Cardiac surgery-associated acute kidney injury

Intraoperative hyperglycemia in patients with an elevated preoperative C-reactive protein level may increase the risk of acute kidney injury after cardiac surgery

PURPOSE

The effect of hyperglycemia on acute kidney injury (AKI) in patients undergoing cardiac surgery is unclear and may involve as yet unexplored factors. We hypothesized differential effects of intraoperative hyperglycemia on AKI after cardiac surgery depending on baseline inflammatory status, as reflected by the C-reactive protein (CRP) level.

METHODS

This retrospective study included patients who underwent cardiac surgery seen at our hospital from 2008 to 2018. Patients were classified into four groups according to their preoperative CRP level (≥ 1 or < 1 mg/dl) and their intraoperative time-weighted average glucose concentration (> 140 or ≤ 140 mg/dl): low CRP and normoglycemia, low CRP and hyperglycemia, high CRP and normoglycemia, and high CRP and hyperglycemia. The data were analyzed by multivariable logistic regression analysis.

RESULTS

The data of 3625 patients were analyzed. The logistic regression showed that patients in the high CRP and hyperglycemia group had a significantly higher risk of AKI than patients in the low CRP and normoglycemia group [odds ratio (OR), 1.58; 95% confidence interval (CI) 1.10-2.27], low CRP with hyperglycemia group (OR, 1.69; 95% CI 1.16-2.47) and high CRP with normoglycemia group (OR, 1.50; 95% CI 1.01-2.23).

CONCLUSIONS

Intraoperative hyperglycemia in patients with an elevated preoperative CRP level was significantly related to an increased risk of AKI after cardiac surgery. Individualized perioperative glycemic control may therefore be necessary in these patients.

Preoperative C-reactive protein as a predictor of postoperative acute kidney injury in patients undergoing coronary artery bypass grafting

C-reactive protein is a well-known marker of inflammation and may be preoperatively elevated in the absence of infection in adult cardiac surgery patients, indicating a baseline inflammatory process. We conducted a literature search to assess the available evidence on whether there is an association between preoperative C-reactive protein and acute kidney injury after coronary artery bypass grafting. Included only were observational studies which investigated this association. We excluded abstracts, case reports, animal studies and articles in languages other than English. Altogether, 199 papers were retrieved from the search strategy reported, of which 6 studies were included in the final review. The study types, publication details, patient groups and key results are tabulated. A qualitative assessment of these papers was conducted. We conclude that there is some evidence to support the association between high preoperative C-reactive protein level and postoperative acute kidney injury and complications after coronary artery bypass grafting. Owing to variability in acute kidney injury definitions and C-reactive protein levels for different cohorts in the observational studies reviewed, it is unclear from current evidence what serum C-reactive protein cut-off level is significantly associated with postoperative acute kidney injury. Further evidence is needed to investigate whether raised preoperative C-reactive protein in the absence of an infective cause could have a role in risk prediction models for cardiac surgery-associated 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.

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.

Does Fenoldopam Protect Kidney in Cardiac Surgery? A Systemic Review and Meta-Analysis With Trial Sequential Analysis

PURPOSE

To assess the benefits and harms of fenoldopam for nephroprotective effects in adult patients undergoing cardiac surgery.

METHODS

We conducted a systematic review with meta-analysis of randomized controlled trials (RCTs) comparing fenoldopam with placebo in cardiac surgery. Trials were systematically searched from PubMed, EMBASE, CENTRAL, and CNKI databases, up to July 30, 2018. A trial sequential analysis (TSA) was used to determine whether the present evidence was valid and conclusive for the primary outcomes.

RESULTS

A total of seven randomized controlled trials involving 1,107 adult patients undergoing cardiac surgery fulfilled the inclusion criteria. The pooled analysis suggested that the use of fenoldopam was associated with a reduction in the incidence of AKI (18 of 216 [8.3%] in the fenoldopam group versus 45 of 222 [20.3%] in the placebo group, RR = 0.42 [0.26, 0.69], P = 0.0006) and with a higher rate of hypotension (92/357 [25.8%] versus 51/348 [14.7%], RR = 1.76 [1.29, 2.39], P = 0.0003). There was no significant effect on renal replacement therapy requirement (77 of 540 [14.3%] versus 75 of 536 [14.0%], P = 0.96) or hospital mortality (87/392 [22.2%] versus 83/383 [21.7%], P = 0.86). TSA supported the results of the conventional analysis on AKI.

CONCLUSIONS

Low-dose dopamine offers transient improvements in renal physiology, but no good evidence shows that it offers important clinical benefits to patients with or at risk for acute renal failure.Among patients treated with fenoldopam, there was a decrease in AKI and an increased incidence of hypotension, had no significant effect on RRT or mortality. Given that most studies were small and the definition of AKI was variable between studies, there is not enough evidence to support the systematic use of fenoldopam in cardiac surgery.

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.

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.

The Impact of Perioperative Use of a Statin-Magnesium Combination on Opioid Consumption in Patients Who Underwent Cardiac Surgery: A Retrospective Study with Propensity-Score Matching

Both statins and magnesium are associated with NMDA receptors and anti-inflammatory effect. Peripheral NMDA receptors are known to be involved in inflammation-induced pain. This study aimed to investigate the impact of perioperative use of a statin–magnesium combination on opioid consumption in patients who underwent cardiac surgery. This was a retrospective study of 542 patients who underwent cardiac surgery. The patients were divided into two groups according to statin use: the statin–magnesium group (n=375) and the magnesium-only group (n=167). Patients in the magnesium-only group received only perioperative magnesium, but no statins, to prevent atrial fibrillation following cardiac surgery. After propensity-score matching, 228 patients (n=114 in each group) were analyzed to investigate opioid consumption, visual analogue scale (VAS) pain scores over a 72-h period, and pain outcomes according to the duration of statin treatment (<1 or ≥1 yr). The consumed opioid volume was significantly smaller in statin–magnesium group than the magnesium-only group, both before (p=0.010) and after matching (p=0.017). The statin–magnesium combination did not significantly reduce the VAS pain scores compared with magnesium alone. Although the statin–magnesium combination did not significantly reduce the pain intensity compared with magnesium alone, the combination therapy was effective in reducing opioid consumption after surgery.

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.

Association of pre-operative chronic kidney disease and acute kidney injury with in-hospital outcomes of emergency colorectal surgery: a cohort study

BACKGROUND

Pre-operative kidney function is known to be associated with surgical outcomes. However, in emergency surgery, the pre-operative kidney function may reflect chronic kidney disease (CKD) or acute kidney injury (AKI). We examined the association of pre-operative CKD and/or AKI with in-hospital outcomes of emergency colorectal surgery.

METHODS

We conducted a retrospective cohort study including adult patients undergoing emergency colorectal surgery in 38 Japanese hospitals between 2010 and 2017. We classified patients into five groups according to the pre-operative status of CKD (defined as baseline estimated glomerular filtration rate < 60 mL/min/1.73 m2 or recorded diagnosis of CKD), AKI (defined as admission serum creatinine value/baseline serum creatinine value ≥ 1.5), and end-stage renal disease (ESRD): (i) CKD(-)AKI(-), (ii) CKD(-)AKI(+), (iii) CKD(+)AKI(-), (iv) CKD(+)AKI(+), and (v) ESRD groups. The primary outcome was in-hospital mortality, while secondary outcomes included use of vasoactive drugs, mechanical ventilation, blood transfusion, post-operative renal replacement therapy, and length of hospital stay. We compared these outcomes among the five groups, followed by a multivariable logistic regression analysis for in-hospital mortality.

RESULTS

We identified 3002 patients with emergency colorectal surgery (mean age 70.3 ± 15.4 years, male 54.5%). The in-hospital mortality was 8.6% (169/1963), 23.8% (129/541), 15.3% (52/340), 28.8% (17/59), and 32.3% (32/99) for CKD(-)AKI(-), CKD(-)AKI(+), CKD(+)AKI(-), CKD(+)AKI(+), and ESRD, respectively. Other outcomes such as blood transfusion and post-operative renal replacement therapy showed similar trends. Compared to the CKD(-)AKI(-) group, the adjusted odds ratio (95% confidence interval) for in-hospital mortality was 2.54 (1.90-3.40), 1.29 (0.90-1.85), 2.86 (1.54-5.32), and 2.76 (1.55-4.93) for CKD(-)AKI(+), CKD(+)AKI(-), CKD(+)AKI(+), and ESRD groups, respectively. Stratified by baseline eGFR (> 90, 60-89, 30-59, and < 30 mL/min/1.73 m2) and AKI status, the crude in-hospital mortality and adjusted odds ratio increased in patients with baseline eGFR < 30 mL/min/1.73 m2 among patients without AKI, while these were constantly high regardless of baseline eGFR among patients with AKI. Additional analysis restricting to 2162 patients receiving the surgery on the day of hospital admission showed similar results.

CONCLUSIONS

The differentiation of pre-operative CKD and AKI, especially the identification of AKI, is useful for risk stratification in patients undergoing emergency colorectal surgery.

Risk estimation model for acute kidney injury defined by KDIGO classification after heart valve replacement surgery

OBJECTIVES

Risk prediction for postoperative acute kidney injury (AKI) has a great clinical value to achieve early prevention strategies for AKI after cardiac surgery. We aimed to identify the patients at risk of postoperative AKI and to create patient risk group for AKI using a simple risk estimation model in patients undergoing heart valve replacement surgery.

METHODS

Between May 2008 and February 2018, 219 consecutive patients undergoing heart valve replacement surgery with or without concomitant coronary artery bypass grafting (CAGB) were included in the study. To define postoperative AKI and its severity stages, KDIGO classification which is the latest uniform classification for determining and staging of AKI was used.

RESULTS

The AKI incidence was 38.8%, and Class I was the dominant stage (43.5%). Postoperative AKI development was associated with a serious of postoperative adverse events, early, and long-term mortality. Furthermore, the incidence of poor outcomes increased with the degree of AKI severity. The presence of older age, chronic obstructive pulmonary disease, NYHA class III-IV, diabetes, concomitant CABG, and longer cardiopulmonary bypass duration was found to be an independent predictor for AKI, and each factor was scored according to the integer value of their odds ratio, based on risk estimation model. Patient risk groups from mild to severe for AKI development were created. The patients at severe risk group exhibited a significantly higher rate of adverse events, early, and long-term mortality as well as lower long-term survival rates.

CONCLUSIONS

The risk estimation model is a useful tool to identify the patients at risk and to create patient risk groups for postoperative AKI defined by KDIGO after heart valve replacement surgery.

Near-Infrared Spectroscopy Monitoring in Cardiac and Noncardiac Surgery: Pairwise and Network Meta-Analyses

Goal-directed therapy based on brain-oxygen saturation (bSo2) is controversial and hotly debated. While meta-analyses of aggregated data have shown no clinical benefit for brain near-infrared spectroscopy (NIRS)-based interventions after cardiac surgery, no network meta-analyses involving both major cardiac and noncardiac procedures have yet been undertaken. Randomized controlled trials involving NIRS monitoring in both major cardiac and noncardiac surgery were included. Aggregate-level data summary estimates of critical outcomes (postoperative cognitive decline (POCD)/postoperative delirium (POD), acute kidney injury, cardiovascular events, bleeding/need for transfusion, and postoperative mortality) were obtained. NIRS was only associated with protection against POCD/POD in cardiac surgery patients (pooled odds ratio (OR)/95% confidence interval (CI)/I2/number of studies (n): 0.34/0.14-0.85/75%/7), although a favorable effect was observed in the analysis, including both cardiac and noncardiac procedures. However, the benefit of the use of NIRS monitoring was undetectable in Bayesian network meta-analysis, although maintaining bSo2 > 80% of the baseline appeared to have the most pronounced impact. Evidence was imprecise regarding acute kidney injury, cardiovascular events, bleeding/need for transfusion, and postoperative mortality. There is evidence that brain NIRS-based algorithms are effective in preventing POCD/POD in cardiac surgery, but not in major noncardiac surgery. However, the specific target bSo2 threshold has yet to be determined.

Stage 1 acute kidney injury is independently associated with infection following cardiac surgery

OBJECTIVES

Severe acute kidney injury (AKI) is a known risk factor for infection and mortality. However, whether stage 1 AKI is a risk factor for infection has not been evaluated in adults. We hypothesized that stage 1 AKI following cardiac surgery would independently associate with infection and mortality.

METHODS

In this retrospective propensity score-matched study, we evaluated 1620 adult patients who underwent nonemergent cardiac surgery at the University of Colorado Hospital from 2011 to 2017. Patients who developed stage 1 AKI by Kidney Disease Improving Global Outcomes creatinine criteria within 72 hours of surgery were matched to patients who did not develop AKI. The primary outcome was an infection, defined as a new surgical-site infection, positive blood or urine culture, or development of pneumonia. Secondary outcomes included in-hospital mortality, stroke, and intensive care unit (ICU) and hospital length of stay (LOS).

RESULTS

Stage 1 AKI occurred in 293 patients (18.3%). Infection occurred in 20.9% of patients with stage 1 AKI compared with 8.1% in the no-AKI group (P < .001). In propensity-score matched analysis, stage 1 AKI independently associated with increased infection (odds ratio [OR]; 2.24, 95% confidence interval [CI], 1.37-3.17), ICU LOS (OR, 2.38; 95% CI, 1.71-3.31), and hospital LOS (OR, 1.30; 95% CI, 1.17-1.45).

CONCLUSIONS

Stage 1 AKI is independently associated with postoperative infection, ICU LOS, and hospital LOS. Treatment strategies focused on prevention, early recognition, and optimal medical management of AKI may decrease significant postoperative morbidity.

The Overlooked Immune State in Candidemia: A Risk Factor for Mortality

Lymphopenia has been related to increased mortality in septic patients. Nonetheless, the impact of lymphocyte count on candidemia mortality and prognosis has not been addressed. We conducted a retrospective study, including all admitted patients with candidemia from 2007 to 2016. We examined lymphocyte counts during the first 5 days following the diagnosis of candidemia. Multivariable logistic regression analysis was performed to determine the relationship between lymphocyte count and mortality. Classification and Regression Tree analysis was used to identify the best cut-off of lymphocyte count for mortality associated with candidemia. From 296 cases of candidemia, 115 died, (39.8% 30-day mortality). Low lymphocyte count was related to mortality and poor outcome (p < 0.001). Lymphocyte counts <0.703 × 10⁹ cells/L at diagnosis (area under the curve (AUC)-ROC, 0.783 ± 0.042; 95% confidence interval (CI), 0.700-0.867, p < 0.001), and lymphocyte count <1.272 × 10⁹ cells/L five days later (AUC-ROC, 0.791 ± 0.038; 95%CI, 0.716-0.866, p < 0.001) increased the odds of mortality five-fold (odds ratio (OR), 5.01; 95%CI, 2.39-10.93) at time of diagnosis, and three-fold (OR, 3.27; 95%CI, 1.24-8.62) by day 5, respectively. Low lymphocyte count is an independent predictor of mortality in patients with candidemia and might serve as a biomarker for predicting candidemia-associated mortality and poor outcome.

Biomarkers of Acute Kidney Injury after Cardiac Surgery: A Narrative Review

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a major and serious complication in patients undergoing cardiac surgery and is independently associated with perioperative mortality and mortality. Therapeutic intervention aiming at reversing kidney dysfunction seems disappointing across multiple settings. Consequently, attention has shifted from treatment to prevention and early detection. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines have unified diagnostic standards mainly based on the serum creatinine (Scr) level or urine output, but neither marker is kidney specific. Efforts have been made to identify novel biomarkers with high sensitivity and specificity. The diagnostic capabilities of neutrophil gelatinase-associated lipocalin (NGAL) and G1 cell cycle arrest biomarker as biomarkers have been confirmed in a large number of clinical trials. The utility of biomarkers of cardiac function and inflammation has been validated in clinical studies. Aiming to offer valuable information for further research, we summarize the progress in defining current markers relevant to CSA-AKI in the last three years.

Does Interhospital Transfer Influence the Outcomes of Patients Receiving Surgery for Acute Type A Aortic Dissection? Type A Aortic Dissection: Is Transfer Hazardous or Beneficial?

Introduction

The progression of acute type A aortic dissection may cause immediate death, such that, in the event of its diagnosis, emergency surgery is indicated. Relatedly, an interhospital transfer may prolong the time from diagnosis to surgery. This study therefore investigated how interhospital transfers impact surgical outcomes for acute type A aortic dissection.

Materials and Methods

After excluding those patients who received deferred surgery for acute type A aortic dissection, 112 patients who received emergency surgery for the condition at our hospital from January 2011 to January 2018 were enrolled. These patients were divided into two groups, one consisting of the patients who were sent directly to our emergency department (group 1) and the other consisting of the patients who were transferred from another hospital after first being diagnosed with type A aortic dissection (group 2). The collected data included the patient demographics, clinical characteristics, operative findings and methods, postoperative outcomes, latest follow-up time, and most recent status.

Results

There were 59 patients in group 1 and 53 patients in group 2. Univariate analysis revealed that group 1 had significantly more patients with a previous stroke (p = 0.007). Moreover, the average length of time from receiving a computed tomography (CT) scan to entering the operating room (OR) was shorter for the group 1 patients (p < 0.001). However, except for the incidence of postoperative acute kidney injury (14.5% versus 33.3%, p = 0.024), there was no statistical difference between the groups in terms of the operative findings and outcomes, such as hypotension before cardiopulmonary bypass, hemopericardium, other complications, and survival rate. Multivariate analysis showed that the independent predictors of hospital mortality included age > 61.5 years (p = 0.017), respiratory rate upon admission > 18.5 breaths/minute (p = 0.046), and total bypass time > 265.6 minutes (p = 0.015). For the patients who survived to discharge, log-rank analysis demonstrated similar cumulative survival rates for the two groups (p = 0.62). Further multivariate analysis showed that the risk of death after discharge was associated with the interval between the CT scan and OR entry (hazard ratio = 0.97 per minute; 95% confidence interval, 0.950–0.998; p = 0.037).

Conclusion

In this study, it was found that interhospital transfer did not influence the surgical outcomes of patients with acute type A aortic dissection. As such, it can be concluded that the transfer of the patients with type A aortic dissection to tertiary hospitals with experienced cardiac surgical teams may not increase the surgical risk.

Acute Kidney Injury after Cardiac Surgery in Patients Without Chronic Kidney Disease

Introduction

Among patients undergoing cardiac surgery, the occurrence of acute renal injury appears to be associated with worse prognosis and increased mortality. The objective of this study was to evaluate risk factors and the impact this complication on mortality and survival after cardiac surgery among patients without chronic kidney disease.

Methods

In this retrospective study, we reviewed the medical records of 142 patients who underwent elective coronary artery bypass grafting, valve replacement (single or multiple), or both (simultaneously) at a tertiary care hospital.

Results

Among the 142 patients evaluated, the mean age was 58.28±13.87 years and 80 (56.33%) were female. The postoperative incidence of acute renal injury was 43.66%. Univariate analysis between the groups with and without acute renal injury revealed no significant differences, whereas multivariate analysis showed that risk factors for acute renal injury included valve replacement (OR=4.7, P=0.002, 95% CI=1.76-12.62, age (OR=1.044, P=0.012, 95% CI=1.01-1.07), previous cardiac surgery (OR=36.1, P=0.015, 95% CI=1.99-653.85), postoperative use of the vasoactive drug norepinephrine (OR=3.32, P=0.013, 95% CI=1.29-8.58) and dobutamine (OR=5.3, P=0.019, 95% CI=1.32-21.64). In our sample, there were 30 deaths, of which 25 had acute kidney injury. Survival was also lower among the patients with this complication, especially those who had required hemodialysis (OR=2.60, P<0.001, 95% CI=1.01-6.70) or had previously undergone cardiac surgery (OR=3.68, P<0.001, 95% CI=1.09-12.37).

Conclusion

Our findings underscore the importance of identifying risk factors for developing acute renal injury after cardiac surgery, which can further the development of effective renoprotective strategies.

Potentially Modifiable Predictors for Renal Replacement Therapy in Patients with Cardiac Surgery Associated-Acute Kidney Injury: a Propensity Score-Matched Case-Control Study

OBJECTIVE

To discover potentially modifiable perioperative predictors for renal replacement therapy (RRT) in patients with cardiac surgery-associated acute kidney injury (CSA-AKI).

METHODS

A cohort of 1773 consecutive cardiac surgery patients with postoperative acute kidney injury (AKI) from January 2013 to December 2015 were included retrospectively. AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. The primary outcome was CSA-AKI requiring renal replacement therapy (AKI-RRT). The initiation of RRT was based on clinical judgment regarding severe volume overload, metabolic abnormality (e.g., acidosis, hyperkalemia), and oliguria. Patients with AKI-RRT were matched 1:1 with patients without AKI-RRT by a propensity score, to exclude the influence of patients' demographics, comorbidities, and baseline renal function. Multivariable regression was performed to identify the predictors in the matched sample.

RESULTS

AKI-RRT occurred in 4.4% of the entire cohort (n=78/1773), with 28.2% of in-hospital mortality (n=22/78). With the propensity score, 78 pairs of patients were matched 1:1 and the variables found to be predictors of AKI-RRT included the contrast exposure within 3 days before surgery (odds ratio [OR]=2.932), central venous pressure (CVP) >10 mmHg on intensive care unit (ICU) admission (OR=1.646 per mmHg increase), and erythrocyte transfusions on the 1st day of surgery (OR=1.742 per unit increase).

CONCLUSION

AKI-RRT is associated with high mortality. The potentially modifiable predictors found in this study require concern and interventions to prevent CSA-AKI patients from worsening prognosis.

Comparison of intraoperative versus intraoperative plus postoperative hemoadsorption therapy in cardiac surgery patients with endocarditis

Infective endocarditis is caused by a bacterial infection of the endocardial surface, and despite improvements in surgical interventions and antimicrobial therapy, mortality remains high. Recently published data suggest that intraoperative hemoadsorption therapy might represent a promising treatment option; however, randomized data still lack, and a comparative study on the intraoperative versus intraoperative plus postoperative use of CytoSorb has not yet been performed. We hypothesized that patients developing intraoperative renal failure benefit from additional postoperative CytoSorb treatment in terms of outcome. We examined the application of hemoadsorption therapy in 20 endocarditis patients separated into two groups: (1) sole intraoperative versus (2) intraoperative plus postoperative treatment, with regard to inflammatory and hemodynamic status, the postoperative course including development of complications, extent of extracorporeal organ support, and outcome. Despite an obviously more pronounced disease severity in the intraoperative plus postoperatively treated patients as evidenced by a higher initial European System for Cardiac Operative Risk Evaluation score, higher reoperation rate, longer cardiopulmonary bypass times, a worse inflammatory status, and perioperative development of acute renal failure, we observed a clear and comparable stabilization in hemodynamics and inflammatory parameters in both groups. More importantly and despite a higher rate of postoperative complications and a longer intensive care unit stay, patients from the intraoperative plus postoperative group showed an equal intensive care unit and 90-day survival compared to patients treated only intraoperatively. Our data suggest that postoperative continuation of hemoadsorption treatment might be beneficial in patients with endocarditis who develop perioperative renal failure in combination with severe hemodynamic instability and high-grade intraoperative findings.

Predictors of Postoperative Acute Kidney Injury after Coronary Artery Bypass Graft Surgery

Objective

The aims of this study were to identify the risk factors associated with acute kidney injury (AKI) after isolated surgical revascularization with cardiopulmonary bypass and to develop a model to predict the appearance of postoperative AKI.

Methods

A total of 435 adult patients who underwent primary isolated coronary artery bypass graft (CABG) surgery, from 2012 to 2016, in the Clinic University Hospital of Valladolid (Spain) were enrolled. AKI was defined according to the risk, injury, failure, loss, and end-stage (RIFLE) criteria. Data were collected from hospital electronic medical records. Multiple logistic regression analysis was used to identify risk factors.

Results

The prevalence of AKI was 12.4%. Multivariate analysis identified age (odds ratio [OR], 1.056; 95% confidence interval [CI], 1.016-1.098; P=0.005), hypertension (OR, 3.078; 95% CI, 1.151-8.230; P=0.018), low ejection fraction (EF) (OR, 6.785; 95% CI, 2.080-22.135; P=0.001), estimated glomerular filtration rate (eGFR) (OR, 1.017; 95% CI, 1.005-1.028; P=0.014), EuroSCORE II (OR, 1.049; 95% CI, 1.004-1.096; P=0.033), and no intake of calcium-channel blockers (CCB) (OR, 4.892; 95% CI, 1.496-16.025; P=0.022) as risk factors for AKI. These risk factors were included in a model to predict postoperative AKI with an area under a receiver operating characteristic curve of 0.783±0.036 (95% CI, 0.713-0.854; P<0.0001).

Conclusion

Age, hypertension, low EF, eGFR, EuroSCORE II, and no intake of CCB were independent risk factors for postoperative AKI. These factors provide an easy and accurate model to predict postoperative AKI in patients undergoing cardiac surgery.

Enteral Baicalin, a Flavone Glycoside, Reduces Indicators of Cardiac Surgery-Associated Acute Kidney Injury in Rats

Background/Aims: Cardiac surgery-associated acute kidney injury (CSA-AKI) is one of the most common postoperative complications in intensive care medicine. Baicalin has been shown to have anti-inflammatory and antioxidant roles in various disorders. We aimed to test the protective effects of baicalin on CSA-AKI using a rat model. Methods: Sprague-Dawley rats underwent 75 min of cardiopulmonary bypass (CPB) with 45 min of cardioplegic arrest (CA) to establish the AKI model. Baicalin was administered at different doses intragastrically 1 h before CPB. The control and treated rats were subjected to the evaluation of different kidney injury index and inflammation biomarkers. Results: Baicalin significantly attenuated CPB/CA-induced AKI in rats, as evidenced by the lower levels of serum creatinine, serum NGAL, and Kim1. Baicalin remarkably inhibited oxidative stress, reflected in the decreased malondialdehyde and myeloperoxidase activity, and enhanced superoxide dismutase activity and glutathione in renal tissue. Baicalin suppressed the expression of IL-18 and iNOS, and activated the Nrf2/HO-1 pathway. Conclusion: Our data indicated that baicalin mediated CPB/CA-induced AKI by decreasing the oxidative stress and inflammation in the renal tissues, and that baicalin possesses the potential to be developed as a therapeutic tool in clinical use for CSA-AKI.

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.

The Accuracy of Urinary TIMP-2 and IGFBP7 for the Diagnosis of Cardiac Surgery-Associated Acute Kidney Injury: A Systematic Review and Meta-Analysis

Background:

Tissue inhibitor of metalloproteinase 2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7) are recent promising markers for identification of cardiac surgery-associated acute kidney injury (CSA-AKI). The aim of this study was systematically and quantitatively to evaluate the accuracy of urinary TIMP-2 and IGFBP7 for the diagnosis of CSA-AKI.

Methods:

Three databases including PubMed, ISI web of knowledge, and Embase were systematically searched from inception to March 2018. Two investigators conducted the processes of literature search study selection, data extraction, and quality evaluation independently. Meta-DiSc and STATA were used for all statistical analyses.

Results:

A total of 8 studies comprising 552 patients were included in this meta-analysis. Pooled sensitivity and specificity with corresponding 95% confidence intervals (CIs) were 0.79 (95% CI, 0.71-0.86, I 2 = 74.2%) and 0.76 (95% CI, 0.72-0.80, I 2 = 80.8%), respectively. Pooled positive likelihood ratio (LR), negative LR, and diagnostic odds ratio were 3.49 (95% CI, 2.44-5.00, I 2 = 61.5%), 0.31(95% CI, 0.19-0.51, I 2 = 51.8%), and 14.89 (95% CI, 7.31-30.32, I 2 = 27.9%), respectively. The area under curve estimated by summary receiver operating characteristic was 0.868 (standard error [SE] 0.032) with a Q* value of 0.799 (SE 0.032). Sensitivity analysis demonstrated that one study notably affected the stability of pooled results. One of the subgroups investigated—AKI threshold—could account for partial heterogeneity.

Conclusion:

Urinary TIMP-2 and IGFBP7 is a helpful biomarker for early diagnosis of CSA-AKI. And, the potential of this biomarker with a broader spectrum of clinical settings may be the focus of future studies.

Postoperative kidney oxygen saturation as a novel marker for acute kidney injury after adult cardiac surgery

OBJECTIVE

Acute kidney injury is a severe complication and one of the stronger risk factors for death in patients undergoing cardiac surgery. The relationship between postoperative brain oxygen saturation and kidney oxygen saturation with acute kidney injury in adults undergoing cardiac surgery has not been determined. We designed a single-center prospective study to determine if the continuous monitoring of postoperative brain oxygen saturation and kidney oxygen saturation could predict postoperative acute kidney injury.

METHODS

We conducted a prospective open cohort study from January to September 2017. The primary outcome was postoperative acute kidney injury using the Kidney Disease: Improving Global Outcomes criteria. Brain oxygen saturation and kidney oxygen saturation, the metrics of which were area measurements (%-min), were recorded during the surgery and the first 48 hours after the cardiac procedure. Receiver operating characteristic curve analysis was used to evaluate the predictive power of kidney oxygen saturation for acute kidney injury.

RESULTS

A total of 121 consecutive patients were enrolled. Thirty-five patients (28.9%) developed acute kidney injury. Brain oxygen saturation showed no statistical difference in both groups; however, kidney oxygen saturation was related to acute kidney injury (P = .001). Receiver operating characteristic curve analysis showed that kidney oxygen saturation could predict the risk of acute kidney injury. Kidney oxygen saturation less than 65% (area under the curve-receiver operating characteristic, 0.679 ± 0.054, 95% confidence interval, 0.573-0.785, P = .002) and 20% decrease from baseline (area under the curve-receiver operating characteristic, 0.639 ± 0.059, 95% confidence interval, 0.523-0.755, P = .019) showed the better performance, respectively.

CONCLUSIONS

Postoperative kidney oxygen saturation is related to the development of cardiac surgery-associated acute kidney injury. Continuous kidney saturation monitoring might be a promising, noninvasive tool for predicting acute kidney injury during the postoperative period for adult patients after cardiac surgery.

Dexmedetomidine prevents acute kidney injury after adult cardiac surgery: a meta-analysis of randomized controlled trials

BACKGROUND

Dexmedetomidine has been shown to confer direct renoprotection by stabilizing the sympathetic system, exerting anti-inflammatory effects and attenuating ischemia/reperfusion (I/R) injury in preclinical studies. Results from clinical trials of dexmedetomidine on acute kidney injury (AKI) following adult cardiac surgery are controversial.

METHODS

We searched EMBASE, PubMed, and Cochrane CENTRAL databases for randomized controlled trials (RCTs) comparing the renal effect of dexmedetomidine versus placebo or other anesthetic drugs in adult patients undergoing cardiac surgery. The primary outcome was the incidence of AKI. The secondary outcomes were mechanical ventilation (MV) duration, intensive care unit (ICU) stay and hospital length of stay(LOS), and postoperative mortality (in-hospital or within 30 days).

RESULTS

Ten trials with a total of 1575 study patients were selected. Compared with controls, dexmedetomidine significantly reduced the incidence of postoperative AKI [68/788 vs 97/787; odds ratio(OR), 0.65; 95% confidence interval (CI), 0.45-0.92; P = 0.02; I² = 0.0%], and there was no difference between groups in postoperative mortality (4/487 vs 11/483; OR, 0.43; 95% CI, 0.14-1.28; P = 0.13; I² = 0.0%), MV duration [in days; n = 1229; weighted mean difference(WMD), -0.22; 95% CI, -2.04 to 1.70; P = 0.81], ICU stay (in days; n = 1363; WMD, -0.85; 95% CI, -2.14 to 0.45; P = 0.20), and hospital LOS (in days; n = 878; WMD, -0.24; 95% CI, -0.71 to 0.23; P = 0.32).

CONCLUSIONS

Perioperative administration of dexmedetomidine in adult patients undergoing cardiac surgery may reduce the incidence of postoperative AKI. Future trials are needed to determine the dose and timing of dexmedetomidine in improving outcomes, especially in patients with decreased baseline kidney function.

The diagnostic accuracy of urinary [TIMP-2]·[IGFBP7] for acute kidney injury in adults: A PRISMA-compliant meta-analysis

INTRODUCTION

Early diagnosis of acute kidney injury (AKI) remains a challenge. Recently, [TIMP-2]·[IGFBP7], which is a combination of urine tissue inhibitor of metalloproteinase 2 (TIMP-2) and insulin-like growth factor (IGF) binding protein 7 (IGFBP7), has been identified as a potential biomarker of AKI. We performed this meta-analysis to assess the diagnostic accuracy of urinary [TIMP-2]·[IGFBP7] for AKI in adult patients.

METHODS

We searched the PubMed, Embase, and Cochrane Library databases from database inception to March 2017. Two authors independently screened articles based on inclusion and exclusion criteria and assessed the methodological quality of each included study using the Quality Assessment of Diagnostic Accuracy Studies 2 criteria. Review Manager and STATA were used for all statistical analyses.

RESULTS

Nine studies (n = 1886) satisfied the inclusion criteria. Pooled analyses demonstrated that urinary [TIMP-2]·[IGFBP7] exhibited fair diagnostic accuracy for AKI (sensitivity [SEN] 0.83 [95% CI 0.75-0.89], specificity [SPE] 0.72 [95% CI 0.56-0.84], and area under the summary receiver operating characteristic [SROC] curve 0.86 [95% CI 0.82-0.88]) and AKI stage ≥ 2 (according to the 2012 Kidney Disease: Improving Global Outcomes [KDIGO] 2012 classification system; SEN 0.92 [95% CI 0.81-0.96], SPE 0.63 [95% CI 0.49-0.74], and area under the SROC curve 0.88 [95% CI 0.85-0.91]) in adult patients.

CONCLUSION

Our findings indicate that urinary [TIMP-2]·[IGFBP7] may be a reliable biomarker for the early detection of AKI. However, given the significant heterogeneity among the included studies, clinicians should be aware of the utility and limitations of this biomarker in clinical practice. Additional high-quality studies examining a larger sample of patients are required.

Incidence and progression of cardiac surgery-associated acute kidney injury and its relationship with bypass and cross clamp time

INTRODUCTION

Cardiac surgery-associated kidney injury (CSA-AKI) is common but relatively less is known about its progression. The present study is aimed at evaluating the incidence and course of CSA-AKI and its relationship with the different durations of cardiopulmonary bypass (CPB) and cross clamp times.

MATERIALS AND METHODS

Occurrences of CSA-AKI are evaluated as per the Akin Kidney Injury Network (AKIN) criteria over the course of 5 postoperative day (POD) in 100 patients. The relationship of different durations of CPB and aortic cross clamp time with CSA-AKI is analyzed by Chi-squared test for trend and other appropriate tests using INSTAT software.

RESULTS

One hundred (43 male, 57 female; mean age of 37.01 ± 12.28 years, and baseline mean serum creatinine 0.99 ± 0.20 mg %) patients undergone mostly valve replacement, and congenital heart disease correction was evaluated. Nearly 49% suffered CSA-AKI (81.63% AKIN Class I) with maximum numbers on 2 nd POD. Serum creatinine followed a falling trend 3 rd POD onward except in 8.16% cases of CSA-AKI. Oliguria was absent even in AKIN Class II. The CPB time >70 min and cross clamp time >60 min increase CSA-AKI risk by an OR of 4.76 and 2.84, respectively (P < 0.05).

CONCLUSION

CSA-AKI is very prevalent; mostly of AKIN Class I and increases with increasing CPB and cross clamp time. Urine output is not a reliable indicator of CSA-AKI. The AKIN Class II on the very 1 st POD or increasing trend of serum creatinine beyond 3 rd POD should alert for early intervention.