Anaphylaxis

Question 1

What is anaphylaxis?

Answer 1

Serious systemic hypersensitivity reaction that is usually rapid in onset and may cause death

Question 2

What is the time to death caused by different triggers?

Answer 2

• food- 30 min
• insect stings- 10-15 min
• IV meds- 5 min

Question 3

What three criteria suggest anaphylaxis?

Answer 3

1. sudden onset and rapid progression of symptoms
2. life-threatening airway and/or breathing/circulation problem
3. skin and/or mucosal changes

Question 4

What percentage of anaphylaxis patient sdo not have skin/mucosal changes

Answer 4

20%

Question 5

What is stidor?

Answer 5

A high pitched inspiratory noise caused by airway blockade

Question 6

What other life-threatening conditions can mimic anaphylaxis?

Answer 6

• life threatening asthma
• septic shock

Question 7

What conditions that do not respond to adrenaline can mimic anaphylaxis?

Answer 7

• inducible laryngeal obstruction
• ACE inhibitor-induced angioedema

Question 8

What non life-threatening conditions that respond to simple measures can mimic anaphylaxis?

Answer 8

faint
panic attack
breath holding episode
idiopathic urticartia/angioedema

Question 9

What must a patient not do if suffering anaphylaxis

Answer 9

Walk/stand
sit-up suddenly

Question 10

What is the role of adrenaline in anaphylaxis?

Answer 10

alpha receptor agonist
* reverses peripheral vasodilation and oedema

beta receptor activity
* dilates the bronchial airways
* increases the force of myocardial contrction
* suppresses histamine and leukotriene release

Question 11

What is the dose of adrenaline in adults?

Answer 11

0.5mg (0.5mL of 1:1000)

Question 12

What is the best site for administration of IM adrenaline?

Answer 12

anterolateral aspect of the middle third of the thigh

Question 13

What is refractory anaphylaxis?

Answer 13

Does not respond to 2 doses of IM adrenaline

Question 14

What can IV adrenaline cause?

Answer 14

• hypertension
• tachycardia
• arrhythmias
• myocardial ischaemia

Question 15

What might be effective as an adjunct to treat upper airways obstruction caused by laryngeal oedema?

Answer 15

Nebulised adrenaline
5mL of 1mg ml (1:1000)

only after treatment with IM (or IV) adrenaline, not as an alternative

Question 16

What is the special test to help confirm a diagnosis of anaphylaxis?

Answer 16

Measurement of mast cell tryptast

Question 17

How should mast cell tryptase sampling be done?

Answer 17

a) minimum: one sample within 2h (but no later than 4)
b) ideally three time samples
- as soon as feasible after resuscitation has started
- second sample at 1-2 h
- third sample at 24h
c) either serum or plasma samples
d) record the time of each sample
e) specimens are stable up to 2 days at room temp

Question 18

In refractory anaphylaxis how ofen should IM adrenaline be given?

Answer 18

every 5 minutes until an infusion has been started

Question 19

What is the dose of an adrenaline infusion?

Answer 19

1mg (1mL of 1mg/ml (1:1000)) adrenaline in 100ml of 0.9% NaCl

give 0.5-1ml/kg/hr and titrate according to response

Question 20

What can you NOT do with an adrenaline infusion

Answer 20

• piggy back on another infusion line
• infuse on the same side as a BP cuff

Question 21

What does hypertension during adrenaline infusion suggest?

Answer 21

Overdose

Question 22

What should be done if anaphylaxis is resistant to an adrenaline infusion?

Answer 22

Consideration of a second vasopressor
- noradrenaline, vasopressin or metraminol
- consider glucagon in patients on beta-blockers