Isotonic Intravenous Fluids Are Preferred in Infants and Children
For maintenance intravenous fluid therapy in infants (28 days and older) and children, isotonic fluids (0.9% NaCl or near-isotonic solutions like lactated Ringer's) are strongly preferred over hypotonic fluids to prevent hospital-acquired hyponatremia. 1
Key Recommendation
The American Academy of Pediatrics Clinical Practice Guideline definitively recommends isotonic or near-isotonic maintenance IVFs for most hospitalized children from 28 days to 18 years of age who require intravenous fluid support. 1
Rationale for Isotonic Fluids
Prevention of Hyponatremia
- Hyponatremia (serum sodium <135 mEq/L) affects 15-30% of hospitalized patients and represents the most common electrolyte abnormality in acute care settings. 1
- Acutely ill infants and children frequently have conditions that trigger excess arginine vasopressin (AVP) release—including pain, nausea, stress, postoperative states, pneumonia, and meningitis—which impairs free-water excretion. 1
- When hypotonic fluids are administered in the presence of AVP excess, patients develop syndrome of inappropriate antidiuresis (SIAD) or SIAD-like states, leading to water retention and potentially life-threatening hyponatremic encephalopathy. 1
Appropriate Fluid Compositions
The following isotonic or near-isotonic solutions are recommended: 1
- D5 0.9% NaCl (5% dextrose in 0.9% normal saline): 154 mEq/L sodium, 308 mOsm/L
- D5 lactated Ringer's: 130 mEq/L sodium, 273 mOsm/L
- PlasmaLyte with 5% dextrose: 140 mEq/L sodium, 294 mOsm/L
Clinical Context and Application
Applicable Patient Populations
This guideline applies to: 1
- Infants ≥28 days old (excluding NICU patients)
- Children and adolescents up to 18 years
- Medical and surgical (postoperative) acute-care settings
- Critical care and general inpatient ward settings
Excluded Populations
The isotonic fluid recommendation does not apply to: 1
- Neonates <28 days old or in the NICU
- Patients with neurosurgical disorders
- Congenital or acquired cardiac disease
- Hepatic disease, cancer, or renal dysfunction
- Diabetes insipidus
- Voluminous watery diarrhea or severe burns
Important Clinical Considerations
Fluid Prescription Approach
- IVFs should be prescribed, ordered, dosed, and delivered like any other medication, with careful attention to tonicity, electrolyte composition, and glucose content. 1
- The tonicity of IVF is primarily determined by sodium and potassium concentration, not by osmolality alone (urea affects osmolality but not tonicity). 1
Common Pitfall to Avoid
Historical practice favored hypotonic fluids (such as D5 0.45% NaCl or D5 0.2% NaCl) for pediatric maintenance IVF, but this approach has been definitively shown to cause unacceptably high rates of hospital-acquired hyponatremia. 1 This outdated practice should be abandoned in favor of isotonic solutions for the vast majority of hospitalized infants and children requiring maintenance fluids.
Monitoring Requirements
While the guidelines emphasize fluid composition, they also acknowledge the need for appropriate electrolyte monitoring, though specific monitoring protocols require individualized clinical judgment based on the patient's underlying condition and clinical trajectory. 1