This prospective observational study investigated the effects of leukoreduced packed red blood cell transfusion on the microcirculation in patients undergoing cardiopulmonary bypass for coronary artery graft and/or cardiac valve replacement procedures. While non-pulsatile pump flow was maintained constant, the transfusion of one to three "old" blood units (storage time: 18 3 days) was associated with an increase in sublingual microcirculatory density and oxygen saturation suggesting an enhancement of tissue oxygen availability. Using a quite interesting methodology (sublingual sidestream dark field imaging and sublingual reflectance spectrophotometry), the authors demonstrated an important and clinically relevant effect of blood transfusion. However, the results of this study need to be interpreted within its context: fixed non-pulsatile blood flow and hypothermic conditions (32.7 0.9C).
– Philippe Van der Linden