Comparison of Equiosmolar Doses of Mannitol 20% Versus Hypertonic Saline 7.5% Infusion in the Reduction of Brain Bulk During Elective Craniotomies for Supratentorial Brain Tumor Resection
Raised intracranial pressure occurs following an expansion of an intracranial mass e.g.
hematoma or brain tumor and if left untreated, can lead to brain ischemia, stroke and death.
Strategies for reducing raised intracranial pressure include hyperventilation, use of a
hyperosmolar agent and the evacuation of the intracranial mass.
The two hypertonic solutions most commonly used are Mannitol 20% and Hypertonic Saline 7.5%.
During elective neurosurgical removal of a brain tumour, the anesthesiologist needs to
reduce intracranial pressure and provide good operating brain conditions to avoid brain
Currently, Mannitol 20% is routinely used intra-operatively in these patients to reduce
brain bulk and intracranial pressure and to improve brain operating conditions.
However, Mannitol itself can cause secondary effects that can be deleterious to the
neurological patient. Mannitol causes a diuresis which may lead to systemic hypovolemia and
hypotension, and adverse changes in serum and urinary sodium, potassium and osmolarity.
Experience with Hypertonic saline 7.5%, has been mainly in brain injured patients either in
the Emergency Dept or in the Intensive care setting. There is growing evidence that
Hypertonic saline 7.5% is just as effective as Mannitol 20% in reducing raised intracranial
pressure, especially in traumatic brain injury and it has become a widely accepted form of
treatment. One of the advantages of Hypertonic saline is that it does not cause a diuresis
and therefore less likely to cause hypotension and hypovolemia. While transient
hypernatremia has been observed after the administration of hypertonic saline, there have
been no clinical consequences.
Unfortunately there have been only two studies which compared the effectiveness of
Hypertonic saline and Mannitol during elective brain surgery. One of them, Gemma et al,
failed to demonstrate any difference in the reduction of brain bulk between Mannitol and
Hypertonic saline. However the 2 solutions used had different osmolarities and this may have
had a confounding effect on the results. In the other study (published in Polish), the
authors found a 20% reduction in brain bulk in favour of hypertonic saline. In view of
these two opposing findings, we feel that another investigation is warranted.
Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double-Blind, Primary Purpose: Treatment
Surgeon’s assessment of brain bulk.
Rosemary A Craen, MD
Associate Proffesor UWO
Canada: Health Canada