Causes and Treatment
Anaphylaxis due to anaesthetic drugs has an incidence of about 1 in 10-20 000.
This translates into about 55 suspected anaphylactic reactions per year in the UK. Data from France suggests that neuromuscular blocking drugs are the most commonly-involved group.
The triad of cardiovascular collapse, bronchospasm and widespead erythema are the most common features.
However, these may not be the only or presenting features. Others include: oedema, desaturation, cough and urticaria.
The treatment of anaphylaxis has two stages:
Initial Management
The initial management should follow these steps:
1. Stop administration of all agents likely to have caused the anaphylaxis.
2. Call for help.
3. Maintain airway, give 100% oxygen and lie patient flat with legs elevated.
4. Give adrenaline. This may be given either IV or IM.
- IV: 50-100 μg titrated to effect
- IM: 0.5-1 mg repeated as required after 10 minutes
Never give undiluted adrenaline 1:1000 IV. It is not possible to give the chosen dose accurately.
Secondary Management
- IV fluids: The exact nature of the fluid is not important in the first instance. Volume is the key. But remember large volumes of 5% dextrose do not remain in the circulation for long and that colloids may cause anaphylaxis
- Antihistamine: Chlorphenamine, 10 mg IV, may be helpful and is unlikely to be harmful
- Steroids: Hydrocortisone, 100 mg IV, should be administered after severe attacks to help prevent late sequelae. This is of particular importance for asthmatics if they have been treated with corticosteroids previously