The Pathophysiology of Congestion and Oedema

Question 1

Darcy’s Law

Answer 1

Flow = Pressure gradient/Resistance

Question 2

Congestion

Answer 2

Relative excess of blood in vessels of tissue or organ, which is a passive process

Question 3

Examples of congestion

Answer 3

• Local acute congestion-
• Local chronic congestion
• Generalised acute congestion

Question 4

Local acute congestion

Answer 4

Deep vein thrombosis

Question 5

Local chronic congestion

Answer 5

Hepatic cirrhosis

Question 6

Generalised acute congestion

Answer 6

Congestive heart failure

Question 7

Consequences of DVT (6)

Answer 7

Local acute congestion
Decrease pressure gradient
Decreased outflow
Decreased flow
No O2- Ischaemia and infarction
Blood backed up in veins, venules and and capillaries

Question 8

Consequences of Hepatic Cirrhosis

Answer 8

Intervening fibrosis
Loss of normal architecture
Portal blood flow blocked
Increased portal venous pressure
Collateral circulation
Anastomosis with systemic circulation

Question 9

Where do DVTs normally originate and what can cause them (4)

Answer 9

Pelvis

Pelvic malignancy, pregnancy (bilateral), Abscess

Question 10

What is the appearance of the liver during local chronic congestion and what causes it

Answer 10

Fatty
Low levels of O2
Hepatic cells change to fatty cells as they have the least metabolic requirement and eventually die off

Question 11

Consequences of hepatic cirrhosis (local chronic congestion)

Answer 11

Oesophageal varices

Caput medusae

Question 12

What causes congestive heart failure

Answer 12

Heart is unable to clear blood from left and right ventricles due to ischaemia or valve problems

Question 13

Consequences of congestive heart failure

Answer 13

Decreased CO
Decreased GFR
Activation of renin-angiotensin-aldosterone system
water retention in body

Question 14

Left heart failure

Answer 14

Pulmonary oedema in lungs

Blood damns back into lungs

Question 15

Clinical presentation of left heart failue

Answer 15

Crepitations and Tachycardia

Question 16

Right heart failure

Answer 16

Central venous congestion in liver

Blood damns back into systemic circulation

Question 17

When blood damns back into systemic circulation what does that result in

Answer 17

Increased JVP pressure
hepatomegaly
Peripheral Oedema

Question 18

What causes oedema in the pulmonary circulation and peripheral circulation

Answer 18

Because the heart is too weak to pump the blood it accumulates and the pressure caused by the backflow causes fluid it seep out leading to oedema

Question 19

Which hepatocyte receives the best oxygen supply and why? Periportal or pericentral;

Answer 19

Periportal

Close proximation with hepatic arterioles and receives the most oxygenated blood

Question 20

Arterial side balance of pressure

Answer 20

Capillary hydrostatic pressure is greater than = filtration

Question 21

Venous side balance of pressure

Answer 21

Capillary oncotic pressure is greater than hydrostatic pressure = reabsorption

Question 22

Three components that affect net flux and filtration

Answer 22

1. Hydrostatic pressure
2. Oncotic pressure
3. Permeability characteristics and area of endothelium

Question 23

What does disturbance of starling forces lead to

Answer 23

Oedema

Question 24

Starling’s Hypothesis

Answer 24

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

Question 25

4 Starling Forces

Answer 25

hydrostatic pressure in the capillary (Pc) hydrostatic pressure in the interstitium (Pi) oncotic pressure in the capillary (pc ) oncotic pressure in the interstitium (pi )

Question 26

What is oedema

Answer 26

Accumulation of abnormal amounts of fluid in the extravascular compartment

Question 27

Transudate is caused by

Answer 27

alterations in the haemodynamic forced and is a sign of cardiac failure or hypoproteinemia

Question 28

Exudate is caused by

Answer 28

``` the inflammatory process due to an increase in vascular permeability Tumour Allergy Inflammation High protein/albumin in cells ```

Question 29

What are the events that occur in left ventricular failure (4)

Answer 29

 Increase in left arterial pressure- back flow to pulmonary veins, capillaries and arteries  Increase in pulmonary vascular pressure  Increase in pulmonary blood volume  Increase in hydrostatic pressure leads to increase filtration and pulmonary oedema

Question 30

What occurs in the lungs during left ventricular failure (3)

Answer 30

 Perivascular and interstitial transudate  Progressive oedematous widening of alveolar septa  Accumulation of oedema fluid in alveolar spaces

Question 31

Pathophysiology of peripheral oedema

Answer 31

Right heart failure Retained blood and back flow in systemic veins Increase in pressure- transudate

Question 32

Blockage of the lymphatic drainage leads to

Answer 32

Lymphoedema

Question 33

Primary cause for abnormal renal function

Answer 33

Acute tubular damage

Question 34

Secondary cause for abnormal renal fucntion

Answer 34

Heart failure reduced GFR

Question 35

Consequences of abnormal renal function (3)

Answer 35

Increased salt and water retention Increased intravascular fluid volume Oedema

Question 36

Causes of low protein oedema (3)

Answer 36

Hypoalbuminemia: 1. Nephrotic syndrome 2. hepatic cirrhosis 3. Malnutrition

Question 37

What can cause permeability oedema

Answer 37

Burns | Acute inflammation such as pneumonia

Question 38

What are the consequences of permeability oedema

Answer 38

Damage to endothelial lining leads to pores in the membrane which allow proteins and larger molecules to leak out reducing the oncotic pressure