Urticaria (hives)
Treatment of anaphylaxis
assess ABCs! call 911! first-line: epinephrine, IV fluids and oxygen
Angioedema
cause by same pathogenic mechanisms of urticaria, but pathology is in the deep dermis with subcutaneous swelling - commonly affects face or extremity (tongue, pharnyx, larynx, bowels -> hoarseness, dyspnea and GI symptoms) - may be painful or burning but NOT pruritic - may last several days
Diagnosis of urticaria
clinical dx IgE receptor Ab testin gis possible in chronic disease, but often does not change management most resolve in 1-3 years
Most common form of physical urticaria
dermatographism - sharply localized edema or wheal within seconds to minutes after skin has been rubbed
Treatment of urticaria
first line: 1st-gen. oral H1 antihistamines (ex. hydroxyzine or diphenhydramine) = sedating 2nd gen. H1 antihistamines (ex. loratidine, cetirizine or fexofenadine) = less sedating
Causes of chronic urticaria
idiopathic (>50%), physical causes (pressure, cold, heat, water, sunlight, vibration, exercise), autoimmune (IgE receptor Ab), infection, ingestion, medication cholinergic urticaria = triggered by heat or emotion
Causes of acute urticaria
idiopathic, post-infectious, food reaction, drug or infusion reaction note: detergents and common contact allergens are not triggers of urticaria (latex is an exception)
Pathophysiology or urticaria
mast cell degranulation -> histamine release -> binds H1 & H2 receptors -> arteriolar dilation, venous constriction, inc capillary permeability immunologic (antigen binds IgE on mast cell surface) or non-immunologic (via pharmacologic or physical mechanism)
Typical time course
most cases are acute (<6 weeks), but some are chronic (>6 weeks) ***indviduals papules last <12 hrs
Cardinal symptom of urticaria
pruritus
Anaphylaxis
serious allergic reaction that is rapid in onset and may cause death may have no skin lesions or may have angioedema and/or urticaria ask about: chest tightness, difficult breathing, hoarse voice, throat tightness, nausea, vomiting, abd pain, lightheadedness
Wheals
transient, circumscribed, elevated papules or plaques, often with erythematous borders and pale centers
What is urticaria (aka hives)?
vascular reaction of skin characterized by wheals surrounded by blanchable red halo or flare (erythema) indviduals papules last <12 hrs
