Hyperosmolar Therapy in Neurotrauma

Purpose: To reduce elevated intracranial pressure (ICP) and mitigate secondary brain injury in patients with traumatic brain injury (TBI), intracerebral hemorrhage, or other causes of cerebral edema.

Sustained ICP > 20–22 mmHg despite sedation and positioning
Clinical signs of herniation (e.g., unilateral mydriasis, decerebrate posturing)
Radiologic evidence of cerebral edema, midline shift, or compressed ventricles

Creates an osmotic gradient across the blood-brain barrier (BBB), drawing water from brain parenchyma into the intravascular space
Reduces cerebral blood volume via plasma expansion and decreased blood viscosity

Main Agents

Concentration: 20% (0.25–1.0 g/kg IV bolus)
Onset: 15–30 min | Duration: 2–6 h
Requires intact BBB to be effective
Monitor serum osmolality (< 320 mOsm/kg) and renal function
Risk: hypovolemia, renal failure, rebound ICP increase with repeated doses

Available concentrations: 3%, 7.5%, 23.4%
Dosing examples:
1. 3%: 250 mL over 20–30 min
2. 7.5%: 100–150 mL bolus
3. 23.4%: 30 mL bolus over 10–15 min via central line only
Preferred in patients with hypotension or polyuria
Monitor serum sodium (target: 145–155 mmol/L) and chloride
Can be used as continuous infusion (e.g., 3% NaCl at 30–70 mL/h)

Feature	Mannitol	Hypertonic Saline
Volume status	Diuretic effect (↓ volume)	Volume expansion (↑ MAP)
Use with hypotension	Contraindicated	Preferred
Risk of rebound ICP	Higher	Lower
Monitoring	Osmolality, Cr	Na+, Cl−, fluid balance

Frequent ICP monitoring (EVD or intraparenchymal probe)
Serum sodium/osmolality every 4–6 h
Renal function and urine output
Avoid prolonged or aggressive correction (>12 mEq/L/24h in chronic hyponatremia)

Combine with other ICP-lowering strategies: sedation, head elevation, normocapnia
Avoid hypotonic fluids (e.g., D5W, 0.45% NaCl)
HTS may be preferred in polytrauma or hypotensive patients
Do not use empirically without signs of raised ICP