What is the appropriate dose and administration guidelines for a 0.45% sodium chloride (half‑normal saline) bolus given over one hour?

0.45% Sodium Chloride Bolus Administration

For adult patients with hyperglycemic crises (DKA/HHS), 0.45% sodium chloride should be administered at 4-14 ml/kg/hour (not as a traditional "bolus" over 1 hour) when corrected serum sodium is normal or elevated, following initial resuscitation with 0.9% normal saline. 1, 2

Key Administration Guidelines

Initial Resuscitation Phase

The term "bolus" is somewhat misleading in this context. According to established diabetes care guidelines:

• First hour: Always use 0.9% isotonic saline at 15-20 ml/kg/hour (approximately 1-1.5 liters in average adults) for initial volume expansion and restoration of renal perfusion 1, 2, 3
• This aggressive initial phase is critical regardless of sodium status

Subsequent Fluid Therapy with 0.45% Saline

After the initial hour, transition to 0.45% NaCl is appropriate when:

• Corrected serum sodium is normal or elevated
• Infusion rate: 4-14 ml/kg/hour (continuous infusion, not a rapid bolus) 1, 2, 3

For a 70 kg adult, this translates to approximately 280-980 ml/hour

Critical Calculation

• Correct serum sodium for hyperglycemia: For each 100 mg/dl glucose above 100 mg/dl, add 1.6 mEq to the measured sodium value 2
• If corrected sodium is low, continue with 0.9% NaCl instead 1, 2

Electrolyte Supplementation

Once renal function is confirmed:

• Add 20-30 mEq/L potassium to the 0.45% saline solution
• Use 2/3 KCl and 1/3 KPO4 1, 2, 3

Safety Monitoring

Rate of Correction

• Osmolality change should not exceed 3 mOsm/kg/hour 1, 2
• Fluid replacement should correct estimated deficits within 24 hours 1, 2

High-Risk Patients

In patients with cardiac or renal compromise:

• Monitor serum osmolality continuously
• Perform frequent cardiac, renal, and mental status assessments
• Risk of iatrogenic fluid overload is significant 1, 2

Common Pitfalls

1. Never use 0.45% saline for initial resuscitation - this can worsen hypotension and organ perfusion
2. Don't administer as a rapid 1-hour bolus - the 4-14 ml/kg/hour represents a continuous infusion rate
3. Always correct sodium for hyperglycemia first - uncorrected values will lead to inappropriate fluid selection
4. Monitor for hyperchloremic acidosis - while less common with 0.45% saline than 0.9% saline, it remains a consideration with large volumes 4

Pediatric Considerations

For children (<20 years):

• Initial hour: 0.9% NaCl at 10-20 ml/kg/hour
• Subsequent therapy: 0.45-0.9% NaCl (depending on sodium levels) at 1.5 times maintenance requirements (approximately 5 ml/kg/hour)
• Critical: Avoid rapid fluid administration due to cerebral edema risk 2

The evidence consistently shows that 0.45% saline is a maintenance/correction fluid, not a rapid bolus fluid, and should only be used after initial volume resuscitation with isotonic saline in the context of hyperglycemic crises.