Management of Severe Hypernatremia (Sodium 197 mEq/L) on D5W
Immediate Assessment and Critical Action
You are on the correct initial treatment with D5W, but this patient requires urgent intensive monitoring and a structured correction protocol to prevent fatal complications. A sodium level of 197 mEq/L represents extreme, life-threatening hypernatremia that carries mortality rates exceeding 60% and can cause fatal cardiac arrhythmias including ventricular tachycardia from diffuse QT prolongation 1.
Primary Treatment Strategy
Continue D5W as the primary rehydration fluid because it delivers no renal osmotic load and allows controlled decrease in plasma osmolality 2, 3. This is the preferred hypotonic solution for severe hypernatremia correction 4.
Critical Correction Rate Guidelines
- For chronic hypernatremia (>48 hours): Do NOT exceed 8-10 mEq/L reduction per 24 hours 2, 4
- More rapid correction risks cerebral edema and osmotic demyelination syndrome 4, 5
- For acute hypernatremia (<24 hours): Faster correction may be considered, but extreme caution is still warranted at this sodium level 4
Calculating Free Water Deficit
The free water deficit should be calculated to guide total fluid replacement over 36-48 hours:
- Free water deficit = 0.6 × body weight (kg) × [(current Na/140) - 1]
- Replace this deficit gradually over 36-48 hours while accounting for ongoing losses 3
Intensive Monitoring Protocol
Check serum sodium every 2-4 hours initially to ensure correction rate stays within safe limits 2, 5. This frequent monitoring is non-negotiable at this extreme sodium level.
Monitor for:
- Cardiac arrhythmias: Obtain baseline ECG and monitor for QT prolongation, which can precede fatal ventricular tachycardia 1
- Neurological status changes (confusion, seizures, altered consciousness) 4, 5
- Volume status and urine output 5
- Serum potassium, calcium, and magnesium levels 1
Adjunctive Therapies to Consider
Desmopressin (DDAVP)
If diabetes insipidus is contributing (high urine output with dilute urine despite hypernatremia), administer desmopressin 4, 3. This is particularly important if the patient has:
- Urine osmolality <300 mOsm/kg despite severe hypernatremia
- Polyuria (>3 L/day)
- Recent neurosurgical procedure or pituitary pathology
Free Water via Nasogastric Tube
If the patient can tolerate enteral administration, supplement IV D5W with free water via NG tube 3. This provides additional free water without increasing IV fluid volume and can accelerate safe correction.
Loop Diuretics (Only if Hypervolemic)
If the patient has volume overload (edema, pulmonary congestion, elevated JVP), add furosemide to promote free water excretion 2. However, this must be balanced carefully to avoid worsening dehydration if the patient is hypovolemic.
Special Considerations for Patients on CRRT
If the patient requires continuous renal replacement therapy, infuse calculated amounts of D5W prefilter to prevent overcorrection 6. Standard CRRT replacement fluids are isotonic and will rapidly correct hypernatremia, risking osmotic demyelination syndrome. The D5W rate should be calculated based on prescribed effluent volume to maintain safe sodium correction rates of <8 mEq/L per day 6.
Underlying Cause Investigation
Determine the mechanism while treating:
- Sodium gain: Recent hypertonic saline administration, sodium bicarbonate, or salt ingestion 1
- Free water loss: Diabetes insipidus (central or nephrogenic), osmotic diuresis, insensible losses 4, 5
- Check urine osmolality and urine sodium to differentiate causes 5
Common Pitfalls to Avoid
- Never use isotonic saline (0.9% NaCl) in hypernatremia - it delivers excessive osmotic load requiring 3 liters of urine to excrete the osmotic load from just 1 liter of fluid, worsening hypernatremia 7
- Never correct chronic hypernatremia faster than 8-10 mEq/L per day - this causes cerebral edema 2, 4
- Do not rely on clinical assessment alone - frequent laboratory monitoring is essential 5
- Watch for cardiac complications - extreme hypernatremia can cause fatal arrhythmias even during appropriate correction 1
Expected Timeline
With appropriate D5W therapy and adjunctive measures, expect: