Pathophysiology of congestion and oedema Flashcards
What is Darcy’s law?
Q = blood flow P = pressure R = resistance
Q = total P / R
What law states flow is determined by total pressure divided by resistance?
Darcys law
What is congestion?
Excess of blood in vessels or tissue, passive process secondary to something else
Name an example of local acute congestion
Deep vein thrombosis
Name an example of local chronic congestion
Hepatic cirrhosis
Name an example of generalised acute congestion
Congestive heart failure
What causes hepatic cirrhosis?
Hep B
Alcohol
How does hepatic cirrhosis lead to congestion?
Damage causes fibrosis, leading to a loss of normal architecture and can block portal blood flow
What are two possible consequences of hepatic cirrhosis and blockage of portal blood flow?
Oesophageal varices Caput medusa (palm tree sign) - engorged superficial epigastric vein from umbilicus that can shunt to the femoral arteries
Define congestive heart failure
heart is unable to clear blood from right and left ventricles, ineffective pumping due to ischaemia or valve disease, so it cant meet the bodies needs
What are some signs and symptoms of CHF?
SOB, worse when lying down Fatigue Leg swelling (oedema)
What can cause CHF?
Valve disease IE MI Hypertension AF Excessive alcohol consumption Cardiomyopathy
How does CHF cause oedema etc?
Decreased CO leads to decreased GFR. This activates the RAAS system, leading to Na and H20 retention, causing oedema and increasing blood pressure.
How do you treat CHF?
Diuretics
What are some clinical signs of CHF?
Pulmonary oedema Left heart failure Tachycardia Right heart failure Increased JVP Hepatomegaly Peripheral oedema
What can be seen histologically in CHF?
Nutmeg liver - red/brown and pale spotty appearance macroscopically
What is Starlings hypothesis?
Starling’s hypothesis states that the fluid movement due to filtration across the wall of a capillary is dependent on the balance between the hydrostatic pressure gradient and the oncotic pressure gradient across the capillary.
What are the 4 starlings forces?
Capillary oncotic pressure
Capillary hydrostatic pressure
Interstitial oncotic pressure
Interstitial hydrostatic pressure
What three components affect net fluid flux and filtration?
Hydrostatic pressure
Oncotic pressure
Permeability and area of endothelium
What is ascites?
Abnormal fluid accumulation in the peritoneal/abdominal cavity
What are effusions?
Fluid collections in body cavities
What is the difference between transudates and exudates?
Transudates - alterations in haemodynamic forces
Exudates - changes in vascular permeability
Which has higher protein content: transudates or exudates?
Exudates
What causes transudates?
Cardiac failure
Fluid overload
What causes exudates?
Inflammation
Tumours
Allergy
Burns
What causes pulmonary oedema?
Transudates
What type of oedema is linked to left sided failure?
Pulmonary oedema
What type of oedema is linked to right sided failure?
Peripheral oedema
What is the result of lymphatic blockage?
Lymphoedema
What can cause hypoalbuminaemia and decreased protein levels?
Nephrotic syndrome
Hepatic cirrhosis
Malnutrition
