What is the emergency treatment for severe hyponatremia?

Emergency Treatment for Severe Hyponatremia

For severe symptomatic hyponatremia, administer 3% hypertonic saline with an initial goal to correct serum sodium by 6 mmol/L over 6 hours or until severe symptoms resolve, with total correction not exceeding 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome. 1, 2

Initial Assessment and Management

• Severe symptomatic hyponatremia (characterized by mental status changes, seizures, or coma) requires immediate treatment in an intensive care unit setting 1, 2
• Treatment approach depends on symptom severity, acuity of onset, and volume status of the patient 2, 3
• For patients with severe symptoms, administer 3% hypertonic saline and monitor serum sodium levels every 2 hours 1
• Target correction of 6 mmol/L over 6 hours or until severe symptoms improve 1, 2

Rate of Correction Guidelines

• Total correction should not exceed 8 mmol/L in the first 24 hours to prevent osmotic demyelination syndrome 1, 2
• If 6 mmol/L is corrected in the first 6 hours, sodium should not be increased more than 2 mmol/L in the following 18 hours 1
• Rapid correction at a rate exceeding 1 mmol/L/hour should be reserved only for severely symptomatic and/or acute hyponatremia (developed within 48 hours) 1, 2
• Chronic hyponatremia should never be rapidly corrected due to risk of osmotic demyelination 1, 2

Treatment Based on Etiology

For Cerebral Salt Wasting (CSW):

• Treat with hypertonic saline and fludrocortisone in the ICU setting 1
• Volume repletion with normal saline is the primary approach 2
• Avoid fluid restriction as it can worsen outcomes, particularly in subarachnoid hemorrhage patients 2

For Syndrome of Inappropriate Antidiuretic Hormone (SIADH):

• For severe symptoms, use hypertonic saline 1
• For mild symptoms, fluid restriction to 1 L/day is the cornerstone of treatment 1, 2
• Consider adding NaCl 100 mEq orally three times daily if needed 2

Monitoring and Safety Considerations

• Calculate sodium deficit using the formula: Desired increase in Na (mEq/L) × (0.5 × ideal body weight in kg) 1, 2
• Monitor serum sodium every 2 hours in severely symptomatic patients 1
• Watch for signs of overcorrection, especially in severely symptomatic patients 2
• If symptoms resolve during treatment, switch to less aggressive protocols for mild symptoms or asymptomatic hyponatremia 1

Special Considerations

• In neurosurgical patients with subarachnoid hemorrhage, treat even for serum sodium levels of 131-135 mmol/L due to risk of vasospasm 1
• For patients with cirrhosis and hypervolemic hyponatremia, fluid restriction to 1-1.5 L/day is recommended 2
• A retrospective study showed increased mortality in patients with serum Na <115 mmol/L who had slower correction of hyponatremia 1

Common Pitfalls to Avoid

• Overly rapid correction of chronic hyponatremia can lead to osmotic demyelination syndrome, which can result in parkinsonism, quadriparesis, or death 3
• Failure to recognize and treat severe symptomatic hyponatremia promptly can lead to cerebral edema and increased mortality 3, 4
• Treating without identifying the underlying cause may lead to recurrence or inadequate management 3, 5
• Not distinguishing between acute and chronic hyponatremia can lead to inappropriate correction rates 6