Congestion Flashcards
Define Congestion
A relative excess of blood in the vessels of a tissue or organ often leading to ischaemia and infarction
What are the types of congestion?
Acute/Chronic
Localised/Generalised
What is oedema?
An accumulation of abnormal amounts of fluid in the extravascular compartment.
What do we call an oedema into a body cavity?
An effusion
What do we call an abdominal cavity effusion?
Ascites
What causes oedema?
Upsetting any of the starling forces:
> Filtration coefficient - the vessels permeabilty to H2O
> Capillary/interstitial oncotic pressure
> Capillary/Interstitial hydrostatic pressure
> Reflection coefficient - permeability to protiens (lower is more permeable)
What are the 2 types of oedema?
Transudate (low Protein) oedema {low specific gravity}
Exudate (Permeability) oedema {high specific gravity}
What causes a transudate oedema?
Altered haemodynamic forces acting across the capillary walls.
Congestion -> Increases capillary hydrostatic pressure
Hypoalbuminaemia -> Decreases capillary oncotic pressure
What does specific gravity mean?
The conc. of water soluble molecules in a fluid.
Give some causes for hypoalbuminaemia?
Nephrotic Syndrome - Proteins lost through leaky glomerular BM
Hepatic Cirrhosis - Liver cant make normal amounts of protein
Malnutrition - low protein intake
What causes an exudate oedema?
Increase in size/number of ‘pores’ in the endothelial lining which decreases the osmotic reflection coefficient so more, larger molecules pass through.
This can be caused by endothelial damage (e.g. burns, inflammation), acute inflammation (allergy, wound) or tumour.
How does hepatic cirrhosis cause congestion?
The regenerating liver forms nodules of hepatocytes with intervening fibrosis which alters the normal architecture of the liver, thus affecting blood flow.
The altered hepatic blood flow and/or blockage of the portal blood flow from the gut causes congestion.
this can cause palpable hepatomegaly
What type of oedema is a pulmonary oedema?
Usually a transudate oedema due to increased hydrostatic pressure in the pulmonary circ.
What are the main causes of peripheral oedema?
Blood being retained in the veins systemically due to RHF
Or locally due to a DVT or Embolism.
What is a lymphoedema?
Where a lymphatic obstruction increases the local lymphatic hydrostatic pressure and fluid flows out the lymph into the interstitium
