Operative parameters that predict the outcomes of hepatic transplantation

Comprehensive Approach to Assessment of Liver Viability During Normothermic Machine Perfusion

Liver transplantation is the most effective treatment of advanced liver disease, and the use of extended criteria donor organs has broadened the source of available livers. Although normothermic machine perfusion (NMP) has become a useful tool in liver transplantation, there are no consistent criteria that can be used to evaluate the viability of livers during NMP. This review summarizes the criteria, indicators, and methods used to evaluate liver viability during NMP. The shape, appearance, and hemodynamics of the liver can be analyzed at a macroscopic level, while markers of liver injury, indicators of liver and bile duct function, and other relevant indicators can be evaluated by biochemical analysis. The liver can also be assessed by tissue biopsy at the microscopic level. Novel methods for assessment of liver viability are introduced. The limitations of evaluating liver viability during NMP are discussed and suggestions for future clinical practice are provided.

Characteristics and Outcomes of Liver Transplantation Recipients after Tranexamic Acid Treatment and Platelet Transfusion: A Retrospective Single-Centre Experience

Background and Objectives: Patients undergoing liver transplantation (LT) often require increased blood product transfusion due to pre-existing coagulopathy and intraoperative fibrinolysis. Strategies to minimise intraoperative bleeding and subsequent blood product requirements include platelet transfusion and tranexamic acid (TXA). Prophylactic TXA administration has been shown to reduce bleeding and blood product requirements intraoperatively. However, its clinical use is still debated. The aim of this study was to report on a single-centre practice and analyse clinical characteristics and outcomes of LT recipients according to intraoperative treatment of TXA or platelet transfusion. Materials and Methods: This was a retrospective observational cohort study in which we reviewed 162 patients' records. Characteristics, intraoperative requirement of blood products, postoperative development of thrombosis and outcomes were compared between patients without or with intraoperative TXA treatment and without or with platelet transfusion. Results: Intraoperative treatment of TXA and platelets was 53% and 57.40%, respectively. Patients who required intraoperative administration of TXA or platelet transfusion also required more transfusion of blood products. Neither TXA nor platelet transfusion were associated with increased postoperative development of hepatic artery and portal vein thrombosis, 90-day mortality or graft loss. There was a significant increase in the median length of intensive care unit (ICU) stay in those who received platelet transfusion only (2.00 vs. 3.00 days; p = 0.021). Time to extubate was significantly different in both those who required TXA and platelet transfusion intraoperatively. Conclusions: Our analysis indicates that LT recipients still required copious intraoperative transfusion of blood products, despite the use of intraoperative TXA and platelets. Our findings have important implications for current transfusion practice in LT recipients and may guide clinicians to act upon these findings, which will support global efforts to encourage a wider use of TXA to reduce transfusion requirements, including platelets.

The learning curve of deceased donor liver transplant during fellowship training

Liver transplantation (LT) is a complex operation that most transplant surgeons learn in fellowship. Training varies as there is lack of objective data that can be used to standardize teaching. We performed a retrospective review of our adult LT database with aim of looking at fellow's experience. Using American Society of Transplant Surgery cutoff of, at least 45 LT during fellowship, data for first 45 LT were compared to LT 45-90. Fellow's cases were also clustered in sequential groups of 15 LT and analyzed to estimate the learning curve (LC). Comparison of LT 1-45 with LT 46-90 showed significantly lower total operative times (TOT) (324 vs. 344 min) and warm ischemia times (WIT) (28 vs. 31 min) in the 45-90 group. Rates of biliary complications (23.8% vs. 16.4%) and bile leaks alone (10.3% vs. 5.5%) were significantly higher for first 45 LT. Analysis of fellows experience in sequential clusters of 15 LT showed decreasing TOT, WIT, biliary complications and rates of unplanned return to the OR with progression of fellowship. This study validates the current ASTS requirement of at least 45 LT. LC generated using these data can help individualize training and optimize outcomes through identification of areas in need of improvement.

Assessment and Transplantation of Orphan Donor Livers: A Back-to-Base Approach to Normothermic Machine Perfusion

Globally, a large proportion of donor livers are discarded due to concerns over inadequate organ quality. Normothermic machine perfusion (NMP) allows for hepatocellular and biliary viability assessment prior to transplantation and might therefore enable the safe use of these orphan donor livers. We describe here the first Australasian experience of NMP-preserved liver transplants using a 'back-to-base' approach, where NMP was commenced at the recipient hospital following initial static cold storage. In the preclinical phase, 10 human donor livers declined for transplantation (7 from donation after circulatory death [DCD] and 3 from donation after brain death [DBD]) were perfused using a custom-made NMP setup. Subsequently, 10 orphan donor livers (5 from DCD and 5 from DBD) underwent NMP and viability assessment on the OrganOx metra device (OrganOx Limited, Oxford, United Kingdom). Both hepatocellular and biliary viability criteria were used. The median donor risk index was 1.53 (1.16-1.71), and the median recipient Model for End-Stage Liver Disease score was 17 (11-21). In the preclinical phase, 'back-to-base' NMP was deemed suitable and feasible. In the clinical phase, each graft met predefined criteria for implantation during NMP and was subsequently transplanted. Five (50%) recipients developed early allograft dysfunction based on peak aspartate aminotransferase. To date, all grafts function satisfactorily, and none of the 5 recipients who received a DCD liver have developed cholangiopathy. The OrganOx metra using a back-to-base approach has enabled the safe use of 10 high-risk orphan donor livers with 100% 6-month patient and graft survival. NMP improved surgeon confidence to use orphan donor livers and has enabled a safe expansion of the donor pool.

Human Leukocyte Antigen Class I Antibodies and Response to Platelet Transfusion in Patients Undergoing Liver Transplantation

BACKGROUND

Patients undergoing liver transplantation (LT) frequently receive platelet transfusion (PLT) to minimize their risk of hemorrhage. Alloimmunization to platelets may lead to refractoriness to PLT. Data on the implications of platelet alloimmunization in patients undergoing LT remain limited. We examined the effect of human leukocyte antigen class I (HLA-I) antibodies on PLT refractoriness and short-term outcomes after LT.

METHODS

Peritransplant clinical and PLT factors were reviewed for all adult liver or simultaneous liver-kidney transplantations from 2012 to 2017. Sensitized patients (SE) with pretransplant HLA-I calculated panel-reactive antibody ≥20% were compared with unsensitized patients (US) with calculated panel-reactive antibody <20%. The mean follow-up was 21.4 mo.

RESULTS

Alloimmunization was observed in 39% of the study cohort. SE (n = 28) received 272 PLTs, and US (n = 44) received 246 PLTs. History of pregnancy was higher among SE than US (P < 0.01); otherwise, both groups had similar clinical characteristics. SE had higher rates of PLT refractoriness (66% versus 47%; P < 0.01) than US. The mean platelet corrected count increment was lower among SE compared with US up to 100 min after PLT (P < 0.05). Alloimmunization and simultaneous liver-kidney transplantation independently predicted refractoriness on multivariate logistic regression (P < 0.05). Early allograft rejection and patient survival rates were comparable for both groups.

CONCLUSIONS

LT patients experienced high rates of HLA-I alloimmunization and PLT refractoriness. SE had higher rates of refractoriness and lower mean corrected count increment after transfusion compared with US. Our study suggests that further research to evaluate the utility of HLA-matched PLTs in HLA-I alloimmunized LT patients is warranted.

Effects of Hepatic Ischemia-Reperfusion Injuries and NRF2 on Transcriptional Activities of Bile Transporters in Rats

BACKGROUND

The effect of hepatic ischemia-reperfusion injury (IRI) on bile transporter (BT) gene expression is unknown. We hypothesized that abnormal expression of BTs during hepatic IRI is dependent on nuclear factor erythroid 2-related factor 2 (NRF2), which contributes to the cholestasis after reperfusion.

METHODS

Sham surgery and short (60 min) or long (90 min) periods of warm ischemia time (WIT) with or without reperfusion for 24 h were applied to wild-type Sprague-Dawley rats and Nrf2 knockout rats (n = 5 per group). At each stage of IRI, the serum levels of aminotransferase, total bilirubin, and bile acids were measured. In addition, hepatic tissue was sampled to determine the histologic score of IRI (Suzuki score), measure adenosine triphosphate (ATP), and identify the quantitative real-time polymerase chain reactions of BTs (Oatp1, Ntcp, Mrp2, Bsep, and Mrp3).

RESULTS

In short periods of WIT, BT expression increased during the ischemia stage and returned to the baseline after reperfusion. However, in long periods of WIT, BT expression did not increase after ischemia and decreased further after reperfusion. Short WIT did not increase BT expression in Nrf2 knockout animals. The level of BT expression was correlated with the Suzuki score, the serum levels of aminotransferase, bilirubin, and bile acids, and tissue ATP level. Stepwise multiple regression analysis derived equations to predict the Suzuki score (R² = 76.8, P < 0.001), serum total bilirubin (R² = 61.2, P < 0.001), and tissue ATP (R² = 61.1, P < 0.001).

CONCLUSIONS

Short WIT induces the transcriptional activities of BT, whereas long WIT depresses them, and the effect was blunted by Nrf2 knockout status. BT expression can be considered a surrogate marker for hepatic IRI.

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.

Time spent in hospital after liver transplantation: Effects of primary liver disease and comorbidity

AIM

To explore the effect of primary liver disease and comorbidities on transplant length of stay (TLOS) and LOS in later admissions in the first two years after liver transplantation (LLOS).

METHODS

A linked United Kingdom Liver Transplant Audit - Hospital Episode Statistics database of patients who received a first adult liver transplant between 1997 and 2010 in England was analysed. Patients who died within the first two years were excluded from the primary analysis, but a sensitivity analysis was also performed including all patients. Multivariable linear regression was used to evaluate the impact of primary liver disease and comorbidities on TLOS and LLOS.

RESULTS

In 3772 patients, the mean (95%CI) TLOS was 24.8 (24.2 to 25.5) d, and the mean LLOS was 24.2 (22.9 to 25.5) d. Compared to patients with cancer, we found that the largest difference in TLOS was seen for acute hepatic failure group (6.1 d; 2.8 to 9.4) and the largest increase in LLOS was seen for other liver disease group (14.8 d; 8.1 to 21.5). Patients with cardiovascular disease had 8.5 d (5.7 to 11.3) longer TLOS and 6.0 d (0.2 to 11.9) longer LLOS, compare to those without. Patients with congestive cardiac failure had 7.6 d longer TLOS than those without. Other comorbidities did not significantly increase TLOS nor LLOS.

CONCLUSION

The time patients spent in hospital varied according to their primary liver disease and some comorbidities. Time spent in hospital of patients with cancer was relatively short compared to most other indications. Cardiovascular disease and congestive cardiac failure were the comorbidities with a strong impact on increased LOS.

Postoperative Insulin-Like Growth Factor 1 Levels Reflect the Graft's Function and Predict Survival after Liver Transplantation

Background

The reduction of insulin-like growth factor 1 (IGF-1) plasma levels is associated with the degree of liver dysfunction and mortality in cirrhotic patients. However, little research is available on the recovery of the IGF-1 level and its prognostic role after liver transplantation (LT).

Methods

From April 2010 to May 2011, 31 patients were prospectively enrolled (25/6 M/F; mean age±SEM: 55.2±1.4 years), and IGF-1 serum levels were assessed preoperatively and at 15, 30, 90, 180 and 365 days after transplantation. The influence of the donor and recipient characteristics (age, use of extended criteria donor grafts, D-MELD and incidence of early allograft dysfunction) on hormonal concentration was analyzed. The prognostic role of IGF-1 level on patient survival and its correlation with routine liver function tests were also investigated.

Results

All patients showed low preoperative IGF-1 levels (mean±SEM: 29.5±2.1), and on postoperative day 15, a significant increase in the IGF-1 plasma level was observed (102.7±11.7 ng/ml; p<0.0001). During the first year after LT, the IGF-1 concentration remained significantly lower in recipients transplanted with older donors (>65 years) or extended criteria donor grafts. An inverse correlation between IGF-1 and bilirubin serum levels at day 15 (r = -0.3924, p = 0.0320) and 30 (r = -0.3894, p = 0.0368) was found. After multivariate analysis, early (within 15 days) IGF-1 normalization [Exp(b) = 3.913; p = 0.0484] was the only prognostic factor associated with an increased 3-year survival rate.

Conclusion

IGF-1 postoperative levels are correlated with the graft’s quality and reflect liver function. Early IGF-1 recovery is associated with a higher 3-year survival rate after LT.

Thrombocytopenia, Platelet Transfusion, and Outcome Following Liver Transplantation

Thrombocytopenia affects patients undergoing liver transplantation. Intraoperative platelet transfusion has been shown to independently influence survival after liver transplantation at 1 and 5 years. We examined the impact of thrombocytopenia and intraoperative platelet transfusion on short-term graft and overall survival after orthotopic liver transplantation (OLT). A total of 399 patients undergoing first OLT were studied. Graft and overall survival in patients with different degrees of thrombocytopenia and with or without intraoperative platelet transfusion were described. The degree of thrombocytopenia prior to OLT did not affect graft or overall survival after transplant. However, graft survival in patients receiving platelets was significantly reduced at 1 year (P= .023) but not at 90 days (P= .093). Overall survival was significantly reduced at both 90 days (P= .040) and 1 year (P= .037) in patients receiving platelets. We conclude that a consistently lower graft and overall survival were observed in patients receiving intraoperative platelet transfusion.

Criteria for viability assessment of discarded human donor livers during ex vivo normothermic machine perfusion

Although normothermic machine perfusion of donor livers may allow assessment of graft viability prior to transplantation, there are currently no data on what would be a good parameter of graft viability. To determine whether bile production is a suitable biomarker that can be used to discriminate viable from non-viable livers we have studied functional performance as well as biochemical and histological evidence of hepatobiliary injury during ex vivo normothermic machine perfusion of human donor livers. After a median duration of cold storage of 6.5 h, twelve extended criteria human donor livers that were declined for transplantation were ex vivo perfused for 6 h at 37 °C with an oxygenated solution based on red blood cells and plasma, using pressure controlled pulsatile perfusion of the hepatic artery and continuous portal perfusion. During perfusion, two patterns of bile flow were identified: (1) steadily increasing bile production, resulting in a cumulative output of ≥ 30 g after 6 h (high bile output group), and (2) a cumulative bile production <20 g in 6 h (low bile output group). Concentrations of transaminases and potassium in the perfusion fluid were significantly higher in the low bile output group, compared to the high bile output group. Biliary concentrations of bilirubin and bicarbonate were respectively 4 times and 2 times higher in the high bile output group. Livers in the low bile output group displayed more signs of hepatic necrosis and venous congestion, compared to the high bile output group. In conclusion, bile production could be an easily assessable biomarker of hepatic viability during ex vivo machine perfusion of human donor livers. It could potentially be used to identify extended criteria livers that are suitable for transplantation. These ex vivo findings need to be confirmed in a transplant experiment or a clinical trial.

Risk factors and outcomes of massive red blood cell transfusion following living donor liver transplantation

OBJECTIVES

To identify the factors influencing blood loss and secondary blood transfusion and to investigate the outcomes of patients who underwent a massive blood transfusion (MBT) following living donor liver transplantation (LDLT).

METHODS

Patients who underwent primary adult-to-adult right hepatic lobe LDLT were included in the study, and were divided into the MBT group [≥6 red blood cell (RBC) units in 24 h] and the non-massive blood transfusion (NMBT) group (<6 RBC units in 24 h). All potential risk factors, length of intensive care unit (ICU) stay and long-term survival rate of the patients in the two groups were analyzed.

RESULTS

The data of 181 eligible patients were retrospectively analyzed. A decreased long-term survival rate, a higher incidence of postoperative infection and prolonged ICU stay were observed in the MBT group. No significant difference was observed in survival rate between patients having platelet transfusion>2 units and ≤2 units. Hemoglobin<100 g/L, platelet counts<70×10(9)/L, fibrinogen level<1.5 g/L and history of upper abdominal surgery were found to be independent risk factors.

CONCLUSIONS

Blood transfusion during LDLT can be predicted using preoperative variables. Massive RBC transfusion may lead to poor long-term survival, higher postoperative infection rate and prolonged ICU stay. Platelet transfusion may not be a risk factor for long-term survival.

Transfusion has no effect on recurrence in hepatitis C after liver transplantation

BACKGROUND

The literature suggests that blood product transfusions have a negative impact on the survival of liver transplant patients. We investigated the impact of intraoperative blood product usage on the survival of liver transplantation patients being transplanted for hepatitis C-related end-stage liver disease. In addition, we analyzed a potentially more sensitive metric, namely disease recurrence and fibrosis progression, obtained from follow-up liver biopsies.

METHODS

We retrospectively studied 194 consecutive patients with hepatitis C virus (HCV) undergoing liver transplantation. To investigate the effect of red blood cell (RBC) or platelet transfusions on post-transplant HCV recurrence, hepatic biopsy data from 4 months and 1 year after transplantation were studied. In addition, survival data were analyzed.

RESULTS

There was no effect of intraoperative RBC or platelet transfusion on either 1- or 5-year patient survival following liver transplantation. There was no difference in HCV disease recurrence or progression of hepatic fibrosis at 4 months or 1 year attributable either to RBC or to platelet transfusion.

CONCLUSION

This study was not able to confirm an effect on the survival of HCV-infected liver transplant patients related to intraoperative transfusion of RBCs or platelets. In addition, these transfusions had no effect on HCV recurrence or fibrosis progression. This is not to condone a liberal transfusion practice, but rather to reassure that when clinically indicated, transfusion does not have a significant impact on patient survival or disease recurrence in HCV-infected liver transplant patients.

Comparative prospective study of two liver graft preservation solutions: University of Wisconsin and Celsior

University of Wisconsin solution (UWS) is the gold standard for graft preservation. Celsior solution (CS) is a new solution not as yet widely used in liver grafts. The aim of this study was to compare the liver function of transplanted grafts stored in these 2 preservation solutions. The primary endpoints were the rates of primary nonfunction (PNF) and primary dysfunction (PDF). We performed a prospective and pseudorandomized study that included 196 patients (representing 104 and 92 livers preserved in UWS and CS, respectively) at La Fe University Hospital (Valencia, Spain) between March 2003 and May 2005. PNF and PDF rates, liver function laboratory parameters, postoperative bleeding, vascular and biliary complications, and patient and graft survival at 3 years were compared for the 2 groups. The 2 groups were similar in terms of donor variables, recipient variables, and surgical techniques. The PNF rates were 2.2% and 1.9% in the CS and UWS groups, respectively (P = not significant), and the PDF rates were 15.2% and 15.5% in the CS and UWS groups, respectively (P = not significant). There were no significant differences in the laboratory parameters for the 2 groups, except for alanine aminotransferase levels in month 3, which were lower in the CS group (P = 0.01). No significant differences were observed in terms of complications. Three-year patient and graft survival rates were as follows for years 1, 2, and 3: 83%, 80%, and 76% (patient) and 80%, 77%, and 73% (graft) for the UWS group and 83%, 77%, and 70% (patient) and 81%, 73%, and 67% (graft) for the CS group (P = not significant). In conclusion, this study shows that CS is as effective as UWS in liver preservation.

Liver transplantation cost in the model for end-stage liver disease era: looking beyond the transplant admission

We examined the relationship between the total cost incurred by liver transplantation (LT) recipients and their Model for End-Stage Liver Disease (MELD) score at the time of transplant. We used a novel database linking billing claims from a large private payer with the Organ Procurement and Transplantation Network registry. Included were adults who underwent LT from March 2002 through August 2007 (n = 990). Claims within the year preceding and following transplantation were analyzed according to the recipient's calculated MELD score. Cost was the primary endpoint and was assessed by the length of stay and charges. Transplant admission charges represented approximately 50% of the total cost of LT. MELD was a significant cost driver for pretransplant, transplant, and total charges. A MELD score of 28 to 40 was associated with additional charges of $349,213 (P < 0.05) in comparison with a score of 15 to 20. Pretransplant and transplant admission charges were higher by $152,819 (P < 0.05) and $64,286 (P < 0.05), respectively, in this higher MELD group. No differences by MELD score were found for posttransplant charges. Those in the highest MELD group also experienced longer hospital stays both in the pretransplant period and at the time of LT but did not have higher rates of re-admissions. In conclusion, high-MELD patients incur significantly higher costs prior to and at the time of LT. Following LT, the MELD score is not a significant predictor of cost or re-admission.

Incidence of prolonged length of stay after orthotopic liver transplantation and its influence on outcomes

Orthotopic liver transplantation (OLT) is the only effective treatment for end-stage liver disease. Although most patients do well and are discharged promptly, some require prolonged length of stay (PLOS). The prevalence of PLOS, associated factors, and their impact on survival are not well defined. We reviewed our adult OLT database for patients who survived > 30 days. PLOS was defined as hospitalization > 30 days following OLT. Of 521 OLT recipients, 68 (13%) had PLOS with a median duration of 50 days versus only 10 days for patients discharged within 30 days. Significant differences in pre-OLT variables between patients with and without PLOS included the mean wait list time (P = 0.001), hospitalization at the time of OLT (P = 0.001), and prior OLT (P = 0.041). Factors independently associated with PLOS included intensive care unit status at the time of OLT [odds ratio (OR), 4; 95% confidence interval (CI), 1.6-10.4], OLT prior to Model for End-Stage Liver Disease implementation (OR, 2.27; 95% CI, 1.04-5.26), in-hospital post-OLT bacterial infection (OR, 9.34; 95% CI, 4.65-18.86), gastrointestinal bleeding (OR, 4.34; 95% CI, 1.4-14.08), renal failure (OR, 10.86; 95% CI, 5.07-23.25), and allograft rejection (OR, 3.7; 95% CI, 1.23-11.11). One-year graft survival and patient survival were significantly less in those with PLOS (for both, P < 0.0001). Among PLOS patients, factors independently associated with increased 1-year mortality were donor age (OR, 1.07; 95% CI, 1.009-1.13), primary diagnosis of hepatitis C virus (OR, 6.89; 95% CI, 1.40-34.48), in-hospital post-OLT bacterial infection (OR, 13.3; 95% CI, 2.11-83.33), and cardiac complications (OR, 20.4; 95% CI, 1.51-250; c-statistic for the model, 0.85). In conclusion, PLOS following OLT is associated with a significant decrease in survival despite a marked increase in cost and resource utilization. Efforts to modify those factors that contribute to PLOS may reduce this event, improve survival, and reduce OLT-associated costs.

The impact of intraoperative transfusion of platelets and red blood cells on survival after liver transplantation

BACKGROUND

Intraoperative transfusion of red blood cells (RBC) is associated with adverse outcome after orthotopic liver transplantation (OLT). Although experimental studies have shown that platelets contribute to reperfusion injury of the liver, the influence of allogeneic platelet transfusion on outcome has not been studied in detail. In this study, we evaluate the impact of various blood products on outcome after OLT.

METHODS

Twenty-nine variables, including blood product transfusions, were studied in relation to outcome in 433 adult patients undergoing a first OLT between 1989 and 2004. Data were analyzed using uni- and multivariate stepwise Cox's proportional hazards analyses, as well as propensity score-adjusted analyses for platelet transfusion to control for selection bias in the use of blood products.

RESULTS

The proportion of patients receiving transfusion of any blood component decreased from 100% in the period 1989-1996 to 74% in the period 1997-2004. In uni- and multivariate analyses, the indication for transplantation, transfusion of platelets and RBC were highly dominant in predicting 1-yr patient survival. These risk factors were independent from well-accepted indices of disease, such as the Model for End-Stage Liver Disease score and Karnofsky score. The effect on 1-yr survival was dose-related with a hazard ratio of 1.377 per unit of platelets (P = 0.01) and 1.057 per unit of RBC (P = 0.001). The negative impact of platelet transfusion on survival was confirmed by propensity-adjusted analysis.

CONCLUSION

This retrospective study indicates that, in addition to RBC, platelet transfusions are an independent risk factor for survival after OLT. These findings have important implications for transfusion practice in liver transplant recipients.

Platelets in liver transplantation: friend or foe?

Apart from the well-known role of blood platelets in hemostasis, there is emerging evidence that platelets have various nonhemostatic properties that play a critical role in inflammation, angiogenesis, tissue repair and regeneration, and ischemia/reperfusion (I/R) injury. All these processes may be involved in the (patho)physiological alterations occurring in patients undergoing liver transplantation. Experimental and clinical research points toward a dualistic role of platelets in patients undergoing liver transplantation, resulting in both beneficial and detrimental effects. Although a low platelet count is generally considered a risk factor for perioperative bleeding, recent studies have indicated that platelet function in patients with cirrhosis may not be as abnormal as previously assumed. Platelet transfusions are frequently considered in liver transplant recipients to correct low platelet counts and to prevent bleeding; however, evidence-based transfusion thresholds are lacking, and the other detrimental and nonhemostatic properties of platelets are generally not weighed in this respect. First, platelets have been shown to contribute to I/R injury of the liver graft via induction of sinusoidal endothelial cell apoptosis. Second, platelet transfusion has been identified as an independent risk factor for reduced survival via mechanisms that are not completely understood yet. On the other hand, recent studies indicate that platelets are critically involved in restoration after liver injury and in liver regeneration via serotonin-mediated mechanisms. These findings make platelets both friend and foe in liver transplantation. The scientific challenge will be to further dissect the mechanisms and clinical relevance of these contrasting roles of platelets in liver transplantation.

Current concepts in transplant surgery: liver transplantation today

INTRODUCTION

The discipline of liver transplantation (LTx) has been developed over the past decades, and LTx is now considered the gold standard for the treatment of patients with end-stage liver diseases and early liver tumors in cirrhotic livers. This procedure is now performed routinely in many transplant centers, and it has provided an enormous technical innovation to the field of hepatobiliary surgery. Allocation decision of liver organs is based on medical need and timing.

MATERIALS AND METHODS

The Mayo Model for End Stage Liver Disease based on patient-specific criteria was developed and applied to prioritize patients on the waiting list. From the donor aspects of LTx, sources of organ, excluding xenotransplantation, can be brain-dead donors, living donors, and non-heart-beating donors. Today, the majority of livers are procured from cadaveric donors. In addition to the conventional LTx, other types are living-donor LTx, reuse of grafts as domino transplantation, ex situ as well as in situ split LTx, and reduced-size LTx. The transplantation procedure consists of several steps including donor selection and management, liver procurement and preservation, back-table preparation, recipient operation with liver implantation, postoperative care, immunosuppression, and follow-up.

RESULTS

The postoperative complications are divided into surgical, non-surgical, and multifactorial complications. Surgical complications account about 34% of morbidities after LTx and are mainly categorized to vascular and biliary complications. The main medical ones are non-surgical bleeding and infections. The multifactorial complications include primary non- or poor function and small-for-size syndrome. The pretransplant outcome predictors of LTx can be divided into donor, recipient, operative, and postoperative factors.

CONCLUSION

LTx is now considered a safe and standardized procedure with a substantially improved graft and patient survival and acceptable morbidity rates. However, the new problems, including recurrence of hepatitis C or hepatocellular carcinoma, chronic biliary complications, opportunistic infections, and development of de-novo malignancies are the major problems affecting the long-term outcome of transplanted patients.

Predictors of outcomes after pediatric liver transplantation: an analysis of more than 800 cases performed at a single institution

BACKGROUND

Pediatric liver transplantation (PLTx) is the standard of care for treatment of liver failure in children. Unfortunately, there are few studies with substantial numbers of patients that identify outcomes predictors. The goal of this study was to determine factors that influence outcomes in a large, single-center cohort of PLTx.

STUDY DESIGN

This retrospective review between 1984 to 2006 included all recipients 18 years of age and younger undergoing PLTx. Multiorgan graft recipients were excluded (n = 48). Data sources included transplantation center database and hospital medical records. Outcomes measures were overall patient and graft survival. Demographic, laboratory, and perioperative variables were analyzed. Univariate and multivariate statistical analysis was undertaken using log-rank test and Cox's proportional hazards model. A p value < 0.05 was considered significant at the multivariate level.

RESULTS

Eight hundred fifty-two PLTx were performed in 657 children; 55% were girls, 45% were Hispanic, and median age was 29.5 months. Biliary atresia and acute liver failure were the most common causes of liver disease. Fifty-two percent were hospitalized before PLTx. Graft types were whole (75%) and segmental (25%). Indications for re-PLTx (n = 195) included graft nonfunction (22%), immunologic (34%), and vascular complications (35%). Overall 1-, 5-, and 10-year survival rates were 85%, 81%, and 78% (patient), and 78%, 72%, and 67% (graft). Independent significant predictors of worse patient survival were renal function, pretransplantation ventilator dependence, and causes of liver disease. Independent significant predictors of worse graft survival were renal function and warm ischemia time.

CONCLUSIONS

As one of the largest, single-center analyses of PLTx, this study enables accurate statistical analysis and demonstrates excellent longterm outcomes. Independent prognosticators of graft survival were renal function and warm ischemia time, and those for patient survival were renal function, mechanical ventilation, and causes of liver disease. These factors can aid in the medical decision making required for optimal use of scarce donor organs.

Physician predictions of graft survival following liver transplantation

INTRODUCTION

Due to the scarcity of cadaveric livers, clinical judgment must be used to avoid futile transplants. However, the accuracy of human judgment for predicting outcomes following liver transplantation is unknown. The study aim was to assess expert clinicians' ability to predict graft survival and to compare their performance to published survival models.

MATERIALS AND METHODS

Pre-transplant case summaries were prepared based on 16 actual, randomly selected liver transplants. Clinicians specializing in the care of liver transplant patients were invited to assess the likelihood of 90-day graft survival for each case using (1) a 4-point Likert scale ranging from poor to excellent, and (2) a visual analog scale denoting the probability of survival. Four published models were also used to predict survival for the 16 cases. RESULTS. Completed instruments were received from 50 clinicians. Prognostic estimates on the two scales were highly correlated (median r=0.88). Individual clinicians' predictive ability was 0.61+/-0.13, by area under the receiver operating characteristic curve. The performance of published models was MELD 0.59, Desai 0.66, Ghobrial 0.61, and Thuluvath 0.45. For three cases, clinicians consistently overestimated the probability of survival (87+/-10%, 89+/-9%, 86+/-9%); these patients had early graft failures caused by postoperative complications. DISCUSSION. Clinicians varied in their ability to predict survival for a set of pre-transplant scenarios, but performed similarly to published models. When clinicians overestimated the chance of transplant success, either sepsis or hepatic artery thrombosis was involved; such events may be hard to predict before surgery.

Differentially Expressed Genes in Postperfusion Biopsies Predict Early Graft Dysfunction After Liver Transplantation

BACKGROUND

Preservation induced injury is a major contributing factor to early graft dysfunction in liver allograft recipients. We hypothesized that changes in gene expression represent the earliest indicator of ischemia/reperfusion-related injuries measurable in the graft and could be used as prognostic marker for the occurrence of graft-related complications.

METHODS

We studied the expression of 67 genes, known to play a role in acute inflammatory processes by real-time polymerase chain reaction in 59 postperfusion biopsies. The level of expression was correlated with the occurrence of graft-related complications.

RESULTS

We identified six genes that were significantly correlated with the occurrence of early graft dysfunction (Spearman test, two-tailed; P<0.05). High C-reactive protein (CRP) gene expression levels correlated significantly with the need of therapeutic interventions due to graft-related complications (P=0,011). Furthermore, five genes related to vascular endothelial cell physiology (CTGF, WWP2, CD274, VEGF. and its receptor FLT1) showed significantly reduced expression in the postperfusion biopsies of patients with need of therapeutic interventions due to graft-related complications in the first month (P<0.05). Using a risk score based on the expression of these five genes, complications could be predicted with 96% sensitivity (ROC analysis, specificity: 74%, positive predictive value: 72%, negative predictive value: 96%).

CONCLUSION

Quantitative gene expression analysis in postperfusion biopsies may be a valuable tool to prospectively identify patients at risk for early clinical allograft dysfunction after liver transplantation.

Acute blood leukocyte reduction after liver reperfusion: a marker of ischemic injury

INTRODUCTION

Reperfusion injury occurs after ischemic storage of the liver. The release of free radicals from endothelial cells leads to increased adherence of polymorphonuclear neutrophils to endothelium and further release of proteases and free radicals that alter the microcirculation and produce graft dysfunction. Acute blood leukocyte reduction after reperfusion may be an expression of this sequestration and activation of neutrophils within hepatic sinusoids. This study sought to evaluate whether reduction in white blood cells occurring immediately after reperfusion was a marker of poor graft preservation and postoperative dysfunction.

METHODS

The leukocyte count was evaluated at the end of anhepatic phase and at 5 minutes after reperfusion among 65 patients undergoing liver transplantation. Group A included patients with a leukocyte reduction between the two phases greater than 50%; group B, patients with less than 50%. Hepatic enzymes, blood lactate (60 and 120 minutes after graft reperfusion) and factor V and VII and bilirubin levels (daily for 15 days after transplantation) were compared between groups to assess graft injury and postoperative dysfunction.

RESULTS

Alanine aminotransferase levels were significantly higher among group A than group B at both 60 and 120 minutes after graft reperfusion. No differences were observed in lactate, and factor V and VII levels. Total bilirubin was significantly higher among group A than group B patients at 10 and 15 days postoperative.

CONCLUSIONS

The acute blood leukocyte reduction after reperfusion, probably due to sequestration and activation into hepatic sinusoids, seemed to be an early intraoperative marker for poor graft preservation and function.

Causes of early acute graft failure after liver transplantation: analysis of a 17-year single-centre experience

Despite satisfactory overall results reported, early post-operative period after liver transplantation (LT) still represents a critical time with persistently high rate of graft loss. We retrospectively reviewed our experience of 17 yr in LT, analysing the impact on grafts and patient survivals of the acute complications affecting the graft in the early period following LT. To evaluate the changes that occurred over the years in case of early acute graft failure (EAGF), the study population was divided into three equal groups of 223 patients corresponding to three different periods. Ninety (13.5%) experienced an EAGF. Causes of EAGF were hepatic artery thrombosis (HAT) in 32 cases (4.8%), primary graft non-function in 29 cases (4.3%), caval stenosis in 19 (2.8%), early irreversible acute rejection in 6 (0.9%) and portal vein thrombosis in 4 (0.6%). The use of elderly donors and the introduction of the piggyback technique proved to be associated with a higher incidence of HAT and caval stenosis, respectively. Female recipients of male donors were independently associated with Primary graft non-function. Of 90 patients with EAGF, 20 (22.2%) died within the first month after LT, 34 (37.8%) underwent retransplantation (ReLT) and 36 (40%) received conservative treatment. Conservative treatments increased from 3.6% in the first group to 47.0 and 66.8% in the second and third one (p = 0.000). One-year graft and patient survival of patients with EAGF significantly improved over the three eras analysed. The incidence of EAGF remains consistent. Nevertheless, a better understanding of the clinical situations and changes in treatment strategies have led to significant improvements in terms of graft and patient survival rates, now close to the survival rate of EAGF-free patients.

Initial hepatic microcirculation correlates with early graft function in human orthotopic liver transplantation

Microcirculatory disturbances are an initial causative determinant in hepatic ischemia/reperfusion injury. The aim of this study was to assess sinusoidal perfusion during human liver transplantation using orthogonal polarization spectral imaging and to evaluate the significance of intraoperative microcirculation for early postoperative graft function. Hepatic microcirculation was measured in 27 recipients undergoing full-size liver transplantation and compared to a group of 32 healthy living-related liver donors. The microvascular parameters were correlated with postoperative aspartate aminotransferase and bilirubin levels. Hepatic perfusion following liver transplantation was found to be significantly decreased when compared with the control group. Volumetric blood flow within the individual sinusoids increased due to sinusoidal dilatation and enhanced flow velocity. Regression analysis of postoperative aspartate aminotransferase and bilirubin with microvascular parameters revealed significant correlations. The extent of volumetric blood flow increased within the first 30 minutes after reperfusion and showed a significant correlation with postoperative aspartate aminotransferase release and bilirubin elimination. In conclusion, postischemic hepatic microvascular perfusion was analyzed in vivo, demonstrating significant microvascular impairment during liver transplantation. Sinusoidal hyperperfusion appears to confer protection against postischemic liver injury, as given by the correlation with aspartate aminotransferase and bilirubin levels. Thus, these findings may have therapeutic importance with respect to mechanisms mediating postischemic reactive hyperemia.

Surgical advances in liver and bowel transplantation

Liver and intestinal transplantation are currently the treatments of choice for life-threatening hepatic and gastrointestinal failure. These technologies have evolved through contributions from the fields of immunology, anatomy, physiology, surgery, anesthesiology, critical care, ethics, epidemiology, and public health. Transplantation now accounts for the treatment of over 5,000 recipients per year who are in a state of organ failure. The available donor population, however, is not increasing to meet the demands of the faster growing recipient population. This discrepancy has led to the rapid development of novel strategies that require critical evaluation to build on the success rates in recent years. This article presents the most salient advances in liver and intestinal transplantation in the last 15 years.

Living-related liver transplantation: implication for the anaesthetist

PURPOSE OF REVIEW

Living donor liver transplantation, originally introduced about a decade ago to overcome paediatric cadaveric organ shortage, has rapidly gained acceptance within the transplant community and is nowadays almost routinely applied to the growing number of adult and paediatric patients awaiting a live-saving liver transplantation. In fact its introduction has contributed to a continuing decrease of waiting list deaths.

RECENT FINDINGS

The risk of potential complications and even death for the donor increases with the extent of liver tissue resected. Better preoperative evaluation of suitability, refinement of surgical technique and smarter anaesthetic management, based on extended knowledge of underlying pathophysiology, have made the procedure safer for donors, with low morbidity and even lower mortality rates, tending towards zero in experienced centres. Despite these improvements, a certain risk is inherent. Yet from an ethical point of view it has to remain unacceptable especially because donors are otherwise healthy people and their only motives are altruistic. The procedure of living donor liver transplantation like conventional liver transplantation involves various disciplines, each of which contributes in a specific manner. There is a broad scope of issues that anaesthetists are responsible for and these largely depend on the department and hospital requirements. These issues may range from perioperative anaesthetic management and pain relief, to--and there are definite continental differences--the coordination of donor evaluation, intensive care management, postoperative complication management, as well as psychological support for donors, recipients and their relatives.

SUMMARY

In this paper we review and summarize the potential impact of findings and advances made in this particular field as described by the most important articles published during the past year.