MEDI7212 Lecture Notes - Lecture 20: Lymphadenectomy, Aureus, Ascites
Document Summary
Introduction: oedema is the accumulation of serous fluid in intracellular tissue resulting from abnormal expansion in interstitial fluid volume. Local or systemic conditions disrupt the equilibrium between interstitial and intravascular spaces normally regulated by capillary hydrostatic pressure gradient & oncotic pressure gradient across capillary. Increased capillary hydrostatic pressure, increased plasma volume, decreased plasma oncotic pressure (hypoalbuminemia), increased capillary permeability or lymphatic obstruction: physiology. Arterial end - hydrostatic > oncotic, blood leaks out of capillary. Venous end - oncotic > hydrostatic, interstitial fluid back into capillary. Capillary membrane: permeable to electrolytes and water, permeable to smaller proteins (eg insulin, not readily permeable to larger proteins (eg albumin) Oncotic pressure: capillary hydrostatic pressure is pressure of plasma against capillary wall. It pushes fluid from capillaries ---> interstitial space. Interstitial hydrostatic pressure is the pressure of interstitial fluid against capillary wall. Increased na and h2o retention: kidney failure, heart failure, mineralocorticoid excess.
