analphylactic shock Flashcards
signs and symptoms of anaphylaxis
swelling of conjunctiva runny nose swelling of lips tongue throat fast/slow HR low bp hives itchiness swelling pelvic pain light headed loss of consciousness confusion headache anxiety SOB wheezes hoarseness pain with swallowing cough crampy abdo pain diarrhea vomiting loss of bladder control
what is anaphylaxis
acute
type 1 hypersensitivity rn - systemic
life threatening
IgE mediated response to allergen throughout the body
IgE response
important against parasitic infections
normal lymphocyte activation
antigen binds to surface of IgM on lymphocytes
stimulate prolif and secretion of Ab
Ab is IgM and then IgG as response progresses
lymphocyte activatation in Type 1 hypersensitivity
activation of CD4+ T helper cells (TH2)
IgE production
IgE binds to IgE receptors on mast cells
subsequent stimulation of mast cells by exposure = anaphylactic response
allergen
antigen that causes an allergic type of IgE mediated response
mast cells
widely distributed in epithelial mucosae - resp and intestinal and connective tissue - under the skin
contain granules with histamine and leukotrienes
secreted following antigen binding to IgE
action of inflammatory mediators
act on bv and sm
in connective tissue histamine = dilation of vessels = blood flow to surface = fluid move out of blood - oedema
mucosae - constriction of airways and sm in intestines
net effect depends on if local/systemic
skin allergy
stim of connective tissue mast cells = vasodilation = red skin rash and oedema = raised appearance
rash called urticaria - from nettles
use of localised skin reaction
allergy testing
allergens injected by pin prick to see if have wheal and flare reaction
substances that cause skin allergies
animal hair
proteins in natural latex
chemicals
substances in insect and plant stings
hay fever and asthma
allergen inhaled
principle site of action - mucosal mast cells in resp system
if in nasal passage = oedema = irritation = mucous secretion - allergic rhinitis
if reac bronchioles - contraction of sm = reduced diameter, inf and increased mucous - asthma - difficulty breathing in and mainly out
substances causing hay fever and asthma
pollen
faeces of dust mites
proteins from animal hairs
food allergy
ingested
mucosal mast cells in GI tract
stimulation of sm = vomiting and diarrhoea
if it can be absorbed and passed to the blood stream - rash and itching
substances that cause food allergies
peanuts other nuts and legumes - soya shellfish milk eggs wheat
anaphylaxis
systemic result to allergen cause immediate response throughout body not common potentially fatal medical emergency dilation of peripheral bv = rash and oedema and drop in bp affectiung organ function - shock constriction fo bronchi = difficulty breathing increase in resp rate and HR nausea, ab cramps, diarrhoea
treatment of anaphylaxis
emergency treatment - aimed at hypotension and underlying inf
patient laid down with feet raised - improve blood flow to head and trunk
adrenaline constrict peripheral vessels - redirect blood flow to organs
IV drip - control BP
antihistamines and antiinf corticosteroids
if breathing problems persist - oxygen and bronchodilators needed by inhaler
requirement for substances to cause anaphylaxis
substances have to eb able to pass freely through the body
substances that can cause anaphylaxis
penicillin - especially if IV
local anesthetics and x ray contrast agents
venom in bee/wasp stings
peanuts - allergen can be absorbed fast enough to cause systemic effects
long term treatment of anaphylaxis
avoid allergen
adrenaline in self injection pen for use in emergency
cause of anaphylaxis
can have a genetic predisposition
sensitisation
1st meeting with allergen = no clinical effect
2nd = clinical effect
process of immune response in 1st exposure
APC start reaction
present antigen to T helper cell
naïve T helper turns to primed Th
stimulatory molecules T4, 5 , 10 stimulate type 2 Th
maturation of type 2
can produce interleukins - inf response amplified
induce maturation of other molecules eg Ig 4 - B cells, Ig5 - eosinophils - degranulation
B cell produce eosinophils
go on surface of mast cells bound to FcE receptors - multiple bonds - sensitisation
what determines the type of Th cells
the proteins around it
