Haemodynamic Disorders Flashcards
define ‘extravasation’
where increased BP causes vessel walls to become leaky
What does hydrostatic pressure cause?
Fluid to be driven OUT of capillary into tissues
What is colloid osmotic pressure/oncotic pressure?
Pressure that pulls fluid back into vessels. linked with protein concentrations (e.g. albumin concs)
define ‘oedema’
abnormal increased fluid in interstitial tissue space
What would increased hydrostatic pressure cause and name a reason for it occuring.
It would cause oedema. Caused by heart failure or localised in limbs by something such as a DVT
What is anasarca?
Oedema caused by malnutrition - not enough protein content in plasma so causes oedema.
define haemorrhage
extravasation of blood (not just fluid) due to vessel rupture
What percentage of blood does someone need to lose to be classified as haveing hypovolemic shock
More than 20%
What is petechiae and what causes it?
minute haemorrhages (1-2mm) of skin and mucosa. caused by thrombocytopenia, clotting factor deficiency or increased pressure in capillaries
What is pupura and what causes it?
small haemorrhage (3-5mm) usually due to trauma or vasculitis
define ecchymosis/bruises
subcutaneous haematoma
Define thrombosis
formation of blood clot on vessel wall.
Define embolism
solid, liquid or gaseous mass carried in the blood to a site distant from the point of origin. Most of time clinically you see thromboembolisms
What do you call an arterial thrombi that does not occlude a vessel?
Mural thrombi
what do you call a thrombi that blocks a vessel?
Occlusive thrombi
Thrombi that form in arteries are driven by what?
Platelets
Thrombi that form in veins are driven by what?
Fibrin due to hypercoagulation from blood stasis
When will giving anti-platelet drugs not work for a thrombus?
When it’s in veins because the clot is due to stasis in veins, not due to coagulation
define hyperaemia
increased blood flow in tissue
What is the difference between reactive and active hyperaemia?
Reactive - vasodilation caused by oxygen debt or accumulation of metabolic waste.
Active - vasodilation in response to period of activation (e.g during exercise)
Name a possible cause of venous congestion
1) venous pressure increased
2) obstruction inside vein
3) obstruction outside vein (e.g. tumour)
Define Shock
organs not receiving enough o2 and nutrients to function properly
Define cardiogenic shock and name a cause
failure of heart to pump enough blood.
causes: myocardia damage
define hypovolemic shock
loss of blood or plasma (e.g. haemorrhage or severe burns)
What is neurogenic shock and what causes it?
sympathetic NS adrenergic stimulation causing wide spread vasodilation, pooling of blood in extremeties and hypotention.
caused by severe damage to CNS
What happens in anaphylactic shock?
Severe allergic reaction causes release of inflammatory mediators and cytokines which triggers widespread vasodilation and hypoperfusion.
define sepsis
uncontrolled systemic reaction to bacteraemia
