Neurocritical Care

Mannitol

Hypertonic Saline

Typical dose

0.5–1 g/kg over 15 min (0.2-micron filter)

Up to 1.6 g/kg if acute herniation

3%: 2.5–5 mL/kg over 15 min

7.5%: 1–2 mL/kg over 15 min

23.4%: 30 mL over 15 min (may infuse

over 5–10 minutes in acute herniation)

Monitoring values

Serum: Osmolality, BMP (Na, K, SCr,

BUN, glucose), osmolar gap

Urine: Urinary output

Serum: Osmolality, Na, SCr, K

Urine: Urinary output

Adverse effects

Hyper/hyponatremia

Hypokalemia

Renal failure

Hypovolemia

Rebound cerebral edema (?)

Hypernatremia

Hypokalemia

Hyperchloremic acidosis

Renal failure

Osmotic demyelination syndrome (?)

O’Brien SK, Koehl JL, Demers LB, Hayes BD, Barra ME. Safety and tolerability of 23.4% hypertonic saline administered over 2 to 5 minutes for the treatment of

cerebral herniation and intracranial pressure elevation. Neurocrit Care. 2023;38(2):312-319. https://doi.org/10.1007/s12028-022-01604-1

Metabolic acidosis may occur after several hypertonic saline doses as the result of hyperchloremia.

In patients with acidemia, which complicates ventilator management or other aspects of care,

a combination of sodium chloride and sodium acetate may be considered to maintain the

Sodium bicarbonate 8.4% may also be considered for acute ICP elevations when other osmotherapy

options are not immediately available, such as in patient care areas that do not typically care for

neurologic ICU patients or patients with a TBI (Neurocrit Care 2010;13:24-8).

mOsm/L when using mannitol.

Theory was that serum osmolality values greater than 320 were associated with renal dysfunction.

Osmolar gap appears to be a more appropriate and accurate method of evaluating renal dysfunction

risk with mannitol.

Approximates the mannitol concentration

many centers choose to target a goal osmolar gap less than 20–30 mOsm/kg prior to re-dosing

mannitol.

Calculation of osmolar gap (Box 2)

Box 2. Calculation of Osmolar Gap

Osmolar gap = measured osmolality − estimated osmolality

Osmolar gap = measured osmolality − [(2 × Na) + (BUN/2.8) + (glucose/18)]

agitation, decreased cerebral metabolic rate (CMRO2)

Propofol is typically the preferred sedative – Quick onset, short acting, less accumulation with prolonged

duration

Patients with a TBI (and other neurologic injuries) require frequent, accurate neurologic

examinations to evaluate the evolution of the neurologic injury.

Hypotension risk may be harmful in specific patient types (e.g., aneurysmal SAH/vasospasm, TBI,

SCI).