Increased brain bulk may be problematic during brain surgery for tumors because it may limit
surgical exposure and access to the surgical site. Mannitol, an osmotic diuretic, is commonly
given to alleviate brain bulk, and sometimes furosemide in a small dose is added if mannitol
alone is insufficient. It is unclear if adding this furosemide truly helps to diminish brain
bulk, and it is possible that furosemide may cause too much diuresis, leading to dehydration
and its side effects (e.g., low blood pressure). Our purpose is to investigate what the
effects of furosemide are in the setting of brain surgery for tumors, specifically with
regards to decreasing brain bulk and/or causing dehydration.
Study Hypothesis: The addition of furosemide to mannitol will result in improved brain
relaxation in human subjects undergoing craniotomy for brain tumor resection than that seen
with mannitol alone. However, the combination of mannitol and furosemide will also lead to
more significant intravascular volume depletion than that seen with mannitol alone.