Transcript Introduction

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*
Insect sting
3% of adults
Food
1-3% of children
Drug
1% of adults
RCM
0.1% of cases
Allergen immuno Tx
3% of patients
Latex
1% of adults
All causes
5% of adults
*urticaria / angioedema or dyspnea or hypotension
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
– H1+H2: 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 @ 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
Percentage
50
40
30
20
10
0
0-9
10-19 Age
20-29
Bock SA et al. J Allergy Clin Immunol 2001
30+
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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 (1:1000) IM q 10-20 min (max 0.3-0.5 ml)
– In shock, 0.5- 5 mcg/min (1:10,000) 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)


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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 patient’s 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
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 <100 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)

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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*
Percentage
95% CI
Crustaceans
Peanut
19
12
16 – 22
9 – 14
Fruits and vegetables
Fish
12
10
10 – 15
8 – 12
Tree nuts
9
7 – 11
Milk
Eggs
Additives
6
2
1
4–8
1–4
0.5 – 2
Other foods
36
33 – 40
* More than one option allowed.
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Presentation and ED Course
n=678
95% CI
Arrived by ambulance (%)
18
16 – 22
Duration of symptoms  1 hour (%)
37
33 – 41
Received antihistamines in ED (%)
72
68 – 75
Received systemic steroids in ED (%)
48
45 – 52
Received epinephrine in ED (%)
16
13 – 19
Respiratory treatments in ED* (%)
33
29 – 37
Discharged to home (%)
97
95 – 98
* Inhaled -agonists and inhaled anticholinergics
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Outcomes
Given discharge instructions to avoid
offending allergen (%)
Given prescription for self-injectable
epinephrine at ED or hospital
discharge (%)
Referred to an allergist at ED or
hospital discharge (%)
n=642
95% CI
40
36 – 43
16
14 - 20
12
9 - 15
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% given instructions to avoid offending allergen at discharge
Instructions to Avoid Offending Allergen
100
90
Overall: 40% (95% CI, 36-43%)
Goal = 100%
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Self-injectable Epinephrine at
Discharge
% prescribed self-injectable epinephrine at discharge
100
90
Goal = 100%
80
Overall: 16% (95% CI, 14-20%)
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Referred to Allergist at Discharge
100
% referred to an allergist at discharge
90
Goal = 100%
80
Overall: 12% (95% CI, 9-15%)
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Summary
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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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