Blood Material Interactions Flashcards
Blood compatibility definition
the property of a material or device that permits it to function in contact with blood without inducing adverse reactions
Thrombogenicity local and systemic effects
local - disturbed flow/stasis –> blood clots
systemic - thrombi may embolise
chronic device may lead to ss destruction or consumption of circulating blood elements (mechanical destruction of RBCs -> anaemia)
BMI assessment 4 possible observations
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BMI evaluation methods and their two possible meanings
measure platelet adhesion
measure mass of adherent thrombus
measure platelet granule release
Virchow triangle
factors contributing to blood coagulation
surface
flow
blood
Blood composition
plasma - 55%
formed elements - 45%
-leukocytes & platelets
-RBCs (mainly)
Animal blood relevance?
Different chemistry but still useful for BMIs
Flow regimes?
Arterial - high wall shear rate -> thrombus of platelets
venous - low shear rate -> thrombus of RBCs in fibrin mesh (YES to heparin treatment)
Surface relevance?
mediates protein layer then platelet attachment
In vitro testing
direct contact, flow chamber with different flow regimes
usually short duration because blood source, handling methods, use of anticoags
In vivo testing
AV or AA shunts in animals
relevance to humans questionable
BMI concerns in devices
large SA of dialyzers and oxygenators
depletion of circulatory blood cells and proteins
immune/inflammatory response through activation of complement proteins and WBCs
thrombus interfering with device function
LVAD parts and BMI measured parameters
mechanical pump, electronic controller, power supply flow assessment coagulation emboli platelet activation and deposition complement leukocyte activation fibrinolysis
