This prospective randomized single blinded study evaluated the efficacy of acute normovolemic hemodilution in addition to esmolol-induced controlled hypotension during spinal surgery. The design of the study was quite interesting because, in contrast to other agents (mainly vasodilators) used to induce hypotension, betablockers did not seem to influence the redistribution of blood flow occurring physiologically during acute isovolemic anemia. The authors demonstrated that the addition of ANH to their protocol significantly reduced the use of allogeneic blood. One limitation of this study was that the postoperative transfusion trigger was not clearly defined.

– Philippe Van der Linden