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

11Yocum et al. J Allergy Clin Immunol 1999Yocum et al. J Allergy Clin Immunol 199922Bohlke et al. J Allergy Clin Immunol 2004Bohlke et al. J Allergy Clin Immunol 2004

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Estimated prevalence of Generalized Allergic Reaction*

Insect sting

Food

Drug

RCM

Allergen immuno Tx

Latex

All causes

of adults

of children

of adults

of cases

of patients

of adults

of adults

3%

1-3%

1%

0.1%

3%

1%

5%

*urticaria / angioedema or dyspnea or hypotension*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 1986Fisher. Anesth Intens Care 1986www.emnet-usa.org

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 1996Van der Klauw et al. Clin Exp Allergy 1996www.emnet-usa.org

Anaphylaxis Fatalities

Bock SA et al. J Allergy Clin Immunol 2001Bock SA et al. J Allergy Clin Immunol 2001

0-9 10-19 20-29 30+0

10

20

30

40

50

60

Pe

rce

nta

ge

Age

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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)

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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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

Fatal Food Anaphylaxis

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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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ObjectiveTo describe ED management of food allergy

MethodsThe Multicetner Airway Research Collaboration is a program within the Emergency Medicine Network (www.emnet-usa.org)

“State of the ED”

www.emnet-usa.orgClark et al. J Allergy Clin Immunol 2004Clark et al. J Allergy Clin Immunol 2004

EMNet Sites (137 US sites)

www.emnet-usa.org9/22/04

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. www.emnet-usa.org

Percentage 95% CI

Crustaceans 19 16 – 22

Peanut 12 9 – 14

Fruits and vegetables 12 10 – 15

Fish 10 8 – 12

Tree nuts 9 7 – 11

Milk 6 4 – 8

Eggs 2 1 – 4

Additives 1 0.5 – 2

Other foods 36 33 – 40

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 anticholinergicswww.emnet-usa.org

Outcomes

n=642 95% CI

Given discharge instructions to avoid offending allergen (%)

40

36 – 43

Given prescription for self-injectable epinephrine at ED or hospital discharge (%)

16

14 - 20

Referred to an allergist at ED or hospital discharge (%)

12

9 - 15

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M O R Q I S J L P H C E A N B K F T G D0

10

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80

90

100

% g

ive

n in

stru

ctio

ns

to a

void

off

en

din

g a

llerg

en

at

dis

cha

rge

Site

Instructions to Avoid Offending Allergen

Goal = 100% Overall: 40% (95% CI, 36-43%)

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B F N Q D I E K P G L R C T S H U J M O0

10

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50

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90

100

% p

resc

ribe

d se

lf-in

ject

able

epi

nep

hrin

e a

t dis

cha

rge

Site

Self-injectable Epinephrine at Discharge

Goal = 100% Overall: 16% (95% CI, 14-20%)

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H K Q R E P B D I L S C G M N J A T F O0

10

20

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50

60

70

80

90

100

% r

efer

red

to a

n al

lerg

ist a

t dis

char

ge

Site

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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