The diagnostic accuracy of brain microdialysis during surgery: a qualitative systematic review

Monitoring of brain function and metabolism during surgery may be of benefit for patient outcome. Microdialysis is the only sampling technique to date that allows continuous monitoring of drug or metabolite concentrations in the extracellular fluid of multiple tissues in the brain. This qualitative systematic review aimed to determine whether microdialysis is a valid tool for detecting changes in tissue composition as would be expected upon changes in (induced) tissue metabolic composition during brain surgery. A systematic review was conducted by performing a MEDLINE search using the terms "Intraoperative Period" (Medical Subject Heading [MeSH]) OR "Surgery" [Subheading] OR "Monitoring, Intraoperative" [MeSH] AND "Microdialysis" [MeSH] AND "Brain" [MeSH]. Two reviewers independently assessed the methodological quality of the studies. For each study the grades of recommendation were determined. The search strategy yielded 46 publications in Medline. Data extraction was performed on 16 studies. The methodological quality of studies was low, with overall scores of 4 or 5. A quantitative analysis could not be performed because of lack of sufficient data. A qualitative analysis was positive with regard to the detection of different states of tissue composition by microdialysis. However, the levels of recommendation on the outcome statements were low, resulting in a grade D level of recommendation on all statements. The available evidence for the validity of cerebral microdialysis as a diagnostic tool during brain surgery is of low scientific quality. In order to develop cerebral microdialysis as a valid instrument for monitoring of brain metabolism during surgery, standardised clinical prospective studies in homogeneous patient populations are required.