In this dissertation 42 patients of the intensive care unit treated with severe sepsis / septic were followed in a prospective cohort study. Microcirculation of the oral mucosa was measured by sidestream darkfield imaging on seven consecutive days. In addition various clinical and laboratory-chemical parameters as well as the determination of intensive care unit scoring systems (APACHE-II-Score, SAPS-II and SOFA-Score) were assessed. There was a negative correlation between the microcirculation and the ICU scoring systems ( most apparent in the comparison of the APACHE II-Score with the MFI). In the analysis of late mortality significantly higher values are shown in the scores of the deceased. In addition, deceased showed higher heart rates, increased lactate, lower pH, increased catecholamine therapy, as well as the need for mechanical ventilation, but no significantly reduced microcirculation . SDF vascular microscopy is a recognized method for measuring microcirculation on the bedside. However, in order to use this procedure clinically, it requires further validation of the measurable parameters and the different evaluation methods.