Insufficient Cellular Oxygen in ICU Patients With Anaemia

Evidence is increasing that in some cases a Hb trigger of 7-8g/dl may be too low and te question arises whether an individualized red cell transfusion strategy may benefit critically ill patients. New studies have shown the potential of protoporphyrin IX-triple state lifetime technique to measure mitochondrial oxygenation tension (mitoPO2) in vivo, which possibly is an early indicator of oxygen disturbance in the cell and therefore a physiological trigger for red cell transfusion. The goals are: 1. Determining the feasibility of using mitoPO2 and the variability of mitoPO2 measurements in critically ill intensive care unit (ICU) patients before and after receiving a red cell transfusion 2. Describing the effects of red cell transfusion and the associated change in \[Hb\] on mitoPO2 and on other physiologic measures of tissue oxygenation and oxygen balance 3. Describing the association between mitoPO2 and vital organ functions. Included patients will undergo red cell transfusion as planned. However, red cell transfusion will be delayed by 2 hours. At multiple predefined moments data collection including blood samples and measurements of mitoPO2 will take place. The results of this study cannot be immediately translated to clinical practice. Using these results, the investigators will design a phase 2 diagnostic study, most probably a randomized clinical trial that will yield applied knowledge with respect to personalizing red cell transfusion. Application will be in ICU patients with anaemia who might or might not profit from red cell transfusions. It will lead to a reduction of both over- and under- transfusion.