Is D5W IV at 100 ml/hr x 1 Liter and recheck an appropriate initial treatment for hypernatremia with a serum sodium level of 164 mmol/L?

Hypernatremia Management with Serum Sodium 164 mmol/L

D5W at 100 ml/hr for 1 liter is too slow and insufficient for correcting severe hypernatremia with a serum sodium of 164 mmol/L—you need a more aggressive approach with hypotonic fluids at higher rates, targeting a correction of 10-15 mmol/L per 24 hours while avoiding overly rapid correction that could cause cerebral edema. 1

Recommended Correction Strategy

Target a reduction of 10-15 mmol/L per 24 hours to safely lower the sodium from 164 mmol/L toward normal range. 1 This rate balances the need for timely correction against the risk of cerebral edema from overly rapid shifts. 2

Fluid Selection and Rate

• Use D5W (5% dextrose in water) as the primary hypotonic fluid for free water replacement in severe hypernatremia. 1
• Calculate the free water deficit to determine total volume needed: Free water deficit = 0.6 × body weight (kg) × [(current Na/140) - 1]. 1
• Infusion rates of 100-150 ml/hr are typically needed for adults with severe hypernatremia, which is faster than the proposed 100 ml/hr. 1
• Recheck sodium levels every 4-6 hours initially rather than waiting until 1 liter is complete, as this allows for real-time adjustment of the correction rate. 1, 3

Critical Safety Considerations

Avoid correcting faster than 48-72 hours for severe hypernatremia, as more rapid correction has been associated with increased risk of pontine myelinolysis and cerebral edema. 1, 2 The proposed plan of only 1 liter before rechecking may result in inadequate correction over the first 10 hours.

Monitoring Protocol

• Check serum sodium every 4-6 hours during active correction to ensure you're hitting the target rate of 10-15 mmol/L per day. 1, 3
• Monitor for signs of cerebral edema: altered mental status, seizures, or worsening neurologic function during correction. 2
• Adjust infusion rate based on sodium response: if correction is too rapid (>15 mmol/L in 24 hours), slow the rate; if too slow (<10 mmol/L in 24 hours), increase the rate. 1

Special Populations Requiring Caution

Patients with chronic hypernatremia (>48 hours duration) require slower correction to prevent cerebral edema, as brain cells have adapted to the hyperosmolar state. 2, 4 The elderly and those with underlying neurologic conditions are at highest risk for complications. 2

Alternative Hypotonic Fluids

• 0.45% NaCl (half-normal saline) can be used for moderate hypernatremia, providing 77 mEq/L sodium with osmolarity ~154 mOsm/L. 1
• 0.18% NaCl (quarter-normal saline) provides more aggressive free water replacement with ~31 mEq/L sodium for severe cases. 1
• Avoid isotonic fluids (0.9% NaCl) entirely, as these will worsen hypernatremia by providing inadequate free water. 1, 5

Common Pitfalls to Avoid

Do not wait until 1 liter is infused before rechecking sodium—this 10-hour delay without monitoring could result in either inadequate correction or unexpected overcorrection if the patient has impaired renal function. 3 Patients with renal concentrating defects require ongoing hypotonic fluid administration to match excessive free water losses. 1

The mortality rate for hypernatremic dehydration is the highest among all electrolyte disorders, primarily due to CNS dysfunction, making aggressive but controlled correction essential. 2