Microcirculatory Oxygen Uptake in Sepsis

Sepsis, Septic Shock, Severe Sepsis

microcirculation, oxygen uptake, hypoxia, adenosine, central venous saturation, hypoxanthine, laserdoppler

Forearm vasoocclusive testing (VOT) will be performed with laser-doppler spectrophotometry system in septic patients on ICU. Microcirculatory oxygen uptake will be checked for prognostic value and for associations with tissue hypoxia markers and high central venus saturations.

Sepsis remains a common entity in critical care patients with remarkable mortality. Microcirculatory dysfunction plays a pivotal role in the pathophysiology of sepsis and organ dysfunction. The main causal mechanisms are vasoactive substances such as nitric oxide and endothelin, destroyed endothelial surfaces and microvascular occlusion by activated coagulation and leucocytes. Furthermore there is some knowledge from vasooclussive testing (VOT) based on near-infrared spectroscopy (NIRS) and assessing the proportion of perfused vessels determined with orthogonal polarization spectral and sidestream darkfield imaging techniques (SDF) that impaired microcirculation is associated with organ dysfunction and increased mortality. Despite these well-recognised evidence previous trails proving therapy guidance with microcirculatory parameters failed in demonstrating optimised outcome . Recent guidelines still recommend fluid therapy based on central venous pressure, mean arterial pressure, urine output and or blood lactate concentration. But especially the parameter central venous oxygen saturation (ScvO2) seems to be not unproblematic. Retrospective data analysis found higher mortality rates if ScvO2 is elevated. In the present study patients with sepsis, severe sepsis and septic shock will be evaluated on day 1 and day 4 and a follow up will be performed on day 180. Additional to clinical parameters of organ function, infection markers, global parameters of tissue hypoxia will be captured by measurements of adenosine and whose metabolites. Macrocirculatory cardiovascular function delivered by transpulmonary thermodilution technique will be assessed and local tissue perfusion and oxygen uptake will be measured with a transcutaneous laser-doppler spectrophotometry system in VOT. The aim of this study is to check: 1. Is microcirculatory oxygen uptake a prognostic value in sepsis? 2. Is it correlated with biomarkers of hypoxia? 3. Are high levels of ScvO2 caused by microcirculatory impairments or by hyperdynamic macrocirculation?

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