Anaphylaxis Flashcards
What is anaphylaxis?
Serious systemic hypersensitivity reaction that is usually rapid in onset and may cause death
What is the time to death caused by different triggers?
- food- 30 min
- insect stings- 10-15 min
- IV meds- 5 min
What three criteria suggest anaphylaxis?
- sudden onset and rapid progression of symptoms
- life-threatening airway and/or breathing/circulation problem
- skin and/or mucosal changes
What percentage of anaphylaxis patient sdo not have skin/mucosal changes
20%
What is stidor?
A high pitched inspiratory noise caused by airway blockade
What other life-threatening conditions can mimic anaphylaxis?
- life threatening asthma
- septic shock
What conditions that do not respond to adrenaline can mimic anaphylaxis?
- inducible laryngeal obstruction
- ACE inhibitor-induced angioedema
What non life-threatening conditions that respond to simple measures can mimic anaphylaxis?
faint
panic attack
breath holding episode
idiopathic urticartia/angioedema
What must a patient not do if suffering anaphylaxis
Walk/stand
sit-up suddenly
What is the role of adrenaline in anaphylaxis?
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
What is the dose of adrenaline in adults?
0.5mg (0.5mL of 1:1000)
What is the best site for administration of IM adrenaline?
anterolateral aspect of the middle third of the thigh
What is refractory anaphylaxis?
Does not respond to 2 doses of IM adrenaline
What can IV adrenaline cause?
- hypertension
- tachycardia
- arrhythmias
- myocardial ischaemia
What might be effective as an adjunct to treat upper airways obstruction caused by laryngeal oedema?
Nebulised adrenaline
5mL of 1mg ml (1:1000)
only after treatment with IM (or IV) adrenaline, not as an alternative
What is the special test to help confirm a diagnosis of anaphylaxis?
Measurement of mast cell tryptast
How should mast cell tryptase sampling be done?
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
In refractory anaphylaxis how ofen should IM adrenaline be given?
every 5 minutes until an infusion has been started
What is the dose of an adrenaline infusion?
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
What can you NOT do with an adrenaline infusion
- piggy back on another infusion line
- infuse on the same side as a BP cuff
What does hypertension during adrenaline infusion suggest?
Overdose
What should be done if anaphylaxis is resistant to an adrenaline infusion?
Consideration of a second vasopressor
- noradrenaline, vasopressin or metraminol
- consider glucagon in patients on beta-blockers
