Definitions Anaphylaxis : is a severe, life- threatening, generalised or systemic hypersensitivity reaction. Anaphylaxis is mediated by immunoglobulin E (IgE). Anaphylactoid reaction : is clinically indistinguishable from anaphylaxis, but are mediated by the drug or substance directly, and not by sensitised IgE antibodies. Foods Cows milk egg whites fish nuts (peanuts, Brazil nuts, almonds, hazelnuts, pistachios, pine nuts, cashews, sesame seeds, cottonseeds, sunflower seeds, millet seeds) shellfish Others : Bananas, beets, buckwheat, Chamomile tea, citrus fruits, kiwis, mustard, pinto beans, potatoes, rice, and seeds Venoms and saliva Hymenoptera (bees, wasps, yellow jackets, sawflies) Others : jellyfish, kissing bug (Triatoma), Deer flies, fire ants, rattlesnakes Drugs Antibiotics Penicillins Others : Amphotericin B, cephalosporins, chloramphenicol, ciprofloxacin, nitrofurantoin, streptomycin, tetracycline, vancomycin Aspirin and nonsteroidal anti-inflammatory drugs Miscellaneous other medications Opiates, succinylcholine, thiopental Allergy extracts, antilymphocyte and antithymocyte globulins, antitoxins, carboplatin, corticotropin, dextran, folic acid, insulin, iron dextran, mannitol, methotrexate, methylprednisolone, parathormone, progesterone, protamine sulfate, streptokinase,, trypsin, chymotrypsin, vaccines Latex rubber Radiographic contrast media Blood products Cryoprecipitate, immune globulin, plasma, whole blood Physical factors Cold temperatures, exercise Idiopathic Antigen enters body Mast cell degranulates, releases Histamine ;Leukotrienes ; Slow reacting substance of anaphylaxis (SRS-A) ; and Eosinophil chemotactic factor (ECF) Attaches to antibodies on mast or basophil cells Antigen reenters body Mast cells become sensitized Attach to surface of mast or basophil cells Antibodies produced Action of histamin Smooth muscle contraction Increased vascular permeability Inhibition of central, peripheral nervous system neurotransmitter release Gastric acid secretion Action of Leukotrienes Potent bronchoconstrictors vascular permeability & possibly coronary vasoconstriction The results are: Vasodilation Increased Capillary Permeability Smooth Muscle Spasm Cardiovascular Circulation problems can be caused by: direct myocardial depression vasodilation and capillary leak loss of fluid from the circulation Cardiovascular manifestations include: Hypotension and cardiovascular collapse Tachycardia Arrhythmias ECG may show ischaemic changes Cardiac arrest Bradycardia is usually a late feature, often preceding cardiac arrest Respiratory System Airway problems: Oedema of the glottis tongue and airway structures. The patient has difficulty in breathing and swallowing and feels that the throat is closing up Hoarse voice Stridor and airway obstruction Breathing problems: Dyspnea and tachypnea Bronchospasm (Wheeze) Confusion caused by hypoxia Cyanosis, this is usually a late sign Respiratory arrest Cutaneous They are often the first feature and present in over 80% of anaphylactic reactions Flushing Erythema Urticaria, they are usually itchy Angioedema,most commonly in the eyelids and lips, and sometimes in the mouth and throat Pruritus without rash Gastrointestinal abdominal pain diarrhoea or vomiting. Haematological Coagulopathy Neurological Dizziness syncope Seizure Diagnosis Anaphylaxis is likely when all of the following 3 criteria are met Sudden onset and rapid progression of symptoms Life-threatening Airway and/or Breathing and/or Circulation problems Skin and/or mucosal changes (flushing, urticaria, angioedema) The following supports the diagnosis Exposure to a known allergen for the patient Remember Skin or mucosal changes alone are not a sign of an anaphylactic reaction Skin and mucosal changes can be subtle or absent in up to 20% of reactions (some patients can have only a decrease in blood pressure. There can also be gastrointestinal symptoms (e.g. vomiting, abdominal pain, incontinence) Differential Diagnosis for Anaphylaxis Hypotension Septic shock Vasovagal reaction Cardiogenic shock Hypovolemic shock Respiratory distress with wheezing or stridor Airway foreign body Asthma and chronic obstructive pulmonary disease exacerbation Vocal chord dysfunction syndrome Postprandial collapse Airway foreign body Monosodium glutamate ingestion Sulfite ingestion Scombroid fish poisoning Flush syndrome Carcinoid Postmenopausal hot flushes Red man syndrome (vancomycin) Miscellaneous Panic attacks Systemic mastocytosis Hereditary angioedema Leukemia with excess histamine production Treatment of Anaphylaxis Immediate Treatment Removing the trigger for an anaphylactic reaction if possible and call for help Follow the ABCDE of resuscitation Adrenaline is the most useful drug for treating anaphylaxis as it is effective in bronchospasm and cardiovascular collapse If anaphylaxis is caused by an injection, administer aqueous epinephrine, 0.15 to 0.3 mL, into injection site to inhibit further absorption of the injected substance Place patient in recumbent position and elevate lower extremities Monitor vital signs Airway and Adrenaline Maintain airway and administer 100% oxygen Adrenaline: If i/v access available give 1:10,000 adrenaline in 0.5-1ml increments, repeated as required. Alternatively give i/m 0.5 1 mg (0.5 1 ml of 1: 1000 solution) repeated each 10 15 minutes as required for children: 0.01 mL per kg, up to a maximum dose of 0.2 to 0.5 mL by SC or IM route and, if necessary, repeat every 15 minutes Breathing Ensure adequate breathing Intubation and ventilation may be required Adrenaline will treat bronchospasm and swelling of the upper airway Nebulised bronchodilators (e.g. 5mg salbutamol) or i/v aminophylline (loading dose of 5mg/kg followed by 0.5mg/kg/hour). may be required if bronchospasm is refractory Circulation Adrenaline is the most effective treatment for severe hypotension Insert 1 or 2 large bore i/v cannulae and rapidly infuse normal saline Colloid may be used (unless it is thought to be the source of the reaction) Venous return may be aided by lifting the patients legs or tilting the patient head down If still hypotention consider use of a vasopressor such as dopamine Further Management Administer the antihistamine : H1 blocker diphenhydramine (adults: 25 to 50 mg; children: 1 to 2 mg per kg), usually given parenterally. and H2 blockers eg. ranitidine (50mg i/v slowly) or cimetidine (200mg i/v slowly) Corticosteroids : Give hydrocortisone 200mg i/v followed by mg 4 to 6 hourly Steroids will take several hours to work Adrenaline IV bolus dose adult Titrate IV adrenaline using 50 microgram boluses according to response If repeated adrenaline doses are needed, start an IV adrenaline infusion The pre-filled 10 mL syringe of 1:10,000 adrenaline contains 100 micrograms/mL A dose of 50 micrograms is 0.5 mL, which is the smallest dose that can be given accurately Do not give the undiluted 1:1000 adrenaline concentration IV Adrenaline IV bolus dose children IM adrenaline is the preferred route for children having an anaphylactic reaction The IV route is recommended only in specialist paediatric settings by those familiar with its use (e.g., paediatric anaesthetists, paediatric emergency physicians, paediatric intensivists) and if the patient is monitored and IV access is already available There is no evidence on which to base a dose recommendation the dose is titrated according to response A child may respond to a dose as small as 1 microgram/kg. This requires very careful dilution and checking to prevent dose errors.