D5W Infusion Rate for Severe Hypernatremia in an 80-Year-Old Patient
For an 80-year-old patient with severe hypernatremia, initiate D5W at 100 mL/hour as the starting rate, which provides controlled correction while avoiding salt-containing solutions that would worsen the hypernatremia. 1, 2
Rationale for D5W Selection
D5W is the fluid of choice for hypernatremic dehydration because it delivers zero renal osmotic load after dextrose metabolism, unlike isotonic saline which has a tonicity (~300 mOsm/kg H₂O) that exceeds typical urine osmolality and would require approximately 3 liters of urine to excrete the osmotic load from just 1 liter of fluid, risking serious worsening of hypernatremia. 1
- Salt-containing solutions like 0.9% NaCl should be strictly avoided in hypernatremic states 1
- D5W becomes hypotonic once dextrose is metabolized, providing free water for correction 3
Initial Rate Calculation
Start with 100 mL/hour based on standard maintenance fluid requirements for adults (25-30 mL/kg/24h for a typical 70-80 kg patient). 1, 2
- This translates to approximately 1,800-2,400 mL per 24 hours for maintenance 1
- The 100 mL/hour rate provides slow, controlled decrease in plasma osmolality 1, 3
Critical Correction Parameters
The rate must be adjusted to ensure sodium correction does not exceed 8-10 mEq/L per 24 hours to prevent cerebral edema from overly rapid correction. 1
- Monitor serum sodium every 2-4 hours initially 1
- Calculate water deficit: approximately 4 mL/kg × body weight × (current Na - 140) 1
- Plan correction over 48-72 hours for chronic hypernatremia 4
Age-Specific Considerations for 80-Year-Old Patients
Elderly patients require more cautious fluid administration due to increased risk of cardiac and renal compromise. 2, 5
- Limit D5W to ≤100 mL/hour in patients with cardiac or renal compromise 2, 5
- Monitor closely for fluid overload despite minimal plasma volume expansion from D5W 3
- Consider that only 80-100 mL per liter of D5W expands plasma volume, with most water shifting intracellularly 3
Monitoring Protocol
Check serum sodium every 2 hours initially when severe hypernatremia is present (Na >170 mEq/L), then every 4-6 hours once stabilizing. 1, 2
- Monitor blood glucose every 1-2 hours when initiating D5W to prevent hyperglycemia 2, 5
- Assess for signs of fluid overload (especially in elderly): jugular venous distension, pulmonary edema 2
- Track urine output and daily weights 1
Rate Adjustment Algorithm
If sodium is correcting too rapidly (>0.5 mEq/L/hour or >10 mEq/L in 24 hours):
If sodium is not correcting adequately (<4 mEq/L in 24 hours) and patient remains symptomatic:
- Increase D5W rate by 25-50 mL/hour 1
- Consider adding free water via nasogastric tube if tolerated 6
- Reassess for ongoing losses (fever, hyperventilation, diabetes insipidus) 1
Common Pitfalls to Avoid
Never use isotonic saline (0.9% NaCl) for hypernatremia correction—this is the most critical error that will worsen hypernatremia. 1
- Avoid correcting sodium faster than 8-10 mEq/L per 24 hours to prevent cerebral edema 1, 4
- Do not assume standard maintenance rates are sufficient—calculate based on water deficit and ongoing losses 1
- In elderly patients, do not exceed 100 mL/hour without careful cardiac monitoring 2, 5
- Remember that D5W provides minimal volume expansion (~80-100 mL plasma expansion per liter), so it corrects hypernatremia through free water provision, not volume resuscitation 3