Fluid therapy

Fluid & Electrolyte TherapyFluid & Electrolyte Therapy
• C.S.N.VittalC.S.N.Vittal

Components of
Body Water
 ECF
 Intravascular fluid: within blood vessels (5%)
 Interstitial fluid: between cells - blood vessels (15%)
 Transcellular fluid: cerebrospinal, pericardial,
synovial
 ICF
 Inside cell
 Most of body fluid here - 40% weight
 Decreased in elderly

Body Fluid Composition
Electrolyte :
…is a substance capable of conducting
electric current in solution.
They exist in ions
> Cations : Na+
, K+
, Ca++
etc.
> Anions : Cl-
, HCO3
-
Conc. of electrolytes – expressed in mEq/L
Equivalent weight: wt. of the substance in grams that can combine with or
displace 1 gram of hydrogen.
= atomic weight / valance
For monovalent ions, 1 equivalent = 1 mole
For divalent ions, 1 Eq = 0.5 mol
For trivalent ions, 1 Eq = 0.333 mol

Body Fluid Composition
Osmolality :
…is a count of the total number of osmotically
active particles in a solution and is equal to the
sum of the molalities of all the solutes present
in that solution.
Normal = 290 mOsm/Kg
Molarity is the number of particles of a particular
substance in a volume of fluid (mmol / L)
&
Molality is the number of particles disolved in a mass
weight of fluid (mmol / kg)

ELECTROLYTE BALANCE
 The exchange of interstitial and
intracellular fluid is controlled mainly by the
presence of the electrolytes sodium and
potassium
NaNa++
KK++
NaNa++
KK++
NaNa++
KK++
NaNa++
KK++

Body Fluid Compartments
Plasma Interstitial Fluid Intracellular Fluid
Na+
142
K+
5
Ca++ 5
Mg++ 3
HCO3
–
24
Cl –
105
Protein
15
SO4 – 4
R –
2
HPO4 –
5
Na+
144
K+
5
Ca++ 5
Mg++ 3
HCO3
–
27
Cl –
118
SO4 – 4
R –
2
HPO4 –
5
Na+
6
K+
154
Mg++ 3
HCO3
–
24
Protein
15
R –
4
HPO4 –
106
SO4 – 17

ELECTROLYTE BALANCE
 Potassium is the chief intracellular cation
and sodium the chief extracellular cation
 Because the osmotic pressure of the
interstitial space and the ICF are generally
equal, water typically does not enter or
leave the cell
KK++
NaNa++

Water is …
 At Birth
 75% of body wt.
 By 2 years
 60 % of body wt.
 40% ICF
 20% ECF
 5% Intravascular (plasma)
 15% Interstitial
 Adult
 55% - Males
 51% - Females

Regulation of Body Water & Electrolytes
 For every 100 Cal metabolized, body ..
Loses Gains
 65 ml water in urine
 40 ml by sweating
 15 ml from lungs
 5 ml in feces
 15 ml from metabolism
Net loss of water = 110 ml per 100 Cal metabolized

Fluid Loss
 Absolute deficit of ECF
 Diarrhoea
 Vomiting
 Polyuria
 Decreased intake
 Decrease in effective circulation
 Nephrotic syndrome
 Cirrhosis of liver
 Portal hypertension

Fluid Regulation
 Antidiuretic hormone
 Aldosterone (Renin – Angiotensin)
 Atrial natruretic peptide
 Thirst mechanism
 Hypothalamus

Fluid Regulation
ANP
ADH Aldosterone
(Renin
– AT)
Hypo
thelamus
Thirst
KK++
NaNa++

ELECTROLYTE BALANCE
 A change in the concentration of either
electrolyte will cause water to move into or
out of the cell via osmosis
 A drop in potassium will cause fluid to
leave the cell whilst a drop in sodium will
cause fluid to enter the cell
KK++
H2O
H2O
H2O
H2O
H2O
H2O
H2O H2O
KK++
KK++
KK++
NaNa++
NaNa++
NaNa++
NaNa++

Why Infants are more vulnerable to water loss
 Physiological inability of
their renal tubules to
concentrate
 Higher metabolic rate
 Larger body surface
area
 Poorly developed thirst
mechanism
 Larger turnover water
exchange
(50% of ECF every day)

Dehydration
 Water isn’t replaced in body
 Fluid shifts from cells to EC space
 Cells lose water
 Happens in confused, comatose, bedridden
persons along with infants & elderly

Degrees of Dehydration
 Mild 3 – 5 %
 Moderate 7 – 10 %
 Severe 10 – 15 %

Symptoms of Dehydration
 Restlessness
 Excessive Thirst
 Oliguria
 Fever ±
Mild:

Signs of Dehydration
 Tachycardia
 Oliguria
 Irritable / lethargic
 Sunken eyes and fontanel
 Decreased tears
 Dry mucus membranes
 Mile tenting of skin
 Delay in CFT
 Cool & pale
Moderate:

Signs of Dehydration
 Rapid & weak pulse
 Decreased BP
 No urine output
 Very sunken eyes &
fontanel
 No tears
 Tenting of skin
 CFT – very delayed
 Cold & mottled skin
 Parched mucus
membranes
Severe:

Degrees of Dehydration
From treatment point of view, dehydration is
usually classified as :
 No dehydration,
 Some dehydration and
 Severe dehydration.
Some Dehydration
When symptoms and/or signs of dehydration are present.
Severe Dehydration
In the presence of shock and lethargy it is referred to as severe
IMNCI System

Diarrhoea Treatment Instructions

Oral Rehydration Therapy
 ORT is the cheap, simple and effective way to treat
dehydration caused by diarrhoea.
 Many of the millions of children who die every year
in developing countries from diarrhoea could be
saved if they were given ORT promptly.
 This includes giving extra fluids at home such as
tea, soups, rice water and fruit juices to prevent
dehydration, and the use of Oral Rehydration salts
(ORS) solutions to treat dehydration

Physiologic Basis For ORS
 Sodium passes into these outermost cells by
co-transport facilitated diffusion via the SGLT1
protein.
 The co-transport of sodium into the epithelial
cells via the SGLT1 protein requires glucose.
 Two sodium ions and one molecule of
glucose/galactose are transported together
across the cell membrane through the SGLT1
protein.

WHO ORS Formulae - comparison
Standard ORS
(g/L) --- (mEq/L)
Reduced osmolarity
ORS (2003)
Sodium
Chloride
2.6 90 75
Chloride 80 65
Potassium
chloride
1.5 20 20
Trisodium
Citrate
2.9 10 10
Anhydrous
Glucose
13.5 111 75
Total
Osmolarity 311 245
(All values in mmol / litre)

Advantages of Low Osmolar ORS
• Reduces stool output by about 25% when
compared to the standard WHO ORS.
• Reduces vomiting by almost 30%
• Reduces the need for IV therapy by > 30%.
• Results in reduced hospitalization

Super ORS
… are the special types of ORS which instead of mono-sugars
contain more complex sugars. They may be Food- based ( as
rice-based ) or otherwise be starch-free (Glycine / alanine based
or Glucose polymer based
Advantages of Super-ORS
 Provides rehydration.
 Helps in reducing the stool output, frequency of stools and
duration of diarrhea.
 Furnishes increased amount of calories (180 kcal/ litre)
 Contributes to weight gain, as it provides additional nutrition (thus
is especially useful for those who are malnourished).
 With gradual release of glucose, prevents secondary disaccharide
intolerance.
Disadvantages
 Short shelf-life (not exceeding 10 hours)

Resomal
 An oral rehydration salt (ORS) adapted to the needs of
the severely malnourished patients.
Ingredient Amount
Water (boiled & cooled) 2 litres
WHO-ORS One 1 litre-packet
Sugar 50 g
Electrolyte/mineral solution 40 ml
(K, Mg and Zn)
ReSoMal contains approximately 45 mmol Na, 40 mmol K
and 3 mmol Mg/litre
ReSoMal solution must only be given orally in small sips / by NG tube.

Management of Diarrhoea
Plan A: Treat Diarrhoea at Home
Plan B: Treat Some Dehydration with ORS
Plan C: Treat Severe Dehydration Quickly

ORT to prevent Dehydration – Plan A
Counsel the mother 4 rules of Home Treatment
1. Give Extra fluid (as much as the child takes)
2. Give Zinc supplements
3. Continue Feeding
4. When to Return

1. Give Extra fluid (as much as the child takes)
1. Tell mother to breast feed, give ORS, food based fluids
(soup, rice water, yoghurt drinks), or clean water
2. Teach mother how to mix and give ORS
3. Show how much extra fluid to give in addition to usual
fluid intake
1. Upto 2 yrs : 50 – 100 ml after each loose stool
2. 2 yrs or more : 100 – 200 ml

2. Give Zinc Supplements
1. Tell mother how much zinc to give
1. Up to 6 mo : ½ tab per day for 14 days
2. 6 mo and > : 1 tab per day for 14 days
2. Show mother how to give zinc supplements
3. Remind mother to give zinc for full 14 days

3. Continue Feeding
4. When to Return
1. Immediately :
1. Child is not able to drink or breastfeed
2. Child becomes sicker
3. if blood per stool or
4. drinking poorly
2. After 5 days : if diarrhoea persists

Prevention of dehydration – Plan A
Age Amt of ORS after
each stool
< 24mo 50 - 100ml
2yr -10yr 100 - 200ml
> 10yrs As much as wanted
How much ORS ?

ORT to prevent Dehydration – Plan B
for Patients with physical signs of Dehydration
a) Correction of existing water and electrolyte
deficit as indicated by the presence of signs of
dehydration
b) Replacement of ongoing losses due to
continuing diarrhoea to prevent recurrence of
dehydration
c) Provision of normal daily fluid requirement

Weight Wt 6 kg 6 – 10 kg 10 – 12 lg 12 – 19 kg
Use child’s age only when you do not know the weight.
Approx amt of ORS required (ml) = Child’s Wt. in Kg. X 75

SOME DEHYDRATION: PLAN B
 ORS: 75ml/kg plus
for ongoing losses
(50ml/stool)
 one liter of potable
water + one full
sachet of ORS to be
dissolved & kept in a
container with lid.

When is ORT ineffective ?
 High stool purge rate ( > 5 ml/kg/hr)
 Persistent vomitings ( > 3 / hr)
 Incorrect preparation of ORS
 Abdominal distension
 Glucose malabsorption

Children with Severe Dehydration – Plan C
 Start IV fluids immediately
 While drip is being set up give ORS
of child can drink

Parenteral Fluid Therapy
1. Deficit
2. Maintenance
3. Ongoing losses replacement

Principles Of Rehydration
1. Step I
• Restore intravascular volume
• Normal saline (20ml/kg) over 20 minutes
(Repeat until intravascular volume restored)
2. Step II
• Calculate 24 hour water needs (maintenance &
deficit)
• Calculate 24 hour electrolyte needs
• Both maintenance & Deficit sodium and potassium
• Subtract the fluid volume/ electrolyte concentration
used in resuscitation phase.
3. Step III
• Replace ongoing losses

Electrolyte Deficit
 Rapid Dehydration (< 2 days)
 Ratio of ECF to ICF deficit is 75 : 25 %
 Moderately Rapid Dehydration (2-7 days)
 Ratio of ECF / ICF is 60 : 40 %
 Slow Dehydration (>7days)
 Ratio of ECF / ICF is 50 : 50 %

Classification of Dehydration based on Tonicity
 Isonatremic (Isotonic) Dehydration
 Serum Na =135 to 145 mEq./L
 Hyponatremic (Hypotonic) Dehydration
 Serum Na < 130 mEq./L
 Hypernatremic (Hypertonic) Dehydration
 Serum Na >145 mEq./L

Concept of Maintenance Fluids
Principles of Therapy -2. MAINTENANCE
Calculation based on caloric expenditure

[ Holiday & Segar Formula ]
Wt. Calories Expended Maintenance waterWt. Calories Expended Maintenance water
Till 10 Kg 100 Cal / Kg 100 ml / Kg
10 – 20 Kg 1000 Cal + 50 Cal for 1000 ml + 50 ml for
Every Kg > 10 / Kg Every Kg >10 / Kg
20 Kg 1500 Cal + 20 Cal for 1500 ml + 20 ml for
every Kg above 20 Kg every Kg above 20 Kg

Route Water Na K
Evaporative
 Lungs
 Skin
15
40
0
0.1
0
0.2
Stool 5 0.1 0.2
Urine 65 3.0 2.0
TOTAL 125 3.2 2.4
Less Metabolic Water 10 – 15
110 - 115
Loss per 100 Cal. of metabolism per Day

[ Holiday & Segar Formula ]
Wt Water (ml /day) Water
ml / hr
Electrolytes
mEq / L of water
0 – 10 kg 100 ml / kg 4 / kg Na 30, K 20
10 – 20 kg 1000 + 50 ml /kg for
each kg above 10
40 + 2 / kg
for each kg
above 10
Na 30, K 20
> 20 kg 1500 + 20 ml /kg for
each kg above 20
60 + 1 / kg
for each kg
above 10
Na 30, K 20
Baseline estimates are affected by fever (increasing by 12% for each degree
> 37.8° C), hypothermia, and activity (eg, increased for hyperthyroidism or
status epilepticus, decreased for coma).

Example : 22 kg child
For the first 10 kg: 10 X 100 = 1000 ml
For the second 10 kg 10 X 50 = 500 ml
For every kg > 20 2 X 20 = 40 ml
TOTAL = 1540 ml / 24 hrs
i.e. = 64 ml / hr maintenance fluid

Concept of Maintenance Electrolytes
 Insensible water losses contain no electrolytes
 Na+
and K+
losses are those present in urine,
feces and sweat.
•3 mEq of Na in 100 ml of fluid
•2 mEq of K in 100 ml of fluid

Maintenance Fluid and Glucose
Maintenance fluid must contain glucose –
 To prevent hypoglycemia
 To prevent catabolism by providing calories
• If 20 % of caloric requirement is met, tissue catabolism
can be avoided
• 5 g of glucose (provide 20 Cal. Is added to 100 ml of
maintenance fluid)

Composition
 Differs from solutions used to replace deficits
and ongoing losses.
 Patients require
 Na 3 mEq/100 kcal/24 h (3 mEq/100 mL/24 h)
and
 K 2 mEq/100 kcal/24 h (2 mEq/100 mL/24 h).
 This need is met by using 0.2% to 0.3%
saline with 20 mEq / L of K in a 5% dextrose
solution.
 Other electrolytes (eg, Mg, Ca) are not
routinely added.

Maintenance Fluid and Glucose
Maintenance fluid Choice –
< 1 yr : 0.2% NaCl, 5% D/W plus 2 mEq KCl / 100 ml
> 1 yr : 0.33% NaCl, 5% D/W plus 2 mEq KCl / 100 ml
> 3 yr : 0.45% NaCl, 5% D/W plus 2 mEq KCl / 100 ml
 Rate : at 64 ml / hr

Calculating Deficit, Maintenance and
Total Electrolytes
 Moderately Rapid (2-7 days)
 Therefore ECF / ICF Ration is 60 / 40 %
 Deficit Water is 1000 ml
 ECF Component is 60% (600 ml) and
 ICF component is 40% (400 ml)
 Principle electrolyte in ECF is Na which is 140 mEq/L
For 600 ml = 84 mEq.
 Principle electrolyte in ICF is K which is 150 mEq/L
For 400 ml = 60 mEq.

Calculating Deficit, Maintenance and
Total Electrolytes
 Maintenance / d 1000 30 20
 ECF Water Deficit 600 84 -
 ICF Water Deficit 400 - 60
 Total 2000 114 80
H2O Na K
ml mEq mEq

Na+
K
+
Cl
-
Bicarb++ Ca
++
G/100 ml mOsml/L
D5-W 5 252
D10-W 10 505
Normal Saline (0.9%) 154 154 308
0.45% Na Chloride 77 77 154
0.45% Na Cl + 5% Dex 77 77 5 400
0.33% Na Cl + 5% Dex 56 56 5 350
D5-Normal Saline 154 154 560
D5-0 45% Na Chloride 77 77 406
D5-0.2% Na Chloride 34 34 321
D5-Ringer's Lactate 130 4 109 28 2.7 525
Ringer's Lactate 130 4 109 28 2.7 273
3% Na Chloride 513 513 1027
Ready Mixed Solutions (Electrolyte Content is meq per Liter)

Fluid Therapy
 Phase 1 : (Shock Therapy)
 Restoration of volume - 1 to 2 hrs
20 ml / Kg N.Saline or R.L. rapid IV

Fluid Therapy
 Phase 2 :
 Replacement of ½ the calculated fluid loss
(Deficit + Maintenance) in first 8 hrs.

Fluid Therapy
 Phase 3 :
 Replacement of ½ the calculated fluid loss
(Deficit + Maintenance) in next 16 hrs
 Replacement of K+
(after voiding with a max. of 40mEq/L)
 Half the potassium deficit is replaced in 1st
day

Calculating pre-illness weight:
Eg. Infant with moderate isonatremic dehydration –
weighing now 5.3 kg
 Pre illness weight is say ‘X’
 X / 5.3 = 100 / 90
 X = 530 / 90 = 5.9 kg.
Deficit is (10 % Dehydration) = 600 ml.
Maintenance fluid = 600 ml (Holideay& Segar)

Eg. 10 Kg child
 Phase 1 (1st
hr)
 20 ml / Kg of NS
(200 ml of NS, 31 mEq. of Na)
 Phase 2 (2-8 hrs)
 Replace half the fluid loss in next 7 hrs
 900 ml in 7 hrs That is 129 ml / hr
 We like to add Na in a conc of 46 mEq. L
(which is roughly in 1/3rd
NS
 We can use 1/3 NS in 5% D/W at 129 ml / hr.
 Phase 3 (hrs. 9-24) [ patient voids ]
 Replace remaining half of fluid loss and add K now
 900 ml over 16 hrs of D5, 1/3 NS at 56ml/hr
 (Pt has 25mEq/L of K loss. We are replacing 900 ml (roughly 1 L) of
fluid we may chose 25mEq./L of KCl

Treating Hypotonic Dehydration
(S. Na+ < 130 mEq/L)
 First calculate the total fluids and electrolytes needed for
isonatremic dehydration plus maintenance fluids.
 Then use the following formula to raise the serum sodium:
Wt (kg) x 0.6 x desired mEq increase in serum Na+
 After correction of shock, prefer ½ N DNS rather than 1/3 N DNS
 If child is convulsing : 3ml/Kg of 3% Nacl over 10-15 min
 Raising the S.Na by 5 mEq/L is sufficient to control symptoms.

Treating Hypertonic Dehydration
(S. Na+ > 150 mEq/L)
 This type of dehydration is usually the most serious and
correction should be done with caution. Rapid correction
 May result in CNS problems.
 Generally, elevated serum sodium should be lowered no faster
than 15 mEq/L in 24 hours.
 One simple way is to calculate the total maintenance and deficit
fluid and electrolytes that would be used in isotonic dehydration
but keep sodium at maintenance levels.
 Give deficit fluid over 48 hrs rater than 24 hrs
 Hydrating fluid must contain Na +

Treating Potassium Deficits
 Regardless of the deficit, the usual maximum
 concentration of K+ is 4 mEq per 100 ml of IV
fluid (for peripheral infusion).
 For most instances 2-3mEq per 100 ml will
suffice.
 In cases of hypokalemia higher levels can be
used, but the heart should be monitored.
 Before giving potassium be aware of the
possible existence of renal failure.

Replacement of ongoing losses
Average composition of diarrhoeal stools
 Na+ 55 meq/l
 K+ 25 meq/l
 HCO3 15 meq/l
 Fluid for replacement (ml/ml every 1-6
hourly)
 D 5 with 1/4 NS + 15 meq /l bicarbonate +
25 meq/l of KCL.

Priniciples of Rehydration - Summary
 Select an appropriate fluid (based on total
water and electrolyte needs)
 Administer half the calculated fluid during
the first 8 hours
 Administer the remainder over the next 16
hours
 Don’t add KCL until the child voids urine.

Fluid therapy

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