Anaphylaxis

Question 1

What is anaphylaxis.

Answer 1

Type 1 IgE mediated hypersensitivity reaction.
Release of histamine and other agents causes:
Capillary leak.
Wheeze.
Cyanosis.
Oedema (larynx, lids, tongue, lips).
Urticaria.

Question 2

Who is most at risk for anaphylaxis.

Answer 2

Atopic individuals.

Question 3

What does an anaphylactoid reaction result from. (2)

Answer 3

Results from direct release of mediators from inflammatory cells, without involving antibodies.
Usually in response to a drug (eg acetylcystine).

Question 4

What are some precipitants for anaphylactic shock. (8)

Answer 4

Drugs (penicillin, contrast media in radiology). 
Latex. 
Strawberries. 
Stings. 
Eggs. 
Fish. 
Peanuts. 
Semen (rare).

Question 5

What are the clinical manifestations of anaphylactic shock. (11)

Answer 5

Itching. 
Sweating. 
Diarrhoea and vomiting. 
Erythema. 
Urticaria. 
Oedema. 
Wheeze. 
Laryngeal obstruction. 
Cyanosis. 
Tachycardia. 
Hypotension.

Question 6

What other conditions may mimic the clinical features of anaphylactic shock. (4)

Answer 6

Carcinoid.
Phaeochromocytoma.
Systemic mastocytosis.
Hereditary angioedema.

Question 7

How would you treat anaphylaxis. (5)

Answer 7

ABCDE.
Remove the cause: raising the feet may help to restore circulation.
Give adrenaline IM0.5mg (repeat every 5mins, as needed guided by BP, HR and RR).
Chlorphenamine 10mg IV and hydrocortisone 200mg IV.
IVI (titrate against BP).
If there is a wheeze, treat for asthma.
If still hypotensive, admission to ITU and IVI adrenaline may be needed with aminophylline and nebulized salbutamol .