Allergy including latex

Question 1

What is the incidence of anaphylaxis in anaesthesia

Answer 1

1 in 10 000 - 1 in 20 000

Question 2

What % of anaphylactic reations are fatal

Answer 2

10%

Question 3

Rank the agents (including latex) used in anaesthetics according to how frequently they cause anaphylaxis reactions during anaesthesia

Answer 3

1
Muscle relaxant - 58.2%

2
Latex - 16.7%

3
Antibiotics - 15.1%

4
Colloids - 4%

5
Hypnotics - 3.4 %

6
Opioids - 1.3%

7
Others - 1.3%

Question 4

What is the overall incidence of anaphylaxis to muscle relaxants

Answer 4

1 in 6500
Most common because they are ‘functionally divalent’ meaning they can crosslink cell surface IgE –> H release from MAst cells without having to bind to haptens or large carrier molecules

Question 5

How is it possible that anaphylaxis to NMB agents can occur on 1st exposure

Answer 5

Many over-the-counter drugs, cosmetics and food products contain tertiary or quaternary ammonium ions that can sensitize patients to muscle relaxants resulting in anaphylaxis in these patients on first exposure

Question 6

If a patient has anaphylaxis to a benzylquinolinium, what percentage of these patients will also have anaphylaxis to an aminosteroid?

Answer 6

75% of patients display cross-reactivity between these two muscle relaxant groups

Question 7

Are atracurium and mivacurium commonly associated with allergic anaphylaxis

Answer 7

No. They are associated with non-allergic anaphylaxis in which the release of mediators (especially histamine) from mast cells can mimic the presentation of the presentation produced by allergic anaphylaxis

Question 8

Which antibiotics most commonly cause anaphylaxis

Answer 8

1. Penicillin
2. Cephalosporin

Together these cause 70% of anaphylaxis

Question 9

Is it safe to administer propofol to egg allergic patients

Answer 9

Propofol is currently formulated in intralipid containing soybean oil, egg lecithin and glycerol. Current evidence indicates that it is safe to administer propofol to egg-allergic patients. The egg lecithin component of propofol is a highly purified egg yolk component and skin tests with propofol and its intralipid solvent were negative in patients with known egg allergy.

Question 10

What is the incidence of anaphylaxis for thiopental and for propofol

Answer 10

Thiopental - 1 in 30 000

Propofol 1 in 60 000

Question 11

Are there reports of anaphylactic reactions to volatile agents?

Answer 11

None

However: Very rare incidents of immune mediated hepatitis with Halothane, enflurane, isoflurane and desflurane

Question 12

Describe immune disturbance related to the opioids

Answer 12

Morphine: non-immunological histamine release

Fentanyl - does not cause non-immunological histamine release

Question 13

Which clinical conditions are often confused with true anaphylactic reactions to local anaesthetics?

Answer 13

A. Vaso-vagal reactions
B. Effects of adrenaline
C. ‘Panic attacks’
D. Systemic toxic effects of local anaesthetics
E. Reaction related to the additives in local

Question 14

What type of local anaesthetic is more likely to cause anaphylaxis and why?

Answer 14

Ester LA are hydrolysed to PABA (para-aminobenzoic acid) which is a known allergen

True anaphylactic reactions are either from PABA or from a preservative: methylparaben

Question 15

A drug allergy to which group of drugs requires avoidance of ester LAs and why

Answer 15

Patients with a sulphonamide allergy should not be prescribed ester LAs as the PABA molecule is structurally very similar to the sulphonamide molecule

Question 16

What is the name of the tree from which natural rubber latex is derived?

Answer 16

Hevea Brasiliensis - milky white fluid

Question 17

When does anaphylaxis to Natural Rubber Latex occur and how is the patient exposed?

Answer 17

Mucous membranes/surgical wounds/parenteral injection exposure

Usually occurs 1 hour after exposure

Question 18

Describe the different types of latex reactions

Answer 18

1. Type 1 hypersensitivity reaction
   - Specific IgE to NRL proteins (most severe but least frequent)
2. Delayed type IV hypersensitivity reaction (contact dermatitis)
   - Occurs 24 - 48 hours after repeated skin or mucosal contact (t-cell mediated and non-lifethreatening)
3. Non-immune mediated itching, irritation and blistering at the site of contact due to powder in the gloves, disinfectants and sweating

Question 19

What can cause anaphylaxis during breast surgery? AN in what % of patients experience allergic reactions to this aspect of breast surgery?

Answer 19

Isosulfan blue dye used for lymphatic mapping and sentinal LN biopsy.

2% of patients exposed to blue dye have an allergic reaction

Question 20

Apart from some colloids, where else is gelatin found and why is it relevant to anaesthesia

Answer 20

Found in colloids, sweets and vaccines

Can cause allergy

Question 21

In which patients should all beta lactam antibiotics be avoided?

Answer 21

Severe allergic reaction to a beta lactam antibiotic

Question 22

In which patients can 3rd generation cephalosporins be used as a substitute

Answer 22

Itchy rash must be further investigated for possible penicillin allergy. Penicillins and other beta lactam antibiotics must be avoided although 3rd generation cephalosporin drugs may be used where indicated. (No mucosal involvement and no non-itchy rash)

Question 23

Which antibiotics contain a beta lactam ring

Answer 23

PENICILLINS
CEPHALOSPORINS
CARBAPENEMS

Benzylpenicillin, phenoxymethylpenicillin
Flucloxacillin
Amoxicillin
Ampicillin
Co-amoxiclav
Pip-Taz
Cephalosporins
Carbapenems (including aztreonam)

Question 24

Can the risk of perioperative anaphylaxis be mitigated through screening tests?

Answer 24

There is no test that can predict anaphylaxis

There is a very low positive predictive value for IgE specific assays and skin tests.

Question 25

What are the goals of allergy centre referral

Answer 25

Determine the cause
Detect other drugs which may produce similar event
Determine drugs safe to use in future anaesthetics

Question 26

Which patients are at increased risk of anaphylaxis during surgery.

what actions should be taken if there is increased risk

Answer 26

1. Females
2. History of atopy
3. Previous anaphylaxis
4. Unexplained reaction to previous anaesthetic: (hypotension/bronchospasm/urticarial rash/angioedema)
5. Patients who say they are allergic to muscle relaxants or local anaesthetics
6. Latex allergy

Elective –> refer patient to allergy centre

Emergency –>

• Consider RA,
• If GA required: no NMB and no Latex,
• Avoid drugs that cause H release (morphine/atracurium/gelatins)
• Pretreatment with Hydrocortisone H antagonists
• Prepare to treat anaphylaxis

Question 27

Is atopy a risk factor for the development of antibodies to anaesthetic agents

Answer 27

No evidence. However, a history of atopy does increase risk of latex allergy. Furthermore, these patients are likely to be at higher risk for histamine release in agents that bring about such effects: when atracurium, morphine, propofol, gelatin are injected rapidly.

Question 28

Give some examples of household items that contain latex

Answer 28

Household gloves, balloons, contraceptives, hot water bottles, erasers, rubber bands/balls, elastic waistbands/underwear.

If NRL allergy suspected –> send for testing before elective surgery

Question 29

What should be done if a NRL allerguc patient cannot be positioned first on the operating list

Answer 29

A risk assessment must be undertaken to ensure that the area has had sufficient time to remove NRL particles from the air depending on the number of air changes within the room.

Anaesthesia and recovery should both take place in the operating theatre.

Question 30

In what percentage of patients with an allergy to a specific muscle relaxant will experience anaphylaxis to a different class of muscle relaxant?

Answer 30

75%

Question 31

How do allergic reactions to chlorhexidine normally present

Answer 31

CVS and cutaneous