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Leicester Warwick Medical School

Leicester Warwick Medical School. Tissue Fluid Formation and Oedema Dr. Kevin West kpw2@le.ac.uk Department of Pathology. Tissue Fluid Formation - Objectives 1. Control of normal interstitial fluid formation Definition of oedema

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Leicester Warwick Medical School

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  1. Leicester Warwick Medical School Tissue Fluid Formation and Oedema Dr. Kevin West kpw2@le.ac.uk Department of Pathology

  2. Tissue Fluid Formation - Objectives 1 • Control of normal interstitial fluid formation • Definition of oedema • Definition of pleural effusion, pericardial effusion and ascites • Distinction between transudate and exudate

  3. Tissue Fluid Formation - Objectives 2 • Common causes and mechanisms of development of oedema • Pulmonary oedema - causes and effects • Cerebral oedema - causes and effects

  4. Water • Major body component • 60% male 50% female • 3 compartments • intracellular • extracellular interstitial • extracellular intravascular

  5. Osmolality • Osmotic pressure related to number of particles of solute • Oncotic pressure describes osmotic pressure exerted by proteins • Effect of oncotic pressure small but significant across capillaries

  6. Control of Interstitial Fluid • Hydrostatic pressure • Oncotic pressure • Endothelial integrity • Lymphatic system

  7. Interstitial Fluid • Fluid between cells • Derived from capillaries • Solutes similar to plasma except for protein content

  8. Movement Of Fluid Across Capillaries • Capillary (hydrostatic) pressure • Interstitial fluid (hydrostatic) pressure • Plasma oncotic pressure • Interstitial fluid oncotic pressure

  9. Capillary Pressure • Forces fluid from capillary to interstitium • Arterial end higher than venous end • Arterial approx. 30 mmHg • Venous approx. 10 mm Hg

  10. Interstitial Fluid Pressure • Maybe positive or negative • Negative - forces fluid into interstitium • Positive - forces fluid into capillary • Approx. minus 3 mm Hg in loose connective tissue • Higher in denser connective tissue

  11. Plasma Oncotic Pressure • Proteins are the only solutes which do not pass freely between plasma and interstitium • Thus it is only proteins which exert a significant osmotic effect across capillary walls • Albumin is the most abundant plasma protein • Approx 28 mm Hg (Albumin = 21.8)

  12. Interstitial Oncotic Pressure • A small amount of protein is present in the interstitium • Tends to force fluid out of capillary • Concentration is approx 40 % of that in plasma • Approx 8 mm Hg

  13. Outward Cap. pressure 30 Negative interstitial fluid pressure 3 Interstitial oncotic pressure 8 Total 41 Inward Plasma oncotic pressure 28 Net out 13 (Filtration pressure) Balance Sheet - Arterial

  14. Outward Cap. pressure 10 Negative interstitial fluid pressure 3 Interstitial fluid oncotic presure 8 Total 21 Inward Plasma oncotic pressure 28 Net inward 7 (Reabsorption pressure) Balance Sheet - Venous

  15. Lymphatic System • The lymphatic system provides a route for the transport of fluids and protein away from the interstitium • System of fine lymphatic channels throughout the body passing via lymph nodes to thoracic duct • Valves ensure one-way flow

  16. Oedema • Hydrostatic pressure • Oncotic pressure • Endothelial integrity • Lymphatic integrity

  17. Oedema • Definition An increased volume of interstitial fluid in a tissue or organ May be localised or generalised (systemic)

  18. Causes of Oedema • Raised capillary pressure • Reduced oncotic pressure • Endothelial damage (inflammation) • Impaired lymphatic drainage

  19. Raised Capillary Pressure • Cardiac failure • right ventricular failure - systemic oedema • left ventricular failure - pulmonary oedema • congestive cardiac failure - both • Local venous obstruction • deep vein thrombosis • external compression • SVC obstruction

  20. Reduced Oncotic Pressure • Renal disease • loss of albumin across glomerulus • Hepatic disease • inadequate albumin synthesis • Malnutrition • inadequate albumin synthesis

  21. Lymphatic Obstruction • Tumours • Fibrosis • Inflammation • Surgery • Congenital abnormality

  22. Generalised Oedema • Congestive cardiac failure • Right ventricular failure • Renal disease • Liver disease

  23. Generalised Oedema • Commonly causes swelling of ankles • Swelling may extend higher • Sacral oedema in recumbent patients

  24. Right Ventricular Failure • Raised jugular venous pressure also seen • Enlarged liver also common due to congestion (nutmeg liver)

  25. Pulmonary Oedema • Usually caused by LVF • Raised pressure across pulmonary capillaries • Causes shortness of breath • Due to ischaemic heart disease or hypertension

  26. Pulmonary Oedema

  27. Congestive Cardiac Failure • Combination of left and right ventricular failure • Common in ischaemic heart disease • Causes systemic and pulmonary oedema

  28. Cerebral Oedema • Causes increased intracranial pressure • Fatal if left untreated • Generalised in hypoxia, injury • Surrounding other lesions eg tumour, abscess

  29. Fluid in Body Cavities • Pleural effusion • heart failure, inflammation, tumour • Pericardial effusion • inflammation, tumour • Ascites (peritoneal effusion) • cirrhosis, heart failure, tumour

  30. Pleural Effusion

  31. Pericardial Effusion

  32. Ascites • Most severe cases associated with • cirrhosis of the liver • intra-abdominal malignancy

  33. Superior Vena Cava Obstruction

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