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week 35 (Investigations (Tryptase (1-2hrs after), Histamine: from mast…
week 35
Investigations
Tryptase (1-2hrs after)
Histamine: from mast cells
IgE- serum in-vitro challenge
skin prick test
Allergy challenge test
unconsciousness
what could kill my patient immediately ?
Cardiac arrest, airway obstruction, breathing (oxygenation)
what could kill them in the next couple of minutes ?
overdose, intracranial hypertension or herniation, hypoglycaemia.
What could kill them in the next 10 minutes?
hypotension, anphylaxis, hyperkalaemia, MI, aortic disasters, and the ABCs
What could kill my patient over the next few hours?
Sepsis, intracranial haemorrhage, alcohol withdrawal, status epilepticus, necrotising fasciitis, abdominal catastrophies, metabolic problems (adrenal crisis, DKA, HONCK, thyroid disorders, hyponatraemia)
Resusitation of anaphylaxis
airway- 100% O2- 6-8L/min
breathing- nebulised salbutamol 5mg or nebulised adrenaline
circulation
ECG, O2 sats, pulse, BP, HR
fluid resus: 20ml/kg, saline fast push infusion.
adrenaline 300-500mcg IM (25-50mcg IV) every 2 min
delayed response
Corticosteroids: high dose hydrocortisone 200mg IV (takes 4-6hrs)
Antihistamines for urticaria: diphenhydramine H1 and ranitidine H2
Anaphylaxis
clinical features
wheeze/ stridor: bronchoconstriction
mottled skin: angiodema: upper airway obstruction
urticaria: histamine release
hypotension: vasodilation, extravasation of fluids, leads to CV collapse
tachycardia: cardiac compensation for hypootension.
vomiting and diarrhoea from local GIT response.
Definition: systemic allergy involving respiratory system, cardiovascular system and GIT if consumed.
Pathophysiology
Type 1 hypersensitivity response in genetically susceptible individuals
APC + antigen- B cell T cell + Bcell stimulation with cytokines from T-h2 cells (IL-4 and 5)
IgE
immunoglobulins formed with high affinity for basophils and mast cells
binds to Fc epsilon receptors on mast cells and when exposed to antigen, cross links IgE and upregulated cyclic AMP and causes degranulation of mast cell
Histamine
=vasodilation, bronchoconstruction, vessel permeability.
trypases
: proteases increase fluid extravasation
delayed response:
due to ecoisanoids, LT, PGs cause bronchoconstriction and inflammation
Differential diagnosis
Asthma, MI, C3 convertase deficiency, mastocytosis
post attack care
Epi-pen, referral to allergy specialist for skin test and challenge test and desensitisation planning, care plan and bracelet.