When is D5 (Dextrose 5%) 1/2 NS (Normal Saline) used as maintenance IV fluids?

When to Use D5 1/2 NS as Maintenance IV Fluids

D5 1/2 NS (5% dextrose in 0.45% saline) should NOT be used as routine maintenance IV fluid in most hospitalized patients, as current evidence strongly favors isotonic solutions to prevent hospital-acquired hyponatremia. 1

Current Evidence-Based Recommendations

Standard Maintenance Fluid Choice

• The American Academy of Pediatrics strongly recommends isotonic solutions (D5 0.9% NS or D5 Lactated Ringer's) for maintenance IV fluids in children aged 28 days to 18 years to significantly decrease the risk of developing hyponatremia 1

• The European Society of Pediatric and Neonatal Intensive Care recommends isotonic balanced solutions with glucose for most hospitalized children in acute and critical care settings 1

• Hypotonic fluids like D5 1/2 NS increase the risk of hyponatremia at 12 and 24 hours compared to isotonic solutions 2

• The fall in serum sodium is significantly greater with hypotonic dextrose saline (like D5 1/2 NS) compared to isotonic normal saline, with a mean difference of 3.0 mmol/L 3

Limited Scenarios Where D5 1/2 NS May Be Appropriate

Specific Clinical Context

• D5 1/2 NS may be considered in cerebral malaria with volume depletion where the goal is to provide dextrose to prevent hypoglycemia while minimizing salt that could leak into pulmonary and cerebral tissues 1

• Patients requiring correction of hypernatremia may need hypotonic fluids, though this should be done with careful monitoring and specific correction protocols 1

• Patients with documented syndrome of inappropriate antidiuresis (SIAD) who are euvolemic and require free water replacement may occasionally need hypotonic solutions, but this is a specialized scenario requiring close monitoring 1

Critical Pitfalls to Avoid

• Do not use D5 1/2 NS routinely in hospitalized children or adults, as acutely ill patients frequently have elevated arginine vasopressin (AVP) from pain, nausea, stress, postoperative states, or pulmonary/CNS disorders, which impairs free-water excretion 1

• Hospital-acquired hyponatremia from hypotonic fluids can cause hyponatremic encephalopathy, a medical emergency that can be fatal or lead to irreversible brain injury 1

• Approximately 15-30% of hospitalized patients develop hyponatremia, and hypotonic maintenance fluids significantly contribute to this risk 1

• Even when using isotonic fluids, patients receiving IV medications containing free water or consuming additional free water enterally remain at risk for hyponatremia and require monitoring 1

Monitoring Requirements When Any Maintenance Fluid is Used

• Check serum sodium within 24 hours of starting maintenance IV fluids, especially in high-risk patients 4

• Monitor electrolytes at least daily in all patients receiving maintenance IV fluids 1, 5

• If neurologic symptoms develop (unexplained nausea, vomiting, headache, confusion, lethargy), measure electrolytes immediately as these may indicate hyponatremic encephalopathy 1

• Patients at high risk (post-surgical, ICU patients, those with large GI losses or on diuretics) require more frequent laboratory monitoring 1

The Historical Context

• The traditional practice of using hypotonic fluids like D5 1/2 NS was based on the 1957 Holliday-Segar recommendations, which were theoretical and not based on clinical trials 1

• Over the past decade, increasing evidence has demonstrated the deleterious effects of hyponatremia in acute care settings with hypotonic maintenance solutions 1

• The incidence of mild and moderate hyponatremia is significantly higher with 0.45% saline (half-normal saline) compared to 0.9% saline at 12 hours (p<0.001) and 24 hours (p<0.001) 2