Pathophysiology of congestion and oedema Flashcards
(31 cards)
What is congestion?
relative excess of blood in vessels of tissue or organ
Give characteristics of congestion?
passive process
acute or chronic
Describe deep vein thrombosis of the leg?
because vein is blocked
blood backs up in veins
blocks the venules and capillaries downstream
outflow of blood through proximal vessel is blocked and cause local acute congestion
pressure gradient across limb is reduced
resistance remains same
flow goes down as flow is proportionate to difference in pressure (blood flow= difference in pressure/ resistance)
no blood flow means no oxygen and therefore ischemia and infarction development
What does hepatic cirrhosis result from?
serious liver damage e.g. HBV, alcohol
What happens in hepatic cirrhosis?
liver gets damaged and get regeneration of the liver and this forms nodules of liver cells, hepatocytes and intervening fibrosis.
Loss of normal architecture- alteration in hepatic blood flow
Blockage of portal blood flow
-congestion in portal vein (Vein from digestive organs to liver) and branches
-increased portal venous pressure
- then get collateral circulation-several sites of portal vein anastomose with systemic circulation
Result of this is that there is local chronic congestion in the gut and veins- find very small vessels with small thin walls dilated and increasing pressure - haemorrhagic risk
What is congestive cardiac failure?
heart is dysfunctional and cant clear blood from right and left ventricles. Ineffective pump
Where do you see congestive heart failure?
ischaemia and valve disease
What is the pathophysiology of congestive cardiac failure?
cardiac output is reduced
and reduced flow through glomeruli -> activates RAAS and effect of that is it increases sodium and water retention in the body
too much fluid in vessels
and get too much blood flowing to heart- which can’t be pumped out
What are the effects of cardiac failure?
heart cannot clear blood from ventricles
blood dammed back in veins
lungs- pulmonary oedema
-left heart failure- blood dams back into lungs
-clinically crepitations in lungs, tachycardia
right heart failure- blood dams back to systemic circulation
- liver is first thing affected
-raised JVP
- feel hepatomegaly
-see peripheral oedema
What does congested liver look like?
red brown and pale spots
red areas- further from oxygen rich blood
pale areas- closer to oxygenated blood
Describe normal microcirculation?
capillaries- interstitium- capillaries and lymphatics
constant movement of fluid through capillary bed; process of dynamic equilibrium
driven by hydrostatic pressure from heart
balanced by osmotic pressures and endothelial permeability
filtration from capillary beds to interstitium
What are the three components that affect net flux and filtration?
hydrostatic pressure
oncotic pressure
permeability characteristics and area of endothelium
What is oedema?
accumulation of abnormal amounts of fluid in the extravascular compartment
- intercellular tissue compartment
-body cavities
When is it called peripheral oedema?
tissues
When is it called effusions?
body cavities
What is ascites?
Peritoneal fluid effusion
Give characteristics of oedema as a transudate?
-transudate
-result of alterations in the haemodynamic forces which across the capillary wall
-not much protein/ albumin
-lots of water and electrolytes
Give characteristics of oedema as an exudate?
part of inflammatory process and due to increased vascular permeability
tumour, inflammation, allergy
higher protein/ albumin content
water and electrolytes
high specific gravity
Describe pathophysiology of pulmonary oedema?
hydrostatic pressure-transudate
in left ventricular failure: ventricle can’t get rid and and there’s damming back into left atrium
increased left atrium pressure and means will pass back through pulmonary veins and to pulmonary artery
increased pulmonary vascular pressure
increased pulmonary blood volume
increase in pressure in pulmonary capillaries - then pushed into p interstitium
Describe what happens to pulmonary oedema in the lungs?
perivascular and interstitial transudate
progressively alveolar septa widen and spill over into alevolar spaces
Pathophysiology of peripheral oedema?
failure of RV and so have blood backing up into RA
backs up into systemic veins - increased pressure in capillaries-increased filtration and peripheral oedema
(also see secondary portal venous congestion via liver)
Describe congestive cardiac failure?
right and left ventricles both fail
pulmonary and peripheral oedema at same time
Describe pathophysiology of lymphatic blockage?
lymphatic obstruction-
hydrostatic pressure upset
as lymphatics are responsible for draining fluid out of the intestitium and back into venous circulation
if lymphatics blocked- lymphoedema
Why is upper limb oedema observed in giving radiotherapy to axilla?
breast cancer in axilla( contains a lot of lymphatic channels).
Radiation produces fibrosis and reducing outflow
