Graft weight/recipient weight ratio: how well does it predict outcome after partial liver transplants?

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.

Management of Established Small-for-size Syndrome in Post Living Donor Liver Transplantation: Medical, Radiological, and Surgical Interventions: Guidelines From the ILTS-iLDLT-LTSI Consensus Conference

Small-for-size syndrome (SFSS) following living donor liver transplantation is a complication that can lead to devastating outcomes such as prolonged poor graft function and possibly graft loss. Because of the concern about the syndrome, some transplants of mismatched grafts may not be performed. Portal hyperperfusion of a small graft and hyperdynamic splanchnic circulation are recognized as main pathogenic factors for the syndrome. Management of established SFSS is guided by the severity of the presentation with the initial focus on pharmacological therapy to modulate portal flow and provide supportive care to the patient with the goal of facilitating graft regeneration and recovery. When medical management fails or condition progresses with impending dysfunction or even liver failure, interventional radiology (IR) and/or surgical interventions to reduce portal overperfusion should be considered. Although most patients have good outcomes with medical, IR, and/or surgical management that allow graft regeneration, the risk of graft loss increases dramatically in the setting of bilirubin >10 mg/dL and INR>1.6 on postoperative day 7 or isolated bilirubin >20 mg/dL on postoperative day 14. Retransplantation should be considered based on the overall clinical situation and the above postoperative laboratory parameters. The following recommendations focus on medical and IR/surgical management of SFSS as well as considerations and timing of retransplantation when other therapies fail.

Technical challenges in LDLT - Overcoming small for size syndrome and venous outflow reconstruction

Living Donor Liver Transplantation (LDLT) emerged as an alternative treatment option for patients with end-stage liver disease waiting for an organ from a deceased donor. In addition to allowing for a faster access to transplantation, LDLT provides improved recipient outcomes when compared to deceased donor LT. However, it represents a more complex and demanding procedure for the transplant surgeon. In addition to a comprehensive preoperative donor assessment and stringent technical considerations during the donor hepatectomy to ensure upmost donor safety, the recipient procedure also comes with intrinsic challenges during LDLT. A proper approach during both procedures will result in favorable donor and recipient's outcomes. Hence, it is critical for the transplant surgeon to know how to overcome such technical challenges and avoid deleterious complications. One of the most feared complications following LDLT is small-for-size syndrome (SFSS). Although, surgical advances and deeper understanding of the pathophysiology behind SFSS has allowed for a safer implementation of LDLT, there is currently no consensus on the best strategy to prevent or manage this complication. Therefore, we aim to review current practices in technically challenging situations during LDLT, with a particular focus on management of small grafts and venous outflow reconstructions, as they possess one of the biggest technical challenges faced during LDLT.

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.

Successful living donor liver transplantation with a graft-to-recipient weight ratio of 0.41 without portal flow modulation: A case report

BACKGROUND

There have been numerous efforts to lower the limit of minimum graft size to meet the metabolic demand of recipients in adult-to-adult living donor liver transplantation (LDLT). We experienced a successful case of LDLT using a very-small-for-size graft without portal flow modulation such as splenectomy or portocaval shunt.

CASE SUMMARY

A 49-year-old man (weighing 91 kg) suffering hepatocellular carcinoma accompanied with hepatitis B virus related cirrhosis underwent LDLT. The one and only voluntary donor was his 17-year-old daughter whose body weight was 50 kg with a body mass index (BMI) of 18.3. The procured right liver graft was 411 g with a real graft-to-recipient weight ratio (GRWR) of 0.41%, the smallest to be reported in the literature. Both the recipient and donor had an uneventful recovery and were discharged on days 15 and 8, respectively, with normal liver function. The father and daughter have had no complication so far and are still in good health with normal liver function 81 mo after LDLT.

CONCLUSION

Satisfactory outcomes can be achieved in LDLT with a GRWR as low as 0.41% even without using portal flow modulation in highly selected patients.

Correlation between liver volume and liver weight in a cohort with chronic liver disease: a semiautomated CT-volumetry study

BACKGROUND

To estimate the optimal density coefficient for conversion of liver volume into liver weight in patients with chronic liver disease based on semiautomated CT-liver volumetry data and the histologic Ishak score of explanted liver.

METHODS

A total of 114 patients (39 female; age, 46±20 years) with chronic liver diseases who underwent liver transplantation between January 2010 and September 2020 were identified over a patient chart search at our institution and subsequently analyzed in retrospect. All patients had contrast-enhanced CT-examinations (mean, 24 days) to liver transplantation. Liver volume was calculated by a semiautomated software and results compared with the liver weight registered by the pathologist. Each explanted liver was histologically scored into six classes according to the Ishak classification where the categories were subgrouped based on recommendation of the pathologists into the following categories 0-3, 4-5 and 6.

RESULTS

Mean liver volume was 1,870±1,195, 1,162±679 and 1,278±510 mL for the categories 0-3, 4-5 and 6, respectively. Mean liver weight was 1,624±999, 1,082±669 and 1,346±559 g for the categories 0-3, 4-5 and 6, respectively. A coefficient of 0.92±0.22, 0.98±0.28 and 1.06±0.20 g/mL was found at best for conversion of liver volume into liver weight in these subgroups. Differences between Ishak-subgroups proved significant (0.002). In 4 patients with cystic liver disease, density coefficients varied significantly and were found generally lower compared to the other liver disorders.

CONCLUSIONS

Our results yielded significant differences between the density coefficients calculated along with the Ishak score and also for the subgroup with cystic liver disease.

Current status of left lobe adult to adult living donor liver transplantation

PURPOSE OF REVIEW

This review describes the history and current state of left lobe living donor liver transplantation (LDLT). The transplant community continues to face an organ shortage on a global scale, and the expansion of LDLT is attractive because it allows us to provide life-saving liver transplants to individuals without drawing from, or depending on, the limited deceased donor pool. Donor safety is paramount in LDLT, and for this reason, left lobe LDLT is particularly attractive because the donor is left with a larger remnant.

RECENT FINDINGS

This article reviews the donor and recipient evaluations for left lobe LDLT, discusses small for size syndrome and the importance of portal inflow modification, and reviews recipient outcomes in right lobe versus left lobe LDLT.

SUMMARY

Left lobe LDLT was the first adult-to-adult LDLT ever to be performed in Japan in 1993. Since that time, the use of both right and left lobe LDLT has expanded immensely. Recent work in left lobe LDLT has emphasized the need for inflow modification to reduce portal hyperperfusion and early graft dysfunction following transplant. Accumulating evidence suggests, however, that even though early graft dysfunction following LDLT may prolong hospitalization, it does not predict graft or patient survival.

Donor-Recipient Height Mismatch Is Associated With Decreased Survival in Pediatric-to-Adult Liver Transplant Recipients

Liver grafts from pediatric donors represent a small fraction of grafts transplanted into adult recipients, and their use in adults requires special consideration of donor size to prevent perioperative complications. In the past, graft weight or volume ratios have been adopted from the living donor liver transplant literature to guide clinicians; however, these metrics are not regularly available to surgeons accepting deceased donor organs. In this study, we evaluated all pediatric-to-adult liver transplants in the United Network for Organ Sharing Standard Transplant Analysis and Research database from 1987 to 2019, stratified by donor age and donor-recipient height mismatch ratio (HMR; defined as donor height/recipient height). On multivariable regression controlling for cold ischemia time, age, and transplantation era, the use of donors from ages 0 to 4 and 5 to 9 had increased risk of graft failure (hazard ratio [HR], 1.81 [P < 0.01] and HR, 1.16 [P < 0.01], respectively) compared with donors aged 15 to 17. On Kaplan-Meier survival analysis, a HMR < 0.8 was associated with inferior graft survival (mean, 11.8 versus 14.6 years; log-rank P < 0.001) and inferior patient survival (mean, 13.5 versus 14.9 years; log-rank P < 0.01) when compared with pairs with similar height (HMR, 0.95-1.05; ie, donors within 5% of recipient height). This study demonstrates that both young donor age and low HMR confer additional risk in adult recipients of pediatric liver grafts.

Adult liver transplantation using pediatric donor livers after cardiac or brain death: A report of three cases

The present study reports on the experience at Jiangxi Provincial People's Hospital (Nanchang, China) with liver transplantation in adults using pediatric donor livers, including indications, technique and results. A total of three cases of liver transplantation performed between April 2008 and May 2016 were retrospectively reviewed. Liver procurement and trimming, recipient selection, surgical tips, prevention and treatment of small-for-size syndrome, selection of immunosuppressive regimens, prevention and treatment of vascular complications and anticoagulant therapy were discussed. The three pediatric donors were 8, 8 and 10 years old. The three recipients were confirmed to have primary liver cancer. In recipient 1 (female; age, 39 years), jaundice persisted in the recipient after the liver transplantation. A reduced dose of FK506 was then given to gradually decrease the total bilirubin level to the normal range. Recipient 1 recovered and was discharged from hospital; however, the patient died of liver cancer recurrence and bone metastasis 6 years post-transplantation. In recipient 2 (male; age, 56 years), the recipient experienced sudden abdominal distension on postoperative day 7. The patient's clotting time was prolonged and the transaminase level was sharply increased, peaking on day 9. The patient was suspected of having small-for-size syndrome and was treated symptomatically. The patient experienced a significant improvement in symptoms on postoperative day 13 and regular postoperative follow-ups were performed until now and the patient is now in remission. In recipient 3 (male; age, 48 years), the recipient recovered well and the liver function returned to normal on postoperative day 3. The patient was discharged from hospital and has been in remission thus far. Adult liver transplantations from pediatric donors are feasible treatments. Systematic donor and recipient assessments, sound surgical skills and optimal postoperative treatments are essential for success in the transplantation of livers from pediatric donors into adult recipients. Considering the condition of the donor liver, the selection of recipients and appropriate surgical methods are particularly important in these cases.

Pulse oximetry-based capillary refilling evaluation predicts postoperative outcomes in liver transplantation: a prospective observational cohort study

Background

Capillary refill time (CRT) is a non-invasive technique to evaluate tissue perfusion, and quantitative CRT (Q-CRT) adapted to pulse oximetry was developed with patients with sepsis and compared to blood lactate and sepsis scores. In post liver transplantation, large amounts of fluid administration are necessary for maintaining tissue perfusion to grafted liver against intravascular hypovolemia. This study aimed to evaluate whether Q-CRT can predict poor outcomes by detecting peripheral tissue perfusion abnormality in patients with liver transplantations who were treated with massive fluid administration.

Methods

In this single-center prospective cohort study, we enrolled adult patients with liver transplantations between June 2018 and July 2019. Measurement of Q-CRT was conducted at intensive care units (ICU) admission and postoperative day 1 (POD1).

Results

A total of 33 patients with liver transplantations were enrolled. Significant correlations of Q-CRT and ΔA_b, a tissue oxygen delivery parameter calculated by pulse oximetry data, at ICU admission with the postoperative outcomes such as length of ICU and hospital stay and total amount of ascitic fluid discharge were observed. Quantitative CRT and ΔA_b at ICU admission were significantly associated with these postoperative outcomes, even after adjusting preoperative and operative factors (MELD score and bleeding volume, respectively). However, quantitative CRT and ΔA_b at POD1 and changes from ICU admission to POD1 failed to show significant associations.

Conclusions

Q-CRT values were significantly associated with postoperative outcomes in liver transplantation. Although the mechanisms of this association need to be clarified further, Q-CRT may enable identification of high-risk patients that need intensive postoperative managements.

Small-for-size graft, small-for-size syndrome and inflow modulation in living donor liver transplantation

The extended application of living donor liver transplantation (LDLT) has revealed the problem of graft size mismatching called "small-for-size syndrome (SFSS)." The initial trials to resolve this problem involved increasing the procured graft size, from left to right, and even extending to include a right lobe graft. Clinical cases of living right lobe donations have been reported since then, drawing attention to the risks of increasing the liver volume procured from a living donor. However, not only other modes of increasing graft volume (GV) such as auxiliary or dual liver transplantation, but also control of the increased portal pressure caused by a small-for-size graft (SFSG), such as a porto-systemic shunt or splenectomy and optimal outflow reconstruction, have been trialed with some positive results. To establish an effective strategy for transplanting SFSG and preventing SFSS, it is essential to have precise knowledge and tactics to evaluate graft quality and GV, when performing these LDLTs with portal pressure control and good venous outflow. Thus, we reviewed the updated literature on the pathogenesis of and strategies for using SFSG.

Association of Graft-to-Recipient Weight Ratio with the Prognosis Following Liver Transplantation: a Meta-analysis

BACKGROUND

Studies indicate that low graft-to-recipient weight ratio (GRWR) affect graft survival in adult-to-adult living donor liver transplantation. However, the potential role of GRWR in the prognosis of patients following living donor liver transplantation according to patient characteristics remains controversial. This study aimed to update the role of GRWR in patients following living donor liver transplantation.

METHODS

PubMed, Embase, and Cochrane Library were comprehensively searched for studies comparing low GRWR (< 0.8%) with normal GRWR (≥ 0.8%) in the prognosis following living donor liver transplantation from inception to March 2019. The 1-, 3-, and 5-year summary survival rates, small-for-size syndrome (SFSS), perioperative mortality, biliary complications, postoperative bleeding, and acute rejection were calculated using the random-effects model.

RESULTS

Eighteen studies comprising 4001 patients were included. Patients with low GRWR were associated with lower 1-year and 3-year survival rates compared to patients with normal GRWR, while no significant difference was found in the association of 5-year survival rate with low and normal GRWRs. Moreover, the risk of SFSS significantly increased in patients with low GRWR. Finally, no significant differences were observed in the association of low and normal GRWRs with the risk of perioperative mortality, biliary complications, postoperative bleeding, and acute rejection.

CONCLUSION

The results of this study indicated that low GRWR was associated with poor prognosis for patients following living donor liver transplantation, especially in terms of 1- and 3-year survival rates and SFSS.

Small-for-size syndrome in liver transplantation: Definition, pathophysiology and management

BACKGROUND

Since the first success in an adult patient, living donor liver transplantation (LDLT) has become an universally used procedure. Small-for-size syndrome (SFSS) is a well-known complication after partial LT, especially in cases of adult-to-adult LDLT. The definition of SFSS slightly varies among transplant physicians. The use of a partial liver graft has risks of SFSS development. Persistent portal vein (PV) hypertension and PV hyper-perfusion after LT were identified as the main factors. Hence, various approaches were explored to modulate PV flow and decrease PV pressure in order to alleviate this syndrome. Herein, the definition, clinical symptoms, pathophysiology, basic research, as well as preventive and treatment strategies for SFSS are reviewed based on an extensive review of the literature and on our own experiences.

DATA SOURCES

The articles were collected through PubMed using search terms "liver transplantation", "living donor liver transplantation", "living liver donation", "partial graft", "small-for-size graft", "small-for-size syndrome", "graft volume", "remnant liver", "standard liver volume", "graft to recipient body weight ratio", "sarcopenia", "porcine", "swine", and "rat". English publications published before March 31, 2020 were included in this review.

RESULTS

Many transplant surgeons performed PV flow modulation, including portocaval shunt, splenic artery ligation and splenectomy. With these techniques, patient outcome has been improved even when using a "small" graft. Other factors, such as preoperative recipients' nutritional and skeletal muscle status, graft congestion, and donor factors, were also identified as risk factors which all have been addressed using various strategies.

CONCLUSIONS

The surgical approach controlling PV flow and pressure could help to prevent SFSS especially in severely ill recipients. In the absence of efficacious medications to resolve SFSS, conservative treatments, including aggressive fluid balance correction for massive ascites, anti-microbiological therapy to prevent or control sepsis and intensive nutritional therapy, are all required if SFSS could not be prevented.

Living donor liver transplantation in small-for-size setting

Small-for-Size Syndrome (SFSS) is one of the most feared complication of adult split liver and living donor liver transplantation. SFSS stems from a disproportionate/excessive portal vein flow relative to the volume of the implanted liver graft, and is currently one of the major practical limits to partial liver grafts' transplantation. In the last few decades many graft inflow modulation (GIM) techniques have been proposed to curtail the portal vein flow, allowing for successful transplantation of small partial liver grafts. Graft inflow modulation techniques span from Splenic Artery Ligation (SAL), to Splenectomy, Porto-Systemic Shunts and the lately proposed Splenic Devascularization. A patient tailored approach balancing the risk of SFSS with GIM specific morbidity, is more important than identifying the ideal GIM technique. Here we summarize the most recently published data to provide general indications in the challenging preoperative choice of a GIM techniques.

Post-transplant inflow modulation for early allograft dysfunction after living donor liver transplantation

Background

To treat small-for-size syndrome (SFSS) after living donor liver transplantation (LDLT), many procedures were described for portal flow modulation before, during, or after transplantation. The selection of the procedure as well as the best timing remains controversial.

Case presentation

A 43-year-old female with end-stage liver disease underwent LDLT with extended left with caudate lobe graft from her donor who was her 41-year-old brother (graft volume/standard liver volume (GV/SLV), 35.7%; graft to recipient weight ratio (GRWR), 0.67%). During the surgery, splenectomy could not be performed owing to severe peri-splenic adhesions to avoid the ruined bleedings. The splenic artery ligation was not also completely done because it was dorsal to the pancreas and difficult to be approached. Finally, adequate portal vein (PV) inflow was confirmed after portal venous thrombectomy. As having post-transplant optional procedures that are accessible for PV flow modulation, any other procedures for PV modulation during LDLT were not done until the postoperative assessment of the graft function and PV flow for possible postoperative modulation of the portal flow accordingly. Postoperative PV flow kept as high as 30 cm/s. By the end of the 1st week, there was a progressive deterioration of the total bilirubin profile (peak as 19.4 mg/dL) and ascitic fluid amount exceeded 1000 mL/day. Therefore, splenic artery embolization was done effectively and safely on the 10th postoperative day (POD) to reverse early allograft dysfunction as PV flow significantly decreased to keep within 20 cm/s and serum total bilirubin levels gradually declined with decreased amounts of ascites below 500 mL on POD 11 and thereafter. The patient was discharged on POD 28 with good condition.

Conclusions

SFSS can be prevented or reversed by the portal inflow modulation, even by post-transplant procedure. This case emphasizes that keeping accessible angiographic treatment options for PV modulation, such as splenic artery embolization, after LDLT is quite feasible.

Approaching treatment for immunological rejection of living-donor liver transplantation in rats

Background

The anti-immunological rejection therapy for small-for-size syndrome (SFSS) after live donor liver transplantation (LDLT) play a central role in keeping graft survival. The hepatocyte number and grafts function has undergone real-time changes with the proliferation and apoptosis of the grafts after reperfusion. Lacking an accurate and effective treatment regiments or indicators to guide the use of immunosuppressive drugs in SFS liver transplantation has made immunotherapy after SFS liver transplantation an urgent problem to be solved. Herein, we established small-for-size (SFS) and normal size liver transplantation model in rats to explore the effective indicators in guiding immunotherapy, to find an effective way for overcoming SFSS.

Methods

Lewis rats (donors) and BN rats (recipients) were used to mimic allograft liver transplantation and treated with tacrolimus. Local graft immune response was analyzed through haematoxylin and eosin and immunohistochemistry. Flow cytometry was used to assess the overall immune status of recipient. The pharmacokinetics mechanism of immunosuppressive drugs was explored through detecting CYP3A2 expression at mRNA level and protein levels.

Results

The results showed the local immune reaction of SFS grafts and systemic immune responses of recipient were significantly increased compared with those in normal size grafts and their recipient at four days after liver transplantation. Regression equation was used to regulate the tacrolimus dose which not only controlled tacrolimus serum concentration effectively but alleviated liver damage and improved survival rate.

Conclusions

This study showed that AST level and tacrolimus serum concentrations are effective indicators in guiding immunotherapy. Regression equation (T_D = − 0.494T_C-0.0035AST + 260.487) based on AST and tacrolimus serum concentration can be used as a reference for adjustment of immunotherapy after SFS liver transplantation, which is applicable in clinical practice.

Conceptual changes in small-for-size graft and small-for-size syndrome in living donor liver transplantation

Early series in living donor liver transplantation (LDLT) in adults demonstrated a lower safe limit of graft volume standard liver volume ratio 25%–45%. A subsequent worldwide large LDLT series proposed a 0.8 graft recipient weight ratio (GRWR) to define small-for-size graft (SFSG) in adult LDLT. Thereafter, researchers identified innate and inevitable factors including changes in liver volume during imaging studies and graft shrinkage due to perfusion solution. Although the definition of small-for-size syndrome (SFSS) advocated in the 2000s was mainly based on prolonged cholestasis and ascites output, the term SFSS was inadequate to describe clinical manifestations possibly caused by multiple factors. Thus, the term “early allograft dysfunction (EAD),” characterized by total bilirubin >10 mg/dL or coagulopathy with international normalized ratio >1.6 on day 7, has become prevalent to describe graft dysfunction including SFSS after LDLT. Although various efforts have been made to overcome EAD in LDLT, graft selection to maintain an expected GRWR >0.8 and full venous drainage, as well as inflow modulation using splenic artery ligation, have become standard in recent LDLT.

Pre-hepatic and pre-pancreatic transplant donor evaluation

Innovations in surgical techniques coupled with advances in medical and pharmacological management in the past few decades have enabled organ transplantation to become integral to the management of end stage organ failure. In this review article, we will review the role of the radiologist in the work up of liver and pancreas donors during evaluation of their donor candidacy. The critical role of imaging in assessing the parenchymal, biliary and vascular anatomy in liver donor candidates will be reviewed, as well as highlighting the anatomical findings that may pose a contraindication to transplantation. The limited role of imaging in pancreas donor evaluation is also covered, as well as a brief overview of the surgical techniques available and how the radiologist's findings influence operative technique selection.

Outcomes of adult patients adopting small-for-size grafts in living donor liver transplantation: A systematic review and meta-analysis

BACKGROUND

Small-for-size graft (SFSG) has emerged as one of the very contentions in adult-to-adult living donor liver transplantation (LDLT) as a certain graft size is related to recipients' prognosis. Graft-to-recipient weight ratio (GRWR) ≥0.8% was considered as a threshold to conduct LDLT. However, this also has been challenged over decades as a result of technique refinements. For a better understanding of SFSG in practice, we conducted this meta-analysis to compare the perioperative outcomes and long-term outcomes between patients adopting the grafts with a lower volume (GRWR < 0.8%, SFSG group) and sufficient volume (GRWR ≥ 0.8%, non-SFSG group) in adult-to-adult LDLT.

DATA SOURCES

The studies comparing recipients adopting graft with a GRWR < 0.8% and ≥ 0.8% were searched by three authors independently in PubMed, Web of Science, Embase, the Cochrane Library, MEDLINE and Google Scholar databases until September 2018 and data were analyzed by RevMan 5.3.5.

RESULTS

Sixteen studies with a total of 3272 subjects were included in this meta-analysis. In terms of small-for-size syndrome (SFSS), no significant difference was found in subjects enrolled after year 2010 (before 2010, OR=3.00, 95% CI: 1.69-5.35, P = 0.0002; after 2010, OR=1.23, 95% CI: 0.79-1.90, P = 0.36; P for interaction: 0.02). There was no significant difference in operative duration, blood loss, cold ischemia time, biliary complications, acute rejection, postoperative bleeding, hospitalization time, perioperative mortality, and 1-, 3- and 5-year overall survival rates between two groups.

CONCLUSIONS

This meta-analysis suggested that adopting SFSG in adult LDLT has comparable outcomes to those with non-SFSG counterparts since 2010.

Coexistence of Bilirubin ≥10 mg/dL and Prothrombin Time-International Normalized Ratio ≥1.6 on Day 7: A Strong Predictor of Early Graft Loss After Living Donor Liver Transplantation

BACKGROUND

Early allograft dysfunction (EAD) defined by serum total bilirubin (TB) of 10 mg/dL or greater or prothrombin time-international normalized ratio (PT-INR) of 1.6 or greater on postoperative day 7 (POD 7) or aminotransferase greater than 2000 IU/L within the first week, is associated with early graft loss after deceased-donor liver transplantation. We aimed to determine the prognostic impact of the EAD definition in living-donor liver transplantation (LDLT).

METHODS

We analyzed the validity of the EAD definition and its impact on early graft survival in 260 adult recipients who underwent primary LDLT.

RESULTS

Eighty-four (32.3%) patients met the EAD criteria; 59 (22.7%) and 46 (17.7%) patients had TB of 10 mg/dL or greater and PT-INR of 1.6 or greater on POD 7, respectively, and 22 (8.5%) patients satisfied both criteria. Graft survival differed significantly when stratified according to TB of 10 mg/dL or greater and PT-INR of 1.6 or greater (P < 0.0001). PT-INR of 1.6 or greater resulted in higher graft mortality (risk ratio [RR], 3.87; P < 0.0001 at 90 days; RR, 2.97; P < 0.0001 at 180 days), as did TB of 10 mg/dL or greater (RR, 1.89; P = 0.027 at 90 days; RR, 1.91; P = 0.006 at 180 days). Coexistence of TB of 10 mg/dL or greater and PT-INR of 1.6 or greater was strongly associated with early graft loss (59.1%, RR, 6.97 at 90 days; 68.2%; RR, 5.75 at 180 days). In Cox regression analysis, PT-INR of 1.6 or greater and TB of 10 mg/dL or greater on POD 7 were significant risk factors for early graft loss (hazard ratio, 4.10; 95% confidence interval, 2.35-7.18; P < 0.0001, and hazard ratio, 2.43; 95% confidence interval, 1.39-4.24; P = 0.0018, respectively).

CONCLUSIONS

TB of 10 mg/dL or greater and/or PT-INR of 1.6 or greater on POD 7 predicted early graft loss after LDLT, and their coexistence worsened patient outcomes.

Pediatric Donor to Adult Recipients in Donation After Cardiac Death Liver Transplantation: A Single-Center Experience

BACKGROUND

The impact of using liver allografts from donors who are younger than 14 years at the time of donation after cardiac death (DCD) liver transplantation in terms of early allograft dysfunction (EAD) and graft survival is undefined. To determine if adults undergoing DCD liver transplantation who receive a graft from a donor age younger than or equal to 13 years have similar outcomes to recipients of organs from older than 18-year-old donors.

METHODS

Records from adult patients undergoing DCD liver transplantation between March 2012 and December 2015 who received whole grafts from donors after cardiac death were reviewed. Patients with donors younger than or equal to 13 years (group 1) and older than 18 years (group 2) were compared for EAD rates, hepatic artery thrombosis (HAT), and graft survival.

RESULTS

Records of 60 DCD liver transplantation patients were analyzed. The 90-day and 1-year graft survival rate of both groups was 90% versus 96% (P = .427) and 80% versus 84% (P = .668), respectively. The EAD rates of groups 1 and 2 were 30% versus 34% (P = .806). The incidence of HAT was 20% in group 1 compared with 12% in group 2 (P = .610). Also, 0.7% < graft to recipient weight ratio (GRWR) <0.8% was also usable for pediatric donor to adult recipients.

CONCLUSIONS

Whole liver grafts from donors younger than or equal to 13 years can potentially be used in selected size-matched (GRWR >0.7%) DCD adult recipients.

Impact of preserved collateral veins on small-for-size grafts in living donor liver transplantation

AIM

Graft size is a critical issue in living donor liver transplantation (LDLT). We hypothesized that too much portal flow could possibly be diverted into pre-existing collateral veins, alleviating small-for-size syndrome (SFSS) in LDLT. This study evaluated the impact of the preserved collateral veins in the outcomes of LDLT using a small-for-size graft.

METHODS

For patient safety, a graft-to-recipient weight ratio (GRWR) <0.8% was strictly confined to patients with collateral veins (group A), and the patient group was compared in a 1:3 ratio to a matched group of patients with GRWR ≥0.8% (group B) using propensity score analysis.

RESULTS

Forty and 120 patients were included in group A and B, respectively. No significant differences in baseline patient characteristics were observed between the two groups except for graft weight and GRWR. The lowest GRWR was 0.4%. The graft portal inflow showed no significant differences for 7 days after graft implantation, ranging from 1668 to 5100 mL/min. Small-for-size syndrome occurred in no patients (0.0%) in group A and in 10 (8.3%) in group B (P = 0.067). Overall survival rates at 1, 3, and 5 years were not different between the two groups (85.0%, 82.5%, and 82.5% vs. 92.5%, 86.7%, and 85.0%, respectively; P = 0.670).

CONCLUSION

Pre-existing collateral veins saved during surgery may have a reserve buffer for excessive portal flow to obviate SFSS in LDLT.

Liver graft-to-spleen volume ratio as a useful predictive factor of the early graft function in children and young adults transplanted for biliary atresia: a retrospective study

A graft volume/standard liver volume ratio (GV/SLV) > 35% or graft/recipient weight ratio (GRWR) > 0.8% has been considered as a standard criteria of graft selection. Even if the graft size meets these selection criteria, small-for-size syndrome can still occur depending on the portal venous flow (PVF). The aim of this study was to identify other factors contributing to portal hyperperfusion and the post-transplant course, focusing on the graft volume-to-spleen volume ratio (GV/SV). Thirty-seven BA patients who underwent living donor liver transplantation were reviewed retrospectively. First, we evaluated the preoperative factors contributing to portal hyperperfusion. Second, we evaluated the factors contributing to post-transplant complications, such as thrombocytopenia, hyperbilirubinemia, and coagulopathy. The GV/SLV was >35% in all cases; however, portal hyperperfusion (≥250 ml/min/100 g graft) was found in 12 recipients (35.3%). Furthermore, although the GRWR was >0.8% in over 90% of cases, portal hyperperfusion was found in 10 recipients (32.3%). In contrast, the GV/SV showed a significant correlation with the PVF after reperfusion. If the GV/SV was <0.88, about 80% of recipients developed portal hyperperfusion. Furthermore, the GV/SV also showed a significant correlation with post-transplant persistent thrombocytopenia and hyperbilirubinemia. The GV/SV < 0.88 predicts portal hyperperfusion, post-transplant persistent thrombocytopenia, and hyperbilirubinemia.

A new formula for estimation of standard liver volume using computed tomography-measured body thickness

The objective of this article is to derive a more accurate and easy-to-use formula for finding estimated standard liver volume (ESLV) using novel computed tomography (CT) measurement parameters. New formulas for ESLV have been emerging that aim to improve the accuracy of estimation. However, many of these formulas contain body surface area measurements and logarithms in the equations that lead to a more complicated calculation. In addition, substantial errors in ESLV using these old formulas have been shown. An improved version of the formula for ESLV is needed. This is a retrospective cohort of consecutive living donor liver transplantations from 2005 to 2016. Donors were randomly assigned to either the formula derivation or validation groups. Total liver volume (TLV) measured by CT was used as the reference for a linear regression analysis against various patient factors. The derived formula was compared with the existing formulas. There were 722 patients (197 from the derivation group, 164 from the validation group, and 361 from the recipient group) involved in the study. The donor's body weight (odds ratio [OR], 10.42; 95% confidence interval [CI], 7.25-13.60; P < 0.01) and body thickness (OR, 2.00; 95% CI, 0.36-3.65; P = 0.02) were found to be independent factors for the TLV calculation. A formula for TLV (cm³ ) was derived: 2 × thickness (mm) + 10 × weight (kg) + 190 with R² 0.48, which was the highest when compared with the 4 other most often cited formulas. This formula remained superior to other published formulas in the validation set analysis (R² , 5.37; interclass correlation coefficient, 0.74). Graft weight/ESLV values calculated by the new formula were shown to have the highest correlation with delayed graft function (C-statistic, 0.79; 95% CI, 0.69-0.90; P < 0.01). The new formula (2 × thickness + 10 × weight + 190) represents the first study proposing the use of CT-measured body thickness which is novel, easy to use, and the most accurate for ESLV. Liver Transplantation 23 1113-1122 2017 AASLD.

Summary of the British Transplantation Society UK Guidelines for Living Donor Liver Transplantation

The British Transplantation Society Guidelines for Living Donor Liver Transplantation was published in July 2015 and is the first national guideline in the field of living donor liver transplantation. The guideline aims to review the evidence relating to the evaluation process of both recipient and donor candidates; address the moral and ethical issues surrounding the procedure; outline the technical aspects of the procedure, including the middle hepatic vein controversy and the "small for size syndrome"; review donor and recipient outcomes and complications including donor mortality; and examine evidence relating to the advantages and disadvantages of living donor liver transplantation. In line with previous guidelines published by the BTS, the guideline has used the Grading of Recommendations Assessment, Development and Evaluation system to rate the strength of evidence and recommendations. This article summarizes the Statements of Recommendation contained in the guideline, which provide a framework for the delivery of living liver donation in the United Kingdom and may be of wide international interest. It is recommended that the full guideline document is consulted for details of the relevant references and evidence base. This may be accessed at http://www.bts.org.uk/BTS/Guidelines_Standards/Current/BTS/Guidelines_Standards/Current_Guidelines.aspx?hkey=e285ca32-5920-4613-ac08-fa9fd90915b5.

Small-for-size syndrome in live donor liver transplantation-Pathways of injury and therapeutic strategies

Due to the severe organ shortage and the increasing gap between the supply and demand for donor grafts, live donor liver transplantation (LDLT) has become an accepted and alternative technique for the expansion of the donor pool. However, donor safety and good recipient outcomes must be balanced regarding risk stratification and decision-making within this patient population. Small-for-size syndrome (SFSS) is one of the complications encountered after LDLT, thus increasing the burden of optimizing donor graft selection and effective treatments during its occurrence. A graft-to-recipient weight ratio (GRWR) <0.8 predisposes the graft to SFSS. However, other factors may induce this complication even without a graft-to-patient size mismatch. Several strategies to prevent this complication include portal vein flow and liver outflow modulation, as well as pharmacological treatment. Also, as an entity with a multifactorial etiology, outcomes vary between right-lobe, left-lobe, and posterior-lobe donation among series encountered in the literature. In this review, we analyze the pathophysiology and classification of this complication, the state-of-the-art on management of SFSS, and the outcomes regarding the best treatment strategy on this patient population.

Graft inflow modulation in adult-to-adult living donor liver transplantation: A systematic review

INTRODUCTION

Small-for-size syndrome (SFSS) has an incidence between 0 and 43% in small-for-size graft (SFSG) adult living donor liver transplantation (LDLT). Portal hypertension following reperfusion and the hyperdynamic splanchnic state are reported as the major triggering factors of SFSS. Intra- and postoperative strategies to prevent or to reduce its onset are still under debate. We analyzed graft inflow modulation (GIM) during adult LDLT considering the indications, efficacy of the available techniques, changes in hemodynamics and outcomes.

MATERIALS AND METHODS

A systematic literature search was performed using PubMed, EMBASE, Scopus and the Cochrane Library Central. Treatment outcomes including in-hospital mortality and morbidity, re-transplantation rate, 1-, 3-, and 5-year patient overall survival and 1-, 3-, and 5-year graft survival rates, hepatic artery and portal vein flows and pressures before and after inflow modulation were analyzed.

RESULTS

From 563 articles, 12 studies dated between 2003 and 2014 fulfilled the selection criteria and were therefore included in the study. These comprised a total of 449 adult patients who underwent inflow modulation during adult-to-adult LDLT. Types of GIM described were splenic artery ligation, splenectomy, meso-caval shunt, spleno-renal shunt, portocaval shunt, and splenic artery embolization. Mortality and morbidity ranged between 0 and 33% and 17% and 70%, respectively. Re-transplantation rates ranged between 0% and 25%. GIM was associated with good survival for both graft and recipients, reaching an 84% actuarial rate at 5 years. Through the use of GIM, irrespective of the technique, a statistically significant reduction of PVF and PVP was obtained.

CONCLUSIONS

GIM is a safe and efficient technique to avoid or limit portal hyperperfusion, especially in cases of SFSG, decreasing overall morbidity and improving outcomes.

Left lobe living donor liver transplantation in adults: What is the safety limit?

Small-for-size syndrome (SFSS) is the most significant cause of graft loss after living donor liver transplantation (LDLT), especially after left lobe (LL) LDLT in adults. The safety limit of applying LL-LDLT in adults without severe SFSS with a high rate of lethality needs to be determined. A total of 207 LL-LDLTs in adults since September 2005 were evaluated to analyze the risk factors for severe SFSS, defined as a serum total bilirubin concentration of ≥20.0 mg/dL after LDLT. Although there were no significant differences in cumulative graft survival after LDLT between medium grafts (graft volume [GV] to standard liver volume [SLV] ratio ≥ 40.0%), small grafts (35.0% ≤ GV/SLV < 40.0%), and extra small grafts (GV/SLV < 35.0%), patients with severe SFSS showed a significantly lower 5-year graft survival rate than those without (42.9% versus 94.3%, respectively; P < 0.001). Multivariate analysis for severe SFSS after LL-LDLT showed that donor age of ≥48 years (P = 0.01), Model for End-Stage Liver Disease (MELD) score of ≥ 19 (P < 0.01), and end portal venous pressure of ≥19 mm Hg (P = 0.04) were the significant and independent factors for severe SFSS after LL-LDLT. Within such high-risk subgroups of patients with a donor age of ≥48 years or MELD score of ≥ 19 before LDLT, operative blood loss volume of ≥8.0 L was a risk factor for severe SFSS. LL-LDLT in adults could be indicated and provide acceptable outcomes for the combinations of donors aged < 48 years and recipients with a MELD score of <19. Smaller grafts might yield acceptable outcomes in appropriately selected donor-recipient combinations. Liver Transplantation 22 1666-1675 2016 AASLD.

Modified Hepatic Venous Plane: A Key Factor for Improving Preoperative MDCT Donor Volume Prediction in Living-Donor Liver Transplantation

OBJECTIVE

The aim of this work was to present our experience using a modified hepatic venous plane in multidetector computerized tomography (MDCT) for reducing the discrepancy between preoperative liver volume estimation and intraoperative weight (IOW) measurement in living-donor liver transplantation (LDLT).

METHODS

We retrospectively reviewed the medical records of 57 consecutive living donors with the use of MDCT as a modality for volumetric assessment for LDLT from May 2007 to January 2015. We divided living donors into 2 groups according to surgical methods: right hepatectomy (RH) and left hepatectomy (LH). Initial liver volumetric measurement (group I) was assessed. After discussions with radiologist, the transplantation surgeon used a modified hepatic venous plane for surgical significant middle hepatic venous variants (>5 mm) in 16 living donors and applied the initial surgical plane in the remaining for the modified donor liver volumetric measurement (group II). We then compared the correlations of these 2 groups with the use of IOW.

RESULTS

The overall correlation (r) between group I and IOW was 0.947. The correlations (r) between group I and IOW were 0.872 and 0.955 for RH and LH, respectively. Compared with group I, group II showed better correlation with IOW: r = 0.949 and 0.981 for RH and LH, respectively. The overall correlation (r) between group II and IOW was 0.980, and the error ratio was 5.95 ± 5.05%.

CONCLUSIONS

Our study showed that using a modified hepatic venous plane in preoperative MDCT, after good communication between transplant surgeon and radiologist, can provide more accurate liver volume estimation and achieve a better correlation with IOW in LDLT.

Outcomes of liver transplantation with liver grafts from pediatric donors used in adult recipients

Although there is an agreement that liver grafts from pediatric donors (PDs) should ideally be used for pediatric patients, there remain situations when these grafts are turned down for pediatric recipients and are then offered to adult recipients. The present study aimed to investigate the outcomes of using these grafts for liver transplantation (LT) in adult patients. Data from all patients undergoing LT between 2002 and 2014 were obtained from the United Network for Organ Sharing Standard Analysis and Research file. Adult recipients undergoing LT were divided into 2 groups: those receiving a pediatric liver graft (pediatric-to-adult group) and those receiving a liver graft from adult donors (adult-to-adult group). A separate subgroup analysis comparing the PDs used for adult recipients and those used for pediatric recipients was also performed. Patient and graft survival were not significantly different between pediatric-to-adult and adult-to-adult groups (P = 0.08 and P = 0.21, respectively). Hepatic artery thrombosis as the cause for graft loss was higher in the pediatric-to-adult group (3.6%) than the adult-to-adult group (1.9%; P < 0.001). A subanalysis looking at the pediatric-to-adult group found that patients with a predicted graft-to-recipient weight ratio (GRWR) < 0.8 had a higher 90-day graft loss rate than those with a GRWR ≥ 0.8 (39% versus 9%; P < 0.001). PDs used for adult recipients had a higher proportion of donors with elevated aspartate aminotransferase/alanine aminotransferase (20% vs. 12%; P < 0.001), elevated creatinine (11% vs. 4%; P < 0.001), donation after cardiac death donors (12% vs. 0.9%; P < 0.001), and were hepatitis B virus core positive (1% vs. 0.3%; P = 0.002) than PDs used for pediatric recipients. In conclusion, acceptable patient and graft survival can be achieved with the use of pediatric liver grafts in adult recipients, when these grafts have been determined to be inappropriate for usage in the pediatric population. Liver Transplantation 22 1099-1106 2016 AASLD.

Small for Size and Flow (SFSF) syndrome: An alternative description for posthepatectomy liver failure

Small for Size Syndrome (SFSS) syndrome is a recognizable clinical syndrome occurring in the presence of a reduced mass of liver, which is insufficient to maintain normal liver function. A definition has yet to be fully clarified, but it is a common clinical syndrome following partial liver transplantation and extended hepatectomy, which is characterized by postoperative liver dysfunction with prolonged cholestasis and coagulopathy, portal hypertension, and ascites. So far, this syndrome has been discussed with focus on the remnant size of the liver after partial liver transplantation or extended hepatectomy. However, the current viewpoints believe that the excessive flow of portal vein for the volume of the liver parenchyma leads to over-pressure, sinusoidal endothelial damages and haemorrhage. The new hypothesis declares that in both extended hepatectomy and partial liver transplantation, progression of Small for Size Syndrome is not determined only by the "size" of the liver graft or remnant, but by the hemodynamic parameters of the hepatic circulation, especially portal vein flow. Therefore, we suggest the term "Small for Size and Flow (SFSF)" for this syndrome. We believe that it is important for liver surgeons to know the pathogenesis and manifestation of this syndrome to react early enough preventing non-reversible tissue damages.

Outcomes of adult-to-adult living donor liver transplantation in 321 recipients

We conducted a retrospective investigation in order to clarify whether selecting the type of liver graft had an impact on outcomes of adult-to-adult living donor liver transplantation (AALDLT). Data from the medical records of the donors and the recipients of 321 consecutive cases of AALDLT performed between April 2004 and March 2014 were retrospectively analyzed. Our general criteria for selecting the type of liver graft was that a left graft was preferentially selected when the estimated volume of the left graft was ≥35% of the standard liver volume of the recipient, and that a right graft was selected only when the estimated remnant liver volume of the donor was ≥35% of the total liver volume. In this series, 177 left grafts, 136 right grafts, and 8 posterior grafts were used. The left grafts tended to have 2 or more arteries, whereas the right grafts tended to have 2 or more bile duct orifices. The graft survival curves and the incidences of severe complications were comparable between the AALDLT using right grafts and the AALDLT using left grafts. The preoperative estimation of graft size hardly enabled us to predict severe posttransplant complication. Moreover, small-for-size graft syndrome occurred regardless of the estimated graft volumes. Instead, donor age was a significant risk factor for small-for-size graft syndrome. In conclusion, left grafts should be more aggressively used for the sake of donors' safety. The use of hepatic grafts from older donors should be avoided if possible in order to circumvent troublesome posttransplant complications.

Hepatic Arterial Buffer Response Maintains the Homeostasis of Graft Hemodynamics in Patient Receiving Living Donor Liver Transplantation

BACKGROUND

In living donor liver transplantation (LDLT), the hepatic hemodynamics plays important roles in graft regeneration, and the hepatic blood inflows are associated with graft size. However, the data of interplay between the hepatic arterial buffer response (HABR) and graft-to-recipient weight ratio (GRWR) in clinical LDLT are lacking.

AIMS

To identify the effect of the HABR on the hepatic hemodynamics and recovery of graft function and to evaluate the safe lower limit of the GRWR in carefully selected recipients.

METHODS

Portal venous and hepatic arterial blood flow was measured in recipients with ultrasonography, and the graft functional recovery, various complications, and survive states after LDLT were compared.

RESULTS

In total, 246 consecutive patients underwent LDLT with right lobe grafts. In total, 26 had a GRWR < 0.7 % (A), 29 had a GRWR between 0.7 and 0.8 % (B), and 181 had a GRWR > 0.8 % (C). For small-for-size syndrome, there was no significant difference (P = 0.176). Graft survival rates at 1, 3, and 5 year were not different (P = 0.710). The portal vein flow and portal vein flow per 100 g graft weight peaks were significantly higher in the A. Hepatic arterial velocity and hepatic arterial flow decreased in all the three groups on postoperative day 1; however, the hepatic arterial flow per 100 g graft weight was close to healthy controls.

CONCLUSIONS

HABR played important roles not only in the homeostasis of hepatic afferent blood supply but also in maintaining enough hepatic perfusion to the graft.

Influence of graft size matching on outcomes of infantile living donor liver transplantation

We aimed to assess the impact of size mismatching between grafts and recipients on outcomes of infants or small children after LDLT. Between October 2006 and December 2014, 129 LDLT recipients weighing no more than 8 kg were retrospectively analyzed. The entire cohort was categorized into three groups by GRWR: GRWR < 3.0% (group A, n = 38), 3.0% ≤ GRWR < 4.0% (group B, n = 61), and GRWR ≥ 4.0% (group C, n = 30). Baseline characteristics were similar among groups A, B, and C. Compared with groups A and B, post-transplant alanine aminotransferase and aspartate aminotransferase within seven days were significantly higher in group C; however, differences between total bilirubin and albumin after transplantation were not prominent. Moreover, incidences of surgical complications, perioperative deaths, infections, and acute rejections were all comparable among the three groups. Five-yr patient survival rates for groups A, B, and C were 89.5%, 88.9%, and 81.6%, respectively (p = 0.872), and the graft survival rates were 89.5%, 86.6%, and 81.6%, respectively (p = 0.846). In conclusion, GRWR between 1.9% and 5.8% would not cause noticeable adverse events for infantile LDLT recipients ≤ 8 kg. However, there is still a role for considering reduction in the graft mass as an applicable strategy in selected cases.

A novel objective method for deceased donor and recipient size matching in liver transplantation

Although the consequences of implantation of a large whole liver graft into a small recipient such as compression and compromise of graft perfusion are well known, no accepted measure to aid in donor-to-recipient size matching exists. Donor liver graft and recipient native liver weights as well as donor and recipient size and amount of ascites were investigated in 1953 patients who underwent liver transplantation using deceased donor grafts between January 2002 and July 2013. We used a previously described formula for liver resections (standardized total liver volume [sTLV] = -794.41 + 1267.28 × body surface area [m(2)]) for calculating sTLV, in the current cohort of deceased liver donors. Early allograft dysfunction (EAD) and graft survival were the primary outcome measures. The formula for calculating sTLV for liver resections was validated as an accurate predictor of liver volume in the current cohort of deceased liver donors (r(2) = 0.45; P < 0.001). A cutoff point of sTLV ratio ≥ 1.25 was determined through receiver operating characteristic curves, and patients were dichotomized into 2 groups. In the sTLV ratio ≥ 1.25 group, 50% of patients developed EAD compared to 25% of patients in the sTLV ratio < 1.25 group (P < 0.001). The proportion of patients developing graft failure within 90 days was 9.6% in the sTLV ratio ≥ 1.25 group and 5.4% in the sTLV ratio < 1.25 group (P = 0.045). This study validates the use of the sTLV for prediction of actual donor liver weight in the transplant setting. Using this formula, donors with a calculated sTLV size ratio ≥ 1.25 have an increased risk of EAD and therefore caution should be used when that value is exceeded. This adjusted size ratio can be used as a decision aid when considering donor and recipient matching with potential liver organ offers.

Current status and perspectives in split liver transplantation

Growing experience with the liver splitting technique and favorable results equivalent to those of whole liver transplant have led to wider application of split liver transplantation (SLT) for adult and pediatric recipients in the last decade. Conversely, SLT for two adult recipients remains a challenging surgical procedure and outcomes have yet to improve. Differences in organ shortages together with religious and ethical issues related to cadaveric organ donation have had an impact on the worldwide distribution of SLT. Despite technical refinements and a better understanding of the complex liver anatomy, SLT remains a technically and logistically demanding surgical procedure. This article reviews the surgical and clinical advances in this field of liver transplantation focusing on the role of SLT and the issues that may lead a further expansion of this complex surgical procedure.

Liver regeneration after living donor transplantation: adult-to-adult living donor liver transplantation cohort study

Adult-to-adult living donors and recipients were studied to characterize patterns of liver growth and identify associated factors in a multicenter study. Three hundred and fifty donors and 353 recipients in the Adult-to-Adult Living Donor Liver Transplantation Cohort Study (A2ALL) receiving transplants between March 2003 and February 2010 were included. Potential predictors of 3-month liver volume included total and standard liver volumes (TLV and SLV), Model for End-Stage Liver Disease (MELD) score (in recipients), the remnant and graft size, remnant-to-donor and graft-to-recipient weight ratios (RDWR and GRWR), remnant/TLV, and graft/SLV. Among donors, 3-month absolute growth was 676 ± 251 g (mean ± SD), and percentage reconstitution was 80% ± 13%. Among recipients, GRWR was 1.3% ± 0.4% (8 < 0.8%). Graft weight was 60% ± 13% of SLV. Three-month absolute growth was 549 ± 267 g, and percentage reconstitution was 93% ± 18%. Predictors of greater 3-month liver volume included larger patient size (donors and recipients), larger graft volume (recipients), and larger TLV (donors). Donors with the smallest remnant/TLV ratios had larger than expected growth but also had higher postoperative bilirubin and international normalized ratio at 7 and 30 days. In a combined donor-recipient analysis, donors had smaller 3-month liver volumes than recipients adjusted for patient size, remnant or graft volume, and TLV or SLV (P = 0.004). Recipient graft failure in the first 90 days was predicted by poor graft function at day 7 (HR = 4.50, P = 0.001) but not by GRWR or graft fraction (P > 0.90 for each). Both donors and recipients had rapid yet incomplete restoration of tissue mass in the first 3 months, and this confirmed previous reports. Recipients achieved a greater percentage of expected total volume. Patient size and recipient graft volume significantly influenced 3-month volumes. Importantly, donor liver volume is a critical predictor of the rate of regeneration, and donor remnant fraction affects postresection function. Liver Transpl 21:79-88, 2015. © 2014 AASLD.

Split liver transplantation using Hemiliver graft in the MELD era: a single center experience in the United States

Under the "sickest first" Model for End-Stage Liver Disease (MELD) allocation, livers amenable to splitting are most often allocated to patients unsuitable for split liver transplantation (SLT). Our experience with SLT using hemilivers was reviewed. From April 2004 to June 2012, we used 25 lobar grafts (10 left lobes and 15 right lobes) for adult-sized recipients. Twelve recipients were transplanted with primary offers, and 13 were transplanted with leftover grafts. Six grafts were shared with other centers. The data were compared with matched whole liver grafts (n = 121). In 92% of donors, the livers were split in situ. Hemiliver recipients with severe portal hypertension had a greater graft-to-recipient weight ratio than those without severe portal hypertension (1.96% vs. 1.40%, p < 0.05). Hemiliver recipients experienced biliary complications more frequently (32.0% vs. 10.7%, p = 0.01); however, the 5-year graft survival for hemilivers was comparable to whole livers (80.0% vs. 81.5%, p = 0.43). The secondary recipients with leftover grafts did not have increased incidences of graft failure (p = 0.99) or surgical complications (p = 0.43) compared to the primary recipients. In conclusion, while routine application is still controversial due to various challenges, hemiliver SLT can achieve excellent outcomes under the MELD allocation.

Small-for-size syndrome in living-donor liver transplantation using a left lobe graft

In living-donor liver transplantation with a left lobe graft, which can reduce the burden on the donor compared to right lobe graft, the main problem is small-for-size (SFS) syndrome. SFS syndrome is a multifactorial disease that includes aspects related to the graft size, graft quality, recipient factors and even technical issues. The main pathophysiology of SFS syndrome is the sinusoidal microcirculatory disturbance induced by shear stress, which is caused by excessive portal inflow into the smaller graft. The donor age, the presence of steatosis of the graft and a poor recipient status are all risk factors for SFS syndrome. To resolve SFS syndrome, portal inflow modulation, splenectomy, splenic artery modulation and outflow modulation have been developed. It is important to establish strict criteria for managing SFS syndrome. Using pharmacological interventions and/or therapeutic approaches that promote liver regeneration could increase the adequate outcomes in SFS liver transplantation. Left lobe liver transplantation could be adopted in Western countries to help resolve the organ shortage.

Clinical significance of gastrointestinal bleeding after living donor liver transplantation

The clinical presentations of gastrointestinal bleeding (GIB) occurring after living donor liver transplantation (LDLT) have not been fully described. We performed a retrospective analysis of 297 LDLT cases. Nineteen patients (6.4%) experienced GIB after LDLT. The etiology of GIB included bleeding at the jejunojejunostomy following hepaticojejunostomy (n = 13), peptic ulcer disease (n = 2), portal hypertensive gastropathy (n = 2), and other causes (n = 2). Hemostasis was achieved in 13 patients (68.4%) by endoscopic (n = 3), surgical (n = 1), or supportive treatments (n = 15), but not in the other six patients. Graft dysfunction (P < 0.001), hepaticojejunostomy (P = 0.01), portal vein pressure at the end of surgery >20 mmHg (P = 0.002), and operative blood loss >10 L (P = 0.004) were risk factors. One-year graft survival rate was significantly lower in patients with GIB than in patients without GIB (P < 0.001). The inhospital mortality rate was 52.6% for patients with GIB, 75.0% for patients with graft dysfunction, and 14.3% for patients without graft dysfunction (P = 0.028). Despite its infrequency after LDLT, GIB has strong correlation with graft dysfunction and inhospital mortality.

Graft-to-recipient weight ratio lower to 0.7% is safe without portal pressure modulation in right-lobe living donor liver transplantation with favorable conditions

BACKGROUND

The low graft-to-recipient weight ratio (GRWR) in adult-to-adult living donor liver transplantation (LDLT) is one of the major risk factors affecting graft survival. The goal of this study was to evaluate whether the lower limit of the GRWR can be safely reduced without portal pressure modulation in right-lobe LDLT.

METHODS

From 2005 to 2011, 317 consecutive patients from a single institute underwent LDLT with right-lobe grafts without portal pressure modulation. Of these, 23 had a GRWR of less than 0.7% (group A), 27 had a GRWR of ≥0.7%, <0.8% (group B), and 267 had a GRWR of more than and equal to 0.8% (group C). Medical records, including recipient, donor, operation factors, laboratory findings and complications were reviewed retrospectively.

RESULTS

The baseline demographics showed low model for end-stage liver disease score (mean 16.3+/-8.9) and high percentage of hepatocellular carcinoma (231 patients, 72.9%). Three groups by GRWR demonstrated similar characteristics except recipient body mass index and donor gender. For small-for-size syndrome, there were 3 (13.0%) in group A, 1 (3.7%) in group B, and 2 patients (0.7%) in group C (P<0.001). Hepatic artery thrombosis was more frequently observed in group A than in groups B and C (8.7% vs 3.7% vs 1.9%, P=0.047). However, among the three groups, graft survival rates at 1 year (100% vs 96.3% vs 93.6%) and 3 years (91.7% vs 73.2% vs 88.1%) were not different (P=0.539). In laboratory measurements, there was no group difference in total bilirubin and albumin. However, prothrombin time was longer in group A within postoperative 1 week and platelet count was lower in groups A and B within postoperative 1 month.

CONCLUSION

A GRWR lower to 0.7% is safe and does not need to modulate portal pressure in adult-to-adult LDLT using the right-lobe in favorable conditions including low model for end-stage liver disease score.