Why is hypertonic saline (Intracranial Pressure) ICP used for control?

Hypertonic Saline for Intracranial Pressure Control

Hypertonic saline is used for intracranial pressure (ICP) control because it creates an osmotic gradient across the blood-brain barrier, drawing water from brain tissue into the intravascular space, thereby reducing cerebral edema and lowering ICP. 1

Mechanism of Action

• Hypertonic saline causes a transient increase in extracellular space osmolarity, creating an osmotic pressure gradient across the blood-brain barrier that results in water displacement from brain tissue to the hypertonic environment, effectively reducing cerebral edema 1
• Maximum effect occurs after 10-15 minutes and typically lasts for 2-4 hours, making it an effective treatment for acute elevations in ICP 1
• The osmotic effect leads to dehydration of brain tissue while cerebral blood volume remains largely unaffected 2

Efficacy in ICP Reduction

• Hypertonic saline has been proven effective at reducing ICP in traumatic brain injury (TBI) and subarachnoid hemorrhage (Grade A evidence) 3
• Studies show that 7.5% hypertonic saline can decrease ICP by an average of 8.3 mmHg, with more significant reductions (up to 14.2 mmHg) observed in patients with higher baseline ICP values (>31 mmHg) 4
• Hypertonic saline has demonstrated efficacy even in patients with ICP refractory to standard treatments including mannitol and barbiturates 5

Dosing and Administration

• For acute ICP reduction, a bolus dose of 7.5% hypertonic saline (250 mL) administered over 15-20 minutes is recommended 1
• In severe cases, 23.4% hypertonic saline (30 mL infused over 15 minutes) has been shown to effectively reduce ICP 4
• Continuous infusions typically utilize 3% hypertonic saline and may be effective in children with TBI and patients with stroke or acute liver failure 3
• Target serum sodium concentration should be 145-155 mmol/L 1

Comparison with Other Osmotic Agents

• Hypertonic saline should be used instead of (not in conjunction with) mannitol for reducing ICP 3
• Hypertonic saline may be preferred in patients with hypovolemia and has shown superior efficacy compared to mannitol in several studies 1
• 7.5% saline (2 mL/kg) has been shown to significantly reduce both the number and duration of intracranial hypertension episodes compared to equivalent doses of mannitol 1

Monitoring and Safety Considerations

• Serum sodium levels should be measured within 6 hours of bolus administration and should not exceed 155 mmol/L 1
• Re-administration may be considered if ICP remains elevated, but only after confirming serum sodium is <155 mmol/L 1
• Concentrated sodium chloride solutions must be diluted prior to administration to prevent complications such as hypernatremia, cardiovascular shock, CNS disorders, and renal damage 6
• Patients with impaired kidney function require careful monitoring due to potential aluminum toxicity with prolonged parenteral administration 6

Important Limitations and Caveats

• Despite effectiveness in reducing ICP, there is no evidence that hypertonic saline improves neurological outcomes (Grade B) or survival (Grade A) in patients with raised ICP 3
• Potential complications include electrolyte abnormalities, pulmonary edema, and diabetes insipidus 7
• The ICP-lowering effect may be transient in some patients with head trauma, requiring repeated administration (approximately every 2-3 hours) or addition of other therapies 5, 2
• Response to hypertonic saline varies by etiology, with better responses typically seen in traumatic brain injury and postoperative edema compared to non-traumatic intracranial hemorrhage or cerebral infarction 7