How to administer 3% sodium chloride (hypertonic saline) in suspected encephalitis with elevated intracranial pressure (ICP) and normal sodium levels?

Administration of 3% Hypertonic Saline in Suspected Encephalitis with Raised ICP and Normal Sodium

For patients with suspected encephalitis and elevated intracranial pressure (ICP), 3% hypertonic saline should be administered as a 250 ml bolus over 15-20 minutes through a peripheral IV, with repeat doses every 2-3 hours as needed, while maintaining serum sodium below 155 mmol/L and osmolarity below 320 mOsm/L. 1

Dosing Protocol

• Initial dose: 250 ml of 3% hypertonic saline administered over 15-20 minutes
• Administration route: Can be safely given through peripheral IV access 2
• Repeat dosing: Every 2-3 hours as needed for ICP control
• Maximum frequency: Average of 7 boluses in 12 hours for refractory cases 1

Monitoring Requirements

• Serum sodium: Check before each bolus and every 6 hours during treatment
• Target sodium level: Maintain below 155 mmol/L
• Serum osmolarity: Keep below 320 mOsm/L 1, 3
• ICP monitoring: Continuous monitoring during administration when possible

Safety Parameters

• Contraindications to repeat dosing: Serum sodium >155 mmol/L 3
• Administration rate: Boluses can be safely administered at rates up to 999 mL/hr without increased risk of extravasation or phlebitis 2
• Head position: Elevate head of bed to 30° to facilitate venous drainage

Indications for Use in Encephalitis

• Primary indication: Refractory intracranial hypertension (ICP >20-25 mmHg for >5 minutes)
• Secondary indication: Acute neurological deterioration with clinical signs of increased ICP 1
• Timing: Should be administered as soon as possible after lumbar puncture confirms diagnosis, unless contraindicated 3

Special Considerations

• If lumbar puncture is contraindicated due to suspected raised ICP, CT scan should be performed first, followed by hypertonic saline administration if significant brain shift is present 3
• For patients with suspected encephalitis who cannot undergo immediate lumbar puncture, hypertonic saline can be administered based on clinical signs of increased ICP
• In patients with normal sodium levels, careful monitoring is still required as sodium levels may rise quickly with repeated boluses

Efficacy and Limitations

• Hypertonic saline is effective at reducing raised ICP (Grade A evidence) but does not improve neurological outcomes (Grade B) or survival (Grade A) 3
• The treatment should be part of a comprehensive approach to managing encephalitis with raised ICP

Potential Complications

• Hypernatremia
• Hyperchloremic metabolic acidosis
• Phlebitis (though rare with proper administration)
• Central pontine myelinolysis (with very rapid sodium correction)

This protocol provides a clear approach to administering 3% hypertonic saline in suspected encephalitis with raised ICP while maintaining normal sodium levels through careful monitoring and dosing adjustments.