Pathophysiology of Congestion and Oedema Flashcards
The passive movement of water is
Down its pressure gradient
Darcy’s law
Blood flow = change in pressure/resistance (Q=Δ P/R)
Congestion
relative excess blood in vessel soft tissue or organ
Example of local acute congestions
Deep vein thrombosis
Example of local chronic congestion
Hepatic cirrhosis
Example of generalise acute congestion
Congestive cardiac failure
Deep vein thrombosis of leg
Vein blocked by thrombosis causing localised acute congestion
Pathophysiology of deep vein thrombosis
Blood backs up in veins, venules and capillaries - decreased outflow of blood - local acute congestion - decrease in pressure gradient - decrease flow across systems - no oxygen so ischaemia and infarction
Why does pressure gradient decrease in deep vein thrombosis
Due to venous pressure rising to match arterial pressure decreasing the difference in pressure between the 2
Hepatic cirrhosis results from
Serious liver damage (eg. alcohol damage)
Regeneration of liver results in
Formation of nodules of hepatocytes with intervening fibrosis - loss of normal architecture
Pathophysiology of hepatic cirrhosis
Loss of normal liver architecture - altered hepatic blood flow - portal blood flow blocked - congestion in portal vein and branches - increased portal venous pressure - collateral circulation
Collateral circulation
Several sites anastomosing with systemic circulation
Local chronic congestion has a risk of
High pressure haemorrhage
Consequence of hepatic cirrhosis
Portal-systemic shunts
Congestive cardiac failure arrises from
The heart being unable to clear blood - ineffective pump
Pathophysiology of congestive heart failure
Reduced cardiac output - reduced renal glomerular filtration rate (GFR) - activation of renin-angiotensin-aldosterone system - increase in sodium and water retention - increase amount of fluid in body - increase fluid in veins (overload)
Treatment of congestive heart failure
Diuretics
Effects of congestive cardia failure
Back pressure, blood dammed back in veins
Lungs: pulmonary oedema - left heart failure - blood dams back into lungs
Liver: central venous congestion - right heart failure - blood dams back to systemic circulation
Signs of central venous congestion
Elevated JVP
Hepatomegaly
Peripheral oedema