What is the management approach for a patient with elevated intracranial pressure and a normal sodium level?

Management of Elevated Intracranial Pressure with Normal Sodium (138 mmol/L)

With a sodium level of 138 mmol/L and elevated intracranial pressure, you should administer hypertonic saline (7.5% at 250 mL or 3% as continuous infusion) targeting a serum sodium of 145-155 mmol/L, as this has been proven to effectively reduce ICP while your patient's current sodium level provides a safe therapeutic window. 1, 2

Initial Hyperosmolar Therapy Selection

Your patient's normal sodium level (138 mmol/L) is actually advantageous—it provides room to safely increase sodium to the therapeutic target range without risk of excessive hypernatremia. The most recent high-quality guidelines recommend:

• Administer 7.5% hypertonic saline at 250 mL as a bolus over 15-20 minutes for acute ICP elevation, which is the most effective treatment according to the American College of Surgeons 2
• Target serum sodium concentration of 145-155 mmol/L to effectively reduce intracranial pressure 1, 2
• The maximum ICP-lowering effect occurs at 10-15 minutes and lasts 2-4 hours 2

Hypertonic Saline vs. Mannitol Decision

Use hypertonic saline instead of mannitol in this clinical scenario for several reasons:

• Hypertonic saline should be used instead of and not in conjunction with mannitol, as they have comparable efficacy at equiosmotic doses (about 250 mOsm) 2
• The 2023 Critical Care Medicine guidelines found that hypertonic saline significantly decreased ICP over 24 hours compared to standard care (RR 0.79 for mortality from intracranial hypertension, though not statistically significant) 1
• Meta-analysis shows a trend favoring hypertonic sodium solutions over mannitol, with a weighted mean difference in ICP reduction of 1.39 mm Hg 3
• Hypertonic saline may be preferred in patients with hypovolemia, whereas mannitol can worsen dehydration 2

Specific Dosing Protocol

For acute ICP management:

• Bolus therapy: 250 mL of 7.5% hypertonic saline over 15-20 minutes 2
• Alternative: 30 mL of 23.4% hypertonic saline (though 7.5% is more commonly recommended) 2, 4
• Continuous infusion: 3% hypertonic saline can be used for sustained control, particularly validated in pediatric populations with mean treatment duration of 7.6 days 2

For mannitol (if hypertonic saline unavailable):

• 0.25 to 2 g/kg body weight as 15-25% solution over 30-60 minutes 5
• In small or debilitated patients, 500 mg/kg may be sufficient 5

Critical Monitoring Parameters

Measure serum sodium within 6 hours of bolus administration and implement the following monitoring protocol:

• Do not re-administer hypertonic saline until serum sodium is <155 mmol/L 1, 2
• Monitor fluid, sodium, and chloride balances to prevent complications 2
• The American Heart Association recommends avoiding sodium levels exceeding 155-160 mmol/L to prevent complications 2
• Majority of patients have peak sodium levels <155 mmol/L after bolus therapy with proper monitoring 2

Important Clinical Caveats

Outcome expectations: 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 intracranial pressure 1, 2. This is a critical counseling point for families.

Avoid rapid correction: Do not correct sodium too rapidly to prevent osmotic demyelination syndrome, though no cases have been reported with proper monitoring even with bolus doses of 23.4% hypertonic saline 2

Contraindications to consider:

• Well-established anuria due to severe renal disease (for mannitol) 5
• Severe pulmonary congestion or frank pulmonary edema (for mannitol) 5
• Active intracranial bleeding except during craniotomy (for mannitol) 5

Specific Context for Acute Liver Failure

If your patient has acute liver failure with elevated ICP, the 2020 Anaesthesia guidelines specifically recommend:

• Target sodium level at 140-145 mmol/L (slightly lower than general TBI recommendations) 1
• Infusion of hypertonic saline to maintain serum sodium at 145-155 mmol/L significantly decreased ICP in the Murphy et al. RCT 1
• Corrections should not exceed 10 mmol/L per 24 hours 1
• A serum sodium level above 150 mmol/L is deleterious and should be avoided in this population 1

Agents NOT Recommended

Do not use the following for ICP management in this acute setting:

• Lactulose or rifaximin—not recommended for lowering ammonia levels in acute liver failure with elevated ICP 1
• Acetazolamida—not effective for acute ICP management; reserved for idiopathic intracranial hypertension 6
• Induced moderate hypothermia (<34°C)—a 2023 multicenter RCT found no benefit (RR 1.31,95% CI 0.53-3.2 for sustained ICP elevation) 1