Anaphylaxis

Question 1

What is the estimated incidence of perioperative anaphylaxis according to NAP6?

Answer 1

Approximately 1 in 10,000 anaesthetics.

Question 2

Which agents are most commonly implicated in perioperative anaphylaxis?

Answer 2

Antibiotics (48%) and neuromuscular blocking agents (NMBAs) (25%).

Question 3

What percentage of antibiotic-induced anaphylaxis cases were attributed to teicoplanin?

Answer 3

38% of antibiotic-induced cases.

Question 4

Which NMBA has the highest incidence of anaphylaxis per 100,000 exposures?

Answer 4

Succinylcholine: 11.1 per 100,000 exposures.

Question 5

What is the Ring and Messmer severity grading scale used for?

Answer 5

Grading severity of anaphylaxis from I (mild) to IV (cardiac arrest).

Question 6

What are common clinical presentations of perioperative anaphylaxis?

Answer 6

Hypotension, bronchospasm, tachycardia.

Question 7

What is the cornerstone of management for perioperative anaphylaxis?

Answer 7

Adrenaline and IV fluid resuscitation.

Question 8

How is the diagnosis of perioperative anaphylaxis confirmed?

Answer 8

Clinical signs, raised tryptase, and allergy testing.

Question 9

What is the mortality rate associated with perioperative anaphylaxis in the UK?

Answer 9

Approximately 3.8%.

Question 10

Which antiseptic has been increasingly implicated in perioperative anaphylaxis?

What percentage of anaphylaxis does this account for?

Answer 10

Chlorhexidine - 10%

Question 11

What is the typical onset time for anaphylaxis due to IV agents?

Answer 11

Usually within minutes of administration.

Question 12

How does succinylcholine-induced anaphylaxis differ clinically?

Answer 12

More likely to present with bronchospasm.

Question 13

What is the role of serum tryptase in anaphylaxis diagnosis?

Answer 13

Supports diagnosis when elevated after a reaction.

Question 14

What is the incidence of chlorhexidine-induced anaphylaxis per 100,000 exposures?

Answer 14

0.78 per 100,000 exposures.

Question 15

What percentage of cases were reported to the MHRA Yellow Card Scheme?

Answer 15

Only 24%.

Question 16

What factors are associated with poor anaphylaxis outcomes?

Answer 16

Higher ASA, obesity, ACEIs, beta-blockers.

Question 17

What is the value of a ‘test dose’ of antibiotics in anaphylaxis prevention?

Answer 17

Unreliable; some reactions occurred with test dose.

Question 18

What is the first-line treatment for bronchospasm in anaphylaxis?

Answer 18

Adrenaline.

Question 19

Why is skin testing important after a reaction?

Answer 19

To identify the causative agent for future avoidance.
Low risk of anaphylaxis but the test may trigger

Question 20

What is the timing for tryptase sampling?

Answer 20

Immediately, at 1–2 hours, and a baseline ≥24 hrs later.

Question 21

What defines a significant rise in serum tryptase?

Answer 21

Peak ≥ (1.2 × baseline) + 2 µg/L.

Question 22

How do beta-blockers affect anaphylaxis?

Answer 22

Worsen severity of anaphylaxis, may exacerbate bronchospasm and reduce adrenaline efficacy.

Higher mortality rate - 60% of fatalites were taking beta-blockers (NAP 6)

Question 23

What can be used in beta-blocked patients with anaphylaxis?

Answer 23

Glucagon.

Question 24

What was the most common clinical sign reported in NAP6?

Answer 24

Hypotension (>95%).

Question 25

When should antibiotics ideally be given perioperatively?

Answer 25

Pre-induction with full monitoring.

Question 26

Which NMBA had the lowest confirmed IgE-mediated reaction rate in NAP6?

Answer 26

Atracurium.

Question 27

What is the initial IV adrenaline dose in severe perioperative anaphylaxis?

Answer 27

50–100 mcg IV bolus, titrated to effect.

Question 28

When is vasopressin or noradrenaline considered in anaphylaxis?

Answer 28

If unresponsive to adrenaline and fluids.

Question 29

What hypersensitivity type is perioperative anaphylaxis?

Answer 29

Type I (IgE-mediated).

Question 30

What are non-IgE-mediated anaphylactoid reactions?

Answer 30

Clinically similar, but not immune-mediated (e.g., opioids).

Question 31

What proportion of cases involved multiple suspected agents?

Answer 31

~20%.

Question 32

What is the gold standard test for identifying the causative agent?

Answer 32

Skin testing (SPT or intradermal).

Question 33

What concentration is non-irritant for intradermal rocuronium testing?

Answer 33

0.0004 mg/mL.

Question 34

How should NMBAs be used after suspected NMBA anaphylaxis?

Answer 34

Avoid entire class unless tested and cleared.

Question 35

What precautions should be taken with chlorhexidine in allergic patients?

Answer 35

Avoid all forms, label clearly, and substitute.

Question 36

Why is latex anaphylaxis now rare?

Answer 36

Shift to latex-free equipment in theatres.

Question 37

What is the role of specific IgE testing?

Answer 37

Limited sensitivity; adjunct to skin testing.

Question 38

What is a biphasic reaction?

Answer 38

Recurrence of symptoms after resolution, without re-exposure.

Question 39

How can biphasic reactions be mitigated?

Answer 39

Prolonged monitoring, cautious steroid use.

Question 40

What percentage of anaphylaxis cases required CPR (NAP6)?

Answer 40

~10%.

Question 41

What factors improve outcomes in perioperative anaphylaxis?

Answer 41

Prompt diagnosis, adrenaline, fluids, and team response.

Question 42

What were common delays identified in NAP6?

Answer 42

Delayed recognition and adrenaline administration.

Question 43

What role does capnography play in intraoperative anaphylaxis?

Answer 43

Drop in EtCO₂ suggests reduced perfusion/output.

Question 44

When should patients be referred to allergy services?

Answer 44

After any suspected perioperative anaphylaxis.

Question 45

What documentation is essential post-anaphylaxis?

Answer 45

Tryptase samples, anaesthetic record, DATIX, MHRA Yellow Card.

Question 46

What systemic changes did NAP6 recommend?

Answer 46

National allergy services, training, and reporting improvements.

Question 47

What is the role of antihistamines and steroids?

Answer 47

Adjuncts only; not lifesaving or first-line.

Question 48

What is the 'Golden Hour' in anaphylaxis?

Answer 48

Critical first hour where intervention is most effective.

Question 49

How can perioperative anaphylaxis risk be reduced pre-op?

Answer 49

Allergy history, cautious drug choice, avoiding triggers.

Question 50

What is the importance of multidisciplinary simulation training for anaphylaxis?

Answer 50

Improves recognition, communication, and timely intervention.