Congestion and Oedema

Question 1

Define congestion

Answer 1

Increased content of blood in an organ or tissue.

Question 2

Define oedema

Answer 2

Excess of interstitial fluid(definition does not apply to the brain)
In the brain: Excess of fluid within the brain

Question 3

define Anasarca

Answer 3

Severe generalised oedema

Question 4

Define pericardial effusion

Answer 4

Accumulation of fluid in the peritoneal, pleural and pericardial cavities respectively.

Question 5

define pleural effusion

Answer 5

A condition where excess fluid accumulates in the space between the lungs and the chest wall, making breathing difficult and painful.

Question 6

Distinguish between exudate and Transudate

Answer 6

Exudate:
.Specific Gravity(SG)>1,020
.Contains inflammatory cells
.associated with increased vascular permiability
.a consequence of inflammation

Transudate
.Specific Gravity<1,020
.imbalances of forces equilibrating fluid

Question 7

Describe the possible pathogenesis of localized and generalized oedema

Answer 7

Localized
.Increased hydrostatic pressure of blood:
◦ venous thrombosis
◦ pressure on veins from outside (tourniquet, tumour)
◦ cirrhosis of liver with portal hypertension
 Increased vascular permeability:
◦ any cause for an acute inflammatory process
Abnormality of lymphatics:
◦ congenital abscence of lymphatics (Milroy’s disease)
◦ obstruction of lymphatics:
◦ carcinoma (peau d’orange in breast carcinoma)
◦ irradiation (fibrous scarring of lymphatics)
◦ surgical removal of lymphatics (block dissection of lymph nodes)
◦ by filarial worms (`elephantiasis’)

Generalised
.Increased hydrostatic pressure
◦ cardiac failure
.Increased vascular permeability:
◦ Systemic hypoxia / prolonged ischaemia
◦ Bacterial toxins
◦ Sepsis
◦ Generalised fluid movement to interstitium
Na+
and obligate water retention
◦ Salt and water retention can also be a primary cause of oedema.
Carcinogenesis 46
◦ Diminished renal perfusion and glomerular filtration – Salt retention occurs whenever renal
function is compromised, such as in primary disorders of the kidney and disorders that
decrease renal perfusion.
▪ Glomerulonephritis, nephrotic syndrome, renal failure.
▪ Cardiac failure
▪ Cushing’s syndrome (excess ACTH/ cortisone produced or administered)
◦ Activation of the renin-angiotensin-aldosterone axis
◦ Increased salt retention, with obligate associated water, causes both increased hydrostatic
pressure (intravascular fluid volume expansion) and diminished vascular colloid osmotic
pressure (dilution).
Decreased osmotic pressure of blood
◦ loss of protein in urine (i.e. nephrotic syndrome)
◦ reduced synthesis of protein by liver (e.g. in cirrhosis)
◦ inadequate intake / absorption (malnutrition/ malabsorption)

Question 8

Describe the pathogenesis of oedema in heart failure

Answer 8

CARDIAC (‘pump failure’) (Details in cardiac failure section)
 Types
◦ LV failure
◦ RV failure
◦ biventricular failure
◦ Backward' failure = increased backward venous pressure ( oedema) ◦ Forward’ failure = inadequate output
 Mechanisms of oedema formation
◦ renin angiotensin/ aldosterone mechanism
◦ atrial naturietic factor depleted (from atrial walls)
◦ increased venous pressure

Question 9

Describe the pathogenesis of oedema in liver failure

Answer 9

Mechanisms of oedema formation
◦ fibrous scarring obstructs portal blood flow
◦ impaired albumin synthesis
◦ decreased renin degradation by liver
◦ renin/ aldosterone/ angiotensin mechanism

Question 10

Describe the pathogenesis of pathogenesis of oedema in kidney failure

Answer 10

KIDNEY (see renal pathology section)
 Nephrotic syndrome
◦ Mechanisms of oedema formation
▪ increased protein loss in urine  decreased osmotic pressure
▪ renin/ angiotensin / aldosterone mechanism
▪ ± superimposed renal vein thrombosis

Question 11

Categorize the different types of oedema.

Answer 11

Hypoxia in brain (and endothelial cells) so Na (and therefore H2O) passes into
◦ endothelial cells
◦ neurones and glial cells → intracellular oedema (maximal in cortex of brain)

Vasogenic oedema
Frank infarction of brain e.g. vascular disease (particularly atheroma), embolus, hypotension, abscess:
The fluid is extracellular (accumulation maximal in white matter

Hydrocephalic/ interstitial oedema
Obstruction to CSF outflow, fluid accumulates adjacent to the ventricles in the extracellular space
 blood brain barrier intact