Introduction
============

Microcirculatory dysfunction is a key element in the pathogenesis of severe sepsis and septic shock and is related to endothelial dysfunction. Studies *in vivo*have shown that infusion of magnesium sulphate increased endothelium-dependent vasodilatation in healthy people and patients with cardiac disorders, but the effect on the septic patient\'s vessels, especially small ones, is unknown. We hypothesized that magnesium sulphate infusion can improve microcirculation in patients with severe sepsis and septic shock.

Methods
=======

Six septic patients (mean age 56 ± 16 years), who had already been fluid resuscitated, underwent magnesium sulphate infusion 2 g over 60 minutes with additional volume loading and use of norepinephrine if required. Sublingual microcirculation was evaluated using side dark-field videomicroscopy (MicroScan^®^; MicroVisionMedical). Each patient\'s microcirculation was evaluated by examining three to six different sublingual areas (10 to 20 seconds/image). In all patients, measurements were obtained at baseline and after 60 minutes. Images were analyzed by semiquantitative scores of flow (mean flow index; proportion of perfused vessels) and density (total vascular density; perfused vascular density) of small vessels (\<20 μm). Data are presented as median values (percentiles 25 to 75).

Results
=======

Data of this study have shown that perfused vascular density increased from 9.7 (4.9 to 13.0) n/mm (at baseline) to 12.1 (10.1 to 13.6) n/mm (at 60 min), proportion of perfused vessels increased from 70 (40 to 83)% to 77 (67 to 85)% but without statistical significance, *P*= 0.068.

Conclusion
==========

Magnesium sulphate has a tendency to improve microcirculation in severe sepsis and septic shock patients, but further studies are needed to obtain more detailed results.
