pathophysiology of congestion and oedema

Question 1

down what gradient does water (and all fluid in the body) flow?

Answer 1

pressure

Question 2

what does Darcy’s law state and what does it mean phyiologically?

Answer 2

Q= change in pressure/resisitance

any changes in pressure or resistance of the cardiovascular system will result in a change in blood flow

Question 3

what is congestion?

Answer 3

relative excess of blood in vessels of tissues or organ

Question 4

does congestion involve active hyperaemia?

Answer 4

no

Question 5

give an example of local acute congestion?

Answer 5

deep venous thrombosis

Question 6

give an example of local chronic congestion?

Answer 6

hepatic cirrhosis

Question 7

give an example of generalised acute congestion?

Answer 7

congestive cardiac failure

Question 8

describe the pathophysiology of DVT causing infarction and ischaemia?

Answer 8

1.bloood backs up in the veins, venules and capillaries
2. decreased outflow of blood
3, local, acute congestion
4. decrease in pressure gradient
5. decrease in flow as a result of this
6. no O2 supply so ischaemia and infarction

Question 9

what does hepatic cirrhosis result from?

Answer 9

serious liver damage from hepatitis B virus or alcohol

Question 10

what is the pathophysiology of hepatic cirrhosis?

Answer 10

1, serious liver damage

2. regenerating liver forms nodules of hepatocytes with intervening fibrosis
3. this alters hepatic blood flow
4. so causes congestion in portal vein and branches.
5. increased portal venous pressure
6. and there is an increase in collateral circulation

Question 11

what are some consequences of portal-system hypertension?

Answer 11

blood is shunted to areas causing features like oesophageal varices and caput medisae

Question 12

what is dangerous about oesophageal varices?

Answer 12

they only have a thin lining over them so can easily be ruptured, causing haemorrhage

Question 13

what is congestive cardiac failure?

Answer 13

the heart is unable to clear blood from the right and left ventricles (the heart is an ineffective pump)

Question 14

what is the pathophysiology of congestive cardiac disease?

Answer 14

1. decrease in cardiac output
2. decrease in renal glomerular filtration rate
3. this causes the activation of the renin-angiotensin-aldosterone system
4. this causes sodium and water retention
5. therefore there is an increase in the amount of fluid in the body
6. there is a fluid overload in the veins

Question 15

what is the pathophysiology of pulmonary oedema caused by left ventricular failure?

Answer 15

1. increase in left atrial pressure
2. passive retrograde flwo to pulmonary veins, capillaries and arteries
3. increase in vascular pressure
4. increase in pulmonary blood volume
5. increased hydrostatic pressure leads to increased filtration

Question 16

what are the signs of central venous congestion?

Answer 16

increased JVP, hepatomegaly, peripheral oedema

Question 17

what causes central venous congestion?

Answer 17

right heart failure-blood damns back to systemic circulation

Question 18

what is the appearance of hepatic central venous congestion?

Answer 18

nutmeg appearance, red/brown and pale spotty appearance macroscopically

Question 19

what is the route of fluid from the microcirculation?

Answer 19

capillaries-interstitium-capillaries and lymphatics

Question 20

what are three components that affect net flux and filtration? and disturbance of any of these causes what?

Answer 20

• hydrostatic pressure
• oncotic pressure
• permeability characteristics and area of endothelium

causes oedema

Question 21

what is oedema?

Answer 21

accumulation of abnormal amounts of fluid in the extravascular compartment

Question 22

what are effusions and give some examples?

Answer 22

fluid collections in body cavities.

pleural, pericardial and joint effusions, ascites

Question 23

what is transudate oedema caused by?

Answer 23

alterations in the haemodynamic forces which act across the capillary wall

Question 24

what can cause transudate oedema?

Answer 24

• heart failure, fluid overload
• hypoproteinaemia
• lots of water and electrolytes
• low specific gravity

Question 25

what are the causes of exudate oedema?

Answer 25

- inflammation - tumour - allergy - higher protein/albumin content of cells - high specific gravity

Question 26

what is the pathophysiology of pulmonary oedema caused in the lungs?

Answer 26

- perivascular and interstitial transudate - progressive oedematous widening of alveolar septa - accumulation of oedema fluid in alveolar spaces

Question 27

what is the pathophysiology of peripheral oedema from right heart failure?

Answer 27

1. right heart failure 2. blood retained in systemic veins 3. increase in pressure in capillaries 4. increase in filtration 5. peripheral oedema

Question 28

what kinds if oedema does congestive cardiac failure cause?

Answer 28

pulmonary oedema | peripheral oedema

Question 29

what is the kind of oedema caused lymphatic system blockage?

Answer 29

lymphoedema

Question 30

what are the common causes of lymphoedema?

Answer 30

- fibrosis from radiotherapy - compression of lymphatic vessels eg. by tumour - invasion of tumour into lymphatics

Question 31

what is the pathophysiology of oedema in abnormal renal function?

Answer 31

1. increased Na and water retention 2. increased intravasclular fluid volume 3. secondary increase in hydrostatic pressure 4. oedema

Question 32

give an example of a cause of primary abnormal renal function causing oedema?

Answer 32

hypertension causing acute tubular damage

Question 33

give an example of a cause of secondary abnormal renal function causing oedema?

Answer 33

heart failure causing reduces renal blood flow

Question 34

what is the pathophysiology of low protein oedema?

Answer 34

- decreased protein content of blood - decreased oncotic pressure - increased filtration

Question 35

what are three causes low protein oedema?

Answer 35

nephrotic syndrome -leaky glomerular so lose protein hepatic cirrhosis-liver can't synthesise enough protein malnutrition-insufficient intake of protein

Question 36

what is the pathophysiology of permeability oedema?

Answer 36

- damage to endothelial lining - increase in membrane pores - water leaks out - proteins and large molecules also leak out

Question 37

what are some causes of permeability oedema?

Answer 37

``` burns acute inflammation (eg. pneumonia) ```