Cardiac surgery-associated acute kidney injury

Biomarkers of acute kidney injury: From discovery to the future of clinical practice

Purpose of this review Acute kidney injury (AKI) is a complex syndrome whose development is associated with an increased morbidity and mortality. Recent studies show that this syndrome is a common complication in critically ill and surgical patients the trajectory of which may differ. As AKI can be induced by different triggers, it is complex and therefore challenging to manage patients with AKI. This review strives to provide a brief historical perspective on AKI, elucidate recent developments in diagnosing and managing AKI, and show the current usage of novel biomarkers in both clinical routine and research. In addition, we provide a perspective on potential future developments and their impact of AKI understanding and management. Recent findings/developments Recent studies show the merits of stress and damage biomarkers, highlighting limitations of the current KDIGO definition that only uses the functional biomarkers serum creatinine and urine output. The use of novel biomarkers led to the introduction of the concept of "subclinical AKI". This new classification may allow a more distinct management of affected or at risk patients. Ongoing studies, such as BigpAK-2 and PrevProgAKI, investigate the implementation of biomarker-guided interventions in clinical practice and may demonstrate an improvement in patients' outcome. Summary The ongoing scientific efforts surrounding AKI have deepened our understanding of the syndrome prompting an expansion of existing concepts. A future integration of stress and damage biomarkers in AKI management, may lead to an individualized therapy in this area.

Intraoperative Glucose and Kidney Injury After On-Pump Cardiac Surgery: A Retrospective Cohort Study

INTRODUCTION

Acute kidney injury (AKI) is a common complication after on-pump cardiac surgery, and previous studies have suggested that blood glucose is associated with postoperative AKI. However, limited evidence is available regarding intraoperative glycemic thresholds in cardiac surgery. The aim of this study was to explore the association between peak intraoperative blood glucose and postoperative AKI, and determine the cut-off values for intraoperative glucose concentration associated with an increased risk of AKI.

METHODS

The study was retrospective and single-centered. Adult patients in West China Hospital of Sichuan University who underwent on-pump cardiac surgery (n = 3375) were included. The primary outcome was the incidence of AKI. Multivariable logistic analysis using restricted cubic spline was performed to explore the association between intraoperative blood glucose and postoperative AKI.

RESULTS

The incidence of AKI in the study population was 18.0% (607 of 3375). Patients who developed AKI had a significantly higher peak intraoperative glucose during the surgery compared to those without AKI. After adjustment for confounders, the incidence of AKI increased with peak intraoperative blood glucose (adjusted odds ratio, 1.08, 95% confidence interval 1.03, 1.12). Furthermore, it was demonstrated that the possibility of AKI was relatively flat till 127.8 mg/dL (7.1 mmol/L) glucose levels which started to rapidly increase afterward.

CONCLUSIONS

Increased intraoperative blood glucose was associated with an increased risk of AKI. Among patients undergoing on-pump cardiac surgery, avoiding a high glucose peak (i.e., below 127.8 mg/dL [7.1 mmol/L]) may reduce the risk of postoperative AKI.

TAG-FREE GLYCOSYLATED RHMFG-E8 AS A THERAPY FOR ACUTE KIDNEY INJURY

ABSTRACT

Background: Acute kidney injury (AKI) can result from renal ischemia and reperfusion (I/R) and often occurs during surgical procedures in cardiac, liver, kidney transplantation, and trauma-hemorrhage. Milk fat globule epidermal growth factor-factor VIII (MFG-E8) functions as a bridging molecule to promote the removal of dying cells by professional phagocytes. Because MFG-E8 promotes clearance of apoptotic cells, we have explored its therapeutic potential in various organ injury conditions. To develop human MFG-E8 as a potential therapy, we have generated a human cell-expressed, and thus glycosylated, tag-free recombinant human (rh) MFG-E8 and tested its safety and biological activity in vitro . We hypothesize that the tag-free glycosylated rhMFG-E8 is protective in I/R-induced AKI and it can be developed as an effective therapy for AKI. Methods: To assess the pharmacokinetic properties of the tag-free rhMFG-E8, Sprague-Dawley rats were either untreated or treated with a bolus dose of the tag-free rhMFG-E8, blood collected at various time points and the recovery of human MFG-E8 in the blood were measured by ELISA. Adult male C57BL6 mice underwent bilateral renal ischemia for 30 min, and immediately upon reperfusion, mice were treated intraperitoneally with either normal saline (vehicle) or 20 μg/kg human cell expressed, glycosylated tag-free rhMFG-E8. At either 24 h or 48 h after I/R, blood and kidneys were harvested for further analysis. In separate cohorts of mice after I/R and treatment, mice were observed for 10 days, and survival recorded. Results: AKI rats treated with the tag-free rhMFG-E8 had similar half-life as those in the treated control rats. At 48 h after I/R-induced AKI, renal function markers, blood urea nitrogen, and creatinine were increased and treatment with the tag-free rhMFG-E8 significantly decreased these markers. At both 24 h and 48 h after AKI, inflammatory cytokines, TNF-α, IL-6, and IL-1β were increased and treatment decreased these levels. The kidney mRNA expressions of these cytokines were also increased at 24 h after AKI and treatment significantly decreased those mRNA expressions. Histologically, at 48 h after AKI, tubular damage, and the number of TUNEL staining cells were increased and treatment markedly decreased these measurements. Administration of tag-free rhMFG-E8 at the time of reperfusion improved survival in a 10-day survival study. Conclusion: Our new human cell-expressed tag-free rhMFG-E8 is protective in I/R-induced AKI and it may have the potential to be further developed as a safe and effective therapy for AKI.

Incidence, Risk Factors and Outcomes of Acute Kidney Injury in Neonates Undergoing Open-heart Surgeries: Single Center Experience

Background

Incidence and outcomes of acute kidney injury (AKI) among neonates who underwent open-heart surgery are not well highlighted in the literature. We aim to assess the incidence, risk factors, and outcome of AKI among neonates undergoing open-heart surgery.

Methods

This is a retrospective cohort study between 2016 and 2021 for all neonates requiring open heart surgery. The cases were divided into 2 groups: the AKI (index) group and the non-AKI (control) group. The two groups were statistically compared for risk factors, needs for dialysis, and outcomes.

Results

100 patients fulfilled the inclusion criteria. Among them, 74 (74%) developed AKI, including 41 (55%), 15 (21%), and 18 (24%) patients in KDIGO stages 1, 2, and 3, respectively. Multivariate analysis comparing both groups demonstrated that low pre-operative creatinine (p = 0.01), prolonged bypass time (p = 0.0004) and high vasoactive inotropic score (VIS), (p = 0.0008) were risk factors for developing AKI post-operatively. Furthermore, in the AKI group, 17 (23%) neonates required renal replacement therapy in the form of peritoneal dialysis. The length of stay was higher in the AKI index group (p = 0.015). Patients who had AKI recovered their kidney function at discharge. There was no difference in mortality between both groups.

Conclusion

The AKI occurred in 74% of neonates undergoing open-heart surgery, with 23% of them needing peritoneal dialysis. Low pre-operative creatinine, high VIS score, and prolonged bypass time are potential risk factors for AKI development after neonatal open-heart surgery. AKI may lead to prolonged hospitalization, though most affected patients recovered their normal kidney function at discharge.

Effect of vitamin B1 supplementation on blood creatinine and lactate levels and clinical outcomes in patients in intensive care units: a systematic review and meta-analysis of randomized controlled trials

CONTEXT

The metabolic response to stress can deplete the remaining thiamine stores, leading to thiamine deficiency.

OBJECTIVE

This study is the first meta-analysis of the effectiveness of thiamine supplementation on clinical and biochemical outcomes in adult patients admitted to the intensive care unit (ICU).

DATA SOURCES

Scopus, PubMed, and Cochrane databases were searched to select studies up to 20 November 2022.

STUDY SELECTION

Studies investigating the effect of thiamine supplementation on serum lactate and creatinine levels, the need for renal replacement therapy, length of ICU stay, and mortality rate in ICU patients were selected.

DATA EXTRACTION

After excluding studies based on title and abstract screening, 2 independent investigators reviewed the full texts of the remaining articles. In the next step, a third investigator resolved any discrepancy in the article selection process.

RESULTS

Of 1628 retrieved articles, 8 were selected for final analysis. This study showed that thiamine supplementation reduced the serum creatinine level (P = .03) compared with placebo. In addition, according to subgroup analysis, serum creatinine concentration was significantly lower in patients >60 years old (P < .00001). However, there was no statistically significant difference in the lactate level between the thiamine supplementation and placebo groups (P = .26). Thiamine supplementation did not decrease the risk of all-cause mortality (P = .71) or the need for renal replacement therapy (P = .14). The pooled results of eligible randomized controlled trials also showed that thiamine supplementation did not reduce the length of ICU stay in comparison to the placebo group (P = .39).

CONCLUSION

This meta-analysis provides evidence that thiamine supplementation has a protective effect against blood creatinine increase in ICU patients. However, further high-quality trials are needed to discover the effect of thiamine supplementation on clinical and biochemical outcomes in ICU patients.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO no. CRD42023399710 (https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=399710).

Validation of a Prediction Model for Acute Kidney Injury after Cardiac Surgery in a Retrospective Asian Cohort

Background: The incidence of postoperative acute kidney injury (AKI) is relatively high in some Asian regions. The objective of this study was to examine the performance of an AKI prediction model developed based on data from a White-dominant population in a retrospective Asian cohort of patients undergoing cardiovascular surgery. Methods: We retrospectively identified 549 patients who underwent elective major cardiovascular surgery (coronary artery bypass graft, valve surgery, and aorta surgery), and excluded those who underwent a percutaneous cardiovascular procedure. Patients with a baseline estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 were also excluded. AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) definition. Performance of the prediction model for AKI was expressed as area under the receiver operating characteristic curve (AUC). Results: The prediction model had a good predictive accuracy for postoperative AKI (all AUC > 0.92). The AUC of the prediction model in subgroups of age (<65 years and ≥65 years), sex (male and female), hypertension, and diabetes were all >0.85 (all p values < 0.001). Conclusions: The model could be used to predict postoperative AKI in Asian patients undergoing cardiovascular surgery with a baseline eGFR ≥ 60 mL/min/1.73 m2.

Adverse renal effects associated with cardiopulmonary bypass

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

Plasma hyperosmolality during cardiopulmonary bypass is a risk factor for postoperative acute kidney injury: Results from double blind randomised controlled trial

INTRODUCTION

The study objective was to investigate whether a Ringer's acetate based priming solution with addition of Mannitol and sodium concentrate increases the risk of cardiac surgery associated kidney injury (CSA-AKI).

METHODS

This is a double blind, prospective randomized controlled trial from a single tertiary teaching hospital in Sweden including patients aged ≥65 years (n = 195) admitted for routine cardiac surgery with cardiopulmonary bypass. Patients in the study group received Ringer's acetate 1000 mL + 400 mL Mannitol (60 g) + sodium chloride 40 mL (160 mmol) and heparin 2 mL (10 000 IU) 966 mOsmol (n = 98), while patients in the control group received Ringer's acetate 1400 mL + heparin 2 mL (10 000 IU), 388 mOsmol (n = 97) as pump prime. Acute kidney injury was analysed based on the Kidney Disease Improving Outcomes (KDIGO 1-3) definition.

RESULTS

The overall incidence of CSA-AKI (KDIGO stage 1) was 2.6% on day 1 in the ICU and 5.6% on day 3, postoperatively. The serum creatinine level did not show any postoperative intergroup differences, when compared to baseline preoperative values. Six patients in the Ringer and five patients in the Mannitol group developed CSA-AKI (KDIGO 1-3), all with glomerular filtration rates <60 mL/min/1.73 m2. These patients showed significantly higher plasma osmolality levels compared to preoperative values. Hyperosmolality together with patient age and the duration of the surgery were independent risk factors for postoperative acute kidney injury (KDIGO 1-3).

CONCLUSIONS

The use of a hyperosmolar prime solution did not increase the incidence of postoperative CSA-AKI in this study, while high plasma osmolality alone increased the associated risk by 30%. The data suggests further examination of plasma hyperosmolality as a relative risk factor of CSA-AKI.

Preoperative serum selenium predicts acute kidney injury after adult cardiac surgery

BACKGROUND

The relationship between serum selenium (Se) and acute kidney injury after adult cardiac surgery (CSA-AKI) remains controversial. This study aimed to investigate the association of preoperative Se level with incident CSA-AKI.

METHOD AND RESULTS

A retrospective cohort study was conducted on patients who underwent cardiac surgery. The primary outcome was incident CSA-AKI. Multivariable logistic regression models and natural cubic splines were used to estimate the association of Se levels and primary outcome. A total of 453 patient with a mean age of 62.97 years were included. Among all patients, 159 (35.1%) incident cases of CSA-AKI were identified. The level of preoperative Se concentration in patients with CSA-AKI was significant lower than that in patients without CSA-AKI. The higher preoperative Se level was significantly associated with decreased risk of CSA-AKI (adjusted OR 0.91, 95% CI: 0.87-0.99). Dose-response relationship curve revealed a nearly L-shape correlation between serum Se selenium levels and incident CSA-AKI.

CONCLUSION

Our study suggested that a higher level of serum Se was significantly associated with lower risk of CSA-AKI. Further prospective studies are needed to clarify the causal relationship between serum Se level and incident CSA-AKI.

Carboxyhemoglobin in Cardiac Surgery Patients and Its Association with Risk Factors and Biomarkers of Hemolysis

BACKGROUND

Cardiac surgery with cardiopulmonary bypass (CPB) is associated with hemolysis. Yet, there is no easily available and frequently measured marker to monitor this hemolysis. However, carboxyhemoglobin (CO-Hb), formed by the binding of carbon monoxide (a product of heme breakdown) to hemoglobin, may reflect such hemolysis. We hypothesized that CO-Hb might increase after cardiac surgery and show associations with operative risk factors and indirect markers for hemolysis.

METHODS

We conducted a retrospective descriptive cohort study of data from on-pump cardiac surgery patients. We analyzed temporal changes in CO-Hb levels and applied a generalized linear model to assess patient characteristics associated with peak CO-Hb levels. Additionally, we examined their relationship with red blood cell (RBC) transfusion and bilirubin levels.

RESULTS

We studied 38,487 CO-Hb measurements in 1735 patients. CO-Hb levels increased significantly after cardiac surgery, reaching a peak CO-Hb level 2.1 times higher than baseline (P < .001) at a median of 17 hours after the initiation of surgery. Several factors were independently associated with higher peak CO-Hb, including age (P < .001), preoperative respiratory disease (P = .001), New York Heart Association Class IV (P = .019), the number of packed RBC transfused (P < .001), and the duration of CPB (P = .002). Peak CO-Hb levels also significantly correlated with postoperative total bilirubin levels (Rho = 0.27, P < .001).

CONCLUSIONS

CO-Hb may represent a readily obtainable and frequently measured biomarker that has a moderate association with known biomarkers of and risk factors for hemolysis in on-pump cardiac surgery patients. These findings have potential clinical implications and warrant further investigation.

Del Nido vs. Cold Blood Cardioplegia for High-Risk Isolated Coronary Artery Bypass Grafting in Patients with Reduced Ventricular Function

INTRODUCTION

The evidence for using del Nido cardioplegia protocol in high-risk patients with reduced ejection fraction undergoing isolated coronary surgery is insufficient.

METHODS

The institutional database was searched for isolated coronary bypass procedures. Patients with ejection fraction < 40% were selected. Propensity matching (age, sex, infarction, number of grafts) was used to pair del Nido (Group 1) and cold blood (Group 2) cardioplegia patients. Investigation of biomarker release, changes in ejection fraction, mortality, stroke, perioperative myocardial infarction, composite endpoint (major adverse cardiac and cerebrovascular events), and other perioperative parameters was performed.

RESULTS

Matching allowed the selection of 45 patient pairs. No differences were noted at baseline. After cross-clamp release, spontaneous sinus rhythm return was observed more frequently in Group 1 (80% vs. 48.9%; P=0.003). Troponin values were similar in both groups 12 and 36 hours after surgery, as well as creatine kinase at 12 hours. A trend favored Group 1 in creatine kinase release at 36 hours (median 4.9; interquartile range 3.8-9.6 ng/mL vs. 7.3; 4.5-17.5 ng/mL; P=0.085). Perioperative mortality, rates of myocardial infarction, stroke, or major adverse cardiac and cerebrovascular events were similar. No difference in postoperative ejection fraction was noted (median 35.0%; interquartile range 32.0-38.0% vs. 35.0%; 32.0-40.0%; P=0.381). There was a trend for lower atrial fibrillation rate in Group 1 (6.7% vs. 17.8%; P=0.051).

CONCLUSION

The findings indicate that del Nido cardioplegia provides satisfactory protection in patients with reduced ejection fraction undergoing coronary bypass surgery. Further prospective trials are required.

Adjusting Acute Kidney Injury Kidney Disease: Improving Global Outcomes Urine Output Criterion for Predicted Body Weight Improves Prediction of Hospital Mortality

BACKGROUND

Based on the Kidney Disease: Improving Global Outcomes (KDIGO) definitions, urine output, serum creatinine, and need for kidney replacement therapy are used for staging acute kidney injury (AKI). Currently, AKI staging correlates strongly with mortality and can be used as a predictive tool. However, factors associated with the development of AKI may affect its predictive ability. We tested whether adjustment for predicted (versus actual) body weight improved the ability of AKI staging to predict hospital mortality.

METHODS

A total of 3279 patients who had undergone cardiac surgery in a university hospital were retrospectively analyzed. AKI was staged according to KDIGO criteria (standard staging) and after adjustment for hourly urine output adjusted by predicted body weight for each patient and each day of their hospital stay.

RESULTS

The incidence of AKI (all stages) was 43% (predicted body weight adjusted) and 50% (standard staging), respectively ( P < .001). In sensitivity-specificity analyses for predicting hospital mortality, the area under the curve was significantly higher after adjustment for predicted body weight than with standard staging ( P = .002).

CONCLUSIONS

Compared to standard staging, adjustment of urine output for predicted body weight increases the specificity and improves prediction of hospital mortality in patients undergoing cardiac surgery.

Cardiac surgery-associated acute kidney injury and perioperative plasma viscosity: is there a relationship?

Plasma viscosity (PV) is a key factor in microcirculatory flow resistance and capillary perfusion during hemodilution, we hypothesized a possible relationship between cardiac surgery-associated acute kidney injury (CSA-AKI) and PV. We conducted a prospective, observational, single-center study on 50 adult cardiac surgery patients with cardiopulmonary bypass (age 64 years, male sex 80%, baseline serum creatinine 1.04 mg/dL). We assessed perioperative characteristics, management, short-term outcomes, blood analysis, PV, serum creatinine, and diuresis. CSA-AKI was identified using KDIGO criteria. Data were collected at 10 time points during the first perioperative week. CSA-AKI occurred in 17 patients (34%): 12 (24%) stage 1, 1 (2%) stage 2, and 4 (8%) stage 3. Most patients (88%) developed CSA-AKI within 48 h post-surgery. Patients with CSA-AKI had higher body mass index (BMI), more frequent chronic kidney disease (CKD), and lower hemoglobin and hematocrit levels. The median baseline PV for the entire cohort was 1.50 cP on EDTA and 1.37 cP on citrate. No significant differences in PV levels were found between patients with CSA-AKI and normal kidney function, both at baseline and at the 48-h. Logistic and Cox regression analyses showed no significant relationship between PV and CSA-AKI. However, CSA-AKI was related to increased BMI, lower hemoglobin and hematocrit levels, and pre-existing CKD. The present study found no significant association between PV and CSA-AKI. Nevertheless, more research is needed to validate this finding and to investigate the role of PV in other clinical settings.

Acute Kidney Injury after Cardiac Surgery: Prediction, Prevention, and Management

Acute kidney injury (AKI) is a common complication in cardiac surgery patients, with a reported incidence of 20 to 30%. The development of AKI is associated with worse short- and long-term mortality, and longer hospital length of stay. The pathogenesis of cardiac surgery-associated AKI is poorly understood but likely involves an interplay between preoperative comorbidities and perioperative stressors. AKI is commonly diagnosed by using increases in serum creatinine or decreased urine output and staged using a standardized definition such as the Kidney Disease Improving Global Outcomes classification. Novel biomarkers under investigation may provide earlier detection and better prediction of AKI, enabling mitigating therapies early in the perioperative period. Recent clinical trials of cardiac surgery patients have demonstrated the benefit of goal-directed oxygen delivery, avoidance of hyperthermic perfusion and specific fluid and medication strategies. This review article highlights both advances and limitations regarding the prevention, prediction, and treatment of cardiac surgery-associated AKI.

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.

TIMP-2 and IGFBP7 in human kidney biopsies in renal disease

Background

Tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7) are markers of tubular stress and urinary [TIMP-2]*[IGFBP7] is an established biomarker for risk assessment of acute kidney injury. There are no studies of expression profiles or localization of these markers in human renal tissue with confirmed renal disease.

Methods

We analysed 37 kidney biopsies of patients with renal disease and 10 non-diseased control biopsies for TIMP-2 and IGFBP7 expression using immunohistochemistry. Changes in glomerular morphology were evaluated by a semi-quantitative glomerulosclerosis score (GSI) and tubular interstitial changes were graded by the tubular injury score (TSI) using periodic acid-Schiff-stained paraffin sections. Interstitial fibrosis and tubular atrophy (IF/TA) were graded according to the Banff classification. Urinary [TIMP-2]*[IGFBP7] was collected at the time of biopsy.

Results

TIMP-2 and IGFBP7 had significantly greater expression in kidney biopsies from patients with renal disease compared with control tissue, especially in the tubular compartment. Here, IGFBP7 was detected in proximal and distal tubules while TIMP-2 was predominantly localized in the collecting ducts. Renal injury significantly correlated with staining intensity for TIMP-2 and IGFBP7: GSI weakly correlated with glomerular TIMP-2 (r = 0.36) and IGFBP7 (r = 0.35) and TSI correlated with tubular TIMP-2 (r = 0.41) and IGFBP7 (r = 0.43). Urinary [TIMP-2]*[IGFBP7] correlated weakly with the histopathological damage score but not with glomerular and tubular expression.

Conclusion

Our findings underline the role of TIMP-2/IGFBP7 as an unspecific marker of renal injury that is already in use for early detection of acute kidney injury.

Analysis of Risk Factors and Intervention Strategies for Acute Kidney Injury After Cardiac Valve Replacement

Objective

To investigate the risk factors and intervention strategies for the development of acute kidney injury (AKI) after cardiac valve replacement with extracorporeal circulation.

Methods

Retrospective analysis of the clinical data of a total of 106 patients diagnosed with heart valve disease and undergoing extracorporeal circulation heart valve replacement surgery from January 2021 to December 2021 in the Department of Cardiac and Major Vascular Surgery of our hospital. The two groups were divided into AKI and non-AKI groups according to whether acute kidney injury occurred after surgery, and the preoperative, intraoperative and postoperative clinical data were compared. Single-factor analysis and multi-factor logistic regression analysis were used to explore the risk factors for acute kidney injury after extracorporeal heart valve replacement, and to improve the prognosis by giving kidney function protection strategies as early as possible.

Results

Univariate analysis showed that age, preoperative blood creatinine >130umol/L, LVEF <45%, presence of subacute infective endocarditis (SIE), concurrent coronary artery bypass grafting (CABG), time to extracorporeal circulation, time to surgery, MAP <70mmHg, urine output <0.5mL/(kg-h), pulmonary infection, low cardiac output, and bacteraemia were risk factors for postoperative AKI. Multi-factor regression analysis showed that preoperative blood creatinine >130umol/l, LVEF <45%, combined infective endocarditis, extracorporeal circulation time >2h, intraoperative and postoperative hypotension, low cardiac output, and postoperative bacteremia were independent risk factors for postoperative AKI.

Conclusion

Active intervention strategies in the perioperative period can reduce the occurrence of postoperative AKI and improve patient prognosis.

Comparison Between Dexmedetomidine and Propofol for Sedation on Outcomes After Cardiac Surgery in Patients Requiring Mechanical Ventilation: A Meta-Analysis of Randomized-Control Trials

The aim of this study was to compare outcomes between dexmedetomidine and propofol for sedation after cardiac surgery in patients requiring mechanical ventilation. This meta-analysis was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Online databases, including EMBASE, PubMed, and the Cochrane Library, were comprehensively searched to identify relevant randomized controlled trials (RCTs) comparing the safety and efficacy of dexmedetomidine and propofol in patients undergoing cardiac surgery and requiring mechanical ventilation. The examined outcomes included the mean length of intensive care unit (ICU) stay in hours, duration of mechanical ventilation in hours, length of hospital stay in days, and number of patients diagnosed with delirium. A total of 14 studies were included in the present meta-analysis while 1360 patients undergoing cardiac surgery were involved in these studies. Pooled results showed that the duration of mechanical ventilation was lower in the dexmedetomidine group compared to the propofol group (mean difference (MD): 0.75, 95% confidence interval (CI): 0.06-1.44, p-value: 0.03). We also found a significantly low length of stay in ICU in the dexmedetomidine group compared to the propofol (MD: 0.89, 95% CI: 0.04-1.74, p-value: 0.04). The length of hospital stay was also significantly lower in patients receiving dexmedetomidine as compared to the propofol group (MD: 0.51, 95% CI: 0.32-0.70, p-value<0.001). Risk of delirium was significantly higher in patients receiving propofol compared to patients receiving dexmedetomidine (RR: 2.02, 95% CI: 1.48-2.74, p-value<0.001). In conclusion, our meta-analysis provides evidence of the beneficial impacts of dexmedetomidine on clinical outcomes in patients undergoing cardiac surgery. Dexmedetomidine was associated with a significant reduction in the duration of mechanical ventilation, length of stay in the intensive care unit (ICU) and hospital, and the risk of delirium.

Expression and Significance of KIM-1, NGAL, and HO-1 in Patients with Acute Kidney Injury After Cardiac Valve Replacement

Objective

To investigate the changes and significance of perioperative expression levels of kidney injury molecule-1 (KIM-1), neutrophil gelatinase-related lipocalin (NGAL), and heme oxygenase-1 (HO-1) in patients with acute kidney injury (AKI) after cardiac valve replacement under cardiopulmonary bypass.

Methods

A total of 80 patients were divided into the AKI group and non-AKI group based on the postoperative occurrence of AKI. The expression levels of urinary KIM-1, NGAL, serum creatinine, urea nitrogen, and HO-1 were compared between the two groups before surgery and at 12 h, 24 h, and 48 h after surgery.

Results

There were 22 patients with postoperative AKI (AKI group), the incidence of postoperative AKI were 27.5%, and there were 58 patients without AKI (non-AKI group). There was no significant difference in general clinical data between the two groups (P > 0.05). Compared between AKI group and preoperative group, KIM-1, NGAL, HO-1, blood creatinine, and BUN levels were significantly increased, with significant differences (P < 0.05). Compared with non-AKI groups, KIM-1, NGAL, HO-1, blood creatinine, and blood urea nitrogen levels increased at all time points, but the difference was not significant (P > 0.05). Compared with AKI group and non-AKI group, KIM-1, NGAL, HO-1, blood creatinine, and BUN levels increased significantly, the differences were statistically significant (P < 0.05).

Conclusion

AKI can easily occur after cardiac valve replacement and postoperative expression levels of KIM-1, NGAL, and HO-1 can be early warning indicators of postoperative AKI.

Effects of Ulinastatin on Postoperative Renal Function in Patients Undergoing Cardiac Surgery with Cardiopulmonary Bypass: A Prospective Cohort Study with 10-Year Follow-Up

INTRODUCTION

The present study aimed to explore the potential effect of ulinastatin on renal function and long-term survival in patients receiving cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

This prospective cohort study was conducted at Fuwai Hospital, Beijing, China. Ulinastatin was applied after induction anesthesia. The primary outcome was the rate of new-onset postoperative acute kidney injury (AKI). Moreover, a 10-year follow-up was conducted until January 2021.

RESULTS

The rate of new-onset AKI was significantly lower in the ulinastatin group than in the control group (20.00 vs. 32.40%, p = 0.009). There was no significant difference in renal replacement therapy between the two groups (0.00 vs. 2.16%, p = 0.09). The postoperative plasma neutrophil gelatinase-associated lipocalin (pNGAL) and IL-6 levels were significantly lower in the ulinastatin group compared with the control group (pNGAL: p = 0.007; IL-6: p = 0.001). A significantly lower incidence of respiratory failure in the ulinastatin group compared with the control group (0.76 vs. 5.40%, p = 0.02). The nearly 10-year follow-up (median: 9.37, 95% confidence interval: 9.17-9.57) survival rates did not differ significantly between the two groups (p = 0.076).

CONCLUSIONS

Ulinastatin significantly reduced postoperative AKI and respiratory failure in patients receiving cardiac surgery with CPB. However, ulinastatin did not reduce intensive care unit and hospital stays, mortality, and long-term survival rate.

Association of urine output during cardiopulmonary bypass and postoperative acute kidney injury in patients undergoing coronary artery bypass graft

Acute kidney injury (AKI) is a common complication in patients undergoing coronary artery bypass graft (CABG) surgery and is associated with significant morbidity and mortality. We investigated the association of urine output (U/O) during cardiopulmonary bypass (CPB) with postoperative AKI in a cohort of patients undergoing elective CABG.

This single-center retrospective study used data from patients undergoing elective CABG with CPB (March 2015 to March 2020). Demographic data and perioperative information were extracted from the Patients' records. Urine output during CPB and in the first 3 days after surgery was also recorded. Acute kidney injury was defined according to the Acute Kidney Injury Network (AKIN) classification. Spearman's correlation analysis was used to evaluate the relationship between quantitative variables and multiple logistic regression analysis was applied to determine AKI predictors.

A total of 532 patients with a mean age of 56.83 ± 7.99 years were analyzed. In the first 48 h after surgery, the incidence of AKI was 18%, of which, 7 (2.7%) patients developed stage II of AKI. There was no significant correlation between U/O during CPB and change in postoperative blood urea nitrogen (BUN) and creatinine. Oliguria during CPB was not observed in any of the patients. Age and duration of bypass were identified as predictors of AKI.

In this study, the incidence of AKI was 18% and there was no significant correlation between U/O during CPB and changes in postoperative BUN and creatinine. Age and duration of bypass were independent risk factors of AKI.

Cardiac surgery-associated acute kidney injury in newborns: A meta-analysis

<b>Introduction</b>: Acute kidney injury is a common complication following pediatric heart surgery, and it has been linked to an increased risk of morbidity and fatality.<br /> <b>Methods</b>: The PubMed and Medline databases were combed for relevant research until May 2022. The terms [Cardiac surgery] AND [acute renal injury] AND [newborns OR children OR neonates] AND [randomized control studies OR randomized control trials] were used as search criteria. The studies that met the inclusion criteria were considered qualified using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.<br /> <b>Results</b>: A total of 2,941 newborns or children were enrolled in 14 studies, with 931 developing acute renal damage. 2,095 of the enrolled infants and children received steroid, aminophylline, dexmedetomidine, and acetaminophen therapies. In seven studies, the odds ratio for steroids was not significantly different from control. In contrast, two studies comparing aminophylline to a control group found no statistically significant change. Two studies found no significant difference in dexmedetomidine therapy compared to control. Three trials, however, found a significant difference between the acetaminophen treatment and control groups.<br /> <b>Conclusion</b>: Acetaminophen was linked to a decreased risk of postoperative acute renal injury, while steroids had no benefit and aminophylline treatment could be justified.

Defining a postoperative mean arterial pressure threshold in association with acute kidney injury after cardiac surgery: a prospective observational study

Acute kidney injury (AKI) is a common but fatal complication after cardiac surgery. In the absence of effective treatments, the identification and modification of risk factors has been a major component of disease management. However, the optimal blood pressure target for preventing cardiac surgery-associated acute kidney injury (CSA-AKI) remains unclear. We sought to determine the effect of postoperative mean arterial pressure (MAP) in CSA-AKI. It is hypothesized that longer periods of hypotension after cardiac surgery are associated with an increased risk of AKI. This prospective cohort study was conducted on adult patients who underwent cardiac surgery requiring cardiopulmonary bypass at a tertiary center between October 2018 and May 2020. The primary outcome is the occurrence of CSA-AKI. MAP and its duration in the ranges of less than 65, 65 to 74, and 75 to 84 mmHg within 24 h after surgery were recorded. The association between postoperative MAP and CSA-AKI was examined by using logistic regression. Among the 353 patients enrolled, 217 (61.5%) had a confirmed diagnosis of CSA-AKI. Each 1 h epoch of postoperative MAP less than 65 mmHg was associated with an adjusted odds ratio of 1.208 (95% CI, 1.007 to 1.449; P = 0.042), and each 1 h epoch of postoperative MAP between 65 and 74 mmHg was associated with an adjusted odds ratio of 1.144 (95% CI, 1.026 to 1.275; P = 0.016) for CSA-AKI. A potentially modifiable risk factor, postoperative MAP less than 75 mmHg for 1 h or more is associated with an increased risk of CSA-AKI.

Del Nido versus cold blood cardioplegia in adult patients with impaired ejection fraction undergoing valvular and complex heart surgery

BACKGROUND

There is sparse evidence on the efficacy of del Nido cardioplegia in high-risk patients with reduced ejection fraction undergoing valvular or complex heart surgery, and further investigation is required.

METHODS

An institutional registry was searched for patients who underwent valvular or complex heart surgery and had an ejection fraction <40%. Subjects who received del Nido cardioplegia (DNC) and cold blood cardioplegia (CBC) were selected. Propensity matching was performed with age, gender, and number of conducted procedures as matching criteria. A comparative analysis was performed on primary endpoints of the troponin rise and changes in ejection fraction (EF). A composite endpoint of a troponin rise of ≥20× baseline or fall of EF≥5% was assessed in a multivariate analysis. Other perioperative complications are reported.

RESULTS

One hundred patients from the DNC group were matched to the 100 patients in the CBC group. There were no differences between groups at baseline. Postoperatively, lower troponin values were observed in the DNC group at 12 hours (median; IQR: 523.2;349.1-740.4 pg/mL vs. 787.6;443.6-1689.0 pg/mL; P=0.016) and 36 hours (median; IQR: 426.1;337.2-492.1 pg/mL vs. 653.7;398.8-1737.5 pg/mL; P=0.044). Fewer patients in the DNC group had a fall in EF≥5% (7% vs. 16%; P=0.046). The multivariable analysis did not reveal a significant predictor of composite endpoint.

CONCLUSIONS

In patients with impaired contractility undergoing valvular and complex procedures, the use of del Nido cardioplegia as an alternative to cold blood cardioplegia is associated with lower troponin release and improved preservation of ejection fraction.

The prognostic value of elevated neutrophil-lymphocyte ratio for cardiac surgery-associated acute kidney injury: A systematic review and meta-analysis

BACKGROUND

Patients undergoing cardiac surgery are at significant risk of developing postoperative acute kidney injury (AKI). Neutrophil-lymphocyte ratio (NLR) is a widely available inflammatory biomarker which may be of prognostic value in this setting.

METHODS

We conducted a systematic review and meta-analysis of studies reporting associations between perioperative NLR with postoperative AKI. We searched Medline, Embase and the Cochrane Library, without language restriction, from inception to May 2022 for relevant studies. We meta-analysed the reported odds ratios (ORs) with 95% confidence intervals (CIs) for both elevated preoperative and postoperative NLR with risk of postoperative AKI and need for renal replacement therapy (RRT). We conducted a meta-regression to explore inter-study statistical heterogeneity.

RESULTS

Twelve studies involving 10,724 participants undergoing cardiac surgery were included, with eight studies being deemed at high risk of bias using PROBAST modelling. We found statistically significant associations between elevated preoperative NLR and postoperative AKI (OR 1.45, 95% CI 1.18-1.77), as well as postoperative need for RRT (OR 2.37, 95% CI 1.50-3.72). Postoperative NLR measurements were not of prognostic significance.

CONCLUSIONS

Elevated preoperative NLR is a reliable inflammatory biomarker for predicting AKI following cardiac surgery.

Association between acute kidney injury and prognoses of cardiac surgery patients: Analysis of the MIMIC-III database

Background

Acute kidney injury (AKI) is the most common major complication of cardiac surgery field. The purpose of this study is to investigate the association between acute kidney injury and the prognoses of cardiac surgery patients in the Medical Information Mart for Intensive Care III (MIMIC-III) database.

Methods

Clinical data were extracted from the MIMIC-III database. Adult (≥18 years) cardiac surgery patients in the database were enrolled. Multivariable logistic regression analyses were employed to assess the associations between acute kidney injury (AKI) comorbidity and 30-day mortality, 90-day mortality and hospital mortality. Different adjusting models were used to adjust for potential confounders.

Results

A total of 6,002 patients were involved, among which 485 patients (8.08%) had comorbid AKI. Patients with AKI were at higher risks of prolonged ICU stay, hospital mortality, 90-day mortality (all P < 0.001), and 30-day mortality (P = 0.008). AKI was a risk factor for hospital mortality [Model 1, OR (95% CI) = 2.50 (1.45-4.33); Model 2, OR (95% CI) = 2.44 (1.48-4.02)], 30-day mortality [Model 1, OR (95% CI) = 1.84 (1.05-3.24); Model 2, OR (95% CI) = 1.96 (1.13-3.22)] and 90-day mortality [Model 1, OR (95% CI) = 2.05 (1.37-3.01); Model 2, OR (95% CI) = 2.76 (1.93-3.94)]. Higher hospital mortality, 30-day mortality and 90-day mortality was observed in higher KDIGO grade for cardiac surgery patients with AKI (all P < 0.05).

Conclusion

Comorbid AKI increased the risk of hospital mortality, 30-day mortality, and 90-day mortality of cardiac surgery patients in the MIMIC-III database.

The Utility of Novel Kidney Injury Biomarkers in Early Detection of CSA-AKI

Cardiac surgery-associated acute kidney injury (CSA-AKI) is one of the most common complications of cardiac surgery procedures. In this study, the authors attempt to provide new data regarding the application of novel kidney injury biomarkers in the early diagnostics of CSA-AKI. 128 adult patients undergoing elective cardiac surgery procedures with the use of cardiopulmonary by-pass (CPB) were enrolled in this study. Novel kidney injury biomarkers were marked in the plasma and urine 6 h after weaning from the CPB. A significant difference in the postoperative biomarkers' concentration between the AKI and no-AKI group was found, regarding plasma IL-8, plasma TNF-α and urine NGAL, normalized for creatinine excretion (NGAL/Cr). These were also independent predictors of CSA-AKI. An independent risk factor for CSA-AKI proved to be preoperative CKD. Plasma IL-8 and TNF-α, as well as urine NGAL/Cr, are independent early indicators of CSA-AKI and pose a promising alternative for creatinine measurements. The cut-off points for these biomarkers proposed in this investigation should be confronted with more data and revised to achieve a suitable diagnostic value.

Furosemide does not reduce the incidence of postoperative acute kidney injury in adult patients undergoing cardiac surgery: A PRISMA-compliant systematic review and meta-analysis

OBJECTIVE

Acute kidney injury (AKI) is a common complication of cardiac surgical patients, the occurrence of which is multifactorial. Furosemide is the most common loop diuretic and widely used in cardiac surgery to reduce fluid overload, increase tubular flow and urine output. It remains unknown whether furosemide affects the incidence or prognosis of cardiac surgery-induced acute kidney injury (CS-AKI). Therefore, the current study was performed to address this question.

METHODS

PubMed, Embase, Scopus, Cochrane Library, and Web of Science databases were searched for relevant studies. Primary outcomes of interest included postoperative CS-AKI incidence, need for renal replacement therapy (RRT) rate. Secondary outcomes of interest included postoperative serum creatinine (Scr) and blood urea nitrogen (BUN) levels, postoperative mechanical ventilation duration (MVD), length of stay (LOS) in intensive care unit (ICU) and in hospital, and mortality. The odds ratio (OR) and/or the weighted mean difference (WMD) with 95% confidence interval (CI) were used to pool the data.

RESULTS

Database search yielded six studies including 566 adult patients, and 283 patients were allocated into Group Furosemide and 283 into Group Control (Placebo). Heterogeneity between studies was deemed acceptable, and the publication bias was low. Meta-analysis suggested that furosemide administration in adult cardiac surgical patients had no effect on CS-AKI incidence (n = 4 trials; OR = 0.92; 95% CI: 0.37-2.30; p = .86; I²  = 57%) and need for RRT rate (n = 2 trials; OR = 4.13; 95% CI: 0.44-38.51; p = .21; I²  = 0%). Diversely, furosemide administration in adult cardiac surgical patients significantly decreased postoperative BUN level (n = 3 trials; WMD = 0.71; 95% CI: 0.10-1.33; p = .02; I²  = 0%), postoperative MVD (n = 2 trials; WMD = -3.13; 95% CI: -3.78 to -2.49; p < .00001; I²  = 0%) and postoperative LOS in ICU (n = 3 trials; WMD = -0.47; 95% CI: -0.76 to -0.18; p = .001; I²  = 0%). However, it had no significant impact on postoperative Scr level, postoperative LOS in hospital, and postoperative mortality.

CONCLUSION

This meta-analysis suggested that furosemide administration in adult cardiac surgical patients had no significant effect on CS-AKI incidence, need for RRT rate, postoperative Scr level, LOS in hospital and mortality, but could reduce postoperative BUN level, MVD, and LOS in ICU. As only a limited number of studies were included, these results should be interpreted carefully and cautiously. Future high-quality randomized controlled trials are needed to define the role of furosemide in CS-AKI prevention and management.

High versus low blood pressure targets for cardiac surgery while on cardiopulmonary bypass

BACKGROUND

Cardiac surgery is performed worldwide. Most types of cardiac surgery are performed using cardiopulmonary bypass (CPB). Cardiac surgery performed with CPB is associated with morbidities. CPB needs an extracorporeal circulation that replaces the heart and lungs, and performs circulation, ventilation, and oxygenation of the blood. The lower limit of mean blood pressure to maintain blood flow to vital organs increases in people with chronic hypertension. Because people undergoing cardiac surgery commonly have chronic hypertension, we hypothesised that maintaining a relatively high blood pressure improves desirable outcomes among the people undergoing cardiac surgery with CPB.

OBJECTIVES

To evaluate the benefits and harms of higher versus lower blood pressure targets during cardiac surgery with CPB.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search of databases was November 2021 and trials registries in January 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing a higher blood pressure target (mean arterial pressure 65 mmHg or greater) with a lower blood pressure target (mean arterial pressure less than 65 mmHg) in adults undergoing cardiac surgery with CPB.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Primary outcomes were 1. acute kidney injury, 2. cognitive deterioration, and 3. all-cause mortality. Secondary outcomes were 4. quality of life, 5. acute ischaemic stroke, 6. haemorrhagic stroke, 7. length of hospital stay, 8. renal replacement therapy, 9. delirium, 10. perioperative transfusion of blood products, and 11. perioperative myocardial infarction. We used GRADE to assess certainty of evidence.

MAIN RESULTS

We included three RCTs with 737 people compared a higher blood pressure target with a lower blood pressure target during cardiac surgery with CPB. A high blood pressure target may result in little to no difference in acute kidney injury (risk ratio (RR) 1.30, 95% confidence interval (CI) 0.81 to 2.08; I² = 72%; 2 studies, 487 participants; low-certainty evidence), cognitive deterioration (RR 0.82, 95% CI 0.45 to 1.50; I² = 0%; 2 studies, 389 participants; low-certainty evidence), and all-cause mortality (RR 1.33, 95% CI 0.30 to 5.90; I² = 49%; 3 studies, 737 participants; low-certainty evidence). No study reported haemorrhagic stroke. Although a high blood pressure target may increase the length of hospital stay slightly, we found no differences between a higher and a lower blood pressure target for the other secondary outcomes. We also identified one ongoing RCT which is comparing a higher versus a lower blood pressure target among the people who undergo cardiac surgery with CPB.

AUTHORS' CONCLUSIONS

A high blood pressure target may result in little to no difference in patient outcomes including acute kidney injury and mortality. Given the wide CIs, further studies are needed to confirm the efficacy of a higher blood pressure target among those who undergo cardiac surgery with CPB.

One-stage hybrid coronary revascularization for the treatment of multivessel coronary artery disease— Periprocedural and long-term results from the “HYBRID-COR” feasibility study

Background

The constant growth of interest in hybrid coronary artery revascularization (HCR) is apparent. Yet, few studies report outcomes of the one-stage HCR. Consequently, the status of such procedures is not adequately supported in clinical guidelines. The aim of this study was to report the safety, feasibility, and long term-outcomes of the one-stage HCR.

Methods and results

Patients were enrolled in the prospective one-stage hybrid coronary revascularization program (HYBRID-COR). They underwent a one-stage hybrid revascularization procedure while on double antiplatelet therapy (DAPT) with Ticagrelor: endoscopic atraumatic coronary artery bypass grafting (EACAB) for revascularization of the left anterior descending (LAD) artery and percutaneous intervention in non-LAD arteries with contemporary drug-eluting stents. The composite primary endpoint included MACCE (major adverse cardiac and cerebrovascular events: death, myocardial infarction, stroke, and repeated revascularization) in long-term observation. The study cohort consisted of 30 patients (68% male) with stable coronary artery disease (26.7%) and unstable angina (73.3%). Procedural success was 100%. No death, myocardial infarction (MI), or stroke were observed in the perioperative period. One patient (3.3%) required chest revision and blood transfusion due to surgical bleeding. Kidney injury was noted in two patients (6.6%). In a long-term follow-up (median; IQR: 4.25; 2.62–4.69 years), two patients (6.6%) underwent repeated revascularization and one patient (3.3%) died due to MI. The overall primary endpoint rate was 9.9%.

Conclusion

One-stage hybrid revascularization, on DAPT, is a feasible, safe, and efficient way of achieving complete revascularization in selected patients. The complication rate is low and acceptable. Further randomized trials are required.

Machine learning for the prediction of acute kidney injury in patients after cardiac surgery

Cardiac surgery-associated acute kidney injury (CSA-AKI) is the most prevalent major complication of cardiac surgery and exerts a negative effect on a patient's prognosis, thereby leading to mortality. Although several risk assessment models have been developed for patients undergoing cardiac surgery, their performances are unsatisfactory. In this study, a machine learning algorithm was employed to obtain better predictive power for CSA-AKI outcomes relative to statistical analysis. In addition, random forest (RF), logistic regression with LASSO regularization, extreme gradient boosting (Xgboost), and support vector machine (SVM) methods were employed for feature selection and model training. Moreover, the calibration capacity and differentiation ability of the model was assessed using net reclassification improvement (NRI) along with Brier scores and receiver operating characteristic (ROC) curves, respectively. A total of 44 patients suffered AKI after surgery. Fatty acid-binding protein (FABP), hemojuvelin (HJV), neutrophil gelatinase-associated lipocalin (NGAL), mechanical ventilation time, and troponin I (TnI) were correlated significantly with the incidence of AKI. RF was the best model for predicting AKI (Brier score: 0.137, NRI: 0.221), evidenced by an AUC value of 0.858 [95% confidence interval (CI): 0.792–0.923]. Overall, RF exhibited the best performance as compared to other machine learning algorithms. These results thus provide new insights into the early identification of CSA-AKI.

Goal Directed Perfusion Is Not Associated with a Decrease in Acute Kidney Injury in Patients Predicted to Be at High Risk for Acute Renal Failure after Cardiac Surgery

Small increases in serum creatinine postoperatively reflect an acute kidney injury (AKI) that likely occurred during cardiopulmonary bypass (CPB). Maintaining adequate oxygen delivery (DO₂) during CPB, known as GDP (goal-directed perfusion), improves outcomes. Whether GDP improves outcomes of patients at high risk for acute renal failure (ARF) is unknown. Forty-seven adult patients undergoing cardiac surgery with CPB utilizing GDP with Cleveland Clinic Acute Renal Failure Score of 3 or greater were compared with a matched cohort of patients operated upon using a flow-directed strategy. CPB flow in the GDP cohort was based on a DO₂ goal of 260 mL/min/m². Serum creatinine values were used to determine whether postoperative AKI occurred according to AKIN (Acute Kidney Injury Network) guidelines. We examined the distribution of all variables using proportions for categorical variables and means (standard deviations) for continuous variables and compared treatment groups using t tests for categorical variables and tests for differences in distributions for continuous and count variables. We used inverse probability of treatment weighting to adjust for treatment selection bias. In adjusted models, GDP was not associated with a decrease in AKI (odds ratio [OR]: .97; confidence interval [CI]: .62, 1.52), but was associated with higher odds of ARF (OR: 3.13; CI: 1.26, 7.79), mortality (OR: 3.35; CI: 1.14, 9.89), intensive care unit readmission (OR: 2.59; CI: 1.31, 5.15), need for intraoperative red blood cell transfusion (OR: 2.02; CI: 1.26, 3.25), and postoperative platelet transfusion (OR: 1.78; CI: 1.05, 3.01) when compared with the historic cohort. In patients who are at high risk for postoperative renal failure, GDP was not associated with a decrease in AKI when compared to the historical cohort managed traditionally by determining CPB flows based on body surface area. Surprisingly, the GDP cohort performed significantly worse than the retrospective control group in terms of ARF, mortality, intensive care unit readmission, and RBC and platelet transfusions.

Intraoperative venous congestion rather than hypotension is associated with acute adverse kidney events after cardiac surgery: a retrospective cohort study

BACKGROUND

The pathophysiological mechanisms by which venous congestion and hypotension lead to acute adverse kidney events after cardiac surgery with cardiopulmonary bypass have not been elucidated. We tested the hypothesis that intraoperative hypotension and venous congestion are associated with acute kidney injury and acute kidney disease.

METHODS

Primary exposures were venous congestion and intraoperative hypotension defined by central venous pressure ≥12, 16, or 20 mm Hg or mean arterial pressure ≤55, 65, or 75 mm Hg. The primary outcomes were acute kidney injury and acute kidney disease. Multivariable logistic regression and Cox proportional hazard models were used, adjusted for relevant confounding factors and multiple comparisons.

RESULTS

Of 5127 eligible subjects, 1070 (20.9%) and 327 (7.2%) developed acute kidney injury and acute kidney disease, respectively. The occurrence of acute kidney injury was statistically associated with both venous congestion and intraoperative hypotension. The cumulative incidence rate for new onset acute kidney disease was 1.34 (95% confidence interval [CI], 1.21-1.60) per 100 person-days. Acute kidney disease was significantly associated with each 10 min epoch of central venous pressure ≥12 mm Hg (hazard ratio [HR]=1.03; 99% CI, 1.01-1.06; P<0.001), ≥16 mm Hg (HR=1.04; 99% CI, 1.01-1.07; P<0.001), and ≥20 mm Hg (HR=1.07; 99% CI, 1.02-1.13; P<0.001). Venous congestion was associated with an 8-17% increased risk for de novo renal replacement therapy. In contrast, intraoperative hypotension was not associated with development of acute kidney disease.

CONCLUSION

Although both venous congestion and intraoperative hypotension are associated with acute kidney injury, only venous congestion correlates with acute kidney disease among patients undergoing cardiac surgery requiring cardiopulmonary bypass. The reported associations are suggestive of a pathophysiological role of venous congestion in acute kidney disease.

Nitric oxide: Clinical applications in critically ill patients

Inhaled nitric oxide (iNO) acts as a selective pulmonary vasodilator and it is currently approved by the FDA for the treatment of persistent pulmonary hypertension of the newborn. iNO has been demonstrated to effectively decrease pulmonary artery pressure and improve oxygenation, while decreasing extracorporeal life support use in hypoxic newborns affected by persistent pulmonary hypertension. Also, iNO seems a safe treatment with limited side effects. Despite the promising beneficial effects of NO in the preclinical literature, there is still a lack of high quality evidence for the use of iNO in clinical settings. A variety of clinical applications have been suggested in and out of the critical care environment, aiming to use iNO in respiratory failure and pulmonary hypertension of adults or as a preventative measure of hemolysis-induced vasoconstriction, ischemia/reperfusion injury and as a potential treatment of renal failure associated with cardiopulmonary bypass. In this narrative review we aim to present a comprehensive summary of the potential use of iNO in several clinical conditions with its suggested benefits, including its recent application in the scenario of the COVID-19 pandemic. Randomized controlled trials, meta-analyses, guidelines, observational studies and case-series were reported and the main findings summarized. Furthermore, we will describe the toxicity profile of NO and discuss an innovative proposed strategy to produce iNO. Overall, iNO exhibits a wide range of potential clinical benefits, that certainly warrants further efforts with randomized clinical trials to determine specific therapeutic roles of iNO.

One-shot cardioplegia for minimally invasive mitral valve repair-a comparison of del Nido and Bretschneider Histidine-Tryptophan-Ketoglutarate solutions

BACKGROUND

Minimally invasive procedures are demanding in terms of cardioprotection. In many leading centres Bretschneider HTK solution is used for mitral valve surgery. The study was designed to provide comparison of the del Nido and Bretschneider HTK protocol.

METHODS

Patients who underwent minimally invasive mitral valve repair for primary mitral regurgitation and received single delivery of either del Nido (Group 1) or Bretschneider HTK cardioplegia (Group 2) were matched on basis of age, gender and length of the cross-clamp time. The groups were compared in terms of major adverse cardiac and cerebrovascular events (death, myocardial infarction, stroke), high sensitivity troponin T (hs-TnT) and creatine kinase- MB isoenzyme (CK-MB) release at 12 h and 24 h following the surgery, incidence of low cardiac output syndrome (LCOS), postoperative arrhythmia, transfusions and postoperative renal function.

RESULTS

Case control matching selected 38 pairs of patients. None of patients died, nor suffered from myocardial infarction or stroke. Troponin values did not differ at 12 h (median: 281.0 pg/mL vs 313.0 pg/mL; p = .38) and 24 h (median: 261.0 pg/mL vs 299.0 pg/mL; p = .54), as well as CK-MB at 12 h (median: 25.0 ng/mL vs 29.0 ng/mL; p = .31) and 24 h (median: 11.0 ng/mL versus 9.6 ng/mL; p = .46). Difference in occurrence of LCOS was insignificant (2 vs 7; 5.2% vs 18.4%; p =.15). No difference was shown in incidence of postoperative arrhythmia, transfusions and renal function.

CONCLUSIONS

Del Nido cardioplegia can be used safely as an alternative for Bretschneider HTK for minimally invasive mitral valve surgery.

Effects of perioperative erythropoietin administration on acute kidney injury and red blood cell transfusion in patients undergoing cardiac surgery: A systematic review and meta-analysis

BACKGROUND

The renoprotective effects of erythropoietin (EPO) are well-known; however, the optimal timing of EPO administration remains controversial. Red blood cell (RBC) transfusion is an independent risk factor for cardiac surgery-associated acute kidney injury (CSA-AKI). We aimed to evaluate the efficacy of EPO on CSA-AKI and RBC transfusion according to the timing of administration.

METHODS

We searched the Cochrane Library, EMBASE, and MEDLINE databases for randomized controlled trials. The primary outcome was the incidence of CSA-AKI following perioperative EPO administration, and the secondary outcomes were changes in serum creatinine, S-cystatin C, S-neutrophil gelatinase-associated lipocalin, urinary neutrophil gelatinase-associated lipocalin, length of hospital and intensive care unit (ICU) stay, volume of RBC transfusion, and mortality. The subgroup analysis was stratified according to the timing of EPO administration in relation to surgery.

RESULTS

Eight randomized controlled trials with 610 patients were included in the study. EPO administration significantly decreased the incidence of CSA-AKI (odds ratio: 0.60, 95% confidence interval [CI]: 0.43-0.85, P = .004; I2 = 52%; P for heterogeneity = .04), intra-operative RBC transfusion (standardized mean difference: -0.30, 95% CI: -0.55 to -0.05, P = .02; I2 = 15%, P for heterogeneity = .31), and hospital length of stay (mean difference: -1.54 days, 95% CI: -2.70 to -0.39, P = .009; I2 = 75%, P for heterogeneity = .001) compared with control groups. Subgroup analyses revealed that pre-operative EPO treatment significantly reduced the incidence of CSA-AKI, intra-operative RBC transfusion, serum creatinine, and length of hospital and ICU stay.

CONCLUSION

Pre-operative administration of EPO may reduce the incidence of CSA-AKI and RBC transfusion, but not in patients administered EPO during the intra-operative or postoperative period. Therefore, pre-operative EPO treatment can be considered to improve postoperative outcomes by decreasing the length of hospital and ICU stay in patients undergoing cardiac surgery.

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.

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.

Perioperative albuminuria and clinical model to predict acute kidney injury in paediatric cardiac surgery

BACKGROUND

AKI is an important complication post cardiac surgery in children. An early diagnosis can help in mitigating complications and allow for prognostication. Urinary albumin:creatinine ratio (ACR) as a biomarker can provide a cheaper and more accessible AKI risk assessment and prediction. There is a paucity of paediatric literature regarding its utility.

METHODS

This was a prospective observational study, enrolling all children aged 1 month to 18 years, who underwent cardiac surgery, with use of cardiopulmonary bypass. Cohort was divided into groups < 2 years and ≥ 2 years for analyses to account for differences in physiological albumin excretion with age.

RESULTS

Of 143 children enrolled in the study, 36 developed AKI. In both age groups, the post-operative ACR was higher than pre-operative ACR among patients with and without AKI. In the group aged ≥ 2 years, the highest first post-operative ACR tertile (> 75.8 mg/g) predicted post-operative AKI after adjusting for clinical variables (adjusted RR, 11.71; 1.85-16.59). In the group aged < 2 years, the highest first post-operative ACR tertile (> 141.3 mg/g) predicted post-operative AKI in unadjusted analysis but not after adjusting for clinical variables (RR, 2.78; 0.70-6.65). For AKI risk prediction, AUC (95% CI) was highest after combining clinical model and pre-operative ACR for groups aged < 2 years [0.805 (0.713-0.896)] and ≥ 2 years [0.872 (0.772-0.973)].

CONCLUSIONS

This study provides evidence for use of albuminuria as a feasible biomarker in AKI prediction in children post cardiac surgery, especially when added to a clinical model. A higher resolution version of the Graphical abstract is available as Supplementary information.

Low Triiodothyronine Syndrome Increased the Incidence of Acute Kidney Injury After Cardiac Surgery

Background

Acute kidney injury (AKI) is a severe complication of cardiac surgery. This study was designed to explore the association between the preoperative low T3 syndrome and cardiac surgery-associated acute kidney injury (CSA-AKI).

Methods

This was a retrospective single-center study. Data on 784 patients undergoing elective coronary artery bypass grafting (CABG) or valve surgery were collected from January 2016 to July 2019. AKI was defined according to Kidney Disease: Improving Global Outcomes guidelines. The effect of preoperative low T3 syndrome (fT3 < 3.5pmol/L) on the risk of the postoperative AKI was analyzed in a logistic regression model.

Results

There were 171 (21.8%) patients developing AKI. Preoperative T3 and FT3 levels were lower in patients with AKI than in those without AKI (P < 0.001). The incidence of postoperative AKI was higher in patients with low T3 syndrome than in those without (31.0% vs 19.8%; P = 0.003). Multivariate logistic regression analysis showed that low T3 syndrome was an independent risk factor for CSA-AKI patients (OR = 1.609, 95% CI: 1.033–2.504; P = 0.035), after adjusting for confounding factors, such as age, albumin, and uric acid. Subgroup analyses showed that preoperative low T3 syndrome also increased incidence of CSA-AKI in those with high risk factors, such as age ≧60 yrs (OR: 1.891, 95% CI: 1.183–3.022, P = 0.008), hypertension (OR: 2.104, 95% CI: 1.218–3.3.635, P = 0.008), and hyperuricemia (OR: 2.052, 95% CI: 1.037–4.06, P = 0.039).

Conclusion

Low T3 syndrome independently increases the risk of CSA-AKI. Patients with low T3 syndrome should be considered at higher risk and be evaluated before cardiac surgery.

Renal and Cerebral Hypoxia and Inflammation During Cardiopulmonary Bypass

Cardiac surgery-associated acute kidney injury and brain injury remain common despite ongoing efforts to improve both the equipment and procedures deployed during cardiopulmonary bypass (CPB). The pathophysiology of injury of the kidney and brain during CPB is not completely understood. Nevertheless, renal (particularly in the medulla) and cerebral hypoxia and inflammation likely play critical roles. Multiple practical factors, including depth and mode of anesthesia, hemodilution, pump flow, and arterial pressure can influence oxygenation of the brain and kidney during CPB. Critically, these factors may have differential effects on these two vital organs. Systemic inflammatory pathways are activated during CPB through activation of the complement system, coagulation pathways, leukocytes, and the release of inflammatory cytokines. Local inflammation in the brain and kidney may be aggravated by ischemia (and thus hypoxia) and reperfusion (and thus oxidative stress) and activation of resident and infiltrating inflammatory cells. Various strategies, including manipulating perfusion conditions and administration of pharmacotherapies, could potentially be deployed to avoid or attenuate hypoxia and inflammation during CPB. Regarding manipulating perfusion conditions, based on experimental and clinical data, increasing standard pump flow and arterial pressure during CPB appears to offer the best hope to avoid hypoxia and injury, at least in the kidney. Pharmacological approaches, including use of anti-inflammatory agents such as dexmedetomidine and erythropoietin, have shown promise in preclinical models but have not been adequately tested in human trials. However, evidence for beneficial effects of corticosteroids on renal and neurological outcomes is lacking. © 2021 American Physiological Society. Compr Physiol 11:1-36, 2021.

The impact of relative hypotension on acute kidney injury progression after cardiac surgery: a multicenter retrospective cohort study

BACKGROUND

Cardiac surgery is performed worldwide, and acute kidney injury (AKI) following cardiac surgery is a risk factor for mortality. However, the optimal blood pressure target to prevent AKI after cardiac surgery remains unclear. We aimed to investigate whether relative hypotension and other hemodynamic parameters after cardiac surgery are associated with subsequent AKI progression.

METHODS

We retrospectively enrolled adult patients admitted to 14 intensive care units after elective cardiac surgery between January and December 2018. We defined mean perfusion pressure (MPP) as the difference between mean arterial pressure (MAP) and central venous pressure (CVP). The main exposure variables were time-weighted-average MPP-deficit (i.e., the percentage difference between preoperative and postoperative MPP) and time spent with MPP-deficit > 20% within the first 24 h. We defined other pressure-related hemodynamic parameters during the initial 24 h as exploratory exposure variables. The primary outcome was AKI progression, defined as one or more AKI stages using Kidney Disease: Improving Global Outcomes' creatinine and urine output criteria between 24 and 72 h. We used multivariable logistic regression analyses to assess the association between the exposure variables and AKI progression.

RESULTS

Among the 746 patients enrolled, the median time-weighted-average MPP-deficit was 20% [interquartile range (IQR): 10-27%], and the median duration with MPP-deficit > 20% was 12 h (IQR: 3-20 h). One-hundred-and-twenty patients (16.1%) experienced AKI progression. In the multivariable analyses, time-weighted-average MPP-deficit or time spent with MPP-deficit > 20% was not associated with AKI progression [odds ratio (OR): 1.01, 95% confidence interval (95% CI): 0.99-1.03]. Likewise, time spent with MPP-deficit > 20% was not associated with AKI progression (OR: 1.01, 95% CI 0.99-1.04). Among exploratory exposure variables, time-weighted-average CVP, time-weighted-average MPP, and time spent with MPP < 60 mmHg were associated with AKI progression (OR: 1.12, 95% CI 1.05-1.20; OR: 0.97, 95% CI 0.94-0.99; OR: 1.03, 95% CI 1.00-1.06, respectively).

CONCLUSIONS

Although higher CVP and lower MPP were associated with AKI progression, relative hypotension was not associated with AKI progression in patients after cardiac surgery. However, these findings were based on exploratory investigation, and further studies for validating them are required. Trial Registration UMIN-CTR, https://www.umin.ac.jp/ctr/index-j.htm , UMIN000037074.

Surgical trauma is associated with renal immune cell activation in rats: A microarray study

Acute kidney injury (AKI) is a common perioperative complication that is associated with increased mortality. This study investigates the renal gene expression in male Long-Evans rats after prolonged anesthesia and surgery to detect molecular mechanisms that could predispose the kidneys to injury upon further insults. Healthy and streptozotocin diabetic rats that underwent autoregulatory investigation in an earlier study were compared to rats that were sacrificed quickly for mRNA quantification in the same study. Prolonged surgery caused massive changes in renal mRNA expression by microarray analysis, which was validated by quantitative real-time PCR with good correlation. Furthermore, bioinformatics analysis using gene ontology and pathway analysis identified biological processes involved in immune system activation, such as immune system processes (p = 1.3 × 10-80 ), immune response (p = 1.3 × 10-60 ), and regulation of cytokine production (p = 1.7 × 10-52 ). PCR analysis of specific cell type markers indicated that the gene activation in kidneys was most probably macrophages, while granulocytes and T cell appeared less activated. Immunohistochemistry was used to quantify immune cell infiltration and showed no difference between groups indicating that the genetic activation depends on the activation of resident cells, or infiltration of a relatively small number of highly activated cells. In follow-up experiments, surgery was performed on healthy rats under standard and sterile condition showing similar expression of immune cell markers, which suggests that the inflammation was indeed caused by the surgical trauma rather than by bacterial infection. In conclusion, surgical trauma is associated with rapid activation of immune cells, most likely macrophages in rat kidneys.

Under-recognition of Acute Kidney Injury after Cardiac Surgery in the ICU Impedes Early Detection and Prevention

BACKGROUND

Acute kidney injury (AKI) is associated with high morbidity and mortality; therefore, prevention is important. The aim of this study was to systematically assess AKI incidence after cardiac surgery as documented in clinical routine compared to the real incidence because AKI may be under-recognized in clinical practice. Further, its postoperative management was compared to Kidney Disease: Improving Global Outcomes (KDIGO) recommendations because recognition and adequate treatment represent the fundamental cornerstone in the prevention and management of AKI.

METHODS

This retrospective single-center study included n = 100 patients who underwent cardiac surgery with cardiopulmonary bypass. The coded incidence of postoperative AKI during intensive care unit stay after surgery was compared to the real AKI incidence. Furthermore, conformity of postoperative parameters with KDIGO recommendations for AKI prevention and management was reviewed.

RESULTS

We found a considerable discrepancy between coded and real incidence, and conformity with KDIGO recommendations was found to be relatively low. The coded incidence was significantly lower (n = 12 vs. n = 52, p < 0.05), representing a coding rate of 23.1%. Regarding postoperative management, 90% of all patients had at least 1 episode with mean arterial pressure <65 mm Hg within the first 72 h. Furthermore, regarding other preventive parameters (avoiding hyperglycemia, stopping angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, avoiding contrast media, and nephrotoxic drugs), only 10 patients (20.8%) in the non-AKI group and in 5 (9.6%) subjects in the AKI group had none of all the above potential AKI-promoting factors.

CONCLUSIONS

AKI recognition in everyday clinical routine seems to be low, especially in lower AKI stages, and the current postoperative management still offers potential for optimization. Possibly, higher AKI awareness and stricter postoperative management could already achieve significant effects in prevention and treatment of AKI.

Perioperative Doppler measurements of renal perfusion are associated with acute kidney injury in patients undergoing cardiac surgery

Acute kidney injury (AKI) is a frequent and severe complication in cardiac surgery. Normal renal function is dependent on adequate renal perfusion, which may be altered in the perioperative period. Renal perfusion can be assessed with Doppler measurement. We aimed to determine the association between Doppler measurements of renal perfusion and the development of AKI. This was a prospective, observational study of 100 patients with ≥ one risk factor for postoperative AKI undergoing open-heart surgery. Doppler ultrasound examinations were performed before surgery and on the first and fourth postoperative day. AKI was defined according to the KDIGO criteria and subdivided into mild (KDIGO stage 1) and severe AKI (KDIGO stage 2 + 3). Thirty-three patients developed AKI, 25 developed mild and eight developed severe AKI. Abnormal renal venous flow pattern on the first postoperative day was significantly associated with the development of severe AKI (OR 8.54 (95% CI 1.01; 72.2), P = 0.046), as were portal pulsatility fraction (OR 1.07 (95% CI 1.02; 1.13), P = 0.005). Point-of-care Doppler ultrasound measurements of renal perfusion are associated with the development of AKI after cardiac surgery. Renal and portal Doppler ultrasonography can be used to identify patients at high risk or very low risk of AKI after cardiac surgery.

Incidence of acute kidney injury post cardiac surgery: a comparison of the AKIN and KDIGO criteria

Background and objectives

Data on urine output have not been routinely presented to define cardiac surgery-related acute kidney injury (AKI). We evaluated the incidence of AKI after cardiac surgery based on the AKIN and KDIGO criteria (considering serum creatinine concentration and urine output in the first 72 hours postoperatively) and compared the performance of the 2 criteria for AKI staging.

Methods

This was a prospective cohort study of adult patients undergoing coronary artery bypass grafting (CABG), valve replacement, or CABG + valve replacement between October 2017 and April 2018 at a single institution. Patients were excluded if baseline creatinine concentration (measured within 7 days before surgery) was ≥ 2.5 mg.dL^-1. Patients were evaluated for the development of AKI based on changes in urine output and serum creatinine concentration, measured daily from postoperative day 1 to 7, according to the AKIN and KDIGO criteria, which were then compared.

Results

A total of 198 patients were included. AKI occurred in 83.8% by AKIN and in 82.8% by KDIGO, when using both urine output and serum creatinine concentration as defining criteria. Using serum creatinine concentration alone, the incidence of AKI fell to 27.3% by AKIN and to 24.7% by KDIGO. A kappa coefficient of 0.98 was obtained between the AKIN and KDIGO criteria.

Conclusions

Almost perfect agreement was found between AKIN and KDIGO. AKI may be underdiagnosed after cardiac surgery if serum creatinine concentration is used as the only defining criterion. Our findings underscore the fundamental importance of using the urine output criterion in the assessment of patients at risk for AKI.

Assessment and Prognosis in CSA-AKI Using Novel Kidney Injury Biomarkers: A Prospective Observational Study

BACKGROUND

There is a need for early diagnostic solutions for cardiac surgery associated acute kidney injury (CSA-AKI) as serum creatinine changes do not occur dynamically enough. Moreover, new approaches are needed for kidney protective strategy in patients undergoing cardiac surgery procedures; Methods: Samples of serum and urine were taken from the selected group of patients undergoing elective cardiac surgery procedures. The aim of this study was to assess the utility of specific inflammation and kidney injury biomarkers in the early diagnostic of CSA-AKI and in the prognosis of long-term postoperative kidney function; Results: At 6 h after weaning from cardiopulmonary bypass, there were significant differences in IL-6, IL-8, TNF-α, MMP-9 and NGAL concentrations in patients with CSA-AKI, compared to the control group. Serum IL-8 and urine NGAL 6 h after weaning from CPB proved to be independent acute kidney injury predictors. The TNF-α, MMP-9, IL-18, TIMP-1 and MMP-9/TIMP-1 ratio in the early postoperative period correlated with long-term kidney function impairment; Conclusions: Novel kidney injury biomarkers are an eligible tool for early diagnosis of CSA-AKI. They are also reliable indicators of long-term postoperative kidney function impairment risk after cardiac surgery procedures.