Osmotic therapy is frequently used to treat intracranial hypertension, cerebral edema and tissue shifts due to 
intracranial mass lesions. Some patients do not respond to sustained mannitol administration with the expected rise in serum osmolality, and this may correlate with lack of therapeutic efficacy, according to the article in the PubMed Journals on October 2008.
In normal brain with an intact blood-brain-barrier (BBB), however, mannitol is confined to the intravascular compartment; this creates an osmotic gradient, which results in movement of water out of the intracellular and interstitial compartments of the brain into the vasculature. This osmotic effect reduces net intracranial volume and is the most widely accepted mechanism accounting for mannitol’s ability to lower Intracranial Pressure, accordingly.
But there were terms called “mannitol resistant” where mannitol is ineffective at controlling intracranial hypertension. In these patients, manifest a failure of their serum sodium and osmolality to rise as expected. The following article described this lack of osmotic response might, in part, explain cases of resistance to mannitol therapy.
Salah G. Keyrouz, M.D.,from Neurology/Neurosurgery Intensive Care Unit, Department of Neurology and Neurological Surgery, Washington University, and his colleagues performed a reviewed data on patients who received mannitol therapy in order to define the frequency with which osmolality fails to rise with mannitol administration, and to identify factors associated with this lack of an osmotic response.
Find completely about Effectiveness of Osmotic Therapy in The Reduction of Intracranial Pressure – Frequency, and Factors Associated here (source: pubmedcentral.nih.gov, image source: manitol.org). If you troubled in downloading this file, you may download through this link.
