Haemodilution for acute ischaemic stroke

Asplund K

Published Online:

January 21, 2009

Dilution of the blood to improve compromised brain blood flow in patients with acute stroke is not beneficial. Most strokes are caused by a blood clot that interrupts blood flow to a part of the brain. If blood flow is not restored early, the brain cells will die (brain infarction). Haemodilution (dilution of the blood) improves the flow properties of the blood so that, theoretically, oxygen and nutrient supply to the brain is improved and brain cells threatened to die could survive. This treatment has been shown to reduce brain infarct size in animals with experimental stroke. Haemodilution can be achieved by bloodletting, by giving fluids as an infusion or by a combination of both. The fluids used may be simple salt solutions but so-called colloid solutions are more effective as haemodilution agents. In many countries, haemodilution has been used in routine clinical treatment of patients with acute stroke since the late 1970s when the first studies were published. Since then, a large number of clinical studies on haemodilution in acute stroke have been published. This review shows that when all the studies are taken together there are no benefits from this treatment. There is no evidence that any particular mode of haemodilution, with or without blood-letting, using various kinds of haemodiluting agents, etc. is effective. It is concluded that there is no scientific support for the use of haemodilution in the routine treatment of patients with acute stroke.

Abstract (click to read)

Background:

Ischaemic 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.

Objectives:

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 to 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 We contacted manufacturers and investigators in the field to identify any additional published and unpublished studies.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 results:

Eighteen 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 (OR) 1.01, 95% confidence interval (CI) 0.84 to 1.22), or death and dependency or institutionalisation (OR 0.98, 95% CI 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 (OR 0.59, 95% CI 0.33 to 1.06). There was no increased risk of serious cardiac events among haemodiluted patients.

Authors' conclusions:

The 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.

This record should be cited as:

Asplund K. Haemodilution for acute ischaemic stroke. Cochrane Database of Systematic Reviews 2002, Issue 4. Art. No.: CD000103. DOI: 10.1002/14651858.CD000103

Assessed as up to date:

August 14, 2002

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Primary Review Group:

Stroke Group

Health topics:

Heart & circulation > Stroke > Ischemic stroke/TIA: treatment

Neurology > Stroke > Ischemic stroke/TIA: treatment

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Independent high-quality evidence for health care decision making

Haemodilution for acute ischaemic stroke

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