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Definition of Terms
Disorders of fluid and electrolyte imbalance are amongst the most common disorders encountered in unwell neonates (both term and preterm). The fluid and electrolyte requirements of the neonate are unique due to fluids shifts within the first few days and weeks of life. At birth, there is an excess of extracellular fluid which decreases over the first few days after birth; extracellular fluid and insensible water losses increase as weight and gestational age decrease. Therefore, appropriate management of fluid and electrolytes must take into consideration the birth weight, gestational age and corrected age. In addition, consideration needs to be given to the unwell term or preterm neonate as the disease pathophysiology may significantly influence fluid and electrolyte requirements.Fluid management in the preterm neonate is specific and challenging due to increases in insensible water loss, reduced renal function and low birth weight. Please refer to the Neonatologist on duty or PIPER service for specific advice.
adequate hydration, fluid and sodium balance in the neonate admitted to the
Butterfly Ward neonatal intensive care unit (NICU) or high dependency unit
fluid management of the neonate outside Butterfly ward please refer to Ward management of a neonate.
Neonate A neonate less than 28 days of age
Term A neonate born after 37 weeks of completed gestation
Preterm A neonate born before 37 weeks of completed gestation
Preterm A neonate born between 32 and 36+6 weeks of completed gestation
Very Preterm A neonate born between 28 and 31+6 weeks of completed gestation
Extremely Preterm A neonate born before 28 weeks of completed gestation
Fluid balance is a function of the distribution of water in the body, water intake and water losses. Total body water (TBW) distribution gradually changes with increasing gestational age of the foetus, from the extreme preterm with TBW constituting 90% of body weight, to the term neonate with 75% TBW. In addition to this gradual reduction with gestational age is a more abrupt reduction of TBW that occurs approximately 48 to 72 hours after birth which is closely related to the cardiopulmonary adaption.
Insensible water loss occurs via the skin and mucous membrane (two thirds) and respiratory tract (one third). An important variable influencing IWL is the maturity of neonate skin, with greater IWL in preterm babies resulting from evaporation through the immature epithelial layer.
** Refer to
for Neonatal Jaundice RCH nursing guideline
** Refer to
Humidity for Premature Neonates RCH nursing guideline
Foetal urine flow steadily increases with gestational age reaching 25 – 50 mL/hr at term and dropping to 8 – 16mL/hr (1-3mL/kg/hr) at birth reflecting the large exchange of TBW during foetal life and the abrupt change occurring with cardiopulmonary adaption after birth. In addition, glomerular filtration rates (GFR) are low in utero and remain low at birth and gradually increase in the neonatal period. With a changing GFR and variable urine concentration, all newborns undergo a diuresis in the days following birth resulting from a reduction of TBW.
Contraction of TBW accounts for early postnatal weight loss and results in a 10-15% weight loss in preterm babies and 5-10% weight loss in term babies.
Where clinically appropriate:
A number of physical signs can be used in the assessment of fluid status however they can be unreliable and therefore must be observed within the context of body weight, haemodynamic monitoring, haematocrit, serum chemistries, acid-base status and urine output.Physical assessment of hydration status includes the assessment of:
All patients receiving IV fluids for acute conditions should have both oxygen saturation and cardiorespiratory monitoring. In addition, heart rate, pulse volumes, respiratory rate and capillary refill time should be assessed at hourly intervals.
*** Monitoring may be ceased by order of the medical team in the patient receiving long term intravenous fluid with stable serum electrolytes***
In the neonatal period, a physiologic increase in haematocrit occurs due to a fluid shift away from the intravascular compartment. An increase in haematocrit also occurs as a result of dehydration due to a decrease in plasma volume.
Normal Haematocrit (Term Newborn) = 0.44 – 0.64
Normal Haematocrit (3 months) = 0.32 – 0.44
RCH Laboratory = 0.31 – 0.55
The requirement of both sodium (Na+) and potassium (K+) is 2 – 4 mmoL/kg/24 hours. A sodium (Na+) value of 135 – 145 mEq/L is indicative of appropriate total body weight and sodium balance which are important factors in maintaining hydration status in the neonate. Changes in
serum sodium concentration need to be assessed in the context of total body weight and any increase or decrease in weight.
A metabolic acidosis can be suggestive of decreased intravascular volume and hypersomolarity.
All patients with intravenous fluids require labels on 1) the fluid bag/syringe, 2) the IV line (closest to the patient), and 3) the pump.
In all circumstances, intravenous fluid bags and syringes should be labelled with a fluid label printed via EMR.
All labels, hand written or printed via EMR, require the following:
Infusions with no additives:
Infusions with additives:
As described above (Assessment – RENAL FUNCTION), neonates undergo a diuresis within the first 24hours after birth and therefore electrolyte additives are not required within the first 24 hours of life unless clinically indicated.
10% Glucose (500 mL)
+ 10 mmoL Potassium Chloride
+ 0.225% Sodium Chloride
** Refer to EMR MAR Product Instructions/Mixture Components for preparation instructions
Total parenteral nutrition (TPN) is usually commenced if the neonate is not likely to be fed for longer than 3 days. It is prescribed by the Medical Staff in conjunction with the Pharmacist and Clinical Nutrition team.
Standard solutions used in Butterfly Ward:
25g/L Amino Acids
30g/L Amino Acids
50g/L Amino Acids
Butterfly TPN Guide Card (2017)
** A ‘side arm’ of 10% Glucose +/- additives may be required on days 1 – 4 of treatment with N2 and N3 to reach an appropriate total fluid intake (TFI).
The neonatal liver normally produces 6 – 8mg/kg/min of glucose – this is the approximate basal requirement of a newborn neonate.
Glucose intake (mg/kg/min) = %
Glucose x volume (ml/kg/day)
Glucose intake (mg/kg/min) = %
Glucose x hourly rate
Weight (Kg) x 6
** Refer to
Glucose Delivery Calculator for further guidance
Gastrointestinal losses (e.g. nasogastric, ileostomy) of more than 20 mL/kg require mL for mL replacement.
Standard Replacement Fluid: 0.9% Sodium Chloride (500 mL) + 10 mmoL Potassium Chloride
Replacement of Neonatal Gastrointestinal
Losses clinical practice guidelines
In neonates with renal impairment, special consideration needs to be given to fluid management. Fluid restriction will often be required as will replacement of urinary losses in the neonate with polyuria. These patients also require a strict fluid balance
record, regular urea and electrolytes and frequent weighs (as often as twice daily).
** Refer to
Replacement of Renal Losses in NICU clinical practice guideline
10 – 20 mL/Kg of 0.9% normal saline given as rapidly as possible (may be repeated as necessary)
**Refer to Butterfly Neonatal BLS
Algorithm Learning Package for further information
evidence table for this guideline can be viewed here.
Please remember to read the
The development of this nursing guideline was coordinated by Ryan Sendall, RN Neonatal Nursing, and approved by the Nursing Clinical Effectiveness Committee. Updated October 2021.