Acute renal failure following cardiopulmonary bypass: a changing picture

Secreted Cytokines within the Urine of AKI Patients Modulate TP53 and SIRT1 Levels in a Human Podocyte Cell Model

Acute kidney injury (AKI) is a major kidney disease with a poor clinical outcome. It is a common complication, with an incidence of 10-15% of patients admitted to hospital. This rate even increases for patients who are admitted to the intensive care unit, with an incidence of >50%. AKI is characterized by a rapid increase in serum creatinine, decrease in urine output, or both. The associated symptoms include feeling sick or being sick, diarrhoea, dehydration, decreased urine output (although occasionally the urine output remains normal), fluid retention causing swelling in the legs or ankles, shortness of breath, fatigue and nausea. However, sometimes acute kidney injury causes no signs or symptoms and is detected by lab tests. Therefore, the identification of cytokines for the early detection and diagnosis of AKI is highly desirable, as their application might enable the prevention of the progression from AKI to chronic kidney disease (CKD). In this study, we analysed the secretome of the urine of an AKI patient cohort by employing a kidney-biomarker cytokine assay. Based on these results, we suggest ADIPOQ, EGF and SERPIN3A as potential cytokines that might be able to detect AKI as early as 24 h post-surgery. For the later stages, as common cytokines for the detection of AKI in both male and female patients, we suggest VEGF, SERPIN3A, TNFSF12, ANPEP, CXCL1, REN, CLU and PLAU. These cytokines in combination might present a robust strategy for identifying the development of AKI as early as 24 h or 72 h post-surgery. Furthermore, we evaluated the effect of patient and healthy urine on human podocyte cells. We conclude that cytokines abundant in the urine of AKI patients trigger processes that are needed to repair the damaged nephron and activate TP53 and SIRT1 to maintain the balance between proliferation, angiogenesis, and cell cycle arrest.

Urine metabolites for preoperative prediction of acute kidney injury after coronary artery bypass graft surgery

OBJECTIVE

Acute kidney injury is a common complication after on-pump coronary artery bypass grafting. Prediction of acute kidney injury remains a challenge. Our study aims to identify a panel of urine metabolites for preoperative warning of acute kidney injury after on-pump coronary artery bypass grafting.

METHODS

A total of 159 patients undergoing isolated on-pump coronary artery bypass grafting were enrolled from July 7, 2017, to May 17, 2019. Preoperative urine samples were analyzed with the approach of liquid chromatography-mass spectrometry-based urine metabolomics. The study end point was the episode of acute kidney injury within 48 hours postoperatively. The predictive performance was determined by the area under the curve and calibration curve. The results were validated using bootstrap resampling.

RESULTS

The acute kidney injury (n = 55) and nonacute kidney injury (n = 104) groups showed significant different metabolic profiling. A total of 28 metabolites showed significant differences between the acute kidney injury and nonacute kidney injury groups. A metabolite panel of 5 metabolites (tyrosyl-gamma-glutamate, deoxycholic acid glycine conjugate, 5-acetylamino-6-amino-3-methyluracil, arginyl-arginine, and L-methionine) was discovered to have a good predicting performance (area under the curve, 0.89; 95% confidence interval, 0.82-0.93), which is higher than the clinical factor-based model (area under the curve, 0.63; 95% confidence interval, 0.53-0.72). Internal validation by bootstrap resampling showed an adjusted area under the curve of 0.88, and the calibration curve demonstrated good agreement between prediction and observation in the probability of postoperative acute kidney injury. Decision curve analysis revealed a superior net benefit of the metabolite model over the traditional clinical factor-based model.

CONCLUSIONS

We present 5 urine metabolites related to acute kidney injury after coronary artery bypass grafting. This metabolite model may serve as a preoperative warning of acute kidney injury after on-pump coronary artery bypass grafting.

Acute Kidney Injury After Open Heart Surgery

Introduction: Acute kidney injury (AKI) is a term used to describe when the kidney loses its function rapidly. And it’s associated with an increase in the level of serum creatinine by 0.5 to 1mg/dL. It can be diagnosed by a plethora of criteria such as the Kidney Disease Improving Global Outcomes (KDIGO) and the Risk, Injury, Failure, Loss, End-stage (RIFLE) criteria. Cardiac surgery-associated AKI (CSA-AKI) is the most prevalent complication in patients following cardiac surgery and is also linked to increased mortality and morbidity rates. In addition, exogenous and endogenous toxins, ischemia and reperfusion, inflammation, oxidative stress, metabolic factors, and neurohormonal activation may all play a role in the development of CSA-AKI. All these factors may be active at varying time intervals and with different degrees of intensity, or may function simultaneously. 

Methods: In late 2019, a retrospective study was conducted by reviewing the health data of patients who underwent coronary artery bypass graft (CABG), valvular repairs, and other open cardiac surgeries at the King Abdulaziz University Hospital (KAUH), Jeddah, Saudi Arabia, between November 2014 and June 2019. Information was obtained from the Hospital information system, Jeddah, Saudi Arabia. Of the 159 patients who underwent open-heart surgery at KAUH, 126 (79.2%) were male and 33 (20.8%) were female. Patients below 15 years of age and those with poor renal function prior to open cardiac surgery were excluded. The KDIGO criteria were used to diagnose AKI for our patients.

Results: In this study, 34% of the patients experienced AKI after open cardiac surgery, and the most frequent risk factor encountered was diabetes mellitus (DM), which was present in 97 (61%) patients, followed by angina pectoris in 93 (58.5%) patients. Hypertension was identified in 85 (53.5%) and acute myocardial infarction in 82 (51.6%) patients. There were only two (1.3%) patients with known cases of chronic obstructive lung disease (COPD). Of the surgeries, 131 (82.4%) were classified as elective and 28 (17.6%) were urgent.

Conclusion: The most common risk factor associated with AKI following open-heart surgery is DM, followed by angina pectoris. However, further studies are required to investigate all the cardiac procedures.

Cardiac Surgery Associated AKI Prevention Strategies and Medical Treatment for CSA-AKI

Acute kidney injury (AKI) is common after cardiac surgery. To date, there are no specific pharmacological therapies. In this review, we summarise the existing evidence for prevention and management of cardiac surgery-associated AKI and outline areas for future research. Preoperatively, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers should be withheld and nephrotoxins should be avoided to reduce the risk. Intraoperative strategies include goal-directed therapy with individualised blood pressure management and administration of balanced fluids, the use of circuits with biocompatible coatings, application of minimally invasive extracorporeal circulation, and lung protective ventilation. Postoperative management should be in accordance with current KDIGO AKI recommendations.

Postoperative acute kidney injury requiring continuous renal replacement therapy and outcomes after coronary artery bypass grafting: a nationwide cohort study

BACKGROUND

Previous studies reported that patients with acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT) after cardiac surgery were at a higher risk of postoperative mortality. However, the impact of AKI and CRRT on long-term mortality has not yet been identified. Therefore, we investigated whether postoperative AKI requiring CRRT was associated with one-year all-cause mortality after coronary artery bypass grafting (CABG).

METHODS

For this population-based cohort study, we analyzed data from the National Health Insurance Service database in South Korea. The cohort included all adult patients diagnosed with ischemic heart disease who underwent isolated CABG between January 2012 and December 2017.

RESULTS

A total of 15,115 patients were included in the analysis, and 214 patients (1.4%) required CRRT for AKI after CABG during hospitalization. They received CRRT at 3.1 ± 8.5 days after CABG, for 3.1 ± 7.8 days. On multivariable Cox regression, the risk of 1-year all-cause mortality in patients who underwent CRRT was 7.69-fold higher. Additionally, on multivariable Cox regression, the 30-day and 90-day mortality after CABG in patients who underwent CRRT were 18.20-fold and 20.21-fold higher than the normal value, respectively. Newly diagnosed chronic kidney disease (CKD) requiring renal replacement therapy (RRT) 1 year after CABG in patients who underwent CRRT was 2.50-fold higher. In the generalized log-linear Poisson model, the length of hospital stay (LOS) in patients who underwent CRRT was 5% longer.

CONCLUSIONS

This population-based cohort study showed that postoperative AKI requiring CRRT was associated with a higher 1-year all-cause mortality after CABG. Furthermore, it was associated with a higher rate of 30-day and 90-day mortality, longer LOS, and higher rate of CKD requiring RRT 1 year after CABG. Our results suggest that CRRT-associated AKI after CABG may be associated with an increased risk of mortality; hence, there should be interventions in these patients after hospital discharge.

Rationale and Design of Assessing the Effectiveness of Short-Term Low-Dose Lithium Therapy in Averting Cardiac Surgery-Associated Acute Kidney Injury: A Randomized, Double Blinded, Placebo Controlled Pilot Trial

Background: Burgeoning pre-clinical evidence suggests that therapeutic targeting of glycogen synthase kinase 3β (GSK3β), a convergence point of multiple cellular protective signaling pathways, confers a beneficial effect on acute kidney injury (AKI) in experimental models. However, it remains unknown if GSK3β inhibition likewise mitigates AKI in humans. Cardiac surgery associated acute kidney injury (CSA-AKI) poses a significant challenge for clinicians and currently the only treatment available is general supportive measures. Lithium, an FDA approved mood stabilizer, is the best-known GSK3β inhibitor and has been safely used for over half a century as the first line regimen to treat bipolar affective disorders. This study attempts to examine the effectiveness of short term low dose lithium on CSA-AKI in human patients.

Methods/Design: This is a single center, prospective, randomized, double blinded, placebo controlled pilot study on patients undergoing cardiac surgery with cardiopulmonary bypass. Patients will be randomized to receive a small dose of lithium or placebo treatment for three consecutive days. Renal function will be measured via creatinine as well as novel AKI biomarkers. The primary outcome is incidence of AKI according to Acute Kidney Injury Network (AKIN) criteria, and secondary outcomes include receipt of new dialysis, days on dialysis, days on mechanical ventilation, infections within 1 month of surgery, and death within 90 days of surgery.

Discussion: As a standard selective inhibitor of GSK3β, lithium has been shown to exert a beneficial effect on tissue repair and regeneration upon acute injury in multiple organ systems, including the central nervous system and hematopoietic system. In experimental AKI, lithium at small doses is able to ameliorate AKI and promote kidney repair. Successful completion of this study will help to assess the effectiveness of lithium in CSA-AKI and could potentially pave the way for large-scale randomized trials to thoroughly evaluate the efficacy of this novel regimen for preventing AKI after cardiac surgery.

Trial Registration: This study was registered prospectively on the 17th February 2017 at ClinicalTrials.gov (NCT03056248, https://clinicaltrials.gov/ct2/show/NCT03056248?term=NCT03056248&draw=2&rank=1).

Repeat Coronary Artery Bypass Grafting: A Meta-Analysis of Off-Pump versus On-Pump Techniques in a Large Cohort of Patients

BACKGROUND

Redo coronary artery bypass grafting (CABG) can be performed with either the off-pump (OPCAB) or the on-pump (ONCAB) technique.

METHOD

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), this meta-analysis compared the safety and efficacy of OPCAB versus ONCAB redo CABG.

RESULTS

Twenty-three (23) eligible studies were included (OPCAB, n=2,085; ONCAB, n=3,245). Off-pump CABG significantly reduced the risk of perioperative death (defined as in-hospital or 30-day death rate), myocardial infarction, atrial fibrillation, and acute kidney injury. The two treatment approaches were comparable regarding 30-day stroke and late all-cause mortality.

CONCLUSIONS

Off-pump redo CABG resulted in lower perioperative death and periprocedural complication rates. No difference was observed in perioperative stroke rates and long-term survival between the two techniques.

Acute Kidney Injury following Cardiopulmonary Bypass: A Challenging Picture

Recent studies have recognized several risk factors for cardiopulmonary bypass- (CPB-) associated acute kidney injury (AKI). However, the lack of early biomarkers for AKI prevents practitioners from intervening in a timely manner. We reviewed the literature with the aim of improving our understanding of the risk factors for CPB-associated AKI, which may increase our ability to prevent or improve this condition. Some novel early biomarkers for AKI have been introduced. In particular, a combinational use of these biomarkers would be helpful to improve clinical outcomes. Furthermore, we discuss several interventions that are aimed at managing CPB-associated AKI, may increase the effect of renal replacement therapy (RRT), and may contribute to preventing CPB-associated AKI. Collectively, the conclusions of this paper are limited by the availability of clinical trial evidence and conflicting definitions of AKI. A guideline is urgently needed for CPB-associated AKI.

Red-Colored Urine in the Cardiac Surgical Patient-Diagnosis, Causes, and Management

Red-colored urine occurring in the intraoperative and early postoperative periods after cardiac surgery is often a cause for concern. This observation may be a result of hematuria from pathology within the urinary tract, anticoagulant-related nephropathy, drug-induced acute interstitial nephropathy, excretion of heme pigment-containing proteins, such as myoglobin and hemoglobin, and hemolysis occurring during extracorporeal circulation. Within the kidneys, heme-containing compounds result in pigment nephropathy, which is a significant contributory factor to cardiac surgery-associated acute kidney injury. Concerted efforts to reduce red blood cell damage during cardiopulmonary bypass, together with early recognition of the at-risk patient and the institution of prompt therapeutic intervention, may improve outcomes. This review addresses the diagnosis, causes, and management of red-discolored urine occurring during and after cardiac surgery.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Changing epidemiology and outcomes of acute kidney injury in Brazilian patients: a retrospective study from a teaching hospital

PURPOSE

While considerable information is available on acute kidney injury (AKI) in North America and Europe, large comprehensive epidemiologic studies on AKI from Latin America and Asia are still lacking. The present study aimed to evaluate the epidemiology and outcomes of AKI in patients evaluated by nephrologists in a Brazilian teaching hospital.

METHODS

We performed a large retrospective observational study that looked into the epidemiology of AKI and its effect on patient outcomes across time periods. For comparison purposes, patients were divided into two groups according to the year of follow up: 2011-2014 and 2015-2018.

RESULTS

We enrolled 7976 AKI patients and, after excluding patients with chronic kidney disease stages 4 and 5, kidney transplant recipients and those with incomplete data, 5428 AKI patients were included (68%). The maximum AKI stage was 3 (50.6%), and there was a mortality rate of 34.3% (1865 patients). Dialysis treatment was indicated in 928 patients (17.1%). Patient survival improved along the study periods, and patients treated in 2015-2018 had a relative risk death reduction of 0.89 (95% CI 0.81-0.98, p = 0.02). The independent risk factors for mortality were sepsis, > 65 years of age, admission to the intensive care unit, AKI-KDIGO 3, recurrent AKI, no metabolic and fluid demand to capacity imbalance (as a dialysis indication), and the period of treatment.

CONCLUSION

We observed an improvement in AKI patient survival over the years, even after correction for several confounders and using a competing risk approach. Identification of risk factors for mortality can help in decision-making for timely intervention, leading to better clinical outcomes.

Biomarker-guided implementation of the KDIGO guidelines to reduce the occurrence of acute kidney injury in patients after cardiac surgery (PrevAKI-multicentre): protocol for a multicentre, observational study followed by randomised controlled feasibility trial

INTRODUCTION

Acute kidney injury (AKI) is a frequent complication after cardiac surgery with adverse short-term and long-term outcomes. Although prevention of AKI (PrevAKI) is strongly recommended, the optimal strategy is uncertain. The Kidney Disease: Improving Global Outcomes (KDIGO) guideline recommended a bundle of supportive measures in high-risk patients. In a single-centre trial, we recently demonstrated that the strict implementation of the KDIGO bundle significantly reduced the occurrence of AKI after cardiac surgery. In this feasibility study, we aim to evaluate whether the study protocol can be implemented in a multicentre setting in preparation for a large multicentre trial.

METHODS AND ANALYSIS

We plan to conduct a prospective, observational survey followed by a randomised controlled, multicentre, multinational clinical trial including 280 patients undergoing cardiac surgery with cardiopulmonary bypass. The purpose of the observational survey is to explore the adherence to the KDIGO recommendations in routine clinical practice. The second phase is a randomised controlled trial. The objective is to investigate whether the trial protocol is implementable in a large multicentre, multinational setting. The primary endpoint of the interventional part is the compliance rate with the protocol. Secondary endpoints include the occurrence of any AKI and moderate/severe AKI as defined by the KDIGO criteria within 72 hours after surgery, renal recovery at day 90, use of renal replacement therapy (RRT) and mortality at days 30, 60 and 90, the combined endpoint major adverse kidney events consisting of persistent renal dysfunction, RRT and mortality at day 90 and safety outcomes.

ETHICS AND DISSEMINATION

The PrevAKI multicentre study has been approved by the leading Research Ethics Committee of the University of Münster and the respective Research Ethics Committee at each participating site. The results will be used to design a large, definitive trial.

TRIAL REGISTRATION NUMBER

NCT03244514.

Net ultrafiltration rate and its impact on mortality in patients with acute kidney injury receiving continuous renal replacement therapy

Background

Fluid overload, a critical consequence of acute kidney injury (AKI), is associated with worse outcomes. The optimal fluid removal rate per day during continuous renal replacement therapy (CRRT) is unknown. The purpose of this study is to evaluate the impact of the ultrafiltration rate on mortality in critically ill patients with AKI receiving CRRT.

Methods

This was a retrospective cohort study where we reviewed 1398 patients with AKI who received CRRT between December 2006 and November 2015 at the Mayo Clinic, Rochester, MN, USA. The net ultrafiltration rate (UF^NET) was categorized into low- and high-intensity groups (<35 and ≥35 mL/kg/day, respectively). The impact of different UF^NET intensities on 30-day mortality was assessed using logistic regression after adjusting for age, sex, body mass index, fluid balance from intensive care unit (ICU) admission to CRRT initiation, Acute Physiologic Assessment and Chronic Health Evaluation III and sequential organ failure assessment scores, baseline serum creatinine, ICU day at CRRT initiation, Charlson comorbidity index, CRRT duration and need of mechanical ventilation.

Results

The mean ± SD age was 62 ± 15 years, and 827 (59%) were male. There were 696 patients (49.7%) in the low- and 702 (50.2%) in the high-intensity group. Thirty-day mortality was 755 (54%). There were 420 (60%) deaths in the low-, and 335 (48%) in the high-intensity group (P < 0.001). UF^NET ≥35 mL/kg/day remained independently associated with lower 30-day mortality (adjusted odds ratio = 0.47, 95% confidence interval 0.37–0.59; P < 0.001) compared with <35 mL/kg/day.

Conclusions

More intensive fluid removal, UF^NET ≥35 mL/kg/day, among AKI patients receiving CRRT is associated with lower mortality. Future prospective studies are required to confirm this finding.

Global epidemiology and outcomes of acute kidney injury

Acute kidney injury (AKI) is a commonly encountered syndrome associated with various aetiologies and pathophysiological processes leading to decreased kidney function. In addition to retention of waste products, impaired electrolyte homeostasis and altered drug concentrations, AKI induces a generalized inflammatory response that affects distant organs. Full recovery of kidney function is uncommon, which leaves these patients at risk of long-term morbidity and death. Estimates of AKI prevalence range from <1% to 66%. These variations can be explained by not only population differences but also inconsistent use of standardized AKI classification criteria. The aetiology and incidence of AKI also differ between high-income and low-to-middle-income countries. High-income countries show a lower incidence of AKI than do low-to-middle-income countries, where contaminated water and endemic diseases such as malaria contribute to a high burden of AKI. Outcomes of AKI are similar to or more severe than those of patients in high-income countries. In all resource settings, suboptimal early recognition and care of patients with AKI impede their recovery and lead to high mortality, which highlights unmet needs for improved detection and diagnosis of AKI and for efforts to improve care for these patients.

Acute Kidney Injury Following Cardiothoracic Surgery

This article reviews acute kidney injury following cardiothoracic surgery, addressing the full spectrum of the perioperative environment including preoperative, intraoperative, and postoperative factors for acute kidney injury. Topics discussed include pathophysiology, risk prediction scoring, diagnosis, prevention, treatment, and new directions for research.

The future for diagnostic tests of acute kidney injury in critical care: evidence synthesis, care pathway analysis and research prioritisation

BACKGROUND

Acute kidney injury (AKI) is highly prevalent in hospital inpatient populations, leading to significant mortality and morbidity, reduced quality of life and high short- and long-term health-care costs for the NHS. New diagnostic tests may offer an earlier diagnosis or improved care, but evidence of benefit to patients and of value to the NHS is required before national adoption.

OBJECTIVES

To evaluate the potential for AKI in vitro diagnostic tests to enhance the NHS care of patients admitted to the intensive care unit (ICU) and identify an efficient supporting research strategy.

DATA SOURCES

We searched ClinicalTrials.gov, The Cochrane Library databases, Embase, Health Management Information Consortium, International Clinical Trials Registry Platform, MEDLINE, metaRegister of Current Controlled Trials, PubMed and Web of Science databases from their inception dates until September 2014 (review 1), November 2015 (review 2) and July 2015 (economic model). Details of databases used for each review and coverage dates are listed in the main report.

REVIEW METHODS

The AKI-Diagnostics project included horizon scanning, systematic reviewing, meta-analysis of sensitivity and specificity, appraisal of analytical validity, care pathway analysis, model-based lifetime economic evaluation from a UK NHS perspective and value of information (VOI) analysis.

RESULTS

The horizon-scanning search identified 152 potential tests and biomarkers. Three tests, Nephrocheck^® (Astute Medical, Inc., San Diego, CA, USA), NGAL and cystatin C, were subjected to detailed review. The meta-analysis was limited by variable reporting standards, study quality and heterogeneity, but sensitivity was between 0.54 and 0.92 and specificity was between 0.49 and 0.95 depending on the test. A bespoke critical appraisal framework demonstrated that analytical validity was also poorly reported in many instances. In the economic model the incremental cost-effectiveness ratios ranged from £11,476 to £19,324 per quality-adjusted life-year (QALY), with a probability of cost-effectiveness between 48% and 54% when tests were compared with current standard care.

LIMITATIONS

The major limitation in the evidence on tests was the heterogeneity between studies in the definitions of AKI and the timing of testing.

CONCLUSIONS

Diagnostic tests for AKI in the ICU offer the potential to improve patient care and add value to the NHS, but cost-effectiveness remains highly uncertain. Further research should focus on the mechanisms by which a new test might change current care processes in the ICU and the subsequent cost and QALY implications. The VOI analysis suggested that further observational research to better define the prevalence of AKI developing in the ICU would be worthwhile. A formal randomised controlled trial of biomarker use linked to a standardised AKI care pathway is necessary to provide definitive evidence on whether or not adoption of tests by the NHS would be of value.

STUDY REGISTRATION

The systematic review within this study is registered as PROSPERO CRD42014013919.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Kidney Injury Molecule 1 (KIM-1) as an Early Predictor for Acute Kidney Injury in Post-Cardiopulmonary Bypass (CPB) in Open Heart Surgery Patients

INTRODUCTION

Postoperative acute kidney injury is associated with a higher mortality, a more complicated hospital course with longer hospital stay. Urinary kidney injury molecule 1 may play an important role as an early predictor of acute kidney injury post-cardiopulmonary in open heart surgery.

METHODS

We evaluated 45 patients who underwent open heart surgery from January 2016 to June 2016. Both urinary kidney injury molecule 1 and serum creatinine were evaluated before operation and 3hs and 24hs after operation. Acute kidney injury was diagnosed according to Kidney Disease: Improving Global Outcomes, 2012 guidelines.

RESULTS

In this study, 27 patients developed acute kidney injury. The three hour-post-surgery urinary kidney injury molecule 1 was significantly higher in the acute kidney injury group (P<0.015) and, at the same time, we did not find any significant difference in the serum creatinine levels between the two groups.

CONCLUSION

Although serum creatinine is still the gold standard for diagnosis of acute kidney injury searching for other new markers is mandatory. Urinary kidney injury molecule 1 can be used as simple noninvasive and specific biomarker for early diagnosis of acute kidney injury.

Correlation of cardiopulmonary bypass duration with acute renal failure after cardiac surgery

OBJECTIVES

Prolonged cardiopulmonary bypass (CPB) is recognized as a risk factor for acute renal failure (ARF), but the dose effect of time on bypass is unknown. We therefore examined the risk of ARF associated with increasing CPB time stratified by preoperative renal function.

METHODS

A retrospective analysis was performed on 3889 patients undergoing cardiac surgery on CPB without circulatory arrest between 2011 and 2017 excluding those with a diagnosis of dialysis-dependent renal failure and those who had an intra-aortic balloon pump. Postoperative ARF was defined as a 3-fold increase in creatinine level, creatinine level > 4 mg/dL, or requirement for dialysis. A logistic regression model was built to identify predictors of ARF and to determine the probability of ARF.

RESULTS

Postoperative ARF occurred in 72 patients (2%) overall. Of 100 patients with an estimated glomerular filtration rate <30 mL/min/1.73 m², 22% developed ARF, of which 16 required dialysis. Thirty-day mortality was 31% for those with ARF compared with <1% for those without ARF (P < .01). Risk factors for ARF included obesity (odds ratio, 3.03; P < .01), increasing preoperative creatinine level (odds ratio, 4.21; P < .01), CPB time scaled by a factor of 10 minutes (odds ratio, 1.06; P = .04), and postoperative transfusion (odds ratio, 11.94; P < .01). The adjusted probability of ARF as a function of CPB time was determined and stratified by preoperative glomerular filtration rate.

CONCLUSIONS

Increasing CPB duration is associated with postoperative ARF, particularly among those with preoperative renal impairment. For patients with an estimated glomerular filtration rate <30 mL/min/1.73 m² the risk increases exponentially with time.

Safety and efficacy of the perioperative administration of recombinant human brain natriuretic peptide (rhBNP): a systematic review and meta-analysis

Objective

Retrospective studies and a meta-analysis were performed to evaluate the safety and effectiveness of the perioperative administration of recombinant human brain natriuretic peptide (rhBNP) during cardiac surgery under extracorporeal circulation.

Methods

Computerized literature searches were performed in Medline, Embase, The Cochrane Library, CNKI, CBM, and WANFANG to find randomized controlled trials (RCTs) related to the perioperative administration of rhBNP during cardiac surgery starting from the database inception until December 2016. Two researchers independently performed study screening, information extraction, and quality evaluation according to the inclusion/exclusion criteria, and a meta-analysis was performed using RevMan 5.2 software.

Results

A total of 12 studies were analyzed, including 12 RCTs and 727 patients. The meta-analysis results indicated that the perioperative administration of rhBNP could reduce the occurrence rate of postoperative complications, length of intensive care unit (ICU) stay, length of hospital stay, and serum creatinine (Scr) levels, and increase the 24-hour urine volume; however, it did not affect the postoperative mortality rate.

Conclusion

The perioperative administration of rhBNP during cardiac surgery was safe and effective, and could improve the prognosis of the patients.

Postoperative acute kidney injury

Acute kidney injury (AKI) after cardiac surgery is a common and serious complication. Several definitions of AKI have been proposed recently, and include both increases in serum creatinine levels and decreases in urine output as diagnostic criteria. The pathophysiology of postoperative AKI is complex and involves both ischemic injury and systemic inflammation. Identifying risk factors, such as old age, underlying diabetes, heart failure, and obesity, may aid in the application of preventative methods for postoperative AKI. Additionally, recognizing different risks after different types of surgical procedures would be valuable. Novel biomarkers that could detect AKI more precisely at an earlier time point are being investigated. Several new biomarkers have been assessed in large multi-center studies and are believed to accommodate conventional clinical findings in diagnosing postoperative AKI. In high-risk patients, preventative measures, such as the maintenance of adequate hemodynamics and sufficient fluid resuscitation, could lower the incidence of postoperative AKI. Avoiding nephrotoxic agents and optimizing preoperative hemoglobin levels to avoid excessive transfusions would also be beneficial. In situations in which medical management fails to maintain sufficient urine output and acid-base and electrolyte homeostasis, early initiation of renal replacement therapy should be considered.

Prophylactic furosemide infusion decreasing early major postoperative renal dysfunction in on-pump adult cardiac surgery: a randomized clinical trial

INTRODUCTION

Acute renal dysfunction is a common complication of cardiac surgery. Furosemide is used in prevention, or treatment, of acute renal dysfunction. This study was conducted to evaluate the protective effects of intra- and early postoperative furosemide infusion on preventing acute renal dysfunction in elective adult cardiac surgery.

METHODS

Eighty-one patients, candidates of elective cardiac surgery, were enrolled in this study in either the furosemide (n=41) or placebo (n=40) group. Furosemide (2 mg/h) or 0.9% saline was administered and continued up to 12 hours postoperatively. We measured serum creatinine (Scr) at preoperative and on the second and fifth postoperative days. Then calculated estimated glomerular filtration rate (eGFR) at these times. An increase in Scr of >0.5 mg/dL and/or >25%-50%, compared to preoperative values, was considered as acute kidney injury (AKI). In contrast, an increase in Scr by >50% and/or the need for hemodialysis was regarded as acute renal failure (ARF). At the end we compared the AKI or ARF incidence between the two groups.

RESULTS

On the second and fifth postoperative days, Scr was lower, and the eGFR was higher in the furosemide group. AKI incidence was similar in the two groups (11 vs 12 cases; P-value 0.622); however, ARF rate was lower in furosemide group (1 vs 6 cases; P-value 0.044). During the study period, Scr was more stable in the furosemide group, however in the placebo group, Scr initially increased and then decreased to its preoperative value after a few days.

CONCLUSION

This study showed that intra- and early postoperative furosemide infusion has a renal protective effect in adult cardiac surgery with cardiopulmonary bypass. Although this protective effect cannot be discovered in mild renal dysfunctions, it apparently reduces the rate of the more severe renal dysfunctions. A more multidisciplinary strategy may be needed in reducing the milder renal damage.

Renal Insufficiency After Cardiac Surgery

The new millennium ushered in a number of changes in cardiac surgery. Off-pump coronary artery bypass surgery became technically easier so that multivessel surgery became less of a challenge and cardiologists were supplied with new catheters that accessed lesions that were previously thought of as being unapproachable. New drugs were introduced that made the management of heart failure patients feasible on an outpatient basis, and new devices extend the bridging period to transplantation. However, these advances have not necessarily been attended by significant improvements in outcome, possibly because the less challengng a procedure becomes, the sicker the patients that can be managed. This observation is particularly true with the incidence and outcome of renal failure after cardiac surgery. Bypass factors have been manipulated without much effect, and the traditional drugs that were found to increase renal blood flow in animal experiments did not translate into clinical improvement in renal outcome. Recent research has given us insight into the pathophysiology of ischemic acute renal failure, and it has been found that the paradigm was not as simple as previously thought, possibly accounting for the failure of the more traditional renal drugs (dopamine, mannitol and diuretics). However, these new insights open up the possibility of novel targets for renal protection and repair.

Intensive Care Unit Stay of More than 14 Days after Cardiac Surgery is Associated with Non-cardiac Organ Failure

Some studies have shown an association between a prolonged intensive care unit (ICU) stay and risk factors such as mediastinal re-exploration, advanced age, low ejection fraction, lung disease and organ failure. The aim of this retrospective study was first to evaluate peri-operative risk factors ( n = 2683) and secondly to evaluate long-term survival ( n = 2563) in cardiac surgery patients with an ICU stay > 14 days. Long-term survival was assessed in an observational 3-year follow-up study. An ICU stay of > 14 days was associated independently with respiratory failure and dialysis-dependent acute renal failure, and with a significantly lower survival rate. Since an ICU stay is associated with a higher hospital and long-term mortality, measures should be taken throughout the entire hospital stay to identify and reduce the risk of organ failure.

Prediction and Prevention of Acute Kidney Injury after Cardiac Surgery

The incidence of acute kidney injury after cardiac surgery (CS-AKI) ranges from 33% to 94% and is associated with a high incidence of morbidity and mortality. The etiology is suggested to be multifactorial and related to almost all aspects of perioperative management. Numerous studies have reported the risk factors and risk scores and novel biomarkers of AKI have been investigated to facilitate the subclinical diagnosis of AKI. Based on the known independent risk factors, many preventive interventions to reduce the risk of CS-AKI have been tested. However, any single preventive intervention did not show a definite and persistent benefit to reduce the incidence of CS-AKI. Goal-directed therapy has been considered to be a preventive strategy with a substantial level of efficacy. Many pharmacologic agents were tested for any benefit to treat or prevent CS-AKI but the results were conflicting and evidences are still lacking. The present review will summarize the current updated evidences about the risk factors and preventive strategies for CS-AKI.

Effect of utilization of veno-venous bypass vs. cardiopulmonary bypass on complications for high level inferior vena cava tumor thrombectomy and concomitant radical nephrectomy

Purpose:

To determine if patients with renal cell carcinoma (RCC) with levels III and IV tumor thrombi are receive any reduction in complication rate utilizing veno-venous bypass (VVB) over cardiopulmonary bypass (CPB) for high level (III/IV) inferior vena cava (IVC) tumor thrombectomy and concomitant radical nephrectomy.

Materials and Methods:

From May 1990 to August 2011, we reviewed 21 patients that had been treated for RCC with radical nephrectomy and concomitant IVC thrombectomy employing either CPB (n =16) or VVB (n=5). We retrospectively reviewed our study population for complication rates and perioperative characteristics.

Results:

Our results are reported using the validated Dindo-Clavien Classification system comparing the VVB and CPB cohorts. No significant difference was noted in minor complication rate (60.0% versus 68.7%, P=1.0), major complication rate (40.0% versus 31.3%, P=1.0), or overall complication rate (60.0% versus 62.5%, P=1.0) comparing VVB versus CPB. We also demonstrated a trend towards decreased time on bypass (P=0.09) in the VVB cohort.

Conclusion:

The use of VVB over CPB provides no decrease in minor, major, or overall complication rate. The use of VVB however, can be employed on an individualized basis with final decision on vascular bypass selection left to the discretion of the surgeon based on specifics of the individual case.

Effect of remote ischemic preconditioning on postoperative acute kidney injury among patients undergoing cardiac and vascular interventions: a meta-analysis

It is currently controversial whether remote ischemic preconditioning (RIPC) reduces the incidence of acute kidney injury (AKI) in patients undergoing cardiovascular interventions. The main objective of this meta-analysis was to investigate whether RIPC provides renal protection for patients undergoing cardiac or vascular surgery. We searched the PubMed database (1966-Oct 2015), Embase database (1966-Oct 2015), Google Scholar, Cochrane Library, ClinicalTrials Database and Open Grey. Then we conducted a meta-analysis of the randomized controlled trials that met the inclusion criteria of our study. The interventions included use of an inflatable tourniquet around the limbs or cross-clamping of the iliac arteries before surgery (RIPC groups) and general cardiovascular intervention (control groups). The main outcomes examined included the incidence of AKI; changes in acute kidney injury biomarkers; and use of renal replacement therapy. Other outcomes examined included in-hospital mortality and the lengths of hospital stay and intensive care unit (ICU) stay. Finally, we screened 26 eligible studies containing 6699 patients who underwent cardiac or vascular interventions with RIPC (n = 3343) or without RIPC (n = 3356). The AKI incidence was decreased in the RIPC group as was the length of ICU stay. There were no differences in the changes in AKI biomarkers, use of renal replacement therapy or in-hospital mortality between the two groups. Remote ischemic preconditioning may decrease the occurrence of AKI in cardiovascular surgery patients. Since studies included have a significant heterogeneity, meta-analyses using a stricter inclusion criteria are needed to clarify the renoprotection effect of RIPC.

Preoperative Low Serum Bicarbonate Levels Predict Acute Kidney Injury After Cardiac Surgery

Acute kidney injury (AKI) after cardiac surgery is a common and serious complication. Although lower than normal serum bicarbonate levels are known to be associated with consecutive renal function deterioration in patients with chronic kidney injury, it is not well-known whether preoperative low serum bicarbonate levels are associated with the development of AKI in patients who undergo cardiac surgery. Therefore, the clinical implication of preoperative serum bicarbonate levels on AKI occurrence after cardiac surgery was investigated. Patients who underwent coronary artery bypass or valve surgery at Yonsei University Health System from January 2013 to December 2014 were enrolled. The patients were divided into 3 groups based on preoperative serum bicarbonate levels, which represented group 1 (below normal levels) <23 mEq/L; group 2 (normal levels) 23 to 24 mEq/L; and group 3 (elevated levels) >24 mEq/L. The primary outcome was the predicated incidence of AKI 48 hours after cardiac surgery. AKI was defined according to Acute Kidney Injury Network criteria. Among 875 patients, 228 (26.1%) developed AKI within 48 hours after cardiac surgery. The incidence of AKI was higher in group 1 (40.9%) than in group 2 (26.5%) and group 3 (19.5%) (P < 0.001). In addition, the duration of postoperative stay in a hospital intensive care unit (ICU) was longer for AKI patients and for those in the low-preoperative-serum-bicarbonate-level groups. A multivariate logistic regression analysis showed that low preoperative serum bicarbonate levels were significantly associated with AKI even after adjustment for age, sex, hypertension, diabetes mellitus, operation type, preoperative hemoglobin, and estimated glomerular filtration rate. In conclusion, low serum bicarbonate levels were associated with higher incidence of AKI and prolonged ICU stay. Further studies are needed to clarify whether strict correction of bicarbonate levels close to normal limits may have a protective role in preventing further AKI development.

The effect of pulsatile cardiopulmonary bypass on the need for haemofiltration in patients with renal dysfunction undergoing cardiac surgery

OBJECTIVES

The aim of our study was to investigate the effects of pulsatile cardiopulmonary bypass (CPB) on renal function and the need for haemofiltration in patients with preoperative renal impairment undergoing cardiac surgery.

METHODS

Clinical data were collected prospectively for patients undergoing cardiac surgery with pulsatile CPB (Group A, n=66) and compared to matched patients with standard non-pulsatile CPB (Group B, n=66). Patients included in the study had mild renal impairment and at least moderate risk from surgery as defined by logistic EuroSCORE. Emergency operations were excluded.

RESULTS

Patients in Groups A and B had similar age (71 ± 10 versus 70 ± 10 years), sex distribution, mean preoperative renal function (creatinine clearance 63.9 ± 28 versus 67.7 ± 27.3 ml/min) and overall risk profile as predicted by the logistic EuroSCORE (8 ± 8.3 versus 11.05±13.3, p=0.122). Intraoperative variables were comparable with respect to bypass and cross-clamp times (96 ± 37 minutes and 64 ± 28 minutes versus 103 ± 40 minutes and 70 ± 33 minutes in Groups A and B, respectively). A smaller proportion of patients in Group A (4.5% versus 15%, p=0.076) required haemofiltration in the postoperative period. Postoperative mortality was low in both groups (Group A 1.54% versus Group B 3.03%, p=1.00).

CONCLUSION

Within the limitations imposed by retrospective analyses, our study demonstrates that pulsatile CPB may confer a reno-protective effect in higher-risk patients with pre-existing mild renal dysfunction undergoing cardiac surgery.

Association of cardiac biomarkers with acute kidney injury after cardiac surgery: A multicenter cohort study

OBJECTIVE

Acute kidney injury is common after cardiac surgery and associated with postoperative mortality. Perioperative cardiac biomarkers may predict acute kidney injury and mortality. We evaluated whether cardiac biomarkers were associated with severe acute kidney injury, defined as a doubling in serum creatinine or requiring renal replacement therapy during hospital stay after surgery, and mortality.

METHODS

In a prospective multicenter cohort of adults undergoing cardiac surgery, we measured the following biomarkers in preoperative and postoperative banked plasma: high-sensitivity troponin T, cardiac troponin I, creatine kinase-MB, and N-terminal prohormone of brain natriuretic peptide.

RESULTS

In the patients who were discharged alive, severe acute kidney injury occurred in 37 of 960 (3.9%), and 43 of 960 (4.5%) died within 1 year of follow-up. N-terminal prohormone of brain natriuretic peptide was the only preoperative biomarker that was independently associated with severe acute kidney injury (with log transformation, adjusted odds ratio, 1.4; 95% confidence interval, 1.0-1.9). Biomarkers measured within 6 hours of surgery (day 1) were all associated with severe acute kidney injury. Preoperative N-terminal prohormone of brain natriuretic peptide was also independently associated with 1-year mortality (with log transformation, adjusted odds ratio, 1.7; 95% confidence interval, 1.2-2.2). Patients in the highest tertile for N-terminal prohormone of brain natriuretic peptide preoperatively (>1006.4 ng/L) had marked increases in their risk for 1-year mortality (adjusted odds ratio, 27.2; 95% confidence interval, 3.5-213.5). Day 1 N-terminal prohormone of brain natriuretic peptide was associated with mortality independently of change in serum creatinine from preoperative baseline.

CONCLUSIONS

Of the studied biomarkers, N-terminal prohormone of brain natriuretic peptide was the only preoperative biomarker independently associated with severe acute kidney injury and mortality. Early increases in postoperative cardiac biomarkers were associated with severe acute kidney injury after cardiac surgery. Future research should focus on whether interventions that lower N-terminal prohormone of brain natriuretic peptide can affect postoperative outcomes.

Incidence and impact of acute kidney injury in patients with acute coronary syndromes treated with coronary artery bypass grafting: Insights from the Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) and Acute Catheterization and Urgent Intervention Triage Strategy (ACUITY) trials

BACKGROUND

Acute kidney injury (AKI) is a well-recognized predictor of morbidity and mortality after percutaneous coronary intervention. However, the impact of AKI on the outcome of patients with acute coronary syndromes (ACS) in relation to coronary artery bypass grafting (CABG) has not been established.

METHODS

Of the 17,421 patients who presented with non-ST-segment elevation ACS or ST-segment elevation myocardial infarction enrolled in the ACUITY and HORIZONS-AMI trials, 1,406 (8.0%) underwent CABG as principal treatment after coronary angiography. End points were measured at 1 month and 1 year and included death, myocardial infarction, and ischemia-driven target vessel revascularization. Acute kidney injury was defined as a rise in creatinine of ≥ 0.5 mg/dL, or > 25%, from baseline at initial angiography.

RESULTS

Acute kidney injury occurred during hospital admission in 449 (31.9%) of the 1,406 patients treated with CABG. One-month and 1-year mortality was 6.7% vs 2.2% (P < .0001) and 10.4% vs 4.3% (P < .0001) for patients with vs without AKI, respectively. Analogously, the 1-month and 1-year incidence of composite major adverse cardiac events (MACEs; death, MI, or target vessel revascularization) was 17.6% vs 12.4% (P = .003) and 22.0% vs 15.3% (P = .002) for patients with vs without AKI, respectively. After adjustment for age, sex, race, diabetes, hypertension, and baseline creatinine clearance, AKI was an independent predictor of mortality (overall and cardiac-related) and MACE at both 1 month and 1 year in patients treated with CABG.

CONCLUSIONS

Acute kidney injury occurred in approximately 1 of every 3 patients with ACS treated with CABG and is a powerful independent predictor of death and MACE. These data highlight the need for AKI prevention strategies in patients undergoing CABG.

Primary Cardiac Allograft Dysfunction-Validation of a Clinical Definition

Background

Heart transplantation is an established treatment for advanced heart failure. Primary allograft dysfunction (PGD) is reported in up to 40% of transplants and is associated with a poor outcome.

Methods

As part of Heart Evaluation and Retrieval for Transplantation study, an investigation of the assessment of donor hearts for transplantation, we proposed a clinical definition for cardiac PGD comprising severely impaired systolic function affecting one or both ventricles accompanied by hypotension, low cardiac output, and high filling pressures occurring in the first 72 hours (in the absence of hyper acute rejection and technical surgical factors, such as cardiac tamponade). Here, we examine the prospective application of this definition to 290 heart transplants. We compared the clinical outcome of PGD and non-PGD cases.

Results

Ninety-four of 290 transplants developed PGD (32.4%). Inotrope use (score) was higher in the PGD group at 24, 48, and 72 hours after transplantation (P < 0.01). In the PGD group, there was a greater requirement for, intra-aortic balloon pump (50% vs 15%, P < 0.01), mechanical support (27% vs 0%, P < 0.01), and renal replacement therapy (61% vs 26%, P < 0.01). Intensive care stay was longer for recipients with PGD (median 14 vs 5 days, P < 0.01) and early mortality was higher (37% vs 4% at 30 days, 42% vs 8% at 1 year, P < 0.01).

Conclusions

In conclusion, our definition of PGD could be applied in a national multicenter study, and the cases it defined had more frequent complications and higher mortality.

Classification of primary cardiac allograft dysfunction into three grades has been shown to be predictive of 30-day mortality in a prospective study of 290 heart transplants. This demonstrated that the classification system would be applicable for use in multicenter studies.

Preoperative factors associated with postoperative requirements of renal replacement therapy following cardiac surgery

Renal dysfunction is a major adverse event after cardiovascular surgery. Therefore, the preoperative prediction of which patients will require renal replacement therapy (RRT) after cardiac surgery is an important issue. In the present study, 1,822 consecutive patients who underwent cardiovascular surgery from 2008 and 2013 at a single institution were reviewed. Patients who were already receiving long-term hemodialysis before surgery (n = 134) were excluded. The remaining 1,688 patients were separated into 2 groups: those requiring postoperative RRT and those without RRT requirement. A total of 128 patients (7.6%) required RRT. Patients requiring RRT had greater perioperative blood loss, longer intubation time, and longer hospital stays (p <0.0001 for all). Multivariate analysis revealed that cardiopulmonary bypass use, preoperative body surface area, the left ventricular ejection fraction, serum albumin, and creatinine were independent risk factors for postoperative RRT (odds ratios 2.435, 0.204, 0.976, 0.556, and 5.394, 95% confidence intervals 1.471 to 4.140, 0.054 to 0.841, 0.962 to 1.025, 0.363 to 0.860, and 3.671 to 8.223, respectively, p <0.05 for all). A subgroup of patients with relatively preserved renal function before surgery (creatinine <1.12 mg/dl, a cut-off value for RRT requirement obtained from receiver-operating characteristic curve analysis [area under the curve 0.74748, sensitivity 60.2%, specificity 85.0%]) showed that preoperative serum albumin concentration was most significantly associated with postoperative RRT requirement (odds ratio 0.048, 95% confidence interval 0.023 to 0.095, p <0.0001). In conclusion, cardiopulmonary bypass use, preoperative renal impairment as reflected by elevated creatinine level, small body size, a low left ventricular ejection fraction, and hypoalbuminemia were associated with a requirement for postoperative RRT. In patients with preserved renal function, hypoalbuminemia was most significantly related to requirement for RRT.

Inclusion of 'ICU-Day' in a Logistic Scoring System Improves Mortality Prediction in Cardiac Surgery

Background

Prolonged intensive care unit (ICU) stay is a predictor of mortality. The length of ICU stay has never been considered as a variable in an additive scoring system. How could this variable be integrated into a scoring system? Does this integration improve mortality prediction?

Material/Methods

The ‘modified CArdiac SUrgery Score’ (CASUS) was generated by implementing the length of stay as a new variable to the ‘additive CASUS’. The ‘logistic CASUS’ already considers this variable. We defined outcome as ICU mortality and statistically compared the three CASUS models. Discrimination, comparison of receiver operating characteristic curves (DeLong’s method), and calibration (observed/expected ratio) were analyzed on days 1–13.

Results

Between 2007 and 2010, we included 5207 cardiac surgery patients in this prospective study. The mean age was 67.2±10.9 years. The mean length of ICU stay was 4.6±7.0 days and ICU mortality was 5.9%. All scores had good discrimination, with a mean area under the curve of 0.883 for the additive and modified, and 0.895 for the ‘logistic CASUS’. DeLong analysis showed superiority in favor of the logistic model as from day 5. The calibration of the logistic model was good. We identified overestimation (days 1–5) and accurate (days 6–9) calibration for the additive and ‘modified CASUS’. The ‘modified CASUS’ remained accurate but the ‘additive CASUS’ tended to underestimate the risk of mortality (days 10–13).

Conclusions

The integration of length of ICU stay as a variable improves mortality prediction significantly. An ‘ICU-day’ variable should be included into a logistic but not an additive model.

Severe acute kidney injury following cardiac surgery: short-term outcomes in patients undergoing continuous renal replacement therapy (CRRT)

BACKGROUND

Acute kidney injury (AKI) represents a major complication of cardiac surgery. Our aim was to evaluate, in patients undergoing continuous renal replacement therapy (CRRT) for cardiac surgery-associated AKI (CS-AKI), prognostic factors related to in-hospital survival and renal function recovery to independence from RRT.

METHODS

We conducted a retrospective analysis in patients with severe CS-AKI who underwent CRRT for at least 48 h. The sequential organ failure assessment (SOFA) score was calculated on a daily basis to evaluate illness severity throughout the intensive care unit (ICU) stay.

RESULTS

In 264 patients (age 66.4 ± 11.7 years, 192 males), 30-day survival was 57.6 % while survival to discharge from the hospital was 40.5 %. Renal function recovery occurred in 96.3 % of survivors and in 13.4 % of non-survivors (p < 0.001). Multivariate analysis selected advancing age, oliguria, sepsis and the highest level of SOFA score within the first week of CRRT (SOFA-max) as independent prognostic factors for failure to recover renal function. Female gender was associated with a higher probability of survival, while higher serum creatinine at the start of CRRT, oliguria, sepsis and SOFA-max were independently associated with mortality. The subgroup of patients with a day-1 SOFA score above the median (≥10) showed a lower probability of survival and a lower cumulative incidence of renal function recovery.

CONCLUSIONS

In a selected population of patients with severe CS-AKI requiring RRT, short-term outcomes appear strongly associated with the worst grade of illness severity during the first week of CRRT, thus reflecting the sequential occurrence of additional major complications during ICU stay. Renal function recovery and in-hospital survival appear mutually linked, sharing oliguria, sepsis and SOFA score as the main determinants of both outcomes.

HMG CoA reductase inhibitors (statins) for preventing acute kidney injury after surgical procedures requiring cardiac bypass

BACKGROUND

Acute kidney injury (AKI) is common in patients undergoing cardiac surgery among whom it is associated with poor outcomes, prolonged hospital stays and increased mortality. Statin drugs can produce more than one effect independent of their lipid lowering effect, and may improve kidney injury through inhibition of postoperative inflammatory responses.

OBJECTIVES

This review aimed to look at the evidence supporting the benefits of perioperative statins for AKI prevention in hospitalised adults after surgery who require cardiac bypass. The main objectives were to 1) determine whether use of statins was associated with preventing AKI development; 2) determine whether use of statins was associated with reductions in in-hospital mortality; 3) determine whether use of statins was associated with reduced need for RRT; and 4) determine any adverse effects associated with the use of statins.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 13 January 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that compared administration of statin therapy with placebo or standard clinical care in adult patients undergoing surgery requiring cardiopulmonary bypass and reporting AKI, serum creatinine (SCr) or need for renal replacement therapy (RRT) as an outcome were eligible for inclusion. All forms and dosages of statins in conjunction with any duration of pre-operative therapy were considered for inclusion in this review.

DATA COLLECTION AND ANALYSIS

All authors extracted data independently and assessments were cross-checked by a second author. Likewise, assessment of study risk of bias was initially conducted by one author and then by a second author to ensure accuracy. Disagreements were arbitrated among authors until consensus was reached. Authors from two of the included studies provided additional data surrounding post-operative SCr as well as need for RRT. Meta-analyses were used to assess the outcomes of AKI, SCr and mortality rate. Data for the outcomes of RRT and adverse effects were not pooled. Adverse effects taken into account were those reported by the authors of included studies.

MAIN RESULTS

We included seven studies (662 participants) in this review. All except one study was assessed as being at high risk of bias. Three studies assessed atorvastatin, three assessed simvastatin and one investigated rosuvastatin. All studies collected data during the immediate perioperative period only; data collection to hospital discharge and postoperative biochemical data collection ranged from 24 hours to 7 days. Overall, pre-operative statin treatment was not associated with a reduction in postoperative AKI, need for RRT, or mortality. Only two studies (195 participants) reported postoperative SCr level. In those studies, patients allocated to receive statins had lower postoperative SCr concentrations compared with those allocated to no drug treatment/placebo (MD 21.2 µmol/L, 95% CI -31.1 to -11.1). Adverse effects were adequately reported in only one study; no difference was found between the statin group compared to placebo.

AUTHORS' CONCLUSIONS

Analysis of currently available data did not suggest that preoperative statin use is associated with decreased incidence of AKI in adults after surgery who required cardiac bypass. Although a significant reduction in SCr was seen postoperatively in people treated with statins, this result was driven by results from a single study, where SCr was considered as a secondary outcome. The results of the meta-analysis should be interpreted with caution; few studies were included in subgroup analyses, and significant differences in methodology exist among the included studies. Large high quality RCTs are required to establish the safety and efficacy of statins to prevent AKI after cardiac surgery.

Acute kidney injury after aortic valve replacement: incidence, risk factors and outcomes

The occurrence of acute kidney injury (AKI) following aortic valve replacement (AVR) has very serious clinical implications and has therefore been the focus of several studies. The authors report the results of previous studies evaluating both transcatheter AVR (TAVR) and indirectly surgical AVR (SAVR) through looking at cardiopulmonary bypass (CPB) cardiac surgeries, and identify the incidence, predictors and outcomes of AKI following AVR. In most studies, AKI was defined using the Risk, Injury, Failure, Loss and End Stage, Valve Academic Research Consortium (modified Risk, Injury, Failure, Loss and End Stage) or Valve Academic Research Consortium-2 (Acute Kidney Injury Network) AKI classification criteria. Twelve studies including more than 90,000 patients undergoing cardiac surgery on CPB were considered as well as 26 studies with more than 6000 patients undergoing TAVR. Depending on the definition used, AKI occurred in 3.4-43% of SAVR cases with up to 2.5% requiring dialysis, and in 3.4-57% of TAVR cases. Factors identified as independent predictors of AKI were: baseline kidney failure, EUROSCORE, diabetes mellitus, hypertension, chronic obstructive pulmonary disease, anemia, peripheral vascular disease, heart failure, surgical priority, CPB time, reoperation, use of intra-aortic balloon pump, need for re-exploration, contrast agent volume, transapical access, blood transfusion, postoperative thrombocytopenia, postoperative leukocytosis as well as demographic variables such as age and female gender. The 30-day mortality rate for patients with AKI following SAVR ranged from 5.5 to 46% and was 3- to 16-times higher than in those without AKI. Similarly, patients who developed AKI after TAVR had a mortality rate of 7.8-29%, which was two- to eight-times higher than those who did not suffer from AKI. AKI confers up to a fourfold increase in 1-year mortality. Finally, hospital length of stay was significantly increased in patients with AKI in both SAVR and TAVR groups, with increases up to 3- and 2.5-times, respectively.

Post cardiac surgery acute kidney injury: a woebegone status rejuvenated by the novel biomarkers

Background:

Acute kidney injury (AKI) is common after cardiac surgery, the incidence varying between 7.7% and 28.1%. It significantly increases morbidity and mortality. Creatinine considerably delays the diagnosis with its own attended demerits. Novel urinary biomarkers are emerging which help in rapid diagnosis thus reducing the morbidity and mortality. Biomarkers of our study were neutrophil gelatinase-associated lipocalin (NGAL) and Interleukin-18 (IL-18).

Objectives:

To find out the incidence of AKI in post-cardiac surgery patients in our hospital, the ability of the two biomarkers in early diagnosis in predicting the severity of AKI based on RIFLE’s criteria and their ability to discriminate pre-renal from intrinsic AKI.

Patients and Methods:

One-hundred patients who underwent cardiac surgery were selected. Midstream urine samples were collected at 3 time intervals (baseline before surgery, 24 hours and 7 days after surgery). Biomarkers were measured by ELISA using BIORAD processors. Fractional excretion of sodium and urea were used to discriminate pre-renal from intrinsic AKI.

Results:

Out of 100 patients, 31 had AKI, 11 being pre-renal and 20 intrinsic AKI. Four patients required renal replacement therapy (12.9% among AKI cases and 4% in the overall study cohort). Four among 31 expired in intensive care unit. Identifiable risk factors for AKI included insulin requiring diabetes mellitus, chronic obstructive pulmonary disease, increased cardio-pulmonary bypass time, combined valvular surgery and coronary artery bypass grafting, employment of intra-aortic balloon counter pulsation, left main coronary artery occlusion and an ejection fraction of < 40%. NGAL was extremely sensitive (area under curve-0.96) in detecting intrinsic AKI at 24 hours followed by IL-18 ratio with an area under curve of 0.89. Creatinine at 24 hours was able to detect only 31.6% of intrinsic AKI. None of the pre-renal cases showed rise in the urinary biomarker levels. Patients with higher stages of AKI had higher levels of both biomarkers than those at lower stages.

Conclusions:

NGAL and IL-18 obviated the disadvantages of creatinine. They were efficient in early detection of AKI, in differentiating pre-renal from intrinsic AKI and in predicting the severity of AKI reliably in post-cardiac surgery patients.

Prognostic relevance of early AKI according to pRIFLE criteria in children undergoing cardiac surgery

BACKGROUND

Acute renal injury increases risk of death after cardiac surgery. The objective of the study was to evaluate the ability of the pediatric Risk, Injury, Failure, Loss, End-Stage Renal Disease (pRIFLE) criteria to characterize the development of postoperative renal damage in children after cardiopulmonary bypass (CPB) and to evaluate the relationship between the severity of kidney injury and mortality, pediatric intensive care unit (PICU) length of stay, and the duration of mechanical ventilation (MV).

METHODS

In this retrospective study including children undergoing CPB surgery during a 3-year period in the PICU of a tertiary hospital, demographic, clinical, surgery-related, and postoperative clinical data were collected. Kidney damage was assessed with pRIFLE criteria.

RESULTS

Four hundred and nine patients were included. Early acute kidney injury (AKI) was found in 82 patients (achieving categories Risk 44; Injury 16; Failure 22). Early AKI was associated with younger age (P = 0.010), longer CPB, deep hypothermic circulatory arrest (DHCA) use, ICU stay >12 days, MV >4 days, and death (P < 0.001). Controlling the effect of age, CPB, DHCA use, previous cardiac surgeries, and Risk Adjustment in Congenital Heart Surgery Surgical Severity Score (RACHS-1), early AKI development proved to predict ICU stay >12 days [odds ratio (OR) 3.5; 95% confidence interval (CI) 1.9-6.5, P < 0.001)] and need of MV >4 days (OR 5.1; 95% CI 2.6-10.2, P < 0.001).

CONCLUSIONS

Early AKI when evaluated with the pRIFLE criteria can predict prolonged ICU stay, need of prolonged MV, and mortality.

Effect of early and intensive continuous venovenous hemofiltration on patients with cardiogenic shock and acute kidney injury after cardiac surgery

OBJECTIVE

Continuous renal replacement therapy (CRRT) is currently the mainstay renal support for critically ill patients. However, the optimal intensity of CRRT remains debated owing to the heterogeneity of the study populations and CRRT techniques across centers. The present study investigated the beneficial effects of early and intensive continuous venovenous hemofiltration (CVVH) on patients with shock after cardiotomy.

METHODS

Patients who had received CRRT for cardiogenic shock and acute kidney injury after cardiac surgery from January 2003 to December 2007 were retrospectively recruited. They were divided into 2 groups according to the delivered dosage of hemofiltration.

RESULTS

The mean duration between intensive care unit admission and initiation of CVVH was 1.4±0.8 days. The all-cause mortality by day 30 was 73.3% and 45.4% in the low- and high-dose groups, respectively (P=.002). The corresponding in-hospital mortality rate was 82.2% and 61.8% (P=.02). No significant difference was seen in the renal recovery of the survivors between the 2 groups.

CONCLUSIONS

In patients developing postoperative cardiogenic shock and acute kidney injury after cardiac surgery, an early higher CVVH dose was associated with better in-hospital and long-term survival. Moreover, the beneficial effect of intensive treatment might be more critical in the early perioperative period.

Continuous renal replacement therapy in children after cardiac surgery

OBJECTIVE

The objective was to study the clinical course of children requiring continuous renal replacement therapy (CRRT) after cardiac surgery and to analyze the factors associated with mortality.

METHODS

A prospective observational study was performed that included all children requiring CRRT after cardiac surgery, comparing these patients with other critically ill children requiring CRRT. Univariate and multivariate analyses were performed to determine the influence of each factor on mortality.

RESULTS

Eighty-one (4.9%) of 1650 children undergoing cardiac surgery required CRRT; 65 of them (80.2%) presented multiorgan failure. Children starting CRRT after cardiac surgery had lower mean arterial pressure and lower urea and creatinine levels, and were more likely to require mechanical ventilation than other children on CRRT. The incidence of complications was similar. Cardiac surgery increased the probability of requiring CRRT for more than 14 days. Mortality was 43% in children receiving CRRT after cardiac surgery and 29% in other children (P = .05). Factors associated with mortality in the univariate analysis were age less than 12 months, weight less than 10 kg, higher Pediatric Risk of Mortality Score, hypotension, lower urea and creatinine on starting CRRT, and use of hemofiltration. In the multivariate analysis, the only factor associated with mortality was hypotension on starting CRRT (hazard ratio, 4.01; 95% confidence interval, 1.2-13.4; P = .024).

CONCLUSIONS

Although only a small percentage of children undergoing cardiac surgery required CRRT, mortality in these patients was high. Hypotension at the time of starting the technique was the only factor associated with a higher mortality.

Contrast-enhanced ultrasound to evaluate changes in renal cortical perfusion around cardiac surgery: a pilot study

Introduction

Contrast-enhanced ultrasound (CEUS) is a new technique that might enable portable and non-invasive organ perfusion quantification at the bedside. However, it has not yet been tested in critically ill patients. We sought to establish CEUS's feasibility, safety, reproducibility and potential diagnostic value in the assessment of renal cortical perfusion in the peri-operative period in cardiac surgery patients.

Methods

We recruited twelve patients deemed at risk of acute kidney injury (AKI) planned for elective cardiac surgery. We performed renal CEUS with destruction-replenishment sequences before the operation, on ICU arrival and the day following the admission. Enhancement was obtained with Sonovue^® (Bracco, Milano, Italy) at an infusion rate of 1 ml/min. We collected hemodynamic parameters before, during and after contrast agent infusion. At each study time, we obtained five video sequences, which were analysed using dedicated software by two independent radiologists blinded to patient and time. The main output was a perfusion index (PI), corresponding to the ratio of relative blood volume (RBV) over mean transit time (mTT).

Results

All 36 renal CEUS studies, including 24 in the immediate post-operative period could be performed and were well tolerated. Correlation between readers for PI was excellent (R² = 0.96, P < 0.0001). Compared with baseline, there was no overall difference in median PI's on ICU admission. However, the day after surgery, median PI's had decreased by 50% (P < 0.01) (22% decrease in RBV (P = 0.09); 48% increase in mTT (P = 0.04), both suggestive of decreased perfusion). These differences persisted after correction for haemoglobin; vasopressors use and mean arterial pressure. Four patients developed AKI in the post-operative period.

Conclusions

CEUS appears feasible and well-tolerated in patients undergoing cardiac surgery even immediately after ICU admission. CEUS derived-parameters suggest a decrease in renal perfusion occurring within 24 hours of surgery.

Acute renal dysfunction: time from coronary angiography to cardiac surgery

Background

The incidence of acute renal dysfunction has not changed much over the years, despite improvements in perioperative care. Our objectives were to evaluate the impact of timing of cardiac surgery after coronary angiography on acute renal dysfunction, to identify risk factors associated with development of acute renal dysfunction, and to measure the association between acute renal dysfunction and mortality.

Patients and methods

The patients were divided into 3 groups: group A (cardiac surgery 0–3 days after angiography), group B (surgery 4–6 days after angiography), and group C (surgery > 6 days after angiography). Endpoints were acute renal dysfunction, defined as serum creatinine > 25% of baseline on the 3rd postoperative day, and mortality.

Results

In 749 patients, the incidence of acute renal dysfunction was 15%; 5% required dialysis. Hypertension, congestive heart failure, chronic obstructive pulmonary disease, ejection fraction < 40%, prolonged cardiopulmonary bypass time, intraaortic balloon pump use, and urgent surgery were risk factors for acute renal dysfunction after cardiac surgery. Patients in group C had a lower risk of acute renal dysfunction.

Conclusion

Acute renal dysfunction has a definite relationship with the time period between angiography and cardiac surgery. The causative factors for this condition are multiple and also show a consistent association with mortality.