Influence of acute kidney injury on short- and long-term outcomes in patients undergoing cardiac surgery: risk factors and prognostic value of a modified RIFLE classification. Crit Care. 2013;17:R293. [PMID: 24330769 PMCID: PMC4056889 DOI: 10.1186/cc13159]

Association of Postoperative Serum Lactate Levels with Acute Kidney Injury in Mexican Patients Undergoing Cardiac Surgery

Acute kidney injury (AKI) is a highly prevalent and a critical complication of cardiac surgery (CS). Serum lactate (sLac) levels have consistently shown an association with morbimortality after CS. We performed a cross-sectional study including 264 adult patients that had a cardiac surgery between January and December 2020. Logistic regression analysis was performed to determine factors associated with AKI development. We measured the postoperative levels of sLac for all participants immediately after CS (T0) and at 4 h (T4) after the surgical intervention. A linear regression model was used to identify the factors influencing both sLac metrics. We identified four risk predictors of AKI; one was preoperative (atrial fibrillation), one intraoperative (cardiopulmonary bypass time), and two were postoperative (length of hospital stay and postoperative sLac). T0 and T4 sLac levels were higher among CS-AKI patients than in Non-CS-AKI patients. Postoperative sLac levels were significant independent predictors of CSA-AKI, and sLac levels are influenced by length of hospital stay, the number of transfused packed red blood cells, and the use of furosemide in CS-AKI patients. These findings may facilitate the earlier identification of patients susceptible to AKI after CS.

Prospective randomized double-blind study to evaluate the superiority of Vasopressin versus Norepinephrine in the management of the patient at renal risk undergoing cardiac surgery with cardiopulmonary bypass (NOVACC trial)

BACKGROUND

Cardiac surgery-associated acute kidney injury (CS-AKI) affects up to 30% of patients, increasing morbidity and healthcare costs. This condition results from complex factors like ischemia-reperfusion injury and renal hemodynamic changes, often exacerbated by surgical procedures. Norepinephrine, commonly used in cardiac surgeries, may heighten the risk of CS-AKI. In contrast, vasopressin, a noncatecholaminergic agent, shows potential in preserving renal function by favorably affecting renal hemodynamic. Preliminary findings, suggest vasopressin could reduce the incidence of CS-AKI compared to norepinephrine. Additionally, vasopressin is linked to a lower incidence of postoperative atrial fibrillation, another factor contributing to longer hospital stays and higher costs. This study hypothesizes that vasopressin could effectively reduce CS-AKI occurrence and severity by optimizing renal perfusion during cardiac surgeries.

STUDY DESIGN

The NOVACC trial (NCT05568160) is a multicenter, randomized, double blinded superiority-controlled trial testing the superiority of vasopressin over norepinephrine in patients scheduled for cardiac surgery with cardiopulmonary bypass (CPB). The primary composite end point is the occurrence of acute kidney injury and death. The secondary end points are neurological, cardiologic, digestive, and vasopressor related complications at day 7, day 30, day 90, hospital and intensive care unit lengths of stay, medico-economic costs at day 90.

CONCLUSION

The NOVACC trial will assess the effectiveness of vasopressin in cardiac surgery with CPB in reducing acute kidney injury, mortality, and medical costs.

CLINICAL TRIAL REGISTRATION

NCT05568160.

Surgical Aortic Valve Replacement and Renal Dysfunction: From Acute Kidney Injury to Chronic Disease

Background: Surgical aortic valve replacement (SAVR) is often complicated by acute kidney injury (AKI). Identifying patients at risk of AKI is important to start nephroprotective strategies or renal replacement therapy (RRT). This study investigated the incidence and risk factors of post-operative AKI in SAVR patients. Chronic kidney disease (CKD) developed in the post-cardiac-surgery follow-up period was also assessed. Methods: A total of 462 SAVR patients were retrospectively enrolled. The primary endpoint was the occurrence rate of AKI after surgery. Kidney recovery, during two planned outpatient clinic nephrological visits within 12 months after the surgery, was assessed. Results: A total of 76 patients experienced an AKI event. A Kaplan-Meier analysis revealed that subjects with CKD stage IV had a time to progression of 2.7 days, compared to patients with stages I-II, who were characterized by the slowest progression time, >11.2 days. A Cox regression indicated that CKD stages predicted a higher risk of AKI independently of other variables. During their ICU stay, 23 patients died, representing 5% of the population, most of them requiring RRT during their ICU stay. A severe CKD before the surgery was closely related to perioperative mortality. During the follow-up period, 21 patients with AKI worsened their CKD stage. Conclusions: AKI represents a common complication for SAVR patients in the early post-operative period, prolonging their ICU stay, with negative effects on survival, especially if RRT was required. Pre-operative CKD >3 stage is an independent risk factor for AKI in patients undergoing SAVR.

Machine learning in cardiac surgery: a narrative review

Background and Objective

Machine learning (ML) is increasingly being utilized to provide data driven solutions to challenges in medicine. Within the field of cardiac surgery, ML methods have been employed as risk stratification tools to predict a variety of operative outcomes. However, the clinical utility of ML in this domain is unclear. The aim of this review is to provide an overview of ML in cardiac surgery, particularly with regards to its utility in predictive analytics and implications for use in clinical decision support.

Methods

We performed a narrative review of relevant articles indexed in PubMed since 2000 using the MeSH terms "Machine Learning", "Supervised Machine Learning", "Deep Learning", or "Artificial Intelligence" and "Cardiovascular Surgery" or "Thoracic Surgery".

Key Content and Findings

ML methods have been widely used to generate pre-operative risk profiles, consistently resulting in the accurate prediction of clinical outcomes in cardiac surgery. However, improvement in predictive performance over traditional risk metrics has proven modest and current applications in the clinical setting remain limited.

Conclusions

Studies utilizing high volume, multidimensional data such as that derived from electronic health record (EHR) data appear to best demonstrate the advantages of ML methods. Models trained on post cardiac surgery intensive care unit data demonstrate excellent predictive performance and may provide greater clinical utility if incorporated as clinical decision support tools. Further development of ML models and their integration into EHR's may result in dynamic clinical decision support strategies capable of informing clinical care and improving outcomes in cardiac surgery.

The effect of ulinastatin on acute kidney injury in patients undergoing off-pump cardiac bypass surgery

BACKGROUND

Ulinastatin, an anti-inflammatory and antioxidant trypsin inhibitor, has shown potential in mitigating acute kidney injury (AKI) and reducing serum creatinine levels after various surgeries. This retrospective study aimed to evaluate the effects of ulinastatin on AKI in patients undergoing off-pump coronary artery bypass (OPCAB) surgery.

METHODS

We hypothesized that the administration of ulinastatin could prevent AKI in OPCAB. Electrical medical records were reviewed to identify OPCAB patients between January 2015 and June 2020. The utilization of ulinastatin was randomly determined and applied during this period. Acute kidney injury was defined according to the KDIGO guideline, and its incidence was compared between the ulinastatin administration group and the control group. To investigate the effect of ulinastatin on renal function, multivariate logistic regression analysis was used to calculate propensity scores for each group.

RESULTS

A total 454 OPCAB were performed, and after following inclusion and exclusion process, 100 patients were identified in the ulinastatin group and 303 patients in the control group. Using 1:2 propensity score matching, we analyzed 100 and 200 patients in the ulinastatin and control groups. The incidence of AKI was similar between the groups (2.5% for the control group, 2.0% for the ulinastatin group, p > 0.999). However, the serum creatinine value on the first post-operative day were significantly lower in the ulinastatin group compared to the control group (0.774 ± 0.179 mg/dL vs 0.823 ± 0.216 mg/dL, P = 0.040), while no significant differences were observed for the other time points (P > 0.05). The length of ICU stay day was significantly shorter in the ulinastatin group (2.91 ± 2.81 day vs 5.22 ± 7.45 day, respectively, P < 0.001).

CONCLUSIONS

Ulinastatin did not have a significant effect on the incidence of AKI; it demonstrated the ability to reduce post-operative serum creatine levels at first post-operative day and shorten the length of ICU stay.

Association between intraoperative hyperglycemia/hyperlactatemia and acute kidney injury following on-pump cardiac surgery: a retrospective cohort study

Background

Despite the long-lasting notion about the substantial contribution of intraoperative un-stabilization of homeostasis factors on the incidence on acute kidney injury (AKI), the possible influence of intraoperative glucose or lactate management, as a modifiable factor, on the development of AKI remains inconclusive.

Objectives

To investigated the relationship between intraoperative hyperglycemia, hyperlactatemia, and postoperative AKI in cardiac surgery.

Methods

A retrospective cohort study was conducted among 4,435 adult patients who underwent on-pump cardiac surgery from July 2019 to March 2022. Intraoperative hyperglycemia and hyperlactatemia were defined as blood glucose levels >10 mmol/L and lactate levels >2 mmol/L, respectively. The primary outcome was the incidence of AKI. All statistical analyses, including t tests, Wilcoxon rank sum tests, chi-square tests, Fisher's exact test, Kolmogorov-Smirnov test, logistic regression models, subgroup analyses, collinearity analysis, and receiver operating characteristic analysis, were performed using the statistical software program R version 4.1.1.

Results

Among the 4,435 patients in the final analysis, a total of 734 (16.55%) patients developed AKI after on-pump cardiac surgery. All studied intraoperative metabolic disorders was associated with increased AKI risk, with most pronounced odds ratio (OR) noted for both hyperglycemia and hyperlactatemia were present intraoperatively [adjusted OR 3.69, 95% confidence intervals (CI) 2.68-5.13, p < 0.001]. Even when hyperglycemia or hyperlactatemia was present alone, the risk of postoperative AKI remained elevated (adjusted OR 1.97, 95% CI 1.50-2.60, p < 0.001).

Conclusion

The presence of intraoperative hyperglycemia and hyperlactatemia may be associated with postoperative acute kidney injury (AKI) in patients undergoing on-pump cardiac surgery. Proper and timely interventions for these metabolic disorders are crucially important in mitigating the risk of AKI.

Machine learning for dynamic and early prediction of acute kidney injury after cardiac surgery

OBJECTIVE

Acute kidney injury after cardiac surgery increases morbidity and mortality. Diagnosis relies on oliguria or increased serum creatinine, which develop 48 to 72 hours after injury. We hypothesized machine learning incorporating preoperative, operative, and intensive care unit data could dynamically predict acute kidney injury before conventional identification.

METHODS

Cardiac surgery patients at a tertiary hospital (2008-2019) were identified using electronic medical records in the Medical Information Mart for Intensive Care IV database. Preoperative and intraoperative parameters included demographics, Charlson Comorbidity subcategories, and operative details. Intensive care unit data included hemodynamics, medications, fluid intake/output, and laboratory results. Kidney Disease: Improving Global Outcomes creatinine criteria were used for acute kidney injury diagnosis. An ensemble machine learning model was trained for hourly predictions of future acute kidney injury within 48 hours. Performance was evaluated by area under the receiver operating characteristic curve and balanced accuracy.

RESULTS

Within the cohort (n = 4267), there were approximately 7 million data points. Median baseline creatinine was 1.0 g/dL (interquartile range, 0.8-1.2), with 17% (735/4267) of patients having chronic kidney disease. Postoperative stage 1 acute kidney injury occurred in 50% (2129/4267), stage 2 occurred in 8% (324/4267), and stage 3 occurred in 4% (183/4267). For hourly prediction of any acute kidney injury over the next 48 hours, area under the receiver operating characteristic curve was 0.82, and balanced accuracy was 75%. For hourly prediction of stage 2 or greater acute kidney injury over the next 48 hours, area under the receiver operating characteristic curve was 0.95 and balanced accuracy was 86%. The model predicted acute kidney injury before clinical detection in 89% of cases.

CONCLUSIONS

Ensemble machine learning models using electronic medical records data can dynamically predict acute kidney injury risk after cardiac surgery. Continuous postoperative risk assessment could facilitate interventions to limit or prevent renal injury.

Usefulness of the N-Terminal of the Prohormone Brain Natriuretic Peptide in Predicting Acute Kidney Injury Requiring Renal Replacement Therapy in Patients Undergoing Heart Valve Surgery

Background and Objectives: By definition, acute kidney injury (AKI) is a clinical syndrome diagnosed when the increase in serum creatinine concentration is >0.3 mg/dL in 48 h or >1.5-fold in the last seven days or when diuresis < 0.5 mL/kg/h for a consecutive 6 h. AKI is one of the severe complications that may occur in the early postoperative period in patients undergoing heart valve surgery, significantly increasing the risk of death. Early implementation of renal replacement therapy increases the chances of improving treatment results in patients with postoperative AKI. The study assessed the predictive ability of selected preoperative and perioperative parameters for the occurrence of postoperative AKI requiring renal replacement therapy in the early postoperative period in a group of patients with severe valvular heart disease. Materials and Methods: A prospective study was conducted on a group of patients undergoing consecutive heart valve surgeries. The primary endpoint was postoperative AKI requiring renal replacement therapy. AKI was diagnosed with an increase in serum creatinine > 0.3 mg/dL in 48 h or >1.5-fold in the previous 7 days and/or a decrease in diuresis < 0.5 mL/kg/h for 6 h. The observation period was until the patient was discharged home or death occurred. Logistic regression analysis was used to assess which variables were predictive of primary endpoint, and odds ratios (OR) were calculated with a 95% confidence interval (CI). Multivariate analysis was based on the result of single factor logistic regression, i.e., to further steps, all statistically significant variables were taken into consideration. Results: A total of 607 patients were included in the study. The primary endpoint occurred in 50 patients. At multivariate analysis: NT-proBNP (OR 1.406; 95% CI 1.015-1.949; p = 0.04), CRP (OR 1.523; 95% CI 1.171-1.980; p = 0.001), EuroSCORE II (OR 1.090; 95% CI 1.014-1.172; p = 0.01), age (OR 1.037; 95% CI 1.001-1.075; p = 0.04) and if they stayed in the intensive care unit longer than 2 days (OR 9.077; 95% CI 2.026-40.663; p = 0.004) remained the independent predictors of the primary endpoint. The mean preoperative NT-proBNP level was 2063 pg/mL (±1751). Thirty-eight patients with AKI requiring renal replacement therapy died in intrahospital follow-up. Conclusions: The results of the presented study indicate that a high preoperative level of NT-proBNP and postoperative hemodynamic instability may be associated with a significant risk of a postoperative AKI requiring renal replacement therapy. The results of the study may also suggest that qualifying for heart valve surgery earlier may be associated with improved prognosis in this group of patients.

Hyperlactatemia in patients undergoing pulmonary endarterectomy with deep hypothermic circulatory arrest: Risk factors and its effects on the outcome

INTRODUCTION

To determine the risk factors of hyperlactatemia in pulmonary endarterectomy (PEA) surgery and assess whether elevated blood lactate levels are associated with adverse outcomes.

METHODS

In this retrospective observational study, a total of 111 consecutive patients who underwent PEA for chronic thromboembolic pulmonary hypertension at the XXX Hospital between December 2016 and January 2022 were included. We retrospectively evaluated arterial blood samples analyzed intraoperatively. The pre- and intraoperative risk factors for hyperlactatemia and the postoperative outcomes were recorded.

RESULTS

Lactate levels gradually increased during surgery. The optimal cut-off lactate level for major postoperative complications, calculated using receiver operating characteristic analysis, was 7.0 mmol/L. Deep hypothermic circulatory arrest (DHCA) duration, nadir hematocrit, and preoperative pulmonary vascular resistance were risk factors for lactate levels >7 mmol/L. Moreover, the intraoperative peak lactate level during PEA under DHCA was found to be a statistically significant predictor of major complications being associated with longer mechanical ventilation time (r = 0.294; p = .003) and intensive care unit length of stay (r = 0.327; p = .001).

CONCLUSIONS

Deep hypothermic circulatory arrest duration, nadir hematocrit, and preoperative pulmonary vascular resistance were associated with hyperlactatemia. Increased lactate levels were independent predictors of longer mechanical ventilation time, intensive care unit length of stay, and major complications.

Prognostic value of ascites in patients with liver cirrhosis undergoing cardiac surgery

INTRODUCTION

Mild or moderate liver cirrhosis increases the risk of complications after cardiac surgery. Ascites is the most common complication associated with liver cirrhosis. However, the prognostic value of ascites on postoperative morbidity and mortality after cardiac surgery remains uninvestigated.

METHODS

A retrospective study included 69 patients with preoperatively diagnosed liver cirrhosis who underwent cardiac surgery between January 2009 and January 2018 at the Department of Cardiothoracic Surgery, University Hospital of Cologne, Germany. The patients were divided into ascites and non-ascites groups based on preoperatively diagnosed ascites. Thirty-day mortality, postoperative complications, length of stay, and blood transfusions were analyzed postoperatively.

RESULTS

Out of the total of 69 patients, 14 (21%) had preoperatively diagnosed ascites. Ascites group had more postoperative complications such as blood transfusions (packed red blood cells: 78.6% vs. 40.0%, p = 0.010; fresh frozen plasma: 57.1% vs. 29.1%, p = 0.049), acute kidney injury (78.6% vs. 45.5%, p = 0.027), longer ICU stay (8 vs. 3 days, p = 0.044) with prolonged mechanical ventilation (57.1% vs. 23.6%, p = 0.015) and tracheotomy (28.6% vs. 3.6%, p = 0.003). The 30-day mortality rate was significantly higher in the ascites group than in the non-ascites group (35.7% vs. 5.5%, p = 0.002).

CONCLUSION

Ascites should be implemented in preoperative risk score assessments in cirrhotic patients undergoing cardiac surgery. Preoperative treatment of ascites could reduce the negative impact of ascites on postoperative complications after cardiac surgery. However, this needs to be thoroughly investigated in prospective randomized clinical trials.

Prevention of cardiac surgery-associated acute kidney injury: a systematic review and meta-analysis of non-pharmacological interventions

BACKGROUND

Cardiac surgery-associated acute kidney injury (CSA-AKI) is frequent. While two network meta-analyses assessed the impact of pharmacological interventions to prevent CSA-AKI, none focused on non-pharmacological interventions. We aim to assess the effectiveness of non-pharmacological interventions to reduce the incidence of CSA-AKI.

METHODS

We searched PubMed, Embase, Central and clinical trial registries from January 1, 2004 (first consensus definition of AKI) to July 1, 2023. Additionally, we conducted manual screening of abstracts of major anesthesia and intensive care conferences over the last 5 years and reference lists of relevant studies. We selected all randomized controlled trials (RCTs) assessing a non-pharmacological intervention to reduce the incidence of CSA-AKI, without language restriction. We excluded RCTs of heart transplantation or involving a pediatric population. The primary outcome variable was CSA-AKI. Two reviewers independently identified trials, extracted data and assessed risk of bias. Random-effects meta-analyses were conducted to calculate risk ratios (RRs) with 95% confidence intervals (CIs). We used the Grading of Recommendations Assessment, Development, and Evaluation to assess the quality of evidence.

RESULTS

We included 86 trials (25,855 patients) evaluating 10 non-pharmacological interventions to reduce the incidence of CSA-AKI. No intervention had high-quality evidence to reduce CSA-AKI. Two interventions were associated with a significant reduction in CSA-AKI incidence, with moderate quality of evidence: goal-directed perfusion (RR, 0.55 [95% CI 0.40-0.76], I2 = 0%; Phet = 0.44) and remote ischemic preconditioning (RR, 0.86 [0.78-0.95]; I2 = 23%; Phet = 0.07). Pulsatile flow during cardiopulmonary bypass was associated with a significant reduction in CSA-AKI incidence but with very low quality of evidence (RR = 0.69 [0.48; 0.99]; I2 = 53%; Phet < 0.01). We found high quality of evidence for lack of effect of restrictive transfusion strategy (RR, 1.02 [95% CI 0.92; 1.12; Phet = 0.67; I2 = 3%) and tight glycemic control (RR, 0.86 [95% CI 0.55; 1.35]; Phet = 0.25; I2 = 26%).

CONCLUSIONS

Two non-pharmacological interventions are likely to reduce CSA-AKI incidence, with moderate quality of evidence: goal-directed perfusion and remote ischemic preconditioning.

Predictive role of arterial lactate in acute kidney injury associated with off-pump coronary artery bypass grafting

Objectives

This observational study aims to explore the predictive role of postoperative arterial lactate in off-pump coronary artery bypass grafting (CABG)-associated acute kidney injury (AKI).

Materials and methods

A total of 500 consecutive patients who underwent off-pump CABG from August 2020 to August 2021 at the Department of Cardiovascular Surgery, Qilu Hospital of Shandong University, were included. Logistic regression analysis was used to confirm the independent risk factors of off-pump CABG-associated AKI. Receiver operating characteristic (ROC) curve was performed to evaluate the discrimination ability and Hosmer–Lemeshow goodness of fit test was performed to evaluate the calibration ability.

Results

The incidence of off-pump CABG-associated AKI was 20.6%. Female gender, preoperative albumin, baseline serum creatinine, 12 h postoperative arterial lactate and duration of mechanical ventilation were independent risk factors. The area under the ROC curve (AUC) of 12 h postoperative arterial lactate for predicting off-pump CABG-associated AKI was 0.756 and the cutoff value was 1.85. The prediction model that incorporated independent risk factors showed reliable predictive ability (AUC = 0.846). Total hospital stay, intensive care unit stay, occurrence of other postoperative complications, and 28-day mortality were all significantly higher in AKI group compared to non-AKI group.

Conclusion

12 h postoperative arterial lactate was a validated predictive biomarker for off-pump CABG-associated AKI. We constructed a predictive model that facilitates the early recognition and management of off-pump CABG-associated AKI.

Valve-in-Valve TAVR versus Redo Surgical Aortic Valve Replacement: Early Outcomes

OBJECTIVE

This study aimed to assess short-term outcomes of patients with failed aortic valve bioprosthesis undergoing valve-in-valve transcatheter aortic valve replacement (ViV-TAVR) or redo surgical aortic valve replacement (rSAVR).

METHODS

Between 2009 and 2019, 90 patients who underwent ViV-TAVR (n = 73) or rSAVR (n = 17) due to failed aortic valve bioprosthesis fulfilled the inclusion criteria. Groups were compared regarding clinical end points, including in-hospital all-cause mortality. Patients with endocarditis and in a need of combined cardiac surgery were excluded from the study.

RESULTS

ViV-TAVR patients were older (78.0 ± 7.4 vs. 62.1 ± 16.2 years, p = 0.012) and showed a higher prevalence of baseline comorbidities such as atrial fibrillation, diabetes mellitus, hyperlipidemia, and arterial hypertension. In-hospital all-cause mortality was higher for rSAVR than in the ViV-TAVR group (17.6 vs. 0%, p < 0.001), whereas intensive care unit stay was more often complicated by blood transfusions for rSAVR patients without differences in cerebrovascular events. The paravalvular leak was detected in 52.1% ViV-TAVR patients compared with 0% among rSAVR patients (p < 0.001).

CONCLUSION

ViV-TAVR can be a safe and feasible alternative treatment option in patients with degenerated aortic valve bioprosthesis. The choice of treatment should include the patient's individual characteristics considering ViV-TAVR as a standard of care.

The importance of liver function assessment before cardiac surgery: A narrative review

The demand for cardiac surgery procedures is increasing globally. Thanks to an improvement in survival driven by medical advances, patients with liver disease undergo cardiac surgery more often. Liver disease is associated with the development of heart failure, especially in patients with advanced cirrhosis. Cardiovascular risk factors can also contribute to the development of both cardiomyopathy and liver disease and heart failure itself can worsen liver function. Despite the risk that liver disease and cirrhosis represent for the perioperative management of patients who undergo cardiac surgery, liver function is often not included in common risk scores for preoperative evaluation. These patients have worse short and long-term survival when compared with other cardiac surgery populations. Preoperative evaluation of liver function, postoperative management and close postoperative follow-up are crucial for avoiding complications and improving results. In the present narrative review, we discuss the pathophysiological components related with postoperative complications and mortality in patients with liver disease who undergo cardiac surgery and provide recommendations for the perioperative management.

Predictive role of the neutrophil: lymphocyte ratio in acute kidney injury associated with off-pump coronary artery bypass grafting

OBJECTIVES

This study aims to investigate whether the ratios of cell types in peripheral blood could be used as reliable predictors of off-pump coronary artery bypass grafting (CABG)-associated acute kidney injury (AKI).

MATERIALS AND METHODS

We retrospectively reviewed patients (n = 420) undergoing off-pump CABG from January 1, 2021 to January 1, 2022 in Qilu Hospital of Shandong University. We used logistic regression analysis to identify the potential predictors of off-pump CABG-associated AKI and construct a predictive model. Receiver operating characteristic (ROC) curve analysis was used to evaluate the predictive ability of predictors and prediction models.

RESULTS

The prevalence of AKI associated with off-pump CABG was 20.95%. Patients in the AKI group had significantly higher ratios of peripheral blood cells on postoperative day (POD)1 than patients in the non-AKI group (P < 0.01). The area under the ROC curve (AUC) of the neutrophil:lymphocyte ratio (NLR) on POD1 for predicting off-pump CABG-associated AKI was 0.780 and the cutoff value was 20.07. Patients with high NLR on POD1 had a poor short-term prognosis. The AUC of the predictive model constructed by logistic regression analysis was 0.882. The sensitivity was 68.2% and the specificity was 93.1%.

CONCLUSION

The NLR on POD1 was a reliable predictive biomarker of off-pump CABG-associated AKI. And we successfully construct a prediction model, which contribute to the early recognition and management of off-pump CABG-associated AKI.

Multicentre evaluation of renal impairment in thoracic surgery (MERITS): a retrospective cohort study

OBJECTIVES

To measure the unit-level variation in Acute Kidney Injury (AKI) incidence post-thoracic surgery over a contemporary 1-year period. Secondary aims include examining the associations with sex, age group, operation type, length of stay and mortality.

DESIGN

A multicentre, observational, retrospective study in thoracic surgery.

SETTING

17 of 35 Society for Cardiothoracic Surgery of Great Britain and Ireland (SCTS) units participated. The student wing, known as SCTS STUDENTS, supported data collection.

PARTICIPANTS

Overall, 15 229 patients were collected of which 15 154 were included for analysis after exclusions. All patients (age≥18 years) undergoing any thoracic surgery from 1 April 2016 to 31 March 2017 were included. For analysis, we excluded patients with preoperative end-stage renal failure and those with incomplete data.

MAIN OUTCOME MEASURES

The primary outcome is the incidence of AKI within 7 days of the procedure or discharge date if earlier. Secondary outcomes include assessing associations with patient demographics (age, sex), type of procedure (open and minimally invasive), length of stay and mortality.

RESULTS

Out of 15 154 patients AKI was diagnosed in 1090 patients (7.2%) within 7 days of surgery with AKI stage 1 (4.8%), stage 2 (1.7%) and stage 3 (0.7%). There was a statistically significant variation in AKI incidence between units from 3.1 to 16.1% (p<0.05). Significant differences between AKI and non-AKI were found in post-operative length of stay (7 vs 3 days, p<0.001), 30-day mortality (9 vs 1.6%, p<0.001), 90-day mortality (14.7 vs 4.4%, p<0.001) and 1-year mortality (23.1 vs 12.2 %, p<0.001).

CONCLUSIONS

Following thoracic surgery, AKI incidence ranged from 3.1% to 16.1% between units (p<0.05) with associations between AKI and both length of stay and mortality. We propose AKI as a suitable comparative and absolute quality measure in thoracic surgery. Reducing rates of AKI may improve patient outcomes, length of stay and reduce costs.

The Effect of Enteral Immunonutrition in the Intensive Care Unit: Does It Impact on Outcomes?

Background: The present research aimed to evaluate the effect on outcomes of immunonutrition (IMN) enteral formulas during the intensive care unit (ICU) stay. Methods: A multicenter prospective observational study was performed. Patient characteristics, disease severity, nutritional status, type of nutritional therapy and outcomes, and laboratory parameters were collected in a database. Statistical differences were analyzed according to the administration of IMN or other types of enteral formulas. Results: In total, 406 patients were included in the analysis, of whom 15.02% (61) received IMN. Univariate analysis showed that patients treated with IMN formulas received higher mean caloric and protein intake, and better 28-day survival (85.2% vs. 73.3%; p = 0.014. Unadjusted Hazard Ratio (HR): 0.15; 95% CI (Confidence Interval): 0.06−0.36; p < 0.001). Once adjusted for confounding factors, multivariate analysis showed a lower need for vasopressor support (OR: 0.49; 95% CI: 0.26−0.91; p = 0.023) and continuous renal replacement therapies (OR: 0.13; 95% CI: 0.01−0.65; p = 0.049) in those patients who received IMN formulas, independently of the severity of the disease. IMN use was also associated with higher protein intake during the administration of nutritional therapy (OR: 6.23; 95% CI: 2.59−15.54; p < 0.001), regardless of the type of patient. No differences were found in the laboratory parameters, except for a trend toward lower triglyceride levels (HR: 0.97; 95% CI: 0.95−0.99; p = 0.045). Conclusion: The use of IMN formulas may be associated with better outcomes (i.e., lower need for vasopressors and continuous renal replacement), together with a trend toward higher protein enteral delivery during the ICU stay. These findings may ultimately be related to their modulating effect on the inflammatory response in the critically ill. NCT Registry: 03634943.

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.

Neutrophil gelatinase-associated lipocalin as a biomarker for predicting acute kidney injury after coronary artery bypass grafting

Background

Early and precocious determination of acute kidney injury (AKI) is essential to prevent morbidity and mortality following coronary artery bypass grafting (CABG). Evaluation of the perioperative renal function is substantial using novel biomarkers other than the late traditional method of using serum creatinine. Plasma neutrophil gelatinase-associated lipocalin (NGAL) is a biomarker investigated for early detection of AKI in patients undergoing coronary artery bypass grafting, and its role has to be determined in this study.

Results

Twenty-five patients undergoing elective CABG were enrolled in this cohort study and were assigned into two groups: group I include the patients that did not develop AKI (no AKI group) and group II include the patients that developed AKI (AKI group). Acute kidney injury based on Kidney Disease: Improving Global Outcomes (KDIGO) classification had been developed in 7 patients (28%). Plasma NGAL levels at 6 h were higher in patients who developed AKI compared with those who did not (302 ± 88.02 vs. 116.50 ± 17.33 ng/m, p value < 0.001). The cut-off value of plasma NGAL levels measured 6 h postoperatively was 145 ng/ml and the area under the receiver-operating characteristic (ROC) curve was 0.965. Results of this study showed that plasma NGAL is a robust early biomarker of AKI, which preceded the rise in serum creatinine by many hours.

Conclusion

This study revealed that earlier diagnosis of acute kidney injury in patients undergoing CABG can be achieved by measuring postoperative plasma NGAL concentration at 6 h.

The relationship between pre-procedural elevated arterial lactate and contrast-induced nephropathy following primary percutaneous coronary intervention

Background

Risk stratification has been one of the main steps in preventing contrast-induced nephropathy (CIN), which is a common complication after percutaneous coronary intervention (PCI). Elevated arterial lactate is a biomarker indicating severe disease condition and post-intervention complications. The relationship between lactate and CIN has not been established. This study is performed to investigate the relationship between elevated arterial lactate level and contrast-induced nephropathy (CIN).

Methods

Patients diagnosed with ST-segment elevated myocardial infarction (STEMI) were prospectively enrolled, with lactate measured within 0.5–1 hours before primary percutaneous coronary intervention (PCI). Patients with cardiopulmonary resuscitation, any forms of severe anaerobic condition, or end-stage renal disease undergoing dialysis were excluded. CIN was defined as an increase in serum creatinine ≥0.5 mg/dL or 25% within 72 hours after PCI. The Mehran Risk Score (MRS) is widely regarded as a classic risk model for CIN and the risk factors of MRS were applied in our multivariate regression analysis.

Results

Of the 227 enrolled patients, 47 (20.7%) developed CIN according to the definition. The mean lactate level was higher in the CIN group than in the non-CIN group (2.68±2.27 vs. 1.74±1.94, P<0.001). The arterial lactate level ≥2.0 mmol/L had 57.5% sensitivity and 75.6% specificity in predicting CIN. The performance of the lactate level in discriminating CIN was similar to that of the MRS (AUC_lac =0.707 vs. AUC_MRS =0.697, P=0.86). After adjusting for other risk factors, lactate ≥2.0 mmol/L still significantly predicted CIN (odds ratio =3.77, 95% CI, 1.77–7.99, P=0.001).

Conclusions

An arterial lactate level of ≥2.0 mmol/L is associated with CIN in STEMI patients after primary PCI.

Diagnosis of Cardiac Surgery-Associated Acute Kidney Injury

Acute kidney injury after cardiac surgery is characterized by specific patterns of damage and recovery that are important to consider for management and outcome. The Kidney Disease: Improving Global Outcomes (KDIGO) classification covers only part of the conceptual framework and is thus insufficient for a comprehensive diagnosis. This review highlights the strengths and limitations of the recent criteria and provides an overview of biomarkers of cardiac surgery-associated acute kidney injury (CSA-AKI). The evolving understanding of CSA-AKI as a time-sensitive condition has increased the demand to enhance the diagnostic criteria and translate biomarkers into clinical practice.

Perioperative hemodynamic optimization in laparoscopic sleeve gastrectomy using stroke volume variation to reduce postoperative nausea and vomiting

BACKGROUND

Risk of postoperative nausea and vomiting (PONV) is usually high among patients undergoing laparoscopic sleeve gastrectomy (LSG). Perioperative hemodynamic optimization using goal-directed fluid therapy (GDFT) based on stroke volume variation (SVV) has been suggested to reduce PONV.

OBJECTIVES

This study aimed to investigate the effectiveness of GDFT on reducing PONV.

SETTING

The operating rooms in China Medical University Hospital.

METHODS

This prospective cohort study included 75 patients undergoing LSG. Patients were randomized into 3 groups: controls (conventional fluid therapy), GDFT-hydroxyethyl starch (GH), and GDFT-lactated Ringer's (GL) groups. In both GDFT groups, optimization of fluid administration was achieved by continuous monitoring and adjusting of SVV. Severity of PONV was evaluated using a standardized questionnaire. Other clinically relevant events, including in-hospital surgical site infections and length of hospital stay were also investigated.

RESULTS

In the GH group, the total volume of fluid administered intraoperatively was significantly lower than that in the GL and control groups (P < .001). Assessment of PONV severity showed a significantly higher score at postoperative 24 hours in the GH group (P < .05), while no significant differences were found between the 3 groups at postoperative 48 hours. No significant differences were observed between the 3 groups in surgical site infections and length of hospital stay.

CONCLUSION

No significant benefit is found in reducing PONV by using GDFT in patients undergoing LSG, although GDFT effectively avoids excessive volume of fluid administration. PONV incidence appears to be higher with intraoperative colloid infusion for GDFT during LSG. Further investigation is warranted to elucidate the mechanism underlying PONV in postoperative LSG.

Associations Between Preoperative Biomarkers and Cardiac Surgery-Associated Acute Kidney Injury in Elderly Patients: A Cohort Study

BACKGROUND

Acute kidney injury (AKI) is associated with mortality after cardiac surgery. Novel risk factors may improve identification of patients at risk for renal injury. The authors evaluated the association between preoperative biomarkers that reflect cardiac, inflammatory, renal, and metabolic disorders and cardiac surgery-associated AKI (CSA-AKI) in elderly patients.

METHODS

This was a secondary analysis of the 2-center prospective cohort study "Anesthesia Geriatric Evaluation." Twelve biomarkers were determined preoperatively in 539 patients. Primary outcome was CSA-AKI. The association between biomarkers and CSA-AKI was investigated with multivariable logistic regression analysis. Secondary outcomes were 1-year mortality and patient-reported disability and were assessed with relative risks (RR) between patients with and without CSA-AKI.

RESULTS

CSA-AKI occurred in 88 (16.3%) patients and was associated with increased risk of mortality (RR, 6.70 [95% confidence interval {CI}, 3.38-13.30]) and disability (RR, 2.13 [95% CI, 1.53-2.95]). Preoperative concentrations of N-terminal pro B-type natriuretic peptide (NT-proBNP), high-sensitive C-reactive protein (hs-CRP), hemoglobin, and magnesium had the strongest association with CSA-AKI. Identification of patients with CSA-AKI improved when a biomarker panel was used (area under the curve [AUC] 0.75 [95% CI, 0.69-0.80]) compared to when only clinical risk factors were used (European System for Cardiac Operative Risk Evaluation [EuroSCORE II] AUC 0.67 [95% CI, 0.62-0.73]).

CONCLUSIONS

Preoperative cardiac, inflammatory, renal, and metabolic biomarkers are associated with CSA-AKI and may improve identification of patients at risk.

Cardiac Surgery-Related Acute Kidney Injury _ Risk Factors, Clinical Course, Management Suggestions

OBJECTIVE

Acute kidney injury (AKI) is a common complication after cardiac surgery (CS). Because a therapeutic regimen remains scarce, the early implementation of preventive strategies is crucial. The authors investigated risk factors and the typical clinical course of CS-associated AKI (CS-AKI) to derive strategies for perioperative clinical routines.

DESIGN

Retrospective data analysis.

SETTING

The data were collected from clinical routines in a maximum care university hospital.

PARTICIPANTS

Patients.

INTERVENTIONS

The authors retrospectively analyzed data from 538 patients who underwent CS.

MEASUREMENTS AND MAIN RESULTS

The median age of the 466 patients included was 66.6 years; 65.7% were men. AKI occurred in 131 (28.1%) patients, mainly (89.0%) starting postoperatively within 72 hours p. Thirty-one (6.7%) patients showed Kidney Disease Improving Global Outcome AKI stage 3. AKI was significantly more frequent in patients with chronic kidney disease (p < 0.001), emergency admission (p < 0.001), heart failure (p < 0.001), and postoperative complications (p < 0.001). In a multivariate analysis, postoperative CS-AKI risk significantly decreased with each 1 or 10 mL/min preoperative glomerular filtration rate (GFR) (odds ratio, 0.962 and 0.677; 95% confidence interval, 0.947-0.977 and 0.577-0.793; p < 0.001 and p < 0.0001). Only in patients who developed Kidney Disease Improving Global Outcome AKI stage 3, an early postoperative trend to decreased GFR and increased creatinine levels was observed.

CONCLUSIONS

Especially in patients with preexisting CKD and signs of CS-AKI occurring on the day of surgery, close monitoring of renal function should be performed for at least 72 hours after CS to detect an onset of AKI early and initiate renal protective strategies. Optimal preoperative fluid management might prevent postoperative AKI.

Risk factors for in-hospital mortality and acute kidney injury in neonatal-pediatric patients receiving extracorporeal membrane oxygenation

BACKGROUND

Acute kidney injury (AKI) is the most frequent complication in critically ill neonatal and pediatric patients receiving extracorporeal membrane oxygenation (ECMO) support. This study analyzed risk factors for in-hospital mortality and the incidence of AKI in neonatal and pediatric patients received ECMO support.

METHODS

We reviewed the medical records of 105 neonatal and 171 pediatric patients who received ECMO support at the intensive care unit (ICU) of a tertiary care university hospital between January 2008 and December 2015. Demographic, clinical, and laboratory data were retrospectively collected as survival and AKI predictors, utilizing the Kidney Disease Improving Global Outcome (KDIGO) consensus definition for AKI.

RESULTS

In the 105 neonatal and 171 pediatric patients, the overall in-hospital mortality rate were 58% and 55% respectively. The incidence of AKI at post-ECMO 24 h were 64.8% and 61.4%. A greater KDIGO_24-h severity was associated with a higher in-hospital mortality rate (chi-square test; p < 0.01) and decreased survival rate (log-rank tests, p < 0.01). In univariate logistic regression analysis of in-hospital mortality, the CVP level at post ECOMO 24-h increased odds ratio (OR) (OR = 1.27 [1.10-1.46], p = 0.001) of in-hospital mortality in neonatal group; as for pediatric group, elevated lactate (OR = 1.12 [1.03-1.20], p = 0.005) and PT (OR = 1.86 [1.17-2.96], p = 0.009) increased OR of in-hospital mortality. And the KDIGO_24h stage 3 had the strongest association with in-hospital mortality in both neonatal (p = 0.005) and pediatric (p = 0.001) groups. In multivariate OR of neonatal and pediatric groups were 4.38 [1.46-13.16] (p = 0.009) and 3.76 [1.70-8.33] (p = 0.001), respectively.

CONCLUSIONS

AKI was a significant risk factor for in-hospital mortality in the neonatal and pediatric patients who received ECMO support. A greater KDIGO24-h severity was associated with higher mortality rates and decreased survival rate in both neonatal and pediatric groups. Of note, KDIGO24h can be an easy and early tool for the prognosis of AKI in the neonatal and pediatric patients.

Prediction Scores for Any-Stage and Stage-3 Acute Kidney Injury After Adult Cardiac Surgery in a Chinese Population

OBJECTIVES

This study was performed to internally derive and then validate risk score systems using preoperative and intraoperative variables to predict the occurrence of any-stage (stage 1, 2, 3) and stage-3 acute kidney injury (AKI) within seven days of cardiac surgery.

DESIGN

Single-center, retrospective, observational study.

SETTING

Single, large, tertiary care center.

PARTICIPANTS

Adult patients undergoing open cardiac surgery between January 1, 2012, and January 1, 2019.

MEASUREMENTS AND MAIN RESULTS

The clinical data were divided into the following two groups: a derivation cohort (n = 43,799) and a validation cohort (n = 14,600). AKI was defined using the Kidney Disease: Improving Global Outcomes criteria. Multivariate logistic regression analysis was used to develop the prediction models. The overall prevalence of any-stage AKI and stage-3 AKI after cardiac surgery were 34.3% and 1.7%, respectively. The discriminatory ability of the any-stage AKI prediction model measured with the area under the curve (AUC) was acceptable (AUC = 0.69, 95% confidence interval 0.68-0.69), and the calibration measured with the Hosmer-Lemeshow test was good (p = 0.95). The AUC for the stage-3 AKI prediction model was 0.84 (95% confidence interval 0.83-0.85), and the Hosmer-Lemeshow test also indicated a good calibration (p = 0.73).

CONCLUSIONS

This research study, which used preoperative and intraoperative variables, derived and internally validated two predictive scoring systems for any-stage AKI and stage-3 AKI as defined by modified Kidney Disease: Improving Global Outcomes criteria using a very large cohort of Chinese cardiac surgical patients.

Impact of urgent coronary artery bypass grafting on acute kidney injury : A matched cohort study

OBJECTIVES

There is limited knowledge regarding the specific interrelationships between urgent coronary artery bypass graft (U-CABG) surgery and postoperative acute kidney injury (AKI). We aimed to (1) analyze the impact of urgent CABG (U-CABG) on the incidence and severity of postoperative AKI, (2) estimate the influence of AKI after U‑CABG or elective CABG (E-CABG) on mortality and (3) identify risk factors for AKI depending on the urgency of operation.

RESULTS

U‑CABG patients showed a higher incidence of AKI (49.8% vs. E‑CABG: 39.7%; p = 0.026), especially for higher AKI stages 2 + 3. In-hospital mortality was higher in U‑CABG patients (12.6%) compared to E‑CABG patients (2.3%; p < 0.001). The impact of AKI on mortality did not differ, but showed a strong coherency between higher AKI stages (2 + 3) and mortality (stage 1: OR 2.409, 95% CI 1.017-5.706; p = 0.046 vs. stage 2 + 3: OR 5.577; 95% CI 2.033-15.3; p = 0.001). Univariate logistic regression analysis revealed that preoperative renal impairment, peripheral vascular disease and transfusion of more than two red blood cell concentrates were predictors for postoperative AKI in both groups.

CONCLUSIONS

U‑CABG is a risk factor for postoperative AKI and even "mild" AKI leads to a significantly higher mortality. Hence, the prevention of modifiable risk factors might reduce the incidence of postoperative AKI and thus improve outcome.

The Incidence and Risk Factors for Persistent Acute Kidney Injury Following Total Cavopulmonary Connection Surgery: A Single-Center Retrospective Analysis of 465 Children

Background: Acute kidney injury (AKI) after cardiac surgery contributes to adverse outcomes. We aimed to assess the incidence and identify the predictors for persistent AKI after total cavopulmonary connection (TCPC) surgery. Methods: A retrospective study, including 465 children undergoing TCPC surgery from 2010 to 2019, was conducted. We used pRIFLE criteria to define AKI and defined persistent AKI as AKIs occurring between post-operative day1 (POD1) and POD3 and sustaining at least on POD7. Univariate and multivariate logistic regressions were applied to analyze the predictors for persistent AKI. Results: A total of 35.3% patients developed AKI between POD1 to POD3 and 15.5% patents had persistent AKI after TCPC. Patients with persistent AKI had prolonged mechanical ventilation and ICU stay, and had higher rates of renal replacement treatment and reintubation, which was associated with higher hospitalization costs and in-hospital mortality. The independent predictors for persistent AKI were peripheral oxygen saturation (SpO2) upon admission, intraoperative fluid balance, POD0 maximal lactic acid, renal perfusion pressure (RPP), POD0 estimated glomerular filtration rate and POD0 total bilirubin. The areas under receiver operating characteristic curve (AUC) in the total cohort and the subgroup undergoing TCPC surgery after 2017 were 0.75 (95% CI, 0.66-0.82) and 0.87 (95% CI, 0.77-0.97), respectively. The acceptable AUCs (nearly 0.7) were achieved in other 5 subgroups and good calibration ability (p ≥ 0.05) were achieved in the total cohort and all six subgroups. Conclusions: Persistent AKI after TCPC was common and strongly associated with poorer in-hospital outcomes in Chinese pediatric patients. Six perioperative variables, including SpO2, intraoperative fluid balance, POD0 maximal lactic acid, RPP, POD0 moderate-to-severe kidney injury and POD0 total bilirubin, were identified as independent predictors for persistent AKI. Our findings may help to perform an early risk stratification for these vulnerable patients and improve their outcomes.

Effects of cardiopulmonary bypass perfusion temperature on perioperative renal function in adult patients undergoing cardiac surgery

Aims and objective

The primary objective of this investigation was to study the effects of cardiopulmonary bypass (CPB) perfusion temperature on renal function parameters [serum creatinine, creatinine clearance, urine albumin, urine protein, and urine albumin/creatinine ratio (ACR)]. The secondary objective was to detect renal complications of CPB.

Materials and methods

This is a prospective longitudinal study of 30 adult patients (17 men, 13 women; mean age, 53.37 ± 16.02 years) who underwent valvular heart surgery [with or without coronary artery bypass grafting (CABG)]. Serum creatinine, creatinine clearance, urine protein, urine albumin, and urine ACR were collected during CPB (at 28 °C, 32 °C, and 37 °C) and postoperatively (at 12 hours, 24 hours, and 48 hours). Data were analyzed using one-way repeated-measures analysis of variance (ANOVA). A significant ANOVA was followed by a Bonferroni–Holm post hoc test.

Results

Although serum creatinine (p < 0.001) and creatinine clearance (p = 0.0016) underwent a significant ANOVA change (p < 0.001 and p = 0.0016, respectively) after CPB, there was no statistically significant change compared with their baseline values. Urine ACR showed a significant change at 28 °C (p < 0.01), 32 °C (p < 0.01), and 37 °C (p < 0.05) as compared with baseline values. No significant change in urine albumin was observed during CPB or up to 24 hours. A significant change occurred after 48 hours of CPB (p < 0.05). A significant increase in urine protein was noted after CPB at 12 hours (p < 0.01), 24 hours (p < 0.01), and 48 hours (p < 0.01). Overall, 12 (40%) patients had acute kidney injury (AKI). Ten (33.33%) patients had stage I AKI, one patient progressed to AKI stage II, and another to AKI stage III. Of the 10 patients who had stage I AKI, eight had complete recovery within 48 hours.

Conclusions

CPB with moderate hypothermia for valvular heart surgeries can be performed safely in patients with adequate renal functional reserve. The glomerular permeability across the Bowman’s capsule increases after CPB as evidenced by significant proteinuria at 12 hours and increased albuminuria at 48 hours after surgery. There is an increased risk of transient stage I AKI after CPB, from which patients recover within 48 hours.

Reassessment of kidney function equations in predicting long-term survival in cardiac surgery

BACKGROUND/OBJECTIVES

Chronic kidney disease (CKD) is a risk factor for long-term survival in cardiac surgery. The Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD) study, CKD Epidemiology Collaboration (CKD-EPI), revised Lund-Malmö (LM), and full age spectrum equations are used to estimate glomerular filtration rates (eGFR), but each have advantages and disadvantages. Our objective was to determine which equation better predicts long-term survival.

METHODS

Data on 1492 consecutive patients who underwent isolated off-pump coronary artery bypass surgery between September 1996 and December 2008 were prospectively collected. Preoperative and postoperative eGFR were calculated using the five equations and compared using Cox regression analyses and time-dependent receiver operating characteristic (ROC) curves at 10 years.

RESULTS

In a Cox regression model after correction for significant predictors of long-term mortality, adjusted hazard ratios (HR) for one standard deviation increase in preoperative eGFR were 0.661 (P < .0001), 0.844 (P = .0166), 0.787 (P = .0002), 0.746 (P < .0001), and 0.717 (P < .0001) for the CG, MDRD, CKD-EPI, LM, and FAS equations, respectively. The areas under the time-dependent ROC curve at 10 years also showed that the CG formula has a better predictive value. Postoperative eGFR at discharge were also significant predictors of long-term mortality (HR = 0.603, P < .0001; HR = 0.725, P < .0001; HR = 0.688, P < .0001; HR = 0.673, P < .0001; HR = 0.632, P < .0001 for the CG, MDRD, CKD-EPI, LM, and FAS equations, respectively).

CONCLUSIONS

The CG formula was shown to better predict survival in cardiac surgery, though the FAS equation has a comparable prognostic value. Additionally, postoperative eGFR at discharge also predicted long-term survival.

Management of Acute Kidney Injury Following Major Abdominal Surgery: A Contemporary Review

Acute kidney injury (AKI) is a frequent occurrence following major abdominal surgery and is independently associated with both in-hospital and long-term mortality, as well as with a higher risk of progressing to chronic kidney disease (CKD) and cardiovascular events. Postoperative AKI can account for up to 40% of in-hospital AKI cases. Given the differences in patient characteristics and the pathophysiology of postoperative AKI, it is inappropriate to assume that the management after noncardiac and nonvascular surgery are the same as those after cardiac and vascular surgery. This article provides a comprehensive review on the available evidence on the management of postoperative AKI in the setting of major abdominal surgery.

The impact of severe acute kidney injury requiring renal replacement therapy on survival and renal function of heart transplant recipients - a UK cohort study

Severe acute kidney injury (AKI), defined as requiring renal replacement therapy (RRT), is associated with higher mortality postheart transplantation, but its long-term renal consequences are not known. Anonymized data of 3365 patients, who underwent heart transplantation between 1995 and 2017, were retrieved from the UK Transplant Registry. Multivariable binary logistic regression was performed to identify risk factors for severe AKI requiring RRT, Kaplan-Meier analysis to compare survival and renal function deterioration of the RRT and non-RRT groups, and multivariable Cox regression model to identify predicting factors of mortality and end-stage renal disease (ESRD). 26.0% of heart recipients received RRT post-transplant. The RRT group has lower survival rates at all time points, especially in the immediate post-transplant period. However, conditional on 3 months survival, older age, diabetes and coronary heart disease, but not post-transplant RRT, were the risk factors for long-term survival. The predicting factors for ESRD were insulin-dependent diabetes, renal function at transplantation, eGFR decline in the first 3 months post-transplant, post-transplant severe AKI and transplantation era. Severe AKI requiring RRT post-transplant is associated with worse short-term survival, but has no impact on long-term mortality. It also accelerates recipients' renal function deterioration in the long term.

Using a quality improvement initiative to reduce acute kidney injury during on-pump coronary artery bypass grafting

INTRODUCTION

In response to a perceived high incidence of acute kidney injury following cardiopulmonary bypass at our institution, a quality improvement initiative consisting of a systematic change to a delivered oxygen (DO₂) goal-directed perfusion practice was implemented. We sought to maintain DO₂ > 270 mL/min/m² to reduce the incidence of acute kidney injury.

METHODS

'The study population included all patients receiving isolated, non-emergent, on-pump coronary artery bypass grafting from January 2015 through December 2018, excluding patients requiring preoperative hemodialysis. DO₂ goal-directed perfusion was instituted in February 2017. Acute kidney injury was defined using Acute Kidney Injury Network criteria.

RESULTS

The pre-goal-directed perfusion cohort included 257 patients, and the post-goal-directed perfusion cohort included 226 patients. The DO₂ was significantly higher in the post-goal-directed perfusion group (p < 0.001). Postoperative change in serum creatinine and incidence of acute kidney injury were significantly lower in the post-goal-directed perfusion group (p < 0.001, p = 0.001, respectively). Estimation with probit and ordered probit models support these findings.

CONCLUSION

This initiative confirms previous assertions that DO₂ is a critical intraoperative parameter and should direct perfusion intervention accordingly.

Endothelial-Dependent Vasomotor Dysfunction in Infants After Cardiopulmonary Bypass

OBJECTIVES

Cardiopulmonary bypass-induced endothelial dysfunction has been inferred by changes in pulmonary vascular resistance, alterations in circulating biomarkers, and postoperative capillary leak. Endothelial-dependent vasomotor dysfunction of the systemic vasculature has never been quantified in this setting. The objective of the present study was to quantify acute effects of cardiopulmonary bypass on endothelial vasomotor control and attempt to correlate these effects with postoperative cytokines, tissue edema, and clinical outcomes in infants.

DESIGN

Single-center prospective observational cohort pilot study.

SETTING

Pediatric cardiac ICU at a tertiary children's hospital.

PATIENTS

Children less than 1 year old requiring cardiopulmonary bypass for repair of a congenital heart lesion.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Laser Doppler perfusion monitoring was coupled with local iontophoresis of acetylcholine (endothelium-dependent vasodilator) or sodium nitroprusside (endothelium-independent vasodilator) to quantify endothelial-dependent vasomotor function in the cutaneous microcirculation. Measurements were obtained preoperatively, 2-4 hours, and 24 hours after separation from cardiopulmonary bypass. Fifteen patients completed all laser Doppler perfusion monitor (Perimed, Järfälla, Sweden) measurements. Comparing prebypass with 2-4 hours postbypass responses, there was a decrease in both peak perfusion (p = 0.0006) and area under the dose-response curve (p = 0.005) following acetylcholine, but no change in responses to sodium nitroprusside. Twenty-four hours after bypass responsiveness to acetylcholine improved, but typically remained depressed from baseline. Conserved endothelial function was associated with higher urine output during the first 48 postoperative hours (R = 0.43; p = 0.008).

CONCLUSIONS

Cutaneous endothelial dysfunction is present in infants immediately following cardiopulmonary bypass and recovers significantly in some patients within 24 hours postoperatively. Confirmation of an association between persistent endothelial-dependent vasomotor dysfunction and decreased urine output could have important clinical implications. Ongoing research will explore the pattern of endothelial-dependent vasomotor dysfunction after cardiopulmonary bypass and its relationship with biochemical markers of inflammation and clinical outcomes.

Association between preoperative aspirin and acute kidney injury following coronary artery bypass grafting

OBJECTIVE

To test the hypothesis that preoperative aspirin administered within 24 hours before coronary artery bypass grafting (CABG) could reduce the incidence of postoperative acute kidney injury (AKI) following CABG.

METHODS

In this retrospective study, 696 patients were assigned to groups according to the time interval between their last aspirin dose administration and the time of surgery. A total of 322 patients received aspirin ≤24 hours before CABG, and 374 patients received aspirin between 24 and 48 hours before CABG. The primary outcome was postoperative AKI of any stage as defined by the Kidney Disease Improving Global Outcomes criteria. Propensity score matching selected 274 pairs for the final comparison.

RESULTS

Multivariable analysis showed that administration of aspirin within 24 hours of CABG was independently associated with reduction of AKI incidence by 36% (odds ratio, 0.64; 95% confidence interval, 0.45-0.91; P = .014). It was also noted that patients receiving their last aspirin dose ≤24 hours before CABG had a significantly higher glomerular filtration rate at discharge compared with patients who received aspirin between 24 and 48 hours before CABG. Propensity score matching analysis showed that patients receiving aspirin within 24 hours before CABG had a lower incidence of AKI compared with patients who discontinued aspirin between 24 and 48 hours before CABG (25.1% vs 36.8%; P = .004).

CONCLUSIONS

Continuation of aspirin until the day of surgery, with the last aspirin dose administered ≤24 hours before CABG, is associated with a significant reduction of postoperative AKI.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Anisocytosis predicts postoperative renal replacement therapy in patients undergoing heart valve surgery

BACKGROUND

Acute kidney injury (AKI) is one of the serious postoperative complications in patients undergoing heart valve surgery. The aim of the present study was to identify selected biomarkers to predict AKI requiring renal replacement.

METHODS

A prospective study was conducted on a group of 751 patients undergoing heart valve surgery. The data on risk factors, preoperative complete blood count, course of operations and postoperative period was assessed. The primary endpoint at the 30-day follow-up was postoperative AKI requiring renal replacement therapy. The secondary end-point was death from all causes in patients with postoperative AKI requiring renal replacement.

RESULTS

The primary endpoint occurred in 46 patients. At multivariate analysis: age, red cell distribution width (RDW) and C-reactive protein remained independent predictors of the primary endpoint. Hemoglobin and RDW were associated with an increased risk of death.

CONCLUSIONS

Elevated RDW is associated with a higher risk of postoperative AKI and death in patients with AKI.

Usefulness of High Estimated Pulmonary Artery Systolic Pressure to Predict Acute Kidney Injury After Cardiac Valve Operations

High estimated pulmonary artery systolic pressure (ePASP) has been established as a detrimental predictor for adverse outcomes in patients with chronic kidney disease. However, the relation between preoperative high ePASP and the development of cardiac surgery associated acute kidney injury (CSA-AKI) has not been validated. We performed a retrospective cohort study of adult patients who underwent valve surgery in 2015 at Zhongshan Hospital, Fudan University. Right ventricular systolic pressure, a surrogate for pulmonary systolic pressure, was estimated in the study group of 1056 patients by preoperative echocardiography. CSA-AKI was defined based on the Kidney Disease Improving Global Outcomes criteria. The relation between preoperative ePASP and CSA-AKI was demonstrated with the use of multivariate analysis after adjusting for potential risk factors for CSA-AKI. Of these patients, preoperative ePASP was 44.5 ± 14.9 mm Hg. 401 (38%) patients developed CSA-AKI in which 73 patients (6.9%) suffered from severe AKI (stage II and III). Multivariate analysis showed that preoperative ePASP was independently associated with CSA-AKI (odds ratio per 10 mm Hg increment, 1.099; 95% confidence interval, 1.003 to 1.204; p = 0.042). Preoperative ePASP more than 60 mm Hg was found to be linked with the increasing incidence of AKI by 62% and in-hospital mortality by over 300%, but not linked with severe AKI or renal replacement therapy. In conclusion, an increase in preoperative ePASP was independently and significantly associated with the development of CSA-AKI in patients who underwent valve surgery. Such relation between preoperative ePASP and CSA-AKI could provide a novel therapeutic target against prevention of AKI.

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study

BACKGROUND

Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery.

METHODS

This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation.

RESULTS

A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65).

DISCUSSION

Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability.

Long-term risk of adverse outcomes after acute kidney injury: a systematic review and meta-analysis of cohort studies using consensus definitions of exposure

Reliable estimates of the long-term outcomes of acute kidney injury (AKI) are needed to inform clinical practice and guide allocation of health care resources. This systematic review and meta-analysis aimed to quantify the association between AKI and chronic kidney disease (CKD), end-stage kidney disease (ESKD), and death. Systematic searches were performed through EMBASE, MEDLINE, and grey literature sources to identify cohort studies in hospitalized adults that used standardized definitions for AKI, included a non-exposed comparator, and followed patients for at least 1 year. Risk of bias was assessed by the Newcastle-Ottawa Scale. Random effects meta-analyses were performed to pool risk estimates; subgroup, sensitivity, and meta-regression analyses were used to investigate heterogeneity. Of 4973 citations, 82 studies (comprising 2,017,437 participants) were eligible for inclusion. Common sources of bias included incomplete reporting of outcome data, missing biochemical values, and inadequate adjustment for confounders. Individuals with AKI were at increased risk of new or progressive CKD (HR 2.67, 95% CI 1.99-3.58; 17.76 versus 7.59 cases per 100 person-years), ESKD (HR 4.81, 95% CI 3.04-7.62; 0.47 versus 0.08 cases per 100 person-years), and death (HR 1.80, 95% CI 1.61-2.02; 13.19 versus 7.26 deaths per 100 person-years). A gradient of risk across increasing AKI stages was demonstrated for all outcomes. For mortality, the magnitude of risk was also modified by clinical setting, baseline kidney function, diabetes, and coronary heart disease. These findings establish the poor long-term outcomes of AKI while highlighting the importance of injury severity and clinical setting in the estimation of risk.

Preoperative risk assessment improves biomarker detection for predicting acute kidney injury after cardiac surgery

Background

Although urinary neutrophil gelatinase-associated lipocalin (NGAL) has emerged as a promising biomarker for the early detection of kidney injury, previous studies of adult patients who underwent cardiac surgery have reported only moderate discrimination. The age, creatinine, and ejection fraction (ACEF) score is a preoperative validated risk model with satisfactory accuracy for predicting AKI following cardiac surgery. It remains unknown whether combining preoperative risk assessment through ACEF scores followed by urinary NGAL test in a population of high-risk individuals is an optimal approach with improved predictive performance.

Material and methods

A total of 177 consecutive patients who underwent cardiac surgery were enrolled. Clinical characteristics, prognostic model scores, and outcomes were assessed. Urinary NGAL were examined within 6 hours after cardiac surgery. Patients were stratified according to preoperative ACEF scores, and comparisons were made using the area under the receiver operator characteristic curve (AUROC) for the prediction of AKI.

Results

A total of 45.8% (81/177) of the patients had AKI. As expected, patients with ACEF scores ≥ 1.1 were older and more likely to have class III or IV heart failure. They were also more likely to have diabetes mellitus, myocardial infarction, and peripheral arterial disease. Urinary NGAL alone moderately predicted AKI, with an AUROC of 0.732. Risk stratification by ACEF scores ≥ 1.1 substantially improved the AUROC of urinary NGAL to 0.873 (95% confidence interval, 0.784–0.961; P < .001).

Conclusions

Risk stratification by preoperative ACEF scores ≥ 1.1, followed by postoperative urinary NGAL, provides more satisfactory risk discrimination than does urinary NGAL alone for the early detection of AKI after cardiac surgery. Future studies should investigate whether this strategy could improve the outcomes and cost-effectiveness of care in patients undergoing cardiac surgery.

Risk of Preeclampsia and Pregnancy Complications in Women With a History of Acute Kidney Injury

An episode of clinically recovered acute kidney injury (r-AKI) has been identified as a risk factor for future hypertension and cardiovascular disease. Our objective was to assess whether r-AKI was associated with future preeclampsia and other adverse pregnancy outcomes and to identify whether severity of AKI or time interval between AKI and pregnancy was associated with pregnancy complications. We conducted a retrospective cohort study of women who delivered infants between 1998 and 2016 at Massachusetts General Hospital. AKI was defined using the 2012 Kidney Disease Improving Global Outcomes laboratory criteria with subsequent clinical recovery (estimate glomerular filtration rate, >90 mL/min per 1.73 m² before conception). AKI was further classified by severity (Kidney Disease Improving Global Outcomes stages 1-3) and time interval between AKI episode and the start of pregnancy. Women with r-AKI had an increased rate of preeclampsia compared with women without previous r-AKI (22% versus 9%; P<0.001). Infants of women with r-AKI were born earlier (gestational age, 38.2±3.0 versus 39.0±2.2 weeks; P<0.001) and were more likely to be small for gestational age (9% versus 5%; P=0.002). Increasing severity of r-AKI was associated with increased risk of preeclampsia for stages 2 and 3 AKI (adjusted odds ratio, 3.5; 95% confidence interval, 2.1-5.7 and adjusted odds ratio, 6.5; 95% confidence interval, 3.5-12.0, respectively), but not for stage 1 (adjusted odds ratio, 1.7; 95% confidence interval, 0.9-3.2). A history of AKI before pregnancy, despite apparent full recovery, was associated with increased risk of pregnancy complications. Severity and timing of the AKI episode modified the risk.

Applicability of the Cleveland clinic scoring system for the risk prediction of acute kidney injury after cardiac surgery in a South Asian cohort

Background

Acute kidney injury (AKI) after cardiac surgery is a frequent post-operative complication associated with an increased risk of mortality, morbidity and hospital costs. Preoperative risk scores such as the Cleveland Clinic Scoring Tool (CCST) have been validated in Western population group to identify patients at higher risk of AKI and may facilitate preventive strategies. However, the scoring tool has not been validated systematically in a South Asian cohort. We aimed to evaluate the applicability of the CCST in prediction of AKI after open cardiac surgery in a South–Indian tertiary care center.

Materials and methods

A retrospective study of all patients who underwent elective open cardiac surgery over a 4 year period from Jan 2012 to Dec 2015 at a single centre were included and relevant details extracted from a comprehensive chart review. The primary outcome was AKI as defined by the Kidney Disease Improving Global Outcomes (KDIGO) criteria. Patients were risk stratified as per the CCST to assess for prediction of AKI into low risk (0–2), intermediate risk (3–5) and high risk (>6) groups.

Results

A total of 276 patients underwent open cardiac surgery with mean age of 51.5 ± 13.06 yrs. This included 177 (64.1%) males and 99 females (35.8%). Overall incidence of AKI was 6.88%. Mean age, gender, BMI, preoperative serum creatinine, diabetes mellitus, chronic obstructive pulmonary disease, cardiopulmonary bypass time was similar in patients who developed AKI vs those who did not have AKI postoperatively. The mean CCST scores were 1.6 in those without AKI, 1.5 in stage 1, 3.0 in stage 2 and 3.4 in stage 3 AKI. Higher risk scores predicted greater risk of AKI. A total of 106 patients (38.4%) were on ACE/ARB, 119 patients (43.1%) received beta-blockers, 110 (39.8%) received diuretics while 144(52.1%) had received preoperative statins. Comparison of drug use between the two groups revealed that preoperative use of ACEI/ARB was associated with highest risk of AKI (p = 0.006). Mortality rate was also high at 15.7% in those with AKI compared to 3.1% in non-AKI group (p = 0.04).

Conclusion

The modified CCST was valid in risk identification of patients with severe stage of AKI but did not have strong discrimination for early AKI stages. Preoperative statin use did not protect against AKI in our study, however preoperative ARB/ACEI use was significantly associated with occurrence of postoperative AKI.