Mannitol for acute traumatic brain injury

Mannitol is sometimes effective in reversing acute brain swelling, but its effectiveness in the ongoing management of severe head injury remains unclear. There is evidence that, in prolonged dosage, mannitol may pass from the blood into the brain, where it might cause increased intracranial pressure.

To assess the effects of different mannitol therapy regimens, of mannitol compared to other intracranial pressure (ICP) lowering agents, and to quantify the effectiveness of mannitol administration given at other stages following acute traumatic brain injury.

The review drew on the search strategy for the Injuries Group as a whole. We checked reference lists of trials and review articles, and contacted authors of trials. The searches were last updated in April 2005.

Randomised trials of mannitol, in patients with acute traumatic brain injury of any severity. The comparison group could be placebo-controlled, no drug, different dose, or different drug. We excluded cross-over trials, and trials where the intervention was started more than eight weeks after injury.

The reviewers independently rated quality of allocation concealment and extracted the data. Relative risks (RR) and 95% confidence intervals (CI) were calculated for each trial on an intention to treat basis.

In the acute management of comatose patients with severe head injury, the administration of high-dose mannitol resulted in reduced mortality (RR= 0.56; 95% CI 0.39 to 0.79) and reduced death and severe disability (RR= 0.58; 95% CI 0.47 to 0.72) when compared with conventional-dose mannitol. One trial compared ICP-directed therapy to 'standard care' (RR for death= 0.83; 95% CI 0.47 to 1.46). One trial compared mannitol to pentobarbital (RR for death= 0.85; 95% CI 0.52 to 1.38). One trial compared mannitol to hypertonic saline (RR for death= 1.25; 95% CI 0.47 to 3.33). One trial tested the effectiveness of pre-hospital administration of mannitol against placebo (RR for death= 1.75; 95% CI 0.48 to 6.38).

High-dose mannitol may be preferable to conventional-dose mannitol in the acute management of comatose patients with severe head injury. Mannitol therapy for raised ICP may have a beneficial effect on mortality when compared to pentobarbital treatment, but may have a detrimental effect on mortality when compared to hypertonic saline. ICP-directed treatment shows a small beneficial effect compared to treatment directed by neurological signs and physiological indicators. There are insufficient data on the effectiveness of pre-hospital administration of mannitol.