Paediatric Maintenance Fluids

Maintenance fluids supply water and electrolytes to children who cannot take adequate oral intake. They are prescribed from weight, adjusted for conditions that change losses, and with sodium monitored because hypotonic fluid causes hospital-acquired hyponatraemia.

Volume. 100 mL/kg/day for the first 10 kg, 50 mL/kg/day for the next 10 kg, and 20 mL/kg/day for each kg over 20, up to about 2 litres a day in girls and 2.5 litres in boys. The hourly equivalent is 4 mL/kg/h for the first 10 kg, 2 mL/kg/h for the next 10 kg and 1 mL/kg/h thereafter. Example: 14 kg child, 1200 mL/day, about 48 to 50 mL/h.

• Fluid of choice beyond the neonatal period: isotonic fluid with glucose, usually 0.9% sodium chloride with 5% glucose, with potassium chloride 20 mmol/L added once urine is passing and potassium is not raised. Balanced isotonic solutions with glucose are an alternative.
• Neonates, term, day 1: 10% glucose at 60 mL/kg/day, increasing by 15 to 30 mL/kg each day to 150 mL/kg/day by day 4 to 5. Glucose infusion rate 4 to 6 mg/kg/min in term infants. Sodium is added from day 2 to 3 (2 to 4 mmol/kg/day) once weight loss and sodium allow, and potassium from day 2 once urine is passing.
• Enteral feeds replace intravenous fluids as soon as tolerated. Count milk volume against the intravenous total.

Hypotonic fluids. Avoid 0.18% sodium chloride with 4% glucose and similar solutions in hospital, particularly after surgery, with meningitis, bronchiolitis, pneumonia or raised intracranial pressure, because antidiuretic hormone secretion is high.

Reduce. Consider two thirds of maintenance in conditions that raise antidiuretic hormone, such as meningitis, pneumonia, bronchiolitis, postoperative states and raised intracranial pressure, if sodium is normal and monitored. Practice differs between units, and some use full maintenance with isotonic fluid and close sodium checks.

Increase. Add about 10% for each degree Celsius over 38, and extra for phototherapy, radiant warmers, high environmental heat, burns and polyuria.

Hyponatraemia. Sodium under 135 mmol/L needs review of fluid type and volume. Symptomatic hyponatraemia (seizure, vomiting with drowsiness): 2 mL/kg of 3% sodium chloride over 10 to 20 minutes, repeated up to twice, under senior direction.

Special groups. Infants with cardiac failure, renal failure or nephrotic syndrome need restricted volumes. In East Africa, severe malnutrition needs cautious fluids and low-sodium solutions, and oral or nasogastric route is preferred.

Monitoring. Check sodium, potassium and glucose before starting and then at least every 24 hours, and every 6 to 12 hours for high-risk infants. Weigh daily, record intake and urine output, and watch for oedema and weight gain over 5% in 24 hours.

Referral and escalation. Escalate for sodium under 130 or over 150 mmol/L, a fall in sodium of more than 0.5 mmol/L/h, urine output under 1 mL/kg/h, or neurological symptoms.

Stopping. Stop intravenous fluids when oral or enteral intake reaches two thirds of maintenance needs, and wean over 24 hours.