Can more than 3 boluses of 3% (three percent) saline be administered over 24 hours?

Administration of 3% Saline Boluses for Raised Intracranial Pressure

More than 3 boluses of 3% saline can be administered over 24 hours when clinically indicated, but requires careful monitoring of serum sodium levels to prevent overcorrection and associated complications.

Dosing Guidelines for 3% Saline

• For acute management of elevated intracranial pressure (ICP), the standard dose is 5 mL/kg of 3% hypertonic saline administered over 15-20 minutes per bolus 1
• Maximum effect of hypertonic saline is observed after 10-15 minutes and lasts for 2-4 hours, which informs the timing between boluses 1
• In severe cases of hyponatremia with neurological symptoms, up to three 100 mL boluses of 3% saline spaced at 10-minute intervals are initially recommended 2

Monitoring Requirements When Exceeding 3 Boluses

• Serum sodium levels must be measured within 6 hours of bolus administration 1
• Additional boluses should not be administered until serum sodium concentration is confirmed to be <155 mmol/L 1
• Continuous monitoring of ICP is essential during therapy, especially when multiple boluses are required 1
• Urine output should be closely monitored as diuresis correlates with the degree of sodium overcorrection (r = 0.6, P < 0.01) 3

Safety Considerations for Multiple Boluses

• The goal is to increase serum sodium by 6-8 mmol/L in 24 hours, 12-14 mmol/L in 48 hours, and 14-16 mmol/L in 72 hours 4
• Overcorrection (defined as >10 mmol/L in 24 hours, >18 mmol/L in 48 hours, or >20 mmol/L in 72 hours) risks iatrogenic brain damage 4
• Administration of desmopressin may be necessary to terminate unwanted water diuresis and prevent overcorrection when multiple boluses are given 4
• The risk of overcorrection is higher in patients with severe symptoms (38%) compared to those with moderate symptoms (6%) 3

Clinical Evidence Supporting Multiple Boluses

• Case reports document successful use of large-volume infusion (up to 950 mL) of 3% saline for treatment of exercise-associated hyponatremic encephalopathy without adverse events 5
• Recent research shows that 250 mL boluses of 3% saline are more effective than 100 mL boluses for treating severe hyponatremia (52% vs 32% achieving ≥5 mmol/L rise within 4 hours) without increasing overcorrection risk 6
• For syndrome of inappropriate antidiuresis (SIAD), bolus infusion of 3% saline causes more rapid elevation of plasma sodium at 6 hours compared to continuous infusion [median 6 vs 3 mmol/L, P<0.0001] 7

Algorithm for Administration Beyond 3 Boluses

1. Administer initial 3 boluses as per standard protocol (5 mL/kg or 100 mL of 3% saline) 1, 2
2. Check serum sodium level after the third bolus 1
3. If symptoms persist and serum sodium is <155 mmol/L, additional boluses can be given 1
4. For each additional bolus beyond the third:
   • Monitor serum sodium before administration 1
   • Check urine output (high output may signal impending overcorrection) 3
   • Consider reducing bolus volume for subsequent doses 3
   • Have desmopressin available to prevent overcorrection if water diuresis develops 4

Special Considerations

• Patients receiving a third or more saline bolus have greater need for dextrose/dDAVP to prevent overcorrection (OR 24; P = 0.006) 7
• For patients with cerebral salt wasting, fluid restriction is contraindicated as it may increase the risk of cerebral infarction 2
• No evidence of osmotic demyelination syndrome has been reported with proper monitoring despite multiple boluses 1, 7, 6