Intraoperative Phlebotomies and Bleeding in Liver Transplantation: a Retrospective Cohort Study and Causal Analysis Protocol

Liver transplantation are surgeries associated with important bleeding and often require perioperative red blood cell (RBC) transfusions. Overall, between 20 and 85 % of liver transplant recipients receive at least one RBC transfusion during their surgery. Such transfusions are consistently associated with higher morbidity and mortality, although this causal association is still under debate in many surgical populations. Despite the lack of clear causative association between perioperative transfusions and worse outcomes, minimizing bleeding and transfusions is believed to improve postoperative outcomes. Many perioperative variables are associated with higher blood loss and need for perioperative transfusions: liver disease severity, preoperative anemia and coagulopathy, higher cardiac filling pressures and higher fluid administration, among others. However, few perioperative interventions have been shown to reduce bleeding and transfusion requirements in this population. Among them, the use of intraoperative phlebotomies to reduce portal and hepatic venous pressure during the dissection phase is a promising one, also described in liver resection surgery.

To further investigate the effects of intraoperative phlebotomies on intraoperative bleeding, perioperative transfusions and mortality, the Principal Investigator will conduct a retrospective cohort study with a propensity score based causal analysis.