Blood loss, predictors of bleeding, transfusion practice and strategies of blood cell salvaging during liver transplantation

Abstract

Blood loss during liver transplantation (OLTx) is a common consequence of pre-existing abnormalities of the hemostatic system, portal hypertension with multiple collateral vessels, portal vein thrombosis, previous abdominal surgery, splenomegaly, and poor "functional" recovery of the new liver. The intrinsic coagulopathic features of end stage cirrhosis along with surgical technical difficulties make transfusion-free liver transplantation a major challenge, and, despite the improvements in understanding of intraoperative coagulation profiles and strategies to control blood loss, the requirements for blood or blood products remains high. The impact of blood transfusion has been shown to be significant and independent of other well-known predictors of posttransplant-outcome. Negative effects on immunomodulation and an increased risk of postoperative complications and mortality have been repeatedly demonstrated. Isovolemic hemodilution, the extensive utilization of thromboelastogram and the use of autotransfusion devices are among the commonly adopted procedures to limit the amount of blood transfusion. The use of intraoperative blood salvage and autologous blood transfusion should still be considered an important method to reduce the need for allogenic blood and the associated complications. In this article we report on the common preoperative and intraoperative factors contributing to blood loss, intraoperative transfusion practices, anesthesiologic and surgical strategies to prevent blood loss, and on intraoperative blood salvaging techniques and autologous blood transfusion. Even though the advances in surgical technique and anesthetic management, as well as a better understanding of the risk factors, have resulted in a steady decrease in intraoperative bleeding, most patients still bleed extensively. Blood transfusion therapy is still a critical feature during OLTx and various studies have shown a large variability in the use of blood products among different centers and even among individual anesthesiologists within the same center. Unfortunately, despite the large number of OLTx performed each year, there is still paucity of large randomized, multicentre, and controlled studies which indicate how to prevent bleeding, the transfusion needs and thresholds, and the "evidence based" perioperative strategies to reduce the amount of transfusion.

Perioperative bleeding in patients undergoing liver transplantation

“…The classic technique utilizing a venovenous bypass was initially suggested to be superior due to better haemodynamic stability, as well as reduced blood loss [27]. However, this has not been confirmed in further studies, which yield contrary results [28]. Furthermore, a novel piggyback technique was demonstrated to lower transfusion requirements in comparison to the conventional technique, which was explained by a less extensive dissection area, the avoidance of artificial bypass circuit, as well as a shorter warm ischaemia time affecting graft function [29].…”

“…On the other hand, a recently published Cochrane review did not confirm the superiority of one technique over the other [30]. Other surgical factors related with increased blood transfusion during LT include a history of previous upper abdominal surgery, portal vein thrombosis and, in children, previous portoenterostomy [26,28]. Although the duration of surgery was identified as independent predictor of intraoperative blood loss and the amount of RBCs transfused, the exact direction of this relationship has not been established as longer surgery time may also be a indicator of increased intraoperative difficulties, which also could be a consequence of increased bleeding [20].…”

“…Although the duration of surgery was identified as independent predictor of intraoperative blood loss and the amount of RBCs transfused, the exact direction of this relationship has not been established as longer surgery time may also be a indicator of increased intraoperative difficulties, which also could be a consequence of increased bleeding [20]. Moreover, the level of experience of the transplant team has also been claimed to impact the risk of perioperative bleeding but this has not been widely validated [28].…”

“…The likely explanation of this relationship is thought to be connected to the raw edges of partial liver grafts leaving them prone to surface bleeding. Other technical factors, such as the decreased size of the donor liver, portal vein hypoplasia and an inadequate graft-recipient body weight ratio were associated with transfusion requirements in several studies [28,32]. Prolonged cold ischaemia time and poor graft function due to decreased production of coagulation factors also significantly increase the risk of massive transfusion [28].…”

Thromboelastometric Profile in Patients with Prothrombotic Risk Factors Undergoing Liver Transplantation

“…Historically, OLT has been associated with transfusion of large amounts of blood derivatives [3][4][5][6][7]. Currently, there is a progressive reduction of perioperative blood loss due to advances in surgical skills, anesthetic management and coagulation monitoring in general [8][9][10][11][12].…”