From the Guidelines
Hypertonic saline is indicated for the treatment of severe symptomatic hyponatremia, particularly when sodium levels are below 120-125 mEq/L and accompanied by neurological symptoms such as seizures, altered mental status, or coma, as stated in the most recent guidelines 1. The primary goal is to rapidly increase serum sodium by 4-6 mEq/L to prevent cerebral edema and neurological complications.
- Typically, 3% hypertonic saline is administered at an initial rate of 1-2 mL/kg/hour, with frequent monitoring of serum sodium levels (every 2-4 hours) to avoid overly rapid correction.
- The correction rate should not exceed 8-10 mEq/L in 24 hours or 18 mEq/L in 48 hours to prevent osmotic demyelination syndrome, as recommended by recent studies 1.
- Hypertonic saline is also indicated in hypovolemic hyponatremia with hemodynamic instability, though isotonic saline may be sufficient in milder cases.
- For chronic hyponatremia (>48 hours), correction should be even more cautious, limiting to 4-6 mEq/L per 24 hours, as suggested by the American Association for the Study of Liver Diseases 1. The physiological basis for hypertonic saline's effectiveness is its ability to rapidly increase serum osmolality, drawing water from intracellular spaces (particularly brain cells) into the extracellular fluid, thereby reducing cerebral edema and alleviating neurological symptoms.
- The use of hypertonic saline is reserved for short-term treatment of patients with symptomatic or severe hyponatremia or those with imminent liver transplant, as stated in recent guidelines 1.
- Severe hyponatremia (<120 mEq/L) at the time of liver transplant increases the risk of osmotic demyelination syndrome, and multidisciplinary coordinated care may mitigate this risk, as noted in recent studies 1.
From the Research
Indications for Hypertonic Saline in Hyponatremia
The use of hypertonic saline in treating hyponatremia is indicated in certain scenarios, including:
- Patients with hyponatremia associated with moderate or severe symptoms to prevent neurological complications 2
- Severe symptomatic hyponatraemia, where hypertonic saline can be used to rapidly correct serum sodium levels 3
- Hyponatremia-induced seizures, where 3% hypertonic saline can be used in combination with anti-convulsants to abort seizures and correct serum sodium levels 4
- Symptomatically hyponatremic patients, most of whom become acutely hyponatremic, where hypertonic saline can be used to rapidly correct serum sodium levels 5
Key Considerations
When using hypertonic saline to treat hyponatremia, the following considerations are important:
- Hypertonic saline should be reserved for patients with symptoms possibly attributable to hyponatremia 5
- A target level for the serum sodium should be determined and a time-course for correction set 5
- The infusion should be started promptly and monitored frequently for the effect on the serum sodium level and patient symptoms 5
- Careful monitoring is necessary to prevent overcorrection, which can lead to neurological complications such as central pontine myelinolysis (CPM) 3, 4