Fluid & Electrolyte TherapyFluid & Electrolyte Therapy

• C.S.N.VittalC.S.N.Vittal• 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/LEquivalent 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 CompartmentsPlasma 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)

Hypothelamus

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++

H2OH2O

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 DehydrationFrom 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 AmountWater (boiled & cooled) 2 litresWHO-ORS One 1 litre-packetSugar 50 gElectrolyte/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

ORT to prevent Dehydration – Plan A

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

ORT to prevent Dehydration – Plan A

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

ORT to prevent Dehydration – Plan A3. 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 Bfor Patients with physical signs of Dehydrationa) 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 Rehydration1. 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

Concept of Maintenance Fluids

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

Concept of Maintenance Fluids

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 2.4Less Metabolic Water 10 – 15

110 - 115

Loss per 100 Cal. of metabolism per Day

Concept of Maintenance Fluids Calculation based on caloric expenditure [ 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).

Concept of Maintenance Fluids 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)

Concept of Maintenance FluidsComposition 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 3020

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 lossesAverage 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.

- Vittal- Vittal