Update on perioperative acute kidney injury. Curr Opin Crit Care. 2016;22:370-378. [PMID: 27258664 DOI: 10.1097/mcc.0000000000000318]

Post Liver Transplant Renal Dysfunction-Evaluation, Management and Immunosuppressive Practice

Liver transplantation (LT) is an effective and lifesaving treatment for patients with end-stage liver disease and hepatocellular carcinoma. Significant improvement in intermediate and long-term survival has been possible due to advancements in immunosuppressive therapy, perioperative care, and surgical techniques. Despite these advances, metabolic complications, including diabetes mellitus, cardiovascular diseases, malignancies, and renal dysfunction, are challenging issues after LT. Acute kidney injury (AKI) and chronic kidney disease (CKD) after LT are common and result in significant morbidity and mortality. Early diagnosis of kidney injury after LT is challenging, and no technique has yet proven effective in prediction of renal dysfunction. The methods for assessing renal function range from formulas that predict glomerular filtration rate to non-invasive biomarkers. The universal adoption of the model for end-stage liver disease has a direct impact on the incidence of peri-transplant AKI and development of CKD in the long-term. Post-LT renal dysfunction is multifactorial and is usually a result of pre-transplantation comorbidities, occurrence of renal dysfunction on the waiting list, perioperative events, and post-transplant nephrotoxic immunosuppressive medication use. Early identification of patients at risk for renal dysfunction and adoption of preventive measures are crucial in the pre-transplant period. No data are currently available to suggest a surgical technique that reliably demonstrates renal protection. Nephroprotective strategies during LT follow accepted surgical practice guidelines, such as maintenance of intravascular volume and mean arterial pressure. The management of kidney disease following LT is challenging, as by the time the serum creatinine is significantly elevated, few interventions impact the course of progression. Early nephroprotective measures are strongly advised and they mostly center on delaying the administration of calcineurin inhibitors (CNIs) during the initial postoperative period, lowering CNI dosage and combining CNI with mycophenolate mofetil and everolimus. The reasons for renal failure following LT, the techniques used to diagnose it, and the therapies designed to preserve renal function both immediately and late after LT are all critically evaluated in this review.

Liver Transplantation: Protocol for Recipient Selection, Evaluation, and Assessment

Liver transplantation (LT) is the definitive therapy for patients with end-stage liver disease, acute liver failure, acute-on-chronic liver failure, hepatocellular carcinoma, and metabolic liver diseases. The acceptance of LT in Asia has been gradually increasing and so is the expertise to perform LT. Preparing a patient with cirrhosis for LT is the most important aspect of a successful LT. The preparation for LT begins with the first index decompensation for a patient with cirrhosis. Patients planned for LT should undergo a thorough screening for infections, and a complete cardiac, pulmonology, and psychosocial evaluation pre-LT. In this review, we discuss the indications and contraindications of LT and the evaluation and assessment of patients with liver disease planned for LT.

The association of pre-transplant atrial fibrillation with in-hospital outcomes in patients undergoing orthotopic liver transplantation: A propensity score matching analysis

INTRODUCTION

In this study, we sought to evaluate the prevalence and association of pre-transplant atrial fibrillation (AF) on 30-day postoperative outcomes in patients undergoing orthotopic liver transplant (OLT).

METHOD

The National Inpatient Sample Database was queried from 2011 to 2017 for relevant ICD-9 and ICD-10 procedural and diagnostic codes. Baseline characteristics and in-hospital outcomes were compared in patients who underwent OLT with AF and those without.

RESULTS

Among 45,357 patients who underwent OLT, women made up 35.8% of the overall population. The prevalence of AF before transplant was 2932 (6.5%) with a trend toward increasing prevalence, with an average annual change rate of 4.19%. Applying propensity score matching to control for potential confounding factors, there was no association between pre-transplant AF and in-hospital mortality in patients undergoing OLT, however there was a higher incidence of perioperative complications including: acute kidney injury, ventricular tachycardia, major bleeding, blood product transfusion, and septic shock.

CONCLUSION

In patients undergoing OLT, pre-transplant AF is increasing in prevalence and appears to be associated with similar in-hospital mortality but worse perioperative outcomes. Greater emphasis should be placed on AF in the preoperative cardiovascular risk stratification of patients undergoing OLT.

Association of intraoperative gross hematuria with acute kidney injury after cytoreductive surgery

Objectives

Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) has been established in the management of peritoneal carcinomatosis. Although it is still necessary to take adequate measures against major postoperative complications including acute kidney injury (AKI), consensus is lacking on how to assess and stratify risk for patients with postoperative AKI after CRS-HIPEC. The aim of this retrospective cohort study was to investigate the association of intraoperative gross hematuria as a surrogate marker of ureter injury with postoperative AKI incidence.

Methods

This retrospective cohort study investigated patients without impaired preoperative kidney function who underwent CRS-HIPEC at a single referral center, and evaluated the relationship between intraoperative gross hematuria and incidence of postoperative AKI as defined by the Kidney Disease Improving Global Outcomes practice guidelines. Logistic regression analysis was performed to calculate the odds ratio of intraoperative gross hematuria for AKI, adjusting for confounding factors and other risk factors for AKI.

Results

We enrolled 185 patients (males, 37%). Twenty-five patients developed intraoperative gross hematuria. Postoperative AKI occurred in 10 (40%) of 25 patients with hematuria and 28 (17.5%) of 160 patients without hematuria. The crude odds ratio for exposure to hematuria was 3.14 (95% confidence interval, 1.30–7.60; p=0.020) for postoperative AKI. Adjusted odds ratio as estimated by multivariate logistic regression was 4.57 (95% confidence interval, 1.55–13.45; p=0.006).

Conclusions

Intraoperative gross hematuria is significantly associated with postoperative AKI incidence after CRS-HIPEC.

–

Early detection and treatment of postoperative acute kidney injury is essential.

–

How to prevent acute kidney injury after cytoreductive surgery is unclear.

–

Intraoperative hematuria is related to postoperative acute kidney injury.

–

Hematuria is easily detectable and may reflect ureter injury.

–

This may improve long-term outcomes for patients undergoing cytoreductive surgery.

Up-regulation of VSIG4 alleviates kidney transplantation-associated acute kidney injury through suppressing inflammation and ROS via regulation of AKT signaling

Prolonged cold ischemia (CI) is a risk factor for acute kidney injury (AKI) after kidney transplantation (KT). AKI is an abrupt and rapid reduction in renal function due to multi-factors, including inflammation, oxidative stress and apoptosis. V-set immunoglobulin-domain-containing 4 (VSIG4) is a B7 family-related protein and specifically expressed in resting tissue-resident macrophages to mediate various cellular events. In the study, we attempted to explore the effects of VSIG4 on CI/KT-induced AKI in a mouse model. Our results showed that VSIG4 expression was markedly down-regulated in serum of kidney transplant recipients with acute rejection, and in renal tissues of cold ischemia-reperfusion (IR)-operated mice with AKI, which was confirmed in murine macrophages stimulated by oxygen glucose deprivation/reoxygenation (OGD/R). We then found that exogenous VSIG4 markedly ameliorated histological changes in kidney of CI/KT mice by suppressing inflammation and apoptosis through restraining nuclear factor-κB (NF-κB) and Caspase-3 activation, respectively. Oxidative stress and reactive oxygen species (ROS) accumulation in renal tissues were also mitigated by exogenous VSIG4 in CI/KT mice through improving nuclear factor-erythroid 2 related factor 2 (Nrf2) nuclear expression. The inhibitory effects of VSIG4 on inflammation, ROS generation and cell death were confirmed in OGD/R-treated macrophages, which further ameliorated oxidative damage and apoptosis in podocytes. More in vivo and in vitro studies showed that CI/KT- and OGD/R-induced AKI was further accelerated by VSIG4 knockdown. Mechanistically, VSIG4 directly interacted with AKT, and AKT activation was necessary for VSIG4 to govern all these above mentioned cellular processes. Collectively, our findings demonstrated that VSIG4 could mitigate AKI in a CI/KT mouse model, and we identified VSIG4/AKT axis as a promising therapeutic target for the treatment of the disease.

Improved Cardiovascular Tolerance to Hemorrhage after Oral Resveratrol Pretreatment in Dogs

Resveratrol has been shown to preserve organ function and improve survival in hemorrhagic shock rat models. This study investigated whether seven days of oral resveratrol could improve hemodynamic response to hemorrhage and confer benefits on risk of acute kidney injury (AKI) without inducing coagulopathy in a canine model. Twelve greyhound dogs were randomly allocated to receive oral resveratrol (1000 mg/day) or placebo for seven days prior to inducing hemorrhage until a targeted mean blood pressure of ≤40 mmHg was achieved. AKI biomarkers and coagulation parameters were measured before, immediately following, and two hours after hemorrhage. Dogs were euthanized, and renal tissues were examined at the end of the experiment. All investigators were blinded to the treatment allocation. A linear mixed model was used to assess effect of resveratrol on AKI biomarkers and coagulation parameters while adjusting for volume of blood loss. A significant larger volume of blood loss was required to achieve the hypotension target in the resveratrol group compared to placebo group (median 64 vs. 55 mL/kg respectively, p = 0.041). Although histological evidence of AKI was evident in all dogs, the renal tubular injury scores were not significantly different between the two groups, neither were the AKI biomarkers. Baseline (pre-hemorrhage) maximum clot firmness on the Rotational Thromboelastometry (ROTEM^®) was stronger in the resveratrol group than the placebo group (median 54 vs. 43 mm respectively, p = 0.009). In summary, seven days of oral resveratrol did not appear to induce increased bleeding risk and could improve greyhound dogs’ blood pressure tolerance to severe hemorrhage. Renal protective effect of resveratrol was, however, not observed.

Intraoperative Data Enhance the Detection of High-Risk Acute Kidney Injury Patients When Added to a Baseline Prediction Model

BACKGROUND

Aspects of intraoperative management (eg, hypotension) are associated with acute kidney injury (AKI) in noncardiac surgery patients. However, it is unclear if and how the addition of intraoperative data affects a baseline risk prediction model for postoperative AKI.

METHODS

With institutional review board (IRB) approval, an institutional cohort (2005-2015) of inpatient intra-abdominal surgery patients without preoperative AKI was identified. Data from the American College of Surgeons National Surgical Quality Improvement Program (preoperative and procedure data), Anesthesia Information Management System (intraoperative data), and electronic health record (postoperative laboratory data) were linked. The sample was split into derivation/validation (70%/30%) cohorts. AKI was defined as an increase in serum creatinine ≥0.3 mg/dL within 48 hours or >50% within 7 days of surgery. Forward logistic regression fit a baseline model incorporating preoperative variables and surgical procedure. Forward logistic regression fit a second model incorporating the previously selected baseline variables, as well as additional intraoperative variables. Intraoperative variables reflected the following aspects of intraoperative management: anesthetics, beta-blockers, blood pressure, diuretics, fluids, operative time, opioids, and vasopressors. The baseline and intraoperative models were evaluated based on statistical significance and discriminative ability (c-statistic). The risk threshold equalizing sensitivity and specificity in the intraoperative model was identified.

RESULTS

Of 2691 patients in the derivation cohort, 234 (8.7%) developed AKI. The baseline model had c-statistic 0.77 (95% confidence interval [CI], 0.74-0.80). The additional variables added to the intraoperative model were significantly associated with AKI (P < .0001) and the intraoperative model had c-statistic 0.81 (95% CI, 0.78-0.83). Sensitivity and specificity were equalized at a risk threshold of 9.0% in the intraoperative model. At this threshold, the baseline model had sensitivity and specificity of 71% (95% CI, 65-76) and 69% (95% CI, 67-70), respectively, and the intraoperative model had sensitivity and specificity of 74% (95% CI, 69-80) and 74% (95% CI, 73-76), respectively. The high-risk group had an AKI risk of 18% (95% CI, 15-20) in the baseline model and 22% (95% CI, 19-25) in the intraoperative model.

CONCLUSIONS

Intraoperative data, when added to a baseline risk prediction model for postoperative AKI in intra-abdominal surgery patients, improves the performance of the model.

Pre- and intraoperative predictors of acute kidney injury after liver transplantation

BACKGROUND

Acute kidney injury (AKI) after liver transplantation (LT) is a frequent and multifactorial event related to increased morbidity and mortality. Risk factors for AKI after LT still need to be clarified.

AIM

To identify the predictors of acute kidney injury after liver transplantation.

METHODS

The frequency and pre- and intraoperative predictors of AKI within the first 7 d after LT were evaluated in adult liver transplant candidates in a single LT center in Croatia. AKI was defined according to the Kidney Disease: Improving Global Outcomes criteria.

RESULTS

Out of 205 patients (mean age 57 ± 10 years; 73.7% males, 52.7% with alcohol-related liver disease) 93 (45.36%) developed AKI, and the majority of them (58.06%) had stage 1. Only 5.38% of patients required renal replacement therapy after LT. The majority of patients (82.8%) developed AKI within the first two days after the procedure. Multivariate logistic regression identified pre-LT body mass index (OR = 1.1, 95%CI: 1.05-1.24) and red blood cell transfusion (OR = 1.66, 95%CI: 1.09-2.53) as independent predictors of early post-LT AKI occurrence. 30-d survival after LT was significantly better for patients without AKI (P = 0.01).

CONCLUSION

Early AKI after LT is a frequent event that negatively impacts short-term survival. The pathogenesis of AKI is multifactorial, but pre-LT BMI and intraoperative volume shifts are major contributors.

Perioperative Acute Kidney Injury

Perioperative organ injury is among the leading causes of morbidity and mortality of surgical patients. Among different types of perioperative organ injury, acute kidney injury occurs particularly frequently and has an exceptionally detrimental effect on surgical outcomes. Currently, acute kidney injury is most commonly diagnosed by assessing increases in serum creatinine concentration or decreased urine output. Recently, novel biomarkers have become a focus of translational research for improving timely detection and prognosis for acute kidney injury. However, specificity and timing of biomarker release continue to present challenges to their integration into existing diagnostic regimens. Despite many clinical trials using various pharmacologic or nonpharmacologic interventions, reliable means to prevent or reverse acute kidney injury are still lacking. Nevertheless, several recent randomized multicenter trials provide new insights into renal replacement strategies, composition of intravenous fluid replacement, goal-directed fluid therapy, or remote ischemic preconditioning in their impact on perioperative acute kidney injury. This review provides an update on the latest progress toward the understanding of disease mechanism, diagnosis, and managing perioperative acute kidney injury, as well as highlights areas of ongoing research efforts for preventing and treating acute kidney injury in surgical patients.

Acute kidney injury following left ventricular assist device implantation: Contemporary insights and future perspectives

Currently, an increasing number of patients with end-stage heart failure are being treated with left ventricular assist device (LVAD) therapy as bridge-to-transplantation, bridge-to-candidacy, or destination therapy (DT). Potential life-threatening complications may occur, specifically in the early post-operative phase, which positions LVAD implantation as a high-risk surgical procedure. Acute kidney injury (AKI) is a frequently observed complication after LVAD implantation and is associated with high morbidity and mortality. The rapidly growing number of LVAD implantations necessitates better approaches of identifying high-risk patients, optimizing peri-operative management, and preventing severe complications such as AKI. This holds especially true for those patients receiving an LVAD as DT, who are typically older (with higher burden of comorbidities) with impaired renal function and at increased post-operative risk. Herein we outline the definition, diagnosis, frequency, pathophysiology, and risk factors for AKI in patients with an LVAD. We also review possible strategies to prevent and manage AKI in this patient population.

The Effect of Remote Ischemic Preconditioning on the Incidence of Acute Kidney Injury in Patients Undergoing Coronary Artery Bypass Graft Surgery: A Randomized Controlled Trial

BACKGROUND

Remote ischemic preconditioning (RIPC) protects other organs from subsequent lethal ischemic injury, but uncertainty remains. We investigated if RIPC could prevent acute kidney injury (AKI) in patients undergoing coronary artery bypass graft (CABG) surgery.

METHODS

This parallel-group, double-blind, randomized, controlled trial was done on adults undergoing elective or urgent on-pump CABG surgery from 2013 to 2017 in Shiraz, Iran. Patients were allocated to RIPC or control groups through permuted blocking. The patients in the RIPC group received three cycles of 5 min ischemia and 5 min reperfusion in the upper arm after induction of anesthesia. We placed an uninflated cuff on the arm for 30 min in the control group. The study primary endpoint was an incidence of AKI. Secondary endpoints included short-term clinical outcomes. We compared categorical and continuous variables using Pearson χ2 and unpaired t tests, respectively. P<0.05 was considered significant.

RESULTS

of the 180 patients randomized to RIPC (n=90) and control (n=90) groups, 87 patients in the RIPC and 90 patients in the control group were included in the analysis. There was no significant difference in the incidence of AKI between the groups (38 patients [43.7%] in the RIPC group and 41 patients [45.6%] in the control group; relative risk, 0.96; 95% confidence interval, 0.69 to 1.33; P=0.80). No significant differences were seen regarding secondary endpoints such as postoperative liver function, atrial fibrillation, and inpatient mortality.

CONCLUSION

RIPC did not reduce the incidence of AKI, neither did it improve short-term clinical outcomes in patients undergoing on-pump CABG surgery. Trial Registration Number: IRCT2017110537254N1.

Epidemiology of acute kidney injury and chronic kidney disease in the intensive care unit

OBJECTIVE

To describe the epidemiology of acute kidney injury, its relationship to chronic kidney disease, and the factors associated with its incidence.

METHODS

A cohort study and follow-up were conducted in an intensive care unit in Montevideo, Uruguay. We included patients admitted between November 2014 and October 2015 who were older than 15 years of age and who had at least two measurements of serum creatinine. We excluded patients who were hospitalized for less than 48 hours, patients who died at the time of hospitalization, and patients with chronic renal disease who were on hemodialysis or peritoneal dialysis. There were no interventions. Acute kidney injury was defined according to the criteria set forth in Acute Kidney Injury Disease: Improving Global Outcomes, and chronic kidney disease was defined according to the Chronic Kidney Disease Work Group.

RESULTS

We included 401 patients, 56.6% male, median age of 68 years (interquartile range (IQR) 51-79 years). The diagnosis at admission was severe sepsis 36.3%, neurocritical 16.3%, polytrauma 15.2%, and other 32.2%. The incidence of acute kidney injury was 50.1%, and 14.1% of the patients suffered from chronic kidney disease. The incidence of acute septic kidney injury was 75.3%. Mortality in patients with or without acute kidney injury was 41.8% and 14%, respectively (p < 0.001). In the multivariate analysis, the most significant variables for acute kidney injury were chronic kidney disease (odds ratio (OR) 5.39, 95%CI 2.04 - 14.29, p = 0.001), shock (OR 3.94, 95%CI 1.72 - 9.07, p = 0.001), and severe sepsis (OR 7.79, 95%CI 2.02 - 29.97, p = 0.003).

CONCLUSION

The incidence of acute kidney injury is high mainly in septic patients. Chronic kidney disease was independently associated with the development of acute kidney injury.

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.