Derivation of a risk index for the prediction of massive blood transfusion in liver transplantation

2023 Clinical Update in Liver Transplantation

Liver transplantation continues to provide life-saving treatment for patients with end-stage liver disease. Advances in the field of transplant anesthesia continue to support the care of more complex patients. The use of extracorporeal membrane oxygenation has been described in critical care settings and cardiac surgery but may be a valuable option for specific conditions for patients undergoing liver transplantation. Changes to the allocation process for liver grafts now focus on acuity circles to reduce regional disparities. As the number of life-saving transplant surgeries increases, so does the need for specialty knowledge in the anesthetic considerations of these procedures. The specialty of transplant anesthesia continues to grow and develop to meet the demands of complex patients and the increased number of transplants performed. Liver transplantation can be a resource-demanding procedure, and predicting the need for massive transfusion can aid in planning and preparing for significant blood loss.

Predictive role of hepatic venous pressure gradient in bleeding events among patients with cirrhosis undergoing orthotopic liver transplantation

Background & Aims

Major bleeding events during orthotopic liver transplantation (OLT) are associated with poor outcomes. The proportion of this risk related to portal hypertension is unclear. Hepatic venous pressure gradient (HVPG) is the gold standard for estimating portal hypertension. The aim of this study was to analyze the ability of HVPG to predict intraoperative major bleeding events during OLT in patients with cirrhosis.

Methods

We retrospectively analyzed a prospective database including all patients with cirrhosis who underwent OLT between 2010 and 2020 and had liver and right heart catheterizations as part of their pre-transplant assessment. The primary endpoint was the occurrence of an intraoperative major bleeding event.

Results

The 468 included patients had a median HVPG of 17 mmHg [interquartile range, 13-22] and a median MELD on the day of OLT of 16 [11-24]. Intraoperative red blood cell transfusion was required in 72% of the patients (median 2 units transfused), with a median blood loss of 1,000 ml [575-1,500]. Major intraoperative bleeding occurred in 156 patients (33%) and was associated with HVPG, preoperative hemoglobin level, severity of cirrhosis at the time of OLT (MELD score, ascites, encephalopathy), hemostasis impairment (thrombocytopenia, lower fibrinogen levels), and complications of cirrhosis (sepsis, acute-on-chronic liver failure). By multivariable regression analysis with backward elimination, HVPG, preoperative hemoglobin level, MELD score, and tranexamic acid infusion were associated with the primary endpoint. Three categories of patients were identified according to HVPG: low-risk (HVPG <16 mmHg), high-risk (HVGP ≥16 mmHg), and very high-risk (HVPG ≥20 mmHg).

Conclusions

HVPG predicted major bleeding events in patients with cirrhosis undergoing OLT. Including HVPG as part of pre-transplant assessment might enable better anticipation of the intraoperative course.

Impact and implications

Major bleeding events during orthotopic liver transplantation (OLT) are associated with poor outcomes but the proportion of this risk related to portal hypertension is unclear. Our work shows that hepatic venous pressure gradient (HVPG), the gold standard for estimating portal hypertension, is a strong predictor of major bleeding events and blood loss volume in patients with cirrhosis undergoing OLT. Three groups of patients can be identified according to their risk of major bleeding events: low-risk patients with HVPG <16 mmHg, high-risk patients with HVPG ≥16 mmHg, and very high-risk patients with HVPG ≥20 mmHg. HVPG could be systematically included in the pre-transplant assessment to anticipate intraoperative course and tailor patient management.

Implementation of a Bleeding Management Algorithm in Liver Transplantation: A Pilot Study

Objectives

The aims of the study were to compare the consumption of blood products before and after the implementation of a bleeding management algorithm in patients undergoing liver transplantation and to determine the feasibility of a multicentre, randomized study.

Background

Liver transplantation remains the only curative therapy for patients with end-stage liver disease, but it carries a high risk of surgical bleeding.

Materials and Methods

Retrospective study of patients treated before (group 1) and after (group 2) implementation of a haemostatic algorithm guided by viscoelastic testing, including use of lyophilized coagulation factor concentrates (prothrombin complex and fibrinogen concentrates). Primary outcome was the number of units of blood products transfused in 24 h after surgery. Secondary outcomes included hospital stay, mortality, and cost.

Results

Data from 30 consecutive patients was analysed; 14 in group 1 and 16 in group 2. Baseline data were similar between groups. Median total blood product consumption 24 h after surgery was 33 U (IQR: 11-57) in group 1 and 1.5 (0-23.5) in group 2 (p = 0.028). Significantly fewer units of red blood cells, fresh frozen plasma, and cryoprecipitate were transfused in group 2 versus group 1. There was no significant difference in complications, hospital stay, or in-hospital mortality between groups. The cost of haemostatic therapy was non-significantly lower in group 2 versus group 1 (7,400 vs. 15,500 USD; p = 0.454).

Conclusion

The haemostatic management algorithm was associated with a significant reduction in blood product use during 24 h after liver transplantation. This study demonstrated the feasibility and provided a sample size calculation for a larger, randomized study.

Role of intelligent/interactive qualitative and quantitative analysis-three-dimensional estimated model in donor-recipient size mismatch following deceased donor liver transplantation

BACKGROUND

Donor-recipient size mismatch (DRSM) is considered a crucial factor for poor outcomes in liver transplantation (LT) because of complications, such as massive intraoperative blood loss (IBL) and early allograft dysfunction (EAD). Liver volumetry is performed routinely in living donor LT, but rarely in deceased donor LT (DDLT), which amplifies the adverse effects of DRSM in DDLT. Due to the various shortcomings of traditional manual liver volumetry and formula methods, a feasible model based on intelligent/interactive qualitative and quantitative analysis-three-dimensional (IQQA-3D) for estimating the degree of DRSM is needed.

AIM

To identify benefits of IQQA-3D liver volumetry in DDLT and establish an estimation model to guide perioperative management.

METHODS

We retrospectively determined the accuracy of IQQA-3D liver volumetry for standard total liver volume (TLV) (sTLV) and established an estimation TLV (eTLV) index (eTLVi) model. Receiver operating characteristic (ROC) curves were drawn to detect the optimal cut-off values for predicting massive IBL and EAD in DDLT using donor sTLV to recipient sTLV (called sTLVi). The factors influencing the occurrence of massive IBL and EAD were explored through logistic regression analysis. Finally, the eTLVi model was compared with the sTLVi model through the ROC curve for verification.

RESULTS

A total of 133 patients were included in the analysis. The Changzheng formula was accurate for calculating donor sTLV (P = 0.083) but not for recipient sTLV (P = 0.036). Recipient eTLV calculated using IQQA-3D highly matched with recipient sTLV (P = 0.221). Alcoholic liver disease, gastrointestinal bleeding, and sTLVi > 1.24 were independent risk factors for massive IBL, and drug-induced liver failure was an independent protective factor for massive IBL. Male donor-female recipient combination, model for end-stage liver disease score, sTLVi ≤ 0.85, and sTLVi ≥ 1.32 were independent risk factors for EAD, and viral hepatitis was an independent protective factor for EAD. The overall survival of patients in the 0.85 < sTLVi < 1.32 group was better compared to the sTLVi ≤ 0.85 group and sTLVi ≥ 1.32 group (P < 0.001). There was no statistically significant difference in the area under the curve of the sTLVi model and IQQA-3D eTLVi model in the detection of massive IBL and EAD (all P > 0.05).

CONCLUSION

IQQA-3D eTLVi model has high accuracy in predicting massive IBL and EAD in DDLT. We should follow the guidance of the IQQA-3D eTLVi model in perioperative management.

Risk factors of massive blood transfusion in liver transplantation: consequences and a new index for prediction including the donor

BACKGROUND

Massive blood transfusion (MBT) is a common occurrence in liver transplant (LT) patients. Recipient-related risk factors include cirrhosis, history of multiple surgeries and suboptimal donors. Despite advances in surgical techniques, anesthetic management and graft preservation have decreased the need for transfusions, this complication has not been completely eliminated.

METHODS

One thousand four hundred and sixty-nine LT were performed at our institution between May 2003 and December 2020, and data was available regarding transfusion for 1198 of them. We divided the patients into two groups, with regards to transfusion of 6 or more units of packed red blood cells in the first 24 h posttransplant, and we analyzed the differences between the groups.

RESULTS

Out of the 1198 patients, 607 (50.7%) met criteria for MBT. Survival was statistically lower at 1, 3, and 5 years when comparing the groups that had MBT to those that did not (92.6%, 85.2% and 79.7%, respectively, in the non MBT group, vs. 78.1%, 71.6% y 66.8%, respectively, in the MBT group). MBT was associated with a 1.5 mortality risk as opposed to non-MBT patients. Logistical regression analysis of our variables yielded the following results for a new model, including serum creatinine (OR 1.97), sodium (OR 1.73), hemoglobin (OR 1.99), platelets (OR 1.37), INR (OR 1.4), uDCD (OR 2.13) and split liver donation.

CONCLUSION

Massive blood transfusion impacts patient survival in a statistically significant way. The most significant risk factors are preoperative hemoglobin, INR and serum creatinine.

Intraoperative blood loss and blood transfusion requirement among liver transplant recipients: A national single-center experience 2020

BACKGROUND

Liver transplantation (LT) is a complicated surgical procedure with high risk for massive intraoperative blood loss due to pre-existing coagulopathy, portosystemic shunts with collateral circulations, and splenomegaly. The transfusion service will direct most of their resources toward LT programs with great impact on cost. The purpose of this study was to evaluate single center transfusion strategies and to identify the risk factors associated with the intraoperative blood loss and blood transfusion.

METHODS

The study includes 18 patients who underwent LT at Hospital Selayang between January 2020 and December 2020. Retrospective analysis of data included preoperative assessment of coagulopathy, intraoperative blood loss, and blood component transfusion.

RESULTS

The mean age in the study group was 36.4 ± 12.68 years. The mean intraoperative blood loss was 4450 ± 1646 ml requiring 4.17 ± 3.3 packed red blood cell (PRBC) units, 7.56 ± 5.5 platelet units, and 9.50 ± 6.0 fresh-frozen plasma units. The independent risk factor for high blood loss (HBL) group was lower preoperative platelet count and it is statistically significant (P = 0.024). The HBL group is associated with higher usage of PRBC (P = 0.024) and platelet units (P = 0.031) and it is statistically significant. The length of stay (LOS) in intensive care unit (ICU) averaging 8.6 ± 4.95 days, and there is no significant differences comparing the HBL and LBL group (P = 0.552). The mortality <90 days for all recipients was 22.2%.

CONCLUSION

The preoperative platelet count for is the most important factor associated with HBL in LT procedure. The usage of PRBC and platelet units was statistically higher in the HBL group. Comparing HBL and LBL patients, there is no difference in terms of the LOS in ICU postoperatively. A larger sample size would be needed in view of relatively small sample size.

Systematic review highlights high risk of bias of clinical prediction models for blood transfusion in patients undergoing elective surgery

BACKGROUND

Blood transfusion can be a lifesaving intervention after perioperative blood loss. Many prediction models have been developed to identify patients most likely to require blood transfusion during elective surgery, but it is unclear whether any are suitable for clinical practice.

STUDY DESIGN AND SETTING

We conducted a systematic review, searching MEDLINE, Embase, PubMed, The Cochrane Library, Transfusion Evidence Library, Scopus, and Web of Science databases for studies reporting the development or validation of a blood transfusion prediction model in elective surgery patients between January 1, 2000 and June 30, 2021. We extracted study characteristics, discrimination performance (c-statistics) of final models, and data, which we used to perform risk of bias assessment using the Prediction model risk of bias assessment tool (PROBAST).

RESULTS

We reviewed 66 studies (72 developed and 48 externally validated models). Pooled c-statistics of externally validated models ranged from 0.67 to 0.78. Most developed and validated models were at high risk of bias due to handling of predictors, validation methods, and too small sample sizes.

CONCLUSION

Most blood transfusion prediction models are at high risk of bias and suffer from poor reporting and methodological quality, which must be addressed before they can be safely used in clinical practice.

Patient Blood Management in Liver Transplant—A Concise Review

Transfusion of blood products in orthotopic liver transplantation (OLT) significantly increases post-transplant morbidity and mortality and is associated with reduced graft survival. Based on these results, an active effort to prevent and minimize blood transfusion is required. Patient blood management is a revolutionary approach defined as a patient-centered, systematic, evidence-based approach to improve patient outcomes by managing and preserving a patient’s own blood while promoting patient safety and empowerment. This approach is based on three pillars of treatment: (1) detecting and correcting anemia and thrombocytopenia, (2) minimizing iatrogenic blood loss, detecting, and correcting coagulopathy, and (3) harnessing and increasing anemia tolerance. This review emphasizes the importance of the three-pillar nine-field matrix of patient blood management to improve patient outcomes in liver transplant recipients.

Viscoelastic Management of Coagulopathy during the Perioperative Period of Liver Transplantation

Viscoelastic testing (VET) in liver transplantation (LT) has been used since its origin, in combination with standard laboratory testing (SLT). There are only a few, small, randomized controlled trials that demonstrated a reduction in transfusion rates using VET to guide coagulation management. Retrospective analyses contrasting VET to SLT have demonstrated mixed results, with a recent concern for overtreatment and the increase in postoperative thrombotic events. An oversight of many studies evaluating VET in LT is a single protocol that does not address the different phases of surgery, in addition to pre- and postoperative management. Furthermore, the coagulation spectrum of patients entering and exiting the operating room is diverse, as these patients can have varying anatomic and physiologic risk factors for thrombosis. A single transfusion strategy for all is short sighted. VET in combination with SLT creates the opportunity for personalized resuscitation in surgery which can address the many challenges in LT where patients are at a paradoxical risk for both life-threatening bleeding and clotting. With emerging data on the role of rebalanced coagulation in cirrhosis and hypercoagulability following LT, there are numerous potential roles in VET management of LT that have been unaddressed.

Haemostasis in cirrhosis: Understanding destabilising factors during acute decompensation

Hospitalised patients with decompensated cirrhosis are in a rebalanced haemostatic state due to a parallel decline in both pro- and anti-haemostatic pathways. However, this rebalanced haemostatic state is highly susceptible to perturbations and may easily tilt towards hypocoagulability and bleeding. Acute kidney injury, bacterial infections and sepsis, and progression from acute decompensation to acute-on-chronic liver failure are associated with additional alterations of specific haemostatic pathways and a higher risk of bleeding. Unfortunately, there is no single laboratory method that can accurately stratify an individual patient's bleeding risk and guide pre-procedural prophylaxis. A better understanding of haemostatic alterations during acute illness would lead to more rational and individualised management of hospitalised patients with decompensated cirrhosis. This review will outline the latest findings on haemostatic alterations driven by acute kidney injury, bacterial infections/sepsis, and acute-on-chronic liver failure in these difficult-to-treat patients and provide evidence supporting more tailored management of bleeding risk.

Portal hypertension has no role in perioperative bleeding during liver transplantation with systematic porto-caval shunt

BACKGROUND

More than a half of patients undergoing liver transplantation (LT) receive intraoperative transfusion. Portal hypertension (PHT) may contribute to perioperative blood loss. We study the relationship between preoperative hepatic venous pressure gradient (HVPG) values and intraoperative transfusion requirements in adult patients undergoing LT.

METHODS

160 cirrhotic patients undergoing first elective LT (2009-2019) with an HVPG measurement within the previous 6 months were included. Surgical technique was piggyback with portocaval shunt (PCS). The association of HVPG and other variables with transfusion requirements and blood loss were studied.

RESULTS

Blood loss (ml/kg) was positively correlated with HVPG, among other variables, but at multivariable analysis it only remained associated with MELD-Na and HCC indication. Regarding RBC transfusion, MELD-Na and hemoglobin were independently associated with the need and magnitude of RBC transfusion. Subanalysis by surgical stage (hepatectomy, anhepatic, neohepatic) and by serial HVPG cut-offs found no clear associations with either bleeding or transfusion.

DISCUSSION

The severity of PHT plays a minor role on bleeding and transfusion during LT in a contemporary cohort with systematic PCS. Main determinants of transfusion are liver function and baseline hemoglobin, which would seem the suitable goal to optimize transfusion in LT.

Days alive and out of hospital after liver transplant: comparing a patient-centered outcome between recipients of grafts from donation after circulatory and brain deaths

We retrospectively compared outcomes between recipients of donation after circulatory death (DCD) and donation after brain death (DBD) liver allografts using days alive and out of hospital (DAOH), a composite outcome of mortality, morbidity, and burden of care from patient perspective. The initial length of stay and duration of any subsequent readmission for the first year after liver transplantation were recorded. Donor category and perioperative and intraoperative characteristics pertinent to liver transplantation were included. The primary outcome was DAOH₃₆₅. Secondary outcomes included early allograft dysfunction and hepatic arterial and biliary complications. Although the incidence of both early allograft dysfunction (P < .001) and ischemic cholangiopathy (P < .001) was significantly greater in the recipients of DCD, there were no significant differences in the length of stay and DAOH₃₆₅. The median DAOH₃₆₅ was 355 days for recipients of DBD allografts and 353 days for recipients of DCD allografts (P = .34). Increased transfusion burden, longer cold ischemic time, and non-White recipients were associated with decreased DAOH. There were no significant differences in graft failure (P = .67), retransplantation (P = .67), or 1-year mortality (P = .96) between the 2 groups. DAOH is a practical and attainable measure of outcome after liver transplantation. This metric should be considered for quality measurement and reporting in liver transplantation.

Blood products and liver transplantation: A strategy to balance optimal preparation with effective blood stewardship

BACKGROUND

Unanticipated transfusion requirements during liver transplantation can delay lifesaving intraoperative resuscitation and strain blood bank resources. Risk-stratified preoperative blood preparation can mitigate these deleterious outcomes.

STUDY DESIGN AND METHODS

A two-tiered blood preparation protocol for liver transplantation was retrospectively evaluated. Eleven binary variables served as criteria for high-risk (HR) allocation. Primary outcomes included red blood cell (RBC), plasma (FFP), and platelet (Plt) utilization. Secondary outcomes included product under- and overpreparation. Contingency tables for transfusion requirements above the population means were generated using 15 clinical variables. Modified protocols were developed and retrospectively optimized using the study population.

RESULTS

Of 225 recipients, 102 received HR preoperative orders, which correlated to higher intraoperative transfusion requirements. However, univariate analysis identified only two statistical risk factors per product: Hgb ≤7.8 g/dl (p < .001) and MELD ≥38 (p = .035) for RBCs, Hgb ≤7.8 g/dl (p = .002) and acute alcoholic hepatitis (p = 0.015) for FFP, and Hgb ≤7.8 g/dl (p = .001) and normothermic liver preservation (p = .037) for Plts. Based on these findings, we developed modified protocols for individual products, which were evaluated retrospectively for their effectiveness at reducing under-preparatory events while limiting product overpreparation. Cohort statistics were used to define the preparation strategy for each protocol. Retrospective comparative analysis demonstrated the superiority of the modified protocols by improving the under-preparation rate from 24% to <10% for each product, which required a 1.56-fold and 1.44-fold increase in RBC and FFP overpreparation, respectively. Importantly, there was no difference in Plt overpreparation.

DISCUSSION

We report translatable data-driven blood bank preparation protocols for liver transplantation.

Development of Machine Learning Models Predicting Estimated Blood Loss during Liver Transplant Surgery

The incidence of major hemorrhage and transfusion during liver transplantation has decreased significantly over the past decade, but major bleeding remains a common expectation. Massive intraoperative hemorrhage during liver transplantation can lead to mortality or reoperation. This study aimed to develop machine learning models for the prediction of massive hemorrhage and a scoring system which is applicable to new patients. Data were retrospectively collected from patients aged >18 years who had undergone liver transplantation. These data included emergency information, donor information, demographic data, preoperative laboratory data, the etiology of hepatic failure, the Model for End-stage Liver Disease (MELD) score, surgical history, antiplatelet therapy, continuous renal replacement therapy (CRRT), the preoperative dose of vasopressor, and the estimated blood loss (EBL) during surgery. The logistic regression model was one of the best-performing machine learning models. The most important factors for the prediction of massive hemorrhage were the disease etiology, activated partial thromboplastin time (aPTT), operation duration, body temperature, MELD score, mean arterial pressure, serum creatinine, and pulse pressure. The risk-scoring system was developed using the odds ratios of these factors from the logistic model. The risk-scoring system showed good prediction performance and calibration (AUROC: 0.775, AUPR: 0.753).

Advancing Prediction of Risk of Intraoperative Massive Blood Transfusion in Liver Transplantation With Machine Learning Models. A Multicenter Retrospective Study

Background

Liver transplantation surgery is often accompanied by massive blood loss and massive transfusion (MT), while MT can cause many serious complications related to high mortality. Therefore, there is an urgent need for a model that can predict the demand for MT to reduce the waste of blood resources and improve the prognosis of patients.

Objective

To develop a model for predicting intraoperative massive blood transfusion in liver transplantation surgery based on machine learning algorithms.

Methods

A total of 1,239 patients who underwent liver transplantation surgery in three large grade lll-A general hospitals of China from March 2014 to November 2021 were included and analyzed. A total of 1193 cases were randomly divided into the training set (70%) and test set (30%), and 46 cases were prospectively collected as a validation set. The outcome of this study was an intraoperative massive blood transfusion. A total of 27 candidate risk factors were collected, and recursive feature elimination (RFE) was used to select key features based on the Categorical Boosting (CatBoost) model. A total of ten machine learning models were built, among which the three best performing models and the traditional logistic regression (LR) method were prospectively verified in the validation set. The Area Under the Receiver Operating Characteristic Curve (AUROC) was used for model performance evaluation. The Shapley additive explanation value was applied to explain the complex ensemble learning models.

Results

Fifteen key variables were screened out, including age, weight, hemoglobin, platelets, white blood cells count, activated partial thromboplastin time, prothrombin time, thrombin time, direct bilirubin, aspartate aminotransferase, total protein, albumin, globulin, creatinine, urea. Among all algorithms, the predictive performance of the CatBoost model (AUROC: 0.810) was the best. In the prospective validation cohort, LR performed far less well than other algorithms.

Conclusion

A prediction model for massive blood transfusion in liver transplantation surgery was successfully established based on the CatBoost algorithm, and a certain degree of generalization verification is carried out in the validation set. The model may be superior to the traditional LR model and other algorithms, and it can more accurately predict the risk of massive blood transfusions and guide clinical decision-making.

Safety and Efficacy of Tranexamic Acid to Minimise Perioperative Bleeding in Hepatic Surgery: A Systematic Review and Meta-Analysis

INTRODUCTION

Perioperative bleeding poses a major risk during liver surgery, which can result in increased transfusion requirements, morbidity, and mortality. Tranexamic acid (TXA) effectively reduces perioperative bleeding and transfusion requirements in trauma patients. However, there remains a lack of evidence of its use in liver surgery. This meta-analysis of randomised controlled trials evaluated the efficacy and safety of TXA in liver resection and transplantation.

METHOD

A comprehensive search of Medline, Embase, CENTRAL and Clinicaltrials.gov databases was undertaken to identify studies from January 1947 to September 2021. The outcomes of the need for blood transfusion, thromboembolic events and mortality were extracted from the included studies. Quantitative pooling of data was based on the random effects model.

RESULTS

Six studies reporting on 429 patients were included. TXA reduced the need for perioperative blood transfusion in liver resection and transplantation (OR 0.09; 95% CI 0.01 to 0.72). More importantly, TXA did not increase the incidence of thromboembolic events (OR 2.22; 95% CI 0.47 to 10.43) and mortality (OR 0.60; 95% CI 0.13 to 2.76).

CONCLUSION

TXA safely reduces the need for blood transfusion in patients undergoing liver resection and transplantation.

Validation of McCluskey Index for Massive Blood Transfusion Prediction in Liver Transplantation

BACKGROUND

The McCluskey index has been used as a tool to predict massive bleeding (>6 red blood cells units) during orthotropic liver transplantation. The objective of this study is to verify its efficacy at our institution.

MATERIALS AND METHODS

Between May 1998 and December 2017, we performed 1216 orthotropic liver transplantations, of which 1016 had sufficient data registered with respect to hemoderivative transfusion. We divided these patients into groups based on the original study of McCluskey. This study was approved by the ethical committee of our Institution and was performed in accordance with the Declaration of Helsinki.

RESULTS

The mean Model for End-Stage Liver Disease score in the 4 groups was 7.5 (range, 7-8) for low risk; 13 (range, 3-32) for medium risk, 17 (range, 8-41) for high risk, and 25 (range, 11-36) for very high risk (P < .001). No significant differences were observed regarding body mass index or hospital stay. No differences have been found in the number of suboptimal donors among the groups. With respect to hemoderivative transfusions, we observed the following for red blood cells: 7 (range, 6-8) units for low risk; 5.5 (range, 0-74) for medium risk; 7 (range, 0-73) for high risk, and 12 (range, 5-30) for very high risk (P < .001) and transfusion of plasma: 12 (range, 10-15) units for low risk; 11 (range, 0-89) for medium risk; 14 (range, 0-76) for high risk, and 13 (range, 3-30) for very high risk (P = .001).

CONCLUSIONS

The McCluskey index is a good indicator of the risk of hemorrhage and hence the necessity of transfusion.

Hemoderivative Transfusion in Liver Transplantation: Comparison Between Recipients of Grafts From Brain Death Donors and Recipients of Uncontrolled Donors After Circulatory Death

INTRODUCTION

Intraoperative bleeding during liver transplantation has been correlated with a higher risk of morbidity and mortality and decrease in patient and graft survival.

MATERIALS AND METHODS

Between January 2006 and December 2016 we performed 783 orthotopic liver transplants. After applying exclusion criteria, we found liver grafts from donors after circulatory death (DCD, group A) were used in 69 patients and liver grafts from donors after brain death (group B) were used in 265 patients.

RESULTS

No difference was found in terms of sex, body mass index, Model for End-Stage Liver Disease score, indication for transplantation, intensive care unit stay, and Child-Pugh score. The mean transfusion of hemoderivates was as follows: red blood cell 9 (0-28) units in group A vs 6 (0-20) units in group B (P = .004) and fresh frozen plasma 10 (0-29) units in group A vs 9.5 (0-23) in group B (P = .000). The only 2 factors related to massive blood transfusion (>6 units of red blood cell) were uncontrolled DCD condition (odds ratio = 2.38; 95% confidence interval, 1.32-4.31; P = .004), and higher Model for End-Stage Liver Disease score (odds ratio = 2.63; 95% confidence interval, 1.53-4.55; P = .001). Survival at 1, 3, and 5 years was 81.3%, 70.2%, and 68.9% in group A vs 89%, 83.7%, and 78% in group B (P = .070).

CONCLUSION

The use of liver grafts from DCDs is associated with increased necessity of transfusion of hemoderivates in comparison with the use of liver grafts from donors after brain death.

Procedure-related bleeding risk in patients with cirrhosis and severe thrombocytopenia

BACKGROUND

Gaps of knowledge still exist about the potential association between severe thrombocytopenia and increased risk of procedure-associated bleeding in patients with liver disease.

METHODS

In this narrative review, we aimed at examining the association between procedure-related bleeding risk and platelet count in patients with cirrhosis and severe thrombocytopenia in various settings. We updated to 2020 a previously conducted literature search using MEDLINE/PubMed and EMBASE. The search string included clinical studies, adult patients with chronic liver disease and thrombocytopenia undergoing invasive procedures, any interventions and comparators, and haemorrhagic events of any severity as outcome.

RESULTS

The literature search identified 1276 unique publications, and 15 studies met the inclusion criteria and were analysed together with those identified by the previous search. Most of the new studies included in our analysis did not assess the association between post-procedural bleeding risk and platelet count alone in patients with chronic liver disease. Furthermore, some results could have been biased by prophylactic platelet transfusions. A few studies found that severe thrombocytopenia may be predictive of bleeding following percutaneous liver biopsy, dental extractions, percutaneous ablation of liver tumours and endoscopic polypectomy.

CONCLUSIONS

Currently available literature cannot support definitive conclusions about the appropriate target platelet counts to improve the risk of bleeding in cirrhotic patients who underwent invasive procedures; moreover, it showed enormous variability in the use of prophylactic platelet transfusions.

Machine Learning for the Prediction of Red Blood Cell Transfusion in Patients During or After Liver Transplantation Surgery

Aim: This study aimed to use machine learning algorithms to identify critical preoperative variables and predict the red blood cell (RBC) transfusion during or after liver transplantation surgery. Study Design and Methods: A total of 1,193 patients undergoing liver transplantation in three large tertiary hospitals in China were examined. Twenty-four preoperative variables were collected, including essential population characteristics, diagnosis, symptoms, and laboratory parameters. The cohort was randomly split into a train set (70%) and a validation set (30%). The Recursive Feature Elimination and eXtreme Gradient Boosting algorithms (XGBOOST) were used to select variables and build machine learning prediction models, respectively. Besides, seven other machine learning models and logistic regression were developed. The area under the receiver operating characteristic (AUROC) was used to compare the prediction performance of different models. The SHapley Additive exPlanations package was applied to interpret the XGBOOST model. Data from 31 patients at one of the hospitals were prospectively collected for model validation. Results: In this study, 72.1% of patients in the training set and 73.2% in the validation set underwent RBC transfusion during or after the surgery. Nine vital preoperative variables were finally selected, including the presence of portal hypertension, age, hemoglobin, diagnosis, direct bilirubin, activated partial thromboplastin time, globulin, aspartate aminotransferase, and alanine aminotransferase. The XGBOOST model presented significantly better predictive performance (AUROC: 0.813) than other models and also performed well in the prospective dataset (accuracy: 76.9%). Discussion: A model for predicting RBC transfusion during or after liver transplantation was successfully developed using a machine learning algorithm based on nine preoperative variables, which could guide high-risk patients to take appropriate preventive measures.

Thromboelastography does not reduce transfusion requirements in liver transplantation: A propensity score-matched study

STUDY OBJECTIVE

To compare total blood product requirements in liver transplantation (LT) assisted by thromboelastography (TEG) or conventional coagulation tests (CCTs).

DESIGN

Retrospective observational study.

SETTING

A tertiary care referral center for LT.

PATIENTS

Adult patients undergoing LT from deceased donor.

INTERVENTION

Hemostasis was monitored by TEG or CCTs and corresponding transfusion algorithms were adopted.

MEASUREMENTS

Number and types of blood products (red blood cells, RBC; fresh-frozen plasma, FFP; platelets, PLT) transfused from the beginning of surgery until the admission to the intensive care unit.

METHODS

We compared data retrospectively collected in 226 LTs, grouped according to the type of hemostasis monitoring (90 with TEG and 136 with CCTs, respectively). Confounding variables affecting transfusion needs (recipient age, sex, previous hepatocellular carcinoma surgery, Model for End Stage Liver Disease - MELD, baseline hemoglobin, fibrinogen, creatinine, veno-venous by pass, and trans-jugular intrahepatic portosystemic shunt) were managed by propensity score match (PSM).

MAIN RESULTS

The preliminary analysis showed that patients in the TEG group received fewer total blood products (RBC + FFP + PLT; p = 0.001, FFP (p = 0.001), and RBC (p = 0.001). After PSM, 89 CCT patients were selected and matched to the 90 TEG patients. CCT and TEG matched patients received similar amount of total blood products. In a subgroup of 39 patients in the top MELD quartile (MELD ≥25), the TEG use resulted in lower consumption of FFP units and total blood products. Nevertheless, due to the low number of patients, any meaningful conclusion could be achieved in this subgroup.

CONCLUSIONS

In our experience, TEG-guided transfusion in LT does not reduce the intraoperative blood product consumption. Further studies are warranted to assess an advantage for TEG in either the entire LT population or the high-MELD subgroup of patients.

Transfusion Status in Liver and Kidney Transplantation Recipients-Results from Nationwide Claims Database

BACKGROUND

This study analyzed the status and trends of transfusion and its associated factors among liver and kidney transplantation recipients.

METHODS

A total of 10,858 and 16,191 naïve liver or kidney transplantation recipients from 2008 to 2017 were identified through the National Health Insurance Service database. The prescription code for transfusion and the presence, number, and amount of each type of transfusion were noted. The odds ratios and 95% confidence intervals were determined to identify significant differences in transfusion and blood components by liver and kidney transplantation recipient characteristics.

RESULTS

In this study, 96.4% of liver recipients and 59.7% of kidney recipients received transfusions related to the transplantation operation, mostly platelet and fresh frozen plasma. Higher perioperative transfusion in women and declining transfusion rates from 2008 to 2017 were observed in both liver and kidney recipients. In liver recipients, the transfusion rate in those who received organs from deceased donors was much higher than that in those who received organs from living donors; however, the mortality rate according to transfusion was higher only in recipients of deceased donor organs. In kidney recipients, a higher mortality rate was observed in those receiving transfusion than that in patients without transfusion.

CONCLUSIONS

In Korea, the transfusion rates in liver and kidney recipients were relatively higher than those in other countries. Sociodemographic factors, especially sex and year of transplantation, were associated with transfusion in solid organ recipients, possibly as surrogates for other causal clinical factors.

The learning curve for piggyback liver transplantation: identifying factors challenging surgery

BACKGROUND

This study aimed to quantify the learning curve of piggyback liver transplantation and to identify factors that impact the operative time and blood transfusion during the learning curve.

METHODS

A retrospective review was performed on consecutive cases of patients' first piggyback liver transplantations that were performed by a single surgeon. The learning curve for the operative time was evaluated using the cumulative sum method.

RESULTS

There were 181, consecutive, first-time piggyback liver transplantations. The median operative time was 345 minutes (range: 180-745 minutes) with a median transfusion rate of 4 packed red blood cell units (range: 0-23 units). The cumulative sum learning curve identified 3 phases: an initial phase (1-70 piggyback liver transplantations), a plateau phase (71-101 piggyback liver transplantations), and a stable phase (102-181 piggyback liver transplantations). Over the 3 phases, there were significant decreases in the median duration of the surgery (388.8 vs 344.8 vs 326.9 minutes; P = .004, P = .0004, P ≤ .0001) and the number of red blood cell units transfused (6.00 vs 3.90 vs 3.71; P = .02, P = .79, P = .0006). Multivariable analysis identified that the following factors impacted the operative time: surgeon experience (P = .00006), previous upper abdominal surgery (P = .01), portocaval shunt fashioning (P = .0003), early portal section (P = .00001), multiple arterial graft reconstruction (P = .03), and the length of the retrohepatic inferior vena covered by segment 1 (P = .0006). Independent risk factors for increased blood loss were surgeon experience (P = .0001), previous upper abdominal surgery (P = .002), the retrohepatic inferior vena cava encirclement by segment 1 (P = .0001), severe portal hypertension (P = .01), early portal section (P = .001), and low prothrombin time (P = .00001).

CONCLUSION

Easily identifiable factors related to recipients (segment 1 morphology, previous upper abdominal surgery, severe portal hypertension) and to surgeon (operative experience, portocaval shunt fashioning, early portal section, and multiple arterial reconstructions) impact operative time and blood loss during the learning curve of piggyback liver transplantation. These factors can be used for grading the difficulties of liver transplantation to tailor the surgical strategy.

Validation of predictive models identifying patients at risk for massive transfusion during liver transplantation and their potential impact on blood bank resource utilization

BACKGROUND

Intraoperative massive transfusion (MT) is common during liver transplantation (LT). A predictive model of MT has the potential to improve use of blood bank resources.

STUDY DESIGN AND METHODS

Development and validation cohorts were identified among deceased-donor LT recipients from 2010 to 2016. A multivariable model of MT generated from the development cohort was validated with the validation cohort and refined using both cohorts. The combined cohort also validated the previously reported McCluskey risk index (McRI). A simple modified risk index (ModRI) was then created from the combined cohort. Finally, a method to translate model predictions to a population-specific blood allocation strategy was described and demonstrated for the study population.

RESULTS

Of the 403 patients, 60 (29.6%) in the development and 51 (25.5%) in the validation cohort met the definition for MT. The ModRI, derived from variables incorporated into multivariable model, ranged from 0 to 5, where 1 point each was assigned for hemoglobin level of less than 10 g/dL, platelet count of less than 100 × 10⁹ /dL, thromboelastography R interval of more than 6 minutes, simultaneous liver and kidney transplant and retransplantation, and a ModRI of more than 2 defined recipients at risk for MT. The multivariable model, McRI, and ModRI demonstrated good discrimination (c statistic [95% CI], 0.77 [0.70-0.84]; 0.69 [0.62-0.76]; and 0.72 [0.65-0.79], respectively, after correction for optimism). For blood allocation of 6 or 15 units of red blood cells (RBCs) based on risk of MT, the ModRI would prevent unnecessary crossmatching of 300 units of RBCs/100 transplants.

CONCLUSIONS

Risk indices of MT in LT can be effective for risk stratification and reducing unnecessary blood bank resource utilization.

Comparison of Coagulation Conditions in Patients With Liver Cirrhosis Due to Primary Sclerosing Cholangitis and Nonbiliary Causes of Cirrhosis Before Orthotopic Liver Transplant

OBJECTIVES

Orthotopic liver transplant can be accompanied by an obscure bleeding pattern in patients with severe hepatic malfunction. In the present study, coagulation conditions of patients with cirrhosis of the liver due to primary sclerosing cholangitis and nonbiliary causes of cirrhosis were compared using rotational thromboelastometry assays obtained before orthotopic liver transplant.

MATERIALS AND METHODS

This case control study analyzed patients who were candidates for orthotopic liver transplant from 2010 to 2016. Eighty patients with cirrhosis of the liver (40 patients with primary sclerosing cholangitis and 40 with nonbiliary causes of cirrhosis) were randomly selected and enrolled into the study. Patients received rotational thromboelastometry assays under anesthesia just before the start of the operation, and results were compared between the 2 patient groups.

RESULTS

Of 80 patients, 52 were men and 28 were women. In the assays, we found that maximum amplitudes in 10 and in 20 minutes and maximum clot firmness parameters were higher in patients with primary sclerosing cholangitis. The alpha angle and clot formation time were different in the intrinsic and extrinsic assay panels. In the intrinsic assay, we found clotting time to be shorter (P < .05). The average of all parameters in all 3 assays (intrinsic, extrinsic, and fibrinogen contribution) was lower in patients with nonbiliary causes of cirrhosis than in those with primary sclerosing cholangitis.

CONCLUSIONS

In contrast with previous studies that found that patients with primary sclerosing cholangitis are hypercoagulable, our study observed that they have normal coagulable results. Furthermore, we found that, although mean coagulation indexes in patients with primary sclerosing cholangitis were within normal ranges, in patients with nonbiliary causes of cirrhosis, these indexes were generally lower.

Liver Transplantation

The field of liver transplantation has changed since the MELD scoring system became the most widely used donor allocation tool. Due to the MELD-based allocation system, sicker patients with higher MELD scores are being transplanted. Persistent organ donor shortages remain a challenging issue, and as a result, the wait-list mortality is a persistent problem for most of the regions. This chapter focuses on deceased donor and live donor liver transplantation in patients with complications of portal hypertension. Special attention will also be placed on donor-recipient matching, perioperative management of transplant patients, and the impact of hepatic hemodynamics on transplantation.

Effects of Share 35 Policy on Liver Transplantation Outcomes for Patients With Nonalcoholic Steatohepatitis

BACKGROUND

To examine the temporal variation and outcomes of liver transplantation between pre- and post-Share 35 eras for patients with nonalcoholic steatohepatitis.

METHODS

A retrospective analysis was performed among 4380 patients with end-stage liver disease from the United Network for Organ Sharing database from 2009 to 2017 due to primary diagnosis of nonalcoholic steatohepatitis or cryptogenic cirrhosis with body mass index greater than 30. Cox regressions were used to model the effect of Share 35 policy on patient and graft survival comparing the first 3 years of Share 35 policy to an equivalent time period before.

RESULTS

The number of nonalcoholic steatohepatitis-related transplants increased from 232 (14.1%) in 2009 to 266 (20.5%) in 2017. In post-Share 35 era, average waitlist time and cold ischemic time decreased, while Model for End-Stage Liver Disease (MELD) scores increased with higher proportion of recipients having MELD ≥35. No significant difference in average length of hospitalization or survival was found after Share 35.

CONCLUSIONS

The Share 35 policy benefits patients with nonalcoholic steatohepatitis from reduced liver transplantation waiting time. It is also associated with comparable outcomes in 2 eras without increasing cold ischemic time or posttransplant length of hospitalization.

Quality Improvement in Transfusion Practice of Orthotopic Liver Transplantation Reduces Blood Utilization, Length of Hospital Stay, and Cost

OBJECTIVES

Orthotopic liver transplantation (OLT) can require substantial usage of blood products. Higher rates of transfusion have been associated with increased length of hospital stay, higher rates of infection, graft failure, and mortality. This study was a retrospective analysis to assess the impact of quality improvement interventions in OLT.

METHODS

Data collection included demographics, preoperative and intraoperative data, blood utilization, and cost data. Statistical analysis was performed using R software.

RESULTS

Total blood product utilization was reduced by approximately 50%. Statistically significant decreases were noted in blood product usage in the intraoperative and first 48-hour postoperative utilization, the number of OLTs using fewer than five RBC units, length of hospital stay, and cost.

CONCLUSIONS

This study showed successful implementation of quality improvement team interventions to reduce blood utilization during OLT. Reduced transfusion significantly correlated with decreased length of hospital stay and cost.

Association between viscoelastic tests-guided therapy with synthetic factor concentrates and allogenic blood transfusion in liver transplantation: a before-after study

Background

Perioperative bleeding and transfusion are important causes of morbidity and mortality in patients undergoing liver transplantation. The aim of this study is to assess whether viscoelastic tests-guided therapy with the use of synthetic factor concentrates impact transfusion rates of hemocomponents in adult patients undergoing liver transplantation.

Methods

This is an interventional before-after comparative study. Patients undergoing liver transplantation before the implementation of a protocol using thromboelastometry and synthetic factor concentrates were compared to patients after the implementation. Primary outcome was transfusion of any hemocomponents. Secondary outcomes included: transfusion of red blood cells (RBC), fresh frozen plasma (FFP), cryoprecipitate or platelets, clinical complications, length of stay and in-hospital mortality.

Results

A total of 183 patients were included in the control and 54 in the intervention phase. After propensity score matching, the proportion of patients receiving any transfusion of hemocomponents was lower in the intervention phase (37.0 vs 58.4%; OR, 0.42; 95% CI, 0.20–0.87; p = 0.019). Patients in the intervention phase received less RBC (30.2 vs 52.5%; OR, 0.21; 95% CI, 0.08–0.56; p = 0.002) and FFP (5.7 vs 27.3%; OR, 0.11; 95% CI, 0.03–0.43; p = 0.002). There was no difference regarding transfusion of cryoprecipitate and platelets, complications related to the procedure, hospital length of stay and mortality.

Conclusions

Use of a viscoelastic test-guided transfusion algorithm with the use of synthetic factor concentrates reduces the transfusion rates of allogenic blood in patients submitted to liver transplantation.

Trial registration

This trial was registered retrospectively on November 15th, 2018 – clinicaltrials.gov – Identifier: NCT03756948.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0664-8) contains supplementary material, which is available to authorized users.

Albumin-Bilirubin Score for Predicting Post-Transplant Complications Following Adult-to-Adult Living Donor Liver Transplantation

Background

Albumin-Bilirubin (ALBI) grade has been evaluated as an objective method to assess liver function and predict postoperative complications, particularly after hepatectomy in patients with hepatocellular carcinoma (HCC). However, ALBI grade was rarely used in evaluation in living donor liver transplantation (LDLT).

Material/Methods

Between March 2005 and November 2015, 272 consecutive patients undergoing right-lobe LDLT were enrolled in this study. According to the ALBI score used to evaluate recipients preoperatively, those patients were divided into 3 grades (I, II, and III). Demographic findings and the post-operative complication rates were collected and compared among groups.

Results

The proportions of massive blood cell transfusions were different among those 3 grades (p<0.05). The patients in grade III had a higher risk of bacterial pneumonia and early allograft dysfunction (EAD) compared to grade I (p=0.029 and p=0.038, respectively) and grade II (p=0.006 and p=0.007, respectively). The area under the receiver operating characteristic curve of ALBI, Child-Pugh, and MELD for predicting 30-day mortality were 0.702 (95% CI: 0.644–0.756), 0.669 (95% CI: 0.580–0.697, p=0.510, versus ALBI grade), and 0.540 (95% CI: 0.580–0.697, p=0.144, versus ALBI grade), respectively.

Conclusions

ALBI grade was a good index for predicting post-operative complications and had a predictive ability similar to those of the Child-Pugh classification and MELD score.

A data-driven patient blood management strategy in liver transplantation

BACKGROUND AND OBJECTIVES

Blood utilization during liver transplant has decreased, but remains highly variable due to many complex surgical and physiologic factors. Previous models attempted to predict utilization using preoperative variables to stratify cases into two usage groups, usually using entire blood units for measurement. We sought to develop a practical predictive model using specific transfusion volumes (in ml) to develop a data-driven patient blood management strategy.

MATERIALS AND METHODS

This is a retrospective evaluation of primary liver transplants at a single institution from 2013 to 2015. Multivariable analysis of preoperative recipient and donor factors was used to develop a model predictive of intraoperative red-blood-cell (pRBC) use.

RESULTS

Of 256 adult liver transplants, 207 patients had complete transfusion volume data for analysis. The median intraoperative allogeneic pRBC transfusion volume was 1250 ml, and the average was 1563 ± 1543 ml. Preoperative haemoglobin, spontaneous bacterial peritonitis, preoperative haemodialysis and preoperative international normalized ratio together yielded the strongest model predicting pRBC usage. When it predicted <1250 ml of pRBCs, all cases with 0 ml transfused were captured and only 8·6% of the time >1250 ml were used. This prediction had a sensitivity of 0·91 and a specificity of 0·89. If predicted usage was >2000 ml, 75% of the time blood loss exceeded 2000 ml.

CONCLUSION

Patients likely to require low or high pRBC transfusion volumes were identified with excellent accuracy using this predictive model at our institution. This model may help predict bleeding risk for each patient and facilitate optimized blood ordering.

The Coagulation Profile of End-Stage Liver Disease and Considerations for Intraoperative Management

The coagulopathy of end-stage liver disease results from a complex derangement in both anticoagulant and procoagulant processes. With even minor insults, cirrhotic patients experience either inappropriate bleeding or clotting, or even both simultaneously. The various phases of liver transplantation along with fluid and blood product administration may contribute to additional disturbances in coagulation. Thus, anesthetic management of patients undergoing liver transplantation to improve hemostasis and avoid inappropriate thrombosis in the perioperative environment can be challenging. To add to this challenge, traditional laboratory tests of coagulation are difficult to interpret in patients with end-stage liver disease. Viscoelastic coagulation tests such as thromboelastography (Haemonetics Corporation, Braintree, MA) and rotational thromboelastometry (TEM International, Munich, Germany) have helped to reduce transfusion of allogeneic blood products, especially fresh frozen plasma, but have also lead to the increased use of fibrinogen-containing products. In general, advancements in surgical techniques and anesthetic management have led to significant reduction in blood transfusion requirements during liver transplantation. Targeted transfusion protocols and pharmacologic prevention of fibrinolysis may further aid in the management of the complex coagulopathy of end-stage liver disease.

Preoperative thrombelastography maximum amplitude predicts massive transfusion in liver transplantation

BACKGROUND

Massive transfusion (MT) is frequently required during liver transplantation. Risk stratification of transplant patients at risk for MT is an appealing concept but remains poorly developed. Thrombelastography (TEG) has recently been shown to reduce mortality when used for trauma resuscitation. We hypothesize that preoperative TEG can be used to risk stratify patients for MT.

MATERIAL AND METHODS

Liver transplant patients had blood drawn before surgical incision and assayed via TEG. Preoperative TEG measurements were collected in addition to standard laboratory coagulation tests. TEG variables including R-time (reaction time), angle, maximum amplitude (MA), and LY30 (clot lysis 30 min after MA) were correlated to red blood cell units, plasma (fresh frozen plasma), cryoprecipitate, and platelets during the first 24 h after surgery and tested for their performance using a receiver-operating characteristic curve.

RESULTS

Twenty-eight patients were included in the analysis with a median Model for End-Stage Liver Disease score of 17; 36% received a MT. The TEG variables associated with MT (defined as ≥10 red blood cell units/24 h) were a low MA (P < 0.001) and low angle (P = 0.014). A high international normalized ratio of prothrombin time (P = 0.003) and low platelet count (P = 0.007) were also associated with MT. MA had the highest area under the curve (0.861) followed by international normalized ratio of prothrombin time (0.803). An MA of less than 47 mm has a sensitivity of 90% and specificity of 72% to predict a MT. MA was the only coagulation variable that correlated strongly to all blood products transfused.

CONCLUSIONS

TEG MA has a high predictability of MT during liver transplantation. The use of TEG preoperatively may help guide more cost effective blood bank preparation for this procedure as only a third of patients required a MT.

Critical care management of the patient with cirrhosis awaiting liver transplant in the intensive care unit

Patients with cirrhosis who are awaiting liver transplantation (LT) are at high risk for developing critical illnesses. Current liver allocation policies that dictate a "sickest first" approach coupled with a mismatch between need and availability of organs result in longer wait times, and thus, patients are becoming increasingly ill while awaiting organ transplantation. Even patients with well-compensated cirrhosis may suffer acute deterioration; the syndrome of acute-on-chronic liver failure (ACLF) results in multisystem organ dysfunction and a marked increase in associated short-term morbidity and mortality. For patients on transplant waiting lists, the development of multisystem organ failure may eliminate candidacy for transplant by virtue of being "too sick" to safely undergo transplantation surgery. The goals of intensive care management of patients suffering ACLF are to rapidly recognize and treat inciting events (eg, infection and bleeding) and to aggressively support failing organ systems to ensure that patients may successfully undergo LT. Management of the critically ill ACLF patient awaiting transplantation is best accomplished by multidisciplinary teams with expertise in critical care and transplant medicine. Such teams are well suited to address the needs of this unique patient population and to identify patients who may be too ill to proceed to transplantation surgery. The focus of this review is to identify the common complications of ACLF and to describe our approach management in critically ill patients awaiting LT in our centers. Liver Transplantation 23 1465-1476 2017 AASLD.

Development of a Predictive Model for Blood Transfusions and Bleeding During Liver Transplantation: An Observational Cohort Study

OBJECTIVE

Orthotopic liver transplantation (OLT) frequently is associated with major blood loss and considerable transfusion requirements. The goal of this study was to define the risk factors for multiple transfusions and major bleeding during OLT and to help identify higher risk patients that could benefit from targeted interventions.

DESIGN

OLTs were studied for this observational cohort study.

SETTING

Community hospital.

PARTICIPANTS

A total of 800 consecutive OLTs were studied.

INTERVENTION

No intervention.

MEASUREMENTS AND MAIN RESULTS

Baseline and intraoperative data were gathered. Multivariate logistic regression analyses were performed to find variables associated with 2 outcomes: transfusion of more than 2 units of red blood cells (RBC) and bleeding ≥900 mL. Two nomograms were developed to predict individual risks. The overall intraoperative RBC transfusion was 0.6 ± 1.4 units on average, and 61 surgeries (7.6%) received more than 2 units of RBC (4.5 ± 1.9). Some variables were associated with the outcomes: 5 were associated with transfusion of more than 2 units of RBC (patient's height, starting hemoglobin concentration, starting bilirubin value, the use of a phlebotomy, and central venous pressure [CVP] at the time of vena cava clamping) and 3 with blood loss of ≥900 mL (starting hemoglobin value, Child-Turcotte-Pugh score, and CVP at the time of vena cava clamping). Preclamping CVP showed the strongest association with both outcomes. Nomograms were developed to predict the individual OLT recipients' risk of requiring more than 2 units RBC and suffering from major bleeding. Among the variables associated with multiple RBC transfusions and major bleeding, 3 can lead to interventions: baseline hemoglobin value, the use of a phlebotomy, and the preclamping CVP.

CONCLUSION

Some variables were able to predict the risk of multiple transfusions and major bleeding in this low bleeding liver transplantation population. Further studies based on these variables should be done to better define the role of targeted interventions in higher risk liver transplant recipients.

Preoperative risk factors for intra-operative bleeding in pediatric liver transplantation

This study analyzes the preoperative risk factors for intra-operative bleeding in our recent series of pediatric LTs. Between November 2009 and November 2014, 84 consecutive isolated pediatric LTs were performed in 81 children. Potential preoperative predictive factors for bleeding, amount of intra-operative transfusions, postoperative course, and outcome were recorded. Cutoff point for intra-operative HBL was defined as intra-operative RBC transfusions ≥1 TBV. Twenty-six patients (31%) had intra-operative HBL. One-year patient survival after LT was 66.7% (CI 95%=[50.2-88.5]) in HBL patients and 83.8% (CI 95%=[74.6-94.1]) in the others (P=.054). Among 13 potential preoperative risk factors, three of them were identified as independent predictors of high intra-operative bleeding: abdominal surgical procedure(s) prior to LT, factor V level ≤30% before transplantation, and ex situ parenchymal transsection of the liver graft. Based on these findings, we propose a simple score to predict the individual hemorrhagic risk related to each patient and graft association. This score may help to better anticipate intra-operative bleeding and improve patient's management.

Massive haemorrhage in liver transplantation: Consequences, prediction and management

From its inception the success of liver transplantation has been associated with massive blood loss. Massive transfusion is classically defined as > 10 units of red blood cells within 24 h, but describing transfusion rates over a shorter period of time may reduce the potential for survival bias. Both massive haemorrhage and transfusion are associated with increased risk of mortality and morbidity (need for dialysis/surgical site infection) following liver transplantation although causality is difficult to prove due to the observational design of most trials. The blood loss associated with liver transplantation is multifactorial. Portal hypertension secondary to cirrhosis results in extensive collateral circulation, which can bleed during hepatectomy particular if portal pressures are increased. Avoiding volume loading and maintenance of a low central venous pressure together with the use of vasopressors have been shown to reduce blood loss and transfusion during liver transplantation, but may increase the risk of renal impairment post-operatively. Coagulation defects may be present pre-transplant, but haemostasis is often re-balanced due to a deficit in both pro- and anti-coagulation factors. Further derangement of haemostasis may develop in the anhepatic and neohepatic phases due to absent hepatic metabolic function, hyperfibrinolysis and platelet sequestration in the donor liver. Point-of-care tests of coagulation such as the viscoelastic tests rotation thromboelastometry/thromboelastometry allow and more accurate and rapid assessment of these derangements in coagulation and guide the use of factor replacement and antifibrinolytics. Transfusion protocols guided by these tests have been shown to reduce transfusion rates compared with conventional coagulation tests, but have not shown improvements in mortality or morbidity. Pre-operative factors associated with massive transfusion include previous surgery, re-do transplantation, the aetiology and severity of liver disease. Intra-operatively the use of piggy-back technique and avoiding veno-veno bypass has been shown to reduced blood loss.

Hemostatic balance in patients with liver cirrhosis: Report of a consensus conference

Patients with cirrhosis present with hemostatic alterations secondary to reduced availability of pro-coagulant and anti-coagulant factors. The net effect of these changes is a rebalanced hemostatic system. The Italian Association of the Study of the Liver (AISF) and the Italian Society of Internal Medicine (SIMI) promoted a consensus conference on the hemostatic balance in patients with cirrhosis. The consensus process started with the review of the literature by a scientific board of experts and ended with a formal consensus meeting in Rome in December 2014. The statements were graded according to quality of evidence and strength of recommendations, and approved by an independent jury. The statements presented here highlight strengths and weaknesses of current laboratory tests to assess bleeding and thrombotic risk in cirrhotic patients, the pathophysiology of hemostatic perturbations in this condition, and outline the optimal management of bleeding and thrombosis in patients with liver cirrhosis.

Reducing transfusion requirements in liver transplantation

Liver transplantation (LT) was historically associated with massive blood loss and transfusion. Over the past two decades transfusion requirements have reduced dramatically and increasingly transfusion-free transplantation is a reality. Both bleeding and transfusion are associated with adverse outcomes in LT. Minimising bleeding and reducing unnecessary transfusions are therefore key goals in the perioperative period. As the understanding of the causes of bleeding has evolved so too have techniques to minimize or reduce the impact of blood loss. Surgical “piggyback” techniques, anaesthetic low central venous pressure and haemodilution strategies and the use of autologous cell salvage, point of care monitoring and targeted correction of coagulopathy, particularly through use of factor concentrates, have all contributed to declining reliance on allogenic blood products. Pre-emptive management of preoperative anaemia and adoption of more restrictive transfusion thresholds is increasingly common as patient blood management (PBM) gains momentum. Despite progress, increasing use of marginal grafts and transplantation of sicker recipients will continue to present new challenges in bleeding and transfusion management. Variation in practice across different centres and within the literature demonstrates the current lack of clear transfusion guidance. In this article we summarise the causes and predictors of bleeding and present the evidence for a variety of PBM strategies in LT.

Reduced Transfusion During OLT by POC Coagulation Management and TEG Functional Fibrinogen: A Retrospective Observational Study

Patients undergoing orthotopic liver transplantation are at high risk of bleeding complications. Several Authors have shown that thromboelastography (TEG)-based coagulation management and the administration of fibrinogen concentrate reduce the need for blood transfusion.

METHODS

We conducted a single-center, retrospective cohort observational study (Modena Polyclinic, Italy) on 386 consecutive patients undergoing liver transplantation. We assessed the impact on resource consumption and patient survival after the introduction of a new TEG-based transfusion algorithm, requiring also the introduction of the fibrinogen functional thromboelastography test and a maximum amplitude of functional fibrinogen thromboelastography transfusion cutoff (7 mm) to direct in administering fibrinogen (2012-2014, n = 118) compared with a purely TEG-based algorithm previously used (2005-2011, n = 268).

RESULTS

After 2012, there was a significant decrease in the use of homologous blood (1502 ± 1376 vs 794 ± 717 mL, P < 0.001), fresh frozen plasma (537 ± 798 vs 98 ± 375 mL, P < 0.001), and platelets (158 ± 280 vs 75 ± 148 mL, P < 0.005), whereas the use of fibrinogen increased (0.1 ± 0.5 vs 1.4 ± 1.8 g, P < 0.001). There were no significant differences in 30-day and 6-month survival between the 2 groups.

CONCLUSIONS

The implementation of a new coagulation management method featuring the addition of the fibrinogen functional thromboelastography test to the TEG test according to an algorithm which provides for the administration of fibrinogen has helped in reducing the need for transfusion in patients undergoing liver transplantation with no impact on their survival.