Competing interestsBB is a member of the advisory board of Pulsion Medical Systems. MG, PM, JR, AC, OB, Nilotinib msds NW, JS and MS declare that they have no competing interests.Authors’ contributionsMG conceived of the study design, carried out statistical analysis and drafted the manuscript. PM, OB and JR helped to draft the manuscript. AC supported statistical analysis. NW, JS and MS coordinated the study. BB conceived of the study design, coordinated the study and helped with statistical analysis and drafting of the manuscript. All authors read and approved the final manuscript.AcknowledgementsThe authors thank Katja Frahm (physician), Sebastian Rossee and Moritz Maracke (both medical students) for excellent technical assistance. Funding was restricted to institutional and departmental sources.

This work was presented in part at the American Society of Anesthesiologists Annual Meeting, October 2008, Orlando, FL, USA.
Microvascular dysfunction plays a pivotal role in the pathophysiology of septic shock and may occur even in the presence of normal systemic oxygen supply and mean arterial pressure [1]. In this regard, several vasoactive agents, including inotropes, vasodilators, and inodilators, have been investigated in the attempt to preserve or improve microcirculatory blood flow in patients with severe sepsis or septic shock [1-5].In recent years, much attention has been paid to the use of the calcium sensitizer levosimendan in the treatment of septic myocardial dysfunction [6-10]. Levosimendan increases myocardial contractility while simultaneously exerting vasodilatory properties via activation of ATP-dependent potassium channels (KATP) [11].

In addition, levosimendan Cilengitide exerts anti-ischemic, anti-inflammatory, and anti-apoptotic properties, thereby affecting important pathways in the pathophysiology of septic shock [12-14]. It has been speculated that, owing to these beneficial effects, levosimendan may positively affect myocardial performance and regional hemodynamics, thereby improving microcirculatory perfusion [6-10,12,15,16].The objective of the present randomized controlled, double-blinded clinical study was, therefore, to elucidate the effects of levosimendan on systemic and microvascular hemodynamics. On this basis, we aimed at rejecting the null hypothesis that there is no difference in sublingual microvascular blood flow – as measured by sidestream dark-field (SDF) imaging [17] – in patients with fluid-resuscitated septic shock treated with levosimendan as compared with an active comparator drug (that is, dobutamine).