PEDIATRIC FLUIDS

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PEDIATRIC FLUIDS
Katinka Kersten, MD
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ECF and ICF

• Body has two fluid compartments
• Extracellular fluid (ECF) space makes up 1/3 of
  our body fluids
• Intracellular fluid (ICF) space makes up 2/3 of
  our body fluids
• Extracellular space refers to fluids outside our
  cells which may be interstitial fluid or plasma
• Total body water 0.6 X weight (kg) for children
  and adults and 0.78 X weight (kg) for neonates
  and infants

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Approach to Fluid Calculations

• 1. Maintenance Determined by a system
• a. Caloric expenditure method
• b. Holliday-Segar method c.
  Surface area method
• 2. Deficit Determined by acute weight
  change or clinical estimate
• 3. Ongoing losses Determined by measuring

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Maintenance Fluids
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Caloric Expenditure Method

• Based on understanding that water and electrolyte
  requirements parallel caloric expenditure but not
  body weight
• Is effective for all ages, shapes, and clinical
  states, many age based tables exist for
  estimating caloric needs
• Per 100 calories metabolized you need 100-120 ml
  H2O, 2-4 mEq Na, and 2-3 mEq K

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Holliday-Segar Method

• Quick, simple formula that estimates caloric
  expenditure from weight alone
• Assumes that for each 100 calories metabolized,
  100 ml H2O will be required (50 ml/100 calories
  for insensible loss, 67 ml/100 calories for urine
  and 17 ml/100 calories gained from metabolism)
• Not suitable for neonates lt 14 days old

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Holliday-Segar cont.
WEIGHT (kg) FLUIDS 0 - 10 100
ml/kg/day 11 20 1000 ml 50 ml/kg for
each kg above 10 gt20 1500 ml 20
ml/kg for each kg above 20
Electrolyte needs per 100 ml Na 3 mEq Cl-
2 mEq K 2 mEq
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Body Surface Area Method

• For non-dehydrated patients
• Water 1500 ml/M2/24 hr
• Sodium 30-50 mEq/M2/24 hr
• Potassium 20-40 mEq/M2/24 hr
• Mild dehydration
• Water 2000 ml/ M2/24 hr
• Moderate dehydration
• Water 2500 ml/ M2/24 hr

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Examples

• A 6 kg child needs 600 ml/day, which equals 25
  ml/hr
• A 35 kg child needs 1800 ml/day,which equals 75
  ml/hr
• A 14 kg child needs 1200 ml fluids with
• Na 36 mEq (3 mEq/100 cal)
• K 24 mEq (2 mEq/100 cal)
• Cl 48 mEq (4 mEq/100 cal)

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Modifications
Increase Decrease Fever (12 for each oC
Renal failure above 37 oC ) Heart
failure High ambient temperature Inappropriate
secretion Diabetes mellitus of ADH Diabetes
insipidus High-humidity respiratory Vigorous
exercise therapy
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Acute Renal Failure

• Meticulous management of fluids and electrolytes
  is required, including twice daily weights,
  strict I/Os and close laboratory monitoring
• Oligo-anuric patients should receive fluid intake
  equal to their total output output must include
  insensible losses
• Insensible losses should be replaced with D5W (or
  D10W)

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Neonates

• Insensible losses in neonates vary with
  gestational age and birth weight and may be
  dramatically increased by phototherapy or radiant
  warmers
• Newborns cannot concentrate urine as well and GFR
  is lower so they are more prone to fluid overload

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Deficit Therapy
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Clinical Observations
Examination 3-5 (mild) 10 (moderate) gt10
(severe) Skin turgor Normal Tenting
None Skin-touch Normal Dry Clammy Buccal
mucosa/lips Moist Dry Parched Eyes Norm
al Deep set Sunken Crying/tears Present Re
duced None Fontanelle Flat Soft
Sunken CNS Consolable Irritable
Lethargic Pulse Regular Slight increase
Increased Urine output Normal Decreased
Anuric
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Tenting
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ECF and ICF Composition
ICF (mEq/L) ECF (mEq/L) Sodium 20
135-145 Potassium 150 3-5
Chloride --- 98-110 Bicarbonate 10 20-25 Pho
sphate 110-115 5 Protein 75 10
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Electrolytes in Body Fluids (mEq/L)
Na K Cl HCO3 Gastric juice 20-80
15 125 0 Small-intestinal juice 100-140
15 155 40 Diarrhea 10-90 40 40
40 Sweat normal 10-30 10 25 0 Sweat
CF 50-130 15 75 0
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ECF and ICF Percentage of Loss
fluid of deficit fluid of
deficit Duration of illness from ECF
from ICF lt3 days 80 20 gt3days 60
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Laboratory Tests that can Help

• Urine specific gravity
• Urine electrolytes
• Fractional excretion of Na (UNa/PNa)/(UCr/PCr)
• Serum electrolytes
• Serum osmolality
• 2(Na) BUN/2.8 glucose/18
• Renal function

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Isonatremic Dehydration

• Patient is dehydrated and Na is 135-145 mEq/L
• Determine fluid deficit as percentage of weight
  based on clinical findings
• Determine which parts of deficit come from ICF
  versus ECF compartments based on duration of
  illness
• ECF Na loss Fluid deficit (L) X from ECF X
  145
• ICF K loss Fluid deficit (L) X from ICF X 150

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Hyponatremic Dehydration

• Na is lt 135 mEq/L
• Follow same steps as for isonatremic dehydration
• Additional Na requirement
• (CD CP) X fD x wt
• -CD is concentration desired
• -CP is concentration present
• -fD is distrubution factor as fraction of body
  weight (L/kg)
• 0.6-0.7 for Na

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Hyponatremic Dehydration cont.

• Frequently seen in children with vomiting and
  diarrhea who have received tap water as an oral
  replacement
• Shock is an early symptom
• Physical exam findings usually exaggerate amount
  of dehydration
• Correcting Na to quickly in adults can lead to
  central pontine myelinosis this has not been
  described in children

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Hypernatremic Dehydration

• Before you start any fluid and electrolyte
  calculations you need to determine free water
  (FW) amount
• (Na)actual (Na)desired
• (Na) actual
• Based on above formula for Na lt 170 mEq/L
  approximately 4 ml of FW needed to bring Na down
  by 1 mEq/L/kg for Na gt 170 mEq/L approximately
  3 ml of FW needed to bring Na down by 1 mEq/L/kg
• Subtract FW from total fluid deficit and replace
  remainder in same way as done for isonatremic
  dehydration

x 100 ml/L x 0.6L/kg of body weight ml/kg FW
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Hypernatremic Dehydration cont.

• Mortality can be high
• Often iatrogenic
• The circulating volume is preserved at the
  expense of the
• intracellular volume and circulatory disturbance
  is delayed
• The patient looks better than you would expect
  based on
• fluid loss
• Always assume total fluid deficit of at least 10
• You only want to correct half of the fee water
  deficit in first 24 hours if Na lt 175 mEq/L
• For Na gt 175 mEq/L you do not want to correct
  faster than 1 mEq/L/hr because of risk of
  cerebral edema

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Electrolytes in Popular Drinks
Na (mEq/L) K (mEq/L) Apple juice 0.4 26 Coke 4
.3 0.1 Gatorade 21 2.5 Milk 22 36 OJ 0.2 49
Pedialyte 45 20 WHO ORS 90 20
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Composition of Parenteral Fluids
Fluid cal/L Na K CL HCO3 mEq/l D5W 170 D10W
340 NS 154 154 1/2 NS 77 77 D5 1/4
NS 170 34 34 LR 130 4 109 28 Alb.
25 1000 100-160 lt120
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Clinical Dehydration Scenarios
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Isonatremic Dehydration
A 2 year old has a 4-day history of
gastroenteritis, poor fluid intake and infrequent
urination. On exam you find dryness of the
mucous membranes, sunken eyes with mild tenting
of the skin. The serum sodium is 137 mEq/L. The
weight is 10 kg. You determine the child is
suffering from about 10 dehydration. What are
the fluid and electrolyte requirements?
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Isonatremic Dehydration
H2O Na K Cl (ml) (mEq) (mEq)
(mEq) Maintenance Total deficit 1000 ml
Extracellular fluid deficit (60 of
total) Intracellular fluid deficit (40 of
total) Total
1000 30 20 40
600 87 - 60
400 - 60 -
2000 117 80 100
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Hyponatremic Dehydration
You see a 3 year old who has had diarrhea and
been vomiting for 3 days. She has been drinking
tap water most of this time. Examination shows
sunken eyes and marked tenting of the skin but
the child is not in shock. The serum Na is 120
mEq/L. The weight 14 kg. You estimate the
deficit as 7. What are the fluid and
electrolyte requirements for this patient?
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Hyponatremic Dehydration
H2O Na K Cl (ml) (mEq) (mEq) (mEq) Maint
enance Deficit (7 of 14 kg) Extracellular
fluid (60) Intracellular fluid
(40) Additional sodium (135-120) x 0.6 x
14 Additional chloride (135-120) x 0.4 x
14 Total
1200 36 24 48
600 87 - 60
400 - 60 -
- 126 - -
- - - 84
2200 249 84 192
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Hypernatremic Dehydration
You see a 6 month old suffering for 4 days
from severe diarrhea. The mucous membranes are
dry, skin feels doughy and the child is somnolent
and lethargic. The serum Na is 165 mEq/L. The
child weighs 5 kg and you assume the fluid
deficit is at least 10. What are the fluid and
electrolyte requirements?
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Hypernatremic Dehydration
H2O Na K Cl (ml) (mEq) (mEq) (mEq) Mainten
ance Total deficit 500 ml Free water
deficit (165-145)x1/2x4x5 Remainder of
deficit (500-200) 300 ml Extracellular
(60) Intracellular (40) Total
500 15 10 20
200 - - -
180 26 - 18
120 - 18 -
1000 42 29 38
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Phase Approach

• PHASE 1
• Emergency restoration of circulation if patient
  is hypovolemic
• 10-20 ml/kg of isotonic fluids only
• PHASE 2
• Replacement of ½ of the fluid loss (deficit and
  maintenance) in first 8 hours
• PHASE 3
• Replacement of remaining ½ of the fluid loss
  (maintenance and remaining deficit) in next 16
  hours
• Replacement of potassium after voids

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Nursing Orders

• Write the type of basic fluid
• D51/2 NS most commonly used on pediatric wards
  (premixed bags are present)
• Can create any fluid you desire but may take
  longer to get if not premixed available
• Add other electrolytes as desired to the basic
  fluid
• Most commonly KCL added at 20 mEq/L but may need
  more to replace deficit
• Often only added after first void in dehydrated
  patients
• Write how fast you want it to run in ml/hr
• For example for 15 kg non-dehydrated child write
  D51/2NS 20 mEq/L of KCL to run at 50 ml/hr

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Patient Rounds

• Report total 24 hr intake
• Report what part of total intake was oral v.s.
  intravenous v.s. G-tube
• Subsequently report intake as ml/kg/day for
  children with weight lt 10 kg
• Intake for children with weight gt 10 kg should be
  reported as of maintenance
• For example a 25 kg afebrile child had a total
  intake of 2000 ml for the past 24 hr, 1600 ml was
  from iv fluids and 400 ml was po, this represents
  125 of maintenance need for this child

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Patient Rounds cont.

• Report total 24 hr output
• Report where this output came from (urine, vomit,
  diarrhea, chest tube, stoma etc)
• For the urinary output report this in ml/kg/hr as
  well