fluids electrolytes insensible loss requirements neonates

1. FLUID AND
ELECTROLYE
REQUIREMENTS IN
NEWBORN
By :Darayus P.Gazder (DPG)

2.  The distribution of TBW between intracellular and extracellular
spaces depends on the water’s relative content of solutes
(electrolytes, proteins), that is, on its relative osmolality.
 The osmolality of intracellular and extracellular spaces, therefore, is
equal, although the composition of ICW is different from that of ECW;
sodium (Na) is the main extracellular ion, whereas potassium (K) is
the main intracellular ion.

3. In each compartment, a main solute acts to
keep water in the compartment:
 • The volume of the intracellular compartment is
maintained mainly by potassium salts and is regulated
by the Na-K cellular pump.
 • The volume of the extracellular compartment is
maintained mainly by sodium salts and is regulated by
the kidneys.
 • In the extracellular space, the volume of the
intravascular compartment is maintained mainly by the
colloidal osmotic pressure of plasma proteins.

4. Fluids and Electrolytes
 Priniciples:
 Total body water (TBW) = Intracellular fluid (ICF) +
Extracellular fluid (ECF)
 Extracellular fluid (ECF) = Intravascular fluid (in
vessels : plasma, lymph - IVF) + Interstitial fluid
(between cells - IF)
 Goals:
 Maintain appropriate ECF volume,
 Maintain appropriate ECF and ICF osmolality and
ionic concentrations

5. Things to consider:
Normal changes in TBW, ECF
 All babies are born with an excess of TBW, mainly
ECF, which needs to be removed
 Adults are 60% water (20% ECF, 40% ICF)
 Term neonates are 75% water (40% ECF, 35%
ICF) : lose 5-10 % of weight in first week ??
 Preterm neonates have more water (24 wks: 85%
TBW, 60% ECF, 25% ICF): lose 5-15% of weight in
first week
a) Placental transfusion,
b) Reabsorption of lung fluid,
c) Shift of water and electrolytes from the intracellular to the extracellular
space

6. Normal changes in Renal Function
 Neonates are not able to concentrate or dilute urine
as well as adults - at risk for dehydration or fluid
overload
 Solute concentration in urine ranges 50-800
mOsm/L in terms, 50-600 in PT
 Renal function matures with increasing:
Gestational age & Postnatal age

7. “Insensible” water loss (IWL)
 IWL  not obvious: Skin (2/3) or Resp tract
(1/3). Depends on:
 gestational age (more PT: more IWL)
 postnatal age (skin thickens with age)
 also consider losses of other fluids: Stool
(diarrhea/ostomy), NG/OG drainage, CSF
(ventricular drainage).
SWL  that seen = urine+stool

8. “Insensible” water loss (IWL)

11. MONITORING OF FLUID AND
ELECTROLYTE STATUS
 Body weight:
 Serial weight measurements can be used as a guide to estimate the fluid deficit
in newborns.
 Term neonates loose 1-3% of their birth weight daily with a cumulative loss of
5-10% in the first week of life.
 Preterm neonates loose 2-3% of their birth weight daily with a cumulative loss
of 15-20% in the first week of life
 Failure to loose weight in the first week of life should be an indicator for fluid
restriction.
 Excessive weight loss in the first 7 days or later would be non-physiological and
correction with fluid therapy.
 Clinical examination:
 Infants with 10% (100 ml/kg) dehydration may have sunken eyes and fontanel,
cold and clammy skin, poor skin turgor and oliguria.
 Infants with 15% (150ml/kg) or more dehydration would have signs of shock
(hypotension, tachycardia and weak pulses)
 Dehydration should be corrected within 24hrs.

12. SERUM BIOCHEMISTRY:
 Serum sodium and plasma osmolarity helpful in the assessment of the
hydration status in an infant.
 Serum Sodium values should be maintained between 135-145 meq/L.
 Hyponatremia with weight loss suggests sodium depletion and
would merit sodium replacement.
 Hyponatremia with weight gain suggests water excess and require
fluid restriction.
 Hypernatremia with weight loss suggests dehydration and require
fluid correction over 48 hours.
 Hypernatremia with weight gain suggests salt and water load and
would be an indication of fluid and sodium restriction.
URINE OUTPUT,SPECIFIC GRAVITY AND OSMOLARITY:
 Urine output would be 1-3ml/kg/hr
 Specific gravity between 1.005 to 1.012
 Osmolarity between 100-400 mosm/L.
 Specific gravity can be checked by dipstick or by a hand held
refractometer.

13.  Blood gas:
 Useful in the acid base management of patients with
poor tissue perfusion and shock.
 Hypo-perfusion is associated with metabolic acidosis.
 Fractional excretion of sodium (FENa):
 Indicator of normal tubular function but is of limited
value in preterm infants due to developmental tubular
immaturity
 Serum blood urea nitrogen (BUN), creatinine:
 Serum creatinine is a useful indicator of renal function.
There is an exponential fall in serum creatinine levels in
the first week of life as maternally derived creatinine is
excreted. Failure to observe this normal decline in serial
samples is a better indicator of renal failure as compared
to a single value of creatinine in the first week of life.

14. GUIDELINE FOR FLUID REQUIRMENT
Day 1 Term babies and babies with birth weight > 1500gms
 A full term infant on intravenous fluids would need to excrete a
solute load of about 15 mosm/kg/day in the urine.
 The infant would have to pass a minimum of 50 ml/kg/day.
 Allowing for an additional IWL of 20 ml/kg, the initial fluids should
be 60-70 ml/kg/day.
 The initial fluids should be 10% dextrose with no electrolytes to
maintain GFR 4-6 mg/kg/min.
 Hence total fluid therapy on day 1 would be 60 ml/kg/day.

15. Day 1: Preterm baby with birth weight 1000-1500 grams
 Urine output similar to term baby however fluid
requirement is more in preterm because of increased
IWL and increased weight loss(ECF loss).
 To reduce the IWL under warmer,there should be liberal
use of socks,cap,plastic barriers.
 80ml/kg/day of 10%dextrose is adequate on day 1.

16. Day 2 - Day 7: Term babies and babies with birth weight
>1500gm
 As infant grows and receives enteral milk feeds, the solute
load presented to the kidneys increases and the infant
requires more fluid to excrete the solute load.
 Water is also required for fecal losses and for growth
purposes.
 The fluid requirements increase by 15-20 ml/kg/day until a
maximum of 150 ml/kg/day.
 Sodium and potassium should be added after 48 h of age
and glucose infusion should be maintained at
4-6mg/kg/min

17. Day 2 – Day 7: Preterm babies with birth weight 1000-1500
grams
 As the skin matures in a preterm baby, the IWL progressively decreases
and becomes similar to a term baby by the end of the first week.
Hence,the fluid requirement would become similar to a term baby by the
end of first week.
 Plastic barriers, caps and socks are used throughout the first
week in order to reduce IWL from the immature skin.
 Fluids need to be increased at 10-15 ml/kg/day until a maximum of 150
ml/kg/day.
>Day 7: Term babies and babies with birth weight >1500 grams
Fluid should be given at 150-160 ml/kg/day.
>Day 7: Preterm babies with birth weight 1000-1500 grams
Fluids should be given at 150-160 ml/kg/day and sodium
supplementation at 3-5 mEq/kg should continue till 32-34
weeks corrected gestational age.

18. 05/10/17
Fluid Requirement
Birth wt (gm) Day 1 Day 2 Day 3-6 Day >7
<750gm 100-140 120-160 140-200 140-160
750-100gm 100-120 100-140 130-180 140-160
1000-1500gm 80-100 100-120 120-160 150
>1500gm 60-80 80-120 120-160 150

19. Additional allowances
 These are applicable more for very preterm
baby due to increased IWL
 Radiant warmer -20 ml/kg/day
 Phototherapy -20 ml/kg/day
 Increased body temperature -10-20 ml/kg/day

20. HYPONATREMIA
The most frequent electrolyte disorder
S . Na+ < 135 meq/L
• Most common cause - administration of hypotonic fluids
• Others - Pituitary or adrenal insufficiency, brain injuries, brain
tumours, stress ,pain, nausea and vomiting are all potent causes of
ADH release.
The early signs - non-specific
• The first presenting feature is a seizure or respiratory
arrest.(s.sodium <125 meq/L)
Management
• Medical emergency and transfer to PICU.
• Hyponatraemic seizures - respond poorly to anticonvulsants
• Initial management is to give an infusion of 3% NaCl Sol.
• One ml/kg of 3% sodium chloride will normally raise the
serum sodium by 1mmol/l.

21. Amount of Na+/mL (from Table A) × Total fluids/d =
Amount of Na+/d