Urticaria and itch Flashcards
causes of urticaria
Allergic: type 1 IgE
Non-allergic: chemically mediated - salicylates…
Physical: dermographism, delayed pressure, vibration, aquagenic, solar, cold, cholinergic
Autoimmune
what is urticaria
dermal oedema
transient eruption of erythematous and oedematous swellings of the dermis usually associated with itching
how long do individual lesions last in urticaria
<24 hours
what are the categories of urticaria
acute <6weeks
chronic >6weeks
what is angioedema
transient (24-48h) swellings in the deeper dermal, subcutaneous and submucosal tissues
name of lesion in urticaria
wheal
chemical mediators of urticaria
histamine heparin prostaglandins leukotrienes proteases
causes of angioedema
same as causes of urticaria PLUS:
C1 esterase inhibitor deficiency
ACEI
management of urticaria and angioedema
treat underlying cause
suppression - antihistamines, leukotriene antagonists, serotonin antagonists
definition of anaphylaxis
acute angioedema often with urticaria and with respiratory compromise and/or hypotension
management of anaphylaxis
ABCDE
IM adrenaline 1:1000
(IV carries risk of tachyarrhythmias)
IV antihistamine, IV hydrocortisone
what is pruritis
itch
causes of itch
pruritoceptive
neuropathic
neurogenic
psychogenic
is stinging nettle urticaria an allergic reaction
no
it is as a result of mast cell degranulation and histamine release
describe a wheal
paler centre - from papillary dermal oedema
erythematous edges
normal epidermal markings are present
