Allergy And Anaphylaxis Flashcards
What is allergy?
An immune response to a normally harmless substance
What is a “ true allergy” and give some examples?
- these are the type 1 hypersensitivities that are IgE mediated
- eg asthma, hayfever, anaphylaxis, eczema
Give 3 examples of severe ADRS that may appear like severe allergies but are not IgE mediated ?
- SJS 🔥
- Toxic Epidermal Necrolysis
- Vancomycin red man syndrome caused by fast administration of the infusion
Describe the mechanism of a true allergy? (may need to explain this to a px in regards to explaining allergy and anaphylaxis and use why we use EpiPen)
-
Exposure/ sensitisation
- the allergen is exposed to plasma b cells which produce IgE antibodies in response to the antigens
- the IgE antibodies bind to IgE receptors on basophils and mast cells - Re - exposure
- the antigen bind to IgE antibodies on the basophils and mast cells when re exposed to the body again - thus results in degranulation of the mast cells and basophils and thus the subsequent release of histamine!
What are the effects of histamine on the body?
- 😩 urticaria rash and itch
- 🫁 smooth muscle contraction- hence we see bronchoconstriction and SOB and chest tightness in anaphylaxis
- 🛌 vasodilation - hypotension and angiodema
- 💦 increased leakiness of the capillary walls resulting in oedema and angiodema
- 🩸 circulatory collapse - anaphylaxis
What are some general symptoms of allergic reactions?
- 🤧 sneezing
- 😷 wheezing + cough
- 🤮 vomiting and diarrhoea 💩
- 🫁 SOB
- 💧 oedema, angiodema
- 😩 sinus pain
- 👃 runny nose
- 👀 👂 👄 itchy eyes , lips, ears and throat
- 🤢 sickness
How do we treat mild allergy?
(Ie swelling , hives)
- antihistamines
- steroid tablets
- Steroid creams
What are 3 drugs with side effects that patients often mistake or label as allergy?
- penicillin
-macrolides (ie erythromycin, clarithromycin) - opiates
What are some common side effects of penicillin?
- 🤮 nausea
- 💩 diarrhoea
- 🪰 thrush
What are the complications of being labelled PenA, or allergic to some antimicrobial when it’s not a true allergy?
- limits the choice in Abx we can administer
- Penicillin is one of the narrow spectrum Abx that is used for various gram +ve infections thus being labelled PenA put u at risk for AMR and reduced choice
What are some typical side effects of macrolides that px mistake as allergy?
- 🤮 nausea
- 💩 diarrhoea
- 😩 abdominal pain
What are some side effects of opiates that PX often mistake or label as allergy?
- 😴 sedation
- 😩 rash
- 🌠 hallucinations
What is anaphylaxis?
A severe allergic reaction where the body’s immune system becomes over reactive / hyper reactive when exposed to an allergen VERY QUICKLY!!!
⏰ it usually occurs within minutes of exposure to the allergen
It can be life threatening or FATAL
- ⚠️ anaphylaxis is a medical emergency
What are the symptoms that we need to look out for in regards to identifying anaphylaxis
We need to be aware of any problems with the patients airways, breathing, circulatation.
AND skin and mucosal changes - ie angiodema, urticaria and flushing
How might a patients airways be impacted in anaphylaxis?
- hoarse voice 🐴
- stridor
- swelling of the tongue 👅 and or throat
How might a patients breathing be impacted in anaphylaxis?
- wheeze
- cough
- cyanosis and respiratory depression
- increased respiratory rate
How might a patients circulation be impacted in anaphylaxis?
- hypotension
- px may feel dizziness, LOC
- px may present as pale and clammy
- Px may have arrhythmia or MI
What are the general symptoms of anaphylaxis (ie rationale for a px to administer their EpiPen)?
- chest tightness
- difficulty breathing
- feeling faint or dizzy
- swelling of tongue, throat, face affected areas
- syncope
Impending feeling of DOOOOOMMMMM
What do we administer in anaphylaxis>
- adrenaline
Why do we administer adrenaline in anaphylaxis, what are the effects on the body?
- vasoconstriction - thus aims to increase BP and HR
- reduces leakiness of capillaries - thus reduces oedema and swelling
- smooth muscle relaxation - opens up the airways
Where should a px administer their adrenaline autoinjectors?
- anterolateral aspect of the middle thigh
Do hives indicate allergy, and more specifically, anaphylaxis?
NO - urticaria can even present in times of stress
When paired with other symptoms of allergy advice px to take antihistamines, if it doesnt calm down or px gets anaphylactic symptoms - ADRENALINE AUTOINJECTORS!!
