Investigation of Anaesthetic Drug Allergies

Question 1

What is anaphylaxis?

Answer 1

Massive degranulation of mast cells causing release of inflammatory cytokines and chemical mediators into circulation

Question 2

Where are mast cells found?

Answer 2

In skin, mucosa and other areas

Question 3

What does the degranulation of mast cells result in?

Answer 3

Rapid release inflammatory mediators Followed by delayed secretion inflammatory cytokines

Question 4

Different grades of severity of anaphylaxis

Answer 4

Question 5

What is ‘perioperative anaphylaxis’?

Answer 5

The incidence of anaphylaxis during general anesthesia

Question 6

What is the treatment for anaphylaxis?

Answer 6

ADRENALINE & FLUIDS:

• Adrenaline –> IM injection in lateral thigh
  
  • Stimulates alpha and beta adrenergic receptors in lungs and heart:
    
    • Increased vasoconstriction, ionotropic effects on heart, increased peripheral vascular resistance, raised blood pressure
    • Bronchodilation
    • Inhibition of mediatory release –> stops onward mast cell degranulation (beta receptors on mast cells)
• Fluids
  
  • ​Treats hypovolaemia caused by increased vascular permeability caused by histamine that has led to leakage of fluid

Question 7

If adrenaline and fluids don’t work during treatment of anaphylaxis, what do you do?

Answer 7

Give more adrenaline and fluids –> if this still doesn’t work, consider vasopressin and glucagon

Question 8

What are other therapeutic options during anaphylaxis?

Answer 8

• Steroids
• Antihistamines

These are not first line treatments as neither will prevent the ongoing degranulation of mast cells nor will they provide rapid relief of symptoms

Question 9

How can antihistamines and steroids provide relief from anaphylaxis?

Answer 9

reduce inflammation of your air passages and improve breathing

Question 10

If a patient suffers perioperative anaphylaxis, what is then required after treatment?

Answer 10

High quality referral to allergy clinic is vital

Question 11

Why are tryptase samples needed by the allergy clinic after perioperative anaphylaxis?

Answer 11

Histamine has a very short half-life (minutes) so hard to capture with a blood test. Tryptase is used instead. Serum Tryptase is a marker of mast cell degranulation.

Question 12

What is chlorhexidine?

Answer 12

a disinfectant and antiseptic that is used for skin disinfection before surgery and to sterilise surgical instruments.

Question 13

What is chlorhexidine anaphylaxis?

Answer 13

• Chlorhexidine causes 10-15% of all peri-op anaphylaxis
• Severe, IgE-mediated reactions
• ‘Hidden allergen’

Question 14

What parts of patient history may indicate a chlorhexidine allergy?

Answer 14

• Urticaria at cannula site / with Hibiscub
• Problems with cosmetic products

Question 15

What are the main 4 causal agents for perioperative anaphylaxis?

Answer 15

1. Antibiotics
2. Neuromuscular blocking agents
3. Chlorhexidine
4. Patent blue dye (used in breast cancer surgery)

Question 16

What is Teicoplanin?

Answer 16

An antibiotic used in the prophylaxis and treatment of serious infections caused by Gram-positive bacteria, including MRSA and Enterococcus faecalis.

Question 17

How is Teicoplanin clinically important in anaphylaxis?

Answer 17

• Most allergenic drug –> 17x more likely to cause anaphylaxis than co-amoxiclav
• 50% of cases occur when patient is ‘penicillin-allergic’

Question 18

What % of penicillin allergy labels are wrong?

Answer 18

95-98%

Question 19

How is penicillin allergy tested for?

Answer 19

• History from patient
• Skin test
• Challenge test (definitive test)
  
  • Give patient drug in supervised setting

Question 20

When taking history for drug allergy, what should be asked?

Answer 20

Finding out if it is IgE mediated type I reaction:

• Shortness of breath
• Cough
• Wheeze
• Swelling
• Urticarial rash
• Reactions occur after 1st dose (not 2/3 days in)
• Required treatment involves adrenaline

Question 21

What is the most used laboratory test to confirm anaphylaxis?

Answer 21

serum tryptase concentration - tryptase is the best biomarker to assess mast cell activation as levels are increased from 15 min to 3 h after anaphylaxis onset

Question 22

Why are tryptase levels used instead of histamine levels to confirm anaphylaxis?

Answer 22

Histamine has a very short half life (minutes)

Question 23

What is tryptase?

Answer 23

Tryptase is an enzyme that is released, along with histamine and other chemicals, from mast cells when they are activated as part of a normal immune response as well as in allergic (hypersensitivity) responses.

Question 24

Which chemical used as a skin and surgical instrument disinfectant can also be found in cosmetic products?

Answer 24

Chlorhexidine