Anaphylaxis
| 2021 changes: lie them down, IM adrenaline, refractory anaphylaxis algorithm added | |
|---|---|
| History | Food allergens most likely to cause airway problems? |
| Examination | 1. Sudden onset 2. Life-threatening Airway, Breathing or Circulation problem 3. after exposure to an allergen > notably, does NOT require skin changes |
| Diagnostic investigations | TREAT FIRST, then Mast cell tryptase |
| Differentials | Angioedema |
| Management | LIE DOWN. IM adrenaline, adrenaline, adrenaline!!!! - IV only for peri-operative or critical care context - in cardiac arrest, use normal arrest doses of adrenaline (1mg = 10ml 1:10000 IV) Generous fluid resuscitation Notorious biphasic reaction - ↑ risk with: - More severe initial presentation - Initial reaction requiring more than one dose of adrenaline - Delay in adrenaline administration (>30-60 min from symptom onset) - History of a previous biphasic reaction |
INTRAMUSCULAR 1:1000 doses
| Age | Dose | Volume of 1:1000 adrenaline IM |
|---|---|---|
| <6 months | 100-150mcg | 0.1 - 0.15ml |
| 6m- 6y | 150mcg | 0.15ml |
| 6-12y | 300mcg | 0.3ml |
| >12y | 500mcg | 0.5ml |
pathogenesis
Histamine release from mast cells and basophils
refractory anaphylaxis
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IM adrenaline every 5 min until IV adrenaline running (!)
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Get ICU on board
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Dedicated IV/IO access
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Peripheral low dose adrenaline = 1mg (1ml of 1:1000) in 100ml 0.9%% sodium chloride
- no other infusions in this line
- no BP cuff on this limb
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Start at 0.5ml/kg/h and titrate to response
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A/B: oxygenation over intubation
- consider neb adrenaline
- bronchospasm: neb/IV salbutamol; sevoflurane to induce
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Refractory hypotension?
- add noradrenaline, metaraminol, vasopressin
- glucagon for beta blocked patients?