Anaphylaxis

Question 1

Definition of anaphalaxis

Answer 1

an acute, potentially life-threatening multisystem syndrome caused by the sudden release of mast cell mediators into the systemic circulation

most often IgE mdiated reaction to foods / drugs / insect stings

Question 2

3 meds in anaphalaxis

Answer 2

adrenaline
antihistamine
hydocortisone

Question 3

presentation of anaphalaxis

Answer 3

onset is almost always within 2hrs
angiodema- soft tissue swelling (lips, tongue, larynx)

widespread urticaria
giant hives (raised rash, erythema, central pallor to the raised region, small little dots or large patches)

Question 4

signs and symptoms (systems)

Answer 4

CNS : lightheaded, LOC, confusion, headche, anxiety

RESP: SOB, wheeze, hoarseness, pain on swallowing, cough

GI: crampy abdo pain, diarrhoea, vomiting

loss of bladder control
pelvic pain

SKIN : hives, itchy, flushing

CVS: fast/slow HR, low BP

swelling of lips, tongue, throat. swelling of the conjunctiva. runny nose.

Question 5

diagnosis likely if all 3 present

Answer 5

1. sudden onset and rapidly progressive symptoms
2. life threatening airway + breathing + circulatory
3. skin + mucosal changes
   exposure to suspected allergen in 1-2hrs

Question 6

airway anaphalaxis

Answer 6

significant tongue/throat swelling
stridor
hoarseness

Question 7

breathing anaphylaxis

Answer 7

SOB, wheeze, hypoxia, accessory muscle use, cyanosis, confusion, respiratory arrest

Question 8

circulatoion

Answer 8

pale, clammy, shock, hypotension, tachycardia, decreased conscious level, MI/ECG changes, cardiac arrest

Question 9

co factors that can influence the severity of anaphylaxis

Answer 9

asthma/other resp disease
infection
CVS disease
b blockers
alpha blockers
ACEi (bradykinin, angiodema)
NSAIDs (can cause angiodema)
alcohol
exercise

Question 10

common triggers of anyphalaxis

Answer 10

eggs, milk, legumes (peanuts, soy beans) tree nuts (walnut, almond, cashew, hazelnut, brazil nut), shellfish, latex, venom (bee/wasp), drugs (penicillin)

*anything with a protein substance

Question 11

MOA of type I hypersensitvity

Answer 11

two stages

1. first exposure (sensitisation)

first encounter the allergen that you subsequently become allergic to. takes 4-6 weeks to happen. APC take it to Th cells and B cells. interact and make plasma cells= IgE (specific to the allergen)
IgE adheres to the surface on mast cell surfaces

*don’t have any significant symptoms during this time

2. re-exposure
   protein goes directly to the mast cell (allergen binds to IgE) degranulation. release of histamine, leukotrienes etc.

Question 12

Anaphalaxis management resucitation counsil UK

Answer 12

A-E
call emergency / support from staff.
lie flat and raise legs to help venous return

early administration of IM adrenaline 0.15-0.5mg 1:1000 (depends on age) deliver to anterolateral thigh 1st third

observation of airway
o2 and fluid challenge

consider:
100-200mg IV/IM hydrocortisone
10mg IV/IM chloraphehamine

admit for observation (6hr)
consider prescription of self-injectable adrenaline pen

Question 13

additional managmet

Answer 13

carry x2 self injectable adrenaline
carry supply of antihistamines
counsel regarding allergy avoidance

food- dietician input
drugs- educate avoid, medic alert bracelets

venom- avoid bright clothing/fragrance/dustbins/

Question 14

desensitise

drugs to avoid

Answer 14

in cases where they have had a severe reaction

avoid ACEi switched to ca2+/ARBS
avoid beta-blockers
avoid NSAIDs
avoid MAOB/TCAs

Question 15

adrenaline autoinjectors

Answer 15

moderate-severe allergens
‘EpiPen’

mastocytosis= raised baseline mast cell tryptase levels. more inclined to have allergic reactions and potentially fatal ones.

Question 16

plymouth hospitals adrenaline-auto-injector

^ how to use adrenaline pens

Answer 16

watch that

Question 17

investigations for allergens

Answer 17

support diagnosis / if there is doubt regarding allergy

should never delay treatment

serum mast cell tryptase levels - 3 samples taken within 30 minute onset. 1-2 hours and 24 hours later. typically normalised by 4 hours. (at least 1 hr after the reaction started)

blood for specific IgE
SPT
challenge

Question 18

differentials for anaphylaxis

Answer 18

acute or chronic spontaneous urticaria/angiodema

• can be due to stress or infection
• differentiating factor is that anaphylaxis is much quicker where as these come on slower, over a few days and resolve slower

idiopathic anaphylaxis (difficult to find an obvious trigger)

non IgE mediated drug reaction
hereditary angiodema 
asthma exacerbation
carcinoid tumor
scombroid
mastocytosis

uptodate
nice guidelines/BSACI guidelines

Question 19

hereditary angiodema (HAE)

Answer 19

autosomal dominant inheritance

usually at least 1 family member affected