What is the treatment for severe symptomatic hyponatremia with hypertonic (hyperosmolar) saline?

From the Guidelines

For severe symptomatic hyponatremia, administer 100 mL of 3% hypertonic saline as an IV bolus over 10 minutes, with a goal to raise serum sodium by 5 mmol/L in the first hour and limit the increase to 8-10 mmol/L every 24 hours thereafter, as recommended by the most recent guidelines 1. The use of hypertonic saline is reserved for short-term treatment of patients with symptomatic or severe hyponatremia, and the goal rate of increase of serum sodium is 4-6 mEq/L per 24-hour period, not to exceed 8 mEq/L per 24-hour period to ameliorate the risk of osmotic demyelination syndrome 1. The treatment should be individualized, and close monitoring of serum sodium levels every 2-4 hours during treatment is essential to avoid overly rapid correction. Symptoms requiring urgent treatment include seizures, severe confusion, coma, or respiratory distress. The hypertonic saline works by rapidly increasing extracellular osmolality, drawing water out of brain cells and reducing cerebral edema, which is the primary cause of severe neurological symptoms in acute hyponatremia. It is also important to note that the use of hypertonic sodium chloride administration may improve natremia but enhances volume overload and worsens the amount of ascites and oedema, and therefore should be limited to severely symptomatic hyponatremia, as defined by life-threatening manifestations 1. In patients with cirrhosis, severe hyponatremia at the time of liver transplant increases the risk of osmotic demyelination syndrome, and multidisciplinary coordinated care may mitigate this risk 1. The most recent guidelines recommend that hypertonic sodium chloride administration should be reserved for those who are severely symptomatic with acute hyponatraemia, and serum sodium should be slowly corrected 1.

Some key points to consider when treating severe symptomatic hyponatremia include:

• The use of 3% hypertonic saline as an initial treatment
• The goal of raising serum sodium by 5 mmol/L in the first hour and limiting the increase to 8-10 mmol/L every 24 hours thereafter
• Close monitoring of serum sodium levels every 2-4 hours during treatment
• Individualized treatment to avoid overly rapid correction
• The importance of considering the underlying cause of hyponatremia and addressing it accordingly
• The potential risks and benefits of using hypertonic saline, including the risk of osmotic demyelination syndrome and the potential for worsening volume overload and ascites.

Overall, the treatment of severe symptomatic hyponatremia requires a careful and individualized approach, taking into account the underlying cause of the condition, the severity of symptoms, and the potential risks and benefits of treatment, as recommended by the most recent guidelines 1.

From the Research

Severe Hyponatremia Treatment

• Severe hyponatremia may be chronic (days) or acute (hours), symptomatic or asymptomatic 2.
• The treatment of severe chronic symptomatic hyponatremia should be halted once a mildly hyponatremic range of the serum sodium concentration has been reached (approximately 125 to 130 mM/liter) 2.
• Severe symptomatic acute hyponatremia should be treated promptly and rapidly, using hypertonic saline, to initially reach a mildly hyponatremic level 2.

Hypertonic Saline Usage

• Hypertonic saline (3%) can be used to treat acute (<48 hours) hyponatremia, usually observed in the postoperative period, to prevent seizures and respiratory arrest 3.
• The European guidelines recommend bolus-wise administration of 150 mL of 3% hypertonic saline for the treatment of symptomatic hyponatremia 4.
• Reducing bolus-volume and reevaluation before repeating bolus infusion might prevent overcorrection in severely symptomatic patients 4.

Correction Rate

• The rate of correction of severe chronic symptomatic hyponatremia should be no more than 0.5 mM per liter per hour 2.
• For patients with chronic (>48-72 hours) symptomatic hyponatremia, correction must be rapid during the first few hours (to decrease brain edema) followed by a slow correction limited to 10 mmol/L over 24 hours to avoid the development of osmotic demyelinating syndrome 3.
• The daily increase in serum sodium should be limited to less than 8-10 mmol/liter to prevent osmotic demyelination 5.

Monitoring and Prevention

• Frequent measurements of serum sodium during the correction phase are mandatory to avoid overcorrection 3.
• Close monitoring of the serum sodium is indicated initially, and if necessary, correction must be stopped and diuresis interrupted with dDAVP 6.
• In patients overly corrected (delta SNa > 15 mEq/1/24 h), the risk of myelinolysis could be greatly reduced by rapidly decreasing the serum sodium through hypotonic fluids administration and dDAVP 6.