The art of fluid administration and haemodynamic support is one of the most challenging aspects of current critical care practice. Although more than half the patients in intensive care units (ICU) receive blood transfusions there is little in the way of data to guide decisions on when to give transfusions. The American College of Physicians, among others, has published a transfusion However, this is based, not on controlled clinical trials, but on expert opinion. Despite these guidelines, transfusion practice varies widely
