AnaphylaxisAnaphylaxis

Mohan KamalanathanMohan KamalanathanEmergency DepartmentEmergency Department

Frankston HospitalFrankston Hospital

IntroductionIntroduction

• Definition.• Statistics.• Treatment.• Current trends.• Controversies.

Definition.Definition.

• ān'ə-fə-lāk'sĭs• Hypersensitivity especially in animals to a

substance, such as foreign protein or a drug, that is caused by exposure to a foreign substance after a preliminary exposure.

• Richet and Porter in 1902

Statistics.Statistics.

• ED presentations vary between 1 in 440 to 1 in 1500.

• Fatalities vary between 3 to 9% of presentations.

• True incidence in unknown as numbers are underestimated.

Variations in anaphylaxis.Variations in anaphylaxis.

• True anaphylaxis.• Anaphylactic shock.• Anaphylactoid reaction.

Clinical features.Clinical features.

• Cutaneous• Respiratory• Cardiovascular• Gastrointestinal• Other

Pathophysiology.Pathophysiology.

Airway oedema.Airway oedema.

Cutaneous features.Cutaneous features.

Treatment.Treatment.

• First line medication.– Position patient.

• Supine or left lateral.– Oxygen

• Keep sats > 92%.– Adrenaline

• 0.3 – 0.5 mls of 1:1000 IM.• Repeated 5 minutely.

– Fluids• Anything will do.

TreatmentTreatment

• Second line treatment:– Antihistamines

• H1 or H2 antagonists.

– Steroids• Oral vs. intravenous.

– Glucagon• 1 mg IV repeated every 5 minutes.

– Bronchodilators• Salbutamol or Adrenaline

Level of evidence in anaphylaxis.Level of evidence in anaphylaxis.

• Use of Oxygen:– Really good idea– No one has challenged it.

AdrenalineAdrenaline

– Cornerstone.– Lateral thigh IM injection better than other IM

routes as serum levels reliably achieved in 3 – 5 minutes.

• Level 3 evidence.– Continuous infusion safer than boluses.

• Level 3 evidence.

Fluids.Fluids.

– 20 ml/kg over 1 – 2 minutes.– No direct evaluation between colloid or

crystalloid.– Any fluid will do.

Antihistamines.Antihistamines.

– H2 antagonists (Ranitidine) help with the urticaria of anaphylaxis.

• Level 3 evidence.

– H1 antagonists (Promethazine) going out of fashion due to excessive sedation, vasodilatation and hypotension.

– Current trend is to use non-sedating H2 antihistamines.

Steroids.Steroids.

– Current practice is to use 250 mg Hydrocortisone intravenously.

– No comparative trials between methylprednisolone or dexamethasone.

– Thought to be useful for prevention of late phase occurrence.

Glucagon.Glucagon.

– Coming into vogue now.– Useful in pretreatment of a subgroup of

patients with anaphylaxis.– 1 mg intravenously.

Bronchodilators.Bronchodilators.

• Salbutamol.– Nebulised 5 mg with oxygen.– Useful as a temporising measure.

• Adrenaline.– Nebulised 5 mls 1:1000 undiluted.– Another temporising measure.

Controversies in anaphylaxis.Controversies in anaphylaxis.

• Dilution of adrenaline dose.• Observation period of 8 hours.

– Biphasic anaphylaxis is 1 – 5%.• Use of mast cell tryptase to confirm

diagnosis.

Key points.Key points.

• Adrenaline is main treatment.• All other treatments are unproven in

anaphylaxis, but are a good idea.• Drugs coming in vogue are:

– Non-sedating antihistamines.– Glucagon.

-I work very hard. Please don't expect me to think as well.-Love your enemies. At least they don't try to borrow money from

you.-There is no job so simple that it can not be done wrong.

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-I have seen the truth, and it makes no sense!-Never underestimate the power of human stupidity.

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nails.-If you're not part of the solution, be part of the problem!

-If you can not convince people, confuse them!

Rules to live by.Rules to live by.