Somatostatin therapy protects porcine livers in small-for-size liver transplantation

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.

Current evidence on posthepatectomy liver failure: comprehensive review

INTRODUCTION

Despite important advances in many areas of hepatobiliary surgical practice during the past decades, posthepatectomy liver failure (PHLF) still represents an important clinical challenge for the hepatobiliary surgeon. The aim of this review is to present the current body of evidence regarding different aspects of PHLF.

METHODS

A literature review was conducted to identify relevant articles for each topic of PHLF covered in this review. The literature search was performed using Medical Subject Heading terms on PubMed for articles on PHLF in English until May 2022.

RESULTS

Uniform reporting on PHLF is lacking due to the use of various definitions in the literature. There is no consensus on optimal preoperative assessment before major hepatectomy to avoid PHLF, although many try to estimate future liver remnant function. Once PHLF occurs, there is still no effective treatment, except liver transplantation, where the reported experience is limited.

DISCUSSION

Strict adherence to one definition is advised when reporting data on PHLF. The use of the International Study Group of Liver Surgery criteria of PHLF is recommended. There is still no widespread established method for future liver remnant function assessment. Liver transplantation is currently the only effective way to treat severe, intractable PHLF, but for many indications, this treatment is not available in most countries.

Experimental Clinical Model of Liver Transplantation in Large White Pigs Without Venovenous Bypass: Pre-, Intra-, and Maintenance Care

BACKGROUND

Liver transplantation in an animal model is challenging due to hemodynamics and intraoperative anesthetic care. Several models are described in the literature employing different techniques such as venovenous bypass or aortic cross-clamping to maintain hemodynamic stability, although few groups keep the animal alive in the postoperative period. This study aims to evaluate a liver transplantation clinical model in pigs without venovenous bypass or aortic cross-clamping.

METHODS

Male pigs weighing 20 to 35 kg underwent liver transplantation surgery without using venovenous bypass or aorta cross-clamping. Protocols were approved by the Animal Care and Use Committee of the University of São Paulo, Brazil.

RESULTS

Ten LTs were performed. Cold ischemia and warm ischemia were 119 ± 33.28 minutes and 26 ± 9.6 minutes, respectively. Hemodynamic changes were significantly higher after the postrevasculazation phase: heart rate (P < .001), medium arterial pressure (P < .001), and cardiac output (P = .03). Hypotension was treated with intravenous fluids and, in some cases, with vasoactive drugs especially during the post-reperfusion period. No animals died during the procedure and almost survival until the first postoperative day. Serum aspartate aminotransferase and lactate increased their values in the post-reperfusion phase.

CONCLUSIONS

Practice-based on laboratory animals improves surgical skills and the development of experimental models aimed at new advances in this field. Perfecting our technique on the swine model, we could move forward to create a small-for-size model, test new therapeutic strategies, and define the boundaries for safely performing an enlarged liver resection or a partial liver graft transplant.

Small-for-Size Syndrome: Systemic Review in a Porcine Experimental Model

BACKGROUND

The small-for-size syndrome (SFSS) is characterized by prolonged hyperbilirubinemia, coagulopathy, and/or encephalopathy caused by a small liver graft that cannot sustain the metabolic demands of the recipient after a partial liver transplant (PLT). Models of PLT in pigs are excellent for studying this syndrome. This review aimed to identify the different porcine models of SFSS in the literature and compare their technical aspects and therapeutics methods focused on portal inflow modulation (PIM).

METHODS

We performed a systematic review of the porcine experimental model and SFSS. The MEDLINE-PubMed, EMBASE, Cochrane Library, LILACS, and SciELO databases were electronically searched and updated until June 20, 2021. The MeSH terms used were ''ORGAN SIZE'' AND ''LIVER TRANSPLANTATION".

RESULTS

Thirteen SFSS porcine models were reported. Four were performed with portocaval shunt to PIM and 3 with mesocaval shunt to PIM. A few studies focused on clinical therapeutics to PIM; a study described somatostatin infusion to avoid SFSS. Initially, studies on PIM showed its potentially beneficial effects without mentioning the minimum portal flow that permits liver regeneration. However, an excessive portal diversion could be detrimental to this process.

CONCLUSIONS

The use of porcine models on SFSS resulted in a better understanding of its pathophysiology and led to the establishment of various types of portal modulation, surgical techniques with different complexities, and pharmaceutical strategies such as somatostatin, making clear that without reducing the portal vein pressure the outcomes are poor. With the improvement of these techniques, SFSS can be avoided.

Somatostatin Therapy Improves Stellate Cell Activation and Early Fibrogenesis in a Preclinical Model of Extended Major Hepatectomy

Liver resection treats primary and secondary liver tumors, though clinical applicability is limited by the remnant liver mass and quality. Herein, major hepatic resections were performed in pigs to define changes associated with sufficient and insufficient remnants and improve liver-specific outcomes with somatostatin therapy. Three experimental groups were performed: 75% hepatectomy (75H), 90% hepatectomy (90H), and 90% hepatectomy + somatostatin (90H + SST). Animals were followed for 24 h (N = 6) and 5 d (N = 6). After hepatectomy, portal pressure gradient was higher in 90H versus 75H and 90H + SST (8 (3-13) mmHg vs. 4 (2-6) mmHg and 4 (2-6) mmHg, respectively, p < 0.001). After 24 h, changes were observed in 90H associated with stellate cell activation and collapse of sinusoidal lumen. Collagen chain type 1 alpha 1 mRNA expression was higher, extracellular matrix width less, and percentage of collagen-staining areas greater at 24 h in 90H versus 75H and 90H + SST. After 5 d, remnant liver mass was higher in 75H and 90H + SST versus 90H, and Ki-67 immunostaining was higher in 90H + SST versus 75H and 90H. As well, more TUNEL-staining cells were observed in 90H versus 75H and 90H + SST at 5 d. Perioperative somatostatin modified portal pressure, injury, apoptosis, and stellate cell activation, stemming changes related to hepatic fibrogenesis seen in liver remnants not receiving treatment.

Intraoperative Increase of Portal Venous Pressure is an Immediate Predictor of Posthepatectomy Liver Failure After Major Hepatectomy: A Prospective Study

OBJECTIVES

The aim of this study was to assess intraoperative changes of hepatic macrohemodynamics and their association with ascites and posthepatectomy liver failure (PHLF) after major hepatectomy.

SUMMARY OF BACKGROUND DATA

Large-scale ascites and PHLF remain clinical challenges after major hepatectomy. No study has concomitantly evaluated arterial and venous liver macrohemodynamics in patients undergoing liver resection.

METHODS

Portal venous pressure (PVP), portal venous flow (PVF), and hepatic arterial flow (HAF) were measured intraoperatively pre- and postresection in 67 consecutive patients with major hepatectomy (ie, resection of ≥3 liver segments). A group of 30 patients with minor hepatectomy served as controls. Liver macrohemodynamics and their intraoperative changes (ie, Δ) were analyzed as predictive biomarkers of ascites and PHLF using Fisher exact, t test, or Wilcoxon rank sum test for univariate and logistic regression for multivariate analyses.

RESULTS

Major hepatectomy increased PVP by 26.9% (P = 0.001), markedly decreased HAF by 40.7% (P < 0.001), and slightly decreased PVF by 13.4% (P = 0.011). Minor resections had little effects on hepatic macrohemodynamics. There was no significant association of liver macrohemodynamics with ascites. While middle hepatic vein resection caused higher postresection PVP after right hepatectomy (P = 0.04), the Pringle maneuver was associated with a significant PVF (P = 0.03) and HAF reduction (P = 0.03). Uni- and multivariate analysis revealed an intraoperative PVP increase as an independent predictor of PHLF (P = 0.025).

CONCLUSION

Intraoperative PVP kinetics serve as independent predictive biomarker of PHLF after major hepatectomy. These data highlight the importance to assess intraoperative dynamics rather than the pre- and postresection PVP values.

The beneficial impacts of splanchnic vasoactive agents on hepatic functional recovery in massive hepatectomy porcine model

Background

Excessive portal pressure after massive hepatectomy can cause hepatic sinusoidal injury and have deleterious impacts on hepatic functional recovery, contributing to developing post-hepatectomy liver failure. This study aimed to assess the effects of splanchnic vasoactive agents on hepatic functional recovery and regeneration while clarifying the underlying mechanism, using a 70% hepatectomy porcine model.

Methods

Eighteen pigs undergoing 70% hepatectomy were involved in this study and divided into three groups: control (n=6), terlipressin (n=6), and octreotide (n=6). Terlipressin (0.5 mg) and octreotide (0.2 mg) were administered 3 times a day for each group with the first dose starting just before surgery until the 7th postoperative day, at which time the surviving pigs were sacrificed. During the period, portal pressure, liver weight, biochemical analysis, histological injury score, and molecular markers were evaluated and compared between groups.

Results

The 7-day survival rates in the octreotide, terlipressin, and control groups were 100%, 83.3%, and 66.7%, respectively. The portal pressures decreased in both terlipressin and octreotide groups than the control group at 30 minutes, 1 hour and 6 hours after hepatectomy. The amount of regeneration measured by liver weight to body weight ratio at the time of sacrifice in the terlipressin group was smaller than that in the control group (117% vs. 129%, P=0.03). Serum aspartate aminotransferase (AST) and total bilirubin levels at 1 and 6 hours after hepatectomy and prothrombin time/international normalized ratio (PT/INR) at 6 hours after hepatectomy were significantly improved in the terlipressin and octreotide groups compared to the control group. Serum endothelin-1 (ET-1) was significantly lower in the terlipressin group than that in the control group 6 hours after hepatectomy (P<0.01). The histological injury score in the control group was significantly higher than that in the terlipressin group on the 7th postoperative day (P<0.01).

Conclusions

Splanchnic vasoactive agents, such as terlipressin and octreotide, could effectively decrease portal pressure and attenuate liver injury after massive hepatectomy.

Simultaneous splenectomy improves outcomes after adult living donor liver transplantation

BACKGROUND & AIMS

Small-for-size graft (SFSG) syndrome is a major cause of graft loss after living donor liver transplantation (LDLT). Splenectomy (Spx) is an option to prevent this catastrophic complication, but its effect remains controversial. Herein, we aimed to elucidate the effect of simultaneous Spx on graft function and long-term outcomes after LDLT.

METHODS

Three hundred and twenty patients were divided into 2 groups: those undergoing (n = 258) and those not undergoing (n = 62) simultaneous Spx. To overcome selection bias, propensity score matching (PSM) was performed (n = 50 in each group).

RESULTS

Before PSM, recipients undergoing simultaneous Spx showed better graft function on post-operative day (POD) 7 and 14, as well as lower sepsis frequency within 6 months after LDLT and better graft survival rates compared to those not undergoing Spx. After PSM, compared to patients not undergoing Spx, those undergoing Spx had a lower frequency of early graft dysfunction on POD 7 (p = 0.04); a lower frequency of SFSG syndrome (p = 0.01), lower serum total bilirubin levels (p = 0.001), and lower international normalized ratio (p = 0.004) on POD 14; lower sepsis frequency within 6 months after LDLT (p = 0.02), and better graft survival rates (p = 0.04). Univariate analysis revealed that not undergoing Spx (hazard ratio 3.06; 95% CI 1.07-11.0; p = 0.037) was the only risk factor for graft loss after LDLT.

CONCLUSIONS

Simultaneous Spx may prevent SFSG syndrome and is a predictive factor for graft survival after LDLT. Simultaneous Spx is recommended when a small graft (≤35% of standard liver weight) is predicted preoperatively, or for patients with portal hypertension or high portal pressure (above 20 mmHg) after reperfusion in LDLT.

LAY SUMMARY

Living donor liver transplantation (LDLT) for patients with acute or chronic liver failure is an alternative to overcome the deceased donor shortage. The potential mismatch between graft and body size is a problem that needs to be solved for LDLT recipients. Herein, we evaluated the impact of simultaneous splenectomy and showed that it was associated with favorable outcomes in patients undergoing LDLT.

Effects of propofol and sevoflurane on hepatic blood flow: a randomized controlled trial

BACKGROUND

Maintaining adequate perioperative hepatic blood flow (HBF) supply is essential for preservation of postoperative normal liver function. Propofol and sevoflurane affect arterial and portal HBF. Previous studies have suggested that propofol increases total HBF, primarily by increasing portal HBF, while sevoflurane has only minimal effect on total HBF. Primary objective was to compare the effect of propofol (group P) and sevoflurane (group S) on arterial, portal and total HBF and on the caval and portal vein pressure during major abdominal surgery. The study was performed in patients undergoing pancreaticoduodenectomy because - in contrast to hepatic surgical procedures - this is a standardized surgical procedure without potential anticipated severe hemodynamic disturbances, and it allows direct access to the hepatic blood vessels.

METHODS

Patients were randomized according to the type of anesthetic drug used. For both groups, Bispectral Index (BIS) monitoring was used to monitor depth of anesthesia. All patients received goal-directed hemodynamic therapy (GDHT) guided by the transpulmonary thermodilution technique. Hemodynamic data were measured, recorded and guided by Pulsioflex™. Arterial, portal and total HBF were measured directly, using ultrasound transit time flow measurements (TTFM) and were related to hemodynamic variables.

RESULTS

Eighteen patients were included. There was no significant difference between groups in arterial, portal and total HBF. As a result of the GDHT, pre-set hemodynamic targets were obtained in both groups, but MAP was significantly lower in group S (p = 0.01). In order to obtain these pre-set hemodynamic targets, group S necessitated a significantly higher need for vasopressor support (p < 0.01).

CONCLUSION

Hepatic blood flow was similar under a propofol-based and a sevoflurane-based anesthetic regimen. Related to the application of GDHT, pre-set hemodynamic goals were maintained in both groups, but sevoflurane-anaesthetized patients had a significantly higher need for vasopressor support.

TRIAL REGISTRATION

Study protocol number is AGO/2017/002 - EC/2017/0164. EudraCT number is 2017-000071-90. Clin.trail.gov, NCT03772106 , Registered 4/12/2018, retrospective registered.

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.

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.

Portal flow modulation in living donor liver transplantation: review with a focus on splenectomy

Small-for-size graft (SFSG) syndrome after living donor liver transplantation (LDLT) is the dysfunction of a small graft, characterized by coagulopathy, cholestasis, ascites, and encephalopathy. It is a serious complication of LDLT and usually triggered by excessive portal flow transmitted to the allograft in the postperfusion setting, resulting in sinusoidal congestion and hemorrhage. Portal overflow injures the liver directly through nutrient excess, endothelial activation, and sinusoidal shear stress, and indirectly through arterial vasoconstriction. These conditions may be attenuated with portal flow modulation. Attempts have been made to control excessive portal flow to the SFSG, including simultaneous splenectomy, splenic artery ligation, hemi-portocaval shunt, and pharmacological manipulation, with positive outcomes. Currently, a donor liver is considered a SFSG when the graft-to-recipient weight ratio is less than 0.8 or the ratio of the graft volume to the standard liver volume is less than 40%. A strategy for transplanting SFSG safely into recipients and avoiding extensive surgery in the living donor could effectively address the donor shortage. We review the literature and assess our current knowledge of and strategies for portal flow modulation in LDLT.

A novel and simple formula to predict liver mass in porcine experimental models

A primary limitation in hepatic surgery is leaving a remnant liver of adequate size and function. Experimental models have been designed to study processes of liver injury and regeneration in this context, yet a formula to accurately calculate liver mass in an animal model is lacking. This study aims to create a novel and simple formula to estimate the mass of the native liver in a species of pigs commonly used in experimental liver surgery protocols. Using data from 200 male weanling Landrace-Large White hybrid pigs, multiple linear regression analysis is used to generate the formula. Clinical features used as variables for the predictive model are body mass and length. The final formula for pig liver mass is as follows: Liver mass (g) = 26.34232 * Body mass (kg) - 1.270629 * Length (cm) + 163.0076; R² = 0.7307. This formula for porcine liver mass is simple to use and may be helpful in studies using animals of similar characteristics to evaluate restoration of liver mass following major hepatectomy.

Portal Inflow Modulation by Somatostatin After Major Liver Resection: A Pilot Study

: Major hepatectomy (MH) can lead to an increasing portal vein pressure (PVP) and to lesions of the hepatic parenchyma. Several reports have assessed the deleterious effect of a high posthepatectomy PVP on the postoperative course of MH. Thus, several surgical modalities of portal inflow modulation (PIM) have been described. As for pharmacological modalities, experimental studies showed a potential efficiency of Somatostatin to reduce PVP and flow. To our knowledge, no previous clinical reports of PIM using somatostatin are available. Herein, we report the results of PIM using somatostatin in 10 patients who underwent MH with post-hepatectomy PVP > 20 mmHg. Our results suggest Somatostatin could be considered as an efficient reversible PIM when PVP decrease is above 2.5 mmHg.

Somatostatin and the "Small-For-Size" Liver

“Small-for-size” livers arising in the context of liver resection and transplantation are vulnerable to the effects of increased portal flow in the immediate postoperative period. Increased portal flow is an essential stimulus for liver regeneration. If the rise in flow and stimulus for regeneration are excessive; however, liver failure and patient death may result. Somatostatin is an endogenous peptide hormone that may be administered exogenously to not only reduce portal blood flow but also offer direct protection to different cells in the liver. In this review article, we describe key changes that transpire in the liver following a relative size reduction occurring in the context of resection and transplantation and the largely beneficial effects that peri-operative somatostatin therapy may help achieve in this setting.

Hemodynamic changes in ALPPS influence liver regeneration and function: results from a prospective study

BACKGROUND

Excessive increase of portal flow and pressure following extended hepatectomy have been associated to insufficient growth or function of the future liver remnant (FLR), with the risk of post-hepatectomy liver failure (PHLF). We prospectively assess the influence of liver hemodynamics on FLR regeneration and function in Associating Liver Partition and Portal vein ligation for Staged hepatectomy (ALPPS).

METHODS

Twenty-three patients underwent ALPPS; liver hemodynamics were assessed throughout the procedures. Volume and function of the FLR were evaluated by angio-CT and 99mTc-Mebrofenin-scintigraphy.

RESULTS

The portal vein flow at the end of stage-1 correlated with the increase of the FLR volume (p = 0.002). Patients with portal vein pressure (PVP) < 20 mmHg and hepatic to portal vein gradients (HVPG) < 15 mmHg at the end of ALPPS-1 showed higher FLR regeneration (76.7% vs. 30.6%, p = 0.04) and function (26.7% vs. -0.13%, p = 0.02). FLR regeneration was inversely correlated with baseline FLR/Total Liver Volume (p = 0.002) and FLR/Body Weight (p = 0.02). No correlation was found between volumes and function (p = 0.13).

CONCLUSION

Liver hemodynamic stress at the end of ALPPS-1 influences the increase of the FLR volume and function, which is higher with PVP < 20 and HVPG < 15 mmHg. Liver volume overestimates liver function and could be imprecise to set stage-2 timing.

Somatostatin analogue, Octreotide, improves restraint stress-induced liver injury by ameliorating oxidative stress, inflammatory response, and activation of hepatic stellate cells

The aim of this study is to investigate the effect of somatostatin (SST) analogue, Octreotide, on some features of liver injury induced by immobilization stress (IS) in adult male albino rats. Eighteen adult male albino rats were randomly divided into three equal groups: control, IS, and Octreotide-treated stressed groups. Octreotide (40 μg/kg body weight, subcutaneously) was administrated twice daily for 8 days during the exposure to IS. Octreotide was found to reduce the IS significantly and induce elevations in the plasma level of corticosterone, liver transaminases, and tumor necrosis factor α (TNF-α) as compared with IS group. Furthermore, Octreotide administration has significantly elevated the decline in the total antioxidant capacities (TAC) and lowered the elevated malondialdehyde (MDA) levels observed with IS in the hepatic tissue. Additionally, Octreotide treatment provided protection against the histopathological changes in the stressed liver in the form of significant reduction in the mean number of degenerated hepatocytes, the area % of collagen fibers, and glial fibrillary acid protein (GFAP) immunostaining with a significant increase in the mean number of normal hepatocytes. In conclusion, stressed rats showed disturbed liver functions and its oxidant-antioxidant status with highly expression hepatic stellate cells (HSCs), which were all improved by Octreotide administration, SST analogue.

Evaluation of postoperative ascites after somatostatin infusion following hepatectomy for hepatocellular carcinoma by laparotomy: a multicenter randomized double-blind controlled trial (SOMAPROTECT)

Background

The majority of patients undergoing hepatectomy for hepatocellular carcinoma (HCC) suffer from underlying liver disease and are exposed to the risk of postoperative ascites, which is favored by an imbalance between portal venous inflow and a diminished hepatic volume. Finding a reversible, non-invasive method for modulating the portal inflow would be of interest as it could be used temporarily during the early postoperative course. Somatostatin, a well-known drug already used in several indications, may limit the risk of postoperative ascites and liver failure by decreasing portal pressure after hepatectomy for HCC in patients with underlying liver disease. We aimed to evaluate the impact of somatostatin postoperative infusion on the incidence of ascites following hepatectomy by laparotomy for HCC in patients with underlying liver disease.

Methods/design

The SOMAPROTECT study is a multicenter randomized double-blind placebo controlled phase III trial comparing two arms of patients with underlying liver disease undergoing hepatectomy for HCC by open approach. All patients will have primary abdominal drainage before closure. Patients in the experimental arm will receive a postoperative intravenous infusion of somatostatin during 6 days. Patients in the control group will receive a placebo infusion for the same duration. The primary endpoint will be the presence or absence of postoperative ascites occurring during the 90-day postoperative course, defined as ≥500 ml/24 h of fluid in the drains during at least 3 days or any ascites requiring an invasive procedure comprising percutaneous puncture or drainage. Secondary endpoints will be duration and total volume of ascites, postoperative 90-day mortality and morbidity, liver failure, acute renal failure, length of stay in intensive care unit and hospital stay. The total number of patients to be enrolled was calculated to be 152.

Discussion

Postoperative ascites remains a major issue after hepatectomy for HCC as it is associated with increased morbidity, liver and renal failure, the need for specific treatments and prolonged hospital stay. This study represents the first randomized controlled trial to assess the benefits of somatostatin on the risk of postoperative ascites after surgery for HCC.

Trial registration

NCT02799212 (ClinicalTrials.gov identifier). Registered prior to conducting the research on 9 June 2016.

Effects of splanchnic vasoconstrictors on liver regeneration and survival after 90% rat hepatectomy

Purpose

Posthepatectomy liver failure is a serious complication and considered to be caused by increased portal pressure and flow. Splanchnic vasoactive agents and propranolol are known to decrease portal pressure. The aim of this study was to identify optimal candidates with potential for clinical use among somatostatin, terlipressin, and propranolol using rats with 90% hepatectomy.

Methods

Rats were divided into 5 groups: sham operation (n = 6), control (n = 20), propranolol (n = 20), somatostatin (n = 20), and terlipressin group (n = 20). Seven-day survival rates and portal pressure change were measured, and biochemical, histologic, and molecular analyses were performed.

Results

Portal pressure was significantly decreased in all 3 treatment groups compared to control. All treatment groups showed a tendency of decreased liver injury markers, and somatostatin showed the most prominent effect at 24 hours postoperatively. Histologic liver injury at 24 hours was significantly decreased in propranolol and terlipressin groups (P = 0.016, respectively) and somatostatin group showed borderline significance (P = 0.056). Hepatocyte proliferation was significantly increased after 24 hours in all treatment groups. Median survival was significantly increased in terlipressin group compared to control group (P < 0.01).

Conclusion

Terlipressin is considered as the best candidate, while somatostatin has good potential for clinical use, considering their effects on portal pressure and subsequent decrease in liver injury and increase in liver regeneration.

Preconditioning by portal vein embolization modulates hepatic hemodynamics and improves liver function in pigs with extended hepatectomy

BACKGROUND

Portal vein embolization is performed weeks before extended hepatic resections to increase the future liver remnant and prevent posthepatectomy liver failure. Portal vein embolization performed closer to the operation also could be protective, but worsening of portal hyper-perfusion is a major concern. We determined the hepatic hemodynamic effects of a portal vein embolization performed 24 hours prior to hepatic operation.

METHODS

An extended (90%) hepatectomy was performed in swine undergoing (portal vein embolization) or not undergoing (control) a portal vein embolization 24 hours earlier (n = 10/group). Blood tests, hepatic and systemic hemodynamics, hepatic function (plasma disappearance rate of indocyanine green), liver histology, and volumetry (computed tomographic scanning) were assessed before and after the hepatectomy. Hepatocyte proliferating cell nuclear antigen expression and hepatic gene expression also were evaluated.

RESULTS

Swine in the control and portal vein embolization groups maintained stable systemic hemodynamics and developed similar increases of portal blood flow (302 ± 72% vs 486 ± 92%, P = .13). Portal pressure drastically increased in Controls (from 9.4 ± 1.3 mm Hg to 20.9 ± 1.4 mm Hg, P < .001), while being markedly attenuated in the portal vein embolization group (from 11.4 ± 1.5 mm Hg to 16.1 ± 1.3 mm Hg, P = .061). The procedure also improved the preservation of the hepatic artery blood flow, liver function, and periportal edema. These effects occurred in the absence of hepatocyte proliferation or hepatic growth and were associated with the induction of the vasoprotective gene Klf2.

CONCLUSION

Portal vein embolization preconditioning represents a potential hepato-protective strategy for extended hepatic resections. Further preclinical studies should assess its medium-term effects, including survival. Our study also supports the relevance of hepatic hemodynamics as the main pathogenetic factor of post-hepatectomy liver failure.

Stereological analysis of size and density of hepatocytes in the porcine liver

The porcine liver is frequently used as a large animal model for verification of surgical techniques, as well as experimental therapies. Often, a histological evaluation is required that include measurements of the size, nuclearity or density of hepatocytes. Our aims were to assess the mean number-weighted volume of hepatocytes, the numerical density of hepatocytes, and the fraction of binuclear hepatocytes (BnHEP) in the porcine liver, and compare the distribution of these parameters among hepatic lobes and macroscopic regions of interest (ROIs) with different positions related to the liver vasculature. Using disector and nucleator as design-based stereological methods, the morphometry of hepatocytes was quantified in seven healthy piglets. The samples were obtained from all six hepatic lobes and three ROIs (peripheral, paracaval and paraportal) within each lobe. Histological sections (thickness 16 μm) of formalin-fixed paraffin-embedded material were stained with the periodic acid-Schiff reaction to indicate the cell outlines and were assessed in a series of 3-μm-thick optical sections. The mean number-weighted volume of mononuclear hepatocytes (MnHEP) in all samples was 3670 ± 805 μm³ (mean ± SD). The mean number-weighted volume of BnHEP was 7050 ± 2550 μm³ . The fraction of BnHEP was 4 ± 2%. The numerical density of all hepatocytes was 146 997 ± 15 738 cells mm^-3 of liver parenchyma. The porcine hepatic lobes contained hepatocytes of a comparable size, nuclearity and density. No significant differences were identified between the lobes. The peripheral ROIs of the hepatic lobes contained the largest MnHEP with the smallest numerical density. The distribution of a larger MnHEP was correlated with a larger volume of BnHEP and a smaller numerical density of all hepatocytes. Practical recommendations for designing studies that involve stereological evaluations of the size, nuclearity and density of hepatocytes in porcine liver are provided.

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.

Size mismatch in liver transplantation

Size mismatch is an unique and inevitable but critical issue in live donor liver transplantation. Unmatched metabolic demand of recipient as well as physiologic mismatch aggravates the damage to liver graft, inevitably leading to graft failure on recipient. Also, an excessive resection of liver graft for better recipient outcome in live donor liver transplant may jeopardize the healthy donor well-being and even put donor life in danger. There is a fine balance between resected graft volume required to meet the recipient's metabolic demand and residual graft volume required for donor safety. The obvious clinical necessity of finding that balance has prompted a clinical need and promoted the improvement of knowledge and development of management strategies for size-mismatched transplants. The development of the size-matching methodology has significantly improved graft outcome and recipient survival in live donor liver transplants. On the other hand, the effect of size mismatch in cadaveric transplants has never been observed as being so pronounced. The importance of matching of the donor recipient size has been unrecognized in cadaveric liver transplant. In this review, we attempt to summarize the current most updated knowledge on the subject, particularly addressing the definition and complications of size-mismatched cadaveric liver transplant, as well as management strategies.

Living donor liver transplantation in Europe

Living donor liver transplantation (LDLT) sparked significant interest in Europe when the first reports of its success from USA and Asia were made public. Many transplant programs initiated LDLT and some of them especially in Germany and Belgium became a point of reference for many patients and important contributors to the advancement of the field. After the initial enthusiasm, most of the European programs stopped performing LDLT and today the overall European activity is concentrated in a few centers and the number of living donor liver transplants is only a single digit fraction of the overall number of liver transplants performed. In this paper we analyse the present European activities and highlight the European contribution to the advancement of the field of LDLT.