From the Guidelines
Mannitol is not recommended as a first-line treatment for Posterior Reversible Encephalopathy Syndrome (PRES). The primary management of PRES should focus on treating the underlying cause, particularly controlling hypertension and removing any offending agents such as immunosuppressive medications. While mannitol is an osmotic diuretic that can reduce cerebral edema in some neurological conditions, there is limited evidence supporting its routine use in PRES, as seen in the 2022 guideline for the management of patients with spontaneous intracerebral hemorrhage 1.
Key Points to Consider
- In cases of PRES with significant cerebral edema causing increased intracranial pressure, mannitol might be considered at doses of 0.25-1 g/kg IV over 20-30 minutes, but this should be done under close neurological monitoring and only in severe cases with clinical deterioration despite standard management.
- The mechanism of PRES primarily involves endothelial dysfunction and vasogenic edema rather than cytotoxic edema, which is why treating the underlying cause (typically hypertension) is more effective than osmotic agents.
- Blood pressure should be reduced gradually by 25% within the first few hours using IV antihypertensives like nicardipine, labetalol, or clevidipine, as suggested by the management of elevated ICPs in the context of intracerebral hemorrhage 1.
- Most PRES cases resolve within days to weeks with appropriate management of the underlying cause.
Considerations for Mannitol Use
- A study of 20 patients with ICH examined mean flow velocities and pulsatility indices in the middle cerebral artery territory, suggesting that a single bolus of mannitol modifies cerebral hemodynamics, but this is more relevant to ICH than PRES 1.
- Hyperosmolar therapy, including mannitol, is typically administered in 4- to 6-hour intervals, but the duration of transient effects from hyperosmolar therapy in the setting of ICH or PRES is unclear and requires further study 1.
From the FDA Drug Label
HIGHLIGHTS OF PRESCRIBING INFORMATION These highlights do not include all the information needed to use MANNITOL INJECTION safely and effectively. ... Reduction of intracranial pressure and brain mass. ( 1) ... Central Nervous System (CNS) Toxicity: Mannitol may increase cerebral blood flow and the risk of postoperative bleeding in neurosurgical patients.
The use of mannitol in Posterior Reversible Encephalopathy Syndrome (PRES) is not directly addressed in the provided drug labels. However, mannitol is indicated for the reduction of intracranial pressure and may be used in certain neurological conditions.
- Key points:
- Mannitol may increase cerebral blood flow and the risk of postoperative bleeding in neurosurgical patients.
- The labels do not provide specific guidance on the use of mannitol in PRES. Given the lack of direct information on the use of mannitol in PRES, caution should be exercised when considering its use in this context 2, 2.
From the Research
Mannitol in PRES
- There is no direct mention of mannitol in the provided studies 3, 4, 5, 6, 7.
- The treatment strategies for PRES mentioned in the studies include:
- The pathophysiology of PRES is thought to involve disruption of the blood-brain barrier secondary to elevated intracranial pressures or endothelial injury 5.
- The use of mannitol, an osmotic diuretic, is not discussed in the context of PRES treatment in the provided studies.
- It is essential to note that the provided studies focus on the clinical features, diagnosis, and management of PRES, but do not specifically address the role of mannitol in its treatment 3, 4, 5, 6, 7.