Congestion and Oedema

Question 1

What is the key thing to remember in congestion and oedema?

Answer 1

Water flows downhill, down a pressure gradient.

Things must do down a pressure gradient otherwise it won’t flow.

Question 2

What is the critical relationship (ohm’s law)?

Answer 2

Q = deltaP/R
Q = BF, P = pressure, R = resistance.

Question 3

What is congestion?

Answer 3

Relative excess of blood in the vessels of tissue or organ.

Passive process, secondary phenomenon (not like active inflammation where it is active hyperaemia).

Question 4

Is congestion acute or chronic?

Answer 4

Can be either.

Can become acutely congested - e.g. when grabbed by the throat, or chronic - goes on for long time.

Question 5

What would a congested vein in the leg look like?

Answer 5

Red, almost purple coloured, full of blood, colour difference very noticeable and swollen.

(in this case due to DVT)

Question 6

Give the clinical categories of congestion and give examples that fall under these categories.

Answer 6

Local acute congestion, e.g. CVT
Local chronic congestion, e.g. hepatic cirrhosis
Generalise acute congestion, e.g. congestive cardiac failure.

Question 7

Describe how DVT leads to congestion –> ischaemia and infarction.

Answer 7

Vein blocked causing local acute congestion. Blood backs up in veins, venues, capillaries. Decreased outflow of blood –> local acute congestion –> decreased pressure gradient –> decreased flow across system (Ohm’s law). So no oxygen leading to ischaemia and infarction.

Question 8

What is hepatic cirrhosis?

Answer 8

Regenerative nodules of hepatocytes with intervening fibrosis. Results from liver damage, e.g. HBV, alcohol.

Question 9

What happens to the normal architecture of the liver in hepatic cirrhosis? And what is the effect of this?

Answer 9

Loss of normal architecture = altered hepatic BF.
Portal BF blocked - congestion in portal vein and branches, increased portal venous pressure. Collateral circulation - several sites anastomose with systemic circulation.
Local chronic congestion.

Question 10

What is the major risk with hepatic cirrhosis?

Answer 10

Haemorrhage risk.

Question 11

Describe the path of hepatic blood flow?

Answer 11

Blood flows from intestines to liver then to vena cava as liver wants to get proteins and detoxify things etc…

Question 12

What does hepatic cirrhosis look like histologically?

Answer 12

Hepatocytes in lumps, bro bands of tissue b/w. Loss of normal vascular pattern that upsets hepatic BF.

Question 13

What are oesophageal varices?

Answer 13

Result of portal hypertension, congestion causes back up of blood so enlarged thickened vessels. If puncture this absolute firing of blood out.

Question 14

What are caput medusae?

Answer 14

Distended and engorged superficial epigastric veins Symptom of portal hypertension (result of back up of blood from blockage in liver).

Question 15

What can cause congestive heart failure?

AKA biventricular failure

Answer 15

When the heart is unable to clear blood (right and left ventricles) - can be due to ineffective pump, e.g. ischaemia, valve disease.

Question 16

What is the pathophysiology of congestive cardiac failure?

Answer 16

Decreased CO, decreased renal glomerular filtrate rate –> activation of renin-angiotensin-aldosterone system –> increase in sodium and therefore water retention. So increases amount of fluid in the body. Leads to fluid overload in the veins.

Question 17

How do you treat this overload of fluid?

Answer 17

Diuretics.

Question 18

How is water pulled back into the kidney tubules?

Answer 18

Increased ionic retention and sodium pulled back in and water pulled back in with it.

Question 19

What are the effects of congestive cardiac failure?

Answer 19

Heart cannot clear blood from ventricles.
Back pressure, blood dammed back in veins.
Liver - central venous congestion - right heart failure dams back into the venous system. Acute and chronic changes in lung - pulmonary oedema.

Question 20

What signs and symptoms are you looking for in congestive cardiac failure?

Answer 20

Liver - central venous congestion: increased JVP, hepatomegaly, peripheral oedema.

Pulmonary oedema: crepitations in lungs, tachycardia (working hard to clear lot of fluid in chest).

Question 21

Describe the appearance of the liver in hepatic central venous congestion.

Answer 21

Nutmeg liver - red/brown and pale spotty appearance macroscopically.

Red = haemorrhaging, pale = poor function.

Question 22

How are the pericentral hepatocytes (red) affected in hepatic central venous congestion?

Answer 22

Stasis of poorly oxygenated blood.

Question 23

How are the periportal hepatocytes (pale) affected in hepatic central venous congestion?

Answer 23

Relatively better oxygenated due to proximity of hepatic arterioles.

Question 24

Describe the normal microcirculation.

Answer 24

Constant movement of fluid through capillary beds, process of dynamic equilibrium.
Filtration from capillary beds to interstitial.

Question 25

What forces are involved in normal circulation?

Answer 25

Driven by hydrostatic pressure from heart, balanced by osmotic pressures and endothelial permeability.
Involves lymphatics.

Question 26

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

Answer 26

Hydrostatic pressure
Oncotic pressure
Permeability characteristics and area of endothelium

Question 27

What does disturbance in the normal components of microcirculation cause?

Answer 27

Oedema.

Question 28

What is Starling’s Hypothesis?

Answer 28

Net filtration (Jv)= [(force favouring filtration/flow of fluid out of vessel) - endothelial permeability to proteins x (forces opposing filtration/keeping fluid in vessel)] x endothelial permeability to H2O x area of capillary bed

Question 29

Define oedema.

Answer 29

Accumulation of abnormal amounts of fluid in the extravascular space (intracellular tissue spaces (ECP) or body cavity.

Question 30

How do peripheral oedema and effusions differ?

Answer 30

Fluid collections in body cavity = effusions.

Peripheral oedema - increased intersistal fluid in tissues.

Question 31

Give examples of effusions.

Answer 31

Pleural, pericardial, joint effusions.

Abdominal cavity = ascites.

Question 32

Describe oedema as a transudate.

Answer 32

Alterations in the haemodynamic forces which act across the capillary wall. Cardiac failure, fluid overload.
Not much protein/albumin (few cells)
Lots of water and electrolytes.
Low specific gravity.

Question 33

Describe oedema as an exudate.

Answer 33

Part of inflammatory process due to increased vascular permeability. 
Tumour, inflammation, allergy. 
Higher protein/albumin content.
Water and electrolytes. 
High specific gravity.

Question 34

What happens in pulmonary oedema?

Answer 34

Too much fluid going to the lungs, leaks out into alveoli and decreases gas exchange.

Question 35

What is the pathophysiology of pulmonary oedema?

Answer 35

Hydrostatic pressure - transudate
LVF
- increased L atrial pressure –> passive retrograde flow to pulmonary veins, capillaries and arteries.
- increased pulmonary vascular pressure
- increased pulmonary blood volume
- increased pressure –> increase filtration and pulmonary oedema

Question 36

What are the effects of pulmonary oedema in the lungs?

Answer 36

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

Question 37

Describe the pathophysiology of peripheral oedema.

Answer 37

R heart failure - cannot empty RV in systole.
Blood retained in systemic veins –> increased P in capillaries, increased filtration –> oedema.
Also secondary portal venous congestion via liver.

Question 38

What happens in congestive cardiac failure to lead to pulmonary and peripheral oedema?

Answer 38

R and L ventricles fail at same time.

All about hydrostatic pressure.

Question 39

Describe the pathophysiology of lymphatic blockage.

Answer 39

Lymphatic obstruction – hydrostatic pressure upset.

Lymphatic drainage is required for normal flow. If blocked –> lymphedema.

Question 40

When is lymphedema most common?

Answer 40

Breast cancer may req radiotherapy to axilla, which can cause fibrosis and scarring of lymph vessels, leading to blockage, decreased flow and oedema of the upper limb.

Question 41

What happens during abnormal renal function?

Answer 41

Salt and H2O retention.

Question 42

What can do you get secondary to heart failure?

Answer 42

Reduced renal BF.

Question 43

What is the reason for primary oedema in abnormal renal function?

Answer 43

Acute tubular damage, e.g. hypotension.

Question 44

What is the pathophysiology of oedema in abnormal renal function?

Answer 44

Decreased renal function, leading to increased salt and water retention, increased intravascular fluid volume, secondary increased capillary pressure –> oedema.

Question 45

Describe the pathophysiology of low protein oedema.

Answer 45

Oncotic pressure - transudate.

Hypoabluminaemia –> decreased capillary oncotic pressure –> increased filtration.

Question 46

Give examples of conditions causing low protein oedema.

Answer 46

Nephrotic syndrome –> leaky renal glomerular basement membrane, lose protein, generalise oedema.

Hepatic cirrhosis –> diffuse nodules and fibrosis in liver, liver unable to synthesise enough protein

Malnutrition –> insufficient protein intake.

Question 47

What are examples of permeability oedema?

Answer 47

Acute inflammation e.g. penumonia and burns.

Question 48

What occurs in permeability oedema?

Answer 48

Damage to endothelial lining –> increased no of pores in membrane so proteins and larger molecules as well as water leaks out.