ANAPHYLAXIS

• Definition of anaphylaxis:

  • Anaphylaxis is a medical emergency
  • Syndrome with varied mechanisms, clinical presentation, and severity
  • Requires prompt recognition of symptoms and immediate treatment
  • Results from a massive release of inflammatory mediators from mast cells and basophils
  • Occurs in all age groups but more commonly in adults
  • Common causes include food, drugs, insect venom, and latex
• Commonest foodstuffs that can cause anaphylaxis:

  • Hen's eggs
  • Peanuts
  • Milk
  • Tree nuts
  • Fish
  • Shellfish
  • Seeds
  • Rarer causes: fruits, vegetables, mammalian meat
• Diagnostic criteria for anaphylaxis:

  • Acute onset (minutes to hours) illness with involvement of skin/mucosa and airway compromise or hypotension/associated signs
  • Two or more of the following after exposure to the known allergen: skin/mucosa, respiratory compromise, hypotension/associated signs, or GI symptoms
  • Hypotension after exposure to a known allergen (minutes to hours) with low blood pressure for age or >30% decrease in systolic blood pressure
• First-line drug of choice for anaphylaxis:

  • No contraindications
  • Has alpha and beta adrenergic effects
  • Alpha effects: Increase vascular resistance and blood pressure, improves coronary artery perfusion, reduces angioedema and urticaria
  • Beta 1 effects: Positive inotropic and chronotropic effects
  • Beta 2 effects: Bronchodilation and inhibits release of inflammatory mediators
• Management of anaphylaxis:

  • Administer IV fluid for resuscitation
  • Give supplemental oxygen
  • Place the patient in a recumbent position with lower limbs elevated
  • Call for help
  • Give IMI adrenaline stat (0.01ml/kg) repeat every 5 minutes prn
  • Eliminate additional exposure to the allergen
• Further management of anaphylaxis:

  • Fluid replacement is crucial for circulatory failure and hypotension
  • Correction of hypovolemic shock with rapid fluid replacement and adrenaline is a major goal of treatment
  • Bronchodilators like nebulized Salbutamol every 20 minutes or by continuous infusion can be used
  • Antihistamines and corticosteroids are not useful for initial management but can be adjunctive after patient stabilization
• Checklist for management of anaphylaxis:

  • Stethoscope and blood pressure machine
  • Tourniquets, syringes, needles of different sizes
  • Injectable aqueous adrenaline 1:1000
  • Oral airway and endotracheal tubes
  • Equipment for administering oxygen
  • Diphenhydramine injectable
  • Corticosteroids for IV injection
  • Vasopressors
  • Glucagon
  • Automatic defibrillator
• Indications for EpiPen use:

  • Previous severe anaphylaxis to food, latex, aeroallergens
  • Coexistent unstable or moderate to severe asthma with food allergy
  • Exercise-induced anaphylaxis
  • Idiopathic anaphylaxis
  • Untreated venom allergy with systemic reactions
  • Underlying mast cell disorder with previous systemic reactions
• Disadvantages of EpiPen use:

  • Fixed doses available as 0.15mg and 0.30mg
  • Expensive
  • Limited shelf life
  • Limited availability
• Post-discharge care for anaphylaxis:

  • Have an EpiPen
  • Know how to use it
  • Have a Medic Alert disc/bracelet
  • Be aware of factors to avoid
  • Patient must be provided with an action plan with doctor's contact details
  • Family and colleagues must be made aware of the condition and action plan
  • Offer SCIT if bee venom anaphylactic