Body fluid, compartments and edema

1. BODY FLUID, COMPARTMENTS AND
EDEMA
Dr. Shefali Singhal
1

2. BODY FLUID
 Water of 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%
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3. WATER BALANCE
Daily Intake of 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)
(70 Kgs 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
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5. MEASUREMENT OF FLUID VOLUME
 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
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6. FEATURES OF IDEAL INDICATOR
 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.
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7. 7

8. BASIC PRINCIPLES THAT MAINTAIN 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.
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9. BASIC PRINCIPLES THAT MAINTAIN 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.

10. BODY FLUID COMPOSITION
10
mOsm/L H2O

11. Vol –
Osmolarity -
Vol –
Osmo-
Vol –
Osmo-
Vol –
Osmo-
Vol – no change Vol –
EFFECT OF ADDING DIFFERENT SOLUTION IN
ECF AFTER OSMOTIC EQUILIBRIUM
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12. Classification of disorders of 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)
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13. 1. HYPOVOLUMIC HYPONATREMIA
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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.
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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 HYPONATREMIA ON THE BRAIN AND
ADAPTIVE RESPONSES
15

16. 3. HYPOVOLUMIC HYPERNATREMIA
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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.
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Causes:
1. Infusion of hypertonic salt solution to correct the hypotonic
dehydration
2. primary hyperaldosteronism

18. Effects of hypernatremia on the brain
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19. EDEMA
 Edema: is the accumulation of excessive body fluid in
Fluid compartments or serous body cavity.
 Types: it can be intracellular or extracellular.
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Intracellular Edema
• Hyponatremia
• Depression of tissue metabolic systems
• Inadequate tissue nutrition
• Inflammation of tissues (increased cell
membrane permeability)

20. • Increased interstitial fluid 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
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21. PRINCIPALS OF EQUILIBRIUM OF
FORCES ACROSS CAPILLARIES
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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 CAPILLARY HYDROSTATIC PRESSURE
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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 PLASMA COLLOID OSMOTIC
PRESSURE
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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 CAPILLARY PERMEABILITY
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↑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 OF LYMPHATIC
 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.
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26. 1. LOW TISSUE COMPLIANCE AND NEGATIVE
INTERSTITIAL FLUID HYDROSTATIC PRESSURE
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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
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28. 2. INCREASED LYMPH FLOW
 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.
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Interstitial
Volume
Interstitial Fluid
Hydrostatic Pressure
Lymph Flow

29. 3. “WASH-DOWN” OF INTERSTITIAL FLUID
PROTEINS
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Interstitial
Volume
Interstitial Fluid
Oncotic Pressure
Capillary Filtration
Interstitial Fluid
Hydrostatic Pressure
Lymph Flow
Protein Removal
From interstitial
space

30. Safety Factors Against Edema
• 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
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31. TYPES OF EDEMA
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According to 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 of edema
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Factors Examples
Gravity Cardiac edema: ankle
Structure of tissue Renal edema: eyelids and face
Local hemodynamics Hepatic edema: ascites

33. THANK YOU
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