• Marcos L Miranda, Michelle M Balarini, and Eliete Bouskela.
• From the Laboratory for Clinical and Experimental Research in Vascular Biology-BioVasc, Department of Physiological Sciences, Biomedical Center, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil (M.L.M., E.B.); and Internal Medicine Department, Andaraí Federal Hospital, Rio de Janeiro, RJ, Brazil (M.M.B.).
• Anesthesiology. 2015 Mar 1;122(3):619-30.

BackgroundDexmedetomidine, an α-2 adrenergic receptor agonist, has already been used in septic patients although few studies have examined its effects on microcirculatory dysfunction, which may play an important role in perpetuating sepsis syndrome. Therefore, the authors have designed a controlled experimental study to characterize the microcirculatory effects of dexmedetomidine in an endotoxemia rodent model that allows in vivo studies of microcirculation.MethodsAfter skinfold chamber implantation, 49 golden Syrian hamsters were randomly allocated in five groups: (1) control animals; (2) nonendotoxemic animals treated with saline; (3) nonendotoxemic animals treated with dexmedetomidine (5.0 μg kg h); (4) endotoxemic (lipopolysaccharide 1.0 mg/kg) animals treated with saline; and (5) endotoxemic animals treated with dexmedetomidine. Intravital microscopy of skinfold chamber preparations allowed quantitative analysis of microvascular variables and venular leukocyte rolling and adhesion. Mean arterial blood pressure, heart rate, arterial blood gases, and lactate concentrations were also documented.ResultsLipopolysaccharide administration increased leukocyte rolling and adhesion and decreased capillary perfusion. Dexmedetomidine significantly attenuated these responses: compared with endotoxemic animals treated with saline, those treated with dexmedetomidine had less leukocyte rolling (11.8 ± 7.2% vs. 24.3 ± 15.0%; P < 0.05) and adhesion (237 ± 185 vs. 510 ± 363; P < 0.05) and greater functional capillary density (57.4 ± 11.2% of baseline values vs. 45.9 ± 11.2%; P < 0.05) and erythrocyte velocity (68.7 ± 17.6% of baseline values vs. 54.4 ± 14.8%; P < 0.05) at the end of the experiment.ConclusionsDexmedetomidine decreased lipopolysaccharide-induced leukocyte-endothelial interactions in the hamster skinfold chamber microcirculation. This was accompanied by a significant attenuation of capillary perfusion deficits, suggesting that dexmedetomidine yields beneficial effects on endotoxemic animals' microcirculation.

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