Mortality and cost of acute and chronic kidney disease after cardiac surgery

Relationship between intraoperative blood pressure variability and postoperative acute kidney injury in pediatric cardiac surgery

BACKGROUND

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a notably common complication in pediatrics, with an incidence rate ranging from 15 to 64%. This rate is significantly higher than that observed in adults. Currently, there is a lack of substantial evidence regarding the association between intraoperative blood pressure variability (BPV) during cardiac surgery with cardiopulmonary bypass (CPB) and the development of AKI in pediatric patients.

METHODS

This retrospective observational study encompassed children aged 0-7 years undergoing cardiac surgery with CPB. Intraoperative BPV was calculated using coefficients of variation (CVs) and the area under the curve (AUC). Univariate and multivariate analyses were employed to identify risk factors associated with CSA-AKI.

RESULTS

Among 570 patients (median age 1 year) reviewed, 36.1% developed CSA-AKI (68.9% risk stage, 22.8% injury stage, and 8.3% failure stage). After adjusting for other variables, male gender (OR = 2.044, 95% CI 1.297-3.222, P = 0.002), congenital heart surgery risk assessment grade (RACHS-1) classification ≥ 3 (OR = 0.510, 95% CI 0.307-0.846, P = 0.009), longer CPB time (OR = 1.022, 95% CI 1.007-1.037, P = 0.004) and higher peak value of intraoperative vasoactive inotropic score (VIS) (OR = 1.072, 95% CI 1.026-1.119, P = 0.002) were identified as independent risk factors for CSA-AKI. ± 30% AUCm was different in univariate analysis (P = 0.014), however, not statistically different in multifactor analysis (P = 0.610).

CONCLUSION

Greater BPV, specifically MAP variations exceeding 30% AUC during CPB, may be a potential risk factor for CSA-AKI in pediatric patients. Further large sample clinical studies are warranted to analyze the correlation between BPV and CSA-AKI.

Kidney Injury Following Cardiac Surgery: A Review of Our Current Understanding

Around one-quarter of all patients undergoing cardiac procedures, particularly those on cardiopulmonary bypass, develop cardiac surgery-associated acute kidney injury (CSA-AKI). This complication increases the risk of several serious morbidities and of mortality, representing a significant burden for both patients and the healthcare system. Patients with diminished kidney function before surgery, such as those with chronic kidney disease, are at heightened risk of developing CSA-AKI and have poorer outcomes than patients without preexisting kidney injury who develop CSA-AKI. Several mechanisms are involved in the development of CSA-AKI; injury is primarily thought to result from an amplification loop of inflammation and cell death, with complement and immune system activation, cardiopulmonary bypass, and ischemia-reperfusion injury all contributing to pathogenesis. At present there are no effective, targeted pharmacological therapies for the prevention or treatment of CSA-AKI, although several preclinical trials have shown promise, and clinical trials are under way. Progress in the understanding of the complex pathophysiology of CSA-AKI is needed to improve the development of successful strategies for its prevention, management, and treatment. In this review, we outline our current understanding of CSA-AKI development and management strategies and discuss potential future therapeutic targets under investigation.

Role of traditional and new biomarkers in the assessment of chronic kidney diseases: a comprehensive analysis of the biochemical, molecular and clinical dimensions

BACKGROUND

Kidney function is necessary for the diagnosis and treatment of renal diseases. Traditional biomarkers like creatinine have limitations due to their susceptibility to interference and fluctuation. This study's objective is to test and compare the efficacy of conventional and innovative biomarkers in evaluating kidney function and disease.

METHODS

We looked at creatinine, cystatin C, parathyroid hormone (PTH), electrolytes, interleukin-6 (IL-6), C-reactive protein (CRP), the APA I gene, and kidney injury molecule-1 (KIM-1). The present study focused on the stability, sensitivity, and specificity of biomarkers using a combination of traditional and innovative analytical techniques.

RESULTS

Present results showed that creatinine, although commonly used as a measure, frequently overestimates renal function as a result of chromogenic interference. On the other hand, cystatin C showed better sensitivity and was less reliant on influences outside the kidneys. Kidney biomarkers, such as KIM-1, exhibit the potential for identifying acute kidney injury at an early stage. Furthermore, there was a positive correlation between increased levels of CRP and PTH and the progression of kidney disease to more advanced stages.

CONCLUSION

This study emphasizes the importance of combining traditional and new biomarkers to improve the accuracy of diagnosing and managing kidney illness. The more effective use of biomarkers will result in improved patient outcomes.

Association between muscular tissue desaturation and acute kidney injury in patients after surgery for acute type A aortic dissection: a single-center retrospective study

BACKGROUND

A significant association between muscular tissue oxygen saturation (SmtO2), measured by near-infrared spectroscopy (NIRS), and postoperative complications has been observed in patients undergoing major surgery. However, the association between muscular tissue desaturation and acute kidney injury (AKI) has not yet been reported in patients following surgery for acute type A aortic dissection.

METHOD

One hundred seventy-four adult patients who underwent total aortic arch replacement (TAAR) under cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) for acute type A aortic dissection were retrospectively analyzed. Muscular tissue oxygen saturation (SmtO2) in the gastrocnemius muscle region and regional cerebral oxygen saturation (rScO2) on the bilateral forehead were measured using near-infrared spectroscopy (NIRS).The thresholds defining muscular tissue desaturation were SmtO2 < 80%, < 85%, and < 90% of baseline (relative changes compared to the baseline) and < 55% and < 50% (absolute values). Cerebral desaturation was defined as rScO2 < 55%, < 50%, and < 80% baseline, on either the left or right side. The baseline, minimum, and mean values of SmtO2 and rScO2 were also extracted for analysis. The primary objective of this study was to investigate the association between muscular tissue desaturation and AKI.

RESULT

AKI occurred in 71 (40.80%) of the 174 patients underwent TAAR under CPB and DHCA. SmtO2 < 80% of baseline was associated with an increased risk of AKI (odds ratio [OR], 1.021; 95% confidence interval [CI], 1.001-1.041; P = 0.034). A receiver operating characteristic curve showed that the optimal cutoff for SmtO2 < 80% baseline duration was 33.5 min in predicting AKI (sensitivity, 70.00%; specificity, 77.80%). The durations of SmtO2 < 85% baseline (OR, 1.009; 95% CI, 0.996-1.021; P = 0.195) and < 90% baseline (OR,1.007; 95% CI, 0.996-1.018; P = 0.208) were not significantly associated with AKI. There were no significant differences in the durations of absolute SmtO2 values < 55% and < 50% or in the minimum SmtO2 between the two cohorts. Durations of left and right rScO2 < 55%, < 50%, and < 80% baseline were not associated with AKI. Patients with AKI experienced significantly higher in-hospital mortality and more postoperative complications compared with non-AKI patients.

CONCLUSION

Muscular tissue desaturation, defined as SmtO2 < 80% of baseline monitored on the lower leg, was significantly associated with an increased risk of AKI in patients who underwent TAAR under CPB and DHCA. Cerebral desaturation, defined as absolute rScO2 < 55% or < 50%, or < 80% baseline was not associated with AKI.

Alliin mitigates the acute kidney injury by suppressing ferroptosis via regulating the Nrf2/GPX4 axis

Acute kidney injury (AKI) is a clinical syndrome that is characterized by a sudden loss of kidney function, leading to severe metabolic disorders, multiple organ failure, and even death. Recent studies have strengthened the evidence for ferroptosis in AKI development. Alliin, a sulfur-containing amino acid with multiple pharmacological functions, was claimed with promising antioxidant and anti-inflammation effects in protecting organ damages. Herein, Alliin's potential in AKI treatment was investigated by exploring its impact on ferroptosis, providing a new strategy for clinical AKI treatments. Cecal ligation and puncture (CLP) modeling was performed on rats, followed by treated with 7.5 and 15 mg/kg/day of alliin for 6 days. A declined survival rate, severe renal pathological changes, renal dysfunction, and enhanced inflammatory state were observed in CLP-treated rats, which were remarkably alleviated by alliin. Moreover, increased MDA levels, declined SOD activity, and downregulated Nrf2, GPX4, and xCT in CLP-treated rats were notably reversed by alliin. To explore potential mechanisms of alliin, NRK-52E cells were stimulated with 1 μg/mL LPS for 24 h, followed by culturing with 30 and 100 μM of alliin for 24 h. Reduced cell viability, enhanced apoptosis, increased ROS production, boosted MDA level, and declined SOD activity were observed in LPS-stimulated NRK-52E cells, accompanied by downregulated Nrf2, GPX4, and xCT, which were strikingly ameliorated by alliin. Additionally, the influence of alliin on cell viability, oxidative stress (OS), and ferroptosis in LPS-stimulated NRK-52E cells were markedly abolished by silencing Nrf2. Collectively, alliin mitigated AKI by suppressing ferroptosis via regulating the Nrf2/GPX4 axis.

Clinical profile and outcomes in patients with moderate to severe aortic stenosis with or without concomitant chronic kidney disease

INTRODUCTION

Management of aortic stenosis (AS) in patients with chronic kidney disease (CKD) may often be overlooked, and this could confer poorer outcomes.

METHODS

Consecutive patients ( n = 727) with index echocardiographic diagnosis of moderate to severe AS (aortic valve area <1.5 cm 2 ) were examined. They were divided into those with CKD (estimated glomerular filtration rate < 60 mL/min) and those without. Baseline clinical and echocardiographic parameters were compared, and a multivariate Cox regression model was constructed. Clinical outcomes were compared using Kaplan-Meier curves.

RESULTS

There were 270 (37.1%) patients with concomitant CKD. The CKD group was older (78.0 ± 10.3 vs. 72.1 ± 12.9 years, P < 0.001), with a higher prevalence of hypertension, diabetes mellitus, hyperlipidaemia and ischaemic heart disease. AS severity did not differ significantly, but left ventricular (LV) mass index (119.4 ± 43.7 vs. 112.3 ± 40.6 g/m 2 , P = 0.027) and Doppler mitral inflow E to annular tissue Doppler e' ratio (E: e' 21.5 ± 14.6 vs. 17.8 ± 12.2, P = 0.001) were higher in the CKD group. There was higher mortality (log-rank 51.5, P < 0.001) and more frequent admissions for cardiac failure (log-rank 25.9, P < 0.001) in the CKD group, with a lower incidence of aortic valve replacement (log-rank 7.12, P = 0.008). On multivariate analyses, after adjusting for aortic valve area, age, left ventricular ejection fraction and clinical comorbidities, CKD remained independently associated with mortality (hazard ratio 1.96, 95% confidence interval 1.50-2.57, P < 0.001).

CONCLUSION

Concomitant CKD in patients with moderate to severe AS was associated with increased mortality, more frequent admissions for cardiac failure and a lower incidence of aortic valve replacement.

Intraoperative hypotension and postoperative acute kidney injury: A systematic review

BACKGROUND

There is no consensus regarding safe intraoperative blood pressure thresholds that protect against postoperative acute kidney injury (AKI). This review aims to examine the existing literature to delineate safe intraoperative hypotension (IOH) parameters to prevent postoperative AKI.

METHODS

PubMed, Cochrane Central, and Web of Science were systematically searched for articles published between 2015 and 2022 relating the effects of IOH on postoperative AKI.

RESULTS

Our search yielded 19 articles. IOH risk thresholds ranged from <50 to <75 ​mmHg for mean arterial pressure (MAP) and from <70 to <100 ​mmHg for systolic blood pressure (SBP). MAP below 65 ​mmHg for over 5 ​min was the most cited threshold (N ​= ​13) consistently associated with increased postoperative AKI. Greater magnitude and duration of MAP and SBP below the thresholds were generally associated with a dose-dependent increase in postoperative AKI incidence.

CONCLUSIONS

While a consistent definition for IOH remains elusive, the evidence suggests that MAP below 65 ​mmHg for over 5 ​min is strongly associated with postoperative AKI, with the risk increasing with the magnitude and duration of IOH.

Adverse renal effects associated with cardiopulmonary bypass

Cardiac surgery on cardiopulmonary bypass (CPB) is associated with postoperative renal dysfunction, one of the most common complications of this surgical cohort. Acute kidney injury (AKI) is associated with increased short-term morbidity and mortality and has been the focus of much research. There is increasing recognition of the role of AKI as the key pathophysiological state leading to the disease entities acute and chronic kidney disease (AKD and CKD). In this narrative review, we will consider the epidemiology of renal dysfunction after cardiac surgery on CPB and the clinical manifestations across the spectrum of disease. We will discuss the transition between different states of injury and dysfunction, and, importantly, the relevance to clinicians. The specific facets of kidney injury on extracorporeal circulation will be described and the current evidence evaluated for the use of perfusion-based techniques to reduce the incidence and mitigate the complications of renal dysfunction after cardiac surgery.

Perioperative Care in Cardiac Surgery: A Joint Consensus Statement by the Enhanced Recovery After Surgery (ERAS) Cardiac Society, ERAS International Society, and The Society of Thoracic Surgeons (STS)

Enhanced Recovery After Surgery (ERAS) programs have been shown to lessen surgical insult, promote recovery, and improve postoperative clinical outcomes across a number of specialty operations. A core tenet of ERAS involves the provision of protocolized evidence-based perioperative interventions. Given both the growing enthusiasm for applying ERAS principles to cardiac surgery and the broad scope of relevant interventions, an international, multidisciplinary expert panel was assembled to derive a list of potential program elements, review the literature, and provide a statement regarding clinical practice for each topic area. This article summarizes those consensus statements and their accompanying evidence. These results provide the foundation for best practice for the management of the adult patient undergoing cardiac surgery.

Zero-contrast transcatheter closure of sinus venosus defect in advanced renal failure

Transcatheter closure of sinus venosus defect (SVD) is an emerging intervention that utilizes a covered stent to redirect the right upper pulmonary vein to the left atrium. Preprocedural computed tomography analysis, as well as the interventional procedure, necessitates the use of radiographic contrast media. Contrast use is prohibited in patients with advanced kidney disease, who also carry high surgical risks of cardiopulmonary bypass. Transesophageal echocardiography-guided catheter intervention with zero contrast use is presented in this report, along with technical details about planning the procedure. Covered stent exclusion of SVD without contrast use has not been reported in the literature so far.

A novel predictive model for poor in-hospital outcomes in patients with acute kidney injury after cardiac surgery

OBJECTIVE

Patients with cardiac surgery-associated acute kidney injury are at risk of renal replacement therapy and in-hospital death. We aimed to develop and validate a novel predictive model for poor in-hospital outcomes among patients with cardiac surgery-associated acute kidney injury.

METHODS

A total of 196 patients diagnosed with cardiac surgery-associated acute kidney injury were enrolled in this study as the training cohort, and 32 blood cytokines were measured. Least absolute shrinkage and selection operator regression and random forest quantile-classifier were performed to identify the key blood predictors for in-hospital composite outcomes (requiring renal replacement therapy or in-hospital death). The logistic regression model incorporating the selected predictors was validated internally using bootstrapping and externally in an independent cohort (n = 52).

RESULTS

A change in serum creatinine (delta serum creatinine) and interleukin 16 and interleukin 8 were selected as key predictors for composite outcomes. The logistic regression model incorporating interleukin 16, interleukin 8, and delta serum creatinine yielded the optimal performance, with decent discrimination (area under the receiver operating characteristic curve: 0.947; area under the precision-recall curve: 0.809) and excellent calibration (Brier score: 0.056, Hosmer-Lemeshow test P = .651). Application of the model in the validation cohort yielded good discrimination. A nomogram was generated for clinical use, and decision curve analysis demonstrated that the new model adds more net benefit than delta serum creatinine.

CONCLUSIONS

We developed and validated a promising predictive model for in-hospital composite outcomes among patients with cardiac surgery-associated acute kidney injury and demonstrated interleukin-16 and interleukin-8 as useful predictors to improve risk stratification for poor in-hospital outcomes among those with cardiac surgery-associated acute kidney injury.

Development and validation of clinical prediction models for acute kidney injury recovery at hospital discharge in critically ill adults

PURPOSE

Acute kidney injury (AKI) recovery prediction remains challenging. The purpose of the present study is to develop and validate prediction models for AKI recovery at hospital discharge in critically ill patients with ICU-acquired AKI stage 3 (AKI-3).

METHODS

Models were developed and validated in a development cohort (n = 229) and a matched validation cohort (n = 244) from the multicenter EPaNIC database to create prediction models with the least absolute shrinkage and selection operator (Lasso) machine-learning algorithm. We evaluated the discrimination and calibration of the models and compared their performance with plasma neutrophil gelatinase-associated lipocalin (NGAL) measured on first AKI-3 day (NGAL_AKI3) and reference model that only based on age.

RESULTS

Complete recovery and complete or partial recovery occurred in 33.20% and 51.23% of the validation cohort patients respectively. The prediction model for complete recovery based on age, need for renal replacement therapy (RRT), diagnostic group (cardiac/surgical/trauma/others), and sepsis on admission had an area under the receiver operating characteristics curve (AUROC) of 0.53. The prediction model for complete or partial recovery based on age, need for RRT, platelet count, urea, and white blood cell count had an AUROC of 0.61. NGAL_AKI3 showed AUROCs of 0.55 and 0.53 respectively. In cardiac patients, the models had higher AUROCs of 0.60 and 0.71 than NGAL_AKI3's AUROCs of 0.52 and 0.54. The developed models demonstrated a better performance over the reference models (only based on age) for cardiac surgery patients, but not for patients with sepsis and for a general ICU population.

CONCLUSION

Models to predict AKI recovery upon hospital discharge in critically ill patients with AKI-3 showed poor performance in the general ICU population, similar to the biomarker NGAL. In cardiac surgery patients, discrimination was acceptable, and better than NGAL. These findings demonstrate the difficulty of predicting non-reversible AKI early.

Serum Fstl1, a novel biomarker screened based on protein array technology, predict acute kidney injury and major renal adverse events after cardiac surgery: A prospective cohort study

BACKGROUND

Acute kidney injury (AKI) is a severe complication after cardiac surgery. The early prediction of AKI can facilitate timely intervention and prevent adverse outcomes. We aimed to identify unique serum biomarker that can be used to facilitate early prediction of AKI after cardiac surgery.

METHODS

A prospective cohort study was performed in cardiac surgery patients, serum samples were collected from 172 patients before surgery, 4 h and 1 day after surgery. We used protein array technology to detect the serum protein expression profile of cardiac surgery-associated AKI (CSA-AKI) patients, and verified the novel biomarker follistatin-like 1 (Fstl1) by expanding the sample size. The primary outcome was AKI, under the definition of Kidney Disease: Improving Global Outcomes (KDIGO).

RESULTS

Patients with AKI had significantly higher serum Fstl1 levels at 4 h after surgery. After multivariate adjustment, the highest quartile of postoperative serum Fstl1 level, compared with the lowest quartile, associated with 56.3-fold higher odds of AKI. Serum Fstl1 at 4 h post-surgery had a high predictive ability for AKI, severe AKI and major renal adverse events(MAKE) (AUC = 0.713, 0.869 and 0.808, respectively). Adding postoperative 4 h serum Fstl1 to the clinical model can significantly improve the predictive performance of the model.

CONCLUSIONS

Higher serum Fstl1 levels at 4 h post-surgery is associated with higher odds of AKI after cardiac surgery, and when added to clinical model and Cleveland Score, serum Fstl1 levels at 4 h after cardiac surgery enhanced early prediction of AKI, severe AKI and MAKE in patients undergoing cardiac surgery.

The Impact of Diabetes on Outcomes and Health Care Costs Following Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Anterior cervical discectomy and fusion (ACDF) is commonly used to treat an array of cervical spine pathology and is associated with good outcomes and low complication rates. Diabetes mellitus (DM) is a common comorbidity for patients undergoing ACDF, but the literature is equivocal about the impact it has on outcomes. Because DM is a highly prevalent comorbidity, it is crucial to determine if it is an associated risk factor for outcomes after ACDF procedures.

METHODS

Patients at a single institution from 2008 to 2016 undergoing ACDF were compared on the basis of having a prior diagnosis of DM versus no DM. The 2 cohorts were compared utilizing univariate tests and multivariate logistic and linear regressions.

RESULTS

Data for 2470 patients was analyzed. Diabetic patients had significantly higher Elixhauser scores (P < .0001). Univariate testing showed diabetic patients were more likely to suffer from sepsis (0.82% vs 0.10%, P = .03) and bleeding complications (3.0% vs 1.5%, P = .04). In multivariate analyses, diabetic patients had higher rates of non-home discharge (odds ratio [OR] = 1.37, 95% confidence interval [CI] = 1.07-1.75, P = .013) and prolonged length of stay (OR = 1.95, 95% CI = 1.25-3.05, P = .003), but similar complication (OR = 1.46, 95% CI = 0.85-2.52, P = .17), reoperation (OR = 0.77, 95% CI = 0.33-1.81, P = .55), and 90-day readmission (OR = 1.53, 95% CI = 0.97-2.43) rates compared to nondiabetic patients. Direct cost was also shown to be similar between the cohorts after adjusting for patient, surgical, and hospital-related factors (estimate = -$30.25, 95% CI = -$515.69 to $455.18, P = .90).

CONCLUSIONS

Diabetic patients undergoing ACDF had similar complication, reoperation, and readmission rates, as well as similar cost of care compared to nondiabetic patients.

Cost of postoperative complications of lower anterior resection for rectal cancer: a nationwide registry study of 15,187 patients

PURPOSE

To assess the increase in hospital costs associated with postoperative complications after lower anterior resection (LAR) for rectal cancer.

METHODS

The subjects of this retrospective analysis were patients who underwent elective LAR surgery between April, 2015 and March, 2017, collected from a Japanese nationwide gastroenterological surgery registry linked to hospital-based claims data. We evaluated total and category-specific hospitalization costs based on the level of postoperative complications categorized using the Clavien-Dindo (CD) classification. We assessed the relative increase in hospital costs, adjusting for preoperative factors and hospital case volume.

RESULTS

We identified 15,187 patients (mean age 66.8) treated at 884 hospitals. Overall, 71.8% had no recorded complications, whereas 7.6%, 10.8%, 9.0%, 0.6%, and 0.2% had postoperative complications of CD grades I-V, respectively. The median (25th-75th percentiles) hospital costs were $17.3 K (16.1-19.3) for the no-complications group, and $19.1 K (17.3-22.2), $21.0 K (18.5-25.0), $27.4 K (22.4-33.9), $41.8 K (291-618), and $22.7 K (183-421) for the CD grades I-V complication groups, respectively. The multivariable model identified that complications of CD grades I-V were associated with 11%, 21%, 61%, 142%, and 70% increases in in-hospital costs compared with no complications.

CONCLUSIONS

Postoperative complications and their severity are strongly associated with increased hospital costs and health-care resource utilization. Implementing strategies to prevent postoperative complications will improve patients' clinical outcomes and reduce hospital care costs substantially.

A new model to predict acute kidney injury after cardiac surgery in patients with renal insufficiency

Objective

To establish a simple model for predicting postoperative acute kidney injury (AKI) requiring renal replacement therapy (RRT) in patients with renal insufficiency (CKD stages 3–4) who underwent cardiac surgery.

Methods

A total of 330 patients were enrolled. Among them, 226 were randomly selected for the development group and the remaining 104 for the validation group. The primary outcome was AKI requiring RRT. A nomogram was constructed based on the multivariate analysis with variables selected by the application of the least absolute shrinkage and selection operator. Meanwhile, the discrimination, calibration, and clinical power of the new model were assessed and compared with those of the Cleveland Clinic score and Simplified Renal Index (SRI) score in the validation group. Results: The rate of RRT in the development group was 10.6% (n = 24), while the rate in the validation group was 14.4% (n = 15). The new model included four variables such as postoperative creatinine, aortic cross‐clamping time, emergency, and preoperative cystatin C, with a C-index of 0.851 (95% CI, 0.779–0.924). In the validation group, the areas under the receiver operating characteristic curves for the new model, SRI score, and Cleveland Clinic score were 0.813, 0.791, and 0.786, respectively. Furthermore, the new model demonstrated greater clinical net benefits compared with the Cleveland Clinic score or SRI score.

Conclusions

We developed and validated a powerful predictive model for predicting severe AKI after cardiac surgery in patients with renal insufficiency, which would be helpful to assess the risk for severe AKI requiring RRT.

CSA-AKI: Incidence, Epidemiology, Clinical Outcomes, and Economic Impact

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a common complication following cardiac surgery and reflects a complex biological combination of patient pathology, perioperative stress, and medical management. Current diagnostic criteria, though increasingly standardized, are predicated on loss of renal function (as measured by functional biomarkers of the kidney). The addition of new diagnostic injury biomarkers to clinical practice has shown promise in identifying patients at risk of renal injury earlier in their course. The accurate and timely identification of a high-risk population may allow for bundled interventions to prevent the development of CSA-AKI, but further validation of these interventions is necessary. Once the diagnosis of CSA-AKI is established, evidence-based treatment is limited to supportive care. The cost of CSA-AKI is difficult to accurately estimate, given the diverse ways in which it impacts patient outcomes, from ICU length of stay to post-hospital rehabilitation to progression to CKD and ESRD. However, with the global rise in cardiac surgery volume, these costs are large and growing.

Effect of a 3% gelatin solution on urinary KIM-1 levels in patients after thyroidectomy: a preliminary randomized controlled trial

Optimal fluid therapy significantly affects the maintenance of proper tissue perfusion and, consequently, kidney function. An adverse effect of colloids on kidney function is related to the incidence of postoperative kidney failure. The study aimed to assess the effect of a 3% gelatin solution on kidney function based on the urinary kidney injury molecule-1 (uKIM-1) level. This study used a parallel design and enrolled 64 adult patients with a mean age of 52.5 ± 13.1 years, all of whom underwent a thyroidectomy procedure under general anesthesia. Patients were randomly assigned to three comparison groups, each receiving a different dose of 3% gelatin solution during the thyroidectomy procedure. The patients from study groups A (n = 21) and B (n = 21) received a 3% gelatin solution at a dose of 30 ml/kg and 15 ml/kg body weight, respectively, during the first hour of the procedure. The patients from the control group C (n = 22) received an isotonic multi-electrolyte solution. Serum creatinine levels were determined, and urine samples were collected to determine levels of uKIM-1 before, 2 h, and 24 h after surgery. The patients' demographic data, type and volume of fluid and hemodynamic status during the surgery were collected from relevant anesthesia protocols and were included in the study data. There were no statistically significant changes between groups in hemodynamic parameters such as systolic and diastolic blood pressure, heart rate, and oxygen saturation values. A statistically significant increase in uKIM-1 level was noted in patients receiving the 3% gelatin solution regardless of the dose. A statistically significant difference in uKIM-1 level was observed between groups A, B, and C measured 24 h after surgery, with the highest uKIM-1 level in group A. Measurement of uKIM-1 level could be an early and sensitive biomarker of kidney injury. Kidney toxicity of a 3% gelatin solution, evaluated based on the level of uKIM-1 in urine, correlates with transfused fluid volume. This study was retrospectively registered in the ISRCTN clinical trials registry (ISRCTN73266049, 08/04/2021: https://www.isrctn.com/ISRCTN73266049 ).

Organizational and financial aspects of a continuous renal replacement therapy program

Critically ill patients who develop severe acute kidney injury in the intensive care unit often require treatment with renal replacement therapies (RRTs). This complication is associated with severe morbidity and mortality and high costs, both during hospitalization and postdischarge. This article discusses the operational requirements to develop and conduct a RRT program, as well as the financial implications of this complex form of patient care. The management of these programs must occur in a context where a clear organizational and educational framework and a multidisciplinary team ensures safety, effectiveness, cost-control, and a clear quality control framework.

In-hospital outcomes of transcatheter mitral valve repair in patients with and without end stage renal disease: A national propensity match study

OBJECTIVES

To study trends of utilization, outcomes, and cost of care in patients undergoing undergoing transcatheter mitral valve repair (TMVr) with end-stage renal disease (ESRD).

BACKGROUND

Renal disease has been known to be a predictor of poor outcome in patients with mitral valve disease. Outcome data for patients with ESRD undergoing TMVr remains limited. Therefore, our study aims to investigate trends of utilization, outcomes, and cost of care among patients with ESRD undergoing TMVr.

METHODS

We analyzed NIS data from January 2010 to December 2017 using the ICD-9-CM codes ICD-10-CM to identify patients who underwent TMVr. Baseline characteristics were compared using a Pearson 𝜒2 test for categorical variables and independent samples t-test for continuous variables. Propensity matched analysis was done for adjusted analysis to compare outcomes between TMVr with and without ESRD. Markov chain Monte Carlo was used to account for missing values.

RESULTS

A total of 15,260 patients (weighted sample) undergoing TMVr were identified between 2010 and 2017. Of these, 638 patients had ESRD compared to 14,631 patients who did not have ESRD. Adjusted in-hospital mortality was lower in non-ESRD group (3.9 vs. <1.8%). Similarly, ESRD patients were more likely to have non-home discharges (85.6 vs. 74.9%). ESRD patients also had a longer mean length of stay (7.9 vs. 13.5 days) and higher mean cost of stay ($306,300 vs. $271,503).

CONCLUSION

ESRD is associated with higher mortality, complications, and resource utilization compared to non-ESRD patients. It is important to include this data in shared decision-making process and patient selection.

Machine learning prediction models for prognosis of critically ill patients after open-heart surgery

We aimed to build up multiple machine learning models to predict 30-days mortality, and 3 complications including septic shock, thrombocytopenia, and liver dysfunction after open-heart surgery. Patients who underwent coronary artery bypass surgery, aortic valve replacement, or other heart-related surgeries between 2001 and 2012 were extracted from MIMIC-III databases. Extreme gradient boosting, random forest, artificial neural network, and logistic regression were employed to build models by utilizing fivefold cross-validation and grid search. Receiver operating characteristic curve, area under curve (AUC), decision curve analysis, test accuracy, F1 score, precision, and recall were applied to access the performance. Among 6844 patients enrolled in this study, 215 patients (3.1%) died within 30 days after surgery, part of patients appeared liver dysfunction (248; 3.6%), septic shock (32; 0.5%), and thrombocytopenia (202; 2.9%). XGBoost, selected to be our final model, achieved the best performance with highest AUC and F1 score. AUC and F1 score of XGBoost for 4 outcomes: 0.88 and 0.58 for 30-days mortality, 0.98 and 0.70 for septic shock, 0.88 and 0.55 for thrombocytopenia, 0.89 and 0.40 for liver dysfunction. We developed a promising model, presented as software, to realize monitoring for patients in ICU and to improve prognosis.

In-Hospital Outcomes of Acute Kidney Injury After Pediatric Cardiac Surgery: A Meta-Analysis

Background: Cardiac surgery-associated acute kidney injury (CS-AKI) is associated with increased morbidity and mortality in both adults and children. This study aimed to investigate the in-hospital outcomes of CS-AKI in the pediatric population. Methods: PubMed/MEDLINE, Embase, Scopus, and reference lists of relevant articles were searched for studies published by August 2020. Random-effects meta-analysis was performed, comparing in-hospital outcomes between patients who developed CS-AKI and those who did not. Results: Fifty-eight publications between 2008 and 2020 consisting of 18,334 participants (AKI: 5,780; no AKI: 12,554) were included. Higher rates of in-hospital mortality (odds ratio [OR] 7.22, 95% confidence interval [CI] 5.27-9.88), need for renal replacement therapy (RRT) (OR 18.8, 95% CI 11.7-30.5), and cardiac arrhythmias (OR 2.67, 95% 1.86-4.80) were observed in patients with CS-AKI. Furthermore, patients with AKI had longer ventilation times (mean difference [MD] 1.76 days, 95% CI 1.05-2.47), pediatric intensive care unit (PICU) length of stay (MD 3.31, 95% CI 2.52-4.10), and hospital length of stay (MD 5.00, 95% CI 3.34-6.67). Conclusions: CS-AKI in the pediatric population is associated with a higher risk of mortality, cardiac arrhythmias and need for RRT, as well as greater mechanical ventilation time, PICU and hospital length of stay. These results might help improve the clinical care protocols prior to cardiac surgery to minimize the disease burden of CS-AKI in children. Furthermore, etiology-specific approaches to AKI are warranted, as outcomes are likely impacted by the underlying cause.

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.

Acute Kidney Injury and Fluid Overload in Pediatric Cardiac Surgery

PURPOSE OF REVIEW

Acute kidney injury (AKI) and fluid overload affect a large number of children undergoing cardiac surgery, and confers an increased risk for adverse complications and outcomes including death. Survivors of AKI suffer long-term sequelae. The purpose of this narrative review is to discuss the short and long-term impact of cardiac surgery associated AKI and fluid overload, currently available tools for diagnosis and risk stratification, existing management strategies, and future management considerations.

RECENT FINDINGS

Improved risk stratification, diagnostic prediction tools and clinically available early markers of tubular injury have the ability to improve AKI-associated outcomes. One of the major challenges in diagnosing AKI is the diagnostic imprecision in serum creatinine, which is impacted by a variety of factors unrelated to renal disease. In addition, many of the pharmacologic interventions for either AKI prevention or treatment have failed to show any benefit, while peritoneal dialysis catheters, either for passive drainage or prophylactic dialysis may be able to mitigate the detrimental effects of fluid overload.

SUMMARY

Until novel risk stratification and diagnostics tools are integrated into routine practice, supportive care will continue to be the mainstay of therapy for those affected by AKI and fluid overload after pediatric cardiac surgery. A viable series of preventative measures can be taken to mitigate the risk and severity of AKI and fluid overload following cardiac surgery, and improve care.

Serum and Urinary NGAL and Cystatin C Levels as Diagnostic Tools for Acute Kidney Injury and Chronic Kidney Disease: A Histobiochemical Comparative Study

BACKGROUND

High global incidence of acute kidney injury (AKI) is an observable complication in critically ill patients. Long-term disease and medication complexity contribute to devastating chronic kidney disease (CKD), diminishing quality of life.

OBJECTIVES

To establish new biomarkers to guide patient care and facilitate novel therapeutics development.

METHODS

Serum and urinary levels of creatinine, CysC, and NGAL were estimated in 86 renal patients and compared with healthy controls for AKI and CKD categorization. Creatinine and CysC measurements were used to estimate GFR. Kidney biopsies were prepared for light microscopy for further characterization. Patients' demographic data were used in group association studies.

RESULTS

Thirty-six patients met the criteria for AKI and 50 for CKD. Both mean serum and urine creatinine levels were significantly elevated by 2.8 and 2.6, respectively, from baseline in 48 h in the AKI group but not CKD group. Mean serum Cystatin C (CysC) values were higher than controls but similar in both disease states, while urine levels were slightly higher in CKD patients, and remained steady by the end of the follow-up (EF-Up). Further, a significant 2.9-fold and 5.5-fold (p=0.001) increase in serum NGAL in AKI and CKD, respectively, and a dramatic 7.1-factor reduction in AKI group, but no appreciable change in the CKD group from admission to EF-Up were observed. Similarly, urine NGAL level for AKI and CKD increased 3.2-fold and 6-fold respectively, on admission, which decreased moderately with the AKI group (2.5-fold) but increased by a factor of 1-8 (10.7- fold; p=0.001) at EF-Up. ROC assessment curve revealed relatively higher NGAL performance at good predictive values than CysC (p < 0.009).

CONCLUSION

Our data demonstrated creatinine elevation by a factor > 2 in 48 h in AKI group but not CKD group, which returned close to normal levels by the EF-Up, an indication of abrupt renal injury in AKI, compared with a persistent effect in the CKD group. Both serum and urine NGAL sensitivity and specificity provided powerful discriminative tool between AKI and CKD by reduction in the AKI group and an increase in the CKD group by the EF-UP, thus, contributing in establishing the basis for AKI and CKD classification. CysC, however, displayed less sensitivity than NGAL, indicating effects by enigmatic non-specific factors.

Acute Kidney Injury in Subjects With Chronic Kidney Disease Undergoing Total Joint Arthroplasty

BACKGROUND

Chronic kidney disease (CKD) has been associated with higher incidence of complications after total joint arthroplasty (TJA) but the incidence, risk factors and outcomes of acute kidney injury (AKI) in this setting remains insufficiently understood.

METHODS

We assessed the impact of baseline CKD on the risk of developing AKI after TJA performed between 1/2012 and 12/2016 in a single-center, retrospective cohort study. CKD was defined by estimated glomerular filtration rate <60 mL/min/1.73 m² on 2 separate occasions within 3 months prior TJA. AKI was defined using a modified Kidney Disease: Improving Global Outcomes criteria based on serum creatinine (sCr) only to assess the severity of AKI. Complete AKI recovery was defined as the lowest post-AKI sCr within 20% of pre-AKI sCr values and partial recovery if within 30%, all within 90 days after TJA.

RESULTS

Twenty-four percent of the 1,212 subjects undergoing TJA had pre-existing CKD. The overall incidence of AKI in the CKD subjects was 30%; of these, 55% had stage-1 AKI, 1% had stage-2 AKI and 44% had stage-3 AKI. AKI was more common in African Americans, those with diabetes or heart failure, requiring perioperative transfusions or receiving diuretics before surgery. While 82% of the AKI subjects achieved complete recovery of kidney function, 4% had only partial recovery and 14% did not reach a post-AKI sCr level within 30% of pre-AKI values. The incidence (P < 0.001) but not the severity (P = 0.202) of AKI correlated with stages of baseline CKD.

CONCLUSIONS

The presence of CKD was associated with a high incidence of AKI after TJA. In these subjects, more than half the cases of AKI were of mild degree and had a favorable outcome. However, 18% of them did not have complete recovery of kidney function. Stages of baseline CKD were associated with increased incidence but not severity of AKI after TJA.

Improved predictive models for acute kidney injury with IDEA: Intraoperative Data Embedded Analytics

BACKGROUND

Acute kidney injury (AKI) is a common complication after surgery that is associated with increased morbidity and mortality. The majority of existing perioperative AKI risk prediction models are limited in their generalizability and do not fully utilize intraoperative physiological time-series data. Thus, there is a need for intelligent, accurate, and robust systems to leverage new information as it becomes available to predict the risk of developing postoperative AKI.

METHODS

A retrospective single-center cohort of 2,911 adults who underwent surgery at the University of Florida Health between 2000 and 2010 was utilized for this study. Machine learning and statistical analysis techniques were used to develop perioperative models to predict the risk of developing AKI during the first three days after surgery, first seven days after surgery, and overall (after surgery during the index hospitalization). The improvement in risk prediction was examined by incorporating intraoperative physiological time-series variables. Our proposed model enriched a preoperative model that produced a probabilistic AKI risk score by integrating intraoperative statistical features through a machine learning stacking approach inside a random forest classifier. Model performance was evaluated using the area under the receiver operating characteristic curve (AUC), accuracy, and Net Reclassification Improvement (NRI).

RESULTS

The predictive performance of the proposed model is better than the preoperative data only model. The proposed model had an AUC of 0.86 (accuracy of 0.78) for the seven-day AKI outcome, while the preoperative model had an AUC of 0.84 (accuracy of 0.76). Furthermore, by integrating intraoperative features, the algorithm was able to reclassify 40% of the false negative patients from the preoperative model. The NRI for each outcome was AKI at three days (8%), seven days (7%), and overall (4%).

CONCLUSIONS

Postoperative AKI prediction was improved with high sensitivity and specificity through a machine learning approach that dynamically incorporated intraoperative data.

Preoperative predictive model for acute kidney injury after elective cardiac surgery: a prospective multicenter cohort study

BACKGROUND

Predictive models of acute kidney injury after cardiac surgery (CS-AKI) include emergency surgery and patients with hemodynamic instability. Our objective was to evaluate the performance of validated predictive models (Thakar and Demirjian) in elective cardiac surgery and to propose a better score in the case of poor performance.

METHODS

A prospective, multicenter, observational study was designed. Data were collected from 942 patients undergoing cardiac surgery, after excluding emergency surgery and patients with an intra-aortic balloon pump. The main outcome measure was CS-AKI defined by the composite of requiring dialysis or doubling baseline creatinine values.

RESULTS

Both models showed poor discrimination in elective surgery (Thakar's model, AUC=0.57, 95% CI: 0.50-0.64 and Demirjian's model, AUC=0.64, 95% CI: 0.58-0.71). We generated a new model whose significant independent predictors were: anemia, age, hypertension, obesity, congestive heart failure, previous cardiac surgery and type of surgery. It classifies patients with scores 0-3 as at low risk (<5%), patients with scores 4-7 as at medium risk (up to 15%), and patients with scores >8 as at high risk (>30%) of developing CS-AKI with a statistically significant correlation (P<0.001). Our model reflects acceptable discriminatory ability (AUC=0.72, 95% CI: 0.66-0.78) which is significantly better than Thakar and Demirjian's models (P<0.01).

CONCLUSIONS

We developed a new simple predictive model of CS-AKI in elective surgery based on available preoperative information. Our new model is easy to calculate and can be an effective tool for communicating risk to patients and guiding decision-making in the perioperative period. The study requires external validation.

Effect of Levosimendan on Renal Outcome in Cardiac Surgery Patients With Chronic Kidney Disease and Perioperative Cardiovascular Dysfunction: A Substudy of a Multicenter Randomized Trial

OBJECTIVE

Acute kidney injury (AKI) occurs frequently after cardiac surgery. Levosimendan might reduce the incidence of AKI in patients undergoing cardiac surgery. The authors investigated whether levosimendan administration could reduce AKI incidence in a high-risk cardiac surgical population.

DESIGN

Post hoc analysis of a multicenter randomized trial.

SETTING

Cardiac surgery operating rooms and intensive care units of 14 centers in 3 countries.

PARTICIPANTS

The study comprised 90 patients who underwent mitral valve surgery with an estimated glomerular filtration rate <60 mL/min/1.73 m² and perioperative myocardial dysfunction.

INTERVENTIONS

Patients were assigned randomly to receive levosimendan (0.025-0.2 μg/kg/min) or placebo in addition to standard inotropic treatment.

MEASUREMENTS AND MAIN RESULTS

Forty-six patients were assigned to receive levosimendan and 44 to receive placebo. Postoperative AKI occurred in 14 (30%) patients in the levosimendan group versus 23 (52%) in the placebo group (absolute difference -21.8; 95% confidence interval -41.7 to -1.97; p = 0.035). The incidence of major complications also was lower (18 [39%]) in the levosimendan group versus that in the placebo group (29 [66%]) (absolute difference -26.8 [-46.7 to -6.90]; p = 0.011). A trend toward lower serum creatinine at intensive care unit discharge was observed in the levosimendan group (1.18 [0.99-1.49] mg/dL) versus that in the placebo group (1.39 [1.05-1.76] mg/dL) (95% confidence interval -0.23 [-0.49 to 0.01]; p = 0.07).

CONCLUSIONS

Levosimendan may improve renal outcome in cardiac surgery patients with chronic kidney disease undergoing mitral valve surgery who develop perioperative myocardial dysfunction. Results of this exploratory analysis should be investigated in future properly designed randomized controlled trials.