Recommended Rate for Bolusing 3% Hypertonic Saline
For symptomatic hyponatremia or increased intracranial pressure, 3% hypertonic saline should be administered as 100 mL boluses given over 10 minutes, which can be repeated up to two more times at 10-minute intervals if symptoms persist. 1, 2
Indications and Administration Protocol
For Symptomatic Hyponatremia:
- Initial bolus: 100 mL of 3% saline administered over 10 minutes
- If neurological symptoms persist after 10 minutes, repeat the 100 mL bolus
- Maximum of three 100 mL boluses (total 300 mL) spaced at 10-minute intervals 1
- Goal: Increase serum sodium by 5 mEq/L in the first 1-2 hours to rapidly treat cerebral edema 2
For Increased Intracranial Pressure:
- Bolus doses of 3% hypertonic saline are effective at reducing intracranial pressure 1
- Similar protocol of 100 mL boluses can be used
- Continuous infusions typically utilize 3% hypertonic saline for ongoing ICP management 1
Safety Considerations and Monitoring
- Serum sodium monitoring: Measure within 6 hours of bolus administration 1
- Maximum correction targets:
- First 1-2 hours: Not to exceed 5 mEq/L increase
- First 24 hours: Not to exceed 10 mEq/L increase
- First 48 hours: Not to exceed 15-20 mEq/L increase 2
- Re-administration threshold: Do not repeat boluses if serum sodium is ≥155 mmol/L 1
Evidence on Efficacy and Safety
Bolus administration of 3% saline has been shown to be more effective than continuous infusion for rapid correction of symptomatic hyponatremia:
- Bolus therapy produces faster initial elevation of sodium at 6 hours (median 6 mmol/L vs 3 mmol/L with continuous infusion) 3
- Quicker improvement in Glasgow Coma Scale scores with bolus therapy 3
- More consistent sodium increase with bolus therapy compared to conventional treatments 4
Recent evidence suggests that a 250 mL bolus may be more effective than 100 mL (52% vs 32% achieving ≥5 mmol/L rise within 4 hours) without increasing overcorrection risk 5, but current guidelines still recommend the 100 mL protocol.
Administration Route
- Peripheral IV administration of 3% hypertonic saline is safe and may be preferred over central venous catheter placement 6
- Low complication rates with peripheral administration: infiltration (3.3%), phlebitis (6.2%), erythema (2.3%), edema (1.8%), and venous thrombosis (1%) 6
Common Pitfalls and Caveats
- Risk of overcorrection: More common in patients with severe symptoms (38% vs 6% in moderate symptoms) 4
- Diuresis monitoring: Increased diuresis correlates with sodium overcorrection (r=0.6) 4
- Third bolus risk: Administration of a third saline bolus is associated with greater need for dextrose/dDAVP to prevent overcorrection (OR 24) 3
- Risk factors for cerebral demyelination: Correction >25 mEq/L in 48 hours, correction past 140 mEq/L, chronic liver disease, and hypoxic episodes 2
For patients with increased intracranial pressure, hypertonic saline is effective at reducing ICP (Grade A evidence) but does not improve neurological outcomes (Grade B) or survival (Grade A) 1.