Oedema & Lymphoedema Flashcards Preview

ESA 1 - Body Logistics > Oedema & Lymphoedema > Flashcards

Flashcards in Oedema & Lymphoedema Deck (16):
1

What is the difference between oedema and lymphoedema?

- Oedema = accumulation of an excessive amount of watery fluid in cells, tissues or serous cavities.
- Lymphoedema = swelling (esp. in subcutaneous tissue) as a result of obstruction of lymphatic vessels or lymph nodes and the accumulation of large amounts of lymph in the affected region.

2

How can one differentiate between oedema and lymphoedema?

- Swelling does not pit in lymphoedema.
The lymphatic obstruction prevents drainage of water and proteins from the IS - increased protein content in IS stimulates inflammatory response - proliferation of fibroblasts and change in organisation of fluid space.

- Swelling pits in oedema.
Pressing temporarily increases hydrostatic pressure, pushing fluid out of the IS.

3

What determines the movement of fluid in/out of capillaries?

Starling forces:
1. Hydrostatic pressure gradient
2. Oncotic pressure gradient
3. Vascular permeability

4

What is vascular permeability?

Histological architecture of capillaries determines permeability of capillaries to water.

5

What is the hydrostatic pressure gradient?

Physical force of fluids against their enclosing barriers.
- positive for plasma within capillaries (remnant of blood pressure generated by heart) though declines towards the venal side due to resistance to blood flow generated by capillary
- negative for interstitial fluid within IS due to action of lymphatic pumping

6

What is the oncotic pressure gradient?

Osmotic pressure generated by the presence of proteinaceous solutes.
Higher in plasma than in IS as plasma proteins cannot cross the capillary barrier.

7

What is the arteriolar and venular capillary hydrostatic pressures and the blood colloid oncotic pressure?

- 35 mmHg
- 15 mmHg
- 25 mmHg

8

What is the consequence of pathological processes disturbing the Starling Forces?

Excessive water filtration out of capillaries leading to localised or generalised oedema.

9

What are the causes and consequences of derangement of hydrostatic pressure gradient?

Causes:
- venous thrombosis
- right heart failure

Consequences: ineffective venous drainage of blood - backup of blood - increased hydrostatic pressure on venous side (congestion) - oedema.

10

What are the causes and consequences of derangement of oncotic pressure.

Causes:
- Cirrhosis
- Nephrotic syndrome

Consequences: poor synthesis or excessive loss of plasma proteins (esp. albumin) - reduced plasma oncotic pressure - oedema.

11

What are the causes of derangement of vascular permeability?

Damage of tight architecture of capillaries can occur due to immune-mediated processes in acute inflammation or due to thermal damage in burns.

12

Where does oedema usually first appear?

- At the ankles because gravity in the upright human body can cause a vertical gradient of venous pressures.
- Sacral oedema in someone lying/sitting.

13

What is the likely cause of oedema when ankle swelling is absent at the beginning of the day but appears later on?

- Venous pressure problems

14

What is the likely cause of oedema if ankle swelling is unilateral?

- DVT
- Venous insufficiency
- Lymphoedema
- Lack of muscle use (e.g. OA in 1 knee so decreased pressure)
- Cellulitis (inflammatory cells in interstitium - increased protein content - fluid build-up)

15

Where is oedema likely to appear in patients with hypoproteinaemia (nephrotic syndrome)?

- Periorbital oedema often appears first thing in the morning.
- Negative pressure in head when lying so increased venous pressure, and lax skin around eyelids provides swelling space.

16

Why might venous hypertension cause haemosiderin staining?

Heart failure - increased venous hypertension - perforates capillaries - erythrocytes enter intersitium and are engulfed by macrophages.
But 1 erythrocytes contains 270 million haemoglobin molecules. Redox reaction from ferrous oxide to ferric oxide inside lysosomes - rust production and skin staining.