HAEMODYNAMIC DISORDERS Flashcards
what is haemodynamics?
the movement of blood
how is fluid balance maintained?
hydrostatic pressure pushing fluid into tissues and colloid osmotic pressure (protein concentration) returning blood to the vessels
what is oedema?
observable swelling caused by an increased fluid in interstitial tissue apce
what can cause oedema?
increases in vascular volume, descreases in plasma protein concentrations, changes in endothelial cell walls, lymphatic obstructions, sodium retenstion and inflammation
how does sodium retention cause oedema?
excess sodium causes increased hydrostatic pressure so more fluid escspes into tissues
how does inflammation cause oedema?
blood vessel permeability increases leading to the migration of fluids, proteins and leukoctes from the blood into the tissues
what is hyperaemia?
increased blood flow into a particular tissue
what is congestion?
descreased blood flow/venous return out of a tissue
what is reactive hyperaemia?
local vasodilation in response to oxygen debt and accumulation of metabolic waste
what is active hyperaemia?
increased blood flow in response to an period of activeness e.g. during exercise
whats an example of reactive hyperaemia?
raynaud syndrome
what can cause congestion?
physical obstruction of veins or failure of the heart to pump the blood away from the affected area
what is local congestion?
compression of blood vessels, impairing venous return
what is systemic congestion?
heart failure leading to impaired venous return
what is the haemostatic strategy?
how the body prevents bleeding and stops bleeding whilst keeping blood within the damaged vessels
what is a haemorrhage?
extravasation of blood due to vessel rupture
how much blood can cause hypovolemic shock?
> 15% of blood lost
what is hypovolemic shock?
an emergency condition in which severe blood or other fluid loss makes the heart unable to pump enough blood to the body
what are petechia?
minute haemorrhages being 1-2mm diameter
what are purpura?
small haemorrhages of 3-10mm diameter
what are ecchymosis?
subcutaneous haematoma greater than 1cm diameter
tends to have colour changes due to metabolism of haemoglobin to bilirubin and hemosiderin
aka a bruise
what is thrombosis?
the process of clotting and the formation of a blood clot within the vessel which remains attached to the vessel wall
what are the 2 arterial thrombi?
mural thrombi and occlusive thrombi
what are mural thrombi?
a thrombus which doesnt occlude the vessel so has minor clinical events
whats occlusive thrombi?
a thrombus that blocks the vessel so metabolic waste accumulates and downstream tissues dont receive blood flow = major clinical events
where do venous thrombi tend to happen?
around valves
what is an embolism?
a thrombus that becomes detached and moves within the blood vessel. it can lodge in small vessels causing occlusion and infarction
why do patients wear compression socks?
to prevent pulmonary embolisms- when a blood clot forms in a deep vein of the leg and it moves to block an artery in the lung
what is atherosclerosis?
a chronic inflammatory disease caused by the formation of fibro-fatty lesions in the walls of medium- large arteries
outline atherogenesis?
endothelial lesion
lipoproteins can now enter the lumen and are ingested by macrophages, forming foam cells
inflammatory cells are attracted
smooth muscle cells migrate to the surface of the plaque to create a fibrous cap
what is stenosis?
abnormal narrowing
what are the clinical implications for atherosclerosis?
coronary artery disease carotid artery disease peripheral artery disease chronic kidney disease aneurysms
what is ischaemia?
inadequate blood supply to any organ or tissue leading to an insufficient supply of oxygen and nutrients and inadequate removal of metabolic waste
what is hypoxia?
when a region is deprived of adequate oxygen supply at the tissue level
what are infarcts?
areas of ischemic necrosis caused by occlusion of blood vessels
what are examples of infarcts?
myocardial infarction, ischemic stroke and gangrene
what is an aneurysm?
an enlargement of a blood vessel caused by a weakness in the vessel wall
what are the complications of aneurysms?
rupturing, thrombosis and embolism
what are fusiform aneurysms?
those that bulge out on all sides of the blood vessel
what are saccular aneurysms?
those that only bulge to one side
what are false aneurysms also called?
pseudoaneurysms
what are false aneurysms?
abnormal outpouchings or dilatation of arteries which are bounded only by the tunica adventitia (the outermost layer of the arterial wall)
what are true aneurysms?
abnormal outpouchings or dilations of arteries that are bound by all 3 layers of the vessel wall
what is circulatory shock?
a clinical state characterised by systemic hypoperfusion leading to reduced delivery of oxygen and nutrients. this causes cellular injury and inadequate tissue function
what happens if circulatory shock is left untreated?
it can lead to multi-organ dysfunction syndrome
what is hypoperfusion?
the inadequate delivery of vital oxygen and nutrients to body tissues
what is cardiogenic shock?
the failure of the heart to pump sufficient blood
what is hypovolemic shock?
a loss of blood or plasma
what is obstructive shock?
an obstructuion to blood flow in the heart or a main pulmonary artery
what is neurogenic shock?
severe damage to the CNS which causes a loss of systemic stimulation of blood vessels. this leads to wide spread vasodilation causing the pooling of blood in extremeties and hypotension
what is sepsis?
a potentially life-threatening condition that occurs when the body’s response to an infection damages its own tissues so the organs function poorly and abnormally.
what is septic shock?
when sepsis causes a dramatic drop in blood pressure that can lead to severe organ problems and death.
what is anaphylactic shock?
Severe allergic reaction causes release of inflammatory mediators and cytokines which triggers a widespread vasodilation and hypoperfusion
what forms the plaque in atheroslcerosis?
the fatty streak with the fibrous cap
how can atherosclerosis lead to aneurysms?
it weakens vessel walls so they are more likely to bulge
describe the steps to infarction?
hypoperfusion -> Ischaemia -> infarction
what is Virchow’s triad?
the 3 factors that control thrombus formation
- venous stasis
- activation of blood coagulation
- vein damage
when does healing and repair of a wound happen in relation to inflammation?
same time
when should adequate tissue repair occur by?
3 weeks
what is resolution
the process of replacing damaged tissue with functioning, pristine tissue
why do some wounds leave scars>
if ideal healing doesn’t take place then the tissue is organised with ingrowth of granulation tissue
what is healing by primary intention?
when the wound is sharp and clean. we get a complete return to function with minimal scarring and loss of skin appendages
what is healing by secondary intention?
when a wound cant be stitched together which causes a large amount of tissue loss. this relied on the body’s own healing mechanisms which takes longer, has increased wound size, increased risk of infection and contamination.
what is exudate?
the fluid that leaks out of blood vessels into nearby tissues
what is transudate?
ultrafiltrate of plasma that contains, if any, few cells and no plasma proteins
what is the predominant cell type in acute inflammation?
neutrophils
what is the predominant cell type in chronic inflammation?
lymphocytes, macrophages and plasma cells
