Congestion and Oedema Flashcards
What are congestion and oedema?
The relative excess of blood in vessels.
A passive, secondary process.
The accumulation of abnormal amounts of fluid in the extravascular compartment (ECF and body cavities).
What is DVT?
Local acute congestion.
Blood backs up in the veins, venules and capillaries - outflow is reduced, the pressure gradient is reduced, flow is reduced.
O2 is low - ischaemia and infarction occur.
What is hepatic cirrhosis?
Local chronic congestion.
Serious liver damage causes nodules of hepatocytes with fibrosis, causing a loss of normal structure.
How can hepatic cirrhosis increase the risk of haemorrhage?
Altered hepatic blood flow.
Portal blood flow blocked.
Congestion in portal vein and branches.
Increased portal venous pressure.
Several sites anastomose with systemic circulation (collateral).
What is congestive cardiac failure?
Generalised acute congestion.
Ischaemia or valve disease prevents the heart from clearing blood properly.
CO falls, eGFR falls, RAAS is activated.
The amount of fluid in the body rises.
Fluid overloads the veins.
Treatment - diuretics.
What are the signs for congestive heart failure?
Pulmonary - pulmonary oedema, left heart failure, crackles, tachycardia.
Renal - right heart failure, raised JVP, hepatomegaly, peripheral oedema.
What is the histology of hepatic central venous congestion?
Red pericentral hepatocytes - poorly oxygenated.
Pale periportal hepatocytes - better oxygenated (closer to hepatic arterioles).
‘Nutmeg’ liver - red and brown, pale and spotty.
What are the different types of oedema?
Peripheral oedema - increased ISF.
Effusions - fluid collections in body cavities.
Ascites - abdominal effusion.
Transudates - altered forces that act across the capillary wall.
Exudates - part of the inflammatory process, due to increased permeability.
How can LVF cause pulmonary oedema?
Left atrial pressure rises, so flow to pulmonary veins, capillaries, and arteries increases.
Pulmonary vascular pressure and BV increase, causing more filtration.
Transudate in the lungs causes oedematous widening of alveolar septa.
How can right HF cause pulmonary oedema?
The RV cannot empty in systole.
Blood is retained in systemic veins, increasing capillary pressure and filtration.
Secondary portal venous congestion occurs.
How can congestive cardiac failure cause pulmonary oedema?
Both the ventricles fail.
Pulmonary and peripheral oedema occurs at the same time (depends on HSP).
How can lymphatic blockage cause lymphoedema?
HSP is affected.
For example - fibrosis can decrease outflow.
What are the effects of abnormal renal function?
Salt and water are retained.
Intravascular fluid volume increases.
Secondary in HF - reduced renal flow.
Primary - acute tubular damage.
What can cause transudates?
Hypoalbuminaemia - oncotic pressure falls and filtration rises.
Nephrotic syndrome - leaky renal glomerular BM means protein is lost, and general oedema occurs.
Hepatic cirrhosis - fibrosis in the liver causes limited protein synthesis.
Malnutrition - insufficient protein intake.
What can cause exudates?
Damage to the endothelial lining - proteins and larger molecules leak out of cells (high protein).
Pneumonia (inflammation).
Burns.
