Acute kidney injury following cardiac surgery: current understanding and future directions

Implementation of enhanced recovery in cardiac surgery: An experimental study with the control group

INTRODUCTION

The Enhanced Recovery After Cardiac Surgery protocol is the most recent addition to cardiac treatment. In this paper, we aimed to test the safety and viability of this protocol in our hospital to improve our standard of care.

METHODS

This study was conducted as an experimental study with a historical control at the Maritime Heart Center, Halifax, Nova Scotia, Canada. In order to quantify the success of this protocol, we measured the postoperative Length of Hospital Stay and three intensive care unit variables: time to extubation, time to ambulation, and opioid consumption. In the study, 100 patients were in the Enhanced Recovery After Cardiac Surgery group, and 103 patients were used as historic controls-selected by strenuous chart review and selection criteria.

RESULTS

The primary outcome (Length of Hospital Stay) was reduced from a mean of 8.88 ± 3.50 days in the control group to a mean of 5.13 ± 1.34 days in the Enhanced Recovery After Cardiac Surgery group (p < 0.001). Likewise, we observed a significant reduction in intensive care unit variables: time to extubation was reduced from 10.54 ± 7.83 h in the control group to 6.69 ± 1.63 in the Enhanced Recovery After Cardiac Surgery group (p < 0.01), and time to ambulation was reduced from 36.27 ± 35.21 h in the control group to 9.78 ± 2.03 in the Enhanced Recovery After Cardiac Surgery group (p < 0.01) and opioid consumption was reduced from 50.58 ± 11.93 milligram morphine equivalent in the control group to 11.58 ± 4.43 milligram morphine equivalent in the Enhanced Recovery After Cardiac Surgery group (p < 0.01).

CONCLUSION

Enhanced Recovery After Cardiac Surgery protocols were seamlessly integrated into selected cardiac surgical patients, contingent on a high level of interprofessional communication and collaboration.

Association Between Proton Pump Inhibitor Exposure and Acute Kidney Injury After Cardiac Surgery

OBJECTIVE

To evaluate the association of preoperative proton pump inhibitor (PPI) exposure with incident acute kidney injury (AKI) after cardiac surgery.

PATIENTS AND METHODS

The Severance cardiac surgery cohort included 9860 cardiac surgery patients aged 18 years or older. The National Health Insurance Service-senior cohort included 2933 patients aged 60 years or older who underwent cardiac surgery. Preoperative PPI exposure was defined as a PPI prescription within 3 weeks prior to cardiac surgery. Primary outcomes were postoperative AKI and AKI requiring dialysis (AKI-dialysis).

RESULTS

In the Severance cardiac surgery cohort after propensity score matching for PPI exposure, incident AKI (44.0% [472 of 1073] vs 40.5% [1304 of 3219]) and AKI-dialysis (5.8% [62 of 1073] vs 3.7% [119 of 3219]) were more common in patients exposed to PPI than in those who were not. Hospital and intensive care unit stay durations were longer among PPI-exposed than PPI-nonexposed patients. Multivariable conditional logistic analyses revealed that PPI exposure was significantly associated with incident AKI (adjusted odds ratio [AOR], 1.21; 95% CI, 1.03 to 1.42; P=.02) and AKI-dialysis (AOR, 1.74; 95% CI, 1.15 to 2.63; P=.009). The National Health Insurance Service-Senior cohort had similar results, revealing a significant association between PPI exposure and incident AKI-dialysis (AOR, 1.87; 95% CI, 1.25 to 2.81; P=.003). Discontinuation of PPI prior to operation was associated with a lower odds of AKI development in both cohorts.

CONCLUSION

Preoperative PPI exposure may be a modifiable risk factor for AKI among patients undergoing cardiac surgery.

Diagnosis, pathophysiology and preventive strategies for cardiac surgery-associated acute kidney injury: a narrative review

Acute kidney injury (AKI) is a common and serious complication of cardiac surgery and is associated with increased mortality and morbidity, accompanied by a substantial economic burden. The pathogenesis of cardiac surgery-associated acute kidney injury (CSA-AKI) is multifactorial and complex, with a variety of pathophysiological theories. In addition to the existing diagnostic criteria, the exploration and validation of biomarkers is the focus of research in the field of CSA-AKI diagnosis. Prevention remains the key to the management of CSA-AKI, and common strategies include maintenance of renal perfusion, individualized blood pressure targets, balanced fluid management, goal-directed oxygen delivery, and avoidance of nephrotoxins. This article reviews the pathogenesis, definition and diagnosis, and pharmacological and nonpharmacological prevention strategies of AKI in cardiac surgical patients.

Failure to Rescue: A Quality Metric for Cardiac Surgery and Cardiovascular Critical Care

Failure to rescue, defined as mortality after a surgical complication, is a widely accepted quality metric across many specialties and is becoming an important metric in cardiac surgery. The failure to rescue metric provides a target for improvements in patient outcomes after complications occur. To be used appropriately, the failure to rescue metric must be defined using a prespecified set of life-threatening and rescuable complications. Successful patient rescue requires a systematic approach of complication recognition, timely escalation of care, effective medical management, and mitigation of additional complications. This process requires contributions from cardiac surgeons, intensivists, and other specialists including cardiologists, neurologists, and anaesthesiologists. Factors that affect failure to rescue rates in cardiac surgery and cardiovascular critical care include nurse staffing ratios, intensivist coverage, advanced specialist support, hospital and surgical volume, the presence of trainees, and patient comorbidities. Strategies to improve patient rescue include working to understand the mechanisms of failure to rescue, anticipating postoperative complications, prioritizing microsystem factors, enhancing early escalation of care, and educating and empowering junior clinicians. When used appropriately, the failure to rescue quality metric can help institutions focus on improving processes of care that minimize morbidity and mortality from rescuable complications after cardiac surgery.

Single value of NephroCheck™ performed at 4 hours after surgery does not predict acute kidney injury in off-pump coronary artery bypass surgery

Background

Quantification of urinary tissue inhibitor of metalloproteinase-2 (TIMP-2) and insulin-like growth factor binding protein (IFGBP-7), which is commercially known as NephroCheck™(NC) test have been suggested as promising tools for the early detection of acute kidney injury (AKI) after cardiac surgery involving cardio-pulmonary bypass (CPB).

Objectives

The aim of the present study was to test the hypothesis that single value of postoperative NC test performed at 4 hours after surgery can predict AKI in off-pump coronary artery bypass grafting (OPCABG) surgery.

Setting and Design

This prospective single-center study was conducted at the tertiary cardiac center in India from December 2017 to November 2018.

Methods

Ninety adult patients of both sex undergoing elective OPCABG were included. Anesthesia was standardized to all patients. Urine samples were collected preoperatively and at 4 hours after surgery for NC test. Urine output, serum creatinine, estimated glomerular filtration rate (eGFR) were also measured. AKI staging was based on kidney disease improving global outcomes (KDIGO) guidelines.

Statistical Analysis

To assess the predictability of NC test for the primary endpoint, area under the receiver operating characteristic curve (ROC), was calculated.

Results

Thirteen patients developed AKI in the study cohort (14.4%) out of which 7 patients (7.8%) developed stage 2/3 AKI and the remaining stage 1 AKI. Baseline renal parameters were similar between AKI and non-AKI group. The area under curve (AUC) of NC test at 4 hours after surgery was 0.60 [95% confidence interval (CI): 0.42-0.77]. Postoperative NC test performed at 4 hours after surgery did not predict AKI in this study population (P = 0.24). There were no significant differences in duration of mechanical ventilation, length of intensive care stay and hospital stay between the two groups (P > 0.05).

Conclusion

NephroCheck^™ test performed at 4 hours after surgery did not identify patients at risk for developing AKI following OPCABG surgery.

Association between intraoperative oliguria and postoperative acute kidney injury in non-cardiac surgical patients: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to evaluate the association between intraoperative oliguria and the risk of postoperative acute kidney injury (AKI) in patients undergoing non-cardiac surgery.

METHODS

The MEDLINE and EMBASE databases were searched up to August 2022 for studies in adult patients undergoing non-cardiac surgery, where the association between intraoperative urine output and the risk of postoperative AKI was assessed. Both randomised and non-randomised studies were eligible for inclusion. Study selection and risk of bias assessment were independently performed by two investigators. The risk of bias was evaluated using the Newcastle-Ottawa scale. We performed meta-analysis of the reported multivariate adjusted odds ratios for the association between intraoperative oliguria (defined as urine output < 0.5 mL/kg/hr) and the risk of postoperative AKI using the inverse-variance method with random effects models. We conducted sensitivity analyses using varying definitions of oliguria as well as by pooling unadjusted odds ratios to establish the robustness of the primary meta-analysis. We also conducted subgroup analyses according to surgery type and definition of AKI to explore potential sources of clinical or methodological heterogeneity.

RESULTS

Eleven studies (total 49,252 patients from 11 observational studies including a post hoc analysis of a randomised controlled trial) met the selection criteria. Seven of these studies contributed data from a total 17,148 patients to the primary meta-analysis. Intraoperative oliguria was associated with a significantly elevated risk of postoperative AKI (pooled adjusted odds ratio [OR] 1.74; 95% confidence interval [CI] 1.36-2.23, p < 0.0001, 8 studies). Sensitivity analyses supported the robustness of the primary meta-analysis. There was no evidence of any significant subgroup differences according to surgery type or definition of AKI.

CONCLUSIONS

This study demonstrated a significant association between intraoperative oliguria and the risk of postoperative AKI, regardless of the definitions of oliguria or AKI used. Further prospective and multi-centre studies using standardised definitions of intraoperative oliguria are required to define the thresholds of oliguria and establish strategies to minimise the risk of AKI.

Predicting the risk of acute kidney injury after cardiopulmonary bypass: development and assessment of a new predictive nomogram

BACKGROUND

Acute kidney injury (AKI) is a common and severe complication of cardiac surgery with cardiopulmonary bypass (CPB). This study aimed to establish a model to predict the probability of postoperative AKI in patients undergoing cardiac surgery with CPB.

METHODS

We conducted a retrospective, multicenter study to analyze 1082 patients undergoing cardiac surgery under CPB. The least absolute shrinkage and selection operator regression model was used to optimize feature selection for the AKI model. Multivariable logistic regression analysis was applied to build a prediction model incorporating the feature selected in the previously mentioned model. Finally, we used multiple methods to evaluate the accuracy and clinical applicability of the model.

RESULTS

Age, gender, hypertension, CPB duration, intraoperative 5% bicarbonate solution and red blood cell transfusion, urine volume were identified as important factors. Then, these risk factors were created into nomogram to predict the incidence of AKI after cardiac surgery under CPB.

CONCLUSION

We developed a nomogram to predict the incidence of AKI after cardiac surgery. This model can be used as a reference tool for evaluating early medical intervention to prevent postoperative AKI.

The value of the ACEF II score in Chinese patients with elective and non-elective cardiac surgery

OBJECTIVE

To evaluate the value of the ACEF II score in predicting postoperative hospital death and acute kidney injury requiring dialysis (AKI-D) in Chinese patients.

METHODS

This retrospective study included adult patients who underwent cardiopulmonary bypass open heart surgery between January 2010 and December 2015 at Guangdong Provincial People's Hospital. ACEF II was evaluated to predict in-hospital death and AKI-D using the Hosmer-Lemeshow goodness of fit test for calibration and area under the receiver operating characteristic (ROC) curve for discrimination in non-elective and elective cardiac surgery.

RESULTS

A total of 9748 patients were included. Among them, 1080 underwent non-elective surgery, and 8615 underwent elective surgery. Mortality was 1.8% (177/9748). In elective surgery, the area under the ROC (AUC) of the ACEF II score was 0.704 (95% CI: 0.648-0.759), similar to the ACEF score of 0.709 (95% CI: 0.654-0.763). In non-elective surgery, the AUC of the ACEF II score was 0.725 (95% CI: 0.663-0.787), higher than the ACEF score (AUC = 0.625, 95% CI: 0.553-0.697). The incidence of AKI-D was 3.5% (345/9748). The AUC of the ACEF II score was 0.718 (95% CI: 0.687-0.749), higher than the ACEF score (AUC = 0.626, 95% CI: 0.594-0.658).

CONCLUSION

ACEF and ACEF II have poor discrimination ability in predicting AKI-D in non-elective surgery. The ACEF II and ACEF scores have the same ability to predict in-hospital death in elective cardiac surgery, and the ACEF II score is better in non-elective surgery. The ACEF II score can be used to assess the risk of AKI-D in elective surgery in Chinese adults.

Visceral protection in total arch replacement for aortic dissection: Effect of lower body hypothermia

OBJECTIVE

Optimal hypothermia strategy for total arch replacement in acute type A aortic dissection (ATAAD) is unclear. A higher temperature during circulatory arrest might reduce tolerance to ischemia for visceral organs. We sought to investigate the effect of hypothermia on visceral protection.

METHODS

From January 2010 to December 2019, 1138 consecutive patients underwent total arch replacement combined with frozen elephant trunk for acute type A aortic dissection. The data were retrospectively collected and analyzed. Visceral organ injury and visceral-related adverse outcomes were defined as acute renal failure or spinal cord injury or both. Multivariate logistic regression analysis and multivariate linear regression model were used.

RESULTS

The mean age of patient was 46.9 ± 10.0 years, with a male preponderance (79.6%). Operative mortality was 6.1% (69 patients). Spinal cord injury occurred in 55 (4.8%) patients and 133 (11.7%) patients had acute renal failure. In the multivariate logistic regression model, neither bladder temperature (odds ratio [OR] 0.971, 95% confidence interval [CI] 0.922-1.024, p = .278) nor circulatory arrest duration (OR 1.017, 95% CI 0.987-1.047, p = .267) significantly associated with visceral-related adverse outcomes. Female, lower limb malperfusion, age, cardiopulmonary bypass (CPB) duration and preoperative serum creatinine level were independent risk factors of visceral-related outcomes. There was a significant negative correlation between bladder temperature and CPB duration in multiple linear regression model (β = -3.67, p < .0001).

CONCLUSIONS

Bladder temperature had no effect on outcomes related to visceral protection under the premise of short circulatory arrest duration, but female gender, lower limb malperfusion, age, CPB duration, and preoperative serum creatinine level were independent risk factors. Bladder temperature negatively correlated to CPB duration.

Perioperative Management of the Patient at High-Risk for Cardiac Surgery-Associated Acute Kidney Injury

Acute kidney injury (AKI) is one of the most common major complications of cardiac surgery, and is associated with increased morbidity and mortality. Cardiac surgery-associated AKI has a complex, multifactorial etiology, including numerous factors such as primary cardiac dysfunction, hemodynamic derangements of cardiac surgery and cardiopulmonary bypass, and the possibility of a large volume of blood transfusion. There are no truly effective pharmacologic therapies for the management of AKI, and, therefore, anesthesiologists, intensivists, and cardiac surgeons must remain vigilant and attempt to minimize the risk of developing renal dysfunction. This narrative review describes the current state of the scientific literature concerning the specific aspects of cardiac surgery-associated AKI, and presents it in a chronological fashion to aid the perioperative clinician in their approach to this high-risk patient group. The evidence was considered for risk prediction models, preoperative optimization, and the intraoperative and postoperative management of cardiac surgery patients to improve renal outcomes.

Effects of changes in position, positive end-expiratory pressure and mean arterial pressure on renal, portal and hepatic Doppler ultrasound perfusion indices: a randomized crossover study in cardiac surgery patients

Point-of-care ultrasound perfusion indices can be used for detection of AKI and venous congestion. Patients in the postoperative- and intensive care units are frequently exposed to alternating treatment and loading conditions. We aimed to study the effects of changes in preload (patient positioning), positive end-expiratory pressure (PEEP) and afterload (phenylephrine) on renal, portal and hepatic ultrasound indices. We hypothesized that renal resistive index was not influenced by changes in PEEP and patient positioning. This was a single-site, randomized, crossover study. Patients above 18 years scheduled for elective open-heart surgery at Aarhus University Hospital, Denmark, were available for inclusion. Patients were randomized to a sequence of six combinations of PEEP and position in addition to an increase in mean arterial pressure by phenylephrine. Thirty-one patients participated in the study. Resistive index was influenced by positional change (P = 0.007), but not by change in PEEP (P = 0.50) (Table 1). Renal venous stasis index and portal pulsatility fraction increased in the raised legs position (P ≤ 0.019), but not with increases in PEEP. Renal venous flow pattern and hepatic venous flow pattern were affected by position (P ≤ 0.019), but not by PEEP. None of the ultrasound indices were significantly changed by infusion of phenylephrine. Doppler perfusion indices were significantly affected by changes in preload, but not by changes in PEEP or afterload. Although the changes in the Doppler ultrasound indices were significant, they were small in absolute numbers. Therefore, from a clinical perspective, the ultrasound indices were robust.Trial registration Registered at clinicaltrials.com, first posted online June 5th 2020, identifier: NCT04419662.

Association of serum anion gap and risk of long-term mortality in patients following coronary artery bypass grafting: A propensity score matching study

BACKGROUND

The present study aimed to explore the relationship between serum anion gap (AG) and long-term mortality in patients undergoing coronary artery bypass grafting (CABG).

METHODS

Clinical variables were extracted among patients undergoing CABG from Medical Information Mart for Intensive Care III (MIMIC III) database. The primary outcome was 4-year mortality following CABG. An optimal cut-off value of AG was determined by the receiver operating characteristic (ROC) curve. The Kaplan-Meier (K-M) analysis and multivariate Cox hazard analysis were performed to investigate the prognostic value of AG in long-term mortality after CABG. To eliminate the bias between different groups, propensity score matching (PSM) was conducted to validate the findings.

RESULTS

The optimal cut-off value of AG was 17.00 mmol/L. Then a total of 3162 eligible patients enrolled in this study were divided into a high AG group (≥17.00, n = 1022) and a low AG group (<17.00, n = 2,140). A lower survival rate was identified in the high AG group based on the K-M curve (p < .001). Compared with patients in the low AG group, patients in the high AG group had an increased risk of long-term mortality [1-year mortality: hazard ratio, HR: 2.309, 95% CI (1.672-3.187), p < .001; 2-year mortality: HR: 1.813, 95% CI (1.401-2.346), p < .001; 3- year mortality: HR: 1.667, 95% CI (1.341-2.097), p < .001; 4-year mortality: HR: 1.710, 95% CI (1.401-2.087), p < .001] according to multivariate Cox hazard analysis. And further validation of above results was consistent in the matched cohort after PSM.

CONCLUSIONS

The AG is an independent predictive factor for long-term all-cause mortality in patients following CABG, where a high AG value is associated with an increased mortality.

Postoperative central venous pressure is associated with acute kidney injury in patients undergoing coronary artery bypass grafting

Objective

The present study aimed to investigate the association of postoperative central venous pressure (CVP) with acute kidney injury (AKI) and mortality in patients undergoing coronary artery bypass grafting (CABG).

Method

Patients who underwent CABG in the MIMIC-III database were included and divided into two groups according to the optimal cutoff value of CVP for postoperative AKI determined by the receiver operating characteristic (ROC) curves. The association of CVP with AKI and mortality was determined by multivariate regression models. A 1:1 propensity score matching (PSM) was performed to balance the influence of potential confounding factors.

Results

A total of 3,564 patients were included and divided into High CVP group (CVP ≥ 10.9 mmHg) and Low CVP group (CVP &lt; 10.9 mmHg) according to the ROC analysis. Patients in High CVP group presented with higher AKI incidence (420 (28.2%) vs. 349 (16.8), p &lt; 0.001), in-hospital mortality (28 (1.9%) vs. 6 (0.3%), p &lt; 0.001) and 4-year mortality (149 (15.8%) vs. 162 (11.1%), p = 0.001). Multivariate regression model showed that CVP was an independent risk factor for the postoperative AKI (OR: 1.071 (1.035, 1.109), p &lt; 0.001), in-hospital mortality (OR: 1.187 (1.026, 1.373), p = 0.021) and 4-year mortality (HR: 1.049 (1.003, 1.096), p = 0.035). A CVP above 10.9 mmHg was significantly associated with about 50% higher risk of AKI (OR: 1.499 (1.231, 1.824), p &lt; 0.001). After PSM, 1004 pairs of score-matched patients were generated. The multivariate logistic model showed that patients with CVP ≥ 10.9 mmHg had a significantly higher risk of AKI (OR: 1.600 (1.268, 2.018), p &lt; 0.001) in the PSM subset. However, CVP, as a continuous or a dichotomic variable, was not independently associated with in-hospital mortality (OR: 1.202 (0.882, 1.637), p = 0.244; OR: 2.636 (0.399, 17.410), p = 0.314) and 4-year mortality (HR: 1.030 (0.974, 1.090), p = 0.297; HR: 1.262 (0.911, 1.749), p = 0.162) in the PSM dataset.

Conclusion

A mean CVP ≥ 10.9 mmHg within the first 24 h after CABG was independently associated with a higher risk of postoperative AKI.

Preoperative Ionized Magnesium Levels and Risk of Acute Kidney Injury After Cardiac Surgery

RATIONALE & OBJECTIVE

Although postoperative acute kidney injury (AKI) is a serious complication after cardiac surgery, preventive measures are limited. Despite the known association of preoperative low magnesium levels with cardiac surgery-related atrial fibrillation, the association between preoperative magnesium concentration and postoperative AKI has not been fully elucidated. This study evaluated the association between preoperative serum magnesium level and the development of AKI after cardiac surgery.

STUDY DESIGN

Retrospective observational cohort study.

SETTING & PARTICIPANTS

Patients aged≥18 years who underwent cardiac surgery at 2 South Korean tertiary hospitals between 2006 and 2020 were identified from medical records. Patients with missing information, an estimated glomerular filtration rate<15mL/min/1.73m², receiving maintenance dialysis, or a history of AKI treated by dialysis within 1 year before surgery were excluded.

EXPOSURE

Preoperative serum magnesium levels.

OUTCOME

Postoperative AKI within 48 hours after surgery, defined using the Acute Kidney Injury Network (AKIN) criteria, and dialysis-treated AKI within 30 days after surgery.

ANALYTICAL APPROACH

Multivariable logistic regression analysis.

RESULTS

Among the 9,766 patients (median age, 64.0 years; 60.1% male), postoperative AKI and dialysis-treated AKI were observed in 40.1% and 4.3% patients, respectively. Postoperative AKI was more prevalent in patients with lower serum magnesium levels (44.9%, 41.4%, 39.4%, and 34.8% in quartiles 1-4, respectively). Multivariable logistic regression analysis revealed that the odds ratios (ORs) for postoperative AKI were progressively larger across progressively lower quartiles of serum magnesium concentration (adjusted ORs of 1.53 [95% CI, 1.33-1.76], 1.29 [95% CI, 1.12-1.48], 1.15 [95% CI, 1.01-1.31] for quartiles 1-3, respectively, relative to quartile 4, P for trend<0.001). Preoperative hypomagnesemia (serum magnesium level<1.09mg/dL) was also significantly associated with AKI (adjusted OR, 1.39 [95% CI, 1.10-1.77]) and dialysis-treated AKI (adjusted OR, 1.67 [95% CI, 1.02-2.72]).

LIMITATIONS

Causality could not be evaluated in this observational study.

CONCLUSIONS

Lower serum magnesium levels were associated with a higher incidence of AKI in patients undergoing cardiac surgery.

Construction and validation of a nomogram for predicting survival in elderly patients with cardiac surgery

Background

In recent years, the number of elderly patients undergoing cardiac surgery has rapidly increased and is associated with poor outcomes. However, there is still a lack of adequate models for predicting the risk of death after cardiac surgery in elderly patients. This study sought to identify independent risk factors for 1-year all-cause mortality in elderly patients after cardiac surgery and to develop a predictive model.

Methods

A total of 3,752 elderly patients with cardiac surgery were enrolled from the Medical Information Mart for Intensive Care III (MIMIC-III) dataset and randomly divided into training and validation sets. The primary outcome was the all-cause mortality at 1 year. The Least absolute shrinkage and selection operator (LASSO) regression was used to decrease data dimensionality and select features. Multivariate logistic regression was used to establish the prediction model. The concordance index (C-index), receiver operating characteristic curve (ROC), and decision curve analysis (DCA) were used to measure the predictive performance of the nomogram.

Results

Our results demonstrated that age, sex, Sequential Organ Failure Assessment (SOFA), respiratory rate (RR), creatinine, glucose, and RBC transfusion (red blood cell) were independent factors for elderly patient mortality after cardiac surgery. The C-index of the training and validation sets was 0.744 (95%CI: 0.707-0.781) and 0.751 (95%CI: 0.709-0.794), respectively. The area under the curve (AUC) and decision curve analysis (DCA) results substantiated that the nomogram yielded an excellent performance predicting the 1-year all-cause mortality after cardiac surgery.

Conclusions

We developed a novel nomogram model for predicting the 1-year all-cause mortality for elderly patients after cardiac surgery, which could be an effective and useful clinical tool for clinicians for tailored therapy and prognosis prediction.

MMP 9-instructed assembly of bFGF nanofibers in ischemic myocardium to promote heart repair

Background: The only effective treatment for myocardial infarction (MI) is the timely restoration of coronary blood flow in the infarcted area, but further reperfusion exacerbates myocardial injury and leads to distal coronary no-reflow, which affects patient prognosis. Angiogenesis could be an important therapeutic strategy for re-establishing the blood supply to save the ischemic myocardium after MI. Basic fibroblast growth factor (bFGF) has been shown to promote angiogenesis. However, direct intravenous administration of bFGF is not a viable option given its poor half-life in vivo. Methods: Herein, we developed a peptide Lys-Lys-Pro-Leu-Gly-Leu-Ala-Gly-Phe-Phe (K2) to encapsulate bFGF to form bFGF@K2 micelle and proposed an enzyme-instructed self-assembly (EISA) strategy to deliver and slowly release bFGF in the ischemic myocardium. Results: The bFGF@K2 micelle exerted a stronger cardioprotective effect than free bFGF in a rat model of myocardial ischemia-reperfusion (MI/R). In vitro results revealed that the bFGF@K2 micelle could be cleaved by matrix metallopeptidase 9 (MMP-9) to yield bFGF@Nanofiber through amphipathic changes. In vivo experiments indicated that intravenous administration of bFGF@K2 micelle could lead to their restructuring into bFGF@Nanofiber and long term retention of bFGF in the ischemic myocardium of rat due to high expression of MMP-9 and assembly-induced retention (AIR) effect, respectively. Twenty-eight days after MI/R model establishment, bFGF@K2 micelle treatment significantly reduced fibrosis and improved cardiac function of the rats. Conclusion: We predict that our strategy could be applied in clinic for MI treatment in the future.

Strategies for post–cardiac surgery acute kidney injury prevention: A network meta-analysis of randomized controlled trials

Objects

Cardiac surgery is associated with acute kidney injury (AKI). However, the effects of various pharmacological and non-pharmacological strategies for AKI prevention have not been thoroughly investigated, and their effectiveness in preventing AKI-related adverse outcomes has not been systematically evaluated.

Methods

Studies from PubMed, Embase, and Medline and registered trials from published through December 2021 that evaluated strategies for preventing post–cardiac surgery AKI were identified. The effectiveness of these strategies was assessed through a network meta-analysis (NMA). The secondary outcomes were prevention of dialysis-requiring AKI, mortality, intensive care unit (ICU) length of stay (LOS), and hospital LOS. The interventions were ranked using the P-score method. Confidence in the results of the NMA was assessed using the Confidence in NMA (CINeMA) framework.

Results

A total of 161 trials (involving 46,619 participants) and 53 strategies were identified. Eight pharmacological strategies {natriuretic peptides [odds ratio (OR): 0.30, 95% confidence interval (CI): 0.19–0.47], nitroprusside [OR: 0.29, 95% CI: 0.12–0.68], fenoldopam [OR: 0.36, 95% CI: 0.17–0.76], tolvaptan [OR: 0.35, 95% CI: 0.14–0.90], N-acetyl cysteine with carvedilol [OR: 0.37, 95% CI: 0.16–0.85], dexmedetomidine [OR: 0.49, 95% CI: 0.32–0.76;], levosimendan [OR: 0.56, 95% CI: 0.37–0.84], and erythropoietin [OR: 0.62, 95% CI: 0.41–0.94]} and one non-pharmacological intervention (remote ischemic preconditioning, OR: 0.76, 95% CI: 0.63–0.92) were associated with a lower incidence of post–cardiac surgery AKI with moderate to low confidence. Among these nine strategies, five (fenoldopam, erythropoietin, natriuretic peptides, levosimendan, and remote ischemic preconditioning) were associated with a shorter ICU LOS, and two (natriuretic peptides [OR: 0.30, 95% CI: 0.15–0.60] and levosimendan [OR: 0.68, 95% CI: 0.49–0.95]) were associated with a lower incidence of dialysis-requiring AKI. Natriuretic peptides were also associated with a lower risk of mortality (OR: 0.50, 95% CI: 0.29–0.86). The results of a sensitivity analysis support the robustness and effectiveness of natriuretic peptides and dexmedetomidine.

Conclusion

Nine potentially effective strategies were identified. Natriuretic peptide therapy was the most effective pharmacological strategy, and remote ischemic preconditioning was the only effective non-pharmacological strategy. Preventive strategies might also help prevent AKI-related adverse outcomes. Additional studies are required to explore the optimal dosages and protocols for potentially effective AKI prevention strategies.

Renal Dysfunction in Patients with Left Ventricular Assist Device

Late-stage heart failure and renal dysfunction are often seen in conjunction. Cardiorenal syndrome (CRS) describes the complex interaction between the two disease states. Early literature described the pathophysiology of CRS as related only to reduced cardiac output and decreased renal perfusion. Recent literature suggests a more multifaceted mechanism. Left ventricular assist devices (LVAD), used as bridge-to-transplant and destination therapy in patients with heart failure, impact not only cardiac function but also renal function, especially in those patients with preoperative renal dysfunction. The mechanism by which LVAD implantation affects renal function is complex and understated in early literature. In this review, we discuss the pathogenesis of CRS, the impact of preoperative renal dysfunction in patients undergoing LVAD implantation, and the effect of LVAD implantation on postoperative renal function.

Protective effect of fluoxetine against oxidative stress induced by renal ischemia-reperfusion injury via the regulation of miR-450b-5p/Nrf2 axis

The present study was performed to assess the protective effect of fluoxetine (FLX) on renal ischemia-reperfusion injury (IRI) via the regulation of miR-450b-5p/Nrf2 axis in male rats. In vivo, these male rats were randomly divided into different treatment groups. The rats were administered with FLX (20 mg/kg, intraperitoneally) once daily for 3 days before operation. The pathomorphological changes of renal tissues were assessed by histological examination and Masson staining. In vitro, HK-2 cells were used to detect the activity by CCK-8 assay in Hypoxia/Reoxygenation (H/R) group and Hypoxia/Reoxygenation+Fluoxetine (H/R+FLX) group. In addition, the oxidative stress biomarkers were evaluated. Subsequently, Nrf2, NF-κB, and Nrf2-dependent antioxidant enzymes, were detected by Western blot assay. In vivo, the pathological changes and serological renal function were significantly relieved in the rats with the pre-treatment of FLX, compared to IRI group. After FLX stimulation, the expression levels of oxidative stress indices significantly decreased, while tissue antioxidant indices significantly increased, compared to IRI group. The differently expressed miRNAs on renal IRI in male rats were screened out by miRNA microarray, especially showing that miR-450b-5p was selected as the target miRNA. Following miR-450b-5p agomir injection, the pathological changes and oxidative stress biomarkers significantly aggravated, whether in IRI group or IRI+FLX group. Bioinformatics analysis and double-luciferase reporter assay demonstrated that miR-450b-5p directly targeted Nrf2. The expression level of NF-κB significantly increased, while the expression levels of Nrf2 and Nrf2-dependent antioxidant enzymes significantly decreased after miR-450b-5p agomir injection. Furthermore, the expression levels of Nrf2 and it-dependent antioxidant enzymes were apparently increased in ischemic kidney after the transfection of miR-450b-5p mimic+recombination protein Nrf2, as well as the decreased expression levels of intracellular ROS and iNOS. In vitro, FLX significantly increased HK-2 cell viability, and relieved H/R HK-2 cell oxidative injury via down-regulating ROS and iNOS. In addition, H/R-induced oxidative damage was recovered with miR-450b-5p mimic and recombination protein Nrf2. Consequently, FLX played an important protective role in renal IRI-induced oxidative damage by promoting antioxidation via targeting miR-450b-5p/Nrf2 axis.

Long-Term Consequences of Increased Activity of Urine Enzymes After Cardiac Surgery - A Prospective Observational Study

Introduction

Cardiac surgery associated AKI (CSA-AKI) complicates recovery and may be associated with a greater risk of developing chronic kidney disease and mortality. The aim of this study was to assess long-term clinical consequences of transient increased activity of urinary enzymes after cardiac surgery (CS).

Methods

An observational study was conducted in a group of 88 adult patients undergoing planned coronary artery bypass grafting (CABG), but all samples were obtained from 79 patients. The activity of urinary enzymes: N-acetyl-beta-glucosaminidase (NAG), arylsulfatase A (ASA) and beta-glucuronidase was evaluated in sequential urine samples. A comparative analysis of biochemical parameters was performed regarding the occurrence of acute kidney injury (AKI) defined by KIDGO at 24 hours, at day 30 and 5-years after the operation.

Results

During the first 24 hours after CS AKI was diagnosed in 13 patients. A comparison of the activity of urinary enzymes in pre-defined time-points showed significant differences for ASA and NAG (post OP-sample p < 0.028 and p < 0.022; POD 1 sample p < 0.004 and p < 0.001 respectively). No patient had any biochemical or clinical features of kidney failure at day 30. In the AKI group kidney failure was diagnosed in 36% of patients within 5 years of follow-up as opposed to 5% in the no AKI group. The activities of tubular enzymes in urine reflect a general injury of kidney tubules during and after the operation. However, they are not ideal biomarkers for prediction of the degree of kidney injury and further poor prognosis of CS-AKI.

Incremental value of preoperative right ventricular function in predicting moderate to severe acute kidney injury after heart transplantation

Background

Acute kidney injury (AKI) commonly occurs after heart transplantation (HTx), but its association with preoperative right ventricular (RV) function remains unknown. Consequently, we aimed to determine the predictive value of preoperative RV function for moderate to severe AKI after HTx.

Materials and methods

From 1 January 2016 to 31 December 2019, all the consecutive HTx recipients in our center were enrolled and analyzed for the occurrence of postoperative AKI staged by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Conventional RV function parameters, including RV fractional area change (RVFAC) and tricuspid annular plane systolic excursion (TAPSE), were obtained. The primary endpoint was moderate to severe AKI (the KDIGO stage 2 or 3). The secondary endpoints included the impact of AKI on intensive care unit (ICU) mortality, in-hospital mortality, and 1-year mortality.

Results

A total of 273 HTx recipients were included in the study. Postoperative AKI occurred in 209 (77%) patients, including 122 (45%) patients in stage 1 AKI, 49 (18%) patients in stage 2 AKI, and 38 (14%) patients in stage 3 AKI. Patients with higher AKI stage had lower baseline estimated glomerular filtration rate (eGFR), more frequent diabetes, higher right atrial pressure (RAP), longer cardiopulmonary bypass (CPB) duration, more perioperative red blood cell (RBC) transfusions, and worse preoperative RV function. A multivariate logistic regression model incorporating previous diabetes mellitus [odds ratio (OR): 2.21; 95% CI: 1.06–4.61; P = 0.035], baseline eGFR (OR: 0.99; 95% CI: 0.97–0.10; P = 0.037), RAP (OR: 1.05; 95% CI: 1.00–1.10; P = 0.041), perioperative RBC (OR: 1.18; 95% CI: 1.08–1.28; P < 0.001), and TAPSE (OR: 0.84; 95% CI: 0.79–0.91; P < 0.001) was established to diagnose moderate to severe AKI more accurately [the area under the curve (AUC) = 79.8%; Akaike information criterion: 274].

Conclusion

Preoperative RV function parameters provide additional predicting value over clinical and hemodynamic parameters, which are imperative for risk stratification in patients with HTx at higher risk of AKI.

Change in Oxidative Stress and Mitochondrial Dynamics in Response to Elevated Cold-Inducible RNA-Binding Protein in Cardiac Surgery-Associated Acute Kidney Injury

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a common yet serious complication that is closely related to cardiopulmonary bypass (CPB). Extracellular cold-inducible RNA-binding protein (eCIRP) can mediate aseptic inflammation and trigger intracellular oxidative stress. In the present study, expression of serum CIRP was significantly elevated post-CPB ( $785.0\pm 640.5$  pg/mL vs. $149.5\pm 289.1$  pg/mL, $P<0.001$ ) and was positively correlated with CPB duration ( $r=0.502$ , $P<0.001$ ). Patients with high expression of CIRP had higher risks of postoperative AKI than patients with low CIRP expression (OR: 1.67, 95% CI 1.04-2.68). In a rat CPB model, the serum CIRP concentration increased significantly after CPB. Similarly, the levels of Scr and BUN significantly increased 4 hours after CPB. KIM-1 and NGAL mRNA levels in the CPB group were 8.2 and 4.3 times higher than the sham group, respectively. In addition, the levels of inflammatory cell infiltration, oxidative stress, and apoptosis in the renal tissue of the CPB group were significantly higher compared to the sham group. The expression levels of serum inflammatory factors at 4 hours post-CPB were also increased. Administration of recombinant human CIRP protein promoted the expression of NADPH oxidase via the TLR-4/MyD88 pathway, aggravated intracellular oxidative stress, mediated mitochondrial dynamics disorder, and eventually increased apoptosis in HK-2 cells. However, the CIRP inhibitor C23 improved the CIRP-mediated oxidative stress and mitochondrial dysfunction in both rat and cell models. In summary, elevated CIRP could mediate oxidative stress and mitochondrial dynamics in the kidney to promote CSA-AKI.

Efficacy of N-acetylcysteine in Preventing Acute Kidney Injury and Major Adverse Cardiac Events After Cardiac Surgery: A Meta-Analysis and Trial Sequential Analysis

Background

The effect of N-acetylcysteine (NAC), an antioxidant, on preventing acute kidney injury (AKI) and major adverse cardiac events (MACE) remains controversial. Therefore, we conducted this meta-analysis and trial sequential analysis to evaluate its efficacy on cardiac surgery-related adverse events.

Methods

PubMed, Embase, and Cochrane Library were searched for relevant studies from inception to June 2021. We selected randomized controlled trials comparing NAC with controls in patients undergoing cardiac surgery.

Results

Twenty-five studies including 2,444 patients met the inclusion criteria. The pooled results showed that there was no significant difference in the incidence of AKI between the NAC and control groups [relative risk (RR) = 0.91, 95% confidence interval (CI) = 0.77, 1.08, P = 0.28], but the trial sequential analysis (TSA) could not confirm this result. No difference was observed in the need for renal replacement therapy (RRT), all-cause mortality, MACE, length of stay in the intensive care unit (ICU), and length of stay in the hospital. Results of subgroup analysis results showed that intravenous infusion instead of oral NAC could significantly reduce the incidence of AKI and arrhythmia (RR = 0.84, 95% CI = 0.71, 0.99, P = 0.03, I² = 3% and RR = 0.74, 95% CI = 0.61, 0.91, P = 0.004, I² = 48%, respectively).

Conclusion

Intravenous administration of NAC can reduce the incidence of AKI and arrhythmia in patients after cardiac surgery, but cannot reduce all-cause mortality, AMI, cardiac insufficiency, and the number of patients using RRT. Oral NAC has no significant effect on the outcomes of patients after cardiac surgery.

Evaluation of Renal Function after Partial Nephrectomy and Detection of Clinically Significant Acute Kidney Injury

Background and Objectives: Consequences of partial nephrectomy (PN), intraoperative hypotension (IOH) and postoperative neutrophil to lymphocyte ratio (NLR) may cause postoperative acute kidney injury (AKI) and in long-term-chronic kidney disease (CKD). Our study aimed to identify the AKI incidence after PN, to find clinically significant postoperative AKI and renal dysfunction, and to determine the predictor factors. Materials and Methods: A prospective observational study consisted of 91 patients who received PN with warm ischemia, and estimated preoperative glomerular filtration rate (eGFR) ≥ 60 mL/min and without abnormal albuminuria. Results: 38 (41.8%) patients experienced postoperative AKI. Twenty-one (24.1%) patients had CKD upstage after 1 year follow-up. Sixty-seven percent of CKD upstage patients had AKI 48 h after surgery and 11% after 2 months. All 15 (16.5%) patients with CKD had postoperative AKI. With IOH, OR 1.07, 95% CI 1.03−1.10 and p < 0.001, postoperative NLR after 48 h (OR 1.50, 95% CI 1.19−1.88, p < 0.001) was the major risk factor of AKI. In multivariate logistic regression analysis, the kidney’s resected part volume (OR 1.08, 95% CI 1.03−1.14, p < 0.001) and IOH (OR 1.10, 95% CI 1.04−1.15, p < 0.001) were retained as statistically significant prognostic factors for detecting postoperative renal dysfunction. The independent risk factor for clinically significant postoperative AKI was only IOH (OR, 1.06; p < 0.001). Only AKI with the CKD upstage group has a statistically significant effect (p < 0.0001) on eGFR 6 and 12 months after surgery. Conclusions: The presence of AKI after PN is not rare. IOH and NLR are associated with postoperative AKI. The most important predictive factor of postoperative AKI is an NLR of over 3.5. IOH is an independent risk factor for clinically significant postoperative AKI and together with kidney resected part volume effects postoperative renal dysfunction. Only clinically significant postoperative AKI influences the reduction of postoperative eGFR after 6 and 12 months.

Persistent vascular congestion in male spontaneously hypertensive rats contributes to delayed recovery of renal function following ischemia-reperfusion compared to females

Acute kidney injury (AKI) is a serious and frequent clinical complication with mortality rates up to 80%. Vascular congestion in the renal outer medulla occurs early after ischemia reperfusion (IR) injury, and congestion has been linked to worsened outcomes following IR. There is evidence implicating both male sex and preexisting hypertension as risk factors for poor outcomes following IR. The present study tested the hypothesis that male spontaneously hypertensive rats (SHR) have greater vascular congestion and impaired renal recovery following renal IR vs. female SHR and normotensive male Sprague-Dawley rats (SD). 13 wk old male and female SHR and SD were subjected to sham surgery or 30 minutes of warm bilateral ischemia followed by reperfusion. Rats were euthanized 24 hours or 7 days post-IR. IR increased renal injury in all groups vs. sham controls at 24 hours. At 7 days post-IR, injury remained elevated only in male SHR. Histological examination of SD and SHR kidneys 24 hours post-IR showed vascular congestion in males and females. Vascular congestion was sustained only in male SHR 7 days post-IR. To assess the role of vascular congestion on impaired recovery following IR, additional male and female SHR were pretreated with heparin (200 U/kg) prior to IR. Heparin pre-treatment reduced IR-induced congestion and improved renal function in male SHR 7 days post-IR. Interestingly, preventing increases in BP in male SHR did not alter sustained vascular congestion. Our data demonstrate that IR-induced vascular congestion is a major driving factor for impaired renal recovery in male SHR.

Metabolomic profiling demonstrates evidence for kidney and urine metabolic dysregulation in a piglet model of cardiac surgery-induced acute kidney injury

Acute kidney injury (AKI) is a common cause of morbidity after congenital heart disease surgery. Progress on diagnosis and therapy remains limited, however, in part due to poor mechanistic understanding and a lack of relevant translational models. Metabolomic approaches could help identify novel mechanisms of injury and potential therapeutic targets. In the present study, we used a piglet model of cardiopulmonary bypass with deep hypothermic circulatory arrest (CPB/DHCA) and targeted metabolic profiling of kidney tissue, urine, and serum to evaluate metabolic changes specific to animals with histological acute kidney injury. CPB/DHCA animals with acute kidney injury were compared with those without acute kidney injury and mechanically ventilated controls. Acute kidney injury occurred in 10 of 20 CPB/DHCA animals 4 h after CPB/DHCA and 0 of 7 control animals. Injured kidneys showed a distinct tissue metabolic profile compared with uninjured kidneys (R² = 0.93, Q² = 0.53), with evidence of dysregulated tryptophan and purine metabolism. Nine urine metabolites differed significantly in animals with acute kidney injury with a pattern suggestive of increased aerobic glycolysis. Dysregulated metabolites in kidney tissue and urine did not overlap. CPB/DHCA strongly affected the serum metabolic profile, with only one metabolite that differed significantly with acute kidney injury (pyroglutamic acid, a marker of oxidative stress). In conclusion, based on these findings, kidney tryptophan and purine metabolism are candidates for further mechanistic and therapeutic investigation. Urine biomarkers of aerobic glycolysis could help diagnose early acute kidney injury after CPB/DHCA and warrant further evaluation. The serum metabolites measured at this early time point did not strongly differentiate based on acute kidney injury.

NEW & NOTEWORTHY This project explored the metabolic underpinnings of postoperative acute kidney injury (AKI) following pediatric cardiac surgery in a translationally relevant large animal model of cardiopulmonary bypass with deep hypothermic circulatory arrest. Here, we present novel evidence for dysregulated tryptophan catabolism and purine catabolism in kidney tissue and increased urinary glycolysis intermediates in animals who developed histological AKI. These pathways represent potential diagnostic and therapeutic targets for postoperative AKI in this high-risk population.

Year in Review 2021: Noteworthy Literature in Cardiothoracic Critical Care

This year marked a number of milestones in critical care. As vaccines for the SARS-CoV-2 virus became widely available and were confirmed to be exceptionally effective against severe illness and hospitalization, we were then faced with new variants and the resource-intense responses necessary to combat them. Despite challenges new and old, we have persevered and continued to provide excellent care to our patients while pushing the boundaries of clinical research. This article is a collection of studies published in 2021 relevant to critical care, with a specific focus on cardiothoracic critical care. To ignore the impact of the COVID-19 pandemic would do a disservice to our colleagues, many of whom have made incredible breakthroughs in novel therapies to the coronavirus, and yet we present additional themes of delirium, acute kidney injury, lung transplant, advances in ECMO as well as biomarkers of sepsis.

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.

Prediction of acute kidney injury after cardiac surgery: model development using a Chinese electronic health record dataset

Background

Acute kidney injury (AKI) is a major complication following cardiac surgery that substantially increases morbidity and mortality. Current diagnostic guidelines based on elevated serum creatinine and/or the presence of oliguria potentially delay its diagnosis. We presented a series of models for predicting AKI after cardiac surgery based on electronic health record data.

Methods

We enrolled 1457 adult patients who underwent cardiac surgery at Nanjing First Hospital from January 2017 to June 2019. 193 clinical features, including demographic characteristics, comorbidities and hospital evaluation, laboratory test, medication, and surgical information, were available for each patient. The number of important variables was determined using the sliding windows sequential forward feature selection technique (SWSFS). The following model development methods were introduced: extreme gradient boosting (XGBoost), random forest (RF), deep forest (DF), and logistic regression. Model performance was accessed using the area under the receiver operating characteristic curve (AUROC). We additionally applied SHapley Additive exPlanation (SHAP) values to explain the RF model. AKI was defined according to Kidney Disease Improving Global Outcomes guidelines.

Results

In the discovery set, SWSFS identified 16 important variables. The top 5 variables in the RF importance matrix plot were central venous pressure, intraoperative urine output, hemoglobin, serum potassium, and lactic dehydrogenase. In the validation set, the DF model exhibited the highest AUROC (0.881, 95% confidence interval [CI] 0.831–0.930), followed by RF (0.872, 95% CI 0.820–0.923) and XGBoost (0.857, 95% CI 0.802–0.912). A nomogram model was constructed based on intraoperative longitudinal features, achieving an AUROC of 0.824 (95% CI 0.763–0.885) in the validation set. The SHAP values successfully illustrated the positive or negative contribution of the 16 variables attributed to the output of the RF model and the individual variable’s effect on model prediction.

Conclusions

Our study identified 16 important predictors and provided a series of prediction models to enhance risk stratification of AKI after cardiac surgery. These novel predictors might aid in choosing proper preventive and therapeutic strategies in the perioperative management of AKI patients.

Blood pressure variability during pediatric cardiac surgery is associated with acute kidney injury

BACKGROUND

Blood pressure variability (BPV), defined as the degree of variation between discrete blood pressure readings, is associated with poor outcomes in acute care settings. Acute kidney injury (AKI) is a common and serious postoperative complication of cardiac surgery with cardiopulmonary bypass (CPB) in children. No studies have yet assessed the association between intraoperative BPV during cardiac surgery with CPB and the development of AKI in children.

METHODS

A retrospective chart review of children undergoing cardiac surgery with CPB was performed. Intraoperative BPV was calculated using average real variability (ARV) and standard deviation (SD). Multiple regression models were used to examine the association between BPV and outcomes of AKI, hospital and intensive care unit (PICU) length of stay, and length of mechanical ventilation.

RESULTS

Among 231 patients (58% males, median age 8.6 months) reviewed, 51.5% developed AKI (47.9% Stage I, 41.2% Stage II, 10.9% Stage III). In adjusted models, systolic and diastolic ARV were associated with development of any stage AKI (OR 1.40, 95% CI 1.08-1.8 and OR 1.4, 95% CI 1.05-1.8, respectively). Greater diastolic SD was associated with longer PICU length of stay (β 0.94, 95% CI 0.62-1.2). When stratified by age, greater systolic ARV and SD were associated with AKI in infants ≤ 12 months, but there was no relationship in children > 12 months.

CONCLUSIONS

Greater BPV during cardiac surgery with CPB was associated with development of postoperative AKI in infants, suggesting that BPV is a potentially modifiable risk factor for AKI in this high-risk population.

Early post-operative PV-ACO2/CA-VO2 predicts subsequent acute kidney injury after complete repair of tetralogy of Fallot

BACKGROUND

Acute kidney injury is a severe complication following complete repair of tetralogy of Fallot. Anaerobic metabolism is believed to contribute to the development of acute kidney injury. The ratio of central venous to arterial carbon dioxide tension to arterio-venous oxygen content (PV-ACO2/CA-VO2) has been proposed as a surrogate for respiratory quotient and an indicator of tissue oxygenation. We hypothesised that a small increase of PV-ACO2/CA-VO2 might have superior discrimination ability in subsequent acute kidney injury prediction.

METHODS

This study is retrospective and single-centre design study. The study population consisted of 61 children with tetralogy of Fallot that underwent a complete surgical repair between July 2017 and January 2021. Baseline characteristics and intra-operative parameters were collected through a retrospective chart review. PV-ACO2/CA-VO2 was collected within 12 hours of surgical completion. Acute kidney injury was defined according to the criteria established by the Kidney Disease: Improving Global Outcomes group. Univariate and logistic regression analyses were performed to determine risk factors for acute kidney injury.

RESULTS

Of the 61 patients, 20 (32.8%) developed acute kidney injury. Multivariate logistic analyses showed that age, height, haematocrit, and Pv-aCO2/Ca-vO2 were independently associated with the development of acute kidney injury. The addition of Pv-aCO2/Ca-vO2 to the model significantly increased model discrimination [AUROC 0.939 (95% CI 0.894-0.984) and AUROC 0.922 (95% CI 0.869-0.975), respectively].

CONCLUSIONS

The increase of PV-ACO2/CA-VO2 could improve the predictive ability for subsequent development of acute kidney injury in children with tetralogy of Fallot.

Early and late outcomes of surgical aortic valve replacement with sutureless and rapid-deployment valves versus transcatheter aortic valve implantation: Meta-analysis with reconstructed time-to-event data of matched studies

Sutureless/rapid-deployment (SURD) valves are options different from the stented prostheses included in the pivotal trials comparing surgical aortic valve replacement (AVR) and transcatheter aortic valve implantation (TAVI). We performed a meta-analysis with reconstructed time-to-event data of matched studies published by November 2021 to compare SURD-AVR and TAVI. Primary endpoints were 30-day mortality and overall survival in the follow-up. Secondary endpoints included: 30-day stroke, acute kidney injury (AKI), major bleeding, permanent pacemaker implantation (PPI), paravalvular leak (PVL), prosthesis-patient mismatch (PPM), postoperative aortic valve area (AVA), and mean gradients. Ten studies met our eligibility criteria, including a total of 5134 patients (2567 underwent SURD-AVR and 2567 underwent TAVI). Pooled risk of 30-day mortality did not favor any group (odds ratio [OR]: 0.69; 95% confidence interval [CI]: 0.31-1.53; p = 0.360). Patients undergoing SURD-AVR had lower risk of PVL (OR: 0.09; 95% CI: 0.05-0.17; p < 0.001). No statistically significant differences were observed for 30-day stroke, AKI, major bleeding, PPI, PPM, and postoperative AVA. In the follow-up, we observed a higher risk of mortality (hazard ratio: 1.74; 95% CI: 1.26-2.40; p < 0.001) with TAVI. Patients who underwent SURD-AVR experienced better survival, however, the interpretation of these results warrant caution due to the fact that SURD-AVR patients tended to be younger than TAVI patients. Structural heart surgeons and interventional cardiologists should consider initial risk and life expectancy when referring patients for one approach over the other.

A Novel Radiomics-Based Machine Learning Framework for Prediction of Acute Kidney Injury-Related Delirium in Patients Who Underwent Cardiovascular Surgery

Acute kidney injury (AKI) can be caused by multiple etiologies and is characterized by a sudden and severe decrease in kidney function. Understanding the independent risk factors associated with the development of AKI and its early detection can refine the risk management and clinical decision-making of high-risk patients after cardiovascular surgery. A retrospective analysis was performed in a single teaching hospital between December 1, 2019, and December 31, 2020. The diagnostic performance of novel biomarkers was assessed using random forest, support vector machine, and multivariate logistic regression. The nomogram from multivariate analysis of risk factors associated with AKI indicated that only LVEF, red blood cell input, and ICUmvat contribute to AKI differentiation and that the difference is statistically significant (P < 0.05). Seven radiomics biomarkers were found among 65 patients to be highly correlated with AKI-associated delirium. The importance of the variables was determined using the multilayer perceptron model; fivefold cross-validation was applied to determine the most important delirium risk factors in radiomics of the hippocampus. Finally, we established a radiomics-based machine learning framework to predict AKI-induced delirium in patients who underwent cardiovascular surgery.

Association Between the Presence of Pulmonary Hypertension Before Cardiovascular Surgery and the Nephroprotective Effect of Carperitide: A Retrospective Cohort Study

Introduction

We hypothesized that the nephroprotective and diuretic effects of carperitide are effective in patients with pulmonary hypertension. We examined the presence of preoperative pulmonary hypertension and the effects of carperitide.

Methods

In this retrospective cohort study, we included patients aged 20 years or older who received carperitide during cardiovascular surgery and were admitted to the postoperative intensive care unit. We used hospital data from March 2019 to September 2021. The outcomes were the incidence of acute kidney injury, the number of patients using renal replacement therapy in the intensive care unit, urine volume in the first 24 hours after surgery, and the difference in serum creatinine concentrations between before and after surgery. After adjusting for confounding factors by multivariate analysis, we compared the difference in outcomes with and without preoperative pulmonary hypertension (systolic pulmonary artery pressure ≥36 mmHg).

Results

The study included 244 patients, with 72 (29.5%) in the pulmonary hypertension group and 172 (70.5%) in the control group. Acute kidney injury occurred in eight (11.1%) patients in the pulmonary hypertension group and in 18 (10.5%) patients in the control group, with no significant difference by logistic regression analysis (odds ratio 1.40, 95% confidence interval 0.54-3.62, p=0.49). Additionally, the use of renal replacement therapy, urine volume at 24 hours postoperatively, and the difference in serum creatinine concentrations were not different between the two groups.

Conclusions

Our results suggest that the effect of carperitide during cardiovascular surgery is not affected by the presence or absence of pulmonary hypertension.

Acute kidney injury following major emergency abdominal surgery – a retrospective cohort study based on medical records data

Background

Acute Kidney Injury (AKI) is a frequent and serious postoperative complication in trauma or critically ill patients in the intensive care unit. We aimed to estimate the risk of AKI following major emergency abdominal surgery and the association between AKI and 90-day postoperative mortality.

Methods

In this retrospective cohort study, we included patients undergoing major emergency abdominal surgery at the Department of Surgery, Zealand University Hospital, Denmark, from 2010 to 2016. The primary outcome was the occurrence of AKI within postoperative day seven (POD7). AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO)-criteria. The risk of AKI was analysed with a multivariable logistic regression. The association between AKI and 90-day mortality was analysed with a multivariable survival analysis.

Results

In the cohort, 122 out of 703 (17.4%) surgical patients had AKI within POD7. Of these, 82 (67.2%) had AKI stage 1, 26 (21.3%) had AKI stage 2, and 14 (11.5%) had AKI stage 3. Fifty-eight percent of the patients who developed postoperative AKI did so within the first 24 h of surgery. Ninety-day mortality was significantly higher in patients with AKI compared with patients without AKI (41/122 (33.6%) versus 40/581 (6.9%), adjusted hazard ratio 4.45 (95% confidence interval 2.69–7.39, P < 0.0001)), and rose with increasing KDIGO stage. Pre-existing hypertension and intraoperative peritoneal contamination were independently associated with the risk of AKI.

Conclusions

The risk of AKI is high after major emergency abdominal surgery and is independently associated with the risk of death within 90 days of surgery.

Mice with Established Diabetes Show Increased Susceptibility to Renal Ischemia/Reperfusion Injury: Protection by Blockade of Jnk or Syk Signaling Pathways

Patients with diabetes are at an increased risk for acute kidney injury (AKI) after renal ischemia/reperfusion injury (IRI). However, there is a lack preclinical models of IRI in established diabetes. The current study characterized renal IRI in mice with established diabetes and investigated potential therapies. Diabetes was induced in C57BL/6J mice by low-dose streptozotocin injection. After 7 weeks of sustained diabetes, mice underwent 13 minutes of bilateral renal ischemia and were euthanized after 24 hours of reperfusion. Age-matched, nondiabetic controls underwent the same surgical procedure. Renal IRI induced two- and sevenfold increases in plasma creatinine level in nondiabetic and diabetic mice, respectively (P < 0.001). Kidney damage, as indicated by histologic damage, tubular cell death, tubular damage markers, and inflammation, was more severe in the diabetic IRI group. The diabetic IRI group showed greater accumulation of spleen tyrosine kinase (Syk)-expressing cells, and increased c-Jun N-terminal kinase (Jnk) signaling in tubules compared to nondiabetic IRI. Prophylactic treatment with a Jnk or Syk inhibitor substantially reduced the severity of AKI in the diabetic IRI model, with differential effects on neutrophil infiltration and Jnk activation. In conclusion, established diabetes predisposed mice to renal IRI-induced AKI. Two distinct proinflammatory pathways, JNK and SYK, were identified as potential therapeutic targets for anticipated AKI in patients with diabetes.

Experimental models of acute kidney injury for translational research

Preclinical models of human disease provide powerful tools for therapeutic discovery but have limitations. This problem is especially apparent in the field of acute kidney injury (AKI), in which clinical trial failures have been attributed to inaccurate modelling performed largely in rodents. Multidisciplinary efforts such as the Kidney Precision Medicine Project are now starting to identify molecular subtypes of human AKI. In addition, over the past decade, there have been developments in human pluripotent stem cell-derived kidney organoids as well as zebrafish, rodent and large animal models of AKI. These organoid and AKI models are being deployed at different stages of preclinical therapeutic development. However, the traditionally siloed, preclinical investigator-driven approaches that have been used to evaluate AKI therapeutics to date rarely account for the limitations of the model systems used and have given rise to false expectations of clinical efficacy in patients with different AKI pathophysiologies. To address this problem, there is a need to develop more flexible and integrated approaches, involving teams of investigators with expertise in a range of different model systems, working closely with clinical investigators, to develop robust preclinical evidence to support more focused interventions in patients with AKI.

Postoperative Serum Creatinine Serves as a Prognostic Predictor of Cardiac Surgery Patients

Background

Serum creatinine, an important diagnostic indicator for acute kidney injury (AKI), was considered to be a risk factor for cardiovascular disease. This study aimed to investigate the significance of postoperative serum creatinine in predicting the prognosis of cardiac surgery patients.

Methods

The Medical Information Mart for Intensive Care III (MIMIC-III) database was used to extract the clinical data. Adult (≥18 years) cardiac surgery patients in the database were enrolled. The correlation of postoperative serum creatinine with lengths of intensive care unit (ICU) stay was analyzed with Spearman correlation, and the association of postoperative serum creatinine with hospital mortality was analyzed with chi-square tests. Multivariable logistic regression was used to identify postoperative serum creatinine as an independent prognostic factor for hospital mortality.

Results

A total of 6,001 patients were enrolled in our study, among whom, 108 patients (1.8%) died in the hospital. Non-survivors had much higher postoperative serum creatinine levels (initial: 0.8 vs. 1.2 mg/dl, P < 0.001; maximum: 1.1 vs. 2.8 mg/dl, P < 0.001; minimum: 0.8 vs.1.1 mg/dl, P < 0.001). Positive correlations were observed between postoperative serum creatinine (P < 0.001) and lengths of ICU stay. For all models, postoperative initial creatinine, postoperative maximum creatinine, and postoperative minimum creatinine were all positively associated with hospital mortality (all P < 0.001). The predictive performance of postoperative serum creatinine was moderately good (area under the curve (AUC) for initial creatinine = 0.7583; AUC for maximum creatinine = 0.8413; AUC for minimum creatinine = 0.7063).

Conclusions

This study demonstrated the potential to use postcardiac surgery serum creatinine as an outcome indicator.

Risk Factors for Acute Kidney Injury Following Cardiac Surgery and Performance of Leicester Score in a Spanish Cohort

The incidence of acute kidney injury following cardiac surgery (CSA-AKI) is up to 30%, and it places patients at an increased risk of death. The Leicester score (LS) is a new score that predicts CSA-AKI of any stage with better discrimination compared to previous scores. The aim of this study was to identify risk factors for CSA-AKI and to assess the performance of LS. A unicentric retrospective study of patients that required cardiac surgery with cardio-pulmonary bypass (CPB) in 2015 was performed. The inclusion criteria were patients over 18 years old who were operated on for cardiac surgery (valve substitution (VS), Coronary Artery Bypass Graft (CABG), or a combination of both procedures and requiring CPB). CSA-AKI was defined with the Kidney Disease Improving Global Outcomes (KDIGO) criteria. In the multivariate analysis, hypertension (odds ratio 1.883), estimated glomerular filtration rate (EGFR) <60 mL/min (2.365), and peripheral vascular disease (4.66) were associated with the outcome. Both discrimination and calibration were better when the LS was used compared to the Cleveland Clinic Score and Euroscore II, with an area under the curve (AUC) of 0.721. In conclusion, preoperative hypertension in patients with CKD with or without peripheral vasculopathy can identify patients who are at risk of CSA-AKI. The LS was proven to be a valid score that could be used to identify patients who are at risk and who could benefit from intervention studies.

Gelatin and the risk of acute kidney injury after cardiac surgery

BACKGROUND

Gelatin has been used as a plasma volume expander because of its ability to preserve intravascular volume more effectively than crystalloids. However, gelatin may have detrimental effects on kidney function and increase the risk of acute kidney injury (AKI).

METHOD

We investigated by retrospective analysis of prospectively collected data whether the administration of 4% succinyl gelatin is associated with an increased risk of AKI after cardiac surgery. We compared two propensity score-matched groups of 1,187 patients (crystalloid group and gelatin group).

RESULTS

The incidence of AKI was similar in both groups (gelatin 21% and crystalloid 20%) (p = 0.414). The incidence of moderate AKI (8% vs. 6%) was higher in the gelatin group, but there was no difference in mild or severe AKI. Postoperative serum creatine on the first (70 vs. 70 μmol L^-1 , p = 0.689) or fourth (71 vs. 70, p = 0.313) postoperative day was similar between groups and there was no difference in the need for new renal replacement therapy (p = 0.999). Patients in the gelatin group received less crystalloids (2080 ml vs. 4130 ml, p = 0.001) and total fluids (3760 ml vs. 4180 ml, p = 0.001), their fluid balance was less positive (p = 0.001) and they required less vasoactive and inotropic medication (p = 0.001). Gelatin was not associated with increased mortality compared to the crystalloid group.

CONCLUSION

Gelatin was not associated with AKI after cardiac surgery.

Suppressing Syndecan-1 Shedding to Protect Against Renal Ischemia/Reperfusion Injury by Maintaining Polarity of Tubular Epithelial Cells

ABSTRACT

Syndecan-1 (SDC-1), a type of heparan sulfate proteoglycan on the surface of epithelial cells, is involved in maintaining cell morphology. Loss of cell polarity constitutes the early stage of ischemic acute kidney injury (AKI). This study investigated the role of SDC-1 shedding in I/R-induced AKI and the underlying mechanisms. Levels of the shed SDC-1 in the serum were measured with ELISA 12 and 24 h after reperfusion in renal I/R model mice. Na+/K+-ATPase-α1 expression was evaluated using western blotting in vivo and immunofluorescence in hypoxia/reoxygenation (H/R) cysts. Renal tubular epithelial cell apoptosis was measured using TUNEL in vivo and flow cytometry in vitro. Furthermore, plasma syndecan-1 (pSDC-1) levels were measured in patients at the time of anesthesia resuscitation after cardiac surgery. We found that shed SDC-1 levels increased and Na+/K+-ATPase-α1 expression decreased after H/R in the three-dimensional (3D) tubular model, and this state was exacerbated with extended period of hypoxia. After the inhibition of SDC-1 shedding by GM6001, SDC-1 and Na+/K+-ATPase-α1 expression was restored, while H/R-induced apoptosis was decreased. In vivo, SDC-1 shedding was induced by renal I/R and was accompanied with a loss of renal tubular epithelial cell polarity and increased apoptosis. GM6001 pretreatment protected against I/R injury by alleviating the disruption of cell polarity and apoptosis. pSDC-1 levels were significantly higher in AKI patients than in non-AKI patients. ROC curve showed that the accuracy of pSDC-1 for AKI prediction was 0.769. In conclusion, inhibition of I/R-induced SDC-1 shedding could contribute to renal protection by restoring the loss of cell polarity and alleviating apoptosis in tubular epithelial cells.

DsbA-L interacts with VDAC1 in mitochondrion-mediated tubular cell apoptosis and contributes to the progression of acute kidney disease

BACKGROUND

we demonstrated that disulfide-bond A oxidoreductase-like protein (DsbA-L) was involved in the progression of renal fibrosis. However, the precise function of DsbA-L in acute kidney injury (AKI), and the mechanisms involved, have yet to be elucidated.

METHODS

We illustrate the DsbA-L interacted with VDAC1 by co-IP (co-immunoprecipitation) in vitro and vivo, and found the interaction parts of them by mutation experiment. The above findings were verified by co-localization of them. In addition, we constructed the two model of PT-DsbA-L and VDAC1 KO mice to verify the function of DsbA-L and VDAC1 in models of VAN, CLP and I/R-induced AKI.

FINDINGS

The PT-DsbA-L-KO mice showed amelioration of I/R, VAN-, and CLP-induced AKI progression via the downregulation of VDAC1. Finally, we confirmed these changes in signal molecules by examining in HK-2 cells and kidney biopsies taken from patients with ischemic or acute interstitial nephritis (AIN)-induced AKI. Mechanistically, DsbA-L interacted with amino acids 9-13 and 22-27 of VDAC1 in the mitochondria of BUMPT cells to induce renal cell apoptosis and mitochondrial injury.

INTERPRETATION

This work suggested that DsbA-L, located in the proximal tubular cells, drives the progression of AKI, by directly upregulating the levels of VDAC1.Running Title: The role of DsbA-L in AKI FUNDING: National Natural Science Foundation of China, a grant from Key Project of Hunan provincial science and technology innovation, Department of Science and Technology of Hunan Province project of International Cooperation and Exchanges, Changsha Science and Technology Bureau project, Natural Science Foundation of Hunan Province, Fundamental Research Funds for the Central Universities of Central South University, Hunan Provincial Innovation Foundation For Postgraduate China Hunan Provincial Science and Technology Department.

Preoperative Creatinine Clearance and Mortality of Elective Cardiac Surgery in Hospitalization: A Secondary Analysis

Objective

It has been reported that poor renal function before surgery is related to poor prognosis. However, there is no specific discussion on the ideal value of preoperative creatinine clearance. Consequently, our primary goal is to explore the correlation between baseline creatinine clearance and short-term mortality after cardiac surgery.

Methods

We conducted a secondary data analysis based on a French cardiac surgery cohort. The cohort included 6,889 participants in a Paris university hospital from December 2005 to December 2012. The exposure variable and outcome variable used in this secondary analysis were the preoperative creatinine clearance rate and postoperative hospital mortality. Multivariate logistic regression and generalized additive models were employed.

Results

The nonlinear relationship between the preoperative creatinine clearance rate and postoperative death was observed in this study. The preoperative creatinine clearance rate was negatively correlated with postoperative mortality in the range of 8.9–78.5 in patients younger than 80 years old (odds ratio = 0.98, 95% confidence interval 0.97–0.98, in Cockcroft Gault formulae). However, this effect characteristics reaches saturation after the preoperative creatinine clearance rate exceeds 78.5 (odds ratio = 0.99, 95% confidence interval 0.98–1.00, CG). In patients with history of thromboembolic event and coronary artery disease, the saturation effect were 30.8 mL.min⁻¹ (CG) and 56.6 mL.min⁻¹(CG).

Conclusion

In the range of 8.9–78.5 (Cockcroft), an increase in preoperative creatinine clearance is associated with a decrease in postoperative mortality with patients younger than 80 years old. In patients with a history of embolism and coronary artery disease, the cut-off points of the reduction in preoperative creatinine clearance associated with a increase in postoperative mortality are 30.8 mL.min⁻¹ and 56.6 mL.min⁻¹.

Analysis of Risk Factors for Perioperative Acute Kidney Injury and Management Strategies

Acute kidney injury (AKI) is a serious clinical syndrome, and one of the common comorbidities in the perioperative period. AKI can lead to complications in surgical patients and is receiving increasing attention in clinical workup. In recent years, the analysis of perioperative risk factors has become more in-depth and detailed. In this review, the definition, diagnosis, and pathophysiological characteristics of perioperative AKI are reviewed, and the main risk factors for perioperative AKI are analyzed, including advanced age, gender, certain underlying diseases, impaired clinical status such as preoperative creatinine levels, and drugs that may impair renal function such as non-steroidal anti-inflammatory drugs (NASIDs), ACEI/ARB, and some antibiotics. Injectable contrast agents, some anesthetic drugs, specific surgical interventions, anemia, blood transfusions, hyperglycemia, and malnutrition are also highlighted. We also propose potential preventive and curative measures, including the inclusion of renal risk confirmation in the preoperative assessment, minimization of intraoperative renal toxin exposure, intraoperative management and hemodynamic optimization, remote ischemic preadaptation, glycemic control, and nutritional support. Among the management measures, we emphasize the need for careful perioperative clinical examination, timely detection and management of AKI complications, administration of dexmedetomidine for renal protection, and renal replacement therapy. We aim that this review can further increase clinicians' attention to perioperative AKI, early assessment and intervention to try to reduce the risk of AKI.

Dextran-based priming solution during cardiopulmonary bypass attenuates renal tubular injury-A secondary analysis of randomized controlled trial in adult cardiac surgery patients

BACKGROUND

Acute kidney injury (AKI) is a well-known complication after cardiac surgery and cardiopulmonary bypass (CPB). In the present secondary analysis of a blinded randomized controlled trial, we evaluated the effects of a colloid-based versus a conventional crystalloid-based prime on tubular injury and postoperative renal function in patients undergoing cardiac surgery with CPB.

METHODS

Eighty-four adult patients undergoing cardiac surgery with CPB were randomized to receive either a crystalloid- or colloid- (dextran 40) based CPB priming solution. The crystalloid solution was based on Ringer-Acetate plus mannitol. The tubular injury biomarker, N-acetyl-b-D-glucosaminidase (NAG), serum creatinine and diuresis were measured before, during and after CPB. The incidence of AKI was assessed according to the KDIGO criteria.

RESULTS

The urinary-NAG/urinary-creatinine ratio rose in both groups during and after CPB, with a more pronounced increase in the crystalloid group (p = .038). One hour after CPB, the urinary-NAG/urinary-creatinine ratio was 88% higher in the crystalloid group (4.7 ± 6.3 vs. 2.5 ± 2.7, p = .045). Patients that received the dextran 40-based priming solution had a significantly lower intraoperative diuresis (p < .001) compared to the crystalloid group. The incidence of AKI was 18% in the colloid and 22% in the crystalloid group (p = .66). Postoperative serum creatinine did not differ between groups.

CONCLUSIONS

In patients undergoing cardiac surgery with CPB, colloid-based priming solution (dextran 40) induced less renal tubular injury compared to a crystalloid-based priming solution. Whether a colloid-based priming solution will improve renal outcome in high-risk cardiac surgery, or not, needs to be evaluated in future studies on higher risk cardiac surgery patients.