• Hidden ingredient(s)
• Physical examination evaluate disease severity
• Identify general mechanism
• Allergy vs. intolerance
• IgE vs. non-IgE mediated

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Disposition

• Most patients with allergic reactions can be
  discharged
• Hospitalize or observe patients with airway
  angioedema, persistent brochospasm,
  hypoperfusion, cardiac problems, on ?-blockers
• Observe 4 to 6 hours

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Risk Management for Anaphylaxis

• Education
• Allergen avoidance
• Written emergency action plan
• Resources (eg, FAAN website www.foodallergy.org)
• Prescription for self-injectable epinephrine
• Referral to an allergy specialist

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Anaphylaxis Operational Definition

• Two or more organ systems
• skin (e.g., hives)
• respiratory (e.g., swelling of the lips, tongue,
  or throat trouble breathing or shortness of
  breath stridor, wheezing)
• cardiovascular (e.g., hypotension, dizziness or
  fainting, altered mental status)
• gastrointestinal (e.g., trouble swallowing,
  abdominal pain)
• Hypotension (SBP lt100 mmHg)

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State of the ED
Objective To describe ED management of food
allergy
Methods The Multicetner Airway Research
Collaboration is a program within the Emergency
Medicine Network (www.emnet-usa.org)
Clark et al. J Allergy Clin Immunol 2004
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EMNet Sites (137 US sites)
9/22/04
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Methods (continued)

• 21 North American EDs participated in this study
• Chart review of randomly selected patients
  presenting to the ED over a one year period with
  physician-diagnosed food allergy
• ICD-9 codes
• 693.1 (dermatitis due to food)
• 995.0 (other anaphylactic shock)
• 995.3 (allergy, unspecified)
• 995.60 (allergy due to unspecified food)
• 995.61-995.69 (allergy due to specified foods)

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Results

• 678 patients with physician-identified food
  allergy were randomly selected for chart review
• 57 female, 43 white
• Mean age, 29 18 years
• 92 had documentation of a specific food item as
  the cause of the current reaction
• Only 41 of patients had documentation of a
  history of allergic reaction to the specific food
  that caused the current reaction

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Specific Foods
More than one option allowed.
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Presentation and ED Course
Inhaled ?-agonists and inhaled anticholinergics
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Outcomes
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Instructions to Avoid Offending Allergen
Overall 40 (95 CI, 36-43)
Goal 100
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Self-injectable Epinephrine at Discharge
Goal 100
Overall 16 (95 CI, 14-20)
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Referred to Allergist at Discharge
Goal 100
Overall 12 (95 CI, 9-15)
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Summary

• Although allergic reactions to food can be life
  threatening, 18 of patients came to the ED by
  ambulance and only 3 were admitted
• A variety of foods provoked the allergic
  reaction, with crustaceans and peanuts being the
  most common triggers
• Only 16 of patients received a prescription for
  self-injectable epinephrine when leaving the ED

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Summary (continued)

• Similarly, only 12 were referred to an allergist
  as part of discharge instructions
• At a minimum, there is poor documentation of
  medications prescribed at ED discharge
• Although guidelines suggest specific approaches
  for the emergency management of food allergy,
  concordance to these guidelines appears low

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Take Home

• Keys to successful management
• Prompt recognition of the signs and symptoms of
  anaphylaxis
• Early administration of IM epinephrine
• Volume resuscitation
• Comfort and familiarity with 2nd line therapies

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Take Home (continued)

• A successful post-care plan must include
• Education
• Allergen avoidance
• Written emergency action plan
• Educational resources
  (eg, www.foodallergy.org)
• Prescription for self-injectable epinephrine
• Referral to an allergy specialist

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