Anaphylaxis

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Anaphylaxis

• Clare Taylor
• Consultant in Emergency Medicne
• RUH Bath

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An ordinary day..
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A young man attends your surgery
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Complaining of a football stud injury
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He tells you he hasnt been fully immunised
against tetanus.
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You persuade him to have a booster.
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He thinks his lips are swelling up
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He comes out in large wheals
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He goes red
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Then he goes white
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He is sick as a parrot
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And feels a sense of impending doom..
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and collapses to the floor
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Whats going on?
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You inject 0.5mls1/1000 adrenalin i.m
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And call an ambulance
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By the time the ambulance arrives
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David tells the crew hes feeling much better
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He says that he doesnt want to go to hospital.

• But..

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Anaphylaxis is a game of two halves
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Biphasic anaphylaxis

• A recurrence of symptoms after a period of
  resolution without further exposure to the
  allergen
• Physiological mechanisms unclear
• Can be a life threatening event

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• Incidence 2 20
• Varying significance
• Risk factors suggested but not proven
• Wide range of remission times

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Summary of remission time evidence

• Of 32 biphasic reactions described in the
  literature (inc case reports) remission times
  range from 1 to 72 hours
• Median time 4.8 hours
• 6 hours obs 62.5, 8 hours 69, 3 more by 12
  hours, 20 over 24 hours.

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Resuscitation Council GuidelinesOBSERVE FOR AT
LEAST 6 HOURS

• Severe, idiopathic reactions of slow onset
• Reactions with severe asthmatic component, or in
  severe asthmatics
• Possible continuing allergen exposure (eg
  ingestion)
• Previous history of biphasic reaction

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Should David have an Epipen?
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RUH ED Observation Unit Pathway

• Medically stable
• Hydrocortisone and Chlorpheniramine
• H2 Antagonist
• 8 hours observation
• Mast Cell triptase
• Referral to immunologist
• Epipen prescription and training

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Game Over!
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Any questions?