Risk factors for acute kidney injury following orthotopic liver transplantation: the impact of changes in renal function while patients await transplantation

Intraoperative hypotension and the risk of acute kidney injury following liver transplantation

BACKGROUND

Acute kidney injury (AKI) is a frequent adverse outcome following liver transplantation (LT) with a multifactorial etiology. It is critical to identify modifiable risk factors to mitigate the risk. One key area of interest is the role of intraoperative hypotension, which remains relatively unexplored in liver transplant cohorts.

METHODS

This was a retrospective observational cohort study of 1292 adult patients who underwent LT (between 2009 and 2019). Multivariable logistic regression analysis was used to explore the association between intraoperative hypotension, quantified by time duration (in min) under various mean arterial pressure (MAP) thresholds, and the primary outcome of early postoperative AKI according to the KDIGO criteria.

RESULTS

AKI occurred in 40% of patients and was independently associated with greater than 20 min spent below MAP thresholds of 55 mm Hg (adjusted OR = 1.866; 95% CI = 1.037-3.44; P = 0.041) and 50 mm Hg (adjusted OR = 1.801; 95% CI = 1.087-2.992; P = 0.023). Further sensitivity analyses demonstrated that the association between intraoperative hypotension and postoperative AKI was accentuated after restricting the analysis to patients with a normal preoperative renal function.

CONCLUSIONS

Prolonged (>20 min) intraoperative hypotension (below a MAP of 55 mm Hg) was independently associated with AKI following LT, after adjusting for several known confounders.

[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.

Acute kidney injury after liver transplantation, perioperative risk factors, and outcome: prospective observational study of 1681 patients (OLTx Study)

BACKGROUND

Acute kidney injury (AKI) represents a frequent complication after orthotopic liver transplantation (OLT). This study aimed to evaluate early postoperative AKI incidence during the first 72 h after OLT, perioperative risk factors, and AKI impact on survival.

METHODS

From January 2011 to December 2013) 1681 patients underwent OLT in 19 centers and were enrolled in this prospective cohort study.

RESULTS

According to RIFLE criteria, AKI occurred in 367 patients, 21.8% (R: 5.8%, I: 6.4%, F: 4.8%, L: 4.8%). Based on multivariate analysis, intraoperative risk factors for AKI were: administration of 5-10 RBCs (OR 1.8, 95%CI 1.3-2.7), dopamine use (OR 1.6, 95%CI 1.2-2.3), post-reperfusion syndrome (OR 1.5, 95%CI 1.0-2.3), surgical complications (OR 2.0, 95% CI 1.3-3.0), and cardiological complications (OR 2.2, 95%CI 1.2-4.0). Postoperative risk factors were: norepinephrine (OR 1.4, 95%CI 1.0-2.0), furosemide (OR 4.2, 95% CI 3.0-5.9), more than 10 RBCs transfusion, (OR 3.7, 95%CI 1.4-10.5), platelets administration (OR 1.6, 95% CI 1.1-2.4), fibrinogen administration (OR 3.0, 95%CI, 1.5-6.2), hepatic complications (OR 4.6, 95%CI 2.9-7.5), neurological complications (OR 2.4, 95%CI 1.5-3.7), and infectious complications (OR 2.7, 95%CI 1.8-4.3). NO-AKI patients' 5 years survival rate was higher than AKI patients (68.06, 95% CI 62.7-72.7 and 81.2, 95% CI 78.9-83.3, p< 0.001).

CONCLUSIONS

AKI still remains an important risk factor for morbidity and mortality after OLT. Further researches to develop new strategies aimed at preventing or minimizing post-OLT AKI are needed.

Predictors of acute kidney injury in patients with acute decompensated heart failure in emergency departments in China

Objective

This retrospective multicentre observational study was performed to assess the predictors of acute kidney injury (AKI) in patients with acute decompensated heart failure (ADHF) in emergency departments in China.

Methods

In total, 1743 consecutive patients with ADHF were recruited from August 2017 to January 2018. Clinical characteristics and outcomes were compared between patients with and without AKI. Predictors of AKI occurrence and underdiagnosis were assessed in multivariate regression analyses.

Results

Of the 1743 patients, 593 (34.0%) had AKI. AKI was partly associated with short-term all-cause mortality and cost. Cardiovascular comorbidities such as coronary heart disease, diabetes mellitus, and hypertension remained significant predictors of AKI in the univariate analysis. AKI was significantly more likely to occur in patients with a lower arterial pH, lower albumin concentration, higher creatinine concentration, and higher N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration. Patients treated with inotropic agents were significantly more likely to develop AKI during their hospital stay.

Conclusion

This study suggests that cardiovascular comorbidities, arterial pH, the albumin concentration, the creatinine concentration, the NT-proBNP concentration, and use of inotropic agents are predictors of AKI in patients with ADHF.

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.

Early Acute Kidney Injury Associated with Liver Transplantation: A Retrospective Case-Control Study

Background

A retrospective case-control study was carried out to assess the occurrence of acute kidney injury (AKI) in liver transplantation (LT) recipients and its related risk factors.

Material/Methods

The study enrolled 131 patients undergoing LT from December 2017 to June 2019 at Beijing Tsinghua Chang Gung Hospital, China. AKI and its classification were defined according to KDIGO guidelines. We collected patients’ demographic characteristics and perioperative parameters, and identified independent risk factors of AKI by multivariate logistic regression analysis.

Results

We included 122 patients in analysis. AKI occurred in 52 (42.6%) patients (22.1% stage I, 8.2% stage II, and 12.3% stage III). AKI was notably associated with 12 factors: sex, body mass index (BMI), hepatic etiology, MELD score, ascites, prothrombin time (PT), international normalized ratio of prothrombin time (INR), preoperative total bilirubin (TBIL), operative time, total fluid intake, fresh frozen plasma (FFP), and estimated blood loss (EBL) (P<0.05). The factors independently associated with AKI were BMI (adjusted odds ratio: 0.605, 95% confidence interval: 0.425–0.859; P=0.005) and intraoperative FFP infusion (adjusted odds ratio: 0.998, 95% confidence interval: 0.995–1.000; P=0.047). Compared with the non-AKI group, the AKI group showed higher likelihood of renal replacement therapy (RRT), and longer ICU and hospital stays, higher in-hospital mortality, and higher hospitalization costs (P<0.05).

Conclusions

There is a high risk of AKI in patients undergoing LT. BMI and intraoperative FFP infusion are factors independently correlated with AKI. AKI can result in extended hospital stays and higher hospitalization expenses.

Acute Kidney Injury in Critically Ill Patients After Noncardiac Major Surgery: Early Versus Late Onset

OBJECTIVES

Acute kidney injury is a common complication of major surgery. However, acute kidney injury occurring within the first 48 hours after surgery (early acute kidney injury) and therefore likely related to the surgery itself is possibly different from acute kidney injury occurring after 48 hours (late acute kidney injury). The aim of this study was to describe the epidemiology and identify differences in risk factors and outcomes between early and late acute kidney injury following major surgery.

DESIGN

Retrospective cohort study.

SETTING

Academic Medical Center.

PATIENTS

Patients admitted to ICU following noncardiac major surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We analyzed data from 3,499 patients and defined acute kidney injury according to full Kidney Disease: Improving Global Outcomes criteria and classified as early (48 hr or less) or late (> 48 hr to 7 d) based on time from surgery. Separate multivariable logistic regression models were fit to identify risk factors of early acute kidney injury compared with no acute kidney injury and risk factors of late acute kidney injury compared with no acute kidney injury. Overall 41.7% (1,459/3,499) developed early acute kidney injury versus 14.4% (504/3,499) late acute kidney injury. Most acute kidney injury occurred within 48 hours following surgery and 12 hours was the peak interval. Risk factors for early acute kidney injury included increased age, body mass index, decreased estimated glomerular filtration rate, and anemia, whereas late acute kidney injury cases were closely associated with postoperative factors, like sepsis, mechanical ventilation, positive fluid balance, blood transfusions and exposure to diuretics, vasopressors, and nonsteroidal anti-inflammatory drugs. After adjusting for age, body mass index, estimated glomerular filtration rate, comorbidities, surgery type, both early acute kidney injury (odds ratio [95% CI], 1.84 [1.50-2.27]) and late acute kidney injury (odds ratio [95% CI], 1.42 [1.09-1.85]) were associated with higher 1-year mortality compared with patients without acute kidney injury. We found similar results in a validation cohort of 10,723 patients admitted between 2008 and 2014.

CONCLUSIONS

Most surgery-related acute kidney injury occurred within 48 hours of surgery. Acute kidney injury occurring within the first 48 hours was associated with underlying health, whereas acute kidney injury occurring after 48 hours was related to postoperative complications or drugs. Design of clinical and experimental interventions for acute kidney injury in this population should consider these differences.

The AKI Prediction Score: a new prediction model for acute kidney injury after liver transplantation

BACKGROUND

Acute kidney injury (AKI) is a frequent complication after liver transplantation. Although numerous risk factors for AKI have been identified, their cumulative impact remains unclear. Our aim was therefore to design a new model to predict post-transplant AKI.

METHODS

Risk analysis was performed in patients undergoing liver transplantation in two centres (n = 1230). A model to predict severe AKI was calculated, based on weight of donor and recipient risk factors in a multivariable regression analysis according to the Framingham risk-scheme.

RESULTS

Overall, 34% developed severe AKI, including 18% requiring postoperative renal replacement therapy (RRT). Five factors were identified as strongest predictors: donor and recipient BMI, DCD grafts, FFP requirements, and recipient warm ischemia time, leading to a range of 0-25 score points with an AUC of 0.70. Three risk classes were identified: low, intermediate and high-risk. Severe AKI was less frequently observed if recipients with an intermediate or high-risk were treated with a renal-sparing immunosuppression regimen (29 vs. 45%; p = 0.007).

CONCLUSION

The AKI Prediction Score is a new instrument to identify recipients at risk for severe post-transplant AKI. This score is readily available at end of the transplant procedure, as a tool to timely decide on the use of kidney-sparing immunosuppression and early RRT.

Early acute kidney injury after liver transplantation in patients with normal preoperative renal function

AIM

Acute kidney injury (AKI) commonly occurs in patients after liver transplantation (LT). However, few studies have focused on AKI and its correlation with clinical outcomes under the Kidney Disease Improving Global Outcomes (KDIGO) criteria. This study aimed to identity the incidence, risk factors, and impacts of early AKI on outcomes in LT recipients with normal preoperative renal function, according to the KDIGO criteria.

METHODS

Clinical and laboratory data of 227 patients with normal preoperative renal function who underwent LT from January 2011 to January 2015 were retrospectively analyzed.

RESULTS

During the first week after LT, 106 patients (46.7%) developed AKI based on the KDIGO criteria. A multivariate analysis revealed that BMI of > 25, prolonged inferior vena cava clamping, prolonged cold ischemia time, and post-operative RBC requirements > 10 units were independent risk factors for AKI after LT. The area under the receiver operating characteristic curve for the predictive ability of AKI under these risk factors was 0.748. The occurrence of AKI was associated with longer mechanical ventilation time and post-operative ICU stay, increased post-operative 30-day mortality and decreased long-term patient survival.

CONCLUSIONS

Even in patients with normal preoperative renal function, AKI was a frequent complication in LT recipients and had both negative short- or long-term effects on patient outcomes, also the severity of AKI had a dose-response relationship with worse outcomes. Patients with BMI > 25, prolonged inferior vena cava clamping, prolonged cold ischemia time, or post-operative RBC requirement > 10 units should be pay particular attention, which may assist in achieving better clinical outcomes.

Chronic kidney disease in liver transplantation: Evaluation of kidney function

Chronic kidney disease is one of the main comorbidities affecting liver transplant recipients. Most of those patients have some degree of acute or chronic kidney dysfunction at the time of transplantation, moreover they can also develop de novo chronic kidney disease once transplanted. An important increase in the incidence of chronic kidney disease in the «MELD era» has been observed. This phenomenon has partially been attributed to the weight that kidney function carries for organ allocation. In addition, the generalized use of calcineurin inhibitors has also been a contributing factor. It is of the utmost importance for us to be familiar with the current methods for evaluating kidney function before and after a liver transplantation. The two main biomarkers available today for that purpose are serum creatinine and cystatin C. Several equations have been derived from those biomarkers and have been tested in that context with mixed results, due to their biologic variability and the lack of standardization in their measurement. The gold standard continues to be the direct determination of the glomerular filtration rate through different methods; however, that is only done for research purposes. It is also essential to know the current classification of acute kidney injury and chronic kidney disease in order to make early diagnosis. The present review focuses on the recognition, diagnosis, and classification of chronic kidney disease and acute kidney injury in liver transplantation recipients.

Predictive Value of Serum Creatinine, Blood Urea Nitrogen, Uric Acid, and β2-Microglobulin in the Evaluation of Acute Kidney Injury after Orthotopic Liver Transplantation

Background

As a major complication after orthotopic liver transplantation (OLT), the occurrence of acute kidney injury (AKI) is frequently defined by serum creatinine (Cr); however, the accuracy of commonly used blood urea nitrogen (BUN), uric acid (UA), and β₂-microglobulin (β₂-MG) remains to be explored. This retrospective study compared the accuracy of these parameters for post-OLT AKI evaluation.

Methods

Patients who underwent OLT in three centers between July 2003 and December 2013 were enrolled. The postoperative AKI group was diagnosed by the Kidney Disease Improving Global Outcomes (KDIGO) criteria and classified by stage. Measurement data were analyzed using the t-test or Wilcoxon rank-sum test; enumerated data were analyzed using the Chi-square test or Fisher's exact test. Diagnostic reliability and predictive accuracy were evaluated using receiver operating characteristic (ROC) curve analysis.

Results

This study excluded 976 cases and analyzed 697 patients (578 men and 119 women); the post-OLT AKI incidence was 0.409. Compared with the no-AKI group, the AKI group showed very significant differences in Model for End-stage Liver Disease score (14.74 ± 9.91 vs. 11.07 ± 9.54, Z = 5.404; P < 0.001), hepatic encephalopathy (45 [15.8%] vs. 30 [7.3%], χ² = 12.699; P < 0.001), hemofiltration (28 [9.8%] vs. 0 [0.0%], χ² = 42.171; P < 0.001), and 28-day mortality (23 [8.1%] vs. 9 [2.2%], χ² = 13.323; P <0.001). Moreover, mean values of Cr, BUN, UA, and β₂-MG in the AKI group differed significantly at postoperative days 1, 3, and 7 (all P < 0.001). ROC curve area was 0.847 of Cr for the detection of AKI Stage 1 (sensitivity 80.1%, specificity 75.7%, cutoff value 88.23 μmol/L), 0.916 for Stage 2 (sensitivity 87.6%, specificity 82.6%, cutoff value 99.9 μmol/L), and 0.972 for Stage 3 (sensitivity 94.1%, specificity 88.2%, cutoff value 122.90 μmol/L).

Conclusion

The sensitivity and specificity of serum Cr might be a high-value indicator for the diagnosis and grading of post-OLT AKI.

Fluctuations of Estimated Glomerular Filtration Rate Outside Kidney Disease Improving Global Outcomes Diagnostic Criteria for Acute Kidney Injury in End-Stage Liver Disease Outpatients and Outcome Postliver Transplantation

BACKGROUND

Renal dysfunction in end-stage liver disease (ESLD) results from systemic conditions that affect both liver and kidney with activation of vasoconstrictor systems. In this setting, estimated glomerular filtration rate (eGFR) may undergo variations often outside Kidney Disease Improving Global Outcomes criteria for acute kidney injury (AKI) diagnosis, whose meaning is not clear. The aim of this study was to evaluate eGFR variations in ESLD outpatients listed for liver transplant (liver Tx) and the association with post-Tx outcome.

METHODS

Fifty-one patients with ESLD were retrospectively evaluated from listing to transplant (L-Tx time), intraoperatively (Tx time), and up to 5 years post-Tx time. Variations between the highest and the lowest eGFR occurring in more than 48 hours, not satisfying Kidney Disease Improving Global Outcomes guideline, were considered as fluctuations (eGFR-F). Fluctuations of eGFR greater than 50% were defined as eGFR drops (DeGFR). Early graft dysfunction, AKI within 7 days, chronic kidney disease, and short- and long-term patient survivals were considered as outcomes.

RESULTS

All patients presented eGFR-F, whereas DeGFR were observed in 18 (35.3%) of 51 (DeGFR+ group). These patients presented higher levels of Model for End-stage Liver Disease score, pre-Tx bilirubin and significantly greater incidence of post-Tx AKI stages 2 to 3 compared with patients without drops (DeGFR-). DeGFR was the only independent predictive factor of the occurrence of post-Tx AKI. The occurrence of AKI post-Tx was associated with the development of chronic kidney disease at 3 months and 5 years post-Tx.

CONCLUSIONS

Drops of eGFR are more frequently observed in patients with a worse degree of ESLD and are associated with a worse post-Tx kidney outcome.

Acute kidney injury after liver transplantation: Recent insights and future perspectives

Acute kidney injury (AKI) is a common postoperative complication after liver transplantation (LT). The occurrence of postoperative AKI after LT (Post-LT AKI) is associated with inferior patient and graft outcomes. Post-LT AKI is multifactorial in origin and has been related to the severity of liver disease, pre-LT renal dysfunction, graft quality, perioperative events and toxicity of immunosuppressive therapy. Furthermore it is thought that hepatic ischaemia reperfusion injury might be a driving force in the aetiology of post-LT AKI. Novel biomarkers for AKI are emerging and can be useful for early identification and characterization of AKI. There is a clear need for strategies aimed at preventing or treating post-LT AKI. Several pharmacological and non-pharmacological interventions have been studied, but so far failed to show any benefit in the prevention of post-LT AKI. Further studies are needed to develop and evaluate new interventions aimed at preventing post-LT AKI and improve patient outcomes.

Incidence and outcomes of acute kidney injury in patients with hepatocellular carcinoma after liver transplantation

PURPOSE

To describe the incidence and outcomes linked with acute kidney injury (AKI) after liver transplantation (LT) in hepatocellular carcinoma (HCC) patients.

METHODS

From January 2003 to February 2011, HCC patients undergoing LT were retrospectively enrolled. Patient with a glomerular filtration rate (GFR) <60 mL/min/1.73 m² was excluded. AKI was defined and classified according to the AKIN criteria.

RESULTS

Of the 566 eligible patients, AKI was found in 109 (19.26%) patients (stage I, 66 cases; stage II, 15 cases; and stage III, 28 cases). Risk factors for AKI were the long anhepatic time (OR = 3.59, P = 0.009) and prolonged duration of systolic blood pressure (SBP) < 90 mmHg (OR = 1.07, P < 0.0001). Post-LT AKI was an independent risk factor associated with 30-day mortality (HR = 4.05, P = 0.047). Complete recovery occurred in 84 (77.06%) of all AKI episodes within 1 month after operation, while 25 patients (22.94%) suffered from prolonged AKI. Patients with prolonged AKI had a poorer 1-year survival than those with transient AKI (40 vs 86.90%; P < 0.0001). Patients with severe AKI more often developed prolonged AKI. 13 patients (52%) of the prolonged AKI progressed to chronic kidney disease (CKD) defined as eGFR <60 mL/min/1.73 m² after 1 year post-operation.

CONCLUSIONS

Post-LT AKI is not an uncommon complication. Intra-operative hemodynamic instability is crucial in the development of post-LT AKI and deserves more attention. Most post-LT AKI is transient and reversible, while the prolonged form may predict a decrease survival.

Acute kidney injury following liver transplantation: a systematic review of published predictive models

Acute kidney injury is a frequent postoperative complication amongst liver transplant recipients and is associated with increased morbidity and mortality. This systematic review analysed the existing predictive models, in order to solidify current understanding. Articles were selected for inclusion if they described the primary development of a clinical prediction model (either an algorithm or risk score) to predict AKI post liver transplantation. The database search yielded a total of seven studies describing the primary development of a prediction model or risk score for the development of AKI following liver transplantation. The models span thirteen years of clinical research and highlight a gradual change in the definitions of AKI, emphasising the need to employ standardised definitions for subsequent studies. Collectively, the models identify a diverse range of predictive factors with several common trends. They emphasise the impact of preoperative renal dysfunction, liver disease severity and aetiology, metabolic risk factors as well as intraoperative variables including measures of haemodynamic instability and graft quality. Although several of the models address postoperative parameters, their utility in predictive modelling seems to be of questionable relevance. The common risk factors identified within this systematic review provide a minimum list of variables, which future studies should address. Research in this area would benefit from prospective, multi-site studies with larger cohorts as well as the subsequent internal and external validation of predictive models. Ultimately, the ability to identify patients at high risk of post-transplant AKI may enable early intervention and perhaps prevention.

Evaluation of perioperative predictors of acute kidney injury post orthotopic liver transplantation

Acute kidney injury (AKI) is a common complication following orthotopic liver transplantation. It is associated with increased morbidity and mortality, as well as increased healthcare costs. The aetiology of AKI post liver transplantation is multifactorial and understanding these factors is pivotal in developing risk stratification and prevention strategies. This study aims to investigate the preoperative and intraoperative factors that may be associated with AKI in patients undergoing liver transplantation at the Princess Alexandra Hospital, Brisbane, Queensland. In our study, retrospective data of 97 consecutive orthotopic liver transplantations performed between January 2009 and August 2012 were recorded. Univariate and multivariate analyses were performed to investigate the preoperative and intraoperative risk factors for the development of AKI in this cohort. In the cohort of 97 patients who underwent orthotopic liver transplantation, 24 patients (25%) developed postoperative AKI. Univariate analysis demonstrated that high preoperative body mass index and intraoperative noradrenaline use were both associated with AKI. Multivariate analysis demonstrated that high body mass index, high Model for End-stage Liver Disease score and intraoperative noradrenaline use were associated with AKI. Overall mortaility was 4.1% during the study period and was not significantly different between the two groups. The high incidence of AKI following liver transplantation in this study cohort highlights the importance of this issue. This study has identified several potential pre- and intraoperative risk factors, providing a focus for patient surveillance and future research.

Comparing 10-yr renal outcomes in deceased donor and living donor liver transplants

Few studies have explored whether the type of LT, deceased donor LT (DDLT) or living donor LT (LDLT), impacts long-term renal outcomes. We performed a retrospective analysis of 220 LT recipients at our institution to study their renal outcomes at 10 yr. Exclusion criteria were age ≤ 18 yr, graft survival ≤ 6 months, and multiorgan transplants; 108 DDLTs and 62 LDLTs were eligible. At baseline, DDLTs had a lower eGFR than LDLTs and 10.2% of DDLTs were on dialysis as compared to 0% of LDLTs. At 10 yr, seven DDLT and three LDLT recipients required dialysis or renal transplant (p = 0.75). In recipients with graft survival >6 months, DDLTs had a slower decline in eGFR as compared to LDLTs (p < 0.01). Among LDLTs, the decline in eGFR continued over the entire 10-yr period, whereas among DDLTs, the decline in eGFR slowed significantly after six months (p = 0.01). This difference between the two groups was not seen among patients in the highest quartile of baseline eGFR. Patient survival and graft survival were similar. In conclusion, the incidence of end-stage renal disease was similar in both DDLT and LDLT patients, but LDLT recipients seem to have a more sustained decline in eGFR when compared with DDLT recipients.

Risk factors of acute renal failure after orthotopic liver transplantation: single-center experience

BACKGROUND

Acute renal failure (ARF) is one of the most significant complications of orthotopic liver transplantation (OLT), associated with increased mortality rate and the development of chronic renal dysfunction. The aim of the study was to determine the perioperative risk factors for ARF in patients without previous history of renal disease who are undergoing OLT.

MATERIALS AND METHODS

Forty-six patients who developed ARF after OLT performed in 1 transplant center were included in the study, and 52 consecutive patients without that complication served as a control group. Renal dysfunction was defined as a glomerular filtration rate <60 mL/min/1.73 m(2). The data concerning preoperative diseases, perioperative renal function, first-line immunosuppressive therapy, and blood transfusion requirement were retrospectively analyzed and compared among groups. Logistic regression modeling was used to determine risk factors for ARF.

RESULTS

Patients who developed ARF were significantly older (mean age 53.3 vs 46.3 years, P = .057), had higher level of preoperative (0.79 vs 0.71 mg/dL, P = .0062) and intraoperative (0.85 vs 0.74 mg/dL, P = .0045) creatinine. The risk factors for ARF were intraoperative and 24-hour post-transplant creatinine level >0.9 mg/dL and high-dose tacrolimus-based immunosuppression. Transfusion of ≤6 units of red blood cells diminished the risk of ARF. Sex and preoperative diseases were not predictive to ARF in our regression models.

CONCLUSION

Careful operative technique with low blood loss and immunosuppressive therapy of low nephrotoxic potential should be recommended in older patients to diminish the risk of renal dysfunction after orthotopic liver transplantation. Patients with higher levels of perioperative creatinine should be considered to have first-line immunosuppression without calcineurin inhibitors or with low-dose immunosuppressants of known nephrotoxic potential.

Disrupted Renal Mitochondrial Homeostasis after Liver Transplantation in Rats

BACKGROUND

Suppressed mitochondrial biogenesis (MB) contributes to acute kidney injury (AKI) after many insults. AKI occurs frequently after liver transplantation (LT) and increases mortality. This study investigated whether disrupted mitochondrial homeostasis plays a role in AKI after LT.

METHODS

Livers were explanted from Lewis rats and implanted after 18 h cold storage. Kidney and blood were collected 18 h after LT.

RESULTS

In the kidney, oxidative phosphorylation (OXPHOS) proteins ATP synthase-β and NADH dehydrogenase-3 decreased 44% and 81%, respectively, with marked reduction in associated mRNAs. Renal PGC-1α, the major regulator of MB, decreased 57% with lower mRNA and increased acetylation, indicating inhibited synthesis and suppressed activation. Mitochondrial transcription factor-A, which controls mtDNA replication and transcription, protein and mRNA decreased 66% and 68%, respectively, which was associated with 64% decreases in mtDNA. Mitochondrial fission proteins Drp-1 and Fis-1 and mitochondrial fusion protein mitofusin-1 all decreased markedly. In contrast, PTEN-induced putative kinase 1 and microtubule-associated protein 1A/1B-light chain 3 increased markedly after LT, indicating enhanced mitophagy. Concurrently, 18- and 13-fold increases in neutrophil gelatinase-associated lipocalin and cleaved caspase-3 occurred in renal tissue. Both serum creatinine and blood urea nitrogen increased >2 fold. Mild to moderate histological changes were observed in the kidney, including loss of brush border, vacuolization of tubular cells in the cortex, cast formation and necrosis in some proximal tubular cells. Finally, myeloperoxidase and ED-1 also increased, indicating inflammation.

CONCLUSION

Suppression of MB, inhibition of mitochondrial fission/fusion and enhancement of mitophagy occur in the kidneys of recipients of liver grafts after long cold storage, which may contribute to the occurrence of AKI and increased mortality after LT.

Acute kidney injury after liver transplantation: incidence and mortality

INTRODUCTION

Patients undergoing orthotopic liver transplantation often present with acute kidney injury (AKI) in the postoperative period. It has been associated with a greater number of complications and high mortality rates. The goal of this study was to determine the incidence of AKI during the early posttransplant period and mortality in patients undergoing orthotopic liver transplantation in our hospital.

PATIENTS AND METHODS

In this retrospective cohort study, we reviewed the medical records of all patients aged >18 years undergoing liver transplantation from April 2008 to April 2011. The exclusion criteria were a glomerular filtration rate (estimated by using the Modification of Diet in Renal Disease formula) <60 mL/min/1.73 m(2) or AKI at the time of transplantation. AKI was defined as an increase ≥50% from preoperative baseline serum creatinine levels during the hospitalization period.

RESULTS

Of 113 selected patients, 78 (69%) were male. The mean age was 54.03 ± 9.38 years. The mean preoperative baseline creatinine level was 0.94 ± 0.15 mg/dL, and the estimated glomerular filtration rate was 87.09 ± 19.67 mL/min/1.73 m(2). The mean calculated Model for End-Stage Liver Disease score was 13. Hepatitis C serology was present in 70.8%, hepatitis B in 11.5%, hepatocellular carcinoma in 75.2%, and alcohol abuse in 31.9% of patients. The incidence of AKI was 56.6% (64 of 113 patients). The main risk factors for AKI were Model for End-Stage Liver Disease score and diuretic use at baseline. Renal replacement therapy (RRT) was performed in 19.5% (22 of 113) of patients. The hospital mortality rate in the group with AKI was 25% (16 of 64 patients) and 6.1% (3 of 49 patients) between patients without AKI (odds ratio, 5.11 [confidence interval, 1.39-18.7]; P < .01]. Among patients who underwent RRT, the in-hospital mortality rate was 54.5% (12 of 22 patients) compared with 7.7% (7 of 91 patients) from the other remaining patient cohort (odds ratio, 14.40 [confidence interval, 4.60-45.00]; P < .01).

CONCLUSIONS

There was a high incidence of AKI in patients undergoing liver transplantation and an increased risk of mortality among patients who needed RRT.

Comparison of RIFLE and AKIN criteria in the evaluation of the frequency of acute kidney injury in post-liver transplantation patients

BACKGROUND

Acute renal dysfunction is presented quite often after orthotopic liver transplantation (LT), with a reported incidence of 12-64%. The "RIFLE" criteria were introduced in 2004 for the definition of acute kidney injury (AKI) in critically ill patients, and a revised definition was proposed in 2007 by the Acute Kidney Injury Network (AKIN), introducing the AKIN criteria. The aim of this study was to record the incidence of AKI in patients after LT by both classifications and to evaluate their prognostic value on mortality.

METHODS

We retrospectively evaluated the records of patients with LT over 2 years (2011-2012) and recorded the incidence of AKI as defined by the RIFLE and AKIN criteria. Preoperative and admission severity of disease scores, duration of mechanical ventilation, intensive care unit length of stay, and 30- and 180-day survivals were also recorded.

RESULTS

Seventy-one patients were included, with an average age of 51.78 ± 10.3 years. The incidence of AKI according to the RIFLE criteria was 39.43% (Risk, 12.7%; Injury, 12.7%; Failure, 14.1%), whereas according to the AKIN criteria it was 52.1% (stage I, 22.5%; stage II, 7%; stage II 22.55%). AKI, regardless of the classification used, was related to the Model for End-Stage Liver Disease score, the volume of transfusions, the duration of mechanical ventilation, and survival. The presence of AKI was related to higher mortality, which rose proportionally with the severity of AKI as defined by the stages of either the RIFLE or the AKIN criteria.

CONCLUSIONS

AKI classifications according to the RIFLE and AKIN criteria are useful tools in the recognition and classification of the severity of renal dysfunction in patients after LT, because they are associated with higher mortality, which rises proportionally with the severity of renal disease.

Prospective Randomized Trial Comparing Hepatic Venous Outflow and Renal Function after Conventional versus Piggyback Liver Transplantation

Background

This randomized prospective clinical trial compared the hepatic venous outflow drainage and renal function after conventional with venovenous bypass (n = 15) or piggyback (n = 17) liver transplantation.

Methods

Free hepatic vein pressure (FHVP) and central venous pressure (CVP) measurements were performed after graft reperfusion. Postoperative serum creatinine (Cr) was measured daily on the first week and on the 14^th, 21^st and 28^th postoperative days (PO). The prevalence of acute renal failure (ARF) up to the 28th PO was analyzed by RIFLE-AKIN criteria. A Generalized Estimating Equation (GEE) approach was used for comparison of longitudinal measurements of renal function.

Results

FHVP-CVP gradient > 3 mm Hg was observed in 26.7% (4/15) of the patients in the conventional group and in 17.6% (3/17) in the piggyback group (p = 0.68). Median FHVP-CVP gradient was 2 mm Hg (0–8 mmHg) vs. 3 mm Hg (0–7 mm Hg) in conventional and piggyback groups, respectively (p = 0.73). There is no statistically significant difference between the conventional (1/15) and the piggyback (2/17) groups regarding massive ascites development (p = 1.00). GEE estimated marginal mean for Cr was significantly higher in conventional than in piggyback group (2.14 ± 0.26 vs. 1.47 ± 0.15 mg/dL; p = 0.02). The conventional method presented a higher prevalence of severe ARF during the first 28 PO days (OR = 3.207; 95% CI, 1.010 to 10.179; p = 0.048).

Conclusion

Patients submitted to liver transplantation using conventional or piggyback methods present similar results regarding venous outflow drainage of the graft. Conventional with venovenous bypass technique significantly increases the harm of postoperative renal dysfunction.

Trial Registration

ClinicalTrials.gov https://clinicaltrials.gov/ct2/show/NCT01707810

Risk factors of postoperative acute kidney injury in patients undergoing esophageal cancer surgery

OBJECTIVE

The purpose of this study was to identify perioperative risk factors for postoperative acute kidney injury (AKI) in patients undergoing esophageal cancer surgery.

DESIGN

A retrospective analysis of the prospectively collected medical data.

SETTING

A tertiary care university hospital.

PARTICIPANTS

All consecutive adult patients (n=595) who underwent elective esophageal surgery for cancer between January 2005 and April 2012.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

AKI was defined by the AKI Network criteria based on serum creatinine changes within the first 48 hours after esophageal cancer surgery. The relationship between perioperative variables and AKI was evaluated using multivariate logistic regression. Postoperative AKI developed in 210 (35.3%) patients. Risk factors for AKI were body mass index (odds ratio [OR] 1.07; 95% confidence interval [CI] 1.01-1.14), preoperative serum albumin level (OR 0.52; 95% CI 0.33-0.84), use of angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers (OR 1.35; 95% CI 1.05-1.75), colloid infusion during surgery (OR 1.11; 95% CI 1.06-1.18), and postoperative 2-day C-reactive protein (OR 1.05; 95% CI 1.01-1.09). Postoperative AKI was associated with prolonged length of hospital stay.

CONCLUSIONS

Postoperative AKI is common in patients undergoing esophageal surgery for cancer. Closer evaluation and monitoring in patients with risk factors for AKI may be warranted.

Postoperative kidney injury does not decrease survival after liver transplantation

PURPOSE

To explore the effect of acute kidney injury (AKI) on long-term survival after conventional orthotopic liver transplantation (OLT) without venovenous bypass (VVB).

METHODS

A retrospective cohort study was carried out on 153 patients with end-stage liver diseases transplanted by the Department of General Surgery and Liver Transplantation of the University of Pernambuco, from August, 1999 to December, 2009. The Kaplan-Meier survival estimates and log-rank test were applied to explore the association between AKI and long-term patient survival, and multivariate analyses were applied to control the effect of other variables.

RESULTS

Over the 12.8-year follow-up, 58.8% patients were alive with a median follow-up of 4.5-year. Patient 1-, 2-, 3- and 5-year survival were 74.5%, 70.6%, 67.9% and 60.1%; respectively. Early postoperative mortality was poorer amongst patients who developed AKI (5.4% vs. 20%, p=0.010), but long-term 5-year survival did not significantly differed between groups (51.4% vs. 65.3%; p=0.077). After multivariate analyses, AKI was not significantly related to long-term survival and only the intraoperative transfusion of red blood cells was significantly related to this outcome (non-adjusted Exp[b]=1.072; p=0.045).

CONCLUSION

The occurrence of postoperative acute kidney injury did not independently decrease patient survival after orthotopic liver transplantation without venovenous bypass in this data from northeast Brazil.

Acute kidney injury after orthotopic liver transplantation

Acute kidney injury (AKI), one of the most frequent complications in the early period after liver transplantation, causes serious obstacles in the management of these patients affecting their outcomes. We studied retrospectively 79 subjects who underwent orthotopic liver transplantation (OLT). AKI was defined as an elevation of serum creatinine 1.5 times above baseline or an absolute serum creatinine level > 2 mg/dL. Our aim was to analyze the incidence, correlation with prior renal impairment, outcomes of AKI after OLT. Twenty-two patients (29.3%) developed AKI after OLT with 31.81% of the requiring renal replacement therapy. Among patients with AKI the duration of mechanical ventilation was prolonged (P = .001), length of stay in the intensive care unit was greater (P = .001), infections were more common (P = .016), and 30-day and 1-year mortality rates higher (P = .018). Logistic regression analysis showed post-OLT AKI to be an independent risk factor for 1-year mortality after OLT.

Invasive mechanical ventilation as a risk factor for acute kidney injury in the critically ill: a systematic review and meta-analysis

Introduction

Mechanical ventilation (MV) is commonly regarded as a risk factor for acute kidney injury (AKI) in the critically ill. We investigated the strength of this association and whether settings of tidal volume (Vt) and positive end-expiratory pressure (PEEP) affect the risk for AKI.

Methods

We performed a systematic review and meta-analysis using studies found by searching MEDLINE, EMBASE, and references in relevant reviews and articles. We included studies reporting on a relation between the use of invasive MV and subsequent onset of AKI, or comparing higher with lower Vt or PEEP and subsequent onset of AKI. All studies clearly stating that MV was initiated after onset of AKI were excluded. We extracted the proportion with and without MV and AKI. We included 31 studies on invasive MV.

Results

The pooled odds ratio (OR) for the overall effect of MV on AKI was 3.16 (95% CI 2.32 to 4.28, P <0.001). Nearly all subgroups showed that MV increases the risk for AKI. The pooled OR for studies with a multivariate analysis including MV as a risk factor for AKI was 3.58 (95% CI 1.85 to 6.92; P <0.001). Different settings of Vt and PEEP showed no effect.

Conclusions

Invasive MV is associated with a threefold increase in the odds of developing AKI and various Vt or PEEP settings do not modify this risk. The latter argues in favour of a haemodynamic origin of AKI during MV.

Role of MELD score and serum creatinine as prognostic tools for the development of acute kidney injury after liver transplantation

Background

The role of the Model for End-Stage Liver Disease (MELD) score in predicting complications, such as Acute Kidney Injury (AKI), after orthotopic liver transplantation (OLT) has yet to be evaluated and serum creatinine may be too heavily weighted in the existing MELD formula, since it has many pitfalls in cirrhotic patients.

Methods

Retrospective data of the perioperative period from consecutive adult OLTs performed from January to December 2009 were recorded. Univariate and multivariate analysis were performed to analyze the risk factors for AKI and mortality after OLT.

Results

There were 114 OLTs performed in the study period, 22 (19,2%) were submitted to dialysis prior OLT and were excluded from the analysis for AKI. The median age was 52 years and 66% were male. Median creatinine value was 0.85mg/dL and MELD was 19. Fifty-two of the 92 patients (56,5%) developed AKI in the first 72 hours after OLT. The only independent risk factor for AKI was calculated MELD and when the components of the MELD score were analyzed, INR had a much stronger impact in predicting AKI then serum creatinine. Overall mortality rate was 32,5% and anesthesia duration was the only variable associated with higher mortality rate.

Conclusions

Although MELD score seems to have a good performance in predicting AKI after OLT, serum creatinine had no impact on its prediction despite its importance on MELD calculation. Modifying the MELD score, which could include novel AKI biomarkers, may improve its prognostic accuracy and provide a better tool for public health planning.

Renal dysfunction in liver transplant recipients: evaluation of the critical issues

Major progress has been made in the field of liver transplantation since the first procedure was performed nearly 50 years ago. Despite these improvements, renal dysfunction before and after liver transplantation remains a major complicating factor associated with increased health care costs, morbidity, and mortality. Creatinine-based estimates of renal function are inaccurate in the setting of end-stage liver disease and often lead to underdiagnosis and late intervention. This issue is critical in that it is important to understand both the etiology and chronicity of renal dysfunction before liver transplantation because the treatment clearly varies, especially with respect to simultaneous liver-kidney (SLK) transplantation. Because of the scarcity of available grafts, identifying appropriate candidates for SLK transplantation is crucial. Hepatorenal syndrome is common in liver transplant candidates; however, other etiologies of renal dysfunction need to be considered. Renal dysfunction after liver transplantation is common and may have an acute or chronic presentation. Although calcineurin inhibitors (CNIs) have been associated with post-liver transplant nephrotoxicity, their role may be overestimated, and other contributing etiologies should remain in a clinician's differential diagnosis. Alternatives to CNIs have been evaluated; however, a safe immunosuppressive regimen that achieves the preservation of renal function in liver transplant recipients remains to be established. In this review of the literature, renal dysfunction in the setting of liver transplantation is evaluated, and the critical issues that are barriers to improved outcomes are highlighted.

Preditores de injúria renal aguda em pacientes submetidos ao transplante ortotópico de fígado convencional sem desvio venovenoso

RADICAL: Injúria renal aguda é uma das complicações mais comuns do transplante ortotópico de fígado. A ausência de critério universal para sua definição nestas condições dificulta as comparações entre os estudos. A técnica convencional para o transplante consiste na excisão total da veia cava inferior retro-hepática durante a hepatectomia nativa. Controvérsias sobre o efeito da técnica convencional sem desvio venovenoso na função renal continuam. OBJETIVO: Estimar a incidência e os fatores de risco de injúria renal aguda entre os receptores de transplante ortotópico de fígado convencional sem desvio venovenoso. MÉTODOS: Foram avaliados 375 pacientes submetidos a transplante ortotópico de fígado. Foram analisadas as variáveis pré, intra e pós-operatórias em 153 pacientes submetidos a transplante ortotópico de fígado convencional sem desvio venovenoso. O critério para a injúria renal aguda foi valor da creatinina sérica > 1,5 mg/dl ou débito urinário < 500 ml/24h dentro dos primeiros três dias pós-transplante. Foi realizada análise univariada e multivariada por regressão logística. RESULTADOS: Todos os transplantes foram realizados com enxerto de doador falecido. Sessenta pacientes (39,2%) apresentaram injúria renal aguda. Idade, índice de massa corpórea, escore de Child-Turcotte-Pugh, ureia, hipertensão arterial sistêmica e creatinina sérica pré-operatória apresentaram maiores valores no grupo injúria renal aguda. Durante o período intraoperatório, o grupo injúria renal aguda apresentou mais síndrome de reperfusão, transfusão de concentrado de hemácias, plasma fresco e plaquetas. No pós-operatório, o tempo de permanência em ventilação mecânica e creatinina pós-operatória também foram variáveis, com diferenças significativas para o grupo injúria renal aguda. Após regressão logística, a síndrome de reperfusão, a classe C do Child-Turcotte-Pugh e a creatinina sérica pós-operatória apresentaram diferenças. CONCLUSÃO: Injúria renal aguda após transplante ortotópico de fígado convencional sem desvio venovenoso é uma desordem comum, mas apresenta bom prognóstico. Síndrome de reperfusão, creatinina sérica no pós-operatório e Child C são fatores associados a injúria renal aguda pós-transplante ortotópico de fígado convencional sem desvio venovenoso.