When is 5% dextrose in 0.45% normal saline indicated?

When is D5 0.45% Normal Saline (D5.45NS) Indicated?

D5 0.45% normal saline is primarily indicated for maintenance fluid therapy in diabetic ketoacidosis (DKA) once serum glucose reaches 250 mg/dL, for pediatric maintenance fluids after initial resuscitation, and for gradual correction of hypernatremia when both glucose and sodium replacement are needed. 1, 2

Primary Clinical Indications

Diabetic Ketoacidosis Management

• Switch from isotonic saline to D5 0.45% NS when serum glucose falls to 250 mg/dL during DKA treatment to prevent hypoglycemia while continuing insulin therapy to clear ketoacidosis 1, 2
• The fluid should include 20-30 mEq/L potassium (2/3 KCl and 1/3 KPO4) until the patient is stable and can tolerate oral supplementation 1
• Monitor serum glucose hourly during acute resuscitation, then every 2-4 hours once stable 2
• The goal is to gradually reduce blood glucose by 50-100 mg/dL per hour 3

Pediatric Maintenance Fluids

• After initial volume expansion with isotonic saline in children, D5 0.45% NS is appropriate for continued rehydration when serum sodium is normal or elevated 2
• Infusion rate should typically be 1.5 times the 24-hour maintenance requirements (approximately 5 mL/kg/h) 1
• The initial fluid resuscitation in pediatric patients should not exceed 50 mL/kg over the first 4 hours to prevent cerebral edema 1, 3
• Include 20-40 mEq/L potassium (2/3 KCl or potassium-acetate and 1/3 KPO4) once renal function is assured 1

Hypernatremia Correction

• D5 0.45% NS can be used for gradual correction of hypernatremia when combined sodium and glucose replacement is needed 2
• Ensure the osmolality correction rate does not exceed 3 mOsm/kg H₂O per hour to prevent cerebral edema 1, 2
• For pure hypernatremia without volume depletion, D5 water (without sodium) is preferred over D5 0.45% NS 4, 2

Critical Contraindications

When NOT to Use D5 0.45% NS

• Never use in hypotension or shock states - these require isotonic crystalloids like 0.9% normal saline at 5-10 mL/kg in the first 5 minutes 1, 4
• Avoid in patients with CNS disorders, respiratory distress, or cerebral hypoxia - the hypotonic nature after glucose metabolism worsens cerebral edema 4, 2
• Do not use in stroke patients - glucose-containing solutions can have detrimental effects in acute brain injury 2
• Contraindicated in traumatic brain injury where 0.9% saline is first-line therapy 2

Monitoring Requirements

Essential Parameters to Track

• Monitor serum osmolality to ensure the induced change does not exceed 3 mOsm/kg H₂O per hour 1, 2
• Assess cardiac, renal, and mental status frequently during fluid resuscitation to avoid iatrogenic fluid overload 1, 2
• In pediatric patients, particularly close observation for cerebral edema is required during osmolality correction 2
• Monitor for hyperglycemia development, which can cause osmotic diuresis and worsen outcomes 2

Special Population Considerations

• Geriatric patients require careful monitoring for fluid overload and pulmonary edema 2
• Patients with renal or cardiac compromise need frequent reassessment to prevent pulmonary edema 1, 2
• In children under 20 years, monitor mental status closely to rapidly identify changes indicating iatrogenic complications 1, 2

Common Pitfalls to Avoid

• Do not use D5 0.45% NS for initial resuscitation - always start with isotonic saline (0.9% NaCl) at 15-20 mL/kg/h in adults or 10-20 mL/kg/h in children 1
• Avoid rapid correction of hypernatremia - the rate should not exceed 8 mEq/day to prevent osmotic demyelination 2
• Do not ignore the hypotonic nature - D5 0.45% NS can contribute to hyponatremia and cerebral edema in vulnerable populations 2
• Ensure potassium supplementation is included once renal function is confirmed, as both DKA and fluid therapy can cause significant potassium shifts 1