Introduction

Patients admitted to the Butterfly ward (Neonatal Intensive Care Unit) are at times unable to receive the required volume of enteral feeds to promote and sustain nutrition and growth. This includes patients who are critically unwell, require respiratory support, surgical intervention, ongoing investigations or are not tolerating enteral feeds. At these times, supplementation with IV fluids may be required to maintain optimal hydration and nutrition.

• Effective fluid and electrolyte management of neonates and infants in NICU requires;
  • A physical assessment
  • Assessment of fluid status
  • Haemodynamic monitoring of fluid balance (including any losses) 
  • Administration of the appropriate fluids and electrolytes.  
  • Assessment of risk factors for complications (such as critically unwell, preterm, or patients with gastrointestinal disorders).

• Inadequate management can lead to complications such as dehydration, fluid overload and hyponatremia. 

Aim

To provide guidance on the assessment and management of adequate hydration and fluid balance in neonates and infants admitted to the Butterfly Ward. To guide clinicians caring for unwell neonates and infants to appropriately assess and recognise signs and symptoms of fluid imbalances (such as dehydration or fluid overload) ensuring prompt escalation and management.

This guideline focuses on the fluid assessment and management of Butterfly inpatients, which ranges from preterm and term newborns right through to older infants who are also managed within the Butterfly ward. Nursing staff caring for neonates and young infants admitted to other areas of RCH can utilise this guideline but should also refer to local guidelines. 

Definition of Terms

Overview of fluid related adaptation in newborns (term and preterm)

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 of life; extracellular fluid volumes and insensible water losses increase as weight and gestational age decrease.

Therefore, appropriate management of fluid and electrolytes must take into consideration:

• Birth weight
• Gestational age and corrected age.
• Unwell term or preterm neonate
• Disease pathophysiology

All of these factors 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.

Total Body Water (TBW)

In neonates, TBW distribution gradually changes with increasing gestational age, from the extreme preterm with TBW constituting 90% of body weight, to the term neonate with 75%. 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 cardiopulmonary adaption. 

Fetal urine flow steadily increases with gestational age reaching 25 to 50 mL/hr at term and dropping to 8 – 16mL/hr (1-3mL/kg/hr) at birth reflecting the large exchange of TBW during fetal life and the abrupt change occurring with cardiopulmonary adaption after birth. Additionally, glomerular filtration rates (GFR) are low in utero remaining low at birth and gradually increasing in the neonatal period. With a changing GFR and variable urine concentration, all newborns undergo a diuresis in the days following birth resulting in a reduction of TBW.

Contraction/ the reduction of TBW accounts for early postnatal weight loss. This results in a 10-15% weight loss in those born preterm and 5-10% weight loss in term babies.

Assessment

Indications for IV Fluids:

• Dehydration
• Hypoglycaemia
• Nil by Mouth
• Feed Intolerance
• Gastric losses replacement

Monitoring:

• Continuous oxygen saturation and cardiorespiratory monitoring is required for Butterfly ward patients requiring administration of IV fluids. Patients should be assessed and monitored hourly.
• Target observations should be established during ward rounds and vital signs breaching normal ViCTOR chart ranges must be escalated and discussed with the senior nursing team (TSN, ANUM) and medical team (Registrar/ Fellow/ Consultant). 
• Refer to RCH Nursing Guideline: Observation and Continuous Monitoring for the requirement of monitoring of RCH ward inpatients.
  

Physical Examination 

It is important to complete a full head-to-toe assessment, using a systematic approach.  This should be performed at the commencement of each nursing shift and more frequently if there any concerns or changes.  Any changes to activity level or may be a sign of fluid depletion and dehydration and should be escalated promptly, following a thorough assessment.

Physical assessment of hydration status includes the assessment of:

• Weight on alternate days (for patients with renal or cardiac conditions see chart below)
• Presence and severity of oedema
• Skin turgor and colour, including capillary refill time
• Mucous membranes
• Periorbital tissue
• Anterior fontanelle
• Altered conscious state
• Gastric losses (NGT, Stoma, Vomiting, diarrhoea, stoma)
• Urine output

Physical signs can be used in the assessment of fluid status however may at times be unreliable and therefore must be observed within the context of 

• Body weight 
• Haemodynamic monitoring 
• Haematocrit 
• Serum biochemistry 
• Acid-base status 
• Urine output.

Refer to RCH Nursing Assessment Guideline for more details. 

Table 1- Patient Examination in Assessment of fluid status:

Table created by RCH Butterfly Nurse Educator, Nov 2024.

Urine Output 

• It is important to assess, calculate and document urine output and review the trend (from previous days). Not only does this indicate fluid intake but also renal perfusion.
• Calculate urine output mL/kg/hr (see examples below).
• Correct administration of maintenance fluids should aim to produce a urine output of
  >1mL/Kg/hour in most circumstances.
• If urine output is <1mL/Kg/hour, repeated reassessment of clinical condition and hydration status should be made and acted upon.
• Urine output can vary, and targets should be discussed with the treating medical team.
• Any concerns of reduced urine output should be appropriately escalated through nursing and medical pathways.
• Clinical review is required for patients with a urine output above 6 mL/hr. A urine output above 8 mL/hr may require replacement fluid of urine losses to avoid dehydration but will require consideration of individual patient circumstances by Neonatologist.
• Please refer to below guideline Butterfly Replacement of Renal Losses Guideline for further information.

To calculate urine output:

Urine volume ÷ patient weight ÷ number of hours from 0600

OR

Urine volume ÷ patient weight ÷ number of hours since last nappy change / IDC chamber empty 

Volume of urine divided by patient weight divided by number of hours from 0600 OR Urine volume divided by patient weight divided by number of hours since last nappy change/IDC chamber empty (e.g. 2 or 4 hours).

Example Urine output calculation:

Baby B weighs 3 kg and has passed 27 mL of urine over a 6-hour time frame.

To calculate urine output for Baby B:

27 mL (total urine) divided by 3 kg (weight) divided by 6 (hours) equals 1.5 mL/kg/hr

It is important to also consider changes in urine output trends, which may mean calculating urine output over different time frames. If the expectation for Baby B was the production of 1mL/kg/hr urine and a urinary catheter was in situ, then Baby B would need to produce 3 mL of urine in the chamber each time it was measured and emptied.

3 ml/ hr divided by 3 (kg) = 1mL/kg/hr

Example calculating over longer time frame

It is now 1800 and Baby B's urine output is 72mL in total. 

Urine output divided by time in hours since 0600 divided by weight

72mL divided by 12 (hrs) divided by 3 (kg) = Urine output of 2mL/kg/hr

Other Investigations and Monitoring 

Serum Biochemistry

All Butterfly patients receiving IV Fluids for acute conditions:

• Check serum electrolytes and glucose before commencing the infusion (where possible).
•  Repeat bloods in 24 hours or sooner if clinically indicated.
• Serum electrolytes and glucose should be checked at a minimum every 24 – 48 hours thereafter.

Changes in serum sodium concentration should be assessed in the context of total body weight hydration status and any recent increase or decrease in weight. The requirement of both sodium (Na+) and potassium (K+) is 2 – 4 mmoL/kg/24 hours. 

Acid base status

Along with serum electrolyte and glucose monitoring, patients receiving IV fluids will also require blood gases to assist with assessing fluid and hydration status.  

Variations in the metabolic components of the blood gas (bicarbonate, base excess and anion gap) can be indications of fluid status imbalance.

A metabolic acidosis can be suggestive of decreased intravascular volume and hyperosmolarity.

• A decreasing Base Excess (BE) (increasing base deficit) in the context of decreased urine output, decreased mean arterial pressure and a prolonged CRT is suggestive of dehydration.
  • Normal base excess (BE) = -3 to +3 mEq/L

• A widening anion gap is reflective of dehydration with a deceased intravascular volume as lactic acidosis follows poor tissue perfusion.
  • Normal anion gap = 8 – 16 mEq/L

Haematocrit

The haematocrit is a measure of the proportion of blood that is made up of cells, expressed as a fraction. In the neonatal period, a physiologic increase in haematocrit occurs due to a fluid shift away from the intravascular compartment.  An increase in haematocrit can also occur because of dehydration due to a decrease in plasma volume. 

Table 2- Haematocrit Level Ranges for NICU Patients

Total Fluid Intake (TFI)

If a neonate weighs less than their birth weight, use the birth weight as the working weight in a fluid calculation, unless specified by the medical team. A TFI will be discussed and determined on the ward round and should account for all requirements and possible risk factors. The TFI will be documented within the MAR fluid order and progress notes.

The TFI can be divided into sections to account for any feeds, TPN, IV fluids and medication infusions.  The TFI should be calculated at the commencement of each nursing shift and following any changes, such as infusion rates or upgrading feeds.

Example 1

Baby A weighs 3.5 kg and a TFI of 100 mL/kg has been set. She is NBM and has no infusions. This weight will be used to calculate the rate of her maintenance fluid of 10% dextrose with additives.

100 (mL/kg/day) x 3.5 (kg) = 350 mL/day

To calculate the hourly rate:

350 (mL/day) divided by 24 (hours) = 14.58 mL/hr

This can be rounded to 14.6 mL/hr

The TFI can be divided further into portions to account for any feeds, TPN and medication infusions.

Example 2

Baby B has commenced feeds at 15 mL/kg/day (2 hrly).  He has a current TPN N2 infusion at 100 mL/kg/day and has a morphine infusion running at 10 mcg/kg/hr at 0.5 mL/hr. He weighs 2.4 kg.  TFI handed over at change of shift = 120 mL/kg/day.

Feeds

15 (mL/kg/day) x 2.4 (kg) = 36 mL/day

To achieve the feed bolus:

36 (mL/day) divided by 12 feeds = 3 (mL/ feed) every 2 hours.

N2

100 (mL/kg/day) x 2.4 (kg) = 240 (mL/day)

240 (mL/day) divided by 24 (hours) =10 (mL/hr)

Morphine (calculate volume for TFI volume only)

0.5 (mL/hr) x 24 (hours)= 12 (mL/day)

12 (mL/day) divided by 2.4 (kg) = 5 (mL/ kg/day)

Therefore TFI:

15 mL/kg/day (feeds) + 100 mL/kg/day (n2) + 5 mL/kg (infusion) = 120 mL/kg/day.

Management

The fluid choice and volume required should be discussed and clearly communicated on the ward round and documented in the patient’s EMR notes. The fluid requirement and TFI needs to consider risk factors for overload, renal impairment, current venous access and other infusions and medications required or being administered as well as the projected time that intravenous fluids may be expected to be required.

Standard Intravenous Fluid 

As previously described, neonates undergo a diuresis within the first 24 hours of life and therefore electrolyte additives are not required during this time, unless clinically indicated.  Glucose is the main source of energy for the brain. Glucose homeostasis reduces the risk, and associated complications, of hypoglycaemia.

Table 3- Standard IV Fluids used in NICU, RCH

Total Parenteral Nutrition (TPN) 

TPN is usually commenced if a patient on Butterfly Ward is not likely to be fed enterally for longer than 3 days. It is prescribed by the Medical Staff in conjunction with the Pharmacist and Clinical Nutrition team.

Refer to RCH Departmental Guideline: Parenteral nutrition in NICU

Table 4- TPN Solutions most often prescribed for NICU Patients

All TPN solutions are hyperosmolar and careful observation of infusion sites must occur if administered peripherally. 

Table 5- Intravenous Fluid and Parenteral Requirement (ml/kg/day)

Glucose Infusion Rate (GIR)

The neonatal liver normally produces 6 – 8mg/kg/min of glucose, which is the approximate basal requirement of a newborn neonate. The GIR is a measurement of how much glucose (as mg/kg/min) a neonate is receiving. When a neonate has hypoglycaemia or is fluid restricted, their GIR should be calculated to make sure they are receiving an adequate amount of glucose.

Initially these ranges can be used as a guide:

Term Neonates: 4-6mg/kg/min

Premature Neonates: 6-8mg/kg/min

The Glucose Delivery Calculator (NICU Tools) allows you to calculate the GIR of the neonate – including IV and enteral intake.

Line Selection for Intravenous Infusion 

• The concentration of glucose and/or amino acids in any intravenous fluid and the use of inotropes must be considered in determining the appropriate site for infusion: central or peripheral.
• Refer to RCH Policies and Procedures: Insertion, Management and removal of central venus access devices for more information on maintenance of CVAD devices, including standard procedures, blood sampling and troubleshooting.
• Refer to RCH Departmental Guideline: Vasoactive Drug Infusion Management NICU and RCH Departmental Guideline: Butterfly Common Infusions resources for more details.
• Compatibilities of multiple infusions can be checked via Paediatric Injectable Guidelines, Lexicomp,
• Inform the medical team if additional intravenous access is required to ensure compatible fluids are separated appropriately.

Table 6- Infusions that Require a CVAD

Checking Procedure 

IV fluids are to be checked by two RNs at the commencement of therapy, with rate and bag changes, and at handover timers as per the OILs RCH Policies and Procedures: Standarised Checking for Infusion Pump Programming. 

An hourly volume to be infused (VTBI) must be set. This ensures the appropriate hourly volume has been infused and is a prompt to complete the hourly site assessment and EMR LDA flowsheet documentation.  Every hour the volume infused (VI) is to be cleared from the pump, documented in the EMR flowsheets and a new volume to be infused (VTBI) must be set. 

Administration

On Butterfly ward, TPN bag, line and filter; SMOF syringe and line; and IV fluids with additives prepared on the ward (bags and syringes), should be changed every 24 hours. 
Pre-prepared fluid bags can remain hanging for up to a maximum of 7 days. Please refer to RCH Policy and Procedure: Central Venous Access Device for further information.

Labelling 

All patients with intravenous fluids require labels on the fluid bag, the syringe and the IV line (closest to the patient). Refer to RCH Policies and Procedures: User Applied Labelling of Injectable Medicines, Fluids and Lines excluding Perioperative Environments. 

Documentation

• Physical Assessment: Initial and ongoing physical assessments should be documented in the primary assessment and focused assessment flowsheets within EMR. 
• Observations: Observations should be documented within the observation flowsheet. Observations breaching normal ViCTOR chart ranges must be escalated and discussed with ANUM and medical teams. Document this discussion in the progress notes, including reason for escalation, and any planed changes in care.
• Fluid orders: Fluids are ordered within the MAR. The associated TFI, along with any alterations to standard regimes should be clearly documented in the progress notes.
• Fluid Balance: The 24-hour fluid balance period begins at 0600. This provides a full 24-hour fluid balance to be reviewed on morning ward round and to enhance decision making. In some situations, formal review may be required more frequently, such as at a 12 hourly timeframe.

Escalation of Care

It is vital that any concerns with patient care (such as signs of dehydration, fluid overload, tachypnoea, increased or reduced urine output) are addressed and appropriately escalated through nursing and medical pathways to ensure that patients are assessed in a timely manner and provided appropriate management.

RCH has developed oneTEAM as a tool for parents, carers and staff to seek support for patients if they are concerned at any point.

Special Considerations 

Inadequate/Inappropriate fluid management can lead to complications such as dehydration, fluid overload and hyponatremia. 

Insensible Water Loss (IWL)

Prematurity: An important variable influencing IWL is the maturity of neonatal skin, with greater IWL occurs in preterm babies resulting from evaporation through the immature epithelial layer and the greater surface area of the skin in relation to weight.

Phototherapy: Phototherapy may increase IWL and therefore fluid intake may need to be increased by 10 – 20 mL/kg/day. Refer to RCH Nursing Guideline: Phototherapy for Neonatal Jaundice and RCH Nursing Guideline:Environmental Humidity for Premature Neonates.

Fluid Restriction: In some cases, such as in the immediate post-operative period, patients with HIE or patients with a PDA, fluid restriction may be an appropriate strategy to avoid fluid overload. 

Other Considerations

• It may be necessary to provide haemodynamic support to ensure adequate cardiac output in neonates and infants following extensive surgery. 
• The administration of vasoactive medications may contribute to tachycardia and should be taken into consideration and discussed with the neonatologist.
• Pain may also result in tachycardia and not be an indicator of fluid volume depletion.
• Careful assessment of the patient in the event of hypovolaemia is necessary to ensure the adequate and appropriateness of fluid boluses.
• Refer to Butterfly cardiovascular guideline for more details on the management of neonatal patients with cardiovascular compromise.

Albumin replacement

Routine screening for hypoalbuminemia may be required for critically unwell neonates, particularly those who are at risk of fluid overload.  Occasionally 20% albumin replacement is administered as part of the management of a patient with hypoalbuminemia and fluid overload.  Targets for albumin levels and necessity for administration of 20% albumin replacement will be determined by neonatologist on ward round. It is important to remember that albumin is a blood product and should be used sparingly and only when necessary.

Further details can be found at RCH Albumin Administration- Paediatric Albumin Guidance.

Electrolyte imbalances

The administration of electrolyte corrections may be required for critically unwell neonates who experience electrolyte imbalances. The decision to correct electrolytes will be made by the neonatologist on a risk vs benefit basis while considering the patients intravenous access, other infusions.

Central access is likely to be required and all sources of intravenous potassium must be included when calculating replacement doses and infusion rates. To ensure the safe administration of any electrolyte corrections on Butterfly ward, refer to specific electrolyte replacement guidelines.

Gastrointestinal Losses

Gastrointestinal losses (e.g. nasogastric losses, faecal stoma losses) 20 mL/kg and above require mL for mL replacement.  Standard Replacement Fluid is 0.9% Sodium Chloride (500 mL) + 10 mmoL Potassium Chloride. Refer to Replacement of neonatal gastrointestinal losses.

Clinical performed ultrasound

On Butterfly, on some occasions ultrasounds have been performed to assess a patient’s intravascular volume and cardiac output, further supporting management goals.  The need for this will be determined by the Neonatologist.

Renal Impairment

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 

Some patient groups may be at risk of developing AKI which will impact assessment and management, particularly in relation to their fluid management.  Neonates and infants with congenital heart disease, HIE, NEC and those exposed to nephrotoxic medications are examples of patient groups who may be at risk. Patients with AKI may require more frequent weights and assessments of fluid status and electrolytes. It may be necessary to monitor urine output more closely with insertion of a urinary catheter.

Fluid Resuscitation

If fluid resuscitation is required for Butterfly patients:

• To be given as rapidly as possible
• May be repeated as necessary

Common intravenous fluid for resuscitation:

Family Considerations 

It is the responsibility of the clinician caring for the neonate or infant to ensure that the family understands the rationale for the administration of IV fluids. Discuss any concerns they may have and update them of any changes.

Ensure parents or caregivers are aware of the oneTEAM process and how it may be utilised on Butterfly if they have any ongoing concerns. 

Companion Documents

RCH Clinical Practice Guidelines

• Dehydration
  
• Intravenous fluids
• Intravenous access - Peripheral

RCH Departmental Guidelines

• Albumin Administration
• Butterfly Replacement of Neonatal Gastrointestinal Losses Guideline
  
• PICC and CVAD lines
• Vasoactive Drug Infusion Management NICU
  
  

RCH Nursing Guidelines

• Therapeutic Hypothermia in the Neonate
• Observation and continuous monitoring
• Ward Management of a neonate

RCH Policies and Procedures

• Insertion, Management and Removal of Cental Venus Access Devices
• User applied labelling of injectable medicines, fluids and lines excluding perioperative environment
• Standardised Checking for Infusion Pump Programming (OILS) 

Other RCH resources

OneTEAM