Tissue fluid formation & Edema slideshare

TISSUE FLUID FORMATION AND EDEMA PPT

1. Tissue fluid formation & Edema Dr Anu Priya J

2. Introduction Tissue fluid / Interstitial fluid is the fluid which occupies the intercellular spaces. A medium for the exchange of substances such as nutrients, O 2 , CO 2 , metabolic wastes, etc., between the cells and blood.

3. Role of capillaries Fluid exchange between intravascular and interstitial compartments occurs only at the level of capillaries. The other parts of the vascular system are impermeable. The capillaries are permeable because they are lined by a single layer of flattened endothelium.

4. Formation of tissue fluid Tissue fluid is derived from two sources: From blood capillaries From metabolism in tissues

5. Formation of tissue fluid Factors affecting the formation of tissue fluid: Permeability of capillaries Diffusion Filtration and reabsorption Metabolic activity of tissues

6. Filtration & Reabsorption Most important mechanism by which tissue fluid is formed. Fluid is filtered out at the arterial end of the capillary & is reabsorbed at its venous end. Starling’s forces regulate the movement of fluid into and out of the capillaries. Formation of tissue fluid

7. Drainage of tissue fluid 85% reabsorbed in the venular end of capillary 15% drained via lymph

8. Starling’s forces Hydrostatic pressure in capillary (Pc) Hydrostatic pressure in interstitium (Pi) Colloidal osmotic pressure/ Oncotic pressure in capillary ( π c ) Colloidal osmotic pressure/ Oncotic pressure in interstitium( π i ) Formation of tissue fluid

9. Formation of tissue fluid

10. Starling’s forces Filtrative force = Hydrostatic pressure gradient (Pc – Pi) Absorptive force = Oncotic pressure gradient ( π c - π i ) Formation of tissue fluid

11. Starling’s forces Nf = Kf [(Pc – Pi) - ( π c - π i ) Kf = Permeability x Surface area Nf - Net filtration force Kf - Permeability coefficient Formation of tissue fluid

12. Formation of tissue fluid Pc 37 mmHg Pc 17 mmHg π c 25 mmHg π i 0 mmHg Pi 1 mmHg Hydrostatic pressure Hydrostatic pressure Arteriolar end of capillary Venular end of capillary

13. Arteriolar end: Net filtration force = +11mmHg Hydrostatic pressure gradient > Oncotic pressure gradient Filtration of fluid Venular end: Net filtration force = (-9mmHg) Hydrostatic pressure gradient < Oncotic pressure gradient Absorption of fluid Formation of tissue fluid

14. Edema Accumulation of abnormally large amount of fluid in the interstitial spaces Pathophysiology of edema Increased filtration of fluid Inadequate drainage of fluid

15. Etiology / Causes Based on etiology : Cardiac edema Renal edema Inflammatory edema Noninflammatory -Giant/ angioneurotic edema Heat edema Lymphedema Edema due to malnutrition Edema due to liver disease Edema due to venous obstruction

16. Types of edema Based on location Based on response to pressure

17. Types of edema Based on location Localised edema Generalised edema

18. Types of edema Based on response to pressure Pitting edema pit/ intendation seen after 30s pressure – due to displacement of fluid from the area of pressure Inflammation, Congestive cardiac failure(CCF), Renal diseases etc., Nonpitting edema Conditions where the swelling is not chiefly due to fluid collection Myxedema, Lymphedema in filariasis, etc.,

19. Edema in liver disease Hypoproteinemia due to decreased synthesis of proteins - decreased oncotic pressure in the capillaries – reabsorptive force lesser than the filtration force – accumulation of fluid in the interstitial spaces - edema

20. Edema in renal failure H ypoproteinemia due to proteinuria – decreased oncotic pressure in the capillaries – reabsorptive force lesser than the filtration force– accumulation of fluid in the interstitial spaces - edema

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