Rifle Criteria for Acute Kidney Dysfunction Following Liver Transplantation: Incidence and Risk Factors

Development of a prediction index for persistent acute kidney injury following orthotopic liver transplant

INTRODUCTION AND OBJECTIVES

Acute kidney injury (AKI) is a common complication of orthotopic liver transplantation (OLT). This study aimed to identify factors associated with persistent AKI (pAKI) and to develop a risk index. The impact of pAKI on mortality and renal function over a 5-year period was also assessed.

MATERIALS AND METHODS

In this retrospective cohort study, adult OLT recipients were included. pAKI was defined as AKI lasting >72 hours. Logistic regression identified pAKI-associated factors, which were used to create a risk index. Long-term renal function was then evaluated.

RESULTS

Among 305 patients, 23 % developed pAKI. The median MELD (Model for End-stage Liver Disease) score was 17. Multivariate analysis identified male sex, reoperation, transfusion of >6 units of red blood cells, anhepatic time >50 minutes, and norepinephrine use >0.25 mcg/kg/min as significant risk factors. The risk index assigned 3 points each to male sex and norepinephrine use, and 5 points to the remaining factors. A score ≥11 had moderate performance (AUC 0.70) and a negative predictive value of 90 %. Patients with pAKI had longer ICU and hospital stays and higher in-hospital mortality. At 5 years, overall mortality did not differ significantly, but those with pAKI had a 10 ml/min/1.73m² lower eGFR.

CONCLUSIONS

pAKI is a frequent OLT complication, negatively affecting short-term outcomes and long-term renal function. The proposed risk index effectively identifies patients at low risk, supporting targeted monitoring and prevention.

Postoperative Blood Pressure Deficit and Acute Kidney Injury After Liver Transplant

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

[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.

Management of Acute Kidney Injury/Renal Replacement Therapy in the Intensive Care Unit

Common causes of acute kidney injury (AKI) in the ICU setting include acute tubular necrosis (due to shock, hemolysis, rhabdomyolysis, or procedures that compromise renal perfusion), abdominal compartment syndrome, urinary retention, and interstitial nephritis. Treatment is geared toward addressing the underlying cause. Dialysis may be required if renal injury does not resolve. Early initiation of dialysis based on the stage of AKI alone has not been shown to provide a mortality benefit. Dialysis modalities are based on the dialysis indication and the patient's clinical status. Providers should pay close attention to nutritional requirements and medication dosing according to renal function and dialysis modality.

Association of acidosis with coagulopathy and transfusion requirements in liver transplantation

The relationship between acidosis and coagulopathy has long been described in vitro and in trauma patients, but not yet in orthotopic liver transplantation (OLT). The association of metabolic acidosis with coagulopathy and with transfusion requirements was evaluated in patients submitted to OLT. Changes in acid-base and coagulation parameters were analyzed by repeated measures. Regression analyses [adjusted for sex, age, model for end stage liver disease (MELD) score, and baseline values of hemoglobin, fibrinogen, international normalized ratio, platelets] determined the association of acid-base parameters with coagulation markers and transfusion requirement. We included 95 patients, 66% were male, 49.5% of the patients had hepatocellular carcinoma and the mean MELD score was 20.4 (SD 8.9). The values of all the coagulation and acid-base parameters significantly changed during OLT, particularly in the reperfusion phase. After adjustments for baseline parameters, the decrease in pH and base excess (BE) values were associated with a decrease in fibrinogen levels (mean decrease of fibrinogen level = 14.88 mg/dL per 0.1 unit reduction of pH values and 3.6 mg/dL per 1 mmol/L reduction of BE levels) and an increase in red blood cells transfusion (2.16 units of RBC per 0.1 unit reduction of pH and 0.38 units of RBC per 1 mmol/L reduction of BE levels). Among multiple factors potentially associated with adverse outcomes, decreasing pH levels were independently associated with the length of hospitalization but not with in-hospital mortality. Metabolic acidosis is independently associated with decreased fibrinogen levels and increased intraoperative transfusion requirement during OLT. Awareness of that association may improve treatment strategies to reduce intraoperative bleeding risk in OLT.

Acute Kidney Injury After Liver Transplant: Incidence, Risk Factors, and Impact on Patient Outcomes

OBJECTIVES

Acute kidney injury is a frequent complication of liver transplant. Here, we assessed the rate and contributing factors of acute kidney injury and need for renal replacement therapy in patients undergoing liver transplant at a transplant center in Tehran, Iran.

MATERIAL AND METHODS

We identified all patients who underwent liver transplant at the Imam Khomeini Hospital Complex from March 2018 to March 2019 and who were followed for 3 months after transplant. Acute kidney injury was defined based on the Acute Kidney Injury Network criteria. We collected demographic and pretransplant, intraoperative, and posttransplant data. Univariable and multivariable models were applied to explore independent risk factors for acute kidney injury incidence and need for renal replacement therapy.

RESULTS

Our study included 173 deceased donor liver transplant recipients. Rates of incidence of acute kidney injury and need for renal replacement therapy were 68.2% and 14.5%, respectively. The 3-month mortality rate among those with severe and mild or moderate acute kidney injury was 44.0% (14/25) and 9.7% (9/ 93), respectively (P < .001). Multivariable analyses indicated that serum albumin (relative risk of 0.55; 95% confidence interval, 0.34-0.87; P = .021), baseline serum creatinine (relative risk of 2.11; 95% confidence interval, 1.56-2.90; P = .037), and intraoperative mean arterial pressure (relative risk of 0.76; 95% confidence interval, 0.63-0.82; P = .008) were independent factors for predicting posttransplant acute kidney injury. Independent risk factors for requiring renal replacement therapy were pretransplant serum creatinine (relative risk of 1.99; 95% confidence interval, 1.89-4.47; P = .044) and intraoperative vasopressor infusion (relative risk of 1.41; 95% confidence interval, 1.38-2.00; P = .021).

CONCLUSIONS

We found a high incidence of acute kidney injury among liver transplant recipients in our center. There was a significant association between severity of acute kidney injury and 3-month and in-hospital mortality.

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.

Restrictive fluid management strategies and outcomes in liver transplantation: a systematic review

PURPOSE

Restrictive fluid management strategies have been proposed to reduce complications in liver transplant recipients. We conducted a systematic review to evaluate the effects of restrictive perioperative fluid management strategies, compared with liberal ones, on postoperative outcomes in adult liver transplant recipients. Our primary outcome was acute kidney injury (AKI). Our secondary outcomes were bleeding, mortality, and other postoperative complications.

SOURCE

We searched major databases (CINAHL, EMB Reviews, EMBASE, MEDLINE, and the grey literature) from their inception to 10 July 2018 for randomized-controlled trials (RCTs) and observational studies comparing two fluid management strategies (or observational studies reporting two outcomes with available data on fluid volume received) in adult liver transplant recipients. Study selection, data abstraction, and risk of bias assessment were performed by at least two investigators. Data from RCTs were pooled using risk ratios (RR) and mean differences (MD) with random-effect models.

PRINCIPAL FINDINGS

We found seven RCTs and 29 observational studies. Based on RCTs, fluid management strategies did not have any effect on AKI, mortality, or any other postoperative complications. Intraoperative RCTs suggested that a restrictive fluid management strategy reduced pulmonary complications (RR, 0.69; 95% confidence interval [CI], 0.47 to 0.99; n = 283; I² = 27%), duration of mechanical ventilation (MD, -13.04 hr; 95% CI, -22.2 to -3.88; n = 130; I² = 0%) and blood loss (MD, -1.14 L; 95% CI, -1.72 to -0.57; n = 151; I² = 0%).

CONCLUSION

Based on low or very low levels of evidence, we did not find any association between restrictive fluid management strategies and AKI, but we observed possible protective effects of intraoperative restrictive fluid management strategies on other outcomes.

TRIAL REGISTRATION

PROSPERO (CRD42017054970); registered 18 May, 2017.

Intraoperative Hepatic Blood Inflow Can Predict Early Acute Kidney Injury following DCD Liver Transplantation: A Retrospective Observational Study

Purpose

Acute kidney injury (AKI) is a major and severe complication following donation-after-circulatory-death (DCD) liver transplantation (LT) and is associated with increased postoperative morbidity and mortality. However, the risk factors and the prognosis factors of AKI still need to be further explored, and the relativity of intraoperative hepatic blood inflow (HBI) and AKI following LT has not been discussed yet. The purpose of this study was to investigate the correlation between HBI and AKI and to construct a prediction model of early acute kidney injury (EAKI) following DCD LT with the combination of HBI and other clinical parameters.

Methods

Clinical data of 132 patients who underwent DCD liver transplantation at the first hospital of China Medical University from April 2005 to March 2017 were analyzed. Data of 105 patients (the first ten years of patients) were used to develop the prediction model. Then we assessed the clinical usefulness of the prediction models in the validation cohort (27 patients). EAKI according to Kidney Disease Improving Global Outcomes (KDIGO) criteria based on serum creatinine increase during 7-day of postoperative follow-up.

Results

After Least Absolute Shrinkage and Selection Operator (LASSO) regression and simplification, a simplified prediction model consisting of the Child-Turcotte-Pugh (CTP) score (p=0.033), anhepatic phase (p=0.014), packed red blood cell (pRBC) transfusion (p=0.027), and the HBI indexed by height (HBI/h) (p=0.002) was established. The C-indexes of the model in the development and validation cohort were 0.823 [95% CI, 0.738-0.908] and 0.921 [95% CI, 0.816-1.000], respectively.

Conclusions

In this study, we demonstrated the utility of HBI/h as a predictor for EAKI following DCD LT, as well as the clinical usefulness of the prediction model through the combination of the CTP score, anhepatic phase, pRBC transfusion and HBI/h.

Urinary [TIMP-2] × [IGFBP-7] for predicting acute kidney injury in patients undergoing orthotopic liver transplantation

BACKGROUND

The product of the concentrations of urinary tissue inhibitor of metalloproteinases-2 and insulin-like growth factor binding protein-7 (urinary [TIMP-2] × [IGFBP-7]) has been suggested as biomarker for early detection of acute kidney injury (AKI) in various clinical settings. However, the performance of urinary [TIMP-2] × [IGFBP-7] to predict AKI has never been assessed in patients undergoing orthotopic liver transplantation (OLT). Thus, the aim of this study was to assess the early predictive value of urinary [TIMP-2] × [IGFBP-7] for the development of AKI after OLT.

METHODS

In this observational study, urinary [TIMP-2] × [IGFBP-7] was measured in samples from adult OLT patients. AKI was diagnosed and classified according to KDIGO criteria. Areas under the receiver operating curves (AUC) were calculated to assess predictive values of urinary [TIMP-2] × [IGFBP-7] for the development of AKI.

RESULTS

Forty patients (mean age 55 ± 8 years) were included. Twenty-eight patients (70%) developed AKI stage 1, 2, or 3 within 48 h after OLT. Urinary [TIMP-2] × [IGFBP-7] was not predictive for AKI at the end of OLT (AUC: 0.54, CI [0.32-0.75], P = 0.72), at day 1 (AUC: 0.60, CI [0.41-0.79], P = 0.31), or day 2 after OLT (AUC: 0.63, CI [0.46-0.8], P = 0.18).

CONCLUSION

Based on our results, routine clinical use of urinary [TIMP-2] × [IGFBP-7] cannot be recommended for risk assessment of AKI in patients undergoing OLT.

Incidence and Impact of Acute Kidney Injury after Liver Transplantation: A Meta-Analysis

BACKGROUND

The study's aim was to summarize the incidence and impacts of post-liver transplant (LTx) acute kidney injury (AKI) on outcomes after LTx.

METHODS

A literature search was performed using the MEDLINE, EMBASE and Cochrane Databases from inception until December 2018 to identify studies assessing the incidence of AKI (using a standard AKI definition) in adult patients undergoing LTx. Effect estimates from the individual studies were derived and consolidated utilizing random-effect, the generic inverse variance approach of DerSimonian and Laird. The protocol for this systematic review is registered with PROSPERO (no. CRD42018100664).

RESULTS

Thirty-eight cohort studies, with a total of 13,422 LTx patients, were enrolled. Overall, the pooled estimated incidence rates of post-LTx AKI and severe AKI requiring renal replacement therapy (RRT) were 40.7% (95% CI: 35.4%⁻46.2%) and 7.7% (95% CI: 5.1%⁻11.4%), respectively. Meta-regression showed that the year of study did not significantly affect the incidence of post-LTx AKI (p = 0.81). The pooled estimated in-hospital or 30-day mortality, and 1-year mortality rates of patients with post-LTx AKI were 16.5% (95% CI: 10.8%⁻24.3%) and 31.1% (95% CI: 22.4%⁻41.5%), respectively. Post-LTx AKI and severe AKI requiring RRT were associated with significantly higher mortality with pooled ORs of 2.96 (95% CI: 2.32⁻3.77) and 8.15 (95%CI: 4.52⁻14.69), respectively. Compared to those without post-LTx AKI, recipients with post-LTx AKI had significantly increased risk of liver graft failure and chronic kidney disease with pooled ORs of 3.76 (95% CI: 1.56⁻9.03) and 2.35 (95% CI: 1.53⁻3.61), respectively.

CONCLUSION

The overall estimated incidence rates of post-LTx AKI and severe AKI requiring RRT are 40.8% and 7.0%, respectively. There are significant associations of post-LTx AKI with increased mortality and graft failure after transplantation. Furthermore, the incidence of post-LTx AKI has remained stable over the ten years of the study.

Critical Care Management of Living Donor Liver Transplants

This article represents a review of the postoperative management of donors and recipients after living donor liver transplant, including monitoring, liberation from mechanical ventilation, nutritional support, and pain control. Vascular complications, such as biliary and sepsis, and bleeding are also discussed. Finally, commonly used immunosuppression and antimicrobial prophylaxes are reviewed.

Acute Kidney Injury Before and After Liver Transplant

The development of acute kidney injury in the setting of liver disease is a significant event both before and after liver transplant. Whether acute kidney injury is the cause of or merely associated with worse outcomes, the development of renal failure is significant from a prognostic as well as from a diagnostic and therapeutic standpoint. Although not every etiology is reversible, there are number of etiologies that are correctable, to include hypovolemia, nephrotoxic medications, and acute tubular necrosis. In the post-liver transplant period, renal failure is associated with graft failure as well as worse outcomes overall. Prompt recognition, workup, and intervention can significantly impact outcomes and survival both before and after liver transplant.

Comparison of macrophage migration inhibitory factor and neutrophil gelatinase-associated lipocalin-2 to predict acute kidney injury after liver transplantation: An observational pilot study

Introduction

Several biomarkers have been suggested as early predictors of acute kidney injury (AKI) after orthotopic liver transplantation (OLT). Neutrophil gelatinase-associated lipocalin-2 (NGAL) appears to be a promising predictor of AKI after OLT, but the clinical benefit remains to be proven. Recently, systemic macrophage migration inhibitory factor (MIF) has been proposed as early indicator for requirement of renal replacement therapy after OLT. The aim of this prospective, observational pilot study was to compare the predictive values of serum and urinary MIF for severe AKI after OLT to those of serum and urinary NGAL.

Methods

Concentrations of MIF and NGAL were measured in serum and urine samples collected from patients undergoing OLT. Acute kidney injury was classified according to the KDIGO criteria, with stages 2 and 3 summarized as severe AKI. Areas under the receiver operating curves (AUC) were calculated to assess predictive values of MIF and NGAL for the development of severe AKI.

Results

Forty-five patients (mean age 55±8 years) were included. Nineteen patients (38%) developed severe AKI within 48 hours after reperfusion. At the end of OLT, serum MIF was predictive of severe AKI (AUC 0.73; 95% confidence intervals, CI 0.55–0.90; P = 0.03), whereas urinary MIF, serum NGAL, and urinary NGAL were not. On the first postoperative day, serum MIF (AUC 0.78; CI 0.62–0.93; P = 0.006), urinary MIF (AUC 0.71; CI 0.53–0.88; P = 0.03), and urinary NGAL (AUC 0.79; CI 0.64–0.93; P = 0.02) were predictive for severe AKI, while serum NGAL was not.

Conclusion

In the setting of OLT, MIF and NGAL had similar predictive values for the development of severe AKI.

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 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.

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.

Acute Renal Injury Evaluation After Liver Transplantation: With RIFLE Criteria

BACKGROUND

The aim of this study was to identify acute renal injury (ARI) through the use of RIFLE (risk, injury, failure, loss, end-stage kidney disease) criteria and to investigate perioperative risk factors for ARI in liver transplantation (LT).

METHODS

We reviewed medical records of adult LT patients retrospectively. Postoperative ARI was staged with RIFLE criteria by the 1st and 7th days of the surgery.

RESULTS

We analyzed 440 adult LT patients, categorized as risk (R), injury (I), or failure (F) according to the RIFLE criteria. In this study, in the first postoperative day, incidence of ARI was 7.95%; all of them were R-class, and, on the 7th day, the incidence of ARI was 7.27%, as R-class 6.59% and I-class 0.68%. Significant risk factors were detected within the first postoperative day including pre-operative hemoglobin levels <9 g/dL (P = .019), intra-operative transfusion of red blood cells (RBCs) (P = .049) and fresh-frozen plasma (FFP) (P = .049), blood loss (P = .011), and post-reperfusion syndrome (P = .023). Multivariate analysis revealed risk factors for ARI as RBCs (odds ratio [OR], 1.049; P = .247) and FFP (OR, 1.017; P = .627) transfusion and blood loss (OR, 1.000; P = .021) (blood loss OR: 0.9996952300184; 95% confidence interval: 0.9994356774026 to 0.999548500399). The only significant risk factor for the 7th postoperative day was the Model for End-Stage Liver Disease (MELD) score (>20) (P = .002).

CONCLUSIONS

This study showed that RBC and FFP transfusion, perioperative blood loss, and MELD score >20 are risk factors for LT-related ARI. Also normalization of hemoglobin levels with non-blood products in patients with preoperative low hemoglobin levels can diminish the need for RBC and that can prevent ARI.

Acute Kidney Injury in the Surgical Patient

Perioperative acute kidney injury (AKI) is a common, morbid, and costly surgical complication. Current efforts to understand and manage AKI in surgical patients focus on prevention, mitigation of further injury when AKI has occurred, treatment of associated conditions, and facilitation of renal recovery. Lesser severity AKI is now understood to be much more common, and more morbid, than was previously thought. The ability to detect AKI within hours of onset would be helpful in protecting the kidney and in preserving renal function, and several imaging and biomarker modalities are currently being evaluated.

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.

Clinical Risk Scoring Models for Prediction of Acute Kidney Injury after Living Donor Liver Transplantation: A Retrospective Observational Study

Acute kidney injury (AKI) is a frequent complication of liver transplantation and is associated with increased mortality. We identified the incidence and modifiable risk factors for AKI after living-donor liver transplantation (LDLT) and constructed risk scoring models for AKI prediction. We retrospectively reviewed 538 cases of LDLT. Multivariate logistic regression analysis was used to evaluate risk factors for the prediction of AKI as defined by the RIFLE criteria (RIFLE = risk, injury, failure, loss, end stage). Three risk scoring models were developed in the retrospective cohort by including all variables that were significant in univariate analysis, or variables that were significant in multivariate analysis by backward or forward stepwise variable selection. The risk models were validated by way of cross-validation. The incidence of AKI was 27.3% (147/538) and 6.3% (34/538) required postoperative renal replacement therapy. Independent risk factors for AKI by multivariate analysis of forward stepwise variable selection included: body-mass index >27.5 kg/m2 [odds ratio (OR) 2.46, 95% confidence interval (CI) 1.32-4.55], serum albumin <3.5 mg/dl (OR 1.76, 95%CI 1.05-2.94), MELD (model for end-stage liver disease) score >20 (OR 2.01, 95%CI 1.17-3.44), operation time >600 min (OR 1.81, 95%CI 1.07-3.06), warm ischemic time >40 min (OR 2.61, 95%CI 1.55-4.38), postreperfusion syndrome (OR 2.96, 95%CI 1.55-4.38), mean blood glucose during the day of surgery >150 mg/dl (OR 1.66, 95%CI 1.01-2.70), cryoprecipitate > 6 units (OR 4.96, 95%CI 2.84-8.64), blood loss/body weight >60 ml/kg (OR 4.05, 95%CI 2.28-7.21), and calcineurin inhibitor use without combined mycophenolate mofetil (OR 1.87, 95%CI 1.14-3.06). Our risk models performed better than did a previously reported score by Utsumi et al. in our study cohort. Doses of calcineurin inhibitor should be reduced by combined use of mycophenolate mofetil to decrease postoperative AKI. Prospective randomized trials are required to address whether artificial modification of hypoalbuminemia, hyperglycemia and postreperfusion syndrome would decrease postoperative AKI in LDLT.

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 14th, 21st and 28th 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.

Macrophage migration inhibitory factor as a potential predictor for requirement of renal replacement therapy after orthotopic liver transplantation

Acute kidney injury (AKI) after orthotopic liver transplantation (OLT) is associated with a poor clinical outcome. Because there is no specific treatment for postoperative AKI, early recognition and prevention are fundamental therapeutic approaches. Concentrations of the proinflammatory cytokine macrophage migration inhibitory factor (MIF) are elevated in patients with kidney disease. We hypothesized that plasma MIF concentrations would be greater in patients developing AKI after OLT compared with patients with normal kidney function. Twenty-eight patients undergoing OLT were included in the study. Kidney injury was classified according to AKI network criteria. Fifteen patients (54%) developed severe AKI after OLT, 11 (39%) requiring renal replacement therapy (RRT). On the first postoperative day, patients with severe AKI had greater plasma MIF concentrations (237 ± 123 ng/mL) than patients without AKI (95 ± 63 ng/mL; P < 0.001). The area under the receiver operating characteristic (ROC) curve for predicting severe AKI was 0.87 [95% confidence interval (CI), 0.69-0.97] for plasma MIF, 0.61 (95% CI, 0.40-0.79) for serum creatinine (sCr), and 0.90 (95% CI, 0.72-0.98) for delta serum creatinine (ΔsCr). Plasma MIF (P = 0.02) and ΔsCr (P = 0.01) yielded a better predictive value than sCr for the development of severe AKI. Furthermore, the area under the ROC curve to predict the requirement of RRT was 0.87 (95% CI, 0.68-0.96) for plasma MIF, 0.65 (95% CI, 0.44-0.82) for sCr, and 0.72 (95% CI, 0.52-0.88) for ΔsCr. Plasma MIF had a better predictive value than sCr for the requirement of RRT (P = 0.02). In conclusion, postoperative plasma MIF concentrations were elevated in patients who developed severe AKI after OLT. Furthermore, plasma MIF concentrations showed a good prognostic value for identifying patients developing severe AKI or requiring postoperative RRT after OLT.

Factors associated with early mortality after living-donor liver transplant

OBJECTIVES

We sought to identify the risk factors associated with the early mortality after a living-donor liver transplant.

MATERIALS AND METHODS

Two hundred eighteen patients were recruited in this study. Potential risk factors were analyzed using univariate and multivariate analyses. A C statistic equivalent to the area under the receiver operating characteristic curve was used to assess the ability of the model to predict mortality risk during the first 3 months after a living-donor liver transplant.

RESULTS

Twenty-six recipients died within the first 3 months after a living-donor liver transplant. On a multivariate analysis, intraoperative allogeneic red blood cell transfusion and the preoperative creatinine levels were independently associated with early postoperative mortality. A prognostic model was proposed in this study (early mortality risk score = 0.107 × intraoperative allogeneic red blood cells transfusion [U] + 0.005 × preoperative creatinine concentration [μmol/L]). Three-month survival rates of patients with high and low scores were 69.8% and 95.5% (P < .001).

CONCLUSIONS

Transfusion of intraoperative allogeneic red blood cell and preoperative creatinine levels are associated with the early mortality after living-donor liver transplant. A model to predict early mortality after a living-donor liver transplant based on these risk factors was proposed in this study.

A meta-analysis of complications following deceased donor liver transplant

BACKGROUND

Liver transplantation is a complex surgery associated with high rates of postoperative complications. While national outcomes data are available, national rates of most complications are unknown.

DATA SOURCES

A systematic review of the literature reporting rates of postoperative complications between 2002 and 2012 was performed. A cohort of 29,227 deceased donor liver transplant recipients from 74 studies was used to calculate pooled incidences for 17 major postoperative complications.

CONCLUSIONS

This is the first comprehensive review of postoperative complications after liver transplantation and can serve as a guide for transplant and nontransplant clinicians. Efforts to collect national data on complications, such as through the National Surgical Quality Improvement Program, would improve the ability to provide patients with informed consent, serve as a tool for individual center performance monitoring, and provide a central source against which to measure interventions aimed at improving patient care.

National surgical quality improvement program underestimates the risk associated with mild and moderate postoperative acute kidney injury

OBJECTIVES

In a single-center cohort of surgical patients, we assessed the association between postoperative change in serum creatinine and adverse outcomes and compared the American College of Surgeons National Surgical Quality Improvement Program's definition for acute kidney injury with consensus risk, injury, failure, loss, and end-stage kidney and Kidney Disease: Improving Global Outcomes definitions.

DESIGN

Retrospective single-center cohort.

SETTING

Academic tertiary medical center.

PATIENTS

Twenty-seven thousand eight hundred forty-one adult patients with no previous history of chronic kidney disease undergoing major surgery.

INTERVENTIONS

Risk, injury, failure, loss, and end-stage kidney defines acute kidney injury as change in serum creatinine greater than or equal to 50% while Kidney Disease: Improving Global Outcomes uses 0.3 mg/dL change from the reference serum creatinine. Since National Surgical Quality Improvement Program defines acute kidney injury as serum creatinine change greater than 2 mg/dL, it may underestimate the risk associated with less severe acute kidney injury.

MEASUREMENTS AND MAIN RESULTS

The optimal discrimination limits for both percent and absolute serum creatinine changes were calculated by maximizing sensitivity and specificity along the receiver operating characteristic curves for postoperative complications and mortality. Although prevalence of risk, injury, failure, loss, and end-stage kidney-acute kidney injury was 37%, only 7% of risk, injury, failure, loss, and end-stage kidney-acute kidney injury patients would be diagnosed with acute kidney injury using the National Surgical Quality Improvement Program definition. In multivariable logistic models, patients with risk, injury, failure, loss, and end-stage kidney or Kidney Disease: Improving Global Outcomes-acute kidney injury had a 10 times higher odds of dying compared to patients without acute kidney injury. The optimal discrimination limits for change in serum creatinine associated with adverse postoperative outcomes were as low as 0.2 mg/dL while the National Surgical Quality Improvement Program discrimination limit of 2.0 mg/dL had low sensitivity (0.05-0.28).

CONCLUSIONS

Current American College of Surgeons National Surgical Quality Improvement Program definition underestimates the risk associated with mild and moderate acute kidney injury otherwise captured by the consensus risk, injury, failure, loss, and end-stage kidney and Kidney Disease: Improving Global Outcomes criteria.

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.

Incidence and relevance of acute kidney injury in patients hospitalized with acute coronary syndromes

Acute kidney injury (AKI) occurs frequently in patients with acute coronary syndromes (ACS) and is associated with adverse short- and long-term outcomes. To date, however, no standardized definition of AKI has been used for patients with ACS. As a result, information on its true incidence and the clinical and prognostic relevance according to the severity of renal function deterioration are still lacking. We retrospectively studied 3,210 patients with ACS. AKI was identified on the basis of the changes in serum creatinine during hospitalization according to the AKI Network criteria. Overall, 409 patients (13%) developed AKI: 262 (64%) had stage 1, 25 (6%) stage 2, and 122 (30%) stage 3 AKI. In-hospital mortality was greater in patients with AKI than in those without AKI (21% vs 1%; p <0.001). The adjusted risk of death increased with increasing AKI severity. Compared to no AKI, the adjusted odds ratio for death was 3.5 (95% confidence interval 1.79 to 6.83) with stage 1 AKI and 31.2 (95% confidence interval 16.96 to 57.45) with stage 2 to 3 AKI. A significant parallel increase in major adverse cardiac events was also observed comparing patients without AKI and those with stage 2 to 3 AKI. In conclusion, in patients with ACS, AKI is a frequent complication, and the graded increase of its severity, as assessed using the AKI Network classification, is associated with a progressive increased risk of in-hospital morbidity and mortality.

A critical appraisal of the accuracy of the RIFLE and AKIN classifications in defining "acute kidney insufficiency" in critically ill patients

PURPOSE

The lack of a consensus definition for acute kidney injury (AKI) has led to a great deal of discrepancies and confusion in the literature in this field. Thus, the RIFLE (Risk of renal dysfunction, Injury to the kidney, Failure of kidney function, Loss of kidney function and End-stage renal disease) and Acute Kidney Injury Network (AKIN) classifications were developed by multidisciplinary collaborative groups and were validated by experts in an international consensus conference in 2007 under an umbrella "acute kidney insufficiency" definition.

METHODS

Search in the MEDLINE and PUBMED databases for relevant literature from January 2000 to June 2011 was performed to assess the accuracy of the novel consensus definitions for AKI.

CONCLUSIONS

Both systems are based on serum creatinine level and urine output criteria and are staged in 3 severity levels. A major difference between these 2 classifications is that smaller and more rapid changes in serum creatinine are considered in the AKIN stage 1. Each AKI classification has demonstrated its ability to stratify patients according to their AKI severity and to predict outcomes. No classification system has been shown to be superior over the others. Their application in clinical studies would benefit from standardization and the new Kidney Disease Improving Global Outcomes definition of AKI was recently proposed to achieve this aim. Because these classifications do not allow earlier AKI diagnosis and do not optimize the timing of RRT initiation, they remain of moderate utility from the patient's point of view.