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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 www.emnet-usa.org Outline Case Presentation Prevalence and Natural History Pathophysiology ED Diagnosis and Management Food-related Allergic Reactions Post-care Plans www.emnet-usa.org 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 www.emnet-usa.org 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 www.emnet-usa.org Anaphylaxis Multi-system syndrome resulting from mediator release Acute onset Varies from mild and self-limited to fatal IgE and non-IgE mediated www.emnet-usa.org 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 www.emnet-usa.org 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 www.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 www.emnet-usa.org 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 www.emnet-usa.org 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 www.emnet-usa.org Causes of Anaphylaxis www.emnet-usa.org 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 www.emnet-usa.org Causes of Anaphylactoid Mediator Release Complement activation – Iodinated dye – Aggregated IgG – IgA deficiency Unknown mechanisms – Aspirin – Opiates – Local anesthetics www.emnet-usa.org Severity of Anaphylaxis Risk Factors Male Consistent antigen administration Shorter time elapsed since last reaction Asthma www.emnet-usa.org Anaphylaxis Fatalities Post Mortem Findings Airway (laryngeal) and tissue (visceral) edema Pulmonary hyperinflation Tissue eosinophilia Elevated serum tryptase Myocardial injury www.emnet-usa.org 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 www.emnet-usa.org 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+ www.emnet-usa.org Anaphylaxis Differential Diagnosis Vasovagal syncope Systemic mastocytosis Scombroid (fish) poisoning Other causes of shock www.emnet-usa.org Anaphylaxis Diagnosis Clinical features Serum tryptase (measurable up to 6 hours) www.emnet-usa.org 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) www.emnet-usa.org 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) www.emnet-usa.org 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 www.emnet-usa.org 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 www.emnet-usa.org Food-Related Allergic Reaction Epidemiology Fatal Peanut Schools Exercise www.emnet-usa.org 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 www.emnet-usa.org 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% www.emnet-usa.org 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 www.emnet-usa.org 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 www.emnet-usa.org 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) www.emnet-usa.org “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 www.emnet-usa.org EMNet Sites (137 US sites) 9/22/04 www.emnet-usa.org 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) www.emnet-usa.org 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 www.emnet-usa.org 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. www.emnet-usa.org 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 www.emnet-usa.org 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 www.emnet-usa.org % given instructions to avoid offending allergen at discharge Instructions to Avoid Offending Allergen 100 90 Overall: 40% (95% CI, 36-43%) Goal = 100% 80 70 60 50 40 30 20 10 0 M O R Q I S J L P H C E A N B K F T G D Site www.emnet-usa.org Self-injectable Epinephrine at Discharge % prescribed self-injectable epinephrine at discharge 100 90 Goal = 100% 80 Overall: 16% (95% CI, 14-20%) 70 60 50 40 30 20 10 0 B F N Q D I E K P G L R C T S H U J M O Site www.emnet-usa.org Referred to Allergist at Discharge 100 % referred to an allergist at discharge 90 Goal = 100% 80 Overall: 12% (95% CI, 9-15%) 70 60 50 40 30 20 10 0 H K Q R E P B D I L S C G M N J A T F O Site www.emnet-usa.org 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 www.emnet-usa.org 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 www.emnet-usa.org 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 www.emnet-usa.org 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 www.emnet-usa.org