Edema

Description

• Clinically apparent accumulation of excess fluid in the interstitial compartment due to imbalances in capillary oncotic and hydrostatic drainage:
  • Increase in venous/capillary hydrostatic pressure
  • Decrease in plasma oncotic pressure
  • Increase in interstitial oncotic pressure
  • Increase in capillary permeability
  • Increase in lymphatic pressure due to obstruction
  • Combination of these factors
• Generalized, as with CHF or nephrotic syndrome
• Localized, as with deep vein thrombosis
• Increased venous hydrostatic pressure or decreased oncotic pressure results in pitting edema
• Protein-rich extravasated fluid results in nonpitting edema
• In certain disorders, there is no clear relation to Starling forces:
  • Idiopathic (cyclic) edema:
    • Worsened with heat
    • More common in women
    • Not necessarily related to menses
• Inflammatory states (burns, sepsis, allergic reactions) cause capillary leakage due to cytokine-mediated changes
• Lymphedema: Protein-rich fluid accumulation due to impaired lymphatic drainage
• Conditions like heart failure, cirrhosis, and nephrotic syndrome activate the renin–angiotensin–aldosterone system (RAAS), leading to sodium retention and exacerbating edema
• Peripheral edema is common, affecting up to 20% of adults over 50
• More common in older adults, particularly women with chronic venous insufficiency or lymphedema

Etiology