Survival Predictors in Liver Transplantation: Time-Varying Effect of Red Blood Cell Transfusion

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.

Preoperative fibrinogen level and blood transfusions in liver transplantation: A systematic review

BACKGROUND

Orthotopic liver transplantation (OLT) is a major surgery often associated with significant bleeding. We conducted a systematic review to explore the association between preoperative fibrinogen level and intraoperative blood products transfusion, blood loss and clinical outcomes in patients undergoing OLT.

METHODS

We included observational studies conducted in patients undergoing an OLT mostly for end-stage liver disease that reported an association between the preoperative fibrinogen level and our outcomes of interest. Our primary outcome was the intraoperative red blood cell (RBC) transfusion requirements. Our secondary outcomes were intraoperative blood loss, intraoperative transfusion of any blood product, postoperative RBC transfusion, postoperative thrombotic or hemorrhagic complications, and mortality. We used a standardized search strategy. We reported our results mostly descriptively but conducted meta-analyses using random-effect models when judged feasible.

RESULTS

We selected 24 cohort studies reporting at least one of our outcomes. We found that a high preoperative fibrinogen level was associated with fewer intraoperative RBC and other blood products transfusions, and lower blood loss. We also found a lower overall survival in patients with a higher fibrinogen level (pooled hazard ratio [95% CI] of 1.50 [1.23 to 1.84]; 5 studies, n = 1012, I2 = 48%). Only one study formally explored a fibrinogen level threshold effect. Overall, reporting was heterogeneous, and risk of bias was variable mostly because of uncontrolled confounding.

CONCLUSION

A higher preoperative fibrinogen level was associated with fewer intraoperative RBC and other blood products transfusions, lower blood loss, and higher mortality. Further studies may help clarify observed associations and inform guidelines.

Perioperative clinical practice in liver transplantation: a cross-sectional survey

PURPOSE

The objective of this study was to describe some components of the perioperative practice in liver transplantation as reported by clinicians.

METHODS

We conducted a cross-sectional clinical practice survey using an online instrument containing questions on selected themes related to the perioperative care of liver transplant recipients. We sent email invitations to Canadian anesthesiologists, Canadian surgeons, and French anesthesiologists specialized in liver transplantation. We used five-point Likert-type scales (from "never" to "always") and numerical or categorical answers. Results are presented as medians or proportions.

RESULTS

We obtained answers from 130 participants (estimated response rate of 71% in Canada and 26% in France). Respondents reported rarely using transesophageal echocardiography routinely but often using it for hemodynamic instability, often using an intraoperative goal-directed hemodynamic management strategy, and never using a phlebotomy (medians from ordinal scales). Fifty-nine percent of respondents reported using a restrictive fluid management strategy to manage hemodynamic instability during the dissection phase. Forty-two percent and 15% of respondents reported using viscoelastic tests to guide intraoperative and postoperative transfusions, respectively. Fifty-four percent of respondents reported not pre-emptively treating preoperative coagulations disturbances, and 91% reported treating them intraoperatively only when bleeding was significant. Most respondents (48-64%) did not have an opinion on the maximal graft ischemic times. Forty-seven percent of respondents reported that a piggyback technique was the preferred vena cava anastomosis approach.

CONCLUSION

Different interventions were reported to be used regarding most components of perioperative care in liver transplantation. Our results suggest that significant equipoise exists on the optimal perioperative management of this population.

A Retrospective Study of the Role of Perioperative Serum Albumin and the Albumin-Bilirubin Grade in Predicting Post-Liver Transplant Length of Stay

INTRODUCTION

Serum albumin's association with liver transplant outcomes has been investigated with mixed findings. This study aimed to evaluate perioperative albumin level, independently and as part of the albumin-bilirubin (ALBI) grade, as a predictor of post-liver transplant hospital and intensive care unit (ICU) length of stay (LOS).

METHODS

Adult liver-only transplant recipients at our institution from September 2011 to May 2019 were included in this retrospective study. Repeat transplants were excluded. Demographic, laboratory, and hospital course data were extracted from an institutional data warehouse. Negative binomial regression was used to assess the association of LOS with ALBI grade, age, BMI, ASA score, Elixhauser comorbidity index, MELD-Na, warm ischemia time, units of platelets and cryoprecipitate transfused, and preoperative serum albumin.

RESULTS

Six hundred and sixty-three liver transplant recipients met inclusion criteria. The median preoperative serum albumin was 3.1 [2.6-3.6] g/dL. The median postoperative ICU and hospital LOS were 3.8 [2.4-6.8] and 12 [8-20] days, respectively. Preoperative serum albumin predicted hospital but not ICU LOS (ratio .9 [95% confidence interval (CI) .84-.99], P = .03, hospital LOS vs ratio .92 [95% CI 0.84-1.02], P = .10, ICU LOS). For patients with MELD-Na ≤ 20, ALBI grade-3 predicted longer hospital and ICU LOS (ratio 1.40 [95% CI 1.18-1.66], P < .001, hospital LOS vs ratio 1.62 [95% CI 1.32-1.99], P < .001, ICU LOS). These associations were not significant for patients with MELD-Na > 20.

CONCLUSIONS

Serum albumin predicted post-liver transplant hospital LOS. ALBI grade-3 predicted increased hospital and ICU LOS in low MELD-Na recipients.

Intraoperative transfusion management, antifibrinolytic therapy, coagulation monitoring and the impact on short-term outcomes after liver transplantation-A systematic review of the literature and expert panel recommendations

BACKGROUND

Liver transplantation (LT) is frequently complicated by coagulopathy associated with end-stage liver disease (ESLD), that is, often multifactorial.

OBJECTIVES

The objective of this systematic review was to identify evidence based intraoperative transfusion and coagulation management strategies that improve immediate and short-term outcomes after LT.

METHODS

PRISMA-guidelines and GRADE-approach were followed. Three subquestions were formulated. (Q); Q1: transfusion management; Q2: antifibrinolytic therapy; and Q3: coagulation monitoring.

RESULTS

Sixteen studies were included for Q1, six for Q2, and 10 for Q3. Q1: PRBC and platelet transfusions were associated with higher mortality. The use of prothrombin complex concentrate (PCC) and fibrinogen concentrate (FC) were not associated with reductions in intraoperative transfusion or increased thrombotic events. The use of cell salvage was not associated with hepatocellular carcinoma (HCC) recurrence or mortality. Cell salvage and transfusion education significantly decreased blood product transfusions. Q2: Epsilon-aminocaproic acid (EACA) and tranexamic acid (TXA) were not associated with decreased blood product transfusion, improvements in patient or graft survival, or increases in thrombotic events. Q3: Viscoelastic testing (VET) was associated with decreased allogeneic blood product transfusion compared to conventional coagulation tests (CCT) and is likely to be cost-effective. Coagulation management guided by VET may be associated with increases in FC and PCC use.

CONCLUSION

Q1: A specific blood product transfusion practice is not recommended (QOE; low | Recommendation; weak). Cell salvage and educational interventions are recommended (QOE: low | Grade of Recommendation: moderate). Q2: The routine use of antifibrinolytics is not recommended (QOE; low | Recommendation; weak). Q3: The use of VET is recommended (QOE; low-moderate | Recommendation; strong).

Intraoperative phlebotomies and bleeding in liver transplantation: a historical cohort study and causal analysis

BACKGROUND

Liver transplantation is associated with major bleeding and red blood cell (RBC) transfusions. No well-designed causal analysis on interventions used to reduce transfusions, such as an intraoperative phlebotomy, has been conducted in this population.

METHODS

We conducted a historical cohort study among liver transplantations performed from July 2008 to January 2021 in a Canadian centre. The exposure was intraoperative phlebotomy. The outcomes were blood loss, perioperative RBC transfusions (intraoperative and up to 48 hr after surgery), intraoperative RBC transfusions, and one-year survival. We estimated marginal multiplicative factors (MFs), risk differences (RDs), and hazard ratios by inverse probability of treatment weighting both among treated patients and the whole population. Estimates are reported with 95% confidence intervals (CIs).

RESULTS

We included 679 patients undergoing liver transplantations of which 365 (54%) received an intraoperative phlebotomy. A phlebotomy did not reduce bleeding, transfusion risks, or mortality when estimated among the treated but reduced bleeding and transfusion risks when estimated among the whole population (MF, 0.85; 95% CI, 0.72 to 0.99; perioperative RD, -15.2%; 95% CI, -26.1 to -0.8; intraoperative RD, -14.7%; 95% CI, -23.2 to -2.8). In a subgroup analysis on 584 patients with end-stage liver disease, slightly larger effects were observed on both transfusion risks when estimated among the whole population while beneficial effects were observed on the intraoperative transfusion risk when estimated among the treated population.

CONCLUSION

The use of intraoperative phlebotomy was not consistently associated with better outcomes in all targets of inference but may improve outcomes among the whole population.

STUDY REGISTRATION

www.

CLINICALTRIALS

gov (NCT04826666); registered 1 April 2021.

Survival Impact of Perioperative Red Blood Cell Transfusion During Pancreatectomy in Patients With Pancreatic Ductal Adenocarcinoma: A Propensity Score Matching Analysis

OBJECTIVES

The aim of this study was to show the real impact of perioperative red blood cell transfusion (PBT) on prognosis in patients who underwent pancreatectomy for pancreatic ductal adenocarcinoma.

METHODS

Patients who underwent pancreatectomy between 2004 and 2018 were enrolled. Short- and long-term outcomes in patients who received PBT (PBT group) were compared with those who did not (non-PBT group).

RESULTS

From a total of 197 patients, 55 (27.9%) received PBT, and 142 (72.1%) did not. The PBT group displayed a higher level of carbohydrate antigen 19-9 (P = 0.02), larger tumor size (P < 0.001), and a higher rate of lymph node metastasis (P = 0.02), and underwent more frequent pancreaticoduodenectomy (P < 0.001) and portal vein resection (P < 0.001). Before matching, recurrence-free survival (RFS) and overall survival (OS) in the PBT group were significantly worse than the non-PBT group (RFS: hazard ratio [HR], 1.73 [P = 0.002]; OS: HR, 2.06 [P < 0.001]). After matching, RFS and OS in the PBT group were not significantly different from the non-PBT group (RFS: HR, 1.44 [P = 0.15]; OS: HR, 1.53 [P = 0.11]).

CONCLUSIONS

Our results show that PBT has no survival impact in patients who underwent pancreatectomy for pancreatic ductal adenocarcinoma.

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.

Assessment of the Learning Process After Introducing a New Liver Transplantation Procedure in a Center With Extensive Experience in Kidney Transplantation

BACKGROUND

Liver transplantation (LTx) is one of the most complex transplant procedures. The aim of the present study was to determine whether the learning process can be observed after the introduction of LTx in a center with extensive previous experience in renal transplantation.

METHODS

This retrospective analysis included 264 primary LTx procedures performed with the piggyback technique (2005-2016). The procedures were divided into 4 equal groups. The characteristics of the recipients, data related to the surgery, and the postoperative course and complications were analyzed.

RESULTS

We observed a significant reduction in surgical time and in the anhepatic phase duration between Group 1 and the other groups (median surgical time was 455 minutes vs 415 minutes, 410 minutes and 387 minutes, respectively, P < .05; median anhepatic phase duration was 75 min vs 60 min, 62 min, 60 min, respectively, P < .05). There was a decrease in the number of transfused blood units (median in Group 1 of 6 packs vs 3 packs in Group 4, P < .05) and a decrease in blood recovered from the operating field using the Cell Saver system (median in Group 1 of 1570 mL vs 1057 mL, 1123 mL, and 1045 mL, respectively, P < .05). A significant reduction in the number of hemorrhages was found (1.5% in Group 4 vs 13.6%, 10.6%, and 7.6% in the other groups P < .05). The remaining studied parameters were not statistically significant.

CONCLUSIONS

Extensive previous transplantation experience affected the lack of typical features of the learning process.

Transfusion Medicine and Coagulation Management in Organ Transplantation

Organ transplantation recipients present unusual challenges with regard to blood transfusion. Although this patient population requires a larger proportion of blood product resources, liberal transfusion of allogeneic blood products can lead to a plethora of complications. Recent trends suggest that efforts to minimize bleeding, conserve products, and target transfusion to specific deficits and needs are increasingly becoming the standard practice; these must all occur with optimization of graft function and preservation in mind. With newer monitoring modalities and factor concentrates, the approach toward transfusion and bleeding in organ transplantation has rapidly improved in recent years.