Guidelines for Fluid Management in Infants and Children on PICU

• Introduction
  1. Normal maintenance requirements for intravenous and enteral fluids
  2. Replacement of pre-existing fluid deficit and ongoing fluid losses
  3. Fluid requirements for post-operative cardiac surgical patients
  4. Types of fluid to be used including potassium requirements
• Appendix 1: Guideline for the preparation of 10% glucose + 0.9% sodium chloride intravenous solution at ward level
• Appendix 2: Guideline for the preparation of 10% glucose + 0.45% sodium chloride intravenous solution at ward level

Introduction

These guidelines apply to infants and children on the Paediatric Intensive Care Unit (PICU). They include:

1. Normal maintenance requirements for intravenous and enteral fluids
2. Replacement of pre-existing fluid deficit and ongoing fluid losses
3. Fluid requirements for post-operative cardiac surgical patients
4. Types of fluid to be used including potassium requirements

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1. Normal maintenance fluid requirements

(a) Intravenous fluid requirements

A child’s maintenance fluid requirement decreases proportionately with increasing age. For practical purposes either of the following calculations may be used to estimate the approximate maintenance requirement of children according to weight.

Example calculation for 35 kg child:
Method 1: (10 x 100) + (10 x 50) + (15 x 20) = 1800ml/day = 75ml/hr
Method 2: (10 x 4) + (10 x 2) + (15 x 1) = 75ml/hr

Quick reference guide:

(b) Enteral feed requirements

Age >6 months
For children above 6 months of age the enteral requirement is equal in volume to the IV requirement and the above calculation can be used.

Age <6 months
For young infants there is often confusion about the difference between oral and IV fluid requirements. Their water requirement is the same for both routes of administration; however infants need larger volumes of milk (see below) to provide adequate nutrition.

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2. Replacement of pre-existing fluid deficit and ongoing fluid losses

In addition to normal maintenance fluid requirements, unwell children may need:

• Fluid resuscitation for shock
• Replacement of pre-existing fluid losses
• Replacement of on-going fluid losses, including insensible losses

(a) Fluid resuscitation for shock

Give a bolus of 10-20ml/kg. The following can be used as fluid boluses on PICU:

• Crystalloid in most cases - Hartmann’s solution
• Colloid - in specific circumstances only - 4.5% Human Albumin Solution (HAS)

Always reassess, and repeat as necessary. Blood products may be used for fluid resuscitation when clinically appropriate.

The exception to this would be in a post operative cardiac patient who should be given fluid resuscitation in 5-10ml/kg aliquots with reassessment after each bolus.

(b) Replacement of pre-existing fluid losses

The water deficit can be calculated following an estimation of the degree of dehydration as a percentage of body weight. A 10kg child who has lost 1kg due to fluid loss will be 10% dehydrated. To calculate the fluid deficit:

Fluid deficit (ml) = weight (kg) x % dehydration x 10

This deficit should be replaced, usually over 24 hours. In some instances replacement of the deficit over 48 hours is more appropriate (such as diabetic ketoacidosis and hypernatremia dehydration). For specific fluid management issues relating to certain conditions please see separate guidelines (DKA, liver failure).

(c) Replacement of ongoing fluid losses

Nasogastric losses should usually be replaced ml for ml with 0.9% sodium chloride + added potassium chloride 10mmol per 500ml (increased to 20mmol per 500ml if needed). For surgical patients, confirm with the surgeon responsible the volume they wish to replace.

Chylous chest drain losses should be half replaced with 4.5% Human Albumin Solution (HAS). If there is significant blood loss with a falling haemoglobin post operatively then replace with packed red cells.

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3. Post operative cardiac surgical patients

After cardiopulmonary bypass there is a tendency for sodium and water retention in conjunction with a systemic inflammatory response that results in increased capillary permeability. Fluid administration in the first 24 hours is aimed at maintaining an optimal haemodynamic state. These patients often have low serum potassium in the first 48 hours and so potassium chloride should be added to maintenance fluids unless the patient is not passing any urine.

Fluid restriction in the immediate post-operative period:

Continue this fluid regime until the morning after surgery. Following that time, maintenance fluids will be reviewed twice daily on ward rounds. When a decision is taken to liberalise fluid intake, fluids should be increased by 10-20 % per day.

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4. Types of fluid to be used

Wherever possible, enteral feeds should be given.

The intravenous fluids listed in the table on page 4 are all available for use in PICU patients. An isotonic fluid is now recommended as the routine maintenance fluid in most infants and children. The exceptions to this are:

• Newborns, who handle sodium and water differently and so require less sodium initially
• Special situations such as diabetic ketoacidosis and diabetes insipidus, whose fluid management should always be supervised by a consultant

Which fluid you use depends on the individual circumstances, the patient’s age, serum sodium and glucose. In most situations, 5% glucose + 0.9% sodium chloride with potassium chloride 10mmol per 500ml is a safe fluid to start with. In infants less than 3 months of age, the glucose component should be made up to 10% glucose.

Potassium chloride (10mmol per 500ml) should be added unless there is a contraindication (hyperkalaemia, anuria or acute kidney injury). This will provide the daily potassium requirement of around 2mmol/kg/day. This should be increased to 20mmol  potassium chloride per 500ml if needed.

Additional notes on types of fluid

The routine use of 5% glucose + 0.45% sodium chloride is no longer recommended, except for infants <28 days of age. It may be used with caution >28 days of age in certain circumstances after discussion with the PICU consultant. It should not be used in any patients with a serum sodium <138.

The routine use of 4% glucose + 0.18% sodium chloride is not recommended. It may only be used with caution in exceptional circumstances after discussion with the PICU consultant. This is because the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is common in infants and children who are unwell, and the combination of SIADH plus administration of 0.18% sodium chloride can lead to water retention, cerebral oedema and herniation.

In children at risk of SIADH (such as meningitis, encephalitis, respiratory infections, post-operative) fluids should initially be restricted to 50-80% maintenance. Once on full enteral feeds, total maintenance should be increased to 100%.

All children on IV fluids should have serum electrolytes, glucose, hydration status and fluid balance monitored and their fluid therapy adjusted accordingly. Daily weight can also be helpful and should be considered in patients with complex fluid management problems.

Fluids available for use in PICU patients

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