What is the recommended maintenance fluid for pediatric patients with hypotonic dehydration?

Maintenance Fluid for Pediatric Hypotonic Dehydration

Use isotonic crystalloid solutions (0.9% sodium chloride or balanced crystalloids like PlasmaLyte) with 5% dextrose and appropriate potassium chloride as maintenance fluid for pediatric patients with hypotonic dehydration. 1, 2

Fluid Composition

Isotonic solutions (sodium 135-154 mEq/L) are strongly recommended over hypotonic fluids for maintenance therapy in hospitalized children aged 28 days to 18 years. 1 The American Academy of Pediatrics provides a strong recommendation (Level A evidence) that isotonic solutions with appropriate potassium and dextrose significantly decrease the risk of developing hyponatremia compared to hypotonic fluids. 1

Specific Fluid Options:

• 0.9% sodium chloride (154 mEq/L sodium) in 5% dextrose 1
• PlasmaLyte (140 mEq/L sodium) in 5% dextrose - preferred as a balanced crystalloid 1, 2
• Hartmann solution (131 mEq/L sodium) - acceptable alternative 1

Balanced crystalloid solutions should be favored over 0.9% sodium chloride when available, as they reduce length of stay in both critically ill (Level B evidence) and acutely ill patients (Level A evidence). 2

Evidence Supporting Isotonic Fluids

The recommendation is based on 17 randomized controlled trials involving 2,455 patients, with 16 of 17 studies demonstrating that isotonic fluids were superior to hypotonic fluids in preventing hyponatremia. 1 The number needed to treat with isotonic fluids to prevent hyponatremia (sodium <135 mEq/L) is 7.5 across all studies. 1

Multiple international guidelines converge on this recommendation: both the 2018 AAP guidelines and the 2022 ESPNIC guidelines support isotonic maintenance fluids. 1 The ESPGHAN/ESPEN guidelines similarly document substantial evidence supporting isotonic fluid use for maintenance hydration in hospitalized children. 1

Additional Components

Dextrose:

Add 2.5-5% dextrose to prevent hypoglycemia. 1 Monitor blood glucose at least daily to guide glucose provision. 2

Potassium:

Add appropriate potassium chloride (1-3 mmol/kg/day) based on clinical status and regular monitoring to avoid hypokalemia. 1, 2

Volume Calculation

Use the Holliday-Segar formula for calculating maintenance fluid requirements: 1

• First 10 kg: 100 mL/kg/day (4 mL/kg/hour)
• 10-20 kg: Add 50 mL/kg/day (2 mL/kg/hour) for each kg above 10 kg
• Above 20 kg: Add 25 mL/kg/day (1 mL/kg/hour) for each kg above 20 kg

Important Volume Modifications:

• Patients with heart failure, renal failure, or hepatic failure: Restrict to 50-60% of calculated volume 2
• Patients at risk of increased ADH secretion: Consider restricting to 65-80% of calculated volume 2, 3
• Account for all fluid sources to avoid fluid overload and cumulative positive fluid balance 2

Monitoring Requirements

Perform regular reassessment at least daily: 2

• Serum sodium levels
• Fluid balance (input/output)
• Clinical status
• Blood glucose levels

Common Pitfalls to Avoid

Do not use hypotonic solutions (0.45% saline, 0.3% saline, or 0.18% saline) for maintenance therapy. 1, 2 These significantly increase the risk of iatrogenic hyponatremia, which can lead to hyponatremic encephalopathy with irreversible neurological morbidity and mortality. 1, 4

Do not fail to account for all sources of fluid when calculating total maintenance volume, as this leads to "fluid creep" and fluid overload, which prolongs mechanical ventilation and extends length of stay. 2

Do not use lactated Ringer solution as maintenance fluid, as it was not studied in the clinical trials supporting these guidelines and no safety recommendations can be made. 1

Applicable Patient Population

These recommendations apply to children 28 days to 18 years of age in surgical (postoperative) and medical acute-care settings, including critical care and general inpatient wards. 1

Exclusions:

This guideline does NOT apply to: 1

• Neonates younger than 28 days or in the NICU
• Adolescents older than 18 years
• Patients with neurosurgical disorders
• Congenital or acquired cardiac disease
• Hepatic disease
• Cancer
• Renal dysfunction
• Diabetes insipidus
• Voluminous watery diarrhea
• Severe burns

For these excluded populations, individualized fluid management based on specific disease pathophysiology is required. 1