What is the rationale for choosing normal saline (0.9% sodium chloride) versus half normal saline (0.45% sodium chloride) for maintenance intravenous (IV) fluid in pediatric patients?

From the Guidelines

For pediatric maintenance IV fluids, isotonic solutions like normal saline (0.9% NaCl) are preferred over hypotonic solutions like half-normal saline (0.45% NaCl) to prevent hospital-acquired hyponatremia. This recommendation is based on the clinical practice guideline published in Pediatrics in 2018 1, which suggests that isotonic fluids should be administered to children who are acutely ill and require maintenance IVFs. The use of hypotonic IVFs has been associated with severe hyponatremia, resulting in deaths and serious injuries, as reported by the Institute for Safe Medical Practices and the United Kingdom's national safety alert 1.

Key Considerations

• Isotonic fluids, such as normal saline, more closely match plasma osmolality and reduce the risk of hyponatremia 1.
• The recommended approach is to start with isotonic fluids (normal saline) for most children requiring maintenance fluids, then adjust based on the patient's clinical status, electrolyte levels, and underlying conditions.
• For maintenance rates, the 4-2-1 rule can be followed: 4 mL/kg/hr for the first 10 kg, plus 2 mL/kg/hr for 10-20 kg, plus 1 mL/kg/hr for each kg above 20 kg.
• Regular monitoring of electrolytes, especially sodium, is essential when administering any IV fluids to children, with adjustments made based on laboratory results and clinical status 1.

Special Considerations

• Certain conditions may warrant the use of hypotonic fluids, such as hypernatremia, significant free water losses, or conditions predisposing to sodium retention.
• The subcommittee's review of 7 additional clinical trials involving 1316 children and adolescents supported the use of isotonic maintenance IVFs in children who are acutely ill for the prevention of hospital-acquired hyponatremia 1.

From the Research

Maintenance IV Fluid Rationale

Normal Saline vs 1/2 Normal Saline in Pediatrics

• The choice between normal saline and 1/2 normal saline for maintenance IV fluid in pediatrics depends on various factors, including the patient's underlying condition and electrolyte balance 2.
• In patients with hyponatremia, isotonic saline (such as normal saline) may be used to treat hypovolemia, while fluid restriction and diuresis may be used in euvolemia and hypervolemia, respectively 2.
• A study comparing the effects of normal saline and half normal saline on serum electrolytes during the recovery phase of diabetic ketoacidosis in children found that half normal saline resulted in a significant decrease in corrected serum sodium, while normal saline led to hyperchloremia and nonanion gap acidosis 3.
• The use of half normal saline may be beneficial in preventing hyperchloremia and nonanion gap acidosis, but providers should be cautious of the potential decrease in serum-corrected sodium 3.
• Larger trials are needed to study the clinical significance of these findings and to determine the optimal choice of maintenance IV fluid in pediatric patients 3.