Maintenance Fluid Requirements for Pediatric Patients
Use the Holliday-Segar formula to calculate maintenance fluid requirements: 100 ml/kg/day for the first 10 kg, plus 50 ml/kg/day for the next 10 kg, plus 25 ml/kg/day for each kg above 20 kg. 1
Calculation Method by Weight
The hourly rate calculation translates to: 2
- 4 ml/kg/hour for the first 10 kg of body weight 1, 2
- 2 ml/kg/hour for weight between 10-20 kg 1, 2
- 1 ml/kg/hour for each kg above 20 kg 1, 3
Practical Example
For a 30 kg child, calculate as follows: 3
- First 10 kg: 10 kg × 4 ml/kg/h = 40 ml/h
- Next 10 kg: 10 kg × 2 ml/kg/h = 20 ml/h
- Remaining 10 kg: 10 kg × 1 ml/kg/h = 10 ml/h
- Total maintenance rate = 70 ml/h 3
Fluid Composition
Administer isotonic fluids (0.9% saline or balanced crystalloids) as maintenance therapy in hospitalized children, especially during the first 24 hours. 2, 4 This recommendation is based on strong evidence showing that hypotonic fluids significantly increase the risk of hospital-acquired hyponatremia and potentially fatal hyponatremic encephalopathy. 1, 4
Electrolyte Supplementation
- Sodium requirements: 1-3 mmol per 100 kcal 4
- Potassium requirements: 1-3 mmol per 100 kcal 4
- Add potassium supplementation of 20-40 mEq/L (2/3 KCl and 1/3 KPO4) once renal function is confirmed and serum potassium is known 4
- Chloride intake should be slightly lower than the sum of sodium and potassium intakes (Na + K - Cl = 1-2 mmol/kg/day) to prevent iatrogenic metabolic acidosis 1, 2
Glucose Provision
Include glucose in sufficient amounts to prevent hypoglycemia but avoid excessive amounts that cause hyperglycemia, with monitoring at least daily. 2
Clinical Situations Requiring Volume Adjustment
Increased ADH Secretion Risk
For acutely and critically ill children at risk of increased antidiuretic hormone secretion, restrict maintenance fluid volume to 65-80% of the calculated Holliday-Segar volume to prevent hyponatremia and fluid overload. 2, 4
Organ Failure States
For children with heart failure, renal failure, or hepatic failure, restrict maintenance fluid volume to 50-60% of the calculated volume. 2, 4
Increased Fluid Requirements
Water requirements increase with: 1, 4
- Fever
- Hyperventilation
- Hypermetabolism
- Gastrointestinal losses
Decreased Fluid Requirements
Water requirements decrease with: 1, 4
- Renal failure
- Congestive heart failure
- Critical illness with mechanical ventilation
- Temperature-controlled environments
Total Fluid Accounting
Calculate total daily maintenance fluid by including all sources: IV fluids, blood products, all IV medications, arterial/venous line flushes, and enteral intake. 2, 4 This prevents "fluid creep" and fluid overload, which is defined as >10% increase in cumulative fluid balance from baseline and is an independent predictor of morbidity, mortality, prolonged mechanical ventilation, and increased length of stay. 4
Monitoring Requirements
Reassess fluid balance and clinical status at least daily in acutely and critically ill children. 2, 4
- Monitor serum electrolytes regularly, especially sodium levels 2, 4
- Monitor glucose at least daily 2
- Ensure induced change in serum osmolality does not exceed 3 mOsm/kg/hour during fluid replacement 4
Common Pitfalls to Avoid
Failing to adjust maintenance rates in special clinical scenarios (organ failure, increased ADH states) leads to adverse outcomes including hyponatremia and fluid overload. 3 The traditional Holliday-Segar formula was developed for healthy children with normal caloric expenditure and urinary output, not for hospitalized patients with complex physiologic derangements, decreased urinary output, and elevated antidiuretic hormone levels. 5
Continuing hypotonic maintenance fluids in hospitalized children significantly increases the risk of hospital-acquired hyponatremia. 1, 4 Multiple meta-analyses and randomized controlled trials have documented this increased risk compared to isotonic fluids. 1