The impact of blood transfusion on tissue oxygen delivery (DO) and tissue oxygen consumption (VO) is a subject of current clinical studies. The primary objective of this observational study is to evaluate and measure the parameters involved in determining DO and VO in early phase of septic patients. A secondary objective of this study is to assess the potential benefit of blood transfusion on tissue metabolism by serial measurements of lactic acid (Ac. Lac.).
A group of 29 patients were studied, each patient received between one to three units of fresh packed red blood cells (pRBC). Clinical and paraclinical criteria for sepsis and the plasma value of haemoglobin (Hb) was below 10g/dl represented study inclusion criteria. We evaluated Hb, HCT, SAO, SCVO, parameters which are involved in determination of DO andVO, before and after the transfusion of one unit of fresh packed red blood cells (pRBC). Values of Ac. Lac was also assessed in order to determine the type of metabolism (aerobic or anaerobic). Central venous oxygen saturation (SCVO), arterial blood oxygen saturation (SAO), haemoglobin (Hb), haematocrit (HTC) and Ac. Lac. were determined using Epoc blood analyser. The cardiac output (CO) and systemic vascular resistance (SVR) were monitored during blood transfusion, using Vigileo monitor (Edward’s Life Science, PreSep catheter kit). TheSAO was also monitored by pulse-oximetry.
Changes in Hb, HTC and SCVO before and after the RBC transfusion (which further determine VO) were statistically significant (p<0,001). A statistically significant increase (p<0,001) was obtained in Ac. Lac. values, before and after pRBC transfusion. SAO and CO directly involved in producing DO, were clinically monitored during blood transfusion and the results were constant.
Results obtained in this clinical study show an increase in DO2 in critically ill septic patients and also an increase in oxygen tissue uptake which is similar to VO2, this clearly show the benefit of pRBC transfusion. We discovered that the benefit of RBC transfusion on tissue metabolism in critically ill septic patients remain elusive because of lactic acid values increase during and after transfusion. Based on our findings we highly recommend that Hb values used as a single trigger for packed RBC transfusion should be further studied. We hereby conclude that the values of SCVO2 and lactic acid may be considered as an additional trigger for transfusion, also the values of Hb and HCT should not be neglected.

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