BACKGROUND: Fluid loading and hyperosmolar solutions can modify the cortical brain microcirculation and the endothelial glycocalyx (EG). This study compared the short-term effects of liberal fluid loading with a restrictive fluid intake followed by osmotherapy with hypertonic saline (HTS) on cerebral cortical microcirculation and EG integrity in a rabbit craniotomy model. METHODS: The experimental rabbits were allocated randomly to receive either <2 mL/kg/h (group R, n=14) or 30 mL/kg/h (group L, n=14) of balanced isotonic fluids for 1 hour. Then, the animals were randomized to receive 5 mL/kg intravenous infusion of either 3.2% saline (group HTS, n=14) or 0.9% saline (group normal saline, n=13) in a 20-minute infusion. Microcirculation in the cerebral cortex based on sidestream dark-field imaging, a morphologic index of glycocalyx damage to sublingual and cortical brain microcirculation (the perfused boundary region), and serum syndecan-1 levels were evaluated. RESULTS: Lower cortical brain perfused small vessel density (P=0.0178), perfused vessel density (P=0.0286), and total vessel density (P=0.0447) were observed in group L, compared with group R. No differences were observed between the HTS and normal saline groups after osmotherapy. Cerebral perfused boundary region values (P=0.0692) and hematocrit-corrected serum syndecan-1 levels (P=0.0324) tended to be higher in group L than in group R animals. CONCLUSIONS: Liberal fluid loading was associated with altered cortical cerebral microcirculation and EG integrity parameters. The 3.2% saline treatment did not affect cortical cerebral microcirculation or EG integrity markers.

Clinical Biochemistry Faculty of Medicine Hradec Kralove Charles University

Department of Military Surgery Faculty of Military Health Sciences Hradec Kralove University of Defense Brno Czech Republic

Departments of Anesthesiology and Intensive Care Medicine

Departments of Anesthesiology and Intensive Care Medicine Departments of Anaesthesia Pain Management and Perioperative Medicine Dalhousie University Halifax NS Canada Department of Anesthesiology Perioperative Medicine and Intensive Care J E Purkinje University Masaryk Hospital Usti nad Labem Department of Research and Development University Hospital Hradec Kralove Hradec Kralove

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