The pathophysiology of congestion and oedema Flashcards
Define congestion
Relative excess of blood in vessels to tissue or organ
Why is congestion not like acute inflammation
As active hyperaemia occurs in acute inflammation due to an active process however congestion is due to a secondary process
What is the 3 pathological examples
Local acute congestion
Local chronic congestion
generalised acute congestion
What is a clinical example of local acute congestion
Deep vein thrombosis
What is the pathway of deep vein thrombosis that leads to infarction
Their is a blockage in the vein due to thrombosis, this causes a a back up blood in the veins,
decreasing the outflow of blood = local congestion
Pressure gradient decreases, and therefore decreases flow across the system, which decreases the amount of oxygen in the tissue resulting in ischaemia and infarction
What is a clinical example of local chronic congestion
Hepatic cirrhosis
What is the cause of hepatic cirrhosis
Serious liver damage (due to alcohol, HBV etc)
local chronic congestion increases the risk of what
Haemorrhage
What is the consequence of hepatic cirrhosis
Portal systemic shunts-s a bypass of the liver by the body’s circulatory system
What is a clinical examples of generalised acute congestion
Congestive cardiac failure
What is congestive cardiac failure
heart unable to clear blood from the right and left ventricles
What is the aetiology of congestive heart failure
Ineffective pumps due to ischaemia or valvular disease
What is the pathophysiology of congestive heart failure
Ineffective pumps decrease the cardiac output,
decreasing the renal glomerular filtrate rate
which increases tubular retention of ionic water
This increases the amount of fluid in the body,
and causes a increase fluid overload in the veins that become congested
What is the treatment for congestive heart failure to reduce the fluid overload
Diuretics
How does damage to other organs occur in congestive heart failure
heart cannot clear the blood from ventricles, resulting in back pressure and blood draining back in the veins
What causes central venous congestion in the liver
Right heart failure
What are the clinical signs of right heart failure causing central venous congestion in the liver
increased JVP
Hepatomegaly
peripheral oedema
What causes pulmonary oedema (acute or chronic) in the lungs
Left heart failure
What is the clinical sings of left heart failure causing pulmonary oedema
Crepitations in the lungs breathlessness
tachycardia
What is the morphology of central venous congestion
Nutmeg” liver red/brown (pericentral); pale spotty (periportal) appearance macroscopically
What are the three components that affect net flux and filtration around the body
hydrostatic pressure from heart
Balanced by osmotic pressures
endothelial permeability
= starlings forces
Upsetting any of the starling forces can lead to what
Oedema
Define oedema
Accumulation of abnormal amounts of fluid in the extravascular compartment;
intercellular tissue compartment (extracellular fluid)
or
body cavities
Increased interstitial fluid results in what type of oedema
Peripheral oedema
Fluid collection in the body cavities results in what type of oedema
Effusion oedema
What is the two aetiologies of oedema
Trasudate oedema - alteration of the haemodynamic forces which act across the capillary wall
Exudate oedema - part of the inflammatory price due to an increase in vascular permeability
What is the causes of transudate oedema
Cardiac failure
Fluid overload
What is the cause of exudate oedema
Tumour
Inflammation
allergy
What is the differences between truncate and exudate
Exudate;
high protein and albumin content where transudate has a low content
Transudate has more H2O and electrolytes than exudate
Exudate is high specific gravity, where transudate has low specific gravity
(due to protein contents)
What is the different aetiologies of oedema
Congestive heart failure: LH- Pulmonary oedema
RH -Peripheral oedema
Lymphatic blockage
hypoalbuminaemia
abnormal renal function
inflammation
What is the aetiology of pulmonary oedema
Transudate - Left ventricular failure upsetting hydrostatic pressure
What is the pathophysiology of pulmonary oedema
Left ventricular failure, increase left atrial pressure, this back flows to increase pulmonary vascular pressure, increasing pulmonary blood volume and concentration
This increase the filtration and in the lungs water flows out into the alveolar septa - creating a accumulation f oedema fluid in alveolar spaces
What is the aetiology of peripheral oedema
transudate - due right heart failure
-unable to empty RV in systole
or
-secondary portal venous congestion via the liver
What is the pathophysiology of peripheral oedema
Heart unable to empty right ventricle in systole, therefore blood is retained in the systemic veins, increasing the pressure in the capillaries, which increase the filtration, resulting in the peripheral oedema
What can cause pulmonary oedema and peripheral oedema at the same time
Congestive heart failure - as right and left ventricles fail
What is the pathophysiology of lymphedema causing oedema
Lymphatic system is blocked, this results in fibrosis, decreasing the outflow, therefore accumulation of fluid results in oedema
What is the aetiology of reduced renal blood flow - decreased renal function
Primary to acute tubular damage e.g. hypotension
Secondary to Heart failure
What is the pathophysiology of decreased renal function and oedema
Abnormal renal function results in Salt (NaCl) and H2O retention
This increase intravascular fluid volume
causes oedema
What is the different clinical example of how hypoalbuminameia conditions that result oedema
- nephrotic syndrome leaky renal glomerular basement membrane; lose protein;
- hepatic cirrhosis diffuse nodules and fibrosis in liver; liver unable to synthesise enough protein
- malnutrition insufficient intake of protein
How does hypoalbuminaemia result in oedema
Oncotic pressure is dependant is normal protein levels, if protein levels decrease, oncotic pressure decrease, therefor increasing filtration resulting in oedema
What is the aetiology of permeability oedema
exudate - Acute inflamaation, eg pneumonia, burns etc
What is the pathophysiology of permeability oedema
Damage to the endothelia lining, causes an increase in pore size in the membrane, therefore proteins and larger molecules as well as H2O can leak out
resulting in oedema
