Thu21October0907PM 1

True / False

Is freely filtered by the glomerulus Incorrect answer selected

May crystallise at room temperature Correct

Causes a decrease in cerebral blood flow Correct

Acts as a 'free radical scavenger' Incorrect answer selected

Is reabsorbed at the distal convoluted tubule Correct

Explanation

Mannitol is freely filtered through the glmerulus and is not re-absorbed. Alongside its diuretic effect, mannitol is also a 'free radical scavenger'.

Mannitol reduces ICP in two ways. Initially, fluid expansion reduces blood viscosity and increases cardiac output, resulting in an improvement in cerebral blood flow. This process is enhanced by the development of an osmotic gradient.

Provided that the blood brain barrier is intact, mannitol shifts water from the cerebral extracellular space to the vasculature and hence reduces cerebral oedema.

Reference:

Shawkat H, Westwood MM, Mortimer A. Mannitol: a review of its clinical uses. Contin Educ Anaesth Crit Care Pain. 2012;12:82-85.

Answer Statistics

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Average score: 74.27%

Times answered: 234