Immunology Flashcards
Anaphylaxis definition?
Sudden onset and rapid progression of ABC symptoms
1. Airway = swelling of throat and tongue –> hoarse voice and stridor
2. Breathing = wheeze and SOB
3. Circulation = hypotension and tachycardia
Anaphylaxis adrenaline doses?
- <6m = 100-150 mcg (0.1-0.15ml 1 in 1000)
- 6m-6y = 150 mcg (0.15ml 1 in 1000)
- 6-12y = 300mcg (0.3ml 1 in 1000)
- > 12 = 500mcg (0.5ml 1 in 1000)
How often can adrenaline be repeated?
Every 5m
Refractory anaphylaxis?
- Respiratory and/or cardiovascular problems persist despite 2 doses of IM adrenaline
- IV fluids should be given for shock
- Consider IV Adrenaline infusion
Management of anaphylaxis following stabilisation?
- Non-sedating oral antihistamine
- Serum tryptase levels (elevated up to 12 hours)
- Referral to specialist allergy clinic
- Adrenaline injector given (should be prescribed 2, training provided on how to use it)
Biphasic reaction to anaphylaxis %?
In 20%
Risk-stratified approach to anaphylaxis discharge?
- Fast-track (after 2h symptoms resolution) = good response to single dose of adrenaline, given epipen, adequate supervision post discharge
- Minimum 6h after symptom resolution = 2 doses IM adrenaline needed, previous biphasic reaction
- Minimum 12h after symptoms resolution? = >2 IM adrenaline, severe asthma, possibility ongoing reaction, late at night, emergency access difficult area, observation for at least 12h following symptoms resolution
3 allergy tests?
- Skin prick tests
- Radioallergosorbent test (RAST)
- Skin patch testing
Skin prick test mushkies?
Most commonly used test as easy to perform and inexpensive. Drops of diluted allergen are placed on the skin after which the skin is pierced using a needle. A large number of allergens can be tested in one session. Normally includes a histamine (positive) and sterile water (negative) control. A wheal will typically develop if a patient has an allergy. Can be interpreted after 15 minutes. Useful for food allergies and also pollen.
RAST mushkies?
- Determines the amount of IgE that reacts specifically with suspected or known allergens, for example IgE to egg protein. Results are given in grades from 0 (negative) to 6 (strongly positive)
- Useful for food allergies, inhaled allergens (e.g. Pollen) and wasp/bee venom
- Blood tests may be used when skin prick tests are not suitable, for example if there is extensive eczema or if the patient is taking antihistamines
Skin patch testing mushkies?
Useful for contact dermatitis. Around 30-40 allergens are placed on the back. Irritants may also be tested for. The patches are removed 48 hours later with the results being read by a dermatologist after a further 48 hours
