Acute kidney injury and post-reperfusion syndrome in liver transplantation

Impact of Hyperoxia after Graft Reperfusion on Lactate Level and Outcomes in Adults Undergoing Orthotopic Liver Transplantation

BACKGROUND

Hyperoxia is common during liver transplantation (LT), without being supported by any guidelines. Recent studies have shown the potential deleterious effect of hyperoxia in similar models of ischemia-reperfusion. Hyperoxia after graft reperfusion during orthotopic LT could increase lactate levels and worsen patient outcomes.

METHODS

We conducted a retrospective and monocentric pilot study. All adult patients who underwent LT from 26 July 2013 to 26 December 2017 were considered for inclusion. Patients were classified into two groups according to oxygen levels before graft reperfusion: the hyperoxic group (PaO₂ > 200 mmHg) and the nonhyperoxic group (PaO₂ < 200 mmHg). The primary endpoint was arterial lactatemia 15 min after graft revascularization. Secondary endpoints included postoperative clinical outcomes and laboratory data.

RESULTS

A total of 222 liver transplant recipients were included. Arterial lactatemia after graft revascularization was significantly higher in the hyperoxic group (6.03 ± 4 mmol/L) than in the nonhyperoxic group (4.81 ± 2 mmol/L), p < 0.01. The postoperative hepatic cytolysis peak, duration of mechanical ventilation and duration of ileus were significantly increased in the hyperoxic group.

CONCLUSIONS

In the hyperoxic group, the arterial lactatemia, the hepatic cytolysis peak, the mechanical ventilation and the postoperative ileus were higher than in the nonhyperoxic group, suggesting that hyperoxia worsens short-term outcomes and could lead to increase ischemia-reperfusion injury after liver transplantation. A multicenter prospective study should be performed to confirm these results.

Prognostic Value of the Red Blood Cell Distribution Width-to-Albumin Ratio in Critically Ill Older Patients with Acute Kidney Injury: A Retrospective Database Study

Background. There is no evidence suggesting that red blood cell distribution width-to-albumin ratio (RA) predicts outcomes in severely ill older individuals with acute kidney injury (AKI). We hypothesized that RA is associated with all-cause mortality in critically ill older patients with AKI. Methods. We recorded demographics, laboratory tests, comorbidities, vital signs, and other clinical information from the MIMIC-III V1.4 dataset. The primary endpoint was 90-day all-cause mortality, and the secondary endpoints were 30-day mortality, one-year mortality, renal replacement treatment (RRT), duration of stay in the intensive care unit (ICU), sepsis, and septic shock. We generated Cox proportional hazards and logistic regression models to determine RA’s prognostic values and subgroup analyses to determine the subgroups’ mortality. We conducted a Pearson correlation analysis on RA and C-reactive protein (CRP) in the cohort of patients from the Second Affiliated Hospital of Wenzhou Medical University. Results. A total of 6,361 patients were extracted from MIMIC-III based on the inclusion and exclusion criteria. RA levels directly and linearly correlated with 90-day all-cause mortality. After controlling for ethnicity, gender, age, and other confounding variables in multivariate analysis, higher RA was significantly associated with an increased risk of 30-day, 90-day, and one-year all-cause mortality as opposed to the reduced levels of RA (tertile 3 vs. tertile 1: hazard ratios (HRs), 95% confidence intervals (CIs): 1.70, 1.43–2.01; 1.90, 1.64–2.19; and 1.95, 1.72–2.20, respectively). These results suggested that elevated levels of RA were linked to an elevated risk of 30-day, 90-day, and one-year all-cause death. There was a similar trend between RA and the use of RRT, length of stay in ICUs, sepsis, and septic shock. The subgroup analysis did not reveal any considerable interplay among strata. When areas under the curve were compared, RA was a weaker predictor than the SAPS II score but a stronger predictor than red blood cell distribution width (RDW) or albumin alone ( $P<0.001$ ); RA combined with SAPS II has better predictive power than SAPS II alone ( $P<0.001$ ). The Second Affiliated Hospital of Wenzhou Medical University cohort showed that CRP positively correlated with RA, with a coefficient of 0.2607 ( $P<0.001$ ). Conclusions. RA was an independent prognostic predictor in critically ill older patients with AKI, and greater RA was linked to a higher probability of death. The risk of AKI is complicated when RRT occurs; sepsis and septic shock increase with RA levels.

Lack of furosemide responsiveness predict severe acute kidney injury after liver transplantation

Acute kidney injury (AKI) remains to be a common but severe complication after liver transplantation (LT). However, there are still few clinically validated biomarkers. A total of 214 patients who underwent routine furosemide (1-2 mg/kg) after LT were retrospectively included. The urine output during the first 6 h was recorded to evaluate the predictive value of AKI stage 3 and renal replacement therapy (RRT). 105 (49.07%) patients developed AKI, including 21 (9.81%) progression to AKI stage 3 and 10 (4.67%) requiring RRT. The urine output decreased with the increasing severity of AKI. The urine output of AKI stage 3 did not significantly increase after the use of furosemide. The area under the receiver operator characteristic (ROC) curves for the total urine output in the first hour to predict progression to AKI stage 3 was 0.94 (p < 0.001). The ideal cutoff for predicting AKI progression during the first hour was a urine volume of less than 200 ml with a sensitivity of 90.48% and specificity of 86.53%. The area under the ROC curves for the total urine output in the six hours to predict progression to RRT was 0.944 (p < 0.001). The ideal cutoff was a urine volume of less than 500 ml with a sensitivity of 90% and specificity of 90.91%. Severe AKI after liver transplantation seriously affects the outcome of patients. Lack of furosemide responsiveness quickly and accurately predict AKI stage 3, and patients requiring RRT after the operation.

Predicting Risk Factors of Acute Kidney Injury in the First 7 Days after Admission: Analysis of a Group of Critically Ill Patients

Background

Acute kidney injury (AKI) is a common complication in critically ill patients. Some predictive models have been reported, but the conclusions are controversial. The aim of this study was the formation of nomograms to predict risk factors for AKI in critically ill patients within the first 7 days after admission to the intensive care unit (ICU).

Methods

Data were extracted from the Medical Information Mart for Intensive Care- (MIMIC-) III database. The random forest method was used to fill in the missing values, and least absolute shrinkage and selection operator (Lasso) regression analysis was performed to screen for possible risk factors.

Results

A total of 561 patients were enrolled. Complication with AKI is significantly associated with a longer length of stay (LOS). For all patients, the predictors contained in the prediction nomogram included hypertension, coronary artery disease (CAD), cardiopulmonary bypass (CPB), coronary artery bypass grafting (CABG), Simplified Acute Physiology Score II (SAPS II), central venous pressure (CVP) measured for the first time after admission, and maximum and minimum mean artery pressure (MAP). The model showed good discrimination (C - index = 0.818, 95% CI: 0.779-0.857). In the subgroup of patients with well-controlled blood glucose levels, the significant predictors included hypertension, CABG, CPB, SAPS II, and maximum and minimum MAP. Good discrimination was also present before (C - index = 0.785, 95% CI: 0.736-0.834) and after adjustment (adjusted C - index = 0.770).

Conclusion

Hypertension, CAD, CPB, CABG, SAPS II, CVP measured for the first time after admission, and maximum and minimum MAP were independent risk factors for AKI in critically ill patients.

Postoperative Blood Pressure Deficit and Acute Kidney Injury After Liver Transplant

OBJECTIVES

Acute kidney injury is a common cause of morbidity in liver transplant recipients. In critically ill patients who received an orthotopic liver transplant, we examined whether those with acute kidney injury had a greater deficit between pretransplant and posttransplant hemodynamic pressure-related parameters compared with those without acute kidney injury in the early postoperative period.

MATERIALS AND METHODS

We included patients who underwent an orthotopic liver transplant during the study period. We obtained premorbid and intensive care unit time-weighted average values for hemodynamic pressure-related parameters (systolic, diastolic, and mean arterial pressure; central venous pressure; mean perfusion pressure; and diastolic perfusion pressure) and calculated deficits in those values. We defined acute kidney injury progression as an increase of ≥1 Kidney Disease: Improving Global Outcomes stage.

RESULTS

We included 150 eligible transplantrecipients, with 88 (59%) having acute kidney injury progression. Acute kidney injury was associated with worse clinical outcomes. All achieved pressure-related values were similar between transplant recipients with or without acute kidney injury progression. However, those with acute kidney injury versus those without progression had greater diastolic perfusion pressure deficit at 12 hours (-8.33% vs 1.93%; P = .037) and 24 hours (-7.38% vs 5.11%; P = .002) and increased central venous pressure at 24 hours (46.13% vs 15%; P = .043) and 48 hours (40% vs 20.87%; P = .039).

CONCLUSIONS

Patients with acute kidney injury progression had a greater diastolic perfusion pressure deficit and increased central venous pressure compared with patients without progression. Such deficits might be modifiable risk factors for the prevention of acute kidney injury progression.

Perioperative anesthesia management in pediatric liver transplant recipient with atrial septal defect: A case report

BACKGROUND

Preoperative conditions in pediatric liver transplant recipients are understandably complex. Compared with adults, children have lesser compensatory abilities and demand greater precision during procedural executions. In the setting of end-stage liver disease, the heightened perioperative risk of coexistent cardiovascular pathology may impact graft survival as well. Requirements for anesthesia and perioperative management are thus more rigorous, calling for individualized treatments that reflect specific cardiovascular constraints and proposed surgical plans.

CASE SUMMARY

Reports of perioperative anesthesia management and liver transplant prognostication in pediatric patients with concurrent atrial septal defects are scarce. Herein, we detail the course of liver transplantation in a child with dual afflictions, focusing on perioperative anesthesia management and the important contributions of the anesthesiologist (pre- and perioperatively) to a positive therapeutic outcome, despite the clinical hurdles imposed.

CONCLUSION

Children with atrial septal defects bear substantially more than customary perioperative risk during orthotopic liver transplants, given their compromised cardiopulmonary reserves and functional states. Comprehensive preoperative cardiovascular assessments, including use of agitated-saline contrast echocardiography (to characterize intracardiac shunting) and multidisciplinary deliberation, may offer insights into structural cardiac pathophysiologic effects and transplant-related hemodynamic changes that impact new grafts. At the same time, active and effective monitoring and other measures should be taken to maintain hemodynamic stability in the perioperative period, avoid entry of bubbles into the circulation, and ease congestion in newly grafted livers. Such efforts are crucial for transplantation success and graft survival.

Liver Graft Proteomics Reveals Potential Incipient Mechanisms behind Early Renal Dysfunction after Liver Transplantation

Acute kidney injury (AKI) is frequent after liver transplantation (LT) and correlates with later development of chronic kidney disease. Its etiology is multifactorial and combines pre-, intra-, and postoperative factors. Additionally, the liver graft itself seems an important element in the development of AKI, yet the detailed mechanisms remain unclear. We hypothesized that grafts of LT recipients developing significant early AKI may show distinct proteomic alterations, and we set out to identify proteome differences between LT recipients developing moderate or severe AKI (n = 7) and LT recipients without early renal injury (n = 7). Liver biopsies obtained one hour after reperfusion were assessed histologically and using quantitative proteomics. Several cytokines and serum amyloid A2 (SAA2) were analyzed in serum samples obtained preoperatively, 2−4 h, and 20−24 h after graft reperfusion, respectively. LT induced mild histological alterations without significant differences between groups but uniformly altered liver function tests peaking on postoperative day 1, with a trend towards more severe alterations in patients developing AKI. Global quantitative proteomic analysis revealed 136 proteins differing significantly in their expression levels (p < 0.05, FC 20%): 80 proteins had higher and 56 had lower levels in the AKI group. Most of these proteins were related to immune and inflammatory responses, host defense, and neutrophil degranulation. No differences between the studied pro- and anti-inflammatory cytokines or SAA2 between groups were found at any moment. Our results suggest that grafts of LT patients who develop early AKI reveal a distinct proteome dominated by an early yet prominent activation of the innate immunity. These findings support the hypothesis that AKI after LT may be favored by certain graft characteristics.

Perioperative fluid management and outcomes in adult deceased donor liver transplantation - A systematic review of the literature and expert panel recommendations

BACKGROUND

Fluid management practices during and after liver transplantation vary widely among centers despite better understanding of the pathophysiology of end-stage liver disease and of the effects of commonly used fluids. This reflects a lack of high quality trials in this setting, but also provides a rationale for both systematic review of all relevant studies in liver recipients and evaluation of new evidence from closely related domains, including hepatology, non-transplant abdominal surgery, and critical care.

OBJECTIVES

To develop evidence-based recommendations for perioperative fluid management to optimize immediate and short-term outcomes following liver transplantation.

DATA SOURCES

Ovid MEDLINE, Embase, Scopus, Google Scholar, and Cochrane Central.

METHODS

Systematic review following PRISMA guidelines and recommendations using the GRADE approach derived from an international expert panel. Studies included those evaluating the following postoperative outcomes: acute kidney injury, respiratory complications, operative blood loss/red cell units required, and intensive care length of stay. PROSPERO protocol ID: CRD42021241392 RESULTS: Following expert panel review, 18 of 1624 screened studies met eligibility criteria for inclusion in the final quantitative synthesis. These included six single center RCTs, 11 single center observational studies, and one observational study comparing centers with different fluid management techniques. Definitions of interventions and outcomes varied between studies. Recommendations are therefore based substantially on expert opinion and evidence from other clinical settings.

CONCLUSIONS

A moderately restrictive or "replacement only" fluid regime is recommended, especially during the dissection phase of the transplant procedure. Sustained hypervolemia, based on absence of fluid responsiveness, elevated filling pressures and/or echocardiographic findings, should be avoided (Quality of Evidence: Moderate | Grade of Recommendation: Weak for restrictive fluid regime. Strong for avoidance of hypervolemia). Mean Arterial Pressure (MAP) should be maintained at >60-65 mmHg in all cases (Quality of Evidence: Low | Grade of Recommendation: Strong). There is insufficient evidence in this population to support preferential use of any specific colloid or crystalloid for routine volume replacement. However, we recommend against the use of 130/.4 HES given the high incidence of AKI in this population.

How useful is the machine perfusion in liver transplantation? An answer from a national survey

Machine perfusion (MP) has been shown worldwide to offer many advantages in liver transplantation, but it still has some gray areas. The purpose of the study is to evaluate the donor risk factors of grafts, perfused with any MP, that might predict an ineffective MP setting and those would trigger post-transplant early allograft dysfunction (EAD). Data from donors of all MP-perfused grafts at six liver transplant centers have been analyzed, whether implanted or discarded after perfusion. The first endpoint was the negative events after perfusion (NegE), which is the number of grafts discarded plus those that were implanted but lost after the transplant. A risk factor analysis for NegE was performed and marginal grafts for MP were identified. Finally, the risk of EAD was analyzed, considering only implanted grafts. From 2015 to September 2019, 158 grafts were perfused with MP: 151 grafts were implanted and 7 were discarded after the MP phase because they did not reach viability criteria. Of 151, 15 grafts were lost after transplant, so the NegE group consisted of 22 donors. In univariate analysis, the donor risk index >1.7, the presence of hypertension in the medical history, static cold ischemia time, and the moderate or severe macrovesicular steatosis were the significant factors for NegE. Multivariate analysis confirmed that macrosteatosis >30% was an independent risk factor for NegE (odd ratio 5.643, p = 0.023, 95% confidence interval, 1.27–24.98). Of 151 transplanted patients, 34% experienced EAD and had worse 1- and 3-year-survival, compared with those who did not face EAD (NoEAD), 96% and 96% for EAD vs. 89% and 71% for NoEAD, respectively (p = 0.03). None of the donor/graft characteristics was associated with EAD even if the graft was moderately steatotic or fibrotic or from an aged donor. For the first time, this study shows that macrovesicular steatosis >30% might be a warning factor involved in the risk of graft loss or a cause of graft discard after the MP treatment. On the other hand, the MP seems to be useful in reducing the donor and graft weight in the development of EAD.

[Kidney failure after liver transplantation]

One third of cirrhotic patients present impaired kidney function. It has multifactorial causes and has a harmful effect on patients' morbi-mortality before and after liver transplant. Kidney function does not improve in all patients after liver transplantation and liver-transplant recipients are at high risk of developing chronic kidney disease. Causes for renal dysfunction can be divided in three groups: preoperative, peroperative and postoperative factors. To date, there is no consensus for the modality of evaluation the risk for chronic kidney disease after liver transplantation, and for its prevention. In the present review, we describe the outcome of kidney function after liver transplantation, and the prognostic factors of chronic kidney disease to determine a risk stratification for each patient. Furthermore, we discuss therapeutic options to prevent kidney dysfunction in this setting, and highlight the indications of combined liver-kidney transplantation.

Literature review of the mechanisms of acute kidney injury secondary to acute liver injury

People exposed to liver ischaemia reperfusion (IR) injury often develop acute kidney injury and the combination is associated with significant morbidity and mortality. Molecular mediators released by the liver in response to IR injury are the likely cause of acute kidney injury (AKI) in this setting, but the mediators have not yet been identified. Identifying the mechanism of injury will allow the identification of therapeutic targets which may modulate both liver IR injury and AKI following liver IR injury.

Prognosis of liver transplantation: Does postoperative ileus matter?

Background

Nowadays, liver transplantation has become a main therapy for end-stage liver disease. However, studies show that there are high mortality and severe complications after liver transplantation. Although gastrointestinal dysfunction is a common and major complication after liver transplantation, there was rarely relative research. This study aims to elucidate the factors about ileus after liver transplantation and patients’ survival.

Methods

We collected and analyzed the data (n = 318, 2016–2019) from the First Affiliated Hospital of Xi’an Jiaotong University. After excluding cases, a total of 293 patients were included for this study. The subjects were divided into a non-ileus group and an ileus group. We reviewed 38 variables (including preoperative, operative and postoperative relative factors). Additionally, other complications after liver transplantation and survival data were compared between two groups.

Results

Of the 293 patients, 23.2% (n = 68) experienced postoperative ileus. Ileus patients were not different with non-ileus patients in preoperative, operative and postoperative factors. HBV-positive patients with ileus had a lower MELD score (P = 0.025), and lower postoperative total bilirubin was correlated with ileus (P = 0.049). Besides, Child–Pugh score of HCC patients with ileus was low (P = 0.029). The complications after liver transplantation were not different between two groups. Compared with the patients without ileus, the patients with ileus had a higher mortality rate.

Conclusion

According to our research, ileus-patients had a lower 1-year survival rates. The preoperative MELD score and postoperative total bilirubin of HBV-positive patients with ileus were lower, and Child–Pugh score of HCC patients with ileus was also lower.

How to Preserve Liver Grafts From Circulatory Death With Long Warm Ischemia? A Retrospective Italian Cohort Study With Normothermic Regional Perfusion and Hypothermic Oxygenated Perfusion

BACKGROUND

Donation after circulatory death (DCD) in Italy, given its 20-min stand-off period, provides a unique bench test for normothermic regional perfusion (NRP) and dual hypothermic oxygenated machine perfusion (D-HOPE).

METHODS

We coordinated a multicenter retrospective Italian cohort study with 44 controlled DCD donors, who underwent NRP, to present transplant characteristics and results. To rank our results according to the high donor risk, we matched and compared a subgroup of 37 controlled DCD livers, preserved with NRP and D-HOPE, with static-preserved controlled DCD transplants from an established European program.

RESULTS

In the Italian cohort, D-HOPE was used in 84% of cases, and the primary nonfunction rate was 5%. Compared with the matched comparator group, the NRP + D-HOPE group showed a lower incidence of moderate and severe acute kidney injury (stage 2: 8% versus 27% and stage 3: 3% versus 27%; P = 0.001). Ischemic cholangiopathy remained low (2-y proportion free: 97% versus 92%; P = 0.317), despite the high-risk profile resulting from the longer donor warm ischemia in Italy (40 versus 18 min; P < 0.001).

CONCLUSIONS

These data suggest that NRP and D-HOPE yield good results in DCD livers with prolonged warm ischemia.

Kidney Failure after Liver Transplantation

One-third of patients with cirrhosis present kidney failure (AKI and CKD). It has multifactorial causes and a harmful effect on morbidity and mortality before and after liver transplantation. Kidney function does not improve in all patients after liver transplantation, and liver transplant recipients are at a high risk of developing chronic kidney disease. The causes of renal dysfunction can be divided into three groups: pre-operative, perioperative and post-operative factors. To date, there is no consensus on the modality to evaluate the risk of chronic kidney disease after liver transplantation, or for its prevention. In this narrative review, we describe the outcome of kidney function after liver transplantation, and the prognostic factors of chronic kidney disease in order to establish a risk categorization for each patient. Furthermore, we discuss therapeutic options to prevent kidney dysfunction in this context, and highlight the indications of combined liver–kidney transplantation.

Chronic Kidney Disease as a Systemic Inflammatory Syndrome: Update on Mechanisms Involved and Potential Treatment

Chronic kidney disease (CKD) is characterized by manifestations and symptoms involving systemic organs and apparatus, associated with elevated cardiovascular morbidity and mortality, bone disease, and other tissue involvement. Arterial hypertension (AH), diabetes mellitus (DM), and dyslipidemia, with glomerular or congenital diseases, are the traditional risk factors recognized as the main causes of progressive kidney dysfunction evolving into uremia. Acute kidney injury (AKI) has recently been considered an additional risk factor for the worsening of CKD or the development of CKD de novo. Evidence underlies the role of systemic inflammation as a linking factor between AKI and CKD, recognizing the role of inflammation in AKI evolution to CKD. Moreover, abnormal increases in oxidative stress (OS) and inflammatory status in CKD seem to exert an important pathogenetic role, with significant involvement in the clinical management of this condition. With our revision, we want to focus on and update the inflammatory mechanisms responsible for the pathologic conditions associated with CKD, with particular attention on the development of AKI and AKI-CKD de novo, the alteration of calcium-phosphorus metabolism with bone disease and CKD-MBD syndrome, the status of malnutrition and malnutrition-inflammation complex syndrome (MICS) and protein-energy wasting (PEW), uremic sarcopenia, the status of OS, and the different inflammatory pathways, highlighting a new approach to CKD. The depth comprehension of the mechanisms underlying the development of inflammation in CKD may present new possible therapeutic approaches in CKD and hopefully improve the management of correlated morbidities and provide a reduction in associated mortality.

Biomarkers for detecting and improving AKI after liver transplantation: From diagnosis to treatment

Orthotopic liver transplantation (OLT) is a well-established treatment for patients with liver failure. The shortage of donor organs and postoperative complications remain major obstacles for improving patient survival. Among these complications, acute kidney injury (AKI) is one of the most frequent types, contributing to graft loss. The timely detection and reversal of AKI can reduce its adverse influences on graft and patient outcomes. Traditional markers for detecting AKI are often limited with regard to their accuracy and specificity, and the discovery of better AKI markers and therapeutic targets assumes great importance. During past decades, studies directed toward early detection and treatment of AKI in OLT have been available. This review summarizes the evidence of these biomarkers for the prediction, diagnosis, treatment and prognosis stratification of AKI associated with OLT.

Delayed Calcineurin Inhibitor Introduction Without Antibody Induction in Liver Transplantation Is Safe and Helps Preserve Kidney Function

INTRODUCTION

Acute kidney injury (AKI) is common after liver transplantation and affects outcome after liver transplantation. Antibody induction is commonly used to reduce dose and/or to delay introduction of calcineurin inhibitor (CNI) but is very expensive. We propose a modified immunosuppressive protocol that delays administration of CNI for 48 to 72 hours without antibody induction. This study evaluates the results of our new protocol.

MATERIAL AND METHODS

A retrospective case-control study was performed. Study patients had induction with steroid and mycophenolate mofetil without antibody induction, and CNI administration was delayed for 48 to 72 hours. Control patients received CNI and steroid induction without antibody induction, and CNI was continued posttransplant. AKI was defined as an increase in serum creatinine level of at least 1.5 times the pretransplant baseline within the first postoperative week.

RESULTS

Sixty liver transplant recipients from 2013 to 2015 were included in this study (30 in the delayed CNI group and 30 in the control group). The patient characteristics and intraoperative factors were comparable in both groups. AKI developed in 11 patients in the study group and in 20 patients in the control group (37% vs 66.7%; P = .02). There was no acute rejection observed in the first month in either group.

CONCLUSION

We have demonstrated that delayed CNI introduction without antibody induction is safe and helps preserve kidney function. Antibody induction can be omitted safely in a delayed CNI introduction protocol to reduce the cost of liver transplantation without increasing the risk of acute rejection.

Immunosuppression in Donation After Circulatory Death Liver Transplantation: Can Induction Modify Graft Survival?

Recipients of donation after circulatory death (DCD) LTs historically have an increased risk of graft failure. Antibody induction (AI) with antithymocyte globulin (ATG) or anti-interleukin 2 receptor (anti-IL2R) immunotherapy may decrease the incidence of graft failure by mitigating ischemia/reperfusion injury. A retrospective review of the United Network for Organ Sharing (UNOS) database for LTs between 2002 and 2015 was conducted to determine whether ATG or anti-IL2R AI was associated with graft survival in DCD. A secondary endpoint was postoperative renal function as measured by estimated glomerular filtration rate at 6 and 12 months. Among DCD recipients, ATG (hazard ratio [HR] = 0.71; P = 0.03), but not anti-IL2R (HR = 0.82; P = 0.10), was associated with a decrease in graft failure at 3 years when compared with recipients without AI. ATG (HR = 0.90; P = 0.02) and anti-IL2R (HR = 0.94; P = 0.03) were associated with a decreased risk of graft failure in donation after brain death (DBD) liver recipients at 3 years compared with no AI. When induction regimens were compared between DCD and DBD, only ATG (HR = 1.19; P = 0.19), and not anti-IL2R (HR = 1.49; P < 0.01) or no AI (HR = 1.77; P < 0.01), was associated with similar survival between DCD and DBD. In conclusion, AI therapy with ATG was associated with improved longterm liver allograft survival in DCD compared with no AI. ATG was associated with equivalent graft survival between DCD and DBD, suggesting a beneficial role of immune cell depletion in DCD outcomes.

Approach to the liver transplant early postoperative period: an institutional standpoint

The liver transplant program in our center started in 1992, and post-liver transplant patients are still admitted to the intensive care unit. For the intensive care physician, a learning curve started then, skills were acquired, and a specific practice was established. Throughout this time, several concepts changed, improving the care of these patients. The practical approach varies between liver transplant centers, according to local specificities. Hence, we wanted to present our routine practice to stimulate the debate between dedicated teams, which can allow the introduction of new ideas and potentially improve each local standard of care.

Renal Dysfunction After Liver Transplantation: Effect of Donor Type

Recipients of donation after circulatory death (DCD) grafts are reportedly at higher risk of developing renal dysfunction after liver transplantation (LT). We compared the development of acute kidney injury (AKI) and chronic kidney disease (CKD) after LT in recipients of DCD versus donation after brain death (DBD) or living donor liver transplantation (LDLT) livers. Adult recipients of DBD, LDLT, and DCD between 2012 and 2016 at Toronto General Hospital were included. AKI was defined as a post-LT increase of serum creatinine (sCr) ≥26.5 µmol/L within 48 hours or a ≥50% increase from baseline, and CKD was defined as an estimated glomerular filtration rate <60 mL/minute for >3 months. A total of 681 patients (DCD, n = 57; DBD, n = 446; and LDLT, n = 178) with similar baseline comorbidities were included. Perioperative AKI (within the first 7 postoperative days) was observed more frequently in the DCD group (61%; DBD, 40%; and LDLT, 44%; P = 0.01) and was associated with significantly higher peak AST levels (P < 0.001). Additionally, patients in the DCD group had a significantly higher peak sCr (P < 0.001) and a trend toward higher rates of AKI stage 3 (DCD, 33%; DBD, 21%; LDLT, 21%; P = 0.11). The proportions of recovery from AKI (DCD, 77%; DBD, 72%; LDLT, 78%; P = 0.45) and patients developing CKD (DCD, 33%; DBD, 32%; LDLT, 32%; P = 0.99) were similar. Nevertheless, patients who received DCD or DBD LT and required perioperative renal replacement therapy showed significantly lower patient survival in multivariate analysis (hazard ratio, 7.90; 95% confidence interval, 4.51-13.83; P < 0.001). In conclusion, recipients of DCD liver grafts experience higher rates of short-term post-LT renal dysfunction compared with DBD or LDLT. Additional risk factors for the development of severe kidney injury, such as high Model for End-Stage Liver Disease score, massive transfusions, or donor age ≥60 years should be avoided.

Medical management of metabolic and cardiovascular complications after liver transplantation

Liver transplantation represents the only curative option for patients with end-stage liver disease, fulminant hepatitis and advanced hepatocellular carcinoma. Even though major advances in transplantation in the last decades have achieved excellent survival rates in the early post-transplantation period, long-term survival is hampered by the lack of improvement in survival in the late post transplantation period (over 5 years after transplantation). The main etiologies for late mortality are malignancies and cardiovascular complications. The latter are increasingly prevalent in liver transplant recipients due to the development or worsening of metabolic syndrome and all its components (arterial hypertension, dyslipidemia, obesity, renal injury, etc.). These comorbidities result from a combination of pre-liver transplant features, immunosuppressive agent side-effects, changes in metabolism and hemodynamics after liver transplantation and the adoption of a sedentary lifestyle. In this review we describe the most prevalent metabolic and cardiovascular complications present after liver transplantation, as well as proposing management strategies.

Intraoperative Oxygen Delivery and Acute Kidney Injury after Liver Transplantation

Although intraoperative hemodynamic variables were reported to be associated with acute kidney injury (AKI) after liver transplantation, the time-dependent association between intraoperative oxygen delivery and AKI has not yet been evaluated. We reviewed 676 cases of liver transplantation. Oxygen delivery index (DO2I) was calculated at least ten times during surgery. AKI was defined according to the Kidney Disease Improving Global Outcomes criteria. The area under the curve (AUC) was calculated as below a DO2I of 300 (AUC < 300), 400 and 500 mL/min/m2 threshold. Also, the cumulative time below a DO2I of 300 (Time < 300), 400, and 500 mL/min/m2 were calculated. Multivariable logistic regression analysis was performed to evaluate whether AUC < 300 or time < 300 was independently associated with the risk of AKI. As a sensitivity analysis, propensity score matching analysis was performed between the two intraoperative mean DO2I groups using a cutoff of 500 ml/min/m2, and the incidence of AKI was compared between the groups. Multivariable analysis showed that AUC < 300 or time < 300 was an independent predictor of AKI (AUC < 300: odds ratio [OR] = 1.10, 95% confidence interval [CI] 1.06-1.13, time < 300: OR = 1.10, 95% CI 1.08-1.14). Propensity score matching yielded 192 pairs of low and high mean DO2I groups. The incidence of overall and stage 2 or 3 AKI was significantly higher in the lower DO2I group compared to the higher group (overall AKI: lower group, n = 64 (33.3%) vs. higher group, n = 106 (55.2%), P < 0.001). In conclusion, there was a significant time-dependent association between the intraoperative poor oxygen delivery <300 mL/min/m2 and the risk of AKI after liver transplantation. The intraoperative optimization of oxygen delivery may mitigate the risk of AKI.

Fatal diffuse pulmonary fat microemboli following reperfusion in liver transplantation with the use of marginal steatotic allografts

Organ shortage is a major cause of delayed liver transplantation and increased waitlist time. The level of donor steatosis is a significant determinant in organ selection. Scarcity of organs has led some programs to expand their acceptable criteria for the percentage of steatosis. We report two cases of liver transplantation of steatotic donor organs that resulted in mortality within hours from transplantation. Postmortem analysis showed evidence of diffuse pulmonary fat microemboli likely originating from the donor organ, with marked preservation reperfusion injury. The mechanism of diffuse fat microemboli in this setting and possible relationship to other perioperative syndromes (transfusion-related lung injury, acute kidney injury, and postreperfusion syndrome) is discussed.

Urinary and Serum Biomarkers for Prediction of Acute Kidney Injury in Patients Undergoing Liver Transplantation

Acute kidney injury (AKI) is a frequent and serious complication of orthotopic liver transplantation (OLT), with a significant impact on mortality, graft survival, and chronic kidney disease. Currently, the diagnosis of AKI is based on changes in serum creatinine, which is a late marker, usually rising when there is already significant damage to the renal parenchyma. During the last 2 decades, various biomarkers have been studied in many clinical situations, mostly after cardiac surgery, in drug-induced AKI, or in sepsis. The present article summarizes the data on those biomarkers that have been evaluated for the prediction of AKI in patients undergoing OLT.

Liver Grafts From Donors After Circulatory Death on Regional Perfusion With Extended Warm Ischemia Compared With Donors After Brain Death

Donation after circulatory death (DCD) in Italy constitutes a relatively unique population because of the requirement of a no-touch period of 20 minutes. The first aim of this study was to compare liver transplantations from donors who were maintained on normothermic regional perfusion after circulatory death and suffered extended warm ischemia (DCD group, n = 20) with those from donors who were maintained on extracorporeal membrane oxygenation (ECMO) and succumbed to brain death (ECMO group, n = 17) and those from standard donors after brain death (donation after brain death [DBD] group, n = 52). Second, we conducted an explorative analysis on the DCD group to identify relationships between the donor characteristics and the transplant outcomes. The 1-year patient survival for the DCD group (95%) was not significantly different from that of the ECMO group (87%; P = 0.47) or the DBD group (94%; P = 0.94). Graft survival was slightly inferior in the DCD group (85%) because of a high rate of primary nonfunction (10%) and retransplantation (15%) but was not significantly different from the ECMO group (87%; P = 0.76) or the DBD group (91%; P = 0.20). Although ischemic cholangiopathy was more frequent in the DCD group (10%), this issue did not adversely impact graft survival because none of the recipients underwent retransplantation due to biliary complications. Moreover, the DCD recipients were more likely to develop posttransplant renal dysfunction with the need for renal replacement therapy. Further analysis of the DCD group showed that warm ischemia >125 minutes and an Ishak fibrosis score of 1 at liver biopsy negatively impacted serum creatinine and alanine transaminase levels in the first posttransplant week, respectively. In conclusion, our findings encourage the use of liver grafts from DCD donors maintained by regional perfusion after proper selection.

Renal effects of norepinephrine-induced variations in mean arterial pressure after liver transplantation: A randomized cross-over trial

BACKGROUND

Acute kidney injury is commonly seen after liver transplantation. The optimal perioperative target mean arterial pressure (MAP) for renal filtration, perfusion and oxygenation in liver recipients is not known. The effects of norepinephrine-induced changes in MAP on renal blood flow (RBF), oxygen delivery (RDO₂ ), glomerular filtration rate (GFR) and renal oxygenation (=renal oxygen extraction, RO₂ Ex) were therefore studied early after liver transplantation.

METHODS

Ten patients with an intra- and post-operative vasopressor-dependent systemic vasodilation were studied early after liver transplantation during sedation and mechanical ventilation. To achieve target MAP levels of 60, 75 and 90 mm Hg, the norepinephrine infusion rate was randomly and sequentially titrated. At each target MAP, data on cardiac index (CI), RBF and GFR were obtained by transpulmonary thermodilution (PiCCO), the renal vein thermodilution technique and renal extraction of chromium ethylenediaminetetraaceticacid (⁵¹ Cr-EDTA), respectively. Renal oxygen consumption (RVO₂ ) and extraction (RO₂ Ex) were calculated according to standard formulas.

RESULTS

At a target MAP of 75 mm Hg, CI (13%), RBF (18%), RDO₂ (24%), GFR (31%) and RVO₂ (20%) were higher while RO₂ Ex was unchanged compared to a target MAP of 60 mm Hg. Increasing MAP from 75 up to 90 mm Hg increased RVR by 38% but had no further effects on CI, RBF, RDO₂ or GFR.

CONCLUSIONS

In patients undergoing liver transplantation, RBF and GFR are pressure-dependent at MAP levels below 75 mm Hg. Our results suggest that MAP should probably be targeted to approximately 75 mm Hg for optimal perioperative renal filtration, perfusion and oxygenation in patients undergoing liver transplantation.

Neutrophil Gelatinase-Associated Lipocalin (NGAL) in predicting acute kidney injury following orthotopic liver transplantation: A systematic review

BACKGROUND

Acute kidney injury (AKI) is common after orthotopic liver transplantation (OLT) usually occurring early post-transplant. Multiple causes include graft preservation injury, blood loss, hypotension but also severity of recipient liver disease. Early intervention in AKI has both short and long term patient benefits. Unfortunately there are no current clinical biomarkers of early AKI.

AIM

To assess the value of NGAL in predicting AKI following OLT.

METHODS

Ovid MEDLINE and EMBASE were searched between the years of 2000 and 2017 for studies using keywords: Neutrophil Gelatinase Associated Lipocalin or NGAL variants combined with synonyms for liver transplantation.

RESULTS

96 studies were identified. 11 studies including 563 patients were considered suitable for analysis. Both urinary (uNGAL) and plasma NGAL (pNGAL) measurement were found to predict AKI after liver transplantation. Optimal reported area under the receiver-operator characteristics curve (AUROC) values of 0.5-0.83 and 0.54-0.86 respectively.

CONCLUSIONS

NGAL is a good predictor of early AKI post OLT although there is considerable variation in the published results. Further studies with prospectively defined cut-off values, standardized definitions of AKI and rigorous data reporting should be conducted to establish its clinical usefulness and limitations.

Molecular profiling of postreperfusion milieu determines acute kidney injury after liver transplantation: A prospective study

Acute kidney injury (AKI) after liver transplantation (LT) is a common event, but its pathogenesis remains unclear. The aim of this prospective study is to investigate the potential relationship between postreperfusion gene expression, serum mediators, and the onset of AKI after LT. Sixty-five consecutive patients undergoing LT were included in the study. Reverse transcription polymerase chain reaction (PCR) was performed on liver biopsies. Gene expression of 23 genes involved in ischemia/reperfusion injury (IRI) was evaluated. The serum concentrations of endothelin (ET)-1 and inflammatory cytokines were analyzed. AKI after LT developed in 21 (32%) recipients (AKI group). Reverse transcription PCR of reperfusion biopsy in the AKI group showed higher expression of several genes involved in IRI compared with the non-AKI group. Fold changes in the gene expression of ET-1, interleukin (IL) 18, and tumor necrosis factor α (TNF-α) were associated with creatinine peak value. AKI patients also had significantly higher ET-1, IL18, and TNF-α postoperative serum levels. Multivariate analysis showed that ET-1 (odds ratio [OR], 16.7; 95% confidence interval [CI], 3.34-83.42; P = 0.001) and IL18 (OR, 5.27; 95% CI, 0.99-27.82, P = 0.048) serum levels on postoperative day 1 were independently predictive of AKI. Receiver operating characteristic analysis demonstrated that the combination of biomarkers ET-1+IL18 was highly predictive of AKI (area under the receiver operating characteristic curve, 0.91; 95% CI, 0.83-0.99). Early allograft dysfunction and chronic kidney disease stage ≥ 2 occurred more frequently in AKI patients. These results suggest that the graft itself, rather than intraoperative hemodynamic instability, plays a main role in AKI after LT. These data may have mechanistic and diagnostic implications for AKI after LT. Liver Transplantation 24 922-931 2018 AASLD.

Preliminary Experience With Hypothermic Oxygenated Machine Perfusion in an Italian Liver Transplant Center

BACKGROUND

Machine perfusion is increasingly utilized in liver transplantation to face the detrimental consequences of the use of extended-criteria donors. Hypothermic oxygenated machine perfusion (HOPE) appears to be more protective relative to static cold storage. Conversely, normothermic machine perfusion (NMP) allows a better graft evaluation. We describe a pilot prospective study on machine perfusion in selected grafts.

METHODS

HOPE was executed for all the grafts procured from donors after cardiac death (DCDs) and for livers from donors after brain death (DBDs) requiring prolonged preservation time. NMP was used when a more precise evaluation was needed. Both HOPE and NMP were performed through the portal vein and hepatic artery.

RESULTS

From July 2016 to November 2017, we performed 7 HOPE procedures: 5 for DCD and 2 for DBD grafts. Two livers presented with macrovesicular steatosis >30% (1 DCD and 1 DBD). HOPE lasted 240 minutes (180-320 min) with a total ischemia time of 575 minutes (410-810 min). Six grafts were successfully transplanted. One DCD graft required additional evaluation using NMP. The graft was then discarded due to extensive hepatocellular necrosis. In the post-transplant course, acute and chronic renal failure were the main complications affecting 3 and 2 recipients, respectively. In our series, steatosis was the main risk factor for kidney injury. Patient and graft survival rate was 100% and no ischemic cholangiopathies were observed after 270 days (106-582 days).

CONCLUSIONS

Our study confirms HOPE safety and efficacy for DCD and DBD grafts. These data are particularly significant for DCD management in the Italian setting where the mandatory 20-minute hands-off interval before death declaration further prolongs warm ischemia time.

A severely cholestatic liver graft can be successfully used in deceased donor liver transplantation

The shortage of deceased organs is still a serious issue in Japan. A proactive approach to using liver grafts from extended criteria donors (ECDs) may be one way of expanding the donor pool; however, if it is recklessly attempted, a recipient receiving such a marginal graft can be at risk of mortality due to primary non-function or delayed graft function. We herein report the successful outcome of a recipient receiving a severely cholestatic graft that was considered transplantable because it lacked features characteristic of a long duration of "cholestasis" according to the precise interpretation of a donor biopsy. Plasma exchange was intentionally introduced to prevent toxic insult by hyperbilirubinemia immediately after transplant. Despite transient acute kidney injury immediately after transplant, the patient's renal impairment was well managed with a renal-sparing immunosuppressive regimen consisting of basiliximab and mycophenolate mofetil. Although the use of liver grafts from ECDs still needs to be discussed, especially regarding graft selection and allocation policies, efforts not to discard valuable grafts should be undertaken in our country.

Delayed introduction of immunosuppressive regimens in critically ill patients after liver transplantation

BACKGROUND

The manipulation of immunosuppression therapy remains challenging in patients who develop infectious diseases or multiple organ dysfunction after liver transplantation. We evaluated the outcomes of delayed introduction of immunosuppression in the patients after liver transplantation under immune monitoring with ImmuKnow assay.

METHODS

From March 2009 to February 2014, 225 consecutive liver recipients in our institute were included. The delayed administration of immunosuppressive regimens was attempted in 11 liver recipients with multiple severe comorbidities.

RESULTS

The median duration of non-immunosuppression was 12 days (range 5-58). Due to the infectious complications, the serial ImmuKnow assay showed a significantly low ATP level of 64±35 ng/mL in the early period after transplantation. With the development of comorbidities, the ImmuKnow value significantly increased. However, the acute allograft rejection developed when a continuous distinct elevation of both ATP and glutamyltranspeptidase levels was detected. The average ATP level measured just before the development of acute rejection was 271±115 ng/mL.

CONCLUSIONS

The delayed introduction of immunosuppressive regimens is safe and effective in management of critically ill patients after liver transplantation. The serial ImmuKnow assay could provide a reliable depiction of the dynamics of functional immunity throughout the clinical course of a given patient.

Modification of immunosuppressive therapy as risk factor for complications after liver transplantation

Management of complications post-liver transplantation (LT) includes immunosuppressive manipulations with the aim to reduce the overall burden of immunologic suppression and compensate for renal, cardiovascular, metabolic toxicities, and for the increased oncologic risk. Two approaches can be implemented to reduce immunosuppression-related adverse events: upfront schedules tailored to the pretransplant individual patient's risk profile versus downstream modifications in the event of immunosuppression-related complications. Upfront strategies are supported by evidence originating from prospective randomized trials and consist of triple/quadruple schedules whereby calcineurin inhibitors (CNI)-exposure is reduced with combination of anti-CD25 monoclonal antibodies, antimetabolites and corticosteroids. Quadruple regimens allow for staggering of CNI introduction and higher renal function in the early term, but their superiority in the long term has not yet been established. A more recent upfront schedule contemplates early (4 weeks) introduction of mammalian target of rapamycin inhibitor (mTORi) everolimus and allows for reduction of CNI up to 4 years posttransplantation. Incorporation of mTORi has the potential to prolong time to recurrence for patients with hepatocellular carcinoma. However, as suggested by the available evidence, downstream immunosuppressive manipulations are more frequently adopted in clinical practice. These encompass CNI replacement and immunosuppression withdrawal. Switching CNI to mTORi monotherapy is the option most commonly adopted to relieve renal function and compensate for posttransplant malignancies. Its impact is dependent on interval from transplantation and underlying severity of renal impairment. Introduction of mTORi is associated with longer overall survival for patients with extrahepatic posttransplant malignancies, but results are awaited for recurrences of hepatocellular carcinoma. Immunosuppression withdrawal seems feasible (70%) in very long term survivors (>10 years), but is not associated with reversal of immunosuppression-related complications. Awaiting novel immunosuppressive drug categories, integration of upfront strategies with the aim to reduce CNI-exposure and a low threshold for adjustment in the posttransplant course are both advisable to improve long-term outcomes of LT.