Hypertonic Saline 3%

How it works

It raises serum osmolality, creating an osmotic gradient that draws water out of brain tissue across an intact blood-brain barrier, reducing cerebral oedema and intracranial pressure.

Prescribing in practice

• Correct sodium too rapidly and you risk osmotic demyelination syndrome, so monitor serum sodium frequently and limit the rate of rise, particularly in chronic hyponatraemia.
• Concentrated solutions are an irritant and are best given via central venous access where feasible, with close attention to the infusion site.
• Use with caution in cardiac failure and volume overload, as the sodium load can precipitate pulmonary oedema.

Monitoring

Monitor serum sodium and osmolality regularly during therapy, alongside fluid balance and neurological status.

Counselling the patient

• Explain to the team that frequent blood tests are needed to control the speed of sodium correction.
• Report any new confusion, weakness or swallowing difficulty promptly.

Evidence & guidelines

Hypertonic saline is an established osmotherapy option for raised intracranial pressure and symptomatic hyponatraemia, with use guided by neurocritical care and electrolyte management consensus.