The Effect of Dexmedetomidine on Microcirculation in Severe Sepsis

Despite early goal-directed maintenance of normal macrocirculation, the reduction of 60-day mortality of patients with severe sepsis and septic shock remained unsatisfied (56.9% to 44.3%). One of the major causes of high mortality is microcirculatory dysfunction. Delayed diagnosis and treatment of microcirculatory dysfunction may cause tissue hypoperfusion and resulted in multiple organ dysfunction and death. Dexmedetomidine is a highly selective α2-adrenoreceptor agonist which exhibits sedative and analgesic effects. Recent studies suggest that dexmedetomidine also has anti-coagulation and anti-inflammatory effects, and it can reduce the mortality of endotoxemic rats and patients with severe sepsis. The investigators will conduct two animal studies and one clinical trial to investigate the effect of dexmedetomidine on microcirculatory dysfunction and organ injury in rat with endotoxemia and patients with severe sepsis and septic shock. Sixty patients with severe sepsis and septic shock will be enrolled and randomized to control group or dexmedetomidine group. In the control group, the patients will be treated according to the clinical practice guideline. If sedation is required, non-dexmedetomidine sedative agents will be used. In the dexmedetomidine group, the patients will be treated according to the clinical practice guideline, and they will also receive continuous infusion of dexmedetomidine (infusion rate ranged from 0.1 to 0.7 mcg/kg/h) for 24 hours as needed. The sublingual microcirculation, serum level of Endocan, NGAL(Neutrophil Gelatinase-Associated Lipocalin), and BNP(B-type natriuretic peptide) will be examined at preset time points up to 24 hours. The vital signs, hemodynamic parameters, and survival of 28-day and 90-day will be recorded and analyzed.