Oedema**

Question 1

Oedema definition

Answer 1

Excessive fluid in the interstitium.

Question 2

Causes of oedema.

Answer 2

• Acute inflammation

As well as haemodynamic causes:

• Increased hydrostatic pressure
• Reduced colloid osmotic pressure
• Sodium-water retention
• Lymphatic obstruction

Question 3

Mechanisms by which acute inflammation causes oedema

Answer 3

Increased permeability to both protein and water results in an exudate (fluid with specific gravity >1.020).

Question 4

Causes of increased hydrostatic pressure

Answer 4

Impaired venous return

• Congestive heart fialure
• Impaired venous return due to compression or obstruction
• Constrictive pericarditis
• Ascites due to liver cerrhosis
• Lower extremity inactivity with prolonged dependency
• Pregnancy

Question 5

Causes of reduced colloid osmotic pressure

Answer 5

• Protein loss due to nephrotic syndrome
• Protein loss due to malabsorption/low intake
• Failure of protein synthesis due to liver disease

Question 6

Causes of sodium/water retention

Answer 6

• Acute renal failure
• Disturbance of renin-angiotensin-aldosterone system
• Secondary to cardiac failure or hypoproteinaemia

Question 7

Causes of lymphatic obstruction

Answer 7

1. Inflammatory
2. Neoplastic
3. Post surgical
4. Post irradiation

Question 8

When do transudate and exudate occur? What is the difference.

Answer 8

Exudate is a fluid with a specific gravity >1.020 which contains protein and water. It occurs during accute inflammation.

Transudante has a specific gravity of <1.020 and has a low protein content. It occurs during haemodynamic disturbance.

Question 9

Effects and outcomes of oedema

Answer 9

The effects depend on te location and the time course

Pulmonary and cerebral oedema are clinical emergencies.