The Pathophysiology of Congestion and Oedema

Question 1

What is Darcy’s law?

Answer 1

Blood flow = Total pressure/ Resistance

Question 2

What is congestion?

Answer 2

Relative excess of blood in vessels of tissue or organ

Question 3

What type of process is congestion?

Answer 3

Passive process, secondary phenomenon

Question 4

Give an example of local acute congestion

Answer 4

Deep vein thrombosis

Question 5

Give an example of local chronic congestion

Answer 5

Hepatic cirrhosis

Question 6

Give an example of generalised acute congestion

Answer 6

Congestive cardiac failure

Question 7

What does congestion cause?

Answer 7

Ischaemia and infarction

Question 8

What is hepatic cirrhosis a result of?

Answer 8

Serious liver damage

Question 9

What is the long term effect of hepatic cirrhosis on the liver?

Answer 9

Regenerated liver forms nodes of hepatocytes with intervening fibrosis so changes hepatic blood flow and can cause blockage of portal blood flow. This causes local chronic congestion with a haemorrhage risk

Question 10

What is the final consequence of hepatic cirrhosis?

Answer 10

Portal-systemic shunts

Question 11

What is a portal-systemic shunt?

Answer 11

A bypass of the liver by the body’s circulatory system

Question 12

What is congestive cardiac failure?

Answer 12

When the heart is unable to clear blood from the right and left ventricles, it reduces CO, which reduces renal glomerular filtration rate which increases the amount of fluid in the body so there is fluid overload in the veins

Question 13

What is the treatment of congestive cardiac failure?

Answer 13

Diuretics

Question 14

What is the effect of congestive cardiac failure on the lungs?

Answer 14

Pulmonary oedema

Question 15

How does pulmonary oedema happen?

Answer 15

There is left heart failure so blood dams back into the lungs

Question 16

What is the effect of congestive cardiac failure on the liver?

Answer 16

Central venous congestion

Question 17

How does central venous congestion happen?

Answer 17

There is right heart failure so blood dams back to the systemic circulation. This increases the JVP which causes hepatomegaly and peripheral oedema

Question 18

What does the liver look like in central venous congestion?

Answer 18

“Nutmeg” liver has red/brown and pale spots

Question 19

What is the name of the red spots in the liver?

Answer 19

Pericentral hepatocytes

Question 20

What is the name of the pale spots in the liver?

Answer 20

Periportal hepatocytes

Question 21

Which hepatocyte is better oxygenated?

Answer 21

Periportal hepatocytes due to the proximity of hepatic arterioles

Question 22

Why does filtration occur at the arterial side of a capillary?

Answer 22

Because capillary hydrostatic pressure is greater than capillary oncotic pressure

Question 23

Why does reabsorption happen at the venous side of the capillary?

Answer 23

Because capillary oncotic pressure is greater than capillary hydrostatic pressure

Question 24

What are the three factors that affect net flux and filtration?

Answer 24

Hydrostatic pressure
Oncotic pressure
Permeability and area off endothelium

Question 25

What is oedema?

Answer 25

Accumulation of abnormal amounts of fluid in the interstitium

Question 26

What is effusion?

Answer 26

Accumulation of abnormal fluid in body cavities

Question 27

What is oedema a result of?

Answer 27

Alterations in the haemodynamic forces acting across the capillary wall

Question 28

What is effusion a result of?

Answer 28

Inflammatory processes

Question 29

What is transudate?

Answer 29

Extravascular fluid that is low in proteins, specific gravity and nucleated cell types

Question 30

What is exudate?

Answer 30

A fluid rich in proteins, albumin, H2O, electrolytes and cellular elements that has seeped out of blood vessels, usually in inflammation. Has a high specific gravity.

Question 31

What causes oedema formed of transudate?

Answer 31

Cardiac failure | Fluid overload

Question 32

What causes oedema formed of exudate?

Answer 32

Tumour Inflammation Allergy Part of inflammatory process due to increased vascular permeability

Question 33

What is the pathophysiology of pulmonary oedema formed of transudate?

Answer 33

Left ventricular failure causes: Increased LA pressure Increased pulmonary vascular pressure Increased pulmonary blood volume Increased capillary hydrostatic pressure Increased filtration Pulmonary oedema Perivascular and interstitial transudate in the lungs Progressive oedematous widening of alveolar septa Accumulation of fluid in the alveolar spaces

Question 34

What is the pathophysiology of peripheral oedema caused by right heart failure?

Answer 34

``` RV cannot be emptied in systole Blood retained in the systemic veins Increased pressure in capillaries Increased filtration Peripheral oedema Secondary portal venous congestion ```

Question 35

What is the pathophysiology of lymphatic blockage?

Answer 35

Lymphatic obstruction Hydrostatic pressure upset Lymphedema

Question 36

What does abnormal renal function result in?

Answer 36

Increased salt and water retention Increased intravascular fluid volume Increased capillary hydrostatic pressure Oedema

Question 37

What is abnormal renal function secondary to?

Answer 37

Heart failure reduces renal blood flow

Question 38

When is there primary abnormal renal function?

Answer 38

With acute tubular damage such as in hypertension

Question 39

Why do low protein levels cause oedema?

Answer 39

Because capillary oncotic pressure requires normal protein levels to be normal

Question 40

What type of oedema is caused by low protein levels?

Answer 40

Transudate oedema

Question 41

Give examples of what can cause low protein oedema

Answer 41

Nephrotic syndrome Hepatic cirrhosis Malnutrition

Question 42

How does nephrotic syndrome cause oedema?

Answer 42

Causes leaky renal glomerular basement membrane Lose proteins Generalised oedema

Question 43

Oedema caused by endothelial permeability is which type of oedema?

Answer 43

Exudate oedema

Question 44

What is the pathophysiology of permeability oedema?

Answer 44

Damage to endothelial lining Increased number of pores in the membrane Proteins and larger molecules can leak out

Question 45

What can cause permeability oedema?

Answer 45

Acute inflammation such as pneumonia | Burns