Recipient and perioperative risk factors associated with liver transplant graft outcomes

Population pharmacokinetics and thrombocytopenia risk assessment of linezolid in liver transplant recipients

BACKGROUND

Linezolid is a commonly prescribed antibiotic for multidrug-resistant enterococcal infections in liver transplant recipients (LTRs). However, changes in pharmacokinetics due to fluctuations in liver and renal functions, combined with the increased risk of thrombocytopenia, complicate its clinical use. This study aimed to characterize the exposure-thrombocytopenia risk relationship of linezolid in LTRs, and to identify safe dosing thresholds to promote rational drug use.

METHODS

A retrospective analysis was conducted on adult LTRs treated with linezolid at Zhongshan Hospital between January 2019 and May 2022. A population exposure-safety model was developed and used to establish a thrombocytopenia risk threshold and optimize initial dosing strategies through Monte Carlo simulations. An area under the concentration-time curve (AUC) calculator was developed to facilitate individualized dose adjustments.

RESULTS

Exposure-safety analysis revealed that an AUCss,24h threshold of 291.7 mg/L·h was associated with an increased risk of thrombocytopenia. Monte Carlo simulations showed that current covariate-based initial dosing recommendations were suboptimal, highlighting the necessity of therapeutic drug monitoring (TDM) to improve outcomes in LTRs. The online AUC calculator developed in this study offers a practical tool for clinicians to implement timely dose adjustments (https://optimaldose.shinyapps.io/LinezolidAUC/).

CONCLUSIONS

This study provides the first comprehensive analysis of linezolid exposure and its relationship to thrombocytopenia risk in LTRs. The findings underscore the importance of AUC-guided dosing and TDM in optimizing treatment outcomes.

Analysis of two reperfusion techniques in uterine transplantation in an experimental model

INTRODUCTION

Uterine transplantation was developed for the treatment of absolute uterine factor infertility. As it is a new modality of transplantation, there is still room for technical improvement. A factor that impacts graft survival in organ transplantation is the warm ischemia time. In uterine transplantation specifically, at least two vascular anastomoses are performed on each side of the uterus, and the graft revascularization takes place when the vascular clamps of the arteries and veins are released on both sides simultaneously. For this reason, the warm ischemia time in uterine transplant is expected to be considerably long. The purpose of this study was to compare the sequential technique of uterine graft revascularization, which aims to reduce the warm ischemia time of the procedure, with the simultaneous revascularization technique.

MATERIAL AND METHODS

For the procedure, the uterine auto-transplantation technique was performed using 10 non-pregnant adult ewes weighing about 45 kg, divided into two groups: simultaneous revascularization group (5 animals) and sequential revascularization group (5 animals). To evaluate the groups, we analyzed the procedure and warm ischemia times, graft macroscopy, hemodynamic, laboratory, and histological parameters of the uterus.

RESULTS

The sequential revascularization technique group had similar surgical procedure times, and the warm ischemia time was significantly shorter with medians of 32 min in the sequential group vs 72 min in the simultaneous group (p < 0.008). The graft macroscopy and hemodynamic, laboratory, and histological parameters evaluated were similar between the groups.

CONCLUSIONS

The sequential revascularization technique proved to reduce the warm ischemia time in the sheep uterine auto-transplantation model without compromising graft viability.

Primary Nonfunction of the Liver Allograft

Severe allograft dysfunction, as opposed to the expected immediate function, following liver transplantation is a major complication, and the clinical manifestations of such that lead to either immediate retransplant or death are the catastrophic end of the spectrum. Primary nonfunction (PNF) has declined in incidence over the years, yet the impact on patient and healthcare teams, and the burden on the organ pool in case of the need for retransplant should not be underestimated. There is no universal test to define the diagnosis of PNF, and current criteria are based on various biochemical parameters surrogate of liver function; moreover, a disparity remains within different healthcare systems on selecting candidates eligible for urgent retransplantation. The impact on PNF from traditionally accepted risk factors has changed somewhat, mainly driven by the rising demand for organs, combined with the concerted approach by clinicians on the in-depth understanding of PNF, optimal graft recipient selection, mitigation of the clinical environment in which a marginal graft is reperfused, and postoperative management. Regardless of the mode, available data suggest machine perfusion strategies help reduce the incidence further but do not completely avert the risk of PNF. The mainstay of management relies on identifying severe allograft dysfunction at a very early stage and aggressive management, while excluding other identifiable causes that mimic severe organ dysfunction. This approach may help salvage some grafts by preventing total graft failure and also maintaining a patient in an optimal physiological state if retransplantation is considered the ultimate patient salvage strategy.

Intraoperative Factors Associated With Early Recipient Death After Adult-to-Adult Living Donor Liver Transplant

OBJECTIVES

Living donor liver transplant is the gold standard therapy for patients with terminal hepatic disorders for whom no alternative therapy is available. The primary aim was to assess different intraoperative factors that may predict early death after adult-to-adult living donor liver transplant. The secondary aim was to assess the effect of small-for-size syndrome on mortality.

MATERIALS AND METHODS

This retrospective multicenter cohort study was performed on records from 145 adults with cirrhosis who had received a right lobe living donor liver transplant. Patients were divided according to the occurrence of short-term mortality (death within the first month after transplant). The primary intraoperative parameters included graft weight, surgical duration, mean blood pressure, serum lactate and sodium bicarbonate, transfusions, durations of cold and warm ischemia and anhepatic phase, input and output during surgery, and portal venous pressures.

RESULTS

There were statistically significant variations between both cohorts for number of units of packed red blood cells, durations of cold and warm ischemia and anhepatic phase, preclamp and postreperfusion portal venous pressures, average urine output, mean serum lactate, mean blood pressure, and surgical duration (P ⟨ .001). Also, there were significant differences in the number of platelets, units of fresh frozen plasma, and mean sodium bicarbonate (P = .025, .003, and .035, respectively). Of the 25 patients who died within the early postoperative period, 20 had developed small-for-size syndrome (P ⟨ .001).

CONCLUSIONS

A variety of intraoperative risk factors may affect early posttransplant mortality, which suggests the high complexity of living donor liver transplants and the need for well-trained experienced teams to perform these surgeries.

Intraoperative Cardiac Arrest During Adult Liver Transplantation: Incidence and Risk Factor Analysis From 7 Academic Centers in the United States

BACKGROUND

Intraoperative cardiac arrest (ICA) has a reported frequency of 1 in 10,000 anesthetics but has a much higher estimated incidence in orthotopic liver transplantation (OLT). Single-center studies of ICA in OLT are limited by small sample size that prohibits multivariable regression analysis of risks.

METHODS

Utilizing data from 7 academic medical centers, we performed a retrospective, observational study of 5296 adult liver transplant recipients (18-80 years old) between 2000 and 2017 to identify the rate of ICA, associated risk factors, and outcomes.

RESULTS

ICA occurred in 196 cases (3.7% 95% confidence interval [CI], 3.2-4.2) and mortality occurred in 62 patients (1.2%). The intraoperative mortality rate was 31.6% in patients who experienced ICA. In a multivariable generalized linear mixed model, ICA was associated with body mass index (BMI) <20 (odds ratio [OR]: 2.04, 95% CI, 1.05-3.98; P = .0386), BMI ≥40 (2.16 [1.12-4.19]; P = .022), Model for End-Stage Liver Disease (MELD) score: (MELD 30-39: 1.75 [1.09-2.79], P = .02; MELD ≥40: 2.73 [1.53-4.85], P = .001), postreperfusion syndrome (PRS) (3.83 [2.75-5.34], P < .001), living donors (2.13 [1.16-3.89], P = .014), and reoperation (1.87 [1.13-3.11], P = .015). Overall 30-day and 1-year mortality were 4.18% and 11.0%, respectively. After ICA, 30-day and 1-year mortality were 43.9% and 52%, respectively, compared to 2.6% and 9.3% without ICA.

CONCLUSIONS

We established a 3.7% incidence of ICA and a 1.2% incidence of intraoperative mortality in liver transplantation and confirmed previously identified risk factors for ICA including BMI, MELD score, PRS, and reoperation and identified new risk factors including living donor and length of surgery in this multicenter retrospective cohort. ICA, while rare, is associated with high intraoperative mortality, and future research must focus on therapy to reduce the incidence of ICA.

Novel Technique in a Sheep Model of Uterine Transplantation

INTRODUCTION

Uterine transplantation (UTx) is a surgical therapeutic modality designed for the treatment of patients with exclusive uterine factor infertility. Experimental models are paramount to study this transplant modality, and as the ewes' uteri are very similar to that of humans, they are frequently used with this purpose. The aim of this study is to describe a novel technical variation for UTx in sheep.

METHODS

This study was conducted at Laboratory of Medical Investigation 37 of the University of São Paulo School of Medicine in São Paulo, Brazil, and was approved by the Ethics Committee of Animal Use of the university. We used 3 adult female sheep that weighed approximately 45 kg and were not pregnant. We performed the technique of uterine autotransplantation with a novel technical variation that we called sequential vascularization: first, we performed the right uterine artery and vein anastomoses, after which the uterine graft was vascularized, and then the contralateral vascular anastomoses were performed.

CONCLUSION

We described 3 successful uterine autotransplants in sheep models with sequential vascularization. This variation technique will probably allow warm ischemia time in UTx to significantly decrease.

Risk factors, surgical complications and graft survival in liver transplant recipients with early allograft dysfunction

BACKGROUND

Early allograft dysfunction (EAD) is a severe complication after liver transplantation. The associated risk factors and complications have re-gained recent interest. This study investigated risk factors, survival and complications associated with EAD in a large liver transplant center in Latin America.

METHODS

Retrospective, unicenter, cohort, based on data from adult patients undergoing first deceased-donor liver transplant from January 2009 to December 2013. EAD was defined by one or more of the following: (i) bilirubin ≥10 mg/dL on postoperative day 7; (ii) international normalized ratio ≥1.6 on postoperative day 7, and (iii) alanine aminotransferase or aspartate aminotransferase >2000 IU/L within the first seven days after transplant.

RESULTS

A total of 602 patients were included; of these 34.2% developed EAD. Donor risk factors were male (P = 0.007), age between 50 and 59 years (P = 0.034), overweight (P = 0.028) or grade I obesity (P = 0.012), sodium >157 mmol/L (P = 0.002) and grade IV ischemia/reperfusion injury (P = 0.002). Cold ischemia time ≥10 h (P = 0.008) and warm ischemia time ≥40 min (P = 0.013) were the surgical factors. Male (P <0.001) was the only recipient protective factor. Compared with the non-EAD group, patients with EAD were submitted to more reoperations (24.3% vs. 13.4%, P = 0.001) and had higher graft loss rates (37.9% vs. 21.2%, P <0.001), with similar patient survival rates (P = 0.238).

CONCLUSIONS

EAD risk factors are related to donor, surgical procedure and recipient. Donor risk factors for EAD were male, age between 50 and 59 years, donor overweight or grade I obesity, sodium >157 mmol/L and grade IV ischemia/reperfusion injury. Cold ischemia time ≥10 h and warm ischemia time ≥40 min were the surgical risk factors. Male was the only recipient protective factor. Patients with EAD had higher reoperations and graft loss rates.

Indocyanine green fluorescence imaging to evaluate graft perfusion during liver transplantation

BACKGROUND

Primary graft dysfunction (PGD) is a leading cause of graft loss after liver transplantation. There is no reliable method to anticipate this complication intraoperatively. Indocyanine green (ICG) fluorescence imaging is a technique used in hepatobiliary surgery for detection of liver malignancies, but has never been reported in the setting of liver transplantation (LT) for function assessment. We hypothesized that there could be an association between the type of fluorescence and the occurrence of PGD.

METHODS

We retrospectively analyzed 72 patients who underwent LT at our center. An assessment of the liver graft with the ICG fluorescence technique was carried out. A classification comprising 3 types of fluorescence was created after evaluation of the recorded images. We assessed the relationship between the type of fluorescence and the occurrence of PGD.

RESULTS

Crosstabulation analysis of the fluorescent types and occurrence of PGD yielded a statistically significant association (p = 0.002). Univariate analysis showed that an abnormal ICG fluorescence pattern was a risk factor for the occurrence of PGD after LT.

CONCLUSIONS

Our findings suggest that there could be an association between ICG fluorescence imaging and graft function. This intraoperative tool could be useful to detect patients at risk of developing PGD after LT.

Primary graft dysfunction of the liver: definitions, diagnostic criteria and risk factors

Primary graft dysfunction is a multifactorial syndrome with great impact on liver transplantation outcomes. This review article was based on studies published between January 1980 and June 2015 and retrieved from PubMed database using the following search terms: "primary graft dysfunction", "early allograft dysfunction", "primary non-function" and "liver transplantation". Graft dysfunction describes different grades of graft ischemia-reperfusion injury and can manifest as early allograft dysfunction or primary graft non-function, its most severe form. Donor-, surgery- and recipient-related factors have been associated with this syndrome. Primary graft dysfunction definition, diagnostic criteria and risk factors differ between studies. RESUMO A disfunção primária do enxerto hepático é uma síndrome multifatorial com grande impacto no resultado do transplante de fígado. Foi realizada uma ampla revisão da literatura, consultando a base de dados PubMed, em busca de estudos publicados entre janeiro de 1980 e junho de 2015. Os termos descritivos utilizados foram: "primary graft dysfunction", "early allograft dysfunction", "primary non-function" e "liver transplantation". A disfunção traduz graus diferentes da lesão de isquemia e reperfusão do órgão, e pode se manifestar como disfunção precoce ou, na forma mais grave, pelo não funcionamento primário do enxerto. Fatores relacionados ao doador, ao transplante e ao receptor contribuem para essa síndrome. Existem definições diferentes na literatura quanto ao diagnóstico e aos fatores de risco associados à disfunção primária.

CT Features of Primary Graft Nonfunction after Liver Transplantation

Purpose To determine computed tomographic (CT) features of primary graft nonfunction (PNF) after liver transplantation in comparison with those of early graft failure or death by identifiable causes. Materials and Methods Institutional review board approval was obtained and informed consent was waived. Among 3947 adult liver transplantations performed in one institution between May 2002 and May 2015, 72 patients died or had graft failure within 10 days, and 38 of them were evaluated with CT. PNF was diagnosed in 21 patients. The other 17 patients who died or had early graft failure were considered the non-PNF control group. On unenhanced CT images, graft attenuation was compared qualitatively. Graft attenuation was measured quantitatively and, if available, the difference between preoperative and postoperative CT (interval change) attenuation was evaluated. Unenhanced CT was evaluated for relative parenchymal enhancement. Statistical analyses included the Fisher exact and χ² tests with Yates correction and the Student t test. Results On unenhanced CT images, grafts with PNF more commonly showed low (eight of 26 [31%]) or extremely low (18 of 26 [69%]) qualitative attenuation compared with grafts in the non-PNF group (three of 21 [14%], one of 21 [5%]; P < .001). The mean attenuation value (30.5 HU ± 10.8) was significantly lower and the mean interval change (24.7 HU ± 12.5) was significantly higher in the PNF group than in the non-PNF group (49.7 HU ± 8.0 and 9.7 HU ± 10.1, respectively; P < .001 and P = .001). There was no significant difference in the proportion of grafts that showed poor enhancement on postcontrast CT images between the PNF group and the non-PNF group (nine of 24 [38%] vs two of 20 [10%], respectively; P = .08). Conclusion Recipients with PNF after liver transplantation tended to show low or extremely low attenuation on unenhanced CT images, and this finding was seen more frequently in patients with PNF than in those who died of identifiable causes and in those with early graft failure. ^© RSNA, 2016 Online supplemental material is available for this article.

Predictive factors of short term outcome after liver transplantation: A review

Liver transplantation represents a fundamental therapeutic solution to end-stage liver disease. The need for liver allografts has extended the set of criteria for organ acceptability, increasing the risk of adverse outcomes. Little is known about the early postoperative parameters that can be used as valid predictive indices for early graft function, retransplantation or surgical reintervention, secondary complications, long intensive care unit stay or death. In this review, we present state-of-the-art knowledge regarding the early post-transplantation tests and scores that can be applied during the first postoperative week to predict liver allograft function and patient outcome, thereby guiding the therapeutic and surgical decisions of the medical staff. Post-transplant clinical and biochemical assessment of patients through laboratory tests (platelet count, transaminase and bilirubin levels, INR, factor V, lactates, and Insulin Growth Factor 1) and scores (model for end-stage liver disease, acute physiology and chronic health evaluation, sequential organ failure assessment and model of early allograft function) have been reported to have good performance, but they only allow late evaluation of patient status and graft function, requiring days to be quantified. The indocyanine green plasma disappearance rate has long been used as a liver function assessment technique and has produced interesting, although not univocal, results when performed between the 1(th) and the 5(th) day after transplantation. The liver maximal function capacity test is a promising method of metabolic liver activity assessment, but its use is limited by economic cost and extrahepatic factors. To date, a consensual definition of early allograft dysfunction and the integration and validation of the above-mentioned techniques, through the development of numerically consistent multicentric prospective randomised trials, are necessary. The medical and surgical management of transplanted patients could be greatly improved by using clinically reliable tools to predict early graft function.

Incidence and Outcomes of Acute Renal Failure Following Liver Transplantation: A Population-Based Cohort Study

The aim of our large, population-based, cohort study was to explore the risk factors of acute renal failure (ARF) after liver transplant (LT) in Taiwan.From the Taiwanese National Health Insurance Research Database, 2862 patients who had undergone LT without pretransplant dialysis between July 1, 1998, and December 31, 2012, were identified. Preoperative, operative, and perioperative risks factors were considered and analyzed using logistic regression analysis, after adjusting for age and sex. All patients were followed up until the study endpoint or death.The final dataset included 214 patients with ARF and 2648 without ARF post-LT. Preoperative cerebrovascular diseases were the most important identifiable risk factor for ARF post-LT. Comparison of outcomes for patients "with" and "without" ARF indicated higher incidence rates of bacteremia, pneumonia, and postoperative bleeding, as well as longer stays in both intensive care unit and hospital. Kaplan-Meier mortality curves identified higher rates of mortality for patients' developing ARF at 1-year post-LT and overall at 14.5 years postsurgery.We provide evidence of a high incidence of ARF post-LT in Taiwan, with documented association of ARF with higher incidence rates of morbidity and mortality in this clinical population. The most important identifiable risk factor for ARF in our study was cerebrovascular diseases.

Primary graft dysfunction after liver transplantation

BACKGROUND

Primary graft dysfunction (PGD) causes complications in liver transplantation, which result in poor prognosis. Recipients who develop PGD usually experience a longer intensive care unit and hospital stay and have higher mortality and graft loss rates compared with those without graft dysfunction. However, because of the lack of universally accepted definition, early diagnosis of graft dysfunction is difficult. Additionally, numerous factors affect the allograft function after transplantation, making the prediction of PGD more difficult. The present review was to analyze the literature available on PGD and to propose a definition.

DATA SOURCE

A search of PubMed (up to the end of 2012) for English-language articles relevant to PGD was performed to clarify the characteristics, risk factors, and possible treatments or interventions for PGD.

RESULTS

There is no pathological diagnostic standard; many documented definitions of PGD are different. Many factors, such as donor status, procurement and transplant process and recipient illness may affect the function of graft, and ischemia-reperfusion injury is considered the direct cause. Potential managements which are helpful to improve graft function were investigated. Some of them are promising.

CONCLUSIONS

Our analyses suggested that the definition of PGD should include one or more of the following variables: (1) bilirubin ≥ 10 mg/dL on postoperative day 7; (2) international normalized ratio ≥ 1.6 on postoperative day 7; and (3) alanine aminotransferase or aspartate aminotransferase >2000 IU/L within 7 postoperative days. Reducing risk factors may decrease the incidence of PGD. A majority of the recipients could recover from PGD; however, when the graft progresses into primary non-function, the patients need to be treated with re-transplantation.