Anaphylaxis Flashcards
(22 cards)
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
