Mannitol lowers intracranial pressure by which mechanism?

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Multiple Choice

Mannitol lowers intracranial pressure by which mechanism?

Understanding how osmotic therapies affect intracranial pressure is key. Mannitol increases the osmolality of the blood, and because it does not rapidly cross an intact blood–brain barrier, water from brain tissue is drawn into the vascular space to equalize the osmotic gradient. This shifts fluid out of swollen brain tissue, reducing cerebral edema and lowering intracranial pressure. The subsequent diuresis helps remove the excess water. This mechanism would not lower ICP by increasing CSF production, decreasing blood pressure, or increasing brain edema, so osmotic drawing of water from the brain is the correct concept.

Understanding how osmotic therapies affect intracranial pressure is key. Mannitol increases the osmolality of the blood, and because it does not rapidly cross an intact blood–brain barrier, water from brain tissue is drawn into the vascular space to equalize the osmotic gradient. This shifts fluid out of swollen brain tissue, reducing cerebral edema and lowering intracranial pressure. The subsequent diuresis helps remove the excess water. This mechanism would not lower ICP by increasing CSF production, decreasing blood pressure, or increasing brain edema, so osmotic drawing of water from the brain is the correct concept.

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