Should hypernatremia correction with D5W (Dextrose 5% in Water) in a postoperative patient with acute kidney injury (AKI) on chronic kidney disease (CKD) be done slowly over 48 hours?

Hypernatremia Correction in Postoperative AKI on CKD

Yes, hypernatremia correction with D5W should be done slowly over 48 hours (or longer) in a postoperative patient with AKI on CKD, with a maximum correction rate of 8-10 mmol/L per 24 hours to prevent cerebral edema and neurological injury. 1

Correction Rate Guidelines

The maximum safe correction rate for chronic hypernatremia is 8-10 mmol/L per 24 hours, with a target rate of 0.5 mmol/L per hour or less. 1 This slower correction prevents osmotic water shift into brain cells, which can cause cerebral edema, seizures, and permanent neurological damage 1. For a patient with hypernatremia requiring correction over 48 hours, this translates to approximately 4-5 mmol/L per day, which is well within safe limits.

Why Slower Correction is Critical in AKI on CKD

Patients with renal impairment face unique challenges:

• Impaired sodium and water handling: AKI on CKD means the kidneys cannot appropriately regulate sodium excretion or concentrate urine, making overcorrection more likely 2
• Risk of rapid shifts: Without normal renal function to buffer changes, administered free water can cause more dramatic shifts in serum sodium 2, 3
• Postoperative stress: The postoperative state adds metabolic derangements that complicate electrolyte management 4

D5W Administration Protocol

Calculate free water deficit using: Free water deficit (L) = 0.5 × body weight (kg) × [(current Na/140) - 1] 1

Key administration principles:

• Administer D5W at a controlled rate to achieve target correction of 0.5 mmol/L per hour or less 1
• Monitor serum sodium every 2-4 hours initially, then every 6-8 hours once stable 1
• Adjust infusion rate based on serial sodium measurements to avoid overcorrection 1
• Account for ongoing losses (urine output, insensible losses) in addition to calculated deficit 1

Special Considerations for AKI on CKD

If the patient requires renal replacement therapy (RRT):

• Standard dialysate/replacement fluids (sodium 140 mEq/L) will cause rapid overcorrection 4, 2
• Add calculated amounts of D5W prefilter to prevent overcorrection while maintaining adequate effluent volumes 4
• A simplified equation can determine D5W rate based on prescribed effluent volume 4
• Alternatively, customize replacement fluid by adding sterile water to achieve a fluid sodium concentration that matches the desired target serum sodium 3

Avoid isotonic fluids (0.9% NaCl) in patients with renal concentrating defects, as this will worsen hypernatremia rather than correct it 1. The impaired kidneys cannot excrete the sodium load, leading to further elevation of serum sodium 1.

Monitoring Requirements

Serial measurements are mandatory:

• Serum sodium every 2-4 hours during initial correction 1
• Urine output and urine electrolytes to assess renal response 1
• Daily weights to track fluid balance 1
• Adjust therapy if sodium corrects too rapidly (>0.5 mmol/L/h) by slowing free water administration 1

Common Pitfalls to Avoid

• Never correct faster than 8-10 mmol/L per 24 hours in chronic hypernatremia, as this risks cerebral edema 1
• Do not use isotonic saline in patients with impaired renal concentrating ability 1
• Inadequate monitoring during active correction can lead to overcorrection complications 1
• Failing to account for ongoing losses will result in undercorrection 1
• In patients on CRRT, using standard replacement fluids without modification will cause rapid overcorrection 4, 2