How to Write the Order for D5W at 100 mL/hr in Hypernatremia
For an adult patient with hypernatremia, order: "D5W (5% Dextrose in Water) IV at 100 mL/hr continuous infusion" with hourly blood glucose monitoring for the first 2 hours, then every 2-4 hours thereafter. 1, 2
Standard Order Components
The complete order should include:
- Fluid type: D5W (5% Dextrose in Water) 3, 1
- Route: Intravenous (IV) 3, 1
- Rate: 100 mL/hr 1, 2
- Duration: Continuous infusion until hypernatremia corrected 3
- Monitoring: Blood glucose every 1-2 hours initially 1, 2
Why D5W is the Correct Choice for Hypernatremia
D5W delivers zero renal osmotic load after dextrose metabolism, making it the preferred fluid for hypernatremic states. 3, 4 This is critical because:
- Salt-containing solutions like 0.9% NaCl have tonicity (~300 mOsm/kg H₂O) that exceeds typical urine osmolality, requiring approximately 3 liters of urine to excrete the osmotic load from 1 liter of isotonic fluid, which risks worsening hypernatremia 3
- D5W becomes hypotonic once dextrose is metabolized, providing free water without sodium load 4
- The 100 mL/hr rate provides slow, controlled correction of plasma osmolality 4
Rate Selection Rationale
The 100 mL/hr rate is appropriate because:
- This represents the standard maintenance rate for adults (approximately 100 mL/kg per 24 hours for a 70 kg adult) 1, 2
- It delivers approximately 5 grams of dextrose per hour, sufficient to prevent hypoglycemia while avoiding hyperglycemia 2
- This rate allows gradual sodium correction without exceeding recommended limits 3, 5
Critical Monitoring Requirements
Blood glucose must be monitored every 1-2 hours when initiating D5W infusions. 1, 2 Additionally:
- Check serum sodium every 2-4 hours initially to ensure appropriate correction rate 3
- Monitor for signs of fluid overload, particularly in patients with cardiac or renal compromise 1, 2
- Assess clinical response including mental status and vital signs 3
Important Caveats
In patients with cardiac or renal compromise, limit D5W to ≤100 mL/hr and monitor closely for fluid overload. 1, 2 Although D5W provides minimal plasma volume expansion (only 80-100 mL per liter expands plasma volume), these patients remain at risk 4.
Avoid isotonic saline (0.9% NaCl) in hypernatremia. 3 The high sodium content will worsen hypernatremia rather than correct it, particularly in patients with impaired urinary concentration ability 3, 4.
Correction Rate Considerations
While traditional teaching suggests limiting sodium correction to ≤0.5 mEq/L per hour, recent evidence shows that rapid correction in critically ill adults is not associated with increased mortality or neurologic complications 5. However, the 100 mL/hr D5W rate naturally provides gradual correction, which remains the safest approach 3, 1.
Slower correction rates (<0.25 mEq/L/hr) are actually associated with higher mortality in severe hypernatremia. 6 The key is adequate correction—not overcautious undercorrection—while avoiding overly rapid shifts 6.
Pediatric Modifications
For children, use weight-based calculations instead of fixed rates 3, 1:
- First 10 kg: 100 mL/kg/24h
- 10-20 kg: 50 mL/kg/24h
- Remaining weight: 20 mL/kg/24h