Effect of mannitol on cerebral blood volume in patients with head injury

Michael N. Diringer, Michael T. Scalfani, Allyson R. Zazulia, Tom O. Videen, Rajat Dhar, William J. Powers

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


BACKGROUND: Mannitol has traditionally been the mainstay of medical therapy for intracranial hypertension in patients with head injury. We previously demonstrated that mannitol reduces brain volume in patients with cerebral edema, although whether this occurs because of a reduction in brain water, blood volume, or both remains poorly understood. OBJECTIVE: To test the hypothesis that mannitol acts by lowering blood viscosity leading to reflex vasoconstriction and a fall in cerebral blood volume (CBV). METHODS: We used O positron emission tomography to study 6 patients with traumatic brain injuries requiring treatment for intracranial hypertension. Cerebral blood flow (CBF), CBV, and cerebral metabolic rate for oxygen (CMRO2) were measured before and 1 hour after administration of 1.0 g/kg 20% mannitol. RESULTS: CBV rose from 4.1 ± 0.4 to 4.2 ± 0.2 mL/100 g (P =.3), while intracranial pressure fell from 21.5± 4.9 to 13.7 ± 5.1 mm Hg (P <.003) after mannitol. Blood pressure, PaCO2, oxygen content, CBF, and CMRO2 did not change. CONCLUSION: A single bolus of 1 g/kg of 20% mannitol does not acutely lower CBV. Another mechanism, such as a reduction in brain water, may better explain mannitol's ability to lower intracranial pressure and reduce mass effect.

Original languageEnglish
Pages (from-to)1215-1218
Number of pages4
Issue number5
StatePublished - May 2012


  • Cerebral blood flow
  • Cerebral blood volume
  • Mannitol
  • Osmotic


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