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Cardiovascular Physiology
Edema Formation
1. What is edema?
Edema is excessive fluid accumulation in interstitial spaces.
2. Where does edema develop?
Edema can develop in any organ or collect as free fluid in body cavities (such as ascites, pleural effusion, pericardial effusion)
3. What factors promote the development of edema?
Edema occurs because of either:
  • Excessive fluid filtration out of capillaries, which can be due to either:
    • Elevated hydrostatic pressure usually due to heart failure (see Starlings Forces) or over-hydration
    • Reduced plasma colloid osmotic pressure (hypoproteinemia) which itself can be due to:
      • Excessive protein loss from the kidneys or bowel
      • Reduced production from the liver
    • Increased capillary membrane permeability

  • Lymphatic obstruction
  • production