Starling forces and capillary fluid exchange
Core concept
- Net filtration = Kf x [(Pc - Pi) - sigma(PIc - PIi)]
- Pc capillary hydrostatic - pushes fluid out
- PIc plasma oncotic (albumin) - holds fluid in
- Kf = permeability x surface area; sigma = reflection coefficient (protein leak)
Four routes to oedema
- inc Pc -> HF, fluid overload, venous obstruction, DHP CCBs
- dec PIc -> nephrotic, cirrhosis, malnutrition, protein-losing enteropathy
- inc Kf / dec sigma -> sepsis, burns, anaphylaxis, IL-2 (capillary leak)
- Lymphatic obstruction -> malignancy, nodal dissection, filariasis
3 more sections, plus exam facts
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