Factors during donor care that may affect liver transplantation outcome

Brazilian guidelines for the management of brain-dead potential organ donors. The task force of the AMIB, ABTO, BRICNet, and the General Coordination of the National Transplant System

OBJECTIVE

To contribute to updating the recommendations for brain-dead potential organ donor management.

METHOD

A group of 27 experts, including intensivists, transplant coordinators, transplant surgeons, and epidemiologists, joined a task force formed by the General Coordination Office of the National Transplant System/Brazilian Ministry of Health (CGSNT-MS), the Brazilian Association of Intensive Care Medicine (AMIB), the Brazilian Association of Organ Transplantation (ABTO), and the Brazilian Research in Intensive Care Network (BRICNet). The questions were developed within the scope of the 2011 Brazilian Guidelines for Management of Adult Potential Multiple-Organ Deceased Donors. The topics were divided into mechanical ventilation, hemodynamic support, endocrine-metabolic management, infection, body temperature, blood transfusion, and use of checklists. The outcomes considered for decision-making were cardiac arrest, number of organs recovered or transplanted per donor, and graft function/survival. Rapid systematic reviews were conducted, and the quality of evidence of the recommendations was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. Two expert panels were held in November 2016 and February 2017 to classify the recommendations. A systematic review update was performed in June 2020, and the recommendations were reviewed through a Delphi process with the panelists between June and July 2020.

RESULTS

A total of 19 recommendations were drawn from the expert panel. Of these, 7 were classified as strong (lung-protective ventilation strategy, vasopressors and combining arginine vasopressin to control blood pressure, antidiuretic hormones to control polyuria, serum potassium and magnesium control, and antibiotic use), 11 as weak (alveolar recruitment maneuvers, low-dose dopamine, low-dose corticosteroids, thyroid hormones, glycemic and serum sodium control, nutritional support, body temperature control or hypothermia, red blood cell transfusion, and goal-directed protocols), and 1 was considered a good clinical practice (volemic expansion).

CONCLUSION

Despite the agreement among panel members on most recommendations, the grade of recommendation was mostly weak. The observed lack of robust evidence on the topic highlights the importance of the present guideline to improve the management of brain-dead potential organ donors.

Diabetes Mellitus and Liver Surgery: The Effect of Diabetes on Oxidative Stress and Inflammation

Diabetes mellitus (DM) is a metabolic disorder characterized by hyperglycaemia and high morbidity worldwide. The detrimental effects of hyperglycaemia include an increase in the oxidative stress (OS) response and an enhanced inflammatory response. DM compromises the ability of the liver to regenerate and is particularly associated with poor prognosis after ischaemia-reperfusion (I/R) injury. Considering the growing need for knowledge of the impact of DM on the liver following a surgical procedure, this review aims to present recent publications addressing the effects of DM (hyperglycaemia) on OS and the inflammatory process, which play an essential role in I/R injury and impaired hepatic regeneration after liver surgery.

Extended criteria donors in liver transplantation Part I: reviewing the impact of determining factors

The definition and factors of extended criteria donors have already been set; however, details of the various opinions still differ in many respects. In this review, we summarize the impact of these factors and their clinical relevance. Elderly livers must not be allocated for hepatitis C virus (HCV) positives, or patients with acute liver failure. In cases of markedly increased serum transaminases, donor hemodynamics is an essential consideration. A prolonged hypotension of the donor does not always lead to an increase in post-transplantation graft loss if post-OLT care is proper. Hypernatremia of less than 160 mEq/L is not an absolute contraindication to accept a liver graft per se. The presence of steatosis is an independent and determinant risk factor for the outcome. The gold standard of the diagnosis is the biopsy. This is recommended in all doubtful cases. The use of HCV+ grafts for HCV+ recipients is comparable in outcome. The leading risk factor for HCV recurrence is the actual RNA positivity of the donor. The presence of a proper anti-HBs level seems to protect from de novo HBV infection. A favourable outcome can be expected if a donation after cardiac death liver is transplanted in a favourable condition, meaning, a warm ischemia time < 30 minutes, cold ischemia time < 8-10 hours, and donor age 50-60 years. The pathway of organ quality assessment is to obtain the most relevant information (e.g. biopsy), consider the co-existing donor risk factors and the reserve capacity of the recipient, and avoid further technical issues.

Impact of deceased organ donor demographics and critical care end points on liver transplantation and graft survival rates

BACKGROUND

The criteria for organ acceptance remain inconsistent, which limits the ability to standardize critical care practices. We sought to examine predictors of liver graft use and survival to better guide the selection and management of potential organ donors.

STUDY DESIGN

A prospective observational study of all donors managed by the 8 organ procurement organizations in United Network for Organ Sharing Region 5 was conducted from July 2008 to March 2011. Critical care end points that reflect the normal hemodynamic, acid-base, respiratory, endocrine, and renal status of the donor were collected at 3 time points. Critical care and demographic data associated with liver transplantation and graft survival rates were first determined using univariate analyses, and then logistic regression was used to identify independent predictors of these two outcomes.

RESULTS

From 961 donors, 730 (76%) livers were transplanted and 694 (95%) were functioning after 74 ± 73 days of follow-up. After regression analysis, donor BMI (odds ratio [OR] = 0.94), male sex (OR = 1.89), glucose <150 mg/dL (OR = 1.97), lower dopamine dose (OR = 0.95), vasopressin use (OR = 1.95), and ejection fraction >50% (OR = 1.77) remained as independent predictors of liver use. Graft survival was associated with lower donor BMI (OR = 0.91) and sodium levels (OR = 0.95).

CONCLUSIONS

After controlling for donor age, sex, and BMI, both hemodynamic and endocrine critical care end points were associated with increased liver graft use. Both donor BMI and lower sodium levels during the course of donor management were independently predictive of improved graft survival. These results may help guide the management and selection of potential organ donors after neurologic determination of death.

The protective effect of diosmin on hepatic ischemia reperfusion injury: an experimental study

Liver ischemia reperfusion injury (IRI) is an important pathologic process leading to bodily systemic effects and liver injury. Our study aimed to investigate the protective effects of diosmin, a phlebotrophic drug with antioxidant and anti-inflammatory effects, in a liver IRI model. Forty rats were divided into 4 groups. Sham group, control group (ischemia-reperfusion), intraoperative treatment group, and preoperative treatment group. Ischemia reperfusion model was formed by clamping hepatic pedicle for a 60 minute of ischemia followed by liver reperfusion for another 90 minutes. Superoxide dismutase (SOD) and catalase (CAT) were measured as antioaxidant enzymes in the liver tissues, and malondialdehyde (MDA) as oxidative stress marker, xanthine oxidase (XO) as an oxidant enzyme and glutathione peroxidase (GSH-Px) as antioaxidant enzyme were measured in the liver tissues and the plasma samples. Hepatic function tests were lower in treatment groups than control group (p<0.001 for ALT and AST). Plasma XO and MDA levels were lower in treatment groups than control group, but plasma GSH-Px levels were higher (p<0.05 for all). Tissue MDA levels were lower in treatment groups than control group, but tissue GSH-Px, SOD, CAT and XO levels were higher (p<0.05 for MDA and p<0.001 for others). Samples in control group histopathologically showed morphologic abnormalities specific to ischemia reperfusion. It has been found that both preoperative and intraoperative diosmin treatment decreases cellular damage and protects cells from toxic effects in liver IRI. As a conclusion, diosmin may be used as a protective agent against IRI in elective and emergent liver surgical operations.

The difficulty in defining extended donor criteria for liver grafts: the Eurotransplant experience

Donor criteria for liver grafts have been expanded because of organ shortage. Currently, no exact definitions for extended donor grafts have been established. The aim of this study was to analyze the impact of donor-specific risk factors, independent of recipient characteristics. In collaboration with Eurotransplant and European Liver Transplant Register, solely donor-specific parameters were correlated with 1-year survival following liver transplantation. Analyses of 4701 donors between 2000 and 2005 resulted in the development of a nomogram to estimate graft survival for available grafts. Predictions by nomogram were compared to those by Donor Risk Index (DRI). In the multivariate analysis, cold ischemic time (CIT), highest sodium, cause of donor death, γ-glutamyl transferase (γ-GT), and donor sex (female) were statistically significant factors for 3 months; CIT, γ-GT, and cause of donor death for 12-month survival. The median DRI of this study population was 1.45 (Q1: 1.17; Q3: 1.67). The agreement between the nomogram and DRI was weak (kappa = 0.23). Several donor-specific risk factors were identified for early survival after liver transplantation. The provided nomogram will support quick organ quality assessment. Nevertheless, this study showed the difficulties of determining an exact definition of extended criteria donors.

Effect of oxidative stress and endotoxin on human serum albumin in brain-dead organ donors

Albumin, among other molecules, binds and detoxifies endotoxin in healthy people. Oxidative stress leads to protein oxidation and thus to the impaired binding properties of albumin. This property, in combination with increased gut permeability, leads to the appearance of endotoxin in the systemic circulation and to impaired organ function. We hypothesize that these processes occur in the serum of brain-dead organ donors. Endotoxin was determined with an adapted Limulus amoebocyte lysate assay. The albumin fractions and binding capacity were determined by high-performance liquid chromatography (HPLC). FlowCytomix (eBioscience, San Diego, Calif) was used to determine the cytokine levels. Carbonylated proteins (CPs) and myeloperoxidase (MPO) were measured by an enzyme-linked immunosorbent assay (ELISA). Eighty-four brain-dead organ donors were enrolled and categorized by the duration of intensive care unit (ICU) stay. The albumin-binding capacity for dansylsarcosine was reduced in brain-dead patients compared with controls. Endotoxin positivity in 16.7% of donors was associated with decreased binding capacity in donors and worse survival of recipients. The CP and MPO levels of organ donors were significantly higher than in healthy controls. The durations of ICU stay increased albumin oxidation. In addition, interleukin-6 (IL-6), IL-8, IL-10, and IL-1β levels were increased in patients, whereas the interferon-γ (IFN-γ) levels were within the normal range. We conclude that oxidative stress and systemic endotoxemia are present in brain-dead organ donors, which might affect recipient survival. High endotoxin levels might be caused by increased gut permeability and decreased binding capacity of albumin influenced not just by higher albumin oxidation.

Ischemic preconditioning-like effect of polyunsaturated fatty acid-rich diet on hepatic ischemia/reperfusion injury

AIM

The aim of this study was to investigate a possible preconditioning effect of oral diet enriched with polyunsaturated fatty acids (PUFAs) on liver ischemia/reperfusion (I/R) injuries.

METHODS

Wistar male rats were fed a standard diet or polyunsaturated fatty acid-rich diet (PRD) enriched with (GII) or without (GIII) ω-3 PUFA. Rats were submitted to partial liver ischemia during 1 h and evaluated in pre- and post-I/R conditions. In pre-I/R condition, livers were collected for determination of fatty acid composition, liver mitochondrial function, malondialdehyde (MDA) content, and histological analysis. Four hours after liver reperfusion serum activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), serum levels of tumor necrosis factor-alpha, interleukin-6, interleukin-10, and prostaglandin-E2, liver mitochondrial function, MDA content, and histology were evaluated.

RESULTS

In the pre-I/R condition, GII and GIII groups had an increase on PUFA content and exhibited slight increased macrosteatosis and microsteatosis in the liver. After 4 h of reperfusion, PRD-fed rats showed a marked decrease on steatosis, diminished necrosis, an increase in MDA formation, and mitochondrial uncoupling. We also observed a marked decrease in plasma levels of cytokines and ALT and AST activities in post-I/R condition in PRD groups.

CONCLUSION

In this experimental model in the rat, PRD has a preconditioning effect protecting the liver from I/R injury and should be object of future clinical studies.

Impact of donor cause of death on transplant outcomes: UNOS registry analysis

Donor cause of death (DCOD) has been described to influence allograft survival. Whether this effect is independent of other donor characteristics and whether it is similar across different solid organ allografts is not known. The aim of our study was to determine the impact of DCOD on organ utilization and on transplantation outcomes-graft rejection, function, and survival. The registry data were provided by the United Network for Organ Sharing/Organ Procurement and Transplantation Network. Stroke, head trauma, and anoxia were the cause of brain death in 97% of the more than 86,000 donors whose data were recorded between 1989 and 2008. In univariate analysis, stroke DCOD was associated with worse graft survival across all organs. After adjustment in a multivariable analysis, modest differences persisted in survival of heart, kidney, and liver allografts. DCOD also appeared to affect the incidence of allograft rejection. Anoxia DCOD was associated with significantly less rejection relative to donor death caused by head trauma and stroke. In summary, this multi-institutional study confirms that DCOD is a modest predictor of survival and rejection of solid organ allografts of different types.

Role of free radicals in liver diseases

Reactive oxygen and nitrogen species (ROS and RNS) are produced by metabolism of normal cells. However, in liver diseases, redox is increased thereby damaging the hepatic tissue; the capability of ethanol to increase both ROS/RNS and peroxidation of lipids, DNA, and proteins was demonstrated in a variety of systems, cells, and species, including humans. ROS/RNS can activate hepatic stellate cells, which are characterized by the enhanced production of extracellular matrix and accelerated proliferation. Cross-talk between parenchymal and nonparenchymal cells is one of the most important events in liver injury and fibrogenesis; ROS play an important role in fibrogenesis throughout increasing platelet-derived growth factor. Most hepatocellular carcinomas occur in cirrhotic livers, and the common mechanism for hepatocarcinogenesis is chronic inflammation associated with severe oxidative stress; other risk factors are dietary aflatoxin B(1) consumption, cigarette smoking, and heavy drinking. Ischemia-reperfusion injury affects directly on hepatocyte viability, particularly during transplantation and hepatic surgery; ischemia activates Kupffer cells which are the main source of ROS during the reperfusion period. The toxic action mechanism of paracetamol is focused on metabolic activation of the drug, depletion of glutathione, and covalent binding of the reactive metabolite N-acetyl-p-benzoquinone imine to cellular proteins as the main cause of hepatic cell death; intracellular steps critical for cell death include mitochondrial dysfunction and, importantly, the formation of ROS and peroxynitrite. Infection with hepatitis C is associated with increased levels of ROS/RNS and decreased antioxidant levels. As a consequence, antioxidants have been proposed as an adjunct therapy for various liver diseases.

Consequences of head injury and static cold storage on hepatic function: ex vivo experiments using a model of isolated perfused rat liver

The purpose of the study was to evaluate the effect of head injury (HI) on the metabolic and energy functions of the liver and its consequences after cold storage. In male SD rats with HI, livers were isolated 4 days after injury and perfused either immediately (HI) or after 24 hours of cold preservation. Livers isolated from healthy rats were treated identically. The hepatic functions were explored with an isolated perfused liver model. Head injury induced a liver atrophy without significant difference in the intrahepatic energy level versus healthy rats. After cold storage, hepatic adenosine triphosphate and glycogen contents in HI rats were similar to those of healthy rats. The livers of the HI group that underwent cold preservation had a lower protein catabolism. The portal flow rate at the time of reperfusion was significantly increased in the HI group. In conclusion, static cold storage of livers harvested from HI rats revealed a net protein catabolism reduction and a modification of hepatic microcirculation.

Association between donor-recipient serum sodium differences and orthotopic liver transplant graft function

Previous studies have shown that donor hypernatremia and possibly recipient hyponatremia negatively impact graft function after orthotopic liver transplant (OLT). The purpose of this retrospective investigation was to determine whether measured differences in serum sodium values between cadaveric donors and OLT recipients (DeltaNa(+)) influence immediate postoperative allograft function and short-term patient outcomes. Two hundred and fifty patients that underwent OLT from January 2001 to December 2005 were included in this study. The DeltaNa(+) for each donor recipient pair was correlated with standard postoperative liver function tests as well as recipient length of intensive care unit stay (LOICUS), length of hospital stay (LOHS) and recipient survival. The relationship between donor hypernatremia (serum sodium >or= 155 mEq/mL), recipient hyponatremia (serum sodium level <or= 130 mEq/mL), and postoperative outcomes were analyzed as well. Adjustments were made for baseline potential confounders, including model for end-stage liver disease (MELD) score, preservation solution used (HTK vs. UW), recipient and donor demographics and cold ischemia time (CIT). DeltaNa(+) as well as donor hypernatremia and recipient hyponatremia were not found to be associated with immediate postoperative allograft function, intraoperative blood product usage, LOICUS, LOHS or short-term patient survival. However, both the preoperative MELD score and HTK preservation solution used were significantly associated with several patient outcomes. A higher MELD score was associated with both increased red blood cell (RBC) (P < 0.001) and fresh frozen plasma (FFP) usage (P = 0.002), elevated postoperative total bilirubin levels (P < 0.001), increased LOHS (P = 0.04), and a higher 30-day post transplant mortality (P = 0.02). The use of HTK preservation solution was associated with higher mean postoperative aspartate aminotransferase levels (P = 0.02) and decreased mean RBC (P < 0.001) and FFP usage (P = 0.009) compared to UW preservation solution use.

Factors in the pathophysiology of the liver ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury is commonplace in liver surgery, particularly in hepatic transplantation, hepatic resection, and trauma. The signaling events contributing to local hepatocellular damage are diverse and complex and involve the interaction between hepatocytes, sinusoidal endothelial cells, Kupffer cells, as well as infiltrating neutrophils, macrophages, and platelets. Signaling mediators include cytokines, reactive oxygen and nitrogen species, calcium, complement, and several transcription factors. The purpose of this review article was to summarize the factors that contribute to the pathophysiology of hepatic ischemia-reperfusion injury.