Haemodilution for acute ischaemic stroke.

backgroundIschaemic stroke interrupts the flow of blood to part of the brain. Haemodilution is thought to improve the flow of blood to the affected areas of the brain and thus reduce infarct size.

objectivesThe objective of this review was to assess the effects of haemodilution in acute ischaemic stroke. SEARCH STRATEGY: We searched the Cochrane Stroke Group Trials Register (last searched January 2002), Medline (1966-June 2002) and conference abstracts. We contacted manufacturers and investigators in the field to identify any additional published and unpublished studies. SELECTION CRITERIA: Randomised trials of haemodilution treatment in people with acute ischaemic stroke. Only trials in which treatment was started within 72 hours of stroke onset were included. DATA COLLECTION AND ANALYSIS: Two reviewers assessed trial quality and independently extracted the data. MAIN

resultsEighteen trials were included. A combination of venesection and plasma volume expander was used in eight trials. Ten trials used plasma volume expander alone. The plasma volume expander was dextran 40 in 12 trials, hydroxyethyl starch (HES) in five trials and albumin in one trial. Two trials tested haemodilution in combination with another therapy. Evaluation was blinded in 11 trials. Five trials probably included some patients with intracerebral haemorrhage. Haemodilution did not significantly reduce deaths within the first four weeks (odds ratio 1.09, 95% confidence interval 0.86 to 1.38). Similarly, haemodilution did not influence deaths within three to six months (odds ratio 1.01, 95% confidence interval 0.84 to 1.22), or death and dependency or institutionalisation (odds ratio 0.98, 95% confidence interval 0.84 to 1.15). The results were similar in confounded and unconfounded trials, and in trials of isovolaemic and hypervolaemic haemodilution. No statistically significant benefits were documented for any particular type of haemodiluting agents, but the statistical power to detect effects of HES and albumin was weak. Six trials reported venous thromboembolic events. There was a tendency towards reduction in deep venous thrombosis and/or pulmonary embolism at three to six months follow-up (odds ratio 0.59, 95% confidence interval 0.33 to 1.06). There was no increased risk of serious cardiac events among haemodiluted patients. REVIEWER'S

conclusionsThe overall results of this review are compatible both with modest benefit and moderate harm of haemodilution therapy for acute ischaemic stroke. This therapy has not been proven to improve survival or functional outcome.