Fluid

1
Fluid Electrolyte balance
Dr M A Maleque Molla FRCP(ED), FRCPCH

• October 22, 2014

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Pre review test

• What percentage of body wt of an infant is
  water?
• A. 25
• B. 30
• C. 60
• D. 65

• Answer D

3

• 2. Major cation in the ECF is
• Potassium
• Calcium
• Sodium
• Magnesium

Answer C
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• 3. Homeostasis of body water and electrolytes
  are made by all the hormone except
• ADH
• Aldosterone
• Atrial natriuretic peptide
• Cortisol

• Answer D

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Body Composition

• Fluid 60
• Solid 40
• Fat
• Protein
• Carbohydrate
• Minerals

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Distribution of body fluids (by wt)

• Fluid 60 of BW
• Itracellular
• Extracellular
• Intrstitial
• Intra vascular(plasma)

There is continuous ongoing equilibrium between
the intracellular and extracellular spaces.
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Fluid content according to age

• Total body water (TBW) vary with age
• Preterm 80-85
• Term 75
• Infant 65
• Older children adult male 60
• Adult female50

• TBW ? to 60 by 1st yr of life
• Female has less fluid content because of more fat
  cells

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Effective circulating volume (ECV)

• Def Portion of the ECF that take part in tissue
• perfusion.
• Only 5 of TBW (intra vascular fluid) are ECV
• Adequate ECF must be maintained all the times

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Composition of body fluid

• Water
• Electrolytes Inorganic salts, Sodium(Na),
  Potassium(K), Calcium (Ca), Chloride(Cl),
  Phosphate(Po4), Bicarbonate(HCO3, Sulphate(SO4)
• Nonelectrolytes Minerals -iron and zinc,
  Glucose, Lipids, Creatinine, Urea

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Electrolytes of body fluid

• Electrolytes are measured in mEq or mmol
• Circulating electrolytes electrically charged
• When positively charge called cation Na, K,
  Ca
• When negatively charge called anions Cl-
  ,HCO3-, SO4-

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Electrolytes composition of body fluids

• Normal Values(serum)
• Cation
• Sodium (Na) 135 145 mEq/L
• Potassium (K) 3.5 5.50 mEq/L
• Calcium (Ca) 8.5 10.5 mg/dL
• Ionized Calcium 4.5 5.5 mg/dL
• Magnesium (Mg) 1.5 2.5 mEq/L
• Anion
• Bicarbonate (HCO-3) 24 30 mEq/L
• Chloride (Cl--) 95 105 mEq/L
• Phosphate (PO4---) 2.8 4.5 mg/dL

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Na 140
K 140
Cl- 140
Phos- 107
INTRA CELLULAR FLUID
EXTRA CELLULAR FLUID

• Distribution of Cation and Anion in ECF ICF
  (mEq/l)

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Fluid Electrolyte balance?

OUT PUT
INTAKE
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Daily physiological fluid balance

• INTAKE
• Ingested liquid 1500 ml
• Ingested food 800 ml
• Metabolism 200 ml
• Total 2500 ml/day

• OUTPUT
• Kidney 1500 ml
• Skin loss 600 ml
• GI 100 ml
• Lung 300 ml
• Total 2500 ml

Daily fluid balance of an adult
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Movement of fluid electrolytes

• A. Passive transport (no energy required)
• Osmosis Fluid move from higher concentration to
  lower concentration
• Diffusion Molecules move from higher
  concentration to lower (Concentration gradient)
• Filtration Fluid and diffusible substances
  move together across a membrane moving from ?
  pressure to ? pressure
• Hydrostatic pressure Fluids moves from an area
  of higher pressure to area of lower pressure
• B. Active transport( energy required)
• Sodium-Potassium Pump

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Concentration of Body fluid

• Units of solute concentration are osmolarity and
  osmolality
• Osmolarity Number of osmoles of solute per liter
  (L) of solution. It is expressed as osmol/L
• e.g 1 mol/L NaCl solution has an osmolarity of
  2 osmol/L
• Osmolality Number of osmoles of solute per
  kilogram(kg) of solvent. It is expressed as
  osmol/kg
• Normal serum osmolality280-298 mosmol/kg

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Clinical relevance of osmolality

• Calculation
• Serum osmolality (mosmol/kg)
• Effective osmolality Osmotic force that is
  mediating the shift of water between the ECF and
  the ICF
• The osmotic gap (osmolal gap) is the difference
  between the actual osmolality (measured by the
  laboratory) and the calculated osmolality
• A normal osmolal gap is lt 10 mOsm/kg

2(Na K) mmol/l Urea (mmol/l) Glucose
(mmol/l)
2 x Na (mmol/l ) Glucose (mmol/l)
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Regulation of Body Fluids

• Body fluid Homeostasis is maintained through
• Fluid intake
• Hormonal regulation
• Antidiuretic hormone(ADH)
• Renin-Angeotensin-Aldosterone Mechanism
• Natriuretic Peptides
• Fluid output

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A. Fluid intake

• Intake is control by hypothalamic thirst center

• ? plasma osmolality
• of 12
• ? plasma volume
• 1015
• Baroreceptor input,
• angiotensin II, and
• other stimuli

-Ve

• Moistening of the mucosa of the mouth and throat
• Activation of stomach and intestinal stretch
  receptors

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1. Antidiuretic hormone(ADH)
B. Hormonal regulation

• ADH Secreted by the hypothalamus, and stored in
  the posterior pituitary gland
• ADH is released by, thrust, ? fluid volume, High
  serum osmolality
• Acton
• reabsorb water from collecting duct of kidney
• inhibit sweat glands to ? perspiration to
  conserve water
• acts on arterioles, causes constriction thus ?
  BP
• ADH is Inhibited by
• Excessive of fluid volume
• Low osmolality of serum

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2. Renin- Angiotensin-Aldosterone Mechanism

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3. Natriuretic Peptides

• Natriuretic Peptides
• Atrial Natriuretic Peptide(ANP ) from atria
• Brain Natriuretic Peptide(BNP) from ventricle
• Action
• Acts like a diuretic that causes sodium loss and
  inhibits the thirst mechanism
• Inhibit rennin release
• Inhibit the secretion of ADH and aldosterone
• Vasodilatation

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C. Regulation by fluid output

• Daily fluid losses 2500 ml for an adult
• Kidney(Urine) 55
• Skin 30
• Lung 10
• GI (Stool) 2-5

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Renal handling of Fluid Electrolytes
Substance Filtered Excreted Net reabsorption
Water 180 L 1.5 L 98-99
Na 26,000 mmol 100-250 mmol gt99
Cl- 21,000 mmol 100-250 gt99
K 800 mmol 40-120 mmol gt85-95
HCO3_ 4,800 mmol 0 mmol 100
Urea 54 gm 27-32 g 40-50
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• Regulation of Electrolytes

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Regulation of Sodium Water

• Major cation in the ECF (N135 - 145 mEq/L)
• Combines with chloride and bicarbonate to help
  regulate acid-base balance
• Recommended daily in take 2.5gm/day
• Kidney regulates sodium balance and is the
  principal site of sodium excretion
• Aldosterone helps in sodium and water
  conservation

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Potassium regulation

• Major electrolyte and principle cation in the ICF
• Regulates metabolic activities
• Required for glycogen deposits in the liver and
  skeletal muscle
• Required for transmission of nerve impulses,
  normal cardiac conduction and normal smooth and
  skeletal muscle contraction
• Daily intake 1-2 mEq/kg
• Regulated by dietary intake and renal excretion
• Intestine absorbs about 90 of ingested
  potassium
• Regulate by renin-angiotensin-aldosterone
  mechanism

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Calcium regulation

• 99 of calcium is in the bones and teeth
• 1 is in ECF
• 50 of calcium in the ECF is bound to protein
  (albumin)
• 40 is free in ionized form-Ionized calcium
• Ca is needed for
• Bone and teeth formation
• Blood clotting
• Hormone secretion
• Cell membrane integrity
• Cardiac conduction
• Transmission of nerve impulses
• Muscle contraction

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Anions

• Chloride (Cl-)
• Major anion in ECF
• Follows sodium
• Bicarbonate (HCO3-)
• Is the major chemical base buffer required for
  acid base balance
• Is found in ECF and ICF
• Regulated by kidneys

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Maintenance replacement therapy

1. Maintenance therapy Replacement of daily
   physiologic losses of water and electrolytes
   under normal condition
2. Replacement therapy Replacement of abnormal loss

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Maintenance fluid requirement

• Water requirements are directly related to
  caloric energy expenditures
• Daily caloric expenditure water requirement
  depends on weight of the children
• For first 10 kg of wt spend 100 kcal/kg needs
  100 ml/kg of water
• Second 10 kg of wt spend 50 kcal/kg needs
  50ml/kg of water
• gt20 kg up to 80 kg, spends 20 kcal/kg needs 20
  ml/kg of water

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Calculation of daily maintenance fluid

• Daily Basis
• Wt 1-10 kg 100 ml/kg
• Wt 11 to 20 kg 50 ml/kg
• Wt gt20 kg up to 80 kg20 ml/kg
• Maximum 2400 ml/day.

Holliday-Segar Method
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Maintenance fluid requirement

• Daily losses in normal condition 100ml/100kcal
• Sensible losses 60
• Urine 55- 55 ml/100kcal
• Stool 5- 5 ml/100 kcal
• Insensible losses 40
• Skin 30 -30ml/100 kcal
• Lung 10 -10 ml/100 kcal
• Insensible loss increase Fever-by 10-12 per 1
  0C above 37.8 0C, tachypnea by 10-30

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Daily maintenance electrolyte requirement

• Sodium 2 - 3 mmol/100ml H2O /day
• Potassium 1 - 2 mmol/100ml H2O /day
• Chloride 2 - 3 mmol/100ml H2O /day

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Maintenance therapy
Example A child is comatosed, not dehydrated.
Vital signs stable. wt 25 kg. outline his fluid
management plan.

• Fluid requirement
• First 10 kg 10 x 100 1000 ml
• Second 10 kg 10 x 50 ml 500 ml
• Rest 5 kg 5 x 20 ml/kg100 ml
• Total 1600 ml/day.

• Electrolytes requirements
• Sodium 16 x 3 48 mmol/day
• Potassium 16 x 2 32 mmol/day
• Chloride 16 x 2 32 mmol/day

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What types of IV fluid ?

• Types of IVF used
• Normal saline (0.9 NaCl/L) 154 mEq Na/L
• One-half NS (0.45 NaCl/L) 77 mEq Na/L
• One-third NS (0.33 NaCl/L) 57 mEq Na/L
• One-quarter NS (0.25 NaCl/L) 38 mEq Na/L
• One fifth NS(0.18 Nacl) 30 mmol/l
• Ringers lactate Na 130 mmol/l, K 4 mmol/l,
  Cl- 109 mmol/l, bicarb 28 mmol/l , and Ca 3
  mg/dl )
• Q. What type of fluid to be used for the child of
  25 kg for
• maintenance?

• Maintenance fluid for the child wt 25 kg-D5 ¼ th
  NS with 20 meq potassium/liter will be adequate

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Fluid Imbalance

• Fluid deficit -Dehydration
• Fluid excess- Hypervolemia

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Dehydration

• Abnormal fluid loss causes fluid deficit called
  dehydration
• Conditions can leads to dehydration
• Skin Fever, under heater, heat exhaustion, burn
• GI Gastroenteritis, fistula, intestinal
  obstruction
• Lung Tachypnea
• Kidney Polyuria e.g. diabetes
• Miscellaneous Surgical drain, third spacing

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Severity of dehydration

• According to severity
• Mild dehydration -3-5 loss of BW
• Moderate dehydration-6-9 loss of BW
• Severe dehydration- 10 loss of BW

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Clinical features of dehydration
From Lissauer Graham 2002
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Signs Symptoms MILD MODERATE SEVERE
Wt Loss 3-5 6-9 gt10
General condition Well, alert Irritable Lethargic/floppy
Thirst Thirsty Drinks eagerly Unable to drink
Oral mucous Slightly dry Dry Parched
Ant fontanel Normal Depressed Depressed
Eyes Normal Sunken Sunken
Skin turgor Skin pinch retracts Normal Normally Depress in gt2 sec Tenting Takesgt3 sec
Urine output Normal Decrease No urine
Pulse Normal Rapid Rapid weak
Respiration Normal Deep Deep Rapid
BP Normal Normal Decrease
Capillary refill time Normal 2 Sec gt 3 sec

Clinical assessment of severity of dehydration
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Types of dehydration

• According to serum Sodium (Na) concentration
• Isonatremic (Isotonic)S. Na 135-150 mmol/l
• Hyponatremic (Hypotonic) S. Na lt135 mmol/l
• Hypernatremic (Hypertonic) S. Nagt150 mmol/l

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Management of dehydration

• Fluid therapy
• Enteral
• Oral rehydration therapy
• By NGT
• Parenteral
• Intravenous

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Management of dehydrationOral rehydration
therapy (ORT)

• Indication
• Mild moderate dehydration due to
  gastroenteritis
• Relative Contra indication
• Shock
• Altered mental status
• Severe dehydration
• Parental limitations
• Excessive vomiting
• Abdominal distention or absent bowel sounds

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Composition of different types of ORS other
solution
Solution Glucose Mmol/l Na Mmol/l Cl Mmol/l K Mmol/l HCO3 Mmol/l Osmolality
WHO 1975 111 90 80 20 30 310
WHO 2002 75 75 65 20 30 245
Pedialyte 140 45 35 20 30 250
Rehydrate 140 75 65 20 30 310
Cola 700 2 2 0 13 750
Apple juice 690 3 32 0 730
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Management of dehydrationFluid calculation

• Water deficit Wt X of dehydration
• In mild dehydration deficit 50 ml/kg
• (1kg1000gm1000 ml 5 50ml/kg)
• In moderate dehydration deficit 60-90 ml/kg
• In severe dehydration deficit gt 100 ml/kg

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Oral rehydration therapy (ORT)

• ORT is divided into 2 phases
• A. Rehydration phase aims to restore the
  existing deficit fluid
• B. Maintenance phase compensate for continued
  fluid loss
• Golden rule
• Give them as much as they will drink

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Oral rehydration therapy

• A. Rehydration phase Replacement of existing
  deficit
• Deficit is calculated according to severity of
  dehydration
• Mild dehydration 50 ml/kg
• Moderate dehydration 70 ml/kg.
• Calculated deficit should be given over 4-6 hour
  by small and frequent feed

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Oral rehydration therapy (cont..)

• B. Maintenance phase Replacement of fluid for
  continued loss until diarrhea stops
• 1 mL of ORS should be replace for each gram of
  diarrheal stool
• Mild diarrhea ( 1 stool every 2 hours) ORS
  100 ml/kg/day until diarrhea stops
• Severe diarrhea (gt 1 stool every 2 hours) Need
  hospital supervision.
  Replace as follows
  
• If stool can not be measure- 10 ml/kg/motion
  
• in severe diarrhea- 10 ml/kg/hour
• If vomiting 2 mL/kg for each episode of vomiting
  

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Management of dehydration Parenteral therapy

• Indications
• Severe dehydration
• Persistent vomiting
• Unable to take orally
• Intestinal surgery
• Paralytic Ileus

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Parenteral therapy Shock therapy

• To be given in severe dehydration.
• Goal is to expand the intravascular fluid volume
  rapidly to save the vital organs.
• Isotonic solutions are used e.g. N. saline,
  ringer lactate, albumin, plasma
• Normal Saline 20 ml/kg IV bolus rapidly over
  20-30 minute
• Repeat bolus until patient is hemodynamically
  stable.
• This phase of therapy is same for all types of
  dehydration

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Parenteral therapy (cont..)Subsequent therapy

• Depends upon types of dehydration
• Isotonic hypotonic dehydration
• Calculated deficit should be replaced over 24
  hours
• Fluid given in initial phase is to be deducted
  from the calculated deficit
• Calculate maintenance requirement for 24 hour
• Calculate Na K deficit choose appropriate
  fluid
• Half of the deficit maintenance requirement
  should be given over 8 hours
• Remaining half to be infused over 16 hours

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Fluid electrolyte calculation

• Water deficit Wt X of dehydration
• In mild dehydration deficit 50 ml/kg
• (1kg1000gm1000 ml 5
  50ml/kg)
• In moderate dehydration deficit 60-90 ml/kg
• In severe dehydration deficit gt 100 ml/kg
• Electrolyte deficit
• Na Cl deficitwater deficit X 8 mmol/100ml
• K deficit water deficit X 3 mmol/100 ml

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Example Child wt 10 kg arrived in ER with
severe dehydration.

• Shock therapy
• 10 20200 ml of normal saline should be given
  over 20- 30 min as shock therapy
• Serum sodium was 138 mmol/l
• Subsequent therapy
• Deficit fluid101001000 ml
• Fluid given during shock therapy200 ml
• Remaining fluid deficit 1000-200800 ml
• Maintenance fluid for 24 hour101001000 ml
• Total fluid for 24 hour 800 ml1000ml 1800 ml
• One half of total fluid 900ml to be given over 8
  hour
• Other half 900ml to be infused over 16 hour

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Parenteral therapy(cont..)

• Choice of fluid
• Na requirement
• Deficit0.8 800 64 mmol
• Maintenance requirement 10 220 mmol
• Total 642084 mmol/day
• Potassium 301040 mmol/day
• One half NS in D5W 20 mmol of KCL/l will be
  appropriate solution

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Parenteral therapy(cont..)

• Subsequent therapy
• Hypernatremic dehydration S Na gt 160mmol/l
• Initial phase of shock therapy is same
• Deficit therapy should be spread over 36-84 hours
  according to the result of serum Na
• Serum Na 155-170 mmol/l- over 48 hr
• Serum Na 170-183 mmol/l over 72 hr
• Serum Na 184-196 mmol/l over 84 hr
• Goal is to decrease serum sodium 10 mmol/24hr

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Parenteral therapy(cont..)Example

• One yr. old wt 10 kg with severe dehydration in
  shock
• Shock therapy 20 10200 ml N S to be given
  over 30 min
• U Es result shows S. Na 170 mmol/l.
• Subsequent therapy
• Deficit10 1001000 ml
• Fluid given during initial phase 200 ml
• Remaining deficit 1000-200800 ml
• Maintenance requirement for 48 hr(10 100)
  22000 ml
• Total fluid 20008002800ml to be given over 48
  hr
• NS or ½ NS D5W KCL should be use

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Management of dehydrationReplacement of ongoing
losses

• Can be given parenterally or orally
• Any abnormal losses should be replace ml for ml
• Losses from the previous hours should be
  calculated and should be replaced over next same
  duration
• If stool quantity cannot be measure 10 ml/kg/
  per motion in previous 8 hours should be replaced
  over next 8 hours.
• Losses should be replaced every 1-6 hours
  depending on the rate of loss
• NG losses should be replaced 1-4 hourly,
• In diarrhea fluid should be adjusted 6-8 hourly.