Urticaria and Itch Flashcards
What is urticaria?
A transient (individual lesions last <24 hours) eruption of erythematous and oedematous swellings of the dermis, usually associated with itching
What is the time cut off between acute and chronic urticaria?
6 weeks (less thanks = acute, more than = chronic)
Where is histamine released from and what triggers it?
Mast cells in the skin and tissues in response to the binding of allergen-bound IgE antibodies to high-affinity cell surface receptors
Name an inherited cause of angioedema?
C1 esterase inhibitor deficiency
Name an acquired cause of angioedema?
Ace inhibitors
What are the steps in the management of anaphylaxis?
- Ensure airway adequate and, where suspected food allergy, no possibly-responsible food still in mouth
- At same time, give INTRAMUSCULAR epinephrine (adrenaline) 0.5 to 1 mL of 1:1000 dilution. Repeat at 15 minute intervals until improvement occurs.
- Give high concentration oxygen if cyanosed
- Give IV antihistamine and 200mg IV hydrocortisone
- If recovering, but still shocked (systolic BP remaining low) consider IV saline
- If it becomes clear that likely cause was accidental peanut ingestion by known peanut-allergic patient, consider oral activated charcoal
What are the steps in the management of anaphylaxis but in a simpler way?
- Airway adequate
- IM Epinephrine
- Oxygen if cyanosed
- IV antihistamine and 200mg IV hydrocortisone
- If still shocked give IV saline
- Oral charcoal if peanut allergy was cause
What are the 4 causes of itch?
Pruritoceptive
Neuropathic
Neurogenic
Psychogenic
What is pruritoceptive itch?
Something (usually inflammation or dryness) in skin that triggers itch
What is neuropathic itch?
Damage of any sort to central or peripheral nerves causing itch
What is neurogenic itch?
No evident damage in CNS, but itch caused by, e.g., opiate effects on CNS receptors
What is psychogenic itch?
Psychological causes with no (currently detectable) CNS damage, e.g. in parasitophobia
