Towards optimized red blood cells ordering prior to cardiac surgery: a single center retrospective study

Background: Cardiac surgery is associated with a high rate of intraoperative transfusion, requiring pre- ordering or ordering of packed red blood cell (PRBC) before surgery. Our institutional strategy is based on a systematic type and screen (T/S) ordering of 3 PRBCs at the blood bank then stored in a dedicated refrigerator in the operating room for each patient scheduled for cardiac surgery. However, these PRBC units are not always transfused and are therefore at risk of destruction if temperature fluctuations are detected during transport and storage processes. In addition, these orders represent a burden for the blood bank. Therefore, it is relevant to move towards a more tailored PRBC order before cardiac surgery and challenge the systematic ordering protocol. Methods: The Transfusion Understanding Scoring Tool (TRUST) and the Transfusion Risk and Clinical Knowledge (TRACK) Score are designed to stratify blood transfusion needs in cardiac surgery. We retrospectively performed both scores for each patient scheduled for cardiac surgery. Then, we compared their performance to predict PRBC transfusion and determined the optimal threshold to optimize the preoperative PRBC order reflecting the needs of our population managed with our local standards. Results: Receiver operating characteristic (ROC) curves for prediction of PRBC transfusion using the two scores were computed for the whole cohort (n=1249). Both scores performed well (areas under ROC curves: 0.81 and 0.82 (95% CI) using the TRACK Score and the TRUST, respectively). A TRUST < 3 identified a subgroup of patients (53.6%) at low risk of transfusion. The availability of 1 T/S PRBC in the OR would cover the needs of the majority (92.5%) of this group. Conclusions: In our institution, the use of the TRUST preoperatively could offer a more tailored T/S PRBC order for the intraoperative period, especially in the low-risk transfusion group.