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Is the administration of mannitol indicated in patients with confirmed subarachnoid haemorrhage?

Three Part Question

In [patients with confirmed subarachnoid haemorrhage and raised intracranial pressure] does [the administration of mannitol] reduce [morbidity and mortality]?

Clinical Scenario

A 46 year old female presents to the emergency department. Subarchnoid haemorrhage is confirmed by CT. Upon examination there are signs that she has raised intracranial pressure and her clinical condition is deteriorating. You ask one of your colleagues if you should administer mannitol. Neither of you are sure what to do as you have both heard that it is important to maintain cerebral blood pressure fairly high to prevent rebleeding. However, you wonder if the administration of mannitol would help this patient.

Search Strategy

Medline1966 to July Week 1 2006
Embase 1980 to 2006 Week 28
CINAHL 1982 to July Week 2 2006
(humans and english language)
Medline, Embase and CINAHL
[(exp Intracranial Aneurysm/ or exp Subarachnoid Hemorrhage/) OR SAH OR ((subarachnoid adj (haemorrhage$ or hemorrhage or bleed$)).mp.)] AND [(exp Mannitol Dehydrogenase/ or exp Mannitol/ or exp Mannitol Phosphates/) OR ( OR (osmotic OR (] limited to humans and english

Search Outcome

Medline 66 papers
Embase 130 papers
CINALH 0 papers found
Cochrane 10 papers

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses


No papers found were specific to the original question. Papers do exist regarding the use of mannitol intra-operatively for the management of SAH and there is one case report suggesting benefit in 3 patients when combined with dopamine induced hypertension and large volumes of intravascular fluid but there are no trials looking at its use in these patients in the emergency department setting. There are theoretical benefits of giving mannitol to patients with SAH as it has been shown to reduce intracranial pressure and may act as a radical scavenger, decreasing ischaemic injury. There are also known side effects such as cardiopulmonary oedema and rebound cerebral oedema. Cochrane reviews looking at the use of mannitol in patients with raised ICP due to stroke or head injury have not found compelling evidence of benefit although its use is widespread in the UK & US in patients with head injury.

Clinical Bottom Line

There is no evidence of benefit of the administration of mannitol in patients with subarachnoid haemorrhage. However, in patients with signs of rising intracranial pressure and decreasing neurological function the benefits may be felt to outweigh the risks. Neurosurgical advice should be sought and followed.


  1. Brown FD. Hanlon K. Mullan S. Treatment of aneurysmal hemiplegia with dopamine and mannitol. Journal of Neurosurgery 1978; 49(4): 525-9
  2. Graf, CJ et al Cooperative Study of Intracranial Aneurysms and Subarachnoid Hemorrhage: Report on Randomised Treatment Study III Intracranial Surgery Stroke 1974; 174: 557-601
  3. Heuer GG et al Relationship between intracranial pressure and other clinical variables in patients with aneurysmal subarachnoid hemorrhage Journal of Neurosurgery 2004; 408-16