Oedema & Lymphoedema Flashcards Preview

ESA 1 - Body Logistics > Oedema & Lymphoedema > Flashcards

Flashcards in Oedema & Lymphoedema Deck (16)
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1
Q

What is the difference between oedema and lymphoedema?

A
  • 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
Q

How can one differentiate between oedema and lymphoedema?

A
  • 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
Q

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

A

Starling forces:

  1. Hydrostatic pressure gradient
  2. Oncotic pressure gradient
  3. Vascular permeability
4
Q

What is vascular permeability?

A

Histological architecture of capillaries determines permeability of capillaries to water.

5
Q

What is the hydrostatic pressure gradient?

A

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
Q

What is the oncotic pressure gradient?

A

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

7
Q

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

A
  • 35 mmHg
  • 15 mmHg
  • 25 mmHg
8
Q

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

A

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

9
Q

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

A

Causes:

  • venous thrombosis
  • right heart failure

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

10
Q

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

A

Causes:

  • Cirrhosis
  • Nephrotic syndrome

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

11
Q

What are the causes of derangement of vascular permeability?

A

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

12
Q

Where does oedema usually first appear?

A
  • 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
Q

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

A
  • Venous pressure problems
14
Q

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

A
  • 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
Q

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

A
  • 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
Q

Why might venous hypertension cause haemosiderin staining?

A

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.