Does modification of portal pressure and flow enhance recovery of the recipient after living donor liver transplantation? A systematic review of literature and expert panel recommendations

Small for Size Syndrome in Living Donor Liver Transplantation- Prevention and Management

Small-for-size syndrome is a clinical syndrome of early allograft dysfunction usually following living donor liver transplantation due to a mismatch between recipient metabolic and functional requirements and the graft's functional capacity. While graft size relative to the recipient size is the most commonly used parameter to predict risk, small-for-size syndrome is multifactorial and its development depends on a number of inter-dependant factors only some of which are modifiable. Intra-operative monitoring of portal haemodynamics and portal flow modulation is widely recommended though there is wide variation in clinical practice. Management of established small-for-size syndrome centres around meticulous patient care, infection prevention, fluid management and identifying correctable technical complications. However, retransplantation is the only treatment in severe cases. While small-for-size syndrome per se is associated with increased peri-operative mortality, the contribution of non-hepatic organ failure in determining patient outcomes needs further studies.

Special Techniques of Liver Transplantation: Living Donor Liver Transplantation With Right Posterior Sector Grafts and Extended Left Lobe Grafts; Auxiliary Partial Orthotopic Liver Transplantation, and Dual-Lobe Liver Transplantation

Living donor liver transplantation (LDLT) constitutes the majority of liver transplants in Asia and advancements in LDLT techniques have expanded the range of allografts beyond the commonly used right lobe (RL). This review provides a comprehensive overview of lesser-known variants of allografts and LDLT techniques which include right posterior sector grafts (RPSG), dual-lobe liver transplantation (DLLT), auxiliary partial orthotopic liver transplantation (APOLT), and extended left lobe grafts with caudate concentrating on the technical aspects, current evidence, and their indications in contemporary practice of LDLT. The first section examines RPSGs, focussing on their potential as an alternative to RL grafts particularly when volumetric studies indicate a larger right posterior sector in donors. It addresses donor selection, surgical techniques, and potential complications. Next, the article explores DLLT, which optimizes graft volume through partial grafts from two donors. The emphasis is on the ethical considerations, surgical challenges, and haemodynamic risks, such as graft atrophy, highlighting the importance of careful donor selection and meticulous planning. The section on APOLT covers its application in treating acute liver failure (ALF) and metabolic liver diseases. The technique's ability to support liver function in ALF while avoiding long-term immunosuppression when the native liver regenerates is discussed, along with patient selection criteria and follow-up requirements. Finally, the review addresses left lobe grafts with caudate used in smaller adults and older children to increase functional graft volume and improve outcomes.

Intraoperative Hemodynamic Monitoring and Prediction of Early Allograft Dysfunction Following Living Donor Liver Transplantation: A Systematic Review

BACKGROUND

Multiple intraoperative hemodynamic parameters are associated with an increased risk of early allograft dysfunction (EAD) following living donor liver transplantation (LDLT); however, there is significant center-to-center variability in terms of which parameters are used. We sought to determine which intraoperative hemodynamic parameters are most predictive of EAD following LDLT.

METHODS

This is a systematic review following PRISMA guidelines (PROSPERO ID: CRD42023409711). Receiver operating characteristic (ROC) analyses were used to compare predictive parameters.

RESULTS

A total of 4399 articles were identified from 3 large, international databases (PubMed, Embase, and Web of Science). Eighteen articles fit the inclusion criteria. The most commonly evaluated hemodynamic parameter was the postreperfusion portal venous pressure (PVP). A postreperfusion PVP of <15-20 mmHg was consistently associated with lower rates of EAD and, in some cases, improvements in patient survival. Other hemodynamic parameters evaluated included portal venous flow, hepatic arterial flow, portal venous velocities, and the hyperperfusion index.

CONCLUSION

Hemodynamic measurements indicative of portal hyperperfusion, especially elevated PVP, have been consistently associated with the development of EAD. Intraoperative hemodynamics should be monitored on all LDLT recipients, with portal inflow modulation procedures indicated if portal hyperperfusion is present.

Prediction and management of small-for-size syndrome in living donor liver transplantation

Small-for-size syndrome (SFSS) remains a critical challenge in living donor liver transplantation (LDLT), characterized by graft insufficiency due to inadequate liver volume, leading to significant postoperative morbidity and mortality. As the global adoption of LDLT increases, the ability to predict and manage SFSS has become paramount in optimizing recipient outcomes. This review provides a comprehensive examination of the pathophysiology, risk factors, and strategies for managing SFSS across the pre-, intra-, and postoperative phases. The pathophysiology of SFSS has evolved from being solely volume-based to incorporating portal hemodynamics, now recognized as small-for-flow syndrome. Key risk factors include donor-related parameters like age and graft volume, recipient-related factors such as MELD score and portal hypertension, and intraoperative factors related to venous outflow and portal inflow modulation. Current strategies to mitigate SFSS include careful graft selection based on graft-to-recipient weight ratio and liver volumetry, surgical techniques to optimize portal hemodynamics, and novel interventions such as splenic artery ligation and hemiportocaval shunts. Pharmacological agents like somatostatin and terlipressin have also shown promise in modulating portal pressure. Advances in 3D imaging and artificial intelligence-based volumetry further aid in preoperative planning. This review emphasizes the importance of a multifaceted approach to prevent and manage SFSS, advocating for standardized definitions and grading systems. Through an integrated approach to surgical techniques, hemodynamic monitoring, and perioperative management, significant strides can be made in improving the outcomes of LDLT recipients. Further research is necessary to refine these strategies and expand the application of LDLT, especially in challenging cases involving small-for-size grafts.

International multicenter study of ultralow graft-to-recipient weight ratio grafts in adult living donor liver transplantation

Decreasing the graft size in living donor liver transplantation (LDLT) increases the risk of early allograft dysfunction. Graft-to-recipient weight ratio (GRWR) of 0.8 is considered the threshold. There is evidence that smaller volume grafts may also provide equally good outcomes, the cut-off of which remains unknown. In this retrospective multicenter study, 92 adult LDLTs with a final GRWR ≤0.6 performed at 12 international liver transplant centers over a 3-year period were included. Perioperative data including preoperative status, portal flow hemodynamics (PFH) and portal flow modulation, development of small for size syndrome (SFSS), morbidity, and mortality was collated and analyzed. Thirty-two (36.7%) patients developed SFSS and this was associated with increased 30-day, 90-day, and 1-year mortality. The preoperative model for end-stage liver disease and inpatient status were independent predictors for SFSS (P < .05). Pre-liver transplant renal dysfunction was an independent predictor of survival (hazard ratio 3.1; 95% confidence intervals 1.1, 8.9, P = .035). PFH or portal flow modulation were not predictive of SFSS or survival. We report the largest ever multicenter study of LDLT outcomes using ultralow GRWR grafts and for the first time validate the International Liver Transplantation Society-International Living donor liver transplantation study group-Liver Transplantation Society of India consensus definition and grading of SFSS. Preoperative recipient condition rather than GRWR and PFH were independent predictors of SFSS. Algorithms to predict SFSS and LT outcomes should incorporate recipient factors along with GRWR.

Splenic Artery Ligation Versus Splenectomy for Portal Inflow Modulation in Adult Living Donor Liver Transplant: Effects on Early Graft Function, A Prospective Study

OBJECTIVES

Portal inflow modulation is currently an essential step in living donor liver transplantation, particularly among patients with portal hypertension who receive small grafts. This study compared splenic artery ligation with splenectomy as a method for portal inflow modulation.

MATERIALS AND METHODS

We compared 31 consecutive prospective adult patients who had splenic artery ligation during living donorlivertransplant with either right or left lobe donation performed from July 2021 to March 2024 with 22 consecutive retrospective patients who had splenectomy performed immediately before July 2021.

RESULTS

No differences were shown between splenic artery ligation and splenectomy groups in demographic data, indication, and Model for End-Stage Liver Disease score. Patients in the splenic artery ligation group had significantly smaller grafts than patients in the splenectomy group (graft-to-recipient weight ratio of 0.89 ± 0.23 vs 1.19 ± 0.24; P<.001) and less right lobes (41.9% [n=13] vs 90.9% [n=20]; P<.001).No significant differences between groups were shown for cold and warm ischemic times and estimated blood loss. Operative time was significantly shorter for patients in the splenic artery ligation versus splenectomy group (8.85 ± 1.33 vs 10.49 ± 0.75 h; P < .001). In the splenic artery ligation group, median portal vein pressure decreased from 19 (range, 16-23) to 14 (range, 11-20) mm Hg. In the splenectomy group, portal vein pressure decreased from 20.5 (range, 17-24) to 14.5 (range, 12-17) mm Hg. Both techniques showed no differences regarding effect on portal inflow modulation (P = .21). Incidence of small-for-size syndrome was not significantly different between groups.

CONCLUSION

Splenic artery ligation was not inferior to splenectomy as a method to perform portal inflow modulation to alleviate graft dysfunction in living donor liver transplant with portal hypertension.

Asian Pacific Association for the Study of the Liver clinical practice guidelines on liver transplantation

Liver transplantation is a highly complex and challenging field of clinical practice. Although it was originally developed in western countries, it has been further advanced in Asian countries through the use of living donor liver transplantation. This method of transplantation is the only available option in many countries in the Asia-Pacific region due to the lack of deceased organ donation. As a result of this clinical situation, there is a growing need for guidelines that are specific to the Asia-Pacific region. These guidelines provide comprehensive recommendations for evidence-based management throughout the entire process of liver transplantation, covering both deceased and living donor liver transplantation. In addition, the development of these guidelines has been a collaborative effort between medical professionals from various countries in the region. This has allowed for the inclusion of diverse perspectives and experiences, leading to a more comprehensive and effective set of guidelines.

An Analysis of 10,000 Cases of Living Donor Liver Transplantation in Japan: Special Reference to the Graft-Versus-Recipient Weight Ratio and Donor Age

OBJECTIVE

To analyze 10,000 cases of living donor liver transplantation (LDLT) recipient data to elucidate outcomes with special reference to the graft-versus-recipient weight ratio (GRWR), based on the Japanese Liver Transplantation Society (JLTS) registry.

BACKGROUND

The JLTS registry has been accurate and complete in characterizing and following trends in patient characteristics and survival of all patients with LDLT.

METHODS

Between November 1989 and August 2021, 10,000 patients underwent LDLT in Japan. The procedures performed during the study period included pediatric liver transplantation (age <18 years, n = 3572) and adult liver transplantation (age ≥18 years, n=6428). Factors related to patient survival (PS) and graft survival (GS) were also analyzed.

RESULTS

The GRWR was <0.7, 0.7 to <0.8, 0.8 to <3, 3 to <5, and ≥5 in 0.2%, 2.0%, 61.8%, 31.8%, and 2.6% of pediatric patients and <0.6, 0.6 to <0.7, 0.7 to <0.8, and ≥0.8 in 8.0%, 12.7%, 17.7%, and 61.5% of adult patients, respectively. Among pediatric recipients, the PS rate up to 5 years was significantly better in cases with a GRWR ≤5 than in those with a GRWR >5. When the GRWR and donor age were combined, among adult recipients 50 to 60 years old, the early PS and GS up to 5 years were significantly better in cases with a GRWR ≥0.7, than in those with a GRWR <0.7. (P = 0.02). In adults, a multivariate analysis showed that GRWR <0.6, transplant era (<2011), donor age (>60 years), recipient age (>60 years), model for end-stage liver disease score (≥20), and center volume (<10) were significant prognostic factors for long-term PS.

CONCLUSION

Although a satisfactory long-term PS and GS, especially in the recent era (2011-2021), was achieved in the JLTS series, a GRWR ≥5 in pediatric cases and relatively old donors with a GRWR <0.7 in adult cases should be managed with caution.

e-GLR Score Predicts Early Graft Loss in Adult Live-Donor Liver Transplantation

Objective

This study aimed to analyze risk factors and develop a predictive model for early allograft loss due to early graft dysfunction (EGD) in adult live-donor liver transplantation (LDLT).

Methods

Data of patients who underwent LDLT from 2011 to 2019 were reviewed for EGD, associated factors, and outcomes. A homogeneous group of 387 patients was analyzed: random cohort A (n = 274) for primary analysis and random cohort B (n = 113) for validation.

Results

Of 274 recipients, 92 (33.6%) developed EGD. The risk of graft loss within 90 days was 29.3% and 7.1% in those with and without EGD, respectively (P < 0.001). Multivariate logistic regression analysis determined donor age (P = 0.045), estimated (e) graft weight (P = 0.001), and the model for end-stage liver disease (MELD) score (0.001) as independent predictors of early graft loss due to EGD. Regression coefficients of these factors were employed to formulate the risk model: Predicted (P) early graft loss risk (e-GLR) score = 10 × [(donor age × 0.052) + (e-Graft weight × 1.681) + (MELD × 0.145)] - 8.606 (e-Graft weight = 0, if e-Graft weight ≥640 g and e-Graft weight = 1, and if e-Graft weight < 640 g). Internal cross-validation revealed a high predictive value (C-statistic = 0.858).

Conclusions

Our novel risk score can efficiently predict early allograft loss following graft dysfunction, which enables donor-recipient matching, evaluation, and prognostication simply and reliably in adult LDLT.

Post Living Donor Liver Transplantation Small-for-size Syndrome: Definitions, Timelines, Biochemical, and Clinical Factors for Diagnosis: Guidelines From the ILTS-iLDLT-LTSI Consensus Conference

BACKGROUND

When a partial liver graft is unable to meet the demands of the recipient, a clinical phenomenon, small-for-size syndrome (SFSS), may ensue. Clear definition, diagnosis, and management are needed to optimize transplant outcomes.

METHODS

A Consensus Scientific committee (106 members from 21 countries) performed an extensive literature review on specific aspects of SFSS, recommendations underwent blinded review by an independent panel, and discussion/voting on the recommendations occurred at the Consensus Conference.

RESULTS

The ideal graft-to-recipient weight ratio of ≥0.8% (or graft volume standard liver volume ratio of ≥40%) is recommended. It is also recommended to measure portal pressure or portal blood flow during living donor liver transplantation and maintain a postreperfusion portal pressure of <15 mm Hg and/or portal blood flow of <250 mL/min/100 g graft weight to optimize outcomes. The typical time point to diagnose SFSS is the postoperative day 7 to facilitate treatment and intervention. An objective 3-grade stratification of severity for protocolized management of SFSS is proposed.

CONCLUSIONS

The proposed grading system based on clinical and biochemical factors will help clinicians in the early identification of patients at risk of developing SFSS and institute timely therapeutic measures. The validity of this newly created grading system should be evaluated in future prospective studies.

Preventing Small-for-size Syndrome in Living Donor Liver Transplantation: Guidelines From the ILTS-iLDLT-LTSI Consensus Conference

Small-for-size syndrome (SFSS) is a well-recognized complication following liver transplantation (LT), with up to 20% developing this following living donor LT (LDLT). Preventing SFSS involves consideration of factors before the surgical procedure, including donor and recipient selection, and factors during the surgical procedure, including adequate outflow reconstruction, graft portal inflow modulation, and management of portosystemic shunts. International Liver Transplantation Society, International Living Donor Liver Transplantation Group, and Liver Transplant Society of India Consensus Conference was convened in January 2023 to develop recommendations for the prediction and management of SFSS in LDLT. The format of the conference was based on the Grading of Recommendations, Assessment, Development, and Evaluation system. International experts in this field were allocated to 4 working groups (diagnosis, prevention, anesthesia, and critical care considerations, and management of established SFSS). The working groups prepared evidence-based recommendations to answer-specific questions considering the currently available literature. The working group members, independent panel, and conference attendees served as jury to edit and confirm the final recommendations presented at the end of the conference by each working group separately. This report presents the final statements and evidence-based recommendations provided by working group 2 that can be implemented to prevent SFSS in LDLT patients.

Early allograft dysfunction after living donor liver transplantation-current concepts and future directions

Early allograft dysfunction (EAD) after liver transplantation is a significant clinical problem that negatively impacts graft and patient outcomes. The rising incidence of EAD and what it means concerning living donor liver transplantation (LDLT) is an area of great interest. However, EAD after LDLT is a complex research topic yet to be reviewed comprehensively. Most of the literature on EAD is based on experience in deceased donor liver transplantation, and limited information is available in the context of LDLT. Thus, in this review, we present an overview of EAD after LDLT and have attempted to present balanced points of view on all its aspects, such as definitions, pathogenesis, risk factors, predictive markers, and management. The review aims to broadly overview the nature and extent of ongoing research evidence on this complex topic and inform practice in the field by identifying key concepts and knowledge gaps and highlighting areas that require further inquiry.

Enhanced recovery for liver transplantation: recommendations from the 2022 International Liver Transplantation Society consensus conference

There is much controversy regarding enhanced recovery for recipients of liver transplants from deceased and living donors. The objectives of this Review were to summarise current knowledge on individual enhanced recovery elements on short-term outcomes, identify key components for comprehensive pathways, and create internationally accepted guidelines on enhanced recovery for liver-transplant recipients. The ERAS4OLT.org collaborative partnered by the International Liver Transplantation Society performed systematic literature reviews on the effect of 32 relevant enhanced perioperative recovery elements on short-term outcomes, and global specialists prepared expert statements on deceased and living donor liver transplantation. The Grading Recommendations, Assessment, Development and Evaluations approach was used for rating of quality of evidence and grading of recommendations. A virtual international consensus conference was held in January, 2022, in which results were presented, voted on by the audience, and discussed by an independent international jury of eight members, applying the Danish model of consensus. 273 liver transplantation specialists from 30 countries prepared expert statements on elements of enhanced recovery for liver transplantation based on the systematic literature reviews. The consensus conference yielded 80 final recommendations, covering aspects of enhanced recovery for preoperative assessment and optimisation, intraoperative surgical and anaesthetic conduct, and postoperative management for the recipients of liver transplants from both deceased and living donors, and for the living donor. The recommendations represent a comprehensive overview of the relevant elements and areas of enhanced recovery for liver transplantation. These internationally established guidelines could direct the development of enhanced recovery programmes worldwide, allowing adjustments according to local resources and practices.

Small-For-Size Syndrome and Graft Inflow Modulation Techniques in Liver Transplantation

BACKGROUND

Partial liver transplantation has recently been proposed to alleviate organ shortages. However, transplantation of a small-for-size graft is associated with an increased risk of posttransplant hepatic dysfunction, commonly referred to as small-for-size syndrome (SFSS). This review describes the etiology, pathological features, clinical manifestations, and diagnostic criteria of SFSS. Moreover, we summarize strategies to improve graft function, focusing on graft inflow modulation techniques. Finally, unmet needs and future perspectives are discussed.

SUMMARY

In fact, posttransplant SFSS can be attributed to various factors such as preoperative status of the recipients, surgical techniques, donor age, and graft quality, except for graft size. With targeted improvement measures, satisfactory clinical outcomes can be achieved in recipients at increased risk of SFSS. Given the critical role of relative portal hyperperfusion in the pathogenesis of SFSS, various pharmacological and surgical treatments have been established to reduce or partially divert excessive portal inflow, and recipients will benefit from individualized therapeutic regimens after careful evaluation of benefits against potential risks. However, there remain unmet needs for further research into different aspects of SFSS to better understand the correlation between portal hemodynamics and patient outcomes.

KEY MESSAGES

Contemporary transplant surgeons should consider various donor and recipient factors and develop case-specific prevention and treatment strategies to improve graft and recipient survival rates.