When is 23 percent (twenty-three percent) hypertonic saline used to treat hyponatremia?

Use of 23% Hypertonic Saline in Hyponatremia Treatment

23% hypertonic saline is specifically used for severe symptomatic hyponatremia with evidence of cerebral edema, increased intracranial pressure, or in cases of subarachnoid hemorrhage where rapid correction of sodium levels is needed to prevent neurological deterioration.

Indications for 23% Hypertonic Saline

• Severe symptomatic hyponatremia with:

  • Seizures
  • Coma
  • Decreased level of consciousness
  • Respiratory distress
  • Evidence of brainstem herniation

• Subarachnoid hemorrhage (SAH) with increased intracranial pressure 1

  • Studies show 23.5% hypertonic saline can improve cerebral blood flow in SAH patients
  • Associated with mortality benefit when cerebral blood flow is enhanced 1

Clinical Evidence Supporting Use

Research demonstrates that 23.5% hypertonic saline can:

• Rapidly reduce cerebral edema
• Decrease intracranial pressure
• Increase regional cerebral blood flow
• Improve brain tissue oxygen levels
• Enhance pH in patients with high-grade subarachnoid hemorrhage 2

Administration Protocol

1. Bolus administration:

   • 23% hypertonic saline is typically given as small volume boluses (30-60 mL)
   • Used in emergency situations requiring immediate sodium correction

2. Safety monitoring:

   • Serum sodium should be measured within 6 hours of administration
   • Re-administration should not occur until serum sodium is <155 mmol/L 1
   • Target correction rate: 4-6 mEq/L within first 1-2 hours for severely symptomatic patients 3

Important Precautions

• Avoid overcorrection:

  • Do not exceed 8 mEq/L in 24 hours to prevent osmotic demyelination syndrome 2
  • Higher risk patients (alcoholism, malnutrition, liver disease) require more cautious correction 2

• Highest risk of osmotic demyelination occurs when:

  • Correction exceeds 10 mEq/L in 24 hours
  • Patient has chronic hyponatremia (>48 hours) 4

Alternative Hypertonic Solutions

For less severe cases, other concentrations are preferred:

• 3% hypertonic saline: Standard for most symptomatic hyponatremia cases
  • Administered as 100 mL boluses up to three times at 10-minute intervals 2, 5
• 7.5% hypertonic saline: Used in traumatic brain injury and stroke patients 1

Algorithm for Hypertonic Saline Selection

1. Assess symptom severity:

   • Mild/moderate symptoms (nausea, headache, weakness): Use 3% hypertonic saline
   • Severe symptoms (seizures, coma, respiratory distress): Consider 23% hypertonic saline

2. Evaluate underlying condition:

   • Subarachnoid hemorrhage with increased ICP: 23% hypertonic saline may be beneficial
   • Traumatic brain injury: 3-7.5% solutions typically sufficient

3. Monitor response:

   • Check sodium levels frequently (every 2-4 hours initially)
   • Adjust treatment based on clinical response and sodium correction rate

Pitfalls to Avoid

• Overcorrection risk: Studies show overcorrection occurs in 4.5-38% of patients, with higher rates in severely symptomatic patients 5, 6

• Misdiagnosis of symptom severity: Symptoms caused by hypovolemia can be misinterpreted as severely symptomatic hyponatremia 6

• Failure to monitor diuresis: Increased diuresis correlates with higher risk of sodium overcorrection 6

In summary, while 23% hypertonic saline is effective for specific severe cases, it requires careful monitoring and should be reserved for situations where rapid correction of sodium levels is necessary to prevent neurological deterioration, particularly in subarachnoid hemorrhage patients with increased intracranial pressure.