Dextran 500 Improves Recovery of Inflammatory Markers: An In Vitro Microdialysis Study.

Cerebral microdialysis (CMD) is used in severe traumatic brain injury (TBI) in order to recover metabolites in brain extracellular fluid (ECF). To recover larger proteins and avoid fluid loss, albumin supplemented perfusion fluid (PF) has been utilised, but due to regulatory changes in the EU, this is no longer practicable. The aim with this study was to see if fluid-, absolute- (AR) - and relative (RR) recovery for the novel carrier Dextran 500 was better than conventional PF, for a range of cytokines and chemokines. An in vitro set-up mimicking conditions seen in the neurocritical care of TBI patients was used, utilizing 100 kDa MW cut-off CMD catheters inserted through a triple-lumen bolt cranial access device into an external solution with diluted cytokine standards in known concentrations for 48 hours (divided into 6-hours epochs). Samples were run on a 39-plex-Luminex assay to assess cytokine concentrations. We found that fluid recovery was inadequate in 50% of epochs with conventional PF, while Dextran PF overcame this limitation. The AR was higher in the Dextran PF samples for a majority of cytokines, and RR was significantly increased for six cytokines (eotaxin, IL-6, M-CSF, CCL3, RANTES and TGF-alpha). In summary, Dextran PF improved fluid and cytokine recovery as compared to conventional PF and is a suitable alternative to albumin supplemented PF for protein microdialysis.