Which result would best show mannitol was effective in decreasing intracranial pressure?

Which result would best show mannitol was effective in decreasing intracranial pressure?

• A. Urine output increases
• B. Pupils are 8 mm and nonreactive
• C. Systolic blood pressure remains 150 mm Hg
• D. BUN and creatinine levels return to normal

Answer: (A)

Mannitol lowers intracranial pressure by acting as an osmotic diuretic: it increases plasma osmolality, pulling water out of swollen brain tissue into the bloodstream, and this excess fluid is then excreted by the kidneys. The clearest sign that this effect is occurring is a sharp rise in urine output, reflecting diuresis and the removal of the brain’s excess fluid. Pupils that are 8 mm and nonreactive suggest brain herniation or severe injury, not improvement in ICP. A systolic blood pressure of 150 mm Hg may indicate a compensatory response to ICP or other issues, not necessarily reduced ICP. Normalizing BUN and creatinine shows kidney function returning toward baseline, which doesn’t directly demonstrate reduced intracranial pressure.

Mannitol lowers intracranial pressure by acting as an osmotic diuretic: it increases plasma osmolality, pulling water out of swollen brain tissue into the bloodstream, and this excess fluid is then excreted by the kidneys. The clearest sign that this effect is occurring is a sharp rise in urine output, reflecting diuresis and the removal of the brain’s excess fluid.

Pupils that are 8 mm and nonreactive suggest brain herniation or severe injury, not improvement in ICP. A systolic blood pressure of 150 mm Hg may indicate a compensatory response to ICP or other issues, not necessarily reduced ICP. Normalizing BUN and creatinine shows kidney function returning toward baseline, which doesn’t directly demonstrate reduced intracranial pressure.