Allergic Reactions & Anaphylaxis EMS Professions Temple College Incidence In USA - 400 to 800 deaths/year Parenterally administered penicillin accounts for 100 to 500 deaths per year Hymenoptera stings account for 40 to 100 deaths per year Risk factors: beta-blockers, adrenal insufficiency Causes of Deaths Laryngeal edema and acute bronchospasm with respiratory failure account for >70% Circulatory collapse accounts for 25% Other <5% - ?brain ?MI Allergic Reaction Physiologic response to antigens – Oversensitive response = allergic – Occurs after sensitization to antigen Antigen binds with Antibody – Less severe result in inflammatory response – Type I reaction involves antibodies attached to mast cells or basophils = most severe form Anaphylaxis Systemic reaction of multiple organ systems to antigen-induced IgE-mediated immunulogic mediator release in previously sensitized individual Allergic Reaction Antigen – Induces antibody formation – Examples » Drugs (antibiotics) » Foods (nuts, shellfish) » Insect venoms » Animal serum » Incompatible blood types Anaphylaxis Antigens enter body by: – Injection – Ingestion – Inhalation – Absorption Anaphylaxis Pathophysiology Antigen enters body Antibodies produced Attach to surface of mast or basophil cells Mast cells become sensitized Anaphylaxis Pathophysiology Mast cells – In all subcutaneous/submucosal tissues, – Including conjunctiva, upper/lower respiratory tracts, and gut Basophils – Circulate in blood Anaphylaxis Pathophysiology Antigen reenters body Attaches to antibodies on mast or basophil cells Mast cell degranulates, releases – Histamine – Leukotrienes – Slow reacting substance of anaphylaxis (SRS-A) – Eosinophil chemotactic factor (ECF) Histamine Three histamine receptor types: – H1 – H2 – H3 Histamine Acts on H1 receptors to cause – Smooth muscle contraction – Increased vascular permeability – Prostaglandin generation Histamine Acts on H2 receptors to cause – Increased vascular permeability – Gastric acid secretion – Stimulation of suppressor lymphocytes – Decreased PMN enzyme release – Release of more histamine from mast cells and basophils Histamine Acts on H3 receptors to cause – Inhibition of central, peripheral nervous system neurotransmitter release – Inhibition of further histamine formation, release Vasodilation Decreased peripheral vascular resistance Hypotension Tachycardia Peripheral hypoperfusion Increased Capillary Permeability Tissue edema, urticaria (hives), itching Laryngeal edema – Airway obstruction – Respiratory distress – Stridor Fluid leakage from vascular space – Hypovolemic shock Urticaria Smooth Muscle Spasm Bronchospasm Bladder Spasm – Respiratory distress – Urinary urgency – “Tight Chest” – Urinary incontinence – Wheezing GI Tract Spasm – Nausea, vomiting – Cramping, diarrhea Anaphylactic Reaction Leukotrienes – Potent bronchoconstrictors, vascular permeability & possibly coronary vasoconstriction – Slower onset than histamine – Effects last longer than histamine Allergic Reactions Generally classified into 3 groups: – Mild allergic reaction – Moderate allergic reaction – Severe allergic reaction (anaphylaxis) Mild Allergic Reaction Characteristics – Urticaria (hives), itchy – Erythema (redness) – Rhinitis – Conjunctivitis – Mild bronchoconstriction – Usually localized (look on abdomen, chest, back) No SOB or hypotension/hypoperfusion Often self-treated at home Moderate Allergic Reaction Characteristics – Mild signs/symptoms with any of following: » Dyspnea, possibly with wheezes » Angioneurotic edema » Systemic, not localized No hypotension/hypoperfusion Severe Allergic Reaction (Anaphylaxis) Characteristics – Mild and/or moderate signs/symptoms plus – Shock / hypoperfusion Clinical Manifestation Dependent on: – Degree of hypersensitivity – Quantity, route, rate of antigen exposure – Pattern of mediator release – Target organ sensitivity and responsiveness Clinical Manifestation Severity varies from mild to fatal Most reactions are respiratory, dermatologic Less severe early findings may progress to life- threatening over a short time Initial signs/symptoms do NOT necessarily correlate with severity, progression, duration of response Generally, quicker symptoms = more severe reactions Clinical Manifestation First manifestations involve skin – Warmth and tingling of the face, mouth, upper chest, palms and/or soles, or site of exposure – Erythema – Pruritus is universal feature, erythema – May be accompanied by generalized flushing, urticaria, nonpruritic angioedema Clinical Manifestation May progress to involvement of respiratory system – cough – chest tightness – dyspnea – wheezing – throat tightness – dysphagia – hoarseness Clinical Manifestation Other Signs and Symptoms – lightheadedness or syncope caused by hypotension or dysrhythmia – nasal congestion and sneezing – ocular itching and tearing – cramping abdominal pain with nausea,vomiting, or diarrhea – bowel or bladder incontinence – decreased level of consciousness Clinical Manifestation Physical Exam findings may include – urticaria, angioedema, rhinitis, conjunctivitis – tachypnea, tachycardia, hypotension – laryngeal stridor, hypersalivation, hoarseness, angioedema Insect Sting Hypersensitivity Hymenoptera - yellow jackets, honeybees, hornets, wasps, bumble bees 90%: Local hives, pruritus 10%: Massive local reaction, including swelling beyond two joints of extremity 1%: Systemic reaction 10%: have worse reaction on second sting 28%: have recurrent systemic reaction Management Treatment depends upon severity of reaction and signs/symptoms of its presentation Management Optimal management requires – High index of suspicion (suspect, treat within minutes) – Early diagnosis – Pharmaceutical intervention – Observation – Disposition Patient Self-Management Benadryl 50 mg p.o. At any sign of anaphylaxis, self-administer subcutaneous epinephrine (Epi-Pen®, Ana- Kit®) If short of breath or wheezing, use aerosolized epinephrine (Primatene Mist, Medihaler-Epi) Mild Allergic Reaction Often self-treated at home Diphenhydramine 25 - 50mg PO or IM – IV is acceptable but should include transport If stinger present, flick it away with credit card or fingernail May consider (if available and indicated): – cimetidine or ranitidine – prednisone – inhaled beta-agonists Moderate Allergic Reaction High flow oxygen IV NS – Titrated to systolic BP 90 mm Hg ECG monitor Beta agonists – Nebulized albuterol, isoetharine, terbutaline – SQ terbutaline or epinephrine 1:1000 or IV aminophylline if severe bronchoconstriction Diphenhydramine 25-50 mg IM or IV Methylprednisolone 125 mg IV Transport Anaphylaxis Airway and Breathing – High concentration oxygen – Ventilations, ETT, alternative airway prn – Consider inhaled beta agonists Circulation – Large bore IV NS X 2 – Quickly titrate fluids to perfusion with bolus therapy – ECG monitor Treat as pre-arrest patient Anaphylaxis Epinephrine 0.5 - 1.0 mg 1:10,000 IV prn – Hypotension unresponsive to fluids and epinephrine consider dopamine ~10 mcg/kg/min – Bronconstriction unresponsive to Epi consider aminophylline Diphenhydramine 50 mg IV Methylprednisolone 125 mg IV Consider MAST if unresponsive to fluids Rapid transport Disposition Regardless of response to therapy, all patients with systemic features must be observed for 6 to 8 hours Latex Allergies Due to a growing number of persons experiencing latex allergies, EMS providers should be prepared to treat patients with such allergies – Have latex free equipment – Use the patient’s latex free supplies Case Presentation #1 You are dispatched to an electronics manufacturing plant to see a 28-year-old woman. The woman believes she is having an allergic reaction. Security officers will meet you at the front gate and escort you to the patient. What specific information would you like at this point? Case Presentation #1 You find this patient in an office area sitting at her desk. From a distance, you notice she is awake and speaking clearly. She does not appear to have any breathing difficulty. She states she had just returned from lunch and began to feel hot and light headed. Her friend pointed out that the patient’s arms and neck are very red, and that her face appears “puffy”. Case Presentation #1 The patient states she is allergic to peanuts but has not eaten any. She went to a health food café where she had grilled chicken and steamed vegetables. She has no other past history and takes no medications. Her last allergic rx was similar to this. Vitals are: BP-116/70; Pulse-100; RR-20; Lung sounds-clear and equal. No difficulty swallowing, redness to her arms, chest, neck and face. Would you like to perform any other procedures/exams/testing or obtain other history before treating? Case Presentation #1 So, what is your complete treatment plan for this patient? Case Presentation #2 39 year-old male found at home in respiratory arrest with a bradycardic carotid pulse. His wife states he was helping a friend paint when he was apparently stung by a bee. He walked into the house, saying “I don’t feel good,” and collapsed. Case Presentation #2 PMH: depression, gastritis, seasonal allergies Medications: Ritalin, Zantac, Prozac, Claritin No known drug allergies No prior reactions to hymenoptera What therapies would you like to begin for this man? Case Presentation #2 You have done the following: – intubated orotracheally – administered intravenous epinephrine, 0.5 mg & diphenhydramine 50 mg – started 2 large-bore IVs of NS and given 500 cc fluid At this point, the patient no longer has a pulse Case Presentation #2 You begin CPR and give the following: – Dopamine drip at 10 mcg/kg/min – Epinephrine, 1:10,000, 1 mg IV q 3-5 min You now note the following: – ECG: Idioventricular rhythm – Lung Sounds: difficult to hear – Obvious facial edema Can you think of any ideas for further treatment?
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