Concern for volume depletion and electrolyte abnormalities in furosemide arm.

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.

Rating of brain relaxation will be on a 4-point scale:

0 = brain very relaxed under dura, acceptable

1. = brain adequately relaxed under dura, acceptable
2. = brain slightly tense under dura, acceptable
3. = brain very tense under bulging dura, unacceptable

Inclusion Criteria:

• Inclusion criteria include:

  • ASA PS I-III
  • Age 18 or older
  • Presenting for elective resection of primary or metastatic supratentorial brain tumor(s)

Exclusion Criteria:

• • ASA PS IV or V

  • Age less than 18
  • Emergency surgery due to severely elevated ICP/impending brainstem herniation
  • Concurrent use of diuretics for any indication
  • Infratentorial/posterior fossa/cerebellar tumor resection
  • Moderate/severe cardiac disease with limitation in contractility as measured by preoperative echocardiogram (EF < 30%)
  • Severe pulmonary hypertension as measured and/or observed by preoperative studies
  • Preoperative use of steroids (within 6 months, including those on standing doses)
  • Pregnancy

Recruitment was stopped at 23 subjects because of concern that the administration of furosemide was producing such a large diuresis that clinically significant and potentially unsafe hypovolemia and electrolyte abnormalities were developing.