Predicting the Need for Intra-operative Large Volume Blood Transfusions During Thoraco-abdominal Aortic Aneurysm Repair

Objective Thoraco-abdominal aortic aneurysm (TAAA) repair is a complex procedure performed in patients at high cardiovascular risk. High volume intra-operative bleeding is often recorded, and the amount of intra-operative blood product transfusion is associated with relevant morbidity and mortality. The aim of the study was to identify pre-operative predictors of intra-operative large volume blood transfusions (LVBT) to stratify patients pre-operatively. Methods This was a retrospective analysis of prospectively collected data of all patients who underwent open TAAA surgery at San Raffaele Scientific Institute from January 2009 to December 2015. Intra-operative red blood cell (RBC) transfusions were administered to maintain a hematocrit of at least 30%. A LVBT was defined as a transfusion of at least four RBC units, corresponding to 1000 mL. Results The study population included 428 patients: 260 (61%) received fewer than 4 RBC units, and 168 (39%) were transfused with at least 4 RBC units. In patients who underwent LVBT, higher mortality was observed after surgery (p=.003), longer intensive care unit admission (p=.004), and longer mechanical ventilation compared with less transfused patients (p=.0002). The patients who received fewer units were administered a higher dose of heparin during the surgical operation compared with patients of the LVBT group: 3400±1100 vs. 2900±1300 IU (international units) (p=.0004). Pre-operative chronic renal failure (OR 1.8), the pre-operative haemoglobin value (OR 0.8), and the need for urgent or emergent surgery (OR 3.15) were independent predictors of LVBT on multivariate analysis. Conclusions The identification of patients at risk of intra-operative LVBT during TAAA surgery is critical as these patients experience a worse outcome. Nevertheless, only few independent predictors are available for clinical practice.