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IV Fluids in PICU

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Standard "Maintenance" Intravenous Fluids

Age Mixture
Less than 6 months
0.9% saline§ + 10% glucose
±40mmol/L Potassium Chloride†‡
0.9% saline§ + 5% glucose 1000ml bag
Add
• 100ml of 50% glucose
• ±40mmol Potassium Chloride†‡
6 months and older
0.9% saline + 5% glucose*
+40mmol/L Potassium Chloride
0.9% saline + 5% glucose* 1000ml bag
Add
• 40mmol Potassium Chloride

These apply to all children in PICU with the following exceptions:

* Children greater than 6 months with any brain problem will receive 0.9% sodium chloride +40mmol potassium chloride/1000ml and add glucose only if required.
Children less than 6 months after CPB: omit KCL on the day of operation.
Add KCl the following day if K<5mmol/L
Children in whom the arterial or venous K is greater than 5mmol/L: omit KCl
§ Newborn infants on the day of birth receive 10% glucose and do not need any added Sodium or Potassium. These are added on day 2.

Intravenous Fluid Volumes

Standard "maintenance" intravenous fluid volumes for reasonably well children can be worked out from the formula:

  • 4 ml/kg/hr for the 1st 10kg plus
  • 2 ml/kg/hr for the 2nd 10kg plus
  • 1 ml/kg/hr for every kg > 20kg (maximum 100ml/hr)

Most PICU children need considerably less water than this. High ADH secretion (IPPV, brain injury, sepsis) reduce need by at least 30%. Humidified gases reduce need about 25%. Radiant heaters may increase need by up to 20-50%.

Standard total intravenous fluid volumes for PICU children should be:

  • 67% (⅔) maintenance for sick children (maximum 70ml/hr) 
  • 50% (½) maintenance for ventilated children (maximum 50ml/hr)

Since this is total fluids, sicker children with multiple infusions will have little if any "maintenance" fluid. These children, especially neonates, may require a 50% glucose infusion to maintain blood glucose >3.5mmol/L.

The serum sodium is a useful index of body water. If low, the commonest cause is free water excess and the treatment is water restriction. Assessment of the cause may require urinary sodium measurement. High sodium usually indicates free water deficit for which the treatment is increased intravenous or enteral water.

Enteral feeding

While it is important to water restrict ICU children, they should not be severely calorie restricted. Breast milk and infant formulae are generally about 0.67cal/ml. Paediatric and adult formulae are usually 1cal/ml. Feeding should be started early as per the "PICU enteral feeding guidelines."

Enteral feed goals are usually determined from the standard maintenance formula and not reduced for sickness/ventilation. When feeds are being absorbed, total enteral fluids can therefore be increased to full "maintenance" and sometimes more.

TPN

The IV fluid rules apply. Once infusions are accounted for, this often means that TPN is delivered in 50-60 ml/kg/day of water. TPN should only be started in children in whom it is anticipated that enteral feeding will not be established within 5-7 days. It may be started earlier in neonates and chronically ill malnourished children.

Ongoing excessive losses

Ongoing excessive losses should be replaced. The commonest site is from the upper gut. The usual replacement for this is 0.9% sodium chloride with 20mmol/500ml KCl.

Maintenance of catheter patency

Arterial catheters are infused with 0.9% sodium chloride with:

  • 5unit/ml heparin if weight ≥2.5kg
  • 1unit/ml heparin if weight <2.5kg

Central venous, pulmonary artery and left atrial catheters are each to be infused with 5% glucose with 1unit/ml heparin.

All infants < 5kg with a central venous catheter are to receive low dose heparin (10unit/kg/hr; see low dose heparin protocol). For children after surgical procedures, this is to be started 4 hours after return from the operating room provided there is no significant bleeding.

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  • Date last published: 03 August 2009
  • Document type: Clinical Guideline
  • Services responsible: Paediatric Intensive Care Unit
  • Owner: Brent McSharry
  • Editor: John Beca