Investigation of Anaesthetic Drug Allergies Flashcards Preview

Yr 2 - EMS > Investigation of Anaesthetic Drug Allergies > Flashcards

Flashcards in Investigation of Anaesthetic Drug Allergies Deck (24)
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1
Q

What is anaphylaxis?

A

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

2
Q

Where are mast cells found?

A

In skin, mucosa and other areas

3
Q

What does the degranulation of mast cells result in?

A

Rapid release inflammatory mediators Followed by delayed secretion inflammatory cytokines

4
Q

Different grades of severity of anaphylaxis

A
5
Q

What is ‘perioperative anaphylaxis’?

A

The incidence of anaphylaxis during general anesthesia

6
Q

What is the treatment for anaphylaxis?

A

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
7
Q

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

A

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

8
Q

What are other therapeutic options during anaphylaxis?

A
  • 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

9
Q

How can antihistamines and steroids provide relief from anaphylaxis?

A

reduce inflammation of your air passages and improve breathing

10
Q

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

A

High quality referral to allergy clinic is vital

11
Q

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

A

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.

12
Q

What is chlorhexidine?

A

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

13
Q

What is chlorhexidine anaphylaxis?

A
  • Chlorhexidine causes 10-15% of all peri-op anaphylaxis
  • Severe, IgE-mediated reactions
  • ‘Hidden allergen’
14
Q

What parts of patient history may indicate a chlorhexidine allergy?

A
  • Urticaria at cannula site / with Hibiscub
  • Problems with cosmetic products
15
Q

What are the main 4 causal agents for perioperative anaphylaxis?

A
  1. Antibiotics
  2. Neuromuscular blocking agents
  3. Chlorhexidine
  4. Patent blue dye (used in breast cancer surgery)
16
Q

What is Teicoplanin?

A

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

17
Q

How is Teicoplanin clinically important in anaphylaxis?

A
  • Most allergenic drug –> 17x more likely to cause anaphylaxis than co-amoxiclav
  • 50% of cases occur when patient is ‘penicillin-allergic’
18
Q

What % of penicillin allergy labels are wrong?

A

95-98%

19
Q

How is penicillin allergy tested for?

A
  • History from patient
  • Skin test
  • Challenge test (definitive test)
    • Give patient drug in supervised setting
20
Q

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

A

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
21
Q

What is the most used laboratory test to confirm anaphylaxis?

A

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

22
Q

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

A

Histamine has a very short half life (minutes)

23
Q

What is tryptase?

A

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.

24
Q

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

A

Chlorhexidine

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