FLUID AND ELECTROLYTE MANAGEMENT IN CHILDREN - PowerPoint Presentation

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FLUID AND ELECTROLYTE MANAGEMENT IN CHILDREN

BY

DR

G I McGIL UGWU

CONSULTANT PAEDIATRIC NEPHROLOGIST DELSUTH

Slide2

OUTLINE OF PRESENTATION

PRE-TEST FOR FLUID THERAPY

LEARNING

OBJECTIVE

INTRODUCTION

NORMAL BODY FLUID AND ELECTROLYTES

MAINTENANCE THERAPY

REPLACEMENT/DEFICIT

THERAPY

CONCLUSION

TAKE HOME POINTS

REFERENCES

Slide3

PRE-TEST FOR FLUID THERAPY

In the fetus and newborn,

Extracellular fluid (ECF) is smaller than Intracellular (ICF)

Postnatal diuresis causes decrease in the ICF

Both NA+ and water are predorminantly lost during postnatal diuresis

Premature babies have higher total body water/weight than term neonates.

Slide4

Concerning ECF and ICF,

By one year of age, the amount of ECF and ICF are largely equal

In adulthood, ECF constitutes 10-20% while ICF constitutes 20-25%

Females have higher ICF than males

The increase in ICF is largely due to cell growth in an individual.

Slide5

Concerning ECF and plasma,plasma is part of ICF

plasma volume is greater than ECFvolume

plasma water is about 10% of the body weight

blood volume is about 8% of the body weight

4.

Intestitial fluid

A

Is part of ECF

B

Is part of ICF

C

Constitutes about 13% of the total body

weight

D

Can be increased by acsitis and pleural

effusion

Slide6

Based on the caloric expenditure model, each calorie expended requires provision of water in the ratio of:

2ml/1cal/day at rest

1ml/1cal/day at rest

1ml/2cal/day at rest

2ml/2cal/ady at rest

Slide7

Also according to the caloric requirement, the ranges of Na+ nd K+ required is3mEq of Na+/100ml of water and 2mEqK+/100ml of water

4mEq of Na+/100ml of water and 4mEq of K+/100ml of water

1mEq of Na+/100ml of water and 1mEq of K+/100ml of water

2.5mEq of Na+/100ml of water and 2.5mEq/100ml of water

Slide8

Concerning plasma and intestitial fluid,

plasma is the same as intravascular fliud

hydrostatic pressue drives fliud int the plasma from the intestitial fluid

Oncotic pressure drives fluid from the plasma to the intestitial fluid

Oncotic pressure retains fluid in the intestitial fluid

Slide9

In the composition of the ECFand ICFNa and Cl are the predominant cation and inion in the ECF

K. Proteins and phosphates are the predominant cation and inion in the ECF

The amount of K in the ICF is about 10x that in the ECF

ICF fluid is governed by the balance of hydrostatic and oncotic pressures

Slide10

Concerning Maintenance fluidThis is the amount of fluid and electrolytes rquired required for dly excretion of waste products

There ia a wide variation in the daily intake of electrolytes and water in childen

60% of total excreted water is lost in the urine, 35% through the lungs and skin and 5% in the stool

40% is lost in the urine 35% thfough the lungs and skin and 25% in the stool

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A child of 4yrs who weighs about 16kg will require about 1.2litres of fluid/day

1.5litres of fluid/day

1.3litres of fluid/day

2litres of fluid./day

The gaols of maintenance fluid are

prevent dehydration

prevent electrolyte imbalance

prevent ketoacidosis

prevents protein degradation

Slide12

Maintenance fluid should contain glucose so as to

minimize carbohydrate metabolism

5g of glucose/100ml of fluid gives about 10Cal of energy

5g of glucose /100ml gives about 17Cal/l

5g of glucose/100ml represents about 20% of the daily calorie requrement

Slide13

Concerning maintenance fluid again

Children can be maintained on maintenance fluid for upto two weeks

10% dextrose is enough for the maintenance in the 1 day old newborn

The recommended fluid for a 6 and a ½ yr old child is 4.4% in 1/5 saline

The recommended for the 6 and a ½ old child is ½ saline in 5% dextrose

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Maintenance fluid requirement in a newborn is

60ml/kg/day on day one

followed by 10ml/day increament

followed by 20ml/day increament

followed by 30ml/day increament

Slide15

Maintenance fluid requirement in a newborn is60ml/kg/day on day one

followed by 10ml/day increament

followed by 20ml/day increament

followed by 30ml/day increament

Deficit fluid

is the fluid lost over a time

can be expressed as a % of the body weight

In GI losses, K and HCO3 are lost predominantly through diarrhoea

the most lost solute diarrhoea is Na

Slide16

In assessing dehydration in a child less than 2yrsmild dehydration = 3% body weight

Moderate dehydartion= 5% body weight

Severe dehydration = 8% body weight

mild dehydration=5% body weight

Moderate dehydration= 7% body weight

Severe dehydration= 10% body weight

deficit is replaced is replaced over 1-6hours

deficit is replaced over 12hours

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Dehydrationcan be isonatremic, hyponatremic and hypernatremic

The amount of Na given is 0.5Meq/L/Hr or 12mEq/L /day

in correcting dehydration, hypernatremic dehydration it is advisable to use Na free solutions

hypernatremic dehydration is corrected over 24hours

Slide18

In correcting shock

0.9% saline in 5% dextrose is the fluid of choice

fluid is given over 30mins-1hr

the amount of fluid is 40ml/kg

the amount given is subtracted from the calculed fluid loss and given over the remaing hours of correction

Slide19

Concerning On-going lossfluid is replaced ml for ml

about 10ml/kg/loose stool is adequate replacement fliud

the choice choice of fluid should be appropriately the maintenance fluid for the chid’s age/weight

normal can with or without K can be used

On-going loss is assessed

every 4hrs

every 8hrs

every 1hr

every 12hrs

Slide20

The following considerations should be borne in mind

hyponatremia may develop anytime during the course of therapy

the electrlytes should be checked every 24hours

in elctrolyte values are abnormal they should be checked every 8hours

a reduced urine output always indicates renal failure

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Oral rehydration therapy

is prefered for uncomplicated moderate dehydration

for mild dehydration, 50ml/kg over 4hours is adequate

90ml/kg for moderate dehydration over 4hours is adequate

both mild and moderate dehydration are foolowed with 100ml/kg/day

Slide22

Feeding must be continued while ORT is on

ORT can be used to correct severe dehydration

The current WHO packs contain less solutes than the previous packs

ORS is contraindicated in a child with vomiting

Slide23

INTRODUCTIONWater is the most plentiful constituent of the human body

Total body water varies from age to age, being highest in the youngest, with the preterm baby having the highest.

TBW is divided into ICF and ECF.

In the fetus and the newborn, ECF is larger than the ICF

The normal postnatal diuresis causes a decrease in the

ICF

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Coupled with the increse in ICF due to cell growth, by one yr of life, the ratio of ICF to ECF almost equals that in adulthood where ECF constitutes 20-25% of the body weight and ICF 30-40%, close to twice the ECF volume.

With puberty, the increased muscle mass in males makes them to have higher ICF than females

There is however no significant diff in the postpubertal ECF of males and females.

The ECF is further divided into plasma water and the intestitial water. The plasma water is 5% of the body weight and with a hematrocit of 40%, blood volume is usually 8% of the body weight. This is however higher in the newborn and infact it is 10% in

preterms

Slide25

The volume of plasma water is altered by pathological conditions such as dehydration, anaemia, plycythaemia, haert failure, abnormal plasma osmolality and hypoalbuminaemia.

The intestitial fluid, normaly 13% of body weight, can increase drmatically with edema, such as heart failure, protein losing enteropathy, liver failure, nephrotic syndrome and sepsis.

An increase in interstitial fluid also occurs in ascitis and pleural effusion

.

Slide26

There is always a delicate equilibrum betwee the intravascular fluid (plasma) and the interstitial fluid, which is governed by the hydrstatic and oncotic pressure.While the hydrostatic pressure drives fluid from the intravascular space to the interstitial fluid, oncotic pressure prevents fluid from moving from the intravascular compactment to the interstitium

The composition of the solutes in the ICF and ECF are diff.

Na and Cl are dorminant cation and anion in the ECF respectively and are much lower in the ICF

.

Slide27

K is the most abundant cation in the ICF and its ICF content is about 30% that in the ECF. Proteins, organic anions and pphosphate are the most plentifull anions in the ICFBased on the

caloric expenditure model,

each calorie expended requires provision of water in theratio of 1ml/cal metabolized/day at rest.

Also according to the caloric expenditure model, Na and K ranges/100ml of maintenance fliud is 3mEq/100ml and 2mEq/100ml

respectively.

Slide28

NORMAL ELECTROLYTES IN CHILDREN

Electrolyte

composition

The concentration of the major cations and anions in the intracellular space and the plasma, expressed in mEq/L.

Slide29

MAINTENANCE THERAPY

Can be given orally or intravenously for patients who cannot tolerate orally

This is the amount of fluid electrolytes required for the dialy metabolism and also corrects the fluid necessary for obligate excretion of wiaste products esp solutes (see above)

Usually there is a wide variation in the daily intake of water and electrolyes

.

Slide30

Only exceptions are children who receive fixed amount of fluids such as in SIADH secretion, also children who receive f;luids via N/G tube, or as intravenous total parentheral nutrition

Maintenance fluids are most commonly necessary in preoperative and postoperative surgical patients

There are however nonsurgical conditions that require maintenance fluid calculation

Most important thing is to recognize when to commence maintenance

therapy

Slide31

The goals of maintenance fluids arePrevent dehydration

Prevent

electrolyte

disorders

Prevent ketoacidosis

Prevent

protein degradation

Slide32

Maintenance are generally composed of a solution of water, glucose, Na+, K+. Other electrolytes are such as Ca2=, PO4- etcAddition of glucose of a minimum of 5gm/100ml (5%dextrose, to the fluids provides about 17kcal/100 which is about 20% of the daily requirement but is enough tominimize tissue catabolism to the point that protein stores are ‘spared’ from providing substrate for gluconeogenesis.

Ketosis from fat metabolism is also prevented.(remem our

goals)

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However patients will lose weight on this regimen. That is why patients are started on total parentheral nutrition just after a few days on maintenace fluids.

Also maintenance fluids lack essential requirements such as proteins, fat, vitamins and minerals.

The maintenance values are calculated as a guide based on the body weght of the child.

Slide34

Body weight method for calculating maintenance is as follows:Body Weigth Fluid

per

day

0-10kg

100ml/kg

11-20kg

1,

000ml + 50ml/kg each kg >10kg

>20kg

1

, 500ml + 20ml/kg for each kg >20kg

Slide35

As a guide of fluid loss from the bodyUrine accounts for 60%Insensible loss from skin and lungs accounts for 35%

Stool accounts for 5%

These are however very variable as it also depends on certain extrenous factors , such as humidity,temperature hyperventilation drugs etc

Slide36

Solution available maintenace therapy (the commecially available fluids):

Solution Composition

Normal

saline(0.9%NaCl) 153mEq

Na+/L

One-half

saline(0.45%NaCl) 77mEqNa

+/L

One-third saline (

0.33%NaCl) 57mEqNa

+/L

One-quarter

saline(0.2%NaCl) 38.5mEq

Na+/L

One-fifth

saline(0.18%NaCl) 30.8mEqNa+/L

Slide37

5gm of glucose/100ml (5% dextrose) to any of the solution provides a calorie of about 20.5Kcal/100ml.One-fifth saline normally comes with 4.3% dextrose (17.6Kcal/100ml)

Ringers lactate 130mEqNa+/L

(Also contains 4mEqK+/L, 109mEq/L Cl-, 28mEqHCO3-/L and 3mg/dl of calcium

Hartman’s solution

Slide38

Choice of fluid(1) First-Line choice for children above 20-25kg is 0.45% saline (1/2 saline) with 5%dextrose

Consider adding KCl, up to 40mmol/L once plasma concentration is known

(2) Second-Line choice

0.9% saline(normal saline) in 5% dextrose

Slide39

Children more than one month but 20-25kg( 1)1/4saline in 5% dextrose. They do best with this because of thgeir high water needs /Kg

Second-Line choice

1/5th saline in 4.3% dextrose

(3) Third-Line ½ saline ff normal saline , each in 5% dextrose saline

Slide40

Summary as follows:Weight ml/kg/24hrs ml/kg/hour10kg or less

100 4

Additionally for each kg

>

10 upto 20kg

50 2

Additional ly for each

kg

>

20kg thereafter

20 1

Maximum maintenance

2000ml

per 24hrs for

girls

2500ml

per 24hrs for boys

Slide41

Neonates ,1month and <, (choice of fluid is usually 10% dextrose. K+ is usually added on day 2 especially if feeding has commenced so as to make available K+ for the newly forming cells as it is the dorminant cation intracellularly (dose 2mEq/kg/day).

Also add Na+ from day 2 at 3mEq/L

Slide42

Choice of fluid/dayDay Amount

1

60ml/kg

2

90ml/kg

3

120ml/kg

4 and >

150ml/kg

That is 30ml/kg increament /day till

day4

Slide43

The reason for the daily increament sep in sick term babies is that the GFRonly improves as from day 3, and in preterms, respiratory outcome are likely to be worse if Na+ is added before naturesis which starts as from birth, and weight loss has started

.

Do not automatically add electrolytes on day 2; check the serum electrolytes

first.

Slide44

NOTE: Above regimen for the neonates may be altered:(i) Gestation- very premature babies have very high insensible loss and may require higher amount of fluid

Incubator humidity is very important in these babies

(ii) Clinical state-eg edema (reduce fluids or increase more slowly), dehydratiom (may require more fluids)

Perinatal asphyxia- may need to reduce

ml/kg/day

Slide45

Weight- dly weighing are required in NICU babies. Beware of increasing the fluid or consider reduction in a baby in NICU if there is weight gain in the first one week of life.

Serum sodium- the best guide to hydration in the first few days of life, especially in preterm, hypernatremia; hypernatremia indicates dehydration

Slide46

RESTRIC FLUID TO 2/3RD MAINTENANCE FOR ALL CHILDREN IF BRONCHIOLITIS/PEUMONIA/MENINGITIS/ENCEPHALITIS

Slide47

REPLACEMENT THERAPY

Broadly divided in two major parts: Correcting or replacing deficit, and replacing On- going loss

Deficit Therapy

GI tract is a potential losss of considerale amount of water and electrolytes and so lead to intravascular contraction and electrolyte imbalance.

GI losses are often associated with loss of K+ leading to hypokalemia. The stool also contains a heavy amount of HCO3-, so diarrhoea leads to metabolic

acidosis

Slide48

In the absence of vomiting, diarrhoea or NG drainage, GI losses are usually minimal, but when ever losses occur, its usually considered eccessive and increase in the water requirement is equal to the volume lost

Because GI water and electrlyte losses can be precisely measured, it is possible to use an appropriate replacement fluid.

Deficits are usually replaced within1-6hrs, depending on the rate of loss.

Diarrhoea is a common cause of fluid loss in children and lead to dehydration

The first step in caring for a child with dehydration is to acceess the degree of dehydration clinically

.

Slide49

Clinical Evaluation of Dehydration

Mild Dehydration (3-5%):

normal or increased pulse, decrease urine output, thirsty, normal physical examination.(5% for infants or<20kg and 3% for older children or >20kg

Noderate Dehydration (7-10%):

tachycardia, little or no urine output, irritable/lethargic, sunken eyes and fontanel, decreased tears, dry muccuos membranes, mild tenting of the skin, delayed capillary refill, cool and pale.

Severe Dehydration (10-15%):

rapid and weak pulse, decreased blood pressure, no urine output, very sunken eyes and fontanel, no tears, parched muccuos membranes, tenting of the skin, very delayed capillary refill, cold and mottled.

Slide50

These are however estimates and infact all physical characteristics used to describe differing degrees of dehydration are really measures of the integrity or relative degree of expansion of the extracellulr fluid space.

Water deficit can be determined by subtracting the patient’s current weight from his/her weight just before dehydration

.

Slide51

However it is usually determined as above by clinical criteria is a percentage estimate of the total amount of body weight lost as water.

The

amount of loss and so amount needed to replace can be calculated by multiplying the current weight(kg) by the estimated % dehydration yeilding a figure that represents the estimated water loss in litres. If the weight is expressed as grammes, the estimated water loss will be in ml. This formular takes into account that 1ml of water weighs 1gm

.

Slide52

Na+ is the solute most lost in diarrhoea as its the predorminant cation in the ECFThe loss may be relatively equal (isotonic), larger (hypotonic) or smaller (hypertonic), to the loss of water from the

ECF

Below is the summary of management of various types of dehydration

Slide53

SUMMARY OF FLUID AND SOLUTE CALCULATIONS (“SEGAR BOX”) FOR 1 DAY

H

2

O

Na

+

K

+

Maintenance (Daily fluid

and electrolyte requirement)

100 ml/kg-first 10

kg

1000 ml + 50 ml/kg – 10-20 kg

1500 ml + 20 ml/kg - >20kg

3 mEq/100 ml of maintenance fluids/day

1

2 mEq/100 ml of maintenance fluids/day

1

+(plus) Total Deficits

-(minus) “pure free water” deficit

if

hypernatremic

2

Total deficit (ml) = weight (gm) X % estimated dehydration

(ECF loss = 60% of H2O deficit)

(ICF loss =

40% of H2O deficit)

ECF deficit (in

liters) X 140mEq/L = “isotonic” Na

+

deficit from the ECF

ECF deficit (in

liters) X 140mEq/L = “isotonic” Na

+

deficit from the ECF

Slide54

H

2

O

Na

+

K

+

+(plus) “pure free water” deficit

(for hypernatremia only)

5

Soduim

3

– 145 x

4 ml

4

2 kg

X wt (kg) = “pure free water” deficit (ml)

(MAX = 12 mEq/L decline/day)

7

BLANK

BLANK

+(plus) Excess solute losses

(for

hyponatremia only)

BLANK

135 – Sodium

6

x 0.6 x wt (kg) = amount

of sodium (mEq) needed to raise the serum sodium to normal

(MAX = 12 mEg/L rise/day)

7

TOTAL

Slide55

Acceptable ranges for maintenance of Na+ and K+/100ml of maintenance fliuds/day is 2.5-3mEq for Na+ and 2-3mEq for K+

Research and clinical experience provide us with data that substantiate a maximum safe rate for Na+ change (either from high to normal or low to normal). That rate of change is 0.5mEq/L/hr or 12mE/L/day.

Slide56

Choice of fluidThese are actually the second line maitenance fluids. (0.9%Na+ with 5% dextrose).

The

fluids are also suitable in the following conditions

Moderate- Severe dehydration/intravascular volume depletion

Significant hyponatremia (serum Na+ <135mEq/L

Need to replace ongoing

loss

Slide57

Prei-and immediate post-operative patientsCNS infections

Head injury

Bronchiolitis

Sepsis

Salt losing states

Significant hypernatremia (serum Na+>150mEq/L)

Slide58

NOTEIf shock is present, administer 0.9%NaCl, 20ml/kg (10ml/kg in the setting of trauma), given over

30min-1hr.

Repeat if necessar and call for

help.

Remember to subtract any volume used to treat shock from total calculated for deficit replacement.

Hyponatremia may develop as complication of an fluid

regimen.

Symptomatic

hyponatremia

is a medical

emergency.

Slide59

ONGOING LOSS

This

is replaced volume for volume (ml for ml), as this occurs in your presence. It presupposes that you have been measuring amount of fluid lost and its electrlyte contents

On-going loss is reassed every

4hrs

Fluids used should ideally reflect the electrlyte composition of the fluid being lost.

0.9% NaCl is appropriate in most cases (with or without the additon of K+)

For diarrhoeal diseases, a rough estimate of replacing on going loss is 10ml/loose stool/kg

Slide60

MONITORING

Check plasma electrolytes before commencing the infusion, except prior tothe majority of elective surgery

Monitor plasma glucose if glucose-free solutions are used during surgery

Check plasma electrlyes every 24hrs whilst intravenous fluids are being administered if plasma electrlytes are abnormal, consider rechecking every 4-6hrs, but definitely if plasma Na+ <

130mE/L

Slide61

Check plasma electrlytes if clinical features suggestive of hyponatremia develop; these features include nausea, vomiting, headache, irritability, altered level of consciousness, seizures and apnea

Where possible, all children on IV fluids should be weighed prior to the commencement of therapy and weighed again each day

Document accurate fluid balance daily. Assess urine output-oliguria may be due to inadequate fluid, renal failure, obstruction or the effect of ADH.

Slide62

ORAL REHYDRATION THERAPY

Lancet describes it as the greatest revolution in medical history

Current UNICEF packs have lower Na+ content and are now orange flavoured. This i aimed at reducing possible increase of the diarrhoea due to osmotic drive into the GI lumen and more palatable to the

children

Slide63

A simplified method for determi ng how much fluid to give would be:Mild dehydration:

50ml/kg over 4hrs followed by 100ml/kg/day until the diarrhoea subsides

Moderate dehydration:

100ml/kg given over the first 4hrs followed by 100ml/kg/day until diarrhoea subsides

Remember, FEEDING MUST CONTINUE while using ORS except of course the child has very severe and persistent emesis which will infact need IV fluids

Slide64

CONCLUSION

Fluid management in children is very important and care should be taken not to cause iatrgenic problems such as hyponatremia, by giving solutions with low solutes, or not recognizing a relatively higher solute loss. One should also avoid circulatory over load. Strict imput-output chart is a sine qua non for appropriate fuild

management.

Slide65

TAKE HOME POINTS

Water is the most plentiful substance in the body

It as a per centage of body weight is higher the younger the child and also higher the earlier the gestational age

At birth, the ECF is larger than the ICF but due to postnatal diuresis and cell growth, the ECF become smaller withage so that by 1yr both ECF and ICF are equal and infact ICF is almost double the ECF is adulthood

.

Slide66

Na and Cl are the predominant cation and inion in the ECF while K and, phosphates and proteins are the dominant cation and inion in the ICF

Choice of maintenance fluid varies with age with 105 dextrose prefered for the 1day old newborn at 60ml/kg/day with a daily increament of 30mlkg/day to a maximum of 150ml/kg/day except in preterms. Electrolytes may be added from day 2

Maintenance fluid for infants (some say children <20kg) is ¼ saline in 5% dextrose thereafter ½ saline in 5% dextrose.

Slide67

Never use electrolyte free fluids in children except in the newborns to avoid cerebral edemaCaloric expenditure model says iml of water is requierd to produce 1cal/day at rest and 3mEq of Na with 2mEq of K/100ml of water/day

Always add glucose to maintenance fluid to ‘spare’ protein and also prevent ketoacidosis

Maintenance fluid should be restricted in certain conditions especially CNS pathologies because of SIADH secretion

Na is the most lost electrolyte in any fluid loss

Slide68

During GI losses, K and HCO3 are lost more from diarrhoea while Cl is lot from vomiting, leading to metabolic acidosi and alkalosis respectively

Most dehydrations are isonatremic but one should also look out for hypo- and hypernatremic dehydration

The extent of dehydration is usually calculated as a % of the body weight with higher values in infants because of their relatively higher content of water

Deficit fluid is repaced over 1-6hrs while on-going loss is assessed every 4hrs and replaced ml for ml

Slide69

Shock is treated with rapid infussion of normal salin at 20ml/kg over 30mins-1hr. This is subtracted from the calculated deficit and given over the remaing period of 3to 3 and ½ hrs (if you are correcting over 4hours ) or 5 to 5 and ½ hours (if you are correcting deficit over 6hrs)

ORT is recommended for uncomplicated mild to moderate dehydration at the replacement rate of 50ml/kg for mild dehydration and 100ml/kg for moderate dehydration each given over 4hrs and maintained with 100ml/kg/day

Slide70

Monitoring is very importantCheck plasma electrolytes before commencing infussions except in shock or prior to most elective surgeries

Monitor plasma glucose if glucose free solutions are used

Hyponatremia (esp iatrogenic) can occur anytime during the course of therapy so check electrlytes every 24hrs whilst IV fluids are given and if abnormal check every 4-6hrs, but definitely if seum Na <130mEq/L

Slide71

Check plasma electrlytes if clinical features suggestive of hyponatremia which include nausea, vomiting, headache, irritability altered consciousness, seizures and apnoeWhere possible, all childtren on IV fluids should be weighed prior to comencement of therapy and daily till therapy is over

Document accurate fluid balancedly. Assess urine output: oliguria may be due to inadequate fluid, renal failure, obstruction or the effect of ADH secretion (SIADH).

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REFERENCES

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