Pathophysiology of Congestion and Oedema Flashcards
What is congestion?
Relative excess of blood in vessels of a tissue or organ, a passive process
What is the first thing noticed in congestion?
Colour difference - red, almost purple in colour
Examples of local acute congestion
DVT
Example of local chronic congestion
Hepatic cirrhosis (liver fibrosis)
Example of generalised acute congestion
Congestive cardiac failure
When does congestive heart failure?
Occurs when the heart is unable to clear blood, from both the right and left ventricles due to an ineffective pump (e.g. valve disease, ischaemia)
Pathology of congestive heart failure
Decrease in CO
Decreased GFR activates RAAS system leads to increased Na and H20 retention
Increased amount of fluid in the body
Results in fluid overload in the veins - congestion.
What is the treatment for fluid overload in the body?
Diuretics
Effects of congestive heart failure
Heart cannot clear blood from ventricles
Back pressure in the system, blood dammed back into the veins
Liver gets central venous congestion, which leads to right heart failure and increased JIV, hepatomegaly and peripheral oedema
Acute and chronic changes in lungs - pulmonary oedema. Left heart failure and shows clinically by tachycardia and creps in the lungs
What does the liver look like in hepatic central venous congestion?
“Nutmeg Liver” - brown/red and pale spotty appearance
Red pericentral hepatocytes - stasis of poorly oxygenated blood
Periportal hepatocytes (pale) - relatively better oxygenated due to proximity of hepatic arterioles
Causes of vascular congestion
DVT of leg
Hepatic cirrhosis
What is a consequence of vascular congestion?
Systemic portal shunts
Pathology of DVT
Blocked vein
Blood backs up the veins, venules and capillaries
This decreases the outflow of blood
Local, acute congestion
Decreased pressure gradient across the capillary beds
Decreased flow across the system
No oxygen leads to ischaemia and infarction (venous infarction common in gut and rare in DVT)
Pathology of Hepatic cirrhosis as a chronic congestive process
Regenerative nodules of hepatocytes with intervening fibrosis
Results from liver damage
Loss of normal architecture leads to altered hepatic blood flow
The portal blood flow then gets blocked due to congestion in the portal vein and branches causing increased portal venous pressure. Also in the collateral circulation several sites anastomose with systemic circulation. This therefore disrupts function of the gut
Local chronic congestion and therefore haemorrhage risk
Examples of systemic portal shunts
Oesophageal varices
Caput medusae
What is a very serious risk with systemic portal shunts?
Haemorrhage