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Body fluid, compartments and edema
The document discusses body fluids, fluid compartments, and edema. It notes that total body water is about 60% of body weight in adult males and 55% in females. Fluid balance is maintained through daily intake and output of water. The extracellular fluid volume makes up about 1/3 of total body water and is divided between interstitial fluid and plasma. Edema occurs when there is fluid accumulation from increased capillary pressure, decreased plasma oncotic pressure, increased capillary permeability, or lymphatic obstruction. Safety factors prevent edema from low tissue compliance, increased lymph flow, and washdown of interstitial proteins. Types of edema are classified by location such as generalized or localized edema.
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Body fluid, compartments and edema
- 1. BODY FLUID, COMPARTMENTSAND EDEMA Dr. Shefali Singhal 1
- 2. BODY FLUID Waterof the body together with its dissolved solute is called body fluid. Water is Essential constituent of all cells to maintain form, & texture of tissue, and to maintain body heat. Serves as transport medium, acts as medium of cellular reaction, solvent for vitamins, enzymes, electrolytes, non-electrolytes, hormones ect. Total body water is depends on age, gender and degree of obesity. In 70 kgs adult male TBW = 60% of total body wt. In female = 55% Newborn = 70 – 75% 2
- 3. WATER BALANCE Daily Intakeof Water Fluids Ingested (liquids/water in diet) – 2100 ml From metabolism – 200 ml Net Intake = 2300 ml Daily output of Water Skin – 350 ml lungs – 350 ml Sweat – 100 ml Feces – 100 ml Urine – 1400 ml Net Output = 2300 ml 3
- 4. Total body water (TBW) (70Kgs man) 40 Litres ECF volume 1/3 of TBW =14 Litres Interstitial fluid ¾ of ECF = 10.5 Litres Plasma ¼ of ECF = 3 Litres Transcellular fluid 0.5 Litres ICF Volume 2/3 of TBW = 28 Litres CSF Pleural Intraocular Synovial Peritoneal pericardial DISTRIBUTION OF BODY FLUID 4
- 5. MEASUREMENT OF FLUIDVOLUME Volume of any fluid compartment can be measured by placing a substance in the compartment by allowing it to disperse evenly & then measuring the extent to which the substance become diluted. Then a sample of the dispersed fluid is removed & the concentration of the substance is analyzed. The formula of measuring total body fluid= volume × concentration of the test substance injected concentration per ml of dispersed fluid 5
- 6. FEATURES OF IDEALINDICATOR Mix evenly Non toxic No effect of on the distribution of water or other substances in the body Relatively easy to measure. Must be unchanged and if changed must be known. 6
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- 8. BASIC PRINCIPLES THATMAINTAIN FLUID BALANCE BETWEEN ICF AND ECF The distribution of fluid between intracellular and extracellular compartments is determined mainly by the osmotic effect of smaller solutes across the cell membrane. The osmolality (300 mOsm/L) is determined mainly by: in ECF: Na+ and Cl- (80%) in ICF: K+ (50%) Corrected osmolar activity – due to interionic attraction b/w cation and anion, which causes a slight decrease in osmotic activity. Plasma has 1 mOsm/L greater osmolaity due to proteins. 8
- 9. BASIC PRINCIPLES THATMAINTAIN FLUID BALANCE BETWEEN ICF AND ECF CONTD. 9 plasma Interstitial fluid Intracellular fluid Total osmolality 299.8 mOsm/L 300.8 301.2 Corrected osmolar activity 282 mOsm/L 281 281 Osmotic pressure 5441 mmHg 5423 5423 •For each mOsml concentration gradient of an impermeant solute, about 19.3 mmHg of osmotic pressure is exerted across the cell membrane. •So relatively small changes in in the concentration of impermeant solute in ECF can cause large changes in cell volume.
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- 11. Vol – Osmolarity - Vol– Osmo- Vol – Osmo- Vol – Osmo- Vol – no change Vol – EFFECT OF ADDING DIFFERENT SOLUTION IN ECF AFTER OSMOTIC EQUILIBRIUM 11
- 12. Classification of disordersof water and sodium metabolism ECF volume HypervolumiaHypovolumia Adrenal insufficiency, diuretics Diabetes insipidus, Excessive sweating Hyponatremia Hypernatremia Serum Na+ concentration SIADH, Bronchogenic tumors Cushing syndrome, Primary aldosteronism (<130mmol/L) (>150mmol/L) 12
- 13. 1. HYPOVOLUMIC HYPONATREMIA 13 Characteristics:1) Loss of sodium more than water 2) Serum Na+ <130mmol/L 3) Plasma osmotic pressure< 280mmHg ETIOLOGY: 1. Renal loss of sodium • inappropriate long-term use of diuretics •Adrenocortical insufficiency •Renal disease 2. extra-renal loss of sodium •Via GI tract (diarrhea, vomiting) •Via skin (burn) •Body fluid accumulation in the third space (peritonitis)
- 14. 2. HYPERVOLUMIC HYPONATREMIA A hyponatremia with increased ECF volume, always associated with increased total body sodium and total body water, but the increase of water is greater than that of sodium. 14 Characteristics: 1) Serum Na+ < 130mmol/L 2) Plasma osmotic pressure < 280mmHg Etiology- (1). Excessive water intake- (2). Decreased Water loss- •Psychotic drinking •Excessive IV infusion of hypotonic solution •Acute renal failure •Over secretion of ADH Over retention of hypotonic fluid in the body
- 15. EFFECTS OF HYPONATREMIAON THE BRAIN AND ADAPTIVE RESPONSES 15
- 16. 3. HYPOVOLUMIC HYPERNATREMIA 16 Characteristics:1. Loss of water more than sodium 2. Serum Na+ >150mmol/L 3. Plasma osmotic pressure> 310mmHg Etiology : (1). Water intake (2). Water loss •Via GI tract – diarrhea, vomiting •Via skin – increase body temperature •Via kidney – DI, Osmotic diuresis ↓ ↑
- 17. 4. HYPERVOLUMIC HYPERATREMIA ECF volume expansion and hypernatremia coexist. 17 Causes: 1. Infusion of hypertonic salt solution to correct the hypotonic dehydration 2. primary hyperaldosteronism
- 18. Effects of hypernatremiaon the brain 18
- 19. EDEMA Edema: isthe accumulation of excessive body fluid in Fluid compartments or serous body cavity. Types: it can be intracellular or extracellular. 19 Intracellular Edema • Hyponatremia • Depression of tissue metabolic systems • Inadequate tissue nutrition • Inflammation of tissues (increased cell membrane permeability)
- 20. • Increased interstitialfluid volume • Causes:- 1) Increased Capillary Filtration 2) Failure of lymphatics to return interstitial fluid to circulation. Extracellular Edema Capillary Pressure (Pc) Plasma Colloid Osmotic Pressure (πc) Interstitial Fluid Pressure (Pif) Interstitial Colloid Osmotic Pressure (πif) Kf FILT = Kf (Pc - Pif - πc + π if) 17.3 mmHg 28 mmHg -3 mmHg 8 mmHg 20
- 21. PRINCIPALS OF EQUILIBRIUMOF FORCES ACROSS CAPILLARIES 21 Mean forces tending to move fluid outward- Mean capillary hydrostatic pressure 17.3 Negative interstitial free fluid pressure 3.0 Interstitial fluid colloid osmotic pressure 8.0 Total outward force 28.3 Mean force tending to move fluid inward- Plasma colloid osmotic pressure 28.0 Total inward force 28.0 NET FORCE -------- 0.3 (OUTWARD)
- 22. 1. INCREASED CAPILLARYHYDROSTATIC PRESSURE 22 Causes: •Elevated plasma volume – kidney failure, mineralocorticoid excess. •Increased venous pressure – - generalized venous pressure, i.e. congestive heart failure. - local venous pressure, i.e. venous thrombosis. -Failure of venous pump. •Arteriolar dilation i.e. acute inflammation, vasodilator drugs. ↑capillary hydrostatic pressure ↑force driving fluid into interstitium ↑formation of interstitial fluid edema When greater than lymphatic compensatory return Conditions Causing Edema
- 23. 2. DECREASED PLASMACOLLOID OSMOTIC PRESSURE 23 Causes: plasma protein decrease 2.5g/100mL ―Decrease of protein production i.e. hepatic cirrhosis, malnutrition ―Loss of protein in urine i.e. nephrotic syndrome ―Loss of protein from denuded skin area i.e. burns, wounds. ↓ plasma colloid osmotic pressure ↓force drawing water back into capillary from interstitium ↑formation of interstitial fluid edema When greater than lymphatic compensatory return
- 24. 3. INCREASED CAPILLARYPERMEABILITY 24 ↑capillary permeability Filtration of more protein from capillary to interstitium ↑formation of interstitial fluid edema When greater than lymphatic compensatory return ↓Plasma colloid osmotic pressure Causes: •Vitamin C deficiency •Infection •Burn •Allergic response •Trauma •ischemia
- 25. 4. OBSTRUCTION OFLYMPHATIC Fluid and proteins that filtered from capillaries into interstitium are return to the circulation by lymphatics. So, obstruction of lymphatic will result in edema. Causes: o Cancer o Infection, especially with filarial o Surgery o Congenital absence or abnormality of lymphatic vessels. 25
- 26. 1. LOW TISSUECOMPLIANCE AND NEGATIVE INTERSTITIAL FLUID HYDROSTATIC PRESSURE 26 Interstitial Volume Interstitial Fluid Hydrostatic Pressure Capillary Filtration •The interstitial fluid is bound in a proteoglycan meshwork so there are no large “free” fluid space. • Secondly, when the interstitial fluid pressure falls to very negative values, the gel does not contract greatly. • Thus, the compliance of the tissues is very low in the negative pressure range. Safety factors against edema
- 27. - 8 -4 0 + 4 12 24 36 48 60 0 InterstitialFluid Volume(liters) Interstitial Fluid Pressure (mmHg) Free Fluid Gel FluidLow compliance High Compliance Copyright © 2006 by Elsevier, Inc. Normal 27
- 28. 2. INCREASED LYMPHFLOW The lymphatics act as a safety factor against edema because lymph flow can increase to 10 to 50 folds when fluid begins to accumulate in tissue. This preventing the interstitial pressure from rising into the positive pressure range. 28 Interstitial Volume Interstitial Fluid Hydrostatic Pressure Lymph Flow
- 29. 3. “WASH-DOWN” OFINTERSTITIAL FLUID PROTEINS 29 Interstitial Volume Interstitial Fluid Oncotic Pressure Capillary Filtration Interstitial Fluid Hydrostatic Pressure Lymph Flow Protein Removal From interstitial space
- 30. Safety Factors AgainstEdema • Low compliance of interstitium when = 3 mmHg interstitial fluid pressure is negative • Increased lymph flow = 7 mmHg • “ Wash-down” of interstitial protein = 7 mmHg at high lymph flow rates Total Safety factor = 17 mmHg 30
- 31. TYPES OF EDEMA 31 Accordingto location a) Localized Venous edema, lymphatic edema, angioedema, inflammation b) Generalized Cardiac edema, hepatic edema, renal edema, endocrine edema According to clinical finding a) Pitting Due to cardiac and renal causes, liver disease b) Non-pitting Myxoedema, elephantiasis
- 32. Influencing factors ofedema 32 Factors Examples Gravity Cardiac edema: ankle Structure of tissue Renal edema: eyelids and face Local hemodynamics Hepatic edema: ascites
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