How to manage severe hyponatremia with 0.45% sodium chloride infusion?

Management of 0.45% Sodium Chloride Infusion

Critical Assessment: This is NOT Appropriate for Severe Hyponatremia

0.45% sodium chloride (half-normal saline) at 60 mL/hr should NOT be used for severe hyponatremia and may actually worsen the condition. This hypotonic solution contains only 77 mEq/L of sodium and will provide excessive free water, potentially lowering serum sodium further 1.

When 0.45% NaCl IS Appropriate

Hyperglycemic Crisis Management

• 0.45% NaCl is indicated when corrected serum sodium is normal or elevated in diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS) 1
• Infuse at 4-14 mL/kg/hr once initial volume resuscitation with 0.9% NaCl is complete 1
• Correct serum sodium for hyperglycemia: add 1.6 mEq to sodium value for each 100 mg/dL glucose above 100 mg/dL 1
• Once serum glucose reaches 250 mg/dL in DKA, switch to 5% dextrose with 0.45-0.75% NaCl 1

Hypernatremia Correction

• 0.45% NaCl is appropriate for moderate hypernatremia requiring gradual correction 2
• Provides both free water and some sodium replacement 2
• Correction should occur over 48-72 hours to prevent cerebral edema 2

What to Use Instead for Hyponatremia

For Severe Symptomatic Hyponatremia (Na <120 mEq/L with neurologic symptoms)

• Administer 3% hypertonic saline immediately 2, 3, 4
• Give 100-150 mL IV bolus over 10 minutes, repeatable up to 3 times 4
• Target: increase sodium by 6 mEq/L over first 6 hours or until symptoms resolve 2, 3
• Maximum correction: 8 mEq/L in 24 hours to prevent osmotic demyelination syndrome 2, 5, 3
• Monitor serum sodium every 2 hours during active correction 2

For Hypovolemic Hyponatremia

• Use 0.9% normal saline (154 mEq/L sodium) for volume repletion 1
• Appropriate when urine sodium <30 mmol/L suggests volume depletion 2
• Discontinue diuretics immediately 1

For Hypervolemic Hyponatremia (cirrhosis, heart failure)

• Implement fluid restriction to 1-1.5 L/day for sodium <125 mmol/L 1, 2
• Temporarily discontinue diuretics 1
• Consider albumin infusion in cirrhotic patients 1
• Avoid hypertonic saline unless life-threatening symptoms present 1

For Euvolemic Hyponatremia (SIADH)

• Fluid restriction to 1 L/day is cornerstone of treatment 2
• Add oral sodium chloride 100 mEq three times daily if no response to fluid restriction 2
• Consider vaptans (tolvaptan 15 mg daily) for resistant cases 2, 4

Critical Safety Considerations

Correction Rate Limits

• Standard patients: 4-8 mEq/L per day, maximum 10-12 mEq/L in 24 hours 2
• High-risk patients (cirrhosis, alcoholism, malnutrition): 4-6 mEq/L per day, maximum 8 mEq/L in 24 hours 2, 5
• Rapid correction >20 mEq/L in first 24 hours significantly associated with mortality or osmotic demyelination syndrome 5

Monitoring Requirements

• Severe symptoms: check sodium every 2 hours initially 2
• Mild symptoms: check sodium every 4 hours 2
• Watch for osmotic demyelination syndrome signs (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically 2-7 days post-correction 2

If Overcorrection Occurs

• Immediately discontinue current fluids and switch to D5W 2
• Consider desmopressin to slow or reverse rapid sodium rise 2
• Target: bring total 24-hour correction to ≤8 mEq/L from starting point 2

Common Pitfalls to Avoid

• Using hypotonic fluids (0.45% NaCl) for hyponatremia will worsen the condition 1, 2
• Failing to assess volume status before selecting fluid type 2
• Correcting chronic hyponatremia too rapidly (>8 mEq/L/24 hours) 2, 5
• Using normal saline for SIADH (will worsen hyponatremia) 2
• Using fluid restriction for cerebral salt wasting (worsens outcomes) 2