2. WHAT IS EDEMA?
• Abnormally increased accumulation of fluid in
the interstitial space.
• may be localised to one organ (e.g. abdomen-
ascites) or region or it may be generalised
(anasarca)
5. TYPES OF EDEMA
Venous edema
• low-viscosity, protein-poor
interstitial fluid.
• results from increased
capillary filtration
• normal lymphatic system
• pitting
lymphedema
• excess protein-rich
interstitial fluid.
• resulting from lymphatic
dysfunction.
• Usually non tender.
• a warty texture
(hyperkeratosis) is
characteristic of chronic
lymphedema.
• Usually non-pitting.
6. CAUSES OF VENOUS EDEMA
• High venous pressure (heart failure, venous pump
failure, venous obstruction)
• Excessive kidney retention of salt and water
• Decreased plasma proteins-
low intake: malnutrition
decreased production: liver disease
increased loss: nephrotic syndrome, burns
• Increased capillary permeability
7. CAUSES OF LYMPHEDEMA
• BLOCKAGE OF LYMPH RETURN
- infections (filarial nematodes)
- cancer
- surgery
- congenital absence or abnormality of
lymph vessels. (milroy’s disease)
If Jv is positive, then there is net fluid movement out of the capillary (filtration)
If Jv is negative, then there is net fluid movement into the capillary (absorption)
Kf- depends on the permeability of the capillary and is increased in inflammation states
Pc- Increases in Pc favors filtration out of the capillary.
It is determined by the arterial and venous pressures and resistances
An increases in either arterial or venous pressure will increase Pc but increases in venous pressure have a greater effect.
Pi- Increases in Pi oppose filtration out of the capillary. It is normally close to 0mmHg or negative)
Πc- Increases in πc oppose filtration out of the capillary
It is increased by increases in protein concentration in blood
πi - Increases in πi favour filtration out of the capillary
It is dependant upon the protein concentration of interstitial fluid
Its value is normally quite low because little protein is filtered out of capillaries into interstitial fluid
High venous pressure- Heart failure (systemic-right heart), venous pump failure (muscle paralysis, immobilization, valve failure), venous obstruction.
Kidney- Kidney failure and mineralocorticoid excess (aldosterone- increased Na and water reabsorption) .
Permeability – inflammation
Milroy’s disease- mutation of flt4 gene. Responsible for production of vascular endothelial growth factor. Mutation= malformed or absent lymphatic vessels= lymphmdema at birth.
Pulmonary edema: two types-
Cardiogenic- is caused by elevated pulmonary capillary hydrostatic pressure leading to transudation of fluid into the pulmonary interstitium and alveoli. Left sided heart failure increases pulmonary venous pressure and pressure in the lung microvasculature.
Non cardiogenic- fluid overload- renal, iatrogenic