Cardiac surgery-associated acute kidney injury: risk factors, pathophysiology and treatment

Effect of Deep Hypothermic Circulatory Arrest Versus Moderate Hypothermic Circulatory Arrest in Aortic Arch Surgery on Postoperative Renal Function: A Systematic Review and Meta-Analysis

Background

Moderate hypothermic circulatory arrest (MHCA) has been widely used in aortic arch surgery. However, the renal function after MHCA remains controversial. We performed a systematic review and meta‐analysis direct comparison of the postoperative renal function of MHCA versus deep hypothermic circulatory arrest (DHCA) in aortic arch surgery.

Methods and Results

We searched PubMed, Embase, and the Cochrane Library for postoperative renal function after aortic arch surgery with using MHCA and DHCA, published from inception to January 31, 2020. The primary outcome was renal failure. Secondary outcomes were the need for renal therapy and other major postoperative outcomes. The random‐effects model was used for all comparisons to pool the estimates. A total of 14 observational studies with 4142 patients were included. Compared with DHCA, MHCA significantly reduced the incidence of renal failure (odds ratio [OR], 0.76; 95% CI, 0.61–0.94; P=0.011; I²=0.0%) and the need of renal replacement (OR, 0.68; 95% CI, 0.48–0.97; P=0.034; I²=0.0%). Subgroup analysis showed that when the hypothermic circulatory arrest time was <30 minutes, the incidence of renal failure in MHCA group was significantly lower than that in DHCA group (OR, 0.73; 95% CI, 0.54–0.99; P=0.040; I²=1.1%), whereas an insignificant difference between 2 groups when hypothermic circulatory arrest time was >30 minutes (OR, 0.76; 95% CI, 0.51–1.13; P=0.169; I²=17.3%).

Conclusions

MHCA compared with DHCA reduces the incidence of renal failure and the need for renal replacement.

Registration

URL: https://www.crd.york.ac.uk/prospero; Unique identifier: CRD42020169348.

2020 EACTS/ELSO/STS/AATS expert consensus on post-cardiotomy extracorporeal life support in adult patients

Post-cardiotomy extracorporeal life support (PC-ECLS) in adult patients has been used only rarely but recent data have shown a remarkable increase in its use, almost certainly due to improved technology, ease of management, growing familiarity with its capability and decreased costs. Trends in worldwide in-hospital survival, however, rather than improving, have shown a decline in some experiences, likely due to increased use in more complex, critically ill patients rather than to suboptimal management. Nevertheless, PC-ECLS is proving to be a valuable resource for temporary cardiocirculatory and respiratory support in patients who would otherwise most likely die. Because a comprehensive review of PC-ECLS might be of use for the practitioner, and possibly improve patient management in this setting, the authors have attempted to create a concise, comprehensive and relevant analysis of all aspects related to PC-ECLS, with a particular emphasis on indications, technique, management and avoidance of complications, appraisal of new approaches and ethics, education and training.

Association of uromodulin with acute kidney injury in patients undergoing cardiac surgery

Uromodulin (Umod) is a protein produced exclusively in the kidneys, and it is the most abundant protein in human urine. Scientific studies show that it can be a valuable diagnostic tool in monitoring kidney function. Clinical applications of Umod are probably wider. One of them is the role of a biomarker in cardiac surgery-associated acute kidney injury (CSA-AKI). Data from scientific studies indicate that a lower level of Umod in urine prior to surgery is associated with a higher risk of developing CSA-AKI after the procedure. A higher serum Umod level is suspected to be a good prognostic factor in the context of renal healing. It seems that the current state of knowledge supports the protective role of Umod in the course of AKI. Large, multi-center clinical trials would allow for the consolidation of preliminary scientific data and a more accurate understanding of the role of Umod as a CSA-AKI biomarker.

2020 EACTS/ELSO/STS/AATS Expert Consensus on Post-Cardiotomy Extracorporeal Life Support in Adult Patients

Post-cardiotomy extracorporeal life support (PC-ECLS) in adult patients has been used only rarely but recent data have shown a remarkable increase in its use, almost certainly due to improved technology, ease of management, growing familiarity with its capability and decreased costs. Trends in worldwide in-hospital survival, however, rather than improving, have shown a decline in some experiences, likely due to increased use in more complex, critically ill patients rather than to suboptimal management. Nevertheless, PC-ECLS is proving to be a valuable resource for temporary cardiocirculatory and respiratory support in patients who would otherwise most likely die. Because a comprehensive review of PC-ECLS might be of use for the practitioner, and possibly improve patient management in this setting, the authors have attempted to create a concise, comprehensive and relevant analysis of all aspects related to PC-ECLS, with a particular emphasis on indications, technique, management and avoidance of complications, appraisal of new approaches and ethics, education and training.

Dividing Stage 1 Acute Kidney Injury After Cardiac or Thoracic Aortic Surgery

BACKGROUND

Although the Kidney Disease: Improving Global Outcomes (KDIGO) criteria are used to define acute kidney injury, the criteria have limitations for including 2 different serum creatinine criteria in stage 1. We hypothesized that there would be differences in clinical outcomes between the 2 subgroups of stage 1 acute kidney injury in patients undergoing cardiac or thoracic aortic surgery.

METHODS

We reviewed 2510 cases. Patients with KDIGO stage 1 were divided into 2 subgroups (stage 1a: 0.3 mg/dL or greater of absolute increase in serum creatinine, n = 376; and stage 1b: 50% or greater relative increase, n = 365). Propensity score analysis was performed between stage 1a and 1b groups, yielding 240 pairs. We compared the length of hospital stay, the incidence of cardiovascular complications, 5-year all-cause mortality between these subgroups. Overall survival was compared between the subgroups after propensity score matching. We performed sensitivity analysis for Acute Kidney Injury Network (AKIN) criteria.

RESULTS

Length of hospital stay and 5-year all-cause mortality were worse in patients with KDIGO stage 1b compared with stage 1a. Five-year patient survival was significantly worse in patients with stage 1b compared with stage 1a after matching (log rank test, P = .002). We found similar results regarding AKIN criteria. Subgroup analysis showed that the significant difference in survival existed only when baseline serum creatinine was 0.8 mg/dL or greater.

CONCLUSIONS

The KDIGO or AKIN criteria for stage 1 acute kidney injury could be further divided into 2 substages with different severity of clinical outcomes. These modified criteria could give additional prognostic information in patients undergoing cardiac or thoracic aortic surgery.

Changing the terminology from kidney replacement therapy to kidney support therapy

Kidney replacement therapy (KRT) is a common supportive treatment for renal dysfunction, especially acute kidney injury. However, critically ill or immunosuppressed patients with renal dysfunction often have dysfunction in other organs as well. To improve patient outcomes, clinicians began to initiate kidney replacement therapy in situations where nonrenal conditions may lead to acute kidney injury, such as septic shock, hematopoietic stem cell transplantation, veno-occlusive renal disease, cardiopulmonary bypass, chemotherapy, tumor lysis syndrome, hyperammonemia, and various others. In this review, we discuss the use of various modes of kidney replacement therapy in treating renal and nonrenal complications to illustrate why kidney support therapy is a more appropriate terminology than kidney replacement therapy.

Severe Acute Kidney Injury in Cardiovascular Surgery: Thrombotic Microangiopathy as a Differential Diagnosis to Ischemia Reperfusion Injury. A Retrospective Study

BACKGROUND

Acute kidney injury (AKI) after cardiovascular surgery (CVS) infers high morbidity and mortality and may be caused by thrombotic microangiopathy (TMA). This study aimed to assess incidence, risk factors, kidney function, and mortality of patients with a postoperative TMA as possible cause of severe AKI following cardiovascular surgery.

METHODS

We analyzed retrospectively all patients admitted to the ICU after a cardiovascular procedure between 01/2018 and 03/2019 with severe AKI and need for renal replacement therapy (RRT). TMA was defined as post-surgery-AKI including need for RRT, hemolytic anemia, and thrombocytopenia. TMA patients were compared to patients with AKI requiring RRT without TMA.

RESULTS

Out of 893 patients, 69 (7.7%) needed RRT within one week after surgery due to severe AKI. Among those, 15 (21.7%) fulfilled TMA criteria. Aortic surgery suggested an increased risk for TMA (9/15 (60.0%) vs. 7/54 (31.5%), OR 3.26, CI 1.0013-10.64). Ten TMA patients required plasmapheresis and/or eculizumab, and five recovered spontaneously. Preoperative kidney function was significantly better in TMA patients than in controls (eGFR 92 vs. 60.5 mL/min, p = 0.004). However, postoperative TMA resulted in a more pronounced GFR loss (ΔeGFR -54 vs. -17 mL/min, p = 0.062). There were no deaths in the TMA group.

CONCLUSION

Our findings suggest TMA as an important differential diagnosis of severe AKI following cardiovascular surgery, which may be triggered by aortic surgery. Therefore, early diagnosis and timely treatment of TMA could reduce kidney damage and improve mortality of AKI following cardiovascular surgery, which should be further investigated.

SOX9 promotes stress-responsive transcription of VGF nerve growth factor inducible gene in renal tubular epithelial cells

Acute kidney injury (AKI) is a common clinical condition associated with diverse etiologies and abrupt loss of renal function. In patients with sepsis, rhabdomyolysis, cancer, and cardiovascular disorders, the underlying disease or associated therapeutic interventions can cause hypoxia, cytotoxicity, and inflammatory insults to renal tubular epithelial cells (RTECs), resulting in the onset of AKI. To uncover stress-responsive disease-modifying genes, here we have carried out renal transcriptome profiling in three distinct murine models of AKI. We find that Vgf nerve growth factor inducible gene up-regulation is a common transcriptional stress response in RTECs to ischemia-, cisplatin-, and rhabdomyolysis-associated renal injury. The Vgf gene encodes a secretory peptide precursor protein that has critical neuroendocrine functions; however, its role in the kidneys remains unknown. Our functional studies show that RTEC-specific Vgf gene ablation exacerbates ischemia-, cisplatin-, and rhabdomyolysis-associated AKI in vivo and cisplatin-induced RTEC cell death in vitro Importantly, aggravation of cisplatin-induced renal injury caused by Vgf gene ablation is partly reversed by TLQP-21, a Vgf-derived peptide. Finally, in vitro and in vivo mechanistic studies showed that injury-induced Vgf up-regulation in RTECs is driven by the transcriptional regulator Sox9. These findings reveal a crucial downstream target of the Sox9-directed transcriptional program and identify Vgf as a stress-responsive protective gene in kidney tubular epithelial cells.

Prediction of Acute Kidney Injury on Admission to Pediatric Intensive Care

OBJECTIVES

Up to 37% of children admitted to the PICU develop acute kidney injury as defined by Kidney Disease: Improving Global Outcomes criteria. We describe the prevalence of acute kidney injury in a mixed pediatric intensive care cohort using this criteria. As tools to stratify patients at risk of acute kidney injury on PICU admission are lacking, we explored the variables at admission and day 1 that might predict the development of acute kidney injury.

DESIGN

Single-center retrospective observational study.

SETTING

Thirty-six-bed surgical/medical tertiary PICU.

PATIENTS

Children from birth to less than or equal to 16 years old admitted between 2015 and 2018.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Clinical data were extracted from the PICU clinical information system. Patients with baseline creatinine at admission greater than 20 micromol/L above the calculated normal creatinine level were classified as "high risk of acute kidney injury." Models were created to predict acute kidney injury at admission and on day 1. Out of the 7,505 children admitted during the study period, 738 patients (9.8%) were classified as high risk of acute kidney injury at admission and 690 (9.2%) developed acute kidney injury during PICU admission. Compared to Kidney Disease: Improving Global Outcomes criteria as the reference standard, high risk of acute kidney injury had a lower sensitivity and higher specificity compared with renal angina index greater than or equal to 8 on day 1. For the admission model, the adjusted odds ratio of developing acute kidney injury for high risk of acute kidney injury was 4.2 (95% CI, 3.3-5.2). The adjusted odds ratio in the noncardiac cohort for high risk of acute kidney injury was 7.3 (95% CI, 5.5-9.7). For the day 1 model, odds ratios for high risk of acute kidney injury and renal angina index greater than or equal to 8 were 3.3 (95% CI, 2.6-4.2) and 3.1 (95% CI, 2.4-3.8), respectively.

CONCLUSIONS

The relationship between high risk of acute kidney injury and acute kidney injury needs further evaluation. High risk of acute kidney injury performed better in the noncardiac cohort.

The Predictive Value of Urinary Kidney Injury Molecular 1 for the Diagnosis of Contrast-Induced Acute Kidney Injury after Cardiac Catheterization: A Meta-Analysis

Background

Urinary kidney injury molecule 1 (uKIM-1) is a proximal tubular injury biomarker for predicting acute kidney injury (AKI); its prognostic value varies depending on the clinical and population characteristics. However, the predictive value of uKIM-1 for diagnosis of contrast-induced acute kidney injury (CI-AKI) remains unclear.

Method

Medline, Embase, ClinicalTrials.gov, Cochrane Library database, and the China National Knowledge Infrastructure (CNKI) were used to identify relevant studies from their inception to November 31, 2019. Studies that met the inclusion criteria were included. Relevant data were extracted to obtain pooled sensitivity (SEN) and specificity (SPE), summary receiver operating characteristic curve (ROC), and area under the ROC (AUC or AUROC). A bivariate mixed-effects regression model was used for data analysis.

Results

A total of 946 patients from 8 eligible studies were included. Across all the studies, the diagnostic odds ratio (DOR) for uKIM-1 level to predict CI-AKI was 19 (95% CI 10–39), with SEN and SPE of 0.84 and 0.78, respectively. The AUROC for uKIM-1 in predicting CI-AKI was 0.88 (95% CI 0.85–0.90). There was a substantial heterogeneity across the studies (I² was 37.73% for the summary sensitivity and 69.31% for the summary specificity).

Conclusion

Urinary KIM-1 has a high predictive value for diagnosis of CI-AKI in patients who have undergone cardiac catheterization.

Risk Factors for Developing Severe Acute Kidney Injury in Adult Patients With Refractory Postcardiotomy Cardiogenic Shock Receiving Venoarterial Extracorporeal Membrane Oxygenation

OBJECTIVES

Postcardiotomy cardiogenic shock occurs in 2-6% of patients undergoing cardiac surgery, and 1% of cardiac surgery patients will require mechanical circulatory support using venoarterial extracorporeal membrane oxygenation. Acute kidney injury is a frequent complication in this population and negatively impacts the survival. We aimed to determine whether the timing of extracorporeal membrane oxygenation implantation influences the renal prognosis of these patients.

DESIGN

Retrospective observational cohort study between January 2013 and December 2016.

SETTING

An 18-bed surgical ICU in a university hospital.

PATIENTS

A total of 4,796 consecutive adult patients who underwent cardiac surgery were included in the study, and 347 (7.2%) were assisted with venoarterial extracorporeal membrane oxygenation for refractory postcardiotomy cardiogenic shock. The patients who died during the first 48 hours after venoarterial extracorporeal membrane oxygenation implantation were excluded. The complete-case analysis included 257 patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the occurrence, within 10 days following the venoarterial extracorporeal membrane oxygenation implantation, of a stage 3 acute kidney injury defined by the Kidney Disease: Improving Global Outcomes group. One hundred sixty-nine patients (65.7%) presented with a Kidney Disease: Improving Global Outcomes stage 3 acute kidney injury; 14 patients (5.4%) died before the end of the follow-up period, without developing the primary outcome. Ninety-two percent of patients with Kidney Disease: Improving Global Outcomes 3 acute kidney injury received renal replacement therapy, for a median duration of 7 days (3-16 d). Late implantation of venoarterial extracorporeal membrane oxygenation was independently associated with an increased risk of Kidney Disease: Improving Global Outcomes stage 3 acute kidney injury (odds ratio, 2.81 [95% CI, 1.31-6.07]; p = 0.008). The other factors associated with Kidney Disease: Improving Global Outcomes stage 3 acute kidney injury were preoperative left ventricular ejection fraction (odds ratio, 1.03 [95% CI, 1.01-1.05]; p = 0.007), intraoperative plasma transfusion (odds ratio, 1.13 [95% CI, 1.02-1.26]; p = 0.022), increased bilirubinemia level (odds ratio, 1.013 [95% CI, 1.001-1.026]; p = 0.032), and increased creatinine levels (odds ratio, 1.012 [95% CI, 1.006-1.018]; p < 0.001) on the day of implantation.

CONCLUSIONS

Significant kidney dysfunction is particularly frequent in patients with refractory postcardiotomy cardiogenic shock assisted with venoarterial extracorporeal membrane oxygenation. Early implantation of extracorporeal membrane oxygenation may help prevent acute kidney injury.

Effects of Preoperative Angiotensin-Converting Enzyme Inhibitor Therapy on Postoperative Renal Function in Cardiac Surgery

A Best Evidence Topic in cardiac surgery was written according to a structured protocol. The question addressed was-"In patients who undergo cardiac surgery, is preoperative angiotensin-converting enzyme inhibitor therapy associated with postoperative renal dysfunction?" Altogether, 339 papers were found using the reported search. Ten (10) were chosen which best answered the clinical question. The papers were evaluated for bias and heterogeneity using validated tools and the collected results analysed qualitatively. Evidence in the current literature is inconclusive that preoperative administration of angiotensin-converting enzyme inhibitor therapy affects postoperative renal dysfunction in patients undergoing cardiac surgery.

Prediction of the development of acute kidney injury following cardiac surgery by machine learning

Background

Cardiac surgery–associated acute kidney injury (CSA-AKI) is a major complication that results in increased morbidity and mortality after cardiac surgery. Most established prediction models are limited to the analysis of nonlinear relationships and fail to fully consider intraoperative variables, which represent the acute response to surgery. Therefore, this study utilized an artificial intelligence–based machine learning approach thorough perioperative data-driven learning to predict CSA-AKI.

Methods

A total of 671 patients undergoing cardiac surgery from August 2016 to August 2018 were enrolled. AKI following cardiac surgery was defined according to criteria from Kidney Disease: Improving Global Outcomes (KDIGO). The variables used for analysis included demographic characteristics, clinical condition, preoperative biochemistry data, preoperative medication, and intraoperative variables such as time-series hemodynamic changes. The machine learning methods used included logistic regression, support vector machine (SVM), random forest (RF), extreme gradient boosting (XGboost), and ensemble (RF + XGboost). The performance of these models was evaluated using the area under the receiver operating characteristic curve (AUC). We also utilized SHapley Additive exPlanation (SHAP) values to explain the prediction model.

Results

Development of CSA-AKI was noted in 163 patients (24.3%) during the first postoperative week. Regarding the efficacy of the single model that most accurately predicted the outcome, RF exhibited the greatest AUC (0.839, 95% confidence interval [CI] 0.772–0.898), whereas the AUC (0.843, 95% CI 0.778–0.899) of ensemble model (RF + XGboost) was even greater than that of the RF model alone. The top 3 most influential features in the RF importance matrix plot were intraoperative urine output, units of packed red blood cells (pRBCs) transfused during surgery, and preoperative hemoglobin level. The SHAP summary plot was used to illustrate the positive or negative effects of the top 20 features attributed to the RF. We also used the SHAP dependence plot to explain how a single feature affects the output of the RF prediction model.

Conclusions

In this study, machine learning methods were successfully established to predict CSA-AKI, which determines risks following cardiac surgery, enabling the optimization of postoperative treatment strategies to minimize the postoperative complications following cardiac surgeries.

Characteristics and outcomes of Stanford type A aortic dissection patients with severe post-operation hyperbilirubinemia: a retrospective cohort study

BACKGROUND

Hyperbilirubinemia is one of the common complications after cardiac surgery and is associated with increased mortality. However, to the best of our knowledge, the reports on clinical significance of postoperative severe hyperbilirubinemia in Stanford type A aortic dissection (AAD) patients were limited.

METHODS

Patients who underwent surgical treatment for AAD in our center between January 2015 and December 2018 were retrospectively screened. In-hospital mortality, long-term mortality, acute kidney injury (AKI), and the requirement of continuous renal replacement therapy (CRRT) were assessed as endpoints. Univariate and multivariate regression models were employed to identify the risk factors of these endpoints.

RESULTS

After screening, 271 patients were included in our present study. Of the included patients, 222 (81.9%) experienced postoperative AKI, and 50 (18.5%) received CRRT. The in-hospital mortality was 30.3%. The 1-year, 2-year, and 3-year cumulative mortality were 32.9, 33.9, and 35.3%, respectively. Multivariate Logistic regression analysis indicated that age (P < 0.033), AKI stage 3 (P < 0.001), the amount of blood transfusion after surgery (P = 0.019), mean arterial pressure (MAP) in the first postoperative day (P = 0.012), the use of extracorporeal membrane oxygenation (ECMO) (P = 0.02), and the peak total bilirubin (TB) concentration (P = 0.023) were independent risk factors of in-hospital mortality. The optimal cut-off value of peak TB on predicting in-hospital mortality was 121.2 μmol/L. Patients with post-operation TB ≥ 121 μmol/L was associated with worse long-term survival as well.

CONCLUSIONS

Severe post-operation hyperbilirubinemia is a common clinical situation in patients had AAD repair. In AAD patients with severe post-operation hyperbilirubinemia, older age, lower MAP, increased blood transfusion, stage 3 AKI, the use of ECMO, and the increased peak TB lead to increase in-hospital mortality.

T Cells and Acute Kidney Injury: A Two-Way Relationship

Acute Kidney Injury (AKI) complicates up to 10% of hospital admissions substantially increasing patient morbidity and mortality. Experimental evidence supports that AKI initiation and maintenance results from immune-mediated damage. Exogenous injury sources directly damage renal cells which produce pro-inflammatory mediators recruiting immune cells and furthering kidney injury. Many AKI studies focus on activation of innate immunity; major components include complement pathways, neutrophils, and monocytes. Recently, growing evidence emphasizes T lymphocytes role in affecting AKI pathogenesis and magnitude. In particular, T helper 17 lymphocytes enhance tissue injury by recruiting neutrophils and other inflammatory cells, while regulatory T cells conversely reduce renal injury and facilitate repair. Intriguingly, evidence supports local parenchymal-T cell interactions as essential to producing T cell phenotypic changes affecting long-term kidney and patient survival. Herein, we review T cells effects on AKI and patient outcomes and discuss related new therapeutic approaches to improve outcomes of affected individuals.

The predictive value of the intraoperative Renal Pulsatility Index for acute kidney injury in patients undergoing cardiac surgery

BACKGROUND

The incidence of cardiac surgery-associated acute kidney injury (CSA-AKI) is very high. The Renal Resistive Index (RRI) is measured by transesophageal echocardiography (TEE) and can be used to predict the occurrence of CSA-AKI, but few studies have examined the Renal Pulsatility Index (RPI). The objective of this study was to explore the predictive value of intraoperative RPI for CSA-AKI.

METHODS

This study was a prospective observational study. Seventy-eight patients meeting the inclusion criteria were enrolled. The RPI was measured by TEE after the induction of general anesthesia (T1) and immediately after the surgery (T2). Serum creatinine (Scr) was measured one day before and seven days after the surgery. The diagnosis of AKI was based on the KDIGO diagnostic criteria. Multivariate logistic regression analysis was used to analyze the risk factors for postoperative AKI and to draw the receiver operating characteristic curve (ROC) and analyze its diagnostic value for AKI.

RESULTS

The incidence of postoperative AKI was 29.5%. The RPI at T2 was higher in the AKI group than in the non-AKI group (2.05±0.69 versus 1.49±0.48, P<0.001). The results of multivariate analysis showed that the RPI at T2 was an independent risk factor for the occurrence of AKI (OR=4.683, 95% CI: 1.592-13.772; P=0.006). The area under the curve (AUC) of the RPI was 0.733 (95% CI: 0.621-0.827) with a cut-off value of 1.86 (sensitivity 60.87%, specificity 85.45% and Youden Index 0.46).

CONCLUSIONS

An RPI at T2>1.86 is correlated with a higher incidence of postoperative AKI. Treatment guided and personalized on the base of this parameter should be investigated by further dedicated studies.

Risk factor for acute kidney injury in patients with chronic kidney disease receiving valve surgery with cardiopulmonary bypass

INTRODUCTION

Acute kidney injury (AKI) after cardiopulmonary bypass (CPB) in patients with pre-existing impaired renal function carries deleterious outcomes but is not frequently evaluated. The optimal CPB strategy for preventing AKI in this vulnerable patient group is still controversial.

METHODS

A total of 156 patients with preoperative estimated glomerular filtration rate (e-GFR) <30 ml/min but not on chronic dialysis receiving valve operation under CPB were included in the present study. Postoperative AKI was defined as KDIGO (Kidney Disease Improving Global Outcomes) stage 3. Hospital mortality and two-year renal function evolution were compared between patients with postoperative AKI and those without AKI. Risk factors for the development of postoperative AKI were also studied.

RESULTS

The incidence of postoperative KDIGO-3 was high (44.2%). Hospital mortality was higher in the AKI group (30.4%) than in the non-AKI group (8.0%). Among the hospital survivors, renal function deterioration to permanent dialysis at two years was also more common in AKI group (14.5%) than in non-AKI group (4.6%). Univariate logistic regression for postoperative AKI revealed male gender, increased age, height, weight, BSA, and BMI, high preoperative serum creatinine, prolonged CPB duration, and decreased CPB target temperature as risk factors. However, multivariate analysis revealed only high preoperative serum creatinine and decreased CPB target temperature as significant risk factors for postoperative AKI.

CONCLUSION

To prevent postoperative AKI in CKD patients, low CPB target temperature is avoided, especially for those with high preoperative serum creatinine levels.

Proinflammatory P2Y14 receptor inhibition protects against ischemic acute kidney injury in mice

Ischemic acute kidney injury (AKI), a complication that frequently occurs in hospital settings, is often associated with hemodynamic compromise, sepsis, cardiac surgery, or exposure to nephrotoxins. Here, using a murine renal ischemia/reperfusion injury (IRI) model, we show that intercalated cells (ICs) rapidly adopted a proinflammatory phenotype after IRI. Wwe demonstrate that during the early phase of AKI either blockade of the proinflammatory P2Y14 receptor located on the apical membrane of ICs or ablation of the gene encoding the P2Y14 receptor in ICs (a) inhibited IRI-induced increase of chemokine expression in ICs, (b) reduced neutrophil and monocyte renal infiltration, (c) reduced the extent of kidney dysfunction, and (d) attenuated proximal tubule damage. These observations indicate that the P2Y14 receptor participates in the very first inflammatory steps associated with ischemic AKI. In addition, we show that the concentration of the P2Y14 receptor ligand UDP-glucose (UDP-Glc) was higher in urine samples from intensive care unit patients who developed AKI compared with patients without AKI. In particular, we observed a strong correlation between UDP-Glc concentration and the development of AKI in cardiac surgery patients. Our study identifies the UDP-Glc/P2Y14 receptor axis as a potential target for the prevention and/or attenuation of ischemic AKI.

Prerenal acute kidney injury—still a relevant term in modern clinical practice?

The traditional taxonomy of acute kidney injury (AKI) has remained pervasive in clinical nephrology. While the terms ‘prerenal’, ‘intrarenal’ and ‘postrenal’ highlight the diverse pathophysiology underlying AKI, they also imply discrete disease pathways and de-emphasize the nature of AKI as an evolving clinical syndrome with multiple, often simultaneous and overlapping, causes. In a similar vein, prerenal AKI comprises a diverse spectrum of kidney disorders, albeit one that is often managed by using a standardized clinical algorithm. We contend that the term ‘prerenal’ is too vague to adequately convey our current understanding of hypoperfusion-related AKI and that it should thus be avoided in the clinical setting. Practice patterns among nephrologists indicate that AKI-related terminology plays a significant role in the approaches that clinicians take to patients that have this complex disease. Thus, it appears that precise terminology does impact the treatment that patients receive. We will outline differences in the diagnosis and management of clinical conditions lying on the so-called prerenal disease spectrum to advocate caution when administering intravenous fluids to these clinically decompensated patients. An understanding of the underlying pathophysiology may, thus, avert clinical missteps such as fluid and vasopressor mismanagement in tenuous or critically ill patients.

Clinical and Operative Determinants of Acute Kidney Injury after Cardiac Surgery

INTRODUCTION

Cardiac surgery-associated acute kidney injury (CSA-AKI) is associated with increased morbidity and mortality.

OBJECTIVES

We aimed to identify potentially modifiable risk factors for CSA-AKI.

METHODS

This was asingle-center retrospective cohort study of 495 adult patients undergoing cardiac surgery. AKI was diagnosed and staged using full KDIGO criteria incorporating baseline serum creatinine (SC) levels and correction of postoperative SC levels for fluid balance. We examined the association of routinely available clinical and laboratory data with AKI using multivariate logistic regression modeling.

RESULTS

A total of 103 (20.8%) patients developed AKI: 16 (15.5%) patients were diagnosed with AKI upon hospital admission, and 87 (84.5%) patients were diagnosed with CSA-AKI. Correction of SC levels for fluid balance increased the number of AKI cases to 104 (21.0%), with 6 patients categorized to different AKI stages. Univariate logistic regression analysis identified five preoperative (age, sex, diabetes mellitus, preoperative systolic pulmonary arterial pressure [PSPAP], acute decompensated heart failure) and five intraoperative predictors of AKI (age, sex, red blood cell [RBC] volume transfused, use of minimally invasive surgery, duration of cardiopulmonary bypass). When all preoperative and intraoperative variables were incorporated into one model, six predictors remained significant (age, sex, use of minimally invasive surgery, RBC volume transfused, PSPAP, duration of cardiopulmonary bypass). Model discrimination performance showed an area under the curve of 0.69 for the model including only preoperative variables, 0.76 for the model including only intraoperative variables, and 0.77 for the model including all preoperative and intraoperative variables.

CONCLUSIONS

Use of minimally invasive surgery and therapies mitigating PSPAP and intraoperative blood loss may offer protection against CSA-AKI.

Predicting Acute Kidney Injury After Cardiac Surgery Using a Simpler Model

OBJECTIVE

To develop a simple model for the prediction of acute kidney injury (AKI) and renal replacement therapy (RRT) that could be used in clinical or research risk stratification.

DESIGN

Retrospective analysis.

SETTING

Multi-institutional.

PARTICIPANTS

All cardiac surgery patients from September 2016 to December 2018.

INTERVENTIONS

Observational.

MEASUREMENTS AND MAIN RESULTS

The study cohort was divided into a development set (75%) and validation set (25%). The following 2 data epochs were used: preoperative data and immediate postoperative data (within 4 h of intensive care unit admission). Univariate statistics were used to identify variables associated with AKI or RRT. Stepwise logistic regression was used to develop a parsimonious model. Model discrimination and calibration were evaluated in the test set. Models were compared with previously published models and with a more comprehensive model developed using the least absolute shrinkage and selection operator. The study included 22,731 patients at 33 hospitals. The incidences of AKI (any stage) and RRT for the present analysis were 5,829 patients (25.6%) and 488 patients (2.1%), respectively. Models were developed for AKI, with an area under the receiver operating curve (AU-ROC) of 0.67 and 0.69 preoperatively and postoperatively, respectively. Models for RRT had an AU-ROC of 0.77 and 0.80 preoperatively and postoperatively, respectively. These models contained between 3 and 5 variables. Comparatively, comprehensive least absolute shrinkage and selection operator models contained between 21 and 26 variables, with an AU-ROC of 0.71 and 0.72 for AKI and 0.84 and 0.87 for RRT respectively.

CONCLUSION

In the present study, simple, clinically applicable models for predicting AKI and RRT preoperatively and immediate postoperatively were developed. Even though AKI prediction remained poor, RRT prediction was good with a parsimonious model.

Creatinine elevations from baseline at the time of cardiac surgery are associated with postoperative complications

OBJECTIVES

Baseline kidney function is a key predictor of postoperative morbidity and mortality. Whether an increased creatinine at the time of surgery, compared with the lowest creatinine in the 3 months before surgery, is associated with poor outcomes has not been evaluated. We examined whether creatinine elevations from "baseline" were associated with adverse postoperative outcomes.

METHODS

A total of 1486 patients who underwent cardiac surgery at the University of Colorado Hospital between January 2011 and May 2016 met inclusion criteria. "Change in creatinine from baseline" was defined as the difference between the immediate presurgical creatinine value and the lowest creatinine value within 3 months preceding surgery. Outcomes evaluated were in-hospital mortality, postoperative infection, postoperative stroke, development of stage 3 acute kidney injury, intensive care unit length of stay, and hospital length of stay. Outcomes were adjusted using a balancing score to account for differences in patient characteristics.

RESULTS

There were significant increases in the odds of postoperative infection (odds ratio, 1.17; confidence interval, 1.02-1.34; per 0.1 mg/dL increase in creatinine), stage 3 acute kidney injury (odds ratio, 1.44; confidence interval; 1.18-1.75), intensive care unit length of stay (odds ratio, 1.13; confidence interval, 1.01-1.26), and hospital length of stay (odds ratio, 1.09; confidence interval, 1.05-1.13). There was a significant increase in mortality in the unadjusted analysis, although not after adjustment using a balancing score. There was no association with postoperative stroke.

CONCLUSIONS

Elevations in creatinine at the time of surgery above the "baseline" level are associated with increased postoperative morbidity. Baseline creatinine should be established before surgery, and small changes in creatinine should trigger heightened vigilance in the postoperative period.

Derivation and Validation of a Risk Prediction Model for Vancomycin-Associated Acute Kidney Injury in Chinese Population

Background

Vancomycin is the standard therapy for methicillin-resistant Staphylococcus aureus (MRSA) infection; however, nephrotoxicity happened with a high incidence of 15%~40%. Weighting the risk before receiving vancomycin treatment facilitates timely prevention of nephrotoxicity, but no standardized strategy exists for this purpose.

Methods

A retrospective cohort study was performed. A total of 524 hospitalized patients treated with vancomycin were included in this study. They were divided into derivation cohort (n=341) and externally validation cohort (n=183) according to their admission time. Using univariate and multivariable logistic regression, we identified potential predictors of vancomycin-associated acute kidney injury (AKI) and developed a risk score by plotting nomogram. The predictive performance of this novel risk score was assessed and validated by discrimination and calibration. Besides, the risk score was also compared with existing prediction models according to integrated discrimination index (IDI) and net reclassification index (NRI).

Results

The incidence of AKI was 16.1% (55/341) in the derivation cohort and 16.4% (30/183) in the validation cohort. Three factors (vancomycin serum trough concentration, piperacillin/tazobactam and furosemide) were determined as predictors for vancomycin-associated AKI. The established three-item risk score showed a comparable discrimination in both derivation cohort (AUC=0.793, 95% CI: 0.732–0.855) and validation cohort (AUC=0.788, 95% CI: 0.698–0.877). The risk score also demonstrated a good calibration in the derivation cohort (χ²=6.079, P=0.638>0.05) and validation cohort (χ²=5.665, P=0.686>0.05). Compared with prediction by C_min alone, this risk score significantly improved reclassification accuracy (IDI=0.050, 95% CI: 0.024–0.076, P<0.001, NRI=0.166, 95% CI: 0.044–0.289, P=0.007).

Conclusion

The established model in this study is a simplified three-item risk score, which provides a robust tool for the prediction of AKI after receiving vancomycin treatment.

The incidence and associations of acute kidney injury in trauma patients admitted to critical care: A systematic review and meta-analysis

BACKGROUND

As more patients are surviving the initial effects of traumatic injury clinicians are faced with managing the systemic complications of severe tissue injury. Of these, acute kidney injury (AKI) may be a sentinel complication contributing to adverse outcomes.

OBJECTIVE

To establish the incidence of AKI in patients admitted to critical care after major trauma, to explore any risk factors and to evaluate the association of AKI with outcomes.

DATA SOURCES

Systematic search of MEDLINE, Excerpta Medica database and Cochrane library from January 2004 to April 2018.

STUDY SELECTION

Studies of adult major trauma patients admitted to critical care that applied consensus AKI criteria (risk injury failure loss end stage [RIFLE], AKI network, or kidney disease improving global outcomes) and reported clinical outcomes were assessed (PROSPERO Registration: CRD42017056781). Of the 35 full-text articles selected from the screening, 17 (48.6%) studies were included.

DATA EXTRACTION AND SYNTHESIS

We followed the PRISMA guidelines and study quality was assessed using the Newcastle-Ottawa score. The pooled incidence of AKI and relative risk of death were estimated using random-effects models.

MAIN OUTCOMES AND MEASURES

Incidence of AKI was the primary outcome. The secondary outcome was study-defined mortality.

RESULTS

We included 17 articles describing AKI outcomes in 24,267 trauma patients. The pooled incidence of AKI was 20.4% (95% confidence interval [CI], 16.5-24.9). Twelve studies reported the breakdown of stages of AKI with 55.7% of patients classified as RIFLE-R or stage 1, 30.3% as RIFLE-I or stage 2, and 14.0% as RIFLE-F or stage 3. The pooled relative risk of death with AKI compared was 3.6 (95% CI, 2.4-5.3). In addition, there was a concordant increase in odds of death among six studies that adjusted for multiple variables (adjusted odds ratio, 2.7; 95% CI, 1.9-3.8; p = <0.01).

CONCLUSION

Acute kidney injury is common after major trauma and associated with increased mortality. Future research is warranted to reduce the potential for harm associated with this subtype of AKI.

LEVEL OF EVIDENCE

Systematic review and meta-analysis, level III.

Identification of risk factors for acute kidney injury after pulmonary endarterectomy with cardiopulmonary bypass

The letter to the editor made several comments on possible issues in the recent article by Zhang et al. determining the risk factors of acute kidney injury after pulmonary endarterectomy with cardiopulmonary bypass, which has been published in Journal of Cardiothoracic Surgery at December 30, 2019.

Acute kidney injury after nephron sparing surgery and microwave ablation: focus on incidence, survival impact and prediction

Purpose: To compare acute kidney injury (AKI) incidence between nephron sparing surgery (NSS) and microwave ablation (MWA) for T1a RCC patients, reveal the effect of AKI on survival prognosis, construct AKI nomogram and use Law of Total Probability for survival probability (SP) prediction.Materials and methods: Patients were studied retrospectively after NSS (n = 1267) or MWA (n = 210) from January 1, 2011 to June 30, 2017. Using one to one Propensity Score Matching (PSM), 158 pairs of patients were identified for the cohort study. AKI incidence, risk factors and impact on survival outcomes were analyzed using Chi-square test, logistic and cox regression analysis. AKI risk and SP were predicted by nomogram and Law of Total Probability. The performance of the nomogram was assessed with respect to its discrimination, calibration, and clinical usefulness.Results: AKI occurred more commonly in NSS (27.85%) cohort, when compared to MWA (17.72%) cohort (p = 0.032), but treatment modality was not independently predictive of AKI occurrence (odds ratio [OR]: 0.598; 95% confidence interval [CI]: 0.282-1.265; p = 0.178). The 5-yr overall survival (OS) was lower in AKI patients (73.5%) compared with non-AKI patients (94.8%; p < 0.001). AKI was an independent risk factor for all-cause mortality in RCC patients (hazard ratio [HR]: 2.820; 95% confidence interval [CI]: 1.110-7.165; p = 0.029). Predictors for both NSS- and MWA-related AKI included tumor diameter, baseline eGFR and CCI score. RENAL score and tumor blood supply can predict AKI after NSS and MWA, respectively. The AKI normograms demonstrated good discrimination, with AUCs >0.86, excellent calibration and net benefits at the decision curve analysis with probabilities ≥5%. SP predicted by Law of Total Probability was comparable to actual OS.Conclusion: AKI was an early indicator for poor overall survival in RCC patients. It can be predicted by several oncological parameters. Nomogram and Law of Total Probability can accurately predict AKI risk and SP.

A novel machine learning algorithm, Bayesian networks model, to predict the high-risk patients with cardiac surgery-associated acute kidney injury

BACKGROUND

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a well-recognized complication with an ominous outcome.

HYPOTHESIS

Bayesian networks (BNs) not only can reveal the complex interrelationships between predictors and CSA-AKI, but predict the individual risk of CSA-AKI occurrence.

METHODS

During 2013 and 2015, we recruited 5533 eligible participants who underwent cardiac surgery from a tertiary hospital in eastern China. Data on demographics, clinical and laboratory information were prospectively recorded in the electronic medical system and analyzed by gLASSO-logistic regression and BNs.

RESULTS

The incidences of CSA-AKI and severe CSA-AKI were 37.5% and 11.1%. BNs model revealed that gender, left ventricular ejection fractions (LVEF), serum creatinine (SCr), serum uric acid (SUA), platelet, and aortic cross-clamp time (ACCT) were found as the parent nodes of CSA-AKI, while ultrafiltration volume and postoperative central venous pressure (CVP) were connected with CSA-AKI as children nodes. In the severe CSA-AKI model, age, proteinuria, and SUA were directly linked to severe AKI; the new nodes of NYHA grade and direct bilirubin created relationships with severe AKI through was related to LVEF, surgery types, and SCr level. The internal AUCs for predicting CSA-AKI and severe AKI were 0.755 and 0.845, which remained 0.736 and 0.816 in the external validation. Given the known variables, the risk for CSA-AKI can be inferred at individual levels based on the established BNs model and prior information.

CONCLUSION

BNs model has a high accuracy, good interpretability, and strong generalizability in predicting CSA-AKI. It facilitates physicians to identify high-risk patients and implement protective strategies to improve the prognosis.

Current Status of Novel Biomarkers for the Diagnosis of Acute Kidney Injury: A Historical Perspective

Acute kidney injury (AKI) is a common and serious medical condition associated with significant increases in morbidity, mortality, and cost of care. Because of the high incidence and poor outcomes associated with AKI, there has been significant interest in the development of new therapies for the prevention and treatment of the disease. A lack of efficacy in drug trials led to the concern that AKI was not being diagnosed early enough for an effective intervention and that a rise in serum creatinine itself is not a sensitive-enough marker. Researchers have been searching for novel biomarkers that can not only assess a decline in kidney function but also demonstrate structural damage to the kidney and at time points earlier than increases in serum creatinine measurements allow. Over the past 10 years, there have been 3300 new publications and hundreds of new biomarkers investigated, yet concern still remains regarding AKI biomarker performance. The AKI biomarkers are yet to be widely utilized in clinical practice, leading some to question whether AKI biomarkers will ever reach their initial promise. However, we believe that biomarkers are an important part of current and future AKI research and clinical management. In this review, we compare the historical contexts of acute myocardial ischemia and AKI biomarker development to illustrate the progress that has been made within AKI biomarker research in a relatively short period of time and also to point out key differences between the disease processes that have been barriers to widespread AKI biomarker adoption. Finally, we discuss potential paths by which biomarkers can lead to appropriate AKI treatment responses that lower morbidity and mortality.

The Impact of Anesthetic Regimen on Outcomes in Adult Cardiac Surgery: A Narrative Review

Despite improvements in surgical techniques and perioperative care, cardiac surgery still is burdened by relatively high mortality and frequent major postoperative complications, including myocardial dysfunction, pulmonary complications, neurologic injury, and acute kidney injury. Although the surgeon's skills and volume and patient- and procedure-related risk factors play a major role in the success of cardiac surgery, there is growing evidence that also optimizing perioperative care may improve outcomes significantly. The present review focuses on the aspects of perioperative care that are strictly related to the anesthesia regimen, with special reference to volatile anesthetics and neuraxial anesthesia, whose effect on outcome in adult cardiac surgery has been investigated extensively.

The Clinical Course of Acute Kidney Disease after Cardiac Surgery: A Retrospective Observational Study

Acute kidney disease (AKD), or renal dysfunction persisting >7 days after an initiating event of acute kidney injury, is a rising concern. This study aimed to elucidate the clinical course of AKD after cardiac surgery with data on post-cardiac surgery patients admitted to intensive care units (ICU) at 18 Japanese hospitals during 2012–2014. Using multivariable logistic models, we evaluated the association of AKD with 90-day mortality and the 50% eGFR decline during 2-year follow-up compared to eGFR at 90 days. AKD was defined as an elevation in serum creatinine to at least 1.5-fold from baseline in >7 days after ICU admission. Of the 3,605 eligible patients undergoing cardiac surgery, 403 patients (11.2%) had AKD. Multivariable analysis revealed that the adjusted odds ratio (OR) of AKD for 90-day mortality was 63.0 (95% confidence interval [CI], 27.9–180.6). In addition, the adjusted OR of AKD for 50% eGFR decline was 3.56 (95% CI, 2.24–5.57) among hospital survivors. In conclusion, AKD after cardiac surgery was associated with higher 90-day mortality and renal function decline after hospital discharge.

Probing renal blood volume with magnetic resonance imaging

Damage to the kidney substantially reduces life expectancy. Renal tissue hypoperfusion and hypoxia are key elements in the pathophysiology of acute kidney injury and its progression to chronic kidney disease. In vivo assessment of renal haemodynamics and tissue oxygenation remains a challenge. Blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) is sensitive to changes in the effective transversal relaxation time (T₂ *) in vivo, and is non-invasive and indicative of renal tissue oxygenation. However, the renal T₂ * to tissue pO₂ relationship is not governed exclusively by renal blood oxygenation, but is affected by physiological confounders with alterations in renal blood volume fraction (BVf) being of particular relevance. To decipher this interference probing renal BVf is essential for the pursuit of renal MR oximetry. Superparamagnetic iron oxide nanoparticle (USPIO) preparations can be used as MRI visible blood pool markers for detailing alterations in BVf. This review promotes the opportunities of MRI-based assessment of renal BVf. Following an outline on the specifics of renal oxygenation and perfusion, changes in renal BVf upon interventions and their potential impact on renal T₂ * are discussed. We also describe the basic principles of renal BVf assessment using ferumoxytol-enhanced MRI in the equilibrium concentration regimen. We demonstrate that ferumoxytol does not alter control of renal haemodynamics and oxygenation. Preclinical applications of ferumoxytol enhanced renal MRI as well as considerations for its clinical implementation for examining renal BVf changes are provided alongside practical considerations. Finally, we explore the future directions of MRI-based assessment of renal BVf.

Ribociclib mitigates cisplatin-associated kidney injury through retinoblastoma-1 dependent mechanisms

Aberrant cell cycle activation is a hallmark of carcinogenesis. Recently three cell cycle targeting cyclin-dependent kinase 4/6 (CDK4/6) inhibitors have been approved for the treatment of metastatic breast cancer. CDK4/6 inhibitors suppress proliferation through inhibition of CDK4/6-dependent retinoblastoma-1 (Rb1) phosphorylation and inactivation, a key regulatory step in G1-to-S-phase transition. Importantly, aberrant cell cycle activation is also linked with several non-oncological diseases including acute kidney injury (AKI). AKI is a common disorder caused by toxic, inflammatory, and ischemic damage to renal tubular epithelial cells (RTECs). Interestingly, AKI triggered by the anti-cancer drug cisplatin can be mitigated by ribociclib, a CDK4/6 inhibitor, through mechanisms that remain unclear. Employing in vivo cell cycle analysis and functional Rb1 knock-down, here, we have examined the cellular and pharmacological basis of the renal protective effects of ribociclib during cisplatin nephrotoxicity. Remarkably, siRNA-mediated Rb1 silencing or RTEC-specific Rb1 gene ablation did not alter the severity of cisplatin-associated AKI; however, it completely abrogated the protective effects conferred by ribociclib administration. Furthermore, we find that cisplatin treatment evokes CDK4/6 activation and Rb1 phosphorylation in the normally quiescent RTECs, however, this is not followed by S-phase entry likely due to DNA-damage induced G1 arrest. The cytoprotective effects of ribociclib are thus not a result of suppression of S-phase entry but are likely dependent on the maintenance of Rb1 in a hypo-phosphorylated and functionally active form under stress conditions. These findings delineate the role of Rb1 in AKI and illustrate the pharmacological basis of the renal protective effects of CDK4/6 inhibitors.

Risk Factors for Acute Kidney Injury in Hospitalized Non-Critically Ill Patients: A Population-Based Study

OBJECTIVE

To develop and validate an acute kidney injury (AKI) risk prediction model for hospitalized non-critically ill patients.

PATIENTS AND METHODS

We retrospectively identified all Olmsted County, Minnesota, residents admitted to non-intensive care unit (ICU) wards at Mayo Clinic Hospital, Rochester, Minnesota, in 2013 and 2014. The cohort was divided into development and validation sets by year. The primary outcome was hospital-acquired AKI defined by Kidney Disease: Improving Global Outcomes criteria. Cox regression was used to analyze mortality data. Comorbid risk factors for AKI were identified, and a multivariable model was developed and validated.

RESULTS

The development and validation cohorts included 3816 and 3232 adults, respectively. Approximately 10% of patients in both cohorts had AKI, and patients with AKI had an increased risk of death (hazard ratio, 3.62; 95% CI, 2.97-4.43; P<.001). Significant univariate determinants of AKI were preexisting kidney disease, diabetes mellitus, hypertension, heart failure, vascular disease, coagulopathy, pulmonary disease, coronary artery disease, cancer, obesity, liver disease, and weight loss (all P<.05). The final multivariable model included increased baseline serum creatinine value, admission to a medical service, pulmonary disease, diabetes mellitus, kidney disease, cancer, hypertension, and vascular disease. The area under the receiver operating characteristic curves for the development and validation cohorts were 0.71 (95% CI, 0.69-0.75) and 0.75 (95% CI, 0.72-0.78), respectively.

CONCLUSION

Hospital-acquired AKI is common in non-ICU inpatients and is associated with worse outcomes. Patient data at admission can be used to identify increased risk; such patients may benefit from more intensive monitoring and earlier intervention and testing with emerging biomarkers.

Predictive role of estimated glomerular filtration rate prior to surgery in postsurgical acute kidney injury among very elderly patients: a retrospective cohort study

Background: Acute kidney injury (AKI) is a common complication after surgery. Because of unpredictable and variable age-dependent physical decline, the incidence, risk factor of postsurgical AKI and the predictive power of estimated glomerular filtration rate prior to surgery (eGFRpreSurg) has not been fully elucidated in very elderly patients.

Methods: All discharged patients aged ≥80 years without chronic kidney disease who underwent surgery prior to intensive care unit (ICU) admission from 2017 through 2018 were included. Clinical, biological and surgical data were recorded. Mean of outpatient creatinine values from the year prior to ICU admission was used as the baseline value to determine the occurrence of AKI. Postoperative AKI was diagnosed according to Kidney Disease Improving Global Outcomes criteria.

Results: Among 243 very elderly postoperative patients admitted during the study period, 48 had AKI during their ICU stay. The occurrence of postsurgical AKI was associated with longer ventilation times (p < .001) and higher mortality (p < .001). The eGFRpreSurg, which is calculated based on the Modification of Diet in Renal Disease study equation, was a risk factor for postoperative AKI (OR = 2.662, p = .010). The incidence of postoperative AKI was significantly higher among patients with lower eGFRpreSurg than among those with an eGFRpreSurg ≥ 70 mL/min/1.73 m² (p = .003).

Conclusion: Postsurgical AKI in very elderly patients has a high incidence and is a risk factor for mortality. Our study confirmed that eGFRpreSurg could be used as an index for AKI risk stratification.

Soluble Urokinase Receptor and Acute Kidney Injury

BACKGROUND

Acute kidney injury is common, with a major effect on morbidity and health care utilization. Soluble urokinase plasminogen activator receptor (suPAR) is a signaling glycoprotein thought to be involved in the pathogenesis of kidney disease. We investigated whether a high level of suPAR predisposed patients to acute kidney injury in multiple clinical contexts, and we used experimental models to identify mechanisms by which suPAR acts and to assess it as a therapeutic target.

METHODS

We measured plasma levels of suPAR preprocedurally in patients who underwent coronary angiography and patients who underwent cardiac surgery and at the time of admission to the intensive care unit in critically ill patients. We assessed the risk of acute kidney injury at 7 days as the primary outcome and acute kidney injury or death at 90 days as a secondary outcome, according to quartile of suPAR level. In experimental studies, we used a monoclonal antibody to urokinase plasminogen activator receptor (uPAR) as a therapeutic strategy to attenuate acute kidney injury in transgenic mice receiving contrast material. We also assessed cellular bioenergetics and generation of reactive oxygen species in human kidney proximal tubular (HK-2) cells that were exposed to recombinant suPAR.

RESULTS

The suPAR level was assessed in 3827 patients who were undergoing coronary angiography, 250 who were undergoing cardiac surgery, and 692 who were critically ill. Acute kidney injury developed in 318 patients (8%) who had undergone coronary angiography. The highest suPAR quartile (vs. the lowest) had an adjusted odds ratio of 2.66 (95% confidence interval [CI], 1.77 to 3.99) for acute kidney injury and 2.29 (95% CI, 1.71 to 3.06) for acute kidney injury or death at 90 days. Findings were similar in the surgical and critically ill cohorts. The suPAR-overexpressing mice that were given contrast material had greater functional and histologic evidence of acute kidney injury than wild-type mice. The suPAR-treated HK-2 cells showed heightened energetic demand and mitochondrial superoxide generation. Pretreatment with a uPAR monoclonal antibody attenuated kidney injury in suPAR-overexpressing mice and normalized bioenergetic changes in HK-2 cells.

CONCLUSIONS

High suPAR levels were associated with acute kidney injury in various clinical and experimental contexts. (Funded by the National Institutes of Health and others.).

Remote Ischemic Preconditioning Prevents Postoperative Acute Kidney Injury After Open Total Aortic Arch Replacement: A Double-Blind, Randomized, Sham-Controlled Trial

BACKGROUND

Acute kidney injury is a common complication after open total aortic arch replacement but lacks effective preventive strategies. Remote ischemic preconditioning has controversial results of its benefit to the kidney and may perform better in high-risk patients of acute kidney injury. We investigated whether remote ischemic preconditioning would prevent postoperative acute kidney injury after open total aortic arch replacement.

METHODS

We enrolled 130 patients scheduled for open total aortic arch replacement and randomized them to receive either remote ischemic preconditioning (4 cycles of 5-minute right upper limb ischemia and 5-minute reperfusion) or sham preconditioning (4 cycles of 5-minute right upper limb pseudo ischemia and 5-minute reperfusion), both via blood pressure cuff inflation and deflation. The primary end point was the incidence of acute kidney injury within 7 days after the surgery defined by the Kidney Disease: Improving Global Outcomes criteria. Secondary end point included short-term clinical outcomes.

RESULTS

Significantly fewer patients developed postoperative acute kidney injury with remote ischemic preconditioning compared with sham (55.4% vs 73.8%; absolute risk reduction, 18.5%; 95% CI, 2.3%-34.6%; P = .028). Remote ischemic preconditioning significantly reduced acute kidney injury stage II-III (10.8% vs 35.4%; P = .001). Remote ischemic preconditioning shortened the mechanical ventilation duration (18 hours [interquartile range, 14-33] versus 25 hours [interquartile range, 17-48]; P = .01), whereas no significant differences were observed between groups in other secondary outcomes.

CONCLUSIONS

Remote ischemic preconditioning prevented acute kidney injury after open total aortic arch replacement, especially severe acute kidney injury and shortened mechanical ventilation duration. The observed renoprotective effects of remote ischemic preconditioning require further investigation in both clinical research and the underlying mechanism.

The Association Between Obesity and Risk of Acute Kidney Injury After Cardiac Surgery

OBJECTIVE

To determine the relationship between obesity and the risk of AKI after cardiac surgery (CS-AKI) in a cohort study.

METHODS

A total of 1,601 patients undergoing cardiac surgery were collected and their incidence of CS-AKI was recorded. They were divided into underweight, normal weight, overweight, and obese groups. Logistic regression was used to estimate the association between BMI (body mass index) and CS-AKI risk. Then, a meta-analysis of published cohort studies was conducted to confirm this result using PubMed and Embase databases.

RESULTS

A significant association was observed in this independent cohort after adjusting age, gender, hypertension and New York Heart Association classification (NYHA) class. Compared with normal BMI group (18.5 ≤ BMI < 24.0), the individuals with aberrant BMI level had an increased AKI risk (OR: 1.68, 95% CI: 1.01-2.78) for BMI < 18.5 group and (OR: 1.43, 95% CI: 0.96-2.15) for BMI ≥ 28.0. Interestingly, the U-shape curve showed the CS-AKI risk reduced with the increasing of BMI when BMI ≤ 24.0. As BMI increases with BMI > 24.0, the risk of developing CS-AKI increased significantly. In the confirmed meta-analysis, compared with normal weight, overweight group with cardiac surgery had higher AKI risk (OR: 1.28, 95% CI: 1.16-1.41, P_{heterogeneity} = 0.49). The similar association was found in obesity subgroup (OR: 1.79, 95% CI: 1.57-2.03, P_{heterogeneity} = 0.42).

CONCLUSION

In conclusion, the results suggested that abnormal BMI was a risk factor for CS-AKI independently.

Preoperative platelet count, preoperative hemoglobin concentration and deep hypothermic circulatory arrest duration are risk factors for acute kidney injury after pulmonary endarterectomy: a retrospective cohort study

Background

Acute kidney injury (AKI) is a major postoperative morbidity of patients undergoing cardiac surgery and has a negative effect on prognosis. The kidney outcomes after pulmonary endarterectomy (PEA) have not yet been reported; However, several perioperative characteristics of PEA may induce postoperative AKI. The objective of our study was to identify the incidence and risk factors for postoperative AKI and its association with short-term outcomes.

Methods

This was a single-center, retrospective, observational, cohort study. Assessments of AKI diagnosis was executed based on the Kidney Disease Improving Global Outcomes (KDIGO) criteria.

Results

A total of 123 consecutive patients who underwent PEA between 2014 and 2018 were included.

The incidence of postoperative AKI was 45% in the study population. Stage 3 AKI was associated with worse short-term outcomes and 90-day mortality (p < 0.001, p = 0.002, respectively). The independent predictors of postoperative AKI were the preoperative platelet count (OR 0.992; 95%CI 0.984–0.999; P = 0.022), preoperative hemoglobin concentration (OR 0.969; 95%CI 0.946–0.993; P = 0.01) and deep hypothermic circulatory arrest (DHCA) time (OR 1.197; 95%CI 1.052–1.362; P = 0.006) in the multivariate analysis.

Conclusion

The incidence of postoperative AKI was relatively high after PEA compared with other types of cardiothoracic surgeries. The preoperative platelet count, preoperative hemoglobin concentration and DHCA duration were modifiable predictors of AKI, and patients may benefit from some low-risk, low-cost perioperative measures.

Impacto do controle glicêmico intensivo na lesão renal aguda: ensaio clínico randomizado

Resumo Objetivo Avaliar o impacto do controle glicêmico intensivo na redução da incidência de lesão renal aguda em pacientes adultos submetidos à cirurgia cardíaca. Métodos Ensaio clínico randomizado que avaliou 95 pacientes submetidos a duas estratégias de controle glicêmico. Os pacientes foram randomizados para o grupo intervenção (GI), com a meta de manutenção da glicemia pós-operatória entre 90 e 110 mg/dl. Nos pacientes alocados no grupo convencional (GC) o objetivo era a manutenção da glicemia entre 140 e 180 mg/dl. O ajuste da dose de insulina foi baseado em medições de glicose no sangue arterial não diluído, em intervalos de uma hora por meio de um sistema de monitoramento de glicose e beta-cetona no sangue. Resultados A incidência de LRA foi de 53,7% (KDIGO estágios 1, 2 ou 3). Não houve diferença significante entre os grupos quanto ao desfecho primário (p=0,294). Entretanto, observou-se maior frequência de recuperação da função renal (p=0,010), na alta da UTI (p=0,028) e alta hospitalar (p=0,048) entre os pacientes submetidos ao controle glicêmico convencional. A utilização do controle glicêmico intensivo esteve associada com maior tempo de permanência na UTI (p=0,031). O número de episódios de hipoglicemia foi semelhante nos dois grupos (1,6 ± 0,9 vs. 1,3 ± 0,6, p=0,731), demonstrando a segurança das estratégias utilizadas. Conclusão Não se observou o impacto do controle glicêmico intensivo na redução da incidência de lesão renal aguda. Em contrapartida, os pacientes tratados no GC apresentaram maior frequência de recuperação da função renal.