The KDIGO acute kidney injury guidelines for cardiac surgery patients in critical care: a validation study

Effect of Delayed Remote Ischemic Preconditioning on Acute Kidney Injury and Outcomes in Patients Undergoing Cardiac Surgery: A Randomized Clinical Trial

BACKGROUND

Remote ischemic preconditioning (RIPC) has 2 time windows for organ protection: acute and delayed. Previous studies have mainly focused on the organoprotective effects of acute RIPC. We aimed to determine whether delayed RIPC can reduce the occurrence of acute kidney injury (AKI) and postoperative complications in patients undergoing cardiac surgery.

METHODS

This prospective, single-center, double-blind, randomized controlled trial involved 509 patients at high risk for AKI who were scheduled for elective cardiac surgery requiring cardiopulmonary bypass. Patients were randomized to receive RIPC (4 cycles of 5-minute inflation and 5-minute deflation on 1 upper arm with a blood pressure cuff) 24 hours before surgery or a sham condition (control group) that was induced by 4 cycles of 5-minute inflation to a pressure of 20 mm Hg followed by 5-minute cuff deflation. The primary end point was the incidence of AKI within the prior 7 days after cardiac surgery. The secondary end points included renal replacement therapy during hospitalization, change in urinary biomarkers of AKI and markers of myocardial injury, duration of intensive care unit stay and mechanical ventilation, and occurrence of nonfatal myocardial infarction, stroke, and all-cause mortality by day 90.

RESULTS

A total of 509 patients (mean age, 65.2±8.2 years; 348 men [68.4%]) were randomly assigned to the RIPC group (n=254) or control group (n=255). AKI was significantly reduced in the RIPC group compared with the control group (69/254 [27.2%] versus 90/255 [35.3%]; odds ratio, 0.68 [95% CI, 0.47-1.00]; P=0.048). There were no significant between-group differences in the secondary end points of perioperative myocardial injury (assessed by the concentrations of cardiac troponin T, creatine kinase myocardial isoenzyme, and NT-proBNP [N-terminal pro-brain natriuretic peptide]), duration of stay in the intensive care unit and hospital, and occurrence of nonfatal myocardial infarction, stroke, and all-cause mortality by day 90.

CONCLUSIONS

Among high-risk patients undergoing cardiac surgery, delayed RIPC significantly reduced the occurrence of AKI.

REGISTRATION

URL: https://www.chictr.org.cn; Unique identifier: ChiCTR2000035568.

Cardiopulmonary Bypass Blood Flow Rates and Major Adverse Kidney Events in Cardiac Surgery: A Propensity Score-adjusted Before-After Study

OBJECTIVES

Cardiac surgery associated-acute kidney injury is a common and serious postoperative complication of cardiac surgery, which is associated with increased postoperative morbidity and mortality. This study aimed to explore the association between cardiopulmonary bypass (CPB) blood flow rate (BFR), and major adverse kidney events (MAKEs) at day 30.

DESIGN

Retrospective single-center before-after observational study. Patients were divided in 2 groups according to CPB flow rates: a first group with an institutional protocol targeting a CPB-BFR of >2.2 L/min/m² (low CPB-BFR group), and a second group with a modified institutional protocol targeting a CPB-BFR of >2.4 L/min/m² (high CPB-BFR group). The primary outcome was MAKE at 30 days, defined as the composite of death, renal replacement therapy or persistent renal dysfunction.

SETTING

The data were collected from clinical routines in university hospital.

PARTICIPANTS

Adult patients who underwent elective and urgent cardiac surgery without severe chronic renal failure, for whom CPB duration was ≥90 minutes.

INTERVENTIONS

We included 533 patients (low CPB-BFR group, n = 270; high CPB-BFR group, n = 263).

MEASUREMENTS AND MAIN RESULTS

A significant decrease in MAKE at 30 days was observed in the high CPB-BFR group (3% v 8%; odds ratio [OR], 0.779; 95% confidence interval [CI], 0.661-0.919; p < 0.001) mainly mediated by a lower 30-day mortality in the high CPB-BFR group (1% v 5%; OR, 0.697; 95% CI, 0.595-0.817; p = 0.001), as was renal replacement therapy (1% v 4%; OR, 0.739; 95% CI, 0.604-0.904; p = 0.016).

CONCLUSIONS

In patients undergoing cardiac surgery, increased CPB-BFR was associated with a decrease in MAKE at 30 days including mortality and renal replacement therapy.

Carboxyhemoglobin as Potential Biomarker for Cardiac Surgery Associated Acute Kidney Injury

OBJECTIVES

Carboxyhemoglobin (CO-Hb) is a marker of hemolysis and inflammation, both risk factors for cardiac surgery-associated AKI (CSA-AKI). However, the association between CO-Hb and CSA-AKI remains unknown.

DESIGN

A retrospective cohort study.

SETTING

Tertiary university-affiliated metropolitan hospital: single center.

PARTICIPANTS

Adult on-pump cardiac surgery patients from July 2014 to June 2022 (N = 1,698).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were stratified into quartiles based on CO-Hb levels at intensive care unit (ICU) admission. A progressive increased risk of CSA-AKI was observed with higher CO-Hb levels at ICU admission. On multivariable logistic regression analysis, the highest quartile (CO-Hb ≥ 1.4%) showed an independent association with the occurrence of CSA-AKI (odds ratio 1.45 compared to the lowest quartile [CO-Hb < 1.0%], 95% CI 1.023-2.071; p = 0.038). Compared to patients with CO-Hb <1.4%, patients with CO-Hb ≥ 1.4% at ICU admission had significantly higher postoperative creatinine (135 vs 116 μmol/L, p < 0.001), higher rates of postoperative RRT (6.7% vs 2.3%, p < 0.001) and AKI (p < 0.001) on univariable analysis and shorter time to event for AKI or death (p < 0.001).

CONCLUSIONS

CO-Hb ≥ 1.4% at ICU admission is an independent risk factor for CSA-AKI, which is easily obtainable and available on routine arterial blood gas measurements. Thus, CO-Hb may serve as a practical and biologically logical biomarker for risk stratification and population enrichment in trials of CSA-AKI prevention.

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.

Urine output is an early and strong predictor of acute kidney injury and associated mortality: a systematic literature review of 50 clinical studies

BACKGROUND

Although the present diagnosis of acute kidney injury (AKI) involves measurement of acute increases in serum creatinine (SC) and reduced urine output (UO), measurement of UO is underutilized for diagnosis of AKI in clinical practice. The purpose of this investigation was to conduct a systematic literature review of published studies that evaluate both UO and SC in the detection of AKI to better understand incidence, healthcare resource use, and mortality in relation to these diagnostic measures and how these outcomes may vary by population subtype.

METHODS

The systematic literature review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Data were extracted from comparative studies focused on the diagnostic accuracy of UO and SC, relevant clinical outcomes, and resource usage. Quality and validity were assessed using the National Institute for Health and Care Excellence (NICE) single technology appraisal quality checklist for randomized controlled trials and the Newcastle-Ottawa Quality Assessment Scale for observational studies.

RESULTS

A total of 1729 publications were screened, with 50 studies eligible for inclusion. A majority of studies (76%) used the Kidney Disease: Improving Global Outcomes (KDIGO) criteria to classify AKI and focused on the comparison of UO alone versus SC alone, while few studies analyzed a diagnosis of AKI based on the presence of both UO and SC, or the presence of at least one of UO or SC indicators. Of the included studies, 33% analyzed patients treated for cardiovascular diseases and 30% analyzed patients treated in a general intensive care unit. The use of UO criteria was more often associated with increased incidence of AKI (36%), than was the application of SC criteria (21%), which was consistent across the subgroup analyses performed. Furthermore, the use of UO criteria was associated with an earlier diagnosis of AKI (2.4-46.0 h). Both diagnostic modalities accurately predicted risk of AKI-related mortality.

CONCLUSIONS

Evidence suggests that the inclusion of UO criteria provides substantial diagnostic and prognostic value to the detection of AKI.

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

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

Urinary oxygen tension and its role in predicting acute kidney injury: A narrative review

Acute kidney injury occurs frequently in the perioperative setting. The renal medulla often endures hypoxia or hypoperfusion and is susceptible to the imbalance between oxygen supply and demand due to the nature of renal blood flow distribution and metabolic rate in the kidney. The current available evidence demonstrated that the urine oxygen pressure is proportional to the variations of renal medullary tissue oxygen pressure. Thus, urine oxygenation can be a candidate for reflecting the change of oxygen in the renal medulla. In this review, we discuss the basic physiology of acute kidney injury, as well as techniques for monitoring urine oxygen tension, confounding factors affecting the reliable measurement of urine oxygen tension, and its clinical use, highlighting its potential role in early detection and prevention of acute kidney injury.

Results of the inoperable and operable with aortic valve endocarditis

Objectives

To evaluate the results of the inoperable and operable with aortic valve endocarditis, focus on risk factors, significance, and management of destruction of the aortic annulus in aortic valve endocarditis.

Methods

The retrospective study was completed to investigate patients with aortic valve endocarditis undergoing cardiac surgery between January 2006 and November 2022 at our hospital.

Results

512 patients were divided into group with destruction of the aortic annulus (n = 80) and without destruction of the aortic annulus (n = 432). There were 32 operative deaths (6.3%, 32/512). By univariate and multivariate analysis, destruction of the aortic annulus is found to be statistically significantly associated with in-hospital mortality (P < 0.001), prolonged mechanical ventilation time (mechanical ventilation time > 96 h, P = 0.018), early aortic paravalvular leak (P < 0.001), and 1-year mortality following cardiac surgery (P < 0.001), respectively.

Conclusions

In our study, destruction of the aortic annulus increases mortality and health care costs. Optimization of pre-, peri-, and postoperative factors can reduce mortality and morbidity in aortic valve endocarditis. Aortic root replacement could be recommended as the best practice choice for aortic valve endocarditis with periannular abscess and destruction of the aortic annulus.

Quantifying the effects of circulatory arrest on acute kidney injury in aortic surgery

OBJECTIVES

We aim to investigate the association between parameters surrounding circulatory arrest and postoperative acute kidney injury in aortic surgery.

METHODS

This is a single-center retrospective study of 1118 adult patients who underwent aortic repair with median sternotomy between January 2010 and May 2019. Acute kidney injury was defined on the basis of a modified version of the 2012 Kidney Disease Improving Global Outcomes Scale that excluded urine output. The primary outcome of interest was any stage of acute kidney injury.

RESULTS

Circulatory arrest was required in 369 patients, and 307 patients (27.5%) developed acute kidney injury: stage 1 in 241 patients, stage 2 in 38 patients, and stage 3 in 28 patients. Lower-body ischemia (the period during circulatory arrest without blood flow to kidneys) duration was not associated with acute kidney injury after multivariable logistic regression (1-40 minutes, odds ratio, 0.67; 95% confidence interval, 0.43-1.04; P = .075; >40 minutes, odds ratio, 0.67; 95% confidence interval, 0.29-1.55; P = .356). Hypertension (odds ratio, 1.65; 95% confidence interval, 1.09-2.54; P = .020), preoperative estimated glomerular filtration rate (odds ratio, 0.99; 95% confidence interval, 0.98-1.00; P = .010), packed red blood cell transfusion volume (odds ratio, 1.00; 95% confidence interval, 1.00-1.00; P = .028), and nadir temperature (odds ratio, 0.93; 95% confidence interval, 0.88-0.99; P = .013) were independently associated with acute kidney injury after multivariable analysis. Although there was a positive association between lower-body ischemia duration and development of acute kidney injury with univariable cubic spline, the positive curve was flattened after adjustment for the described variables.

CONCLUSIONS

Within the range of our clinical practice, prolonged lower-body ischemia duration was not independently associated with postoperative acute kidney injury, whereas nadir temperature was.

Risk factors of prolonged intensive care unit stay following cardiac surgery for infective endocarditis

INTRODUCTION

Prolonged intensive care unit (ICU) stay is common in serious patients undergoing cardiac surgery. Prolonged ICU stay is associated with increased mortality and worse prognosis. This study was conducted to determine the risk factors for prolonged ICU stay after cardiac surgery for infective endocarditis (IE) and we try to decrease the operative risk of mortality and morbidity of cardiac surgery for IE.

METHODS

The retrospective study of patients with IE undergoing cardiac surgery between January 2006 and November 2022 at our hospital was performed.

RESULTS

896 patients undergoing cardiac surgery were divided into group of ICU stay ≤ 3d (n = 416) and group p of ICU stay > 3d (n = 480). There were 48 operative deaths (5.4%). Univariable and multivariable analyses showed that factors are associated with prolonged ICU stay following cardiac surgery for IE, including male (P < .001), age (P < .001), weight (P = .009), vegetation length (P < .001), paravalvular leak (P < .001), aortic cross-clamp time (P < .001), cardiopulmonary bypass (CPB) time (P < .001), mechanical ventilation time (P < .001), hospitalized time postoperative (P = .032), creatinine of serum before surgery (P < .001), creatinine of serum 24h after surgery (P = .005), creatinine of serum 48h after surgery (P < .001), fluid balance on operation day (P < .001), postoperative acute kidney injury (P < .001), left ventricular end diastolic dimension (LVEDD) preoperative (P < .001), LVEDD postoperative (P < .001), chest drainage (P = .032), frozen plasma (P = .016), preoperative aortic insufficiency (P < .001), and packed red cells (P < .001).

CONCLUSIONS

In our study, shortness of ICU stay and optimization of pre-, peri-, and postoperative factors that can shorten ICU stay, therefore, contribute to a better postoperative outcome and leads to lower rates of mortality and morbidity.

Surgical treatment of left-sided infective endocarditis with symptomatic neurological complications before surgery in China

Introduction

We aimed to investigate surgical treatment of left-sided infective endocarditis with symptomatic neurological complications before surgery.

Methods

This was a retrospective study of patients with left-sided infective endocarditis and symptomatic neurological complications before surgery undergoing cardiac surgery between January 2006 and November 2022 at our hospital.

Results

Eight hundred thirty-two patients were divided into group with symptomatic neurological complications before surgery (n = 112) and without symptomatic neurological complications before surgery (n = 720). There were 48 operative deaths (5.4%). Univariate and multivariate analyses showed that symptomatic neurological complications before surgery is statistically significantly associated with in-hospital mortality following cardiac surgery and prolonged intubation time.

Conclusions

Our study showed that symptomatic neurological complications before surgery are associated with increased in-hospital mortality following cardiac surgery and prolonged intubation time.

Impact of Vegetation Length on Clinical Complications During Surgical Intervention and Long-Term Survival in Infective Endocarditis

We aimed to investigate the impact of vegetation length on clinical complications during surgical intervention and long-term survival in infective endocarditis. This was a retrospective study of patients with infective endocarditis who underwent cardiac surgery between January 2006 and November 2022 at our hospital. 896 patients were divided into 2 groups: group I (vegetation length <10 mm, n = 448) and group II (vegetation length ≥10 mm, n = 448). There were 48 operative deaths (5.4%). Univariate and multivariate analyses showed that vegetation length is statistically significantly associated with destruction of the annulus (p <0.001), neurological complications before surgery (p <0.001), acute renal injury (p <0.001), prolonged intubation time (intubation time >24 hours) (p <0.001), prolonged intensive care unit (ICU) retention time (ICU retention time >3 days) (p <0.001), and in-hospital mortality (p <0.001), respectively. Our study showed that vegetation length is statistically significantly associated with destruction of the annulus, neurological complications before surgery, acute renal injury, prolonged intubation time, prolonged ICU retention time, in-hospital mortality, and 1-year mortality, respectively.

Goal-directed perfusion for reducing acute kidney injury in cardiac surgery: A systematic review and meta-analysis

BACKGROUND

Acute kidney injury (AKI) is a common complication following cardiopulmonary bypass (CPB) which can affect morbidity and mortality. Goal-directed perfusion (GDP) intended to avoid the nadir oxygen delivery index below the critical value is associated with reduced postoperative AKI. However, current studies suggested that GDP can only decrease the incidence of AKI stage 1 but showed no effects on AKI stages 2-3 and mortality. The objective of the present meta-analysis is to deter the effects of GDP on postoperative AKI in any stage and mortality following cardiac surgery.

METHODS

MEDLINE, Embase, and the Cochrane Library were searched to identify all clinical trials comparing GDP with control (standard care) during cardiopulmonary bypass conducting in adults undergoing cardiac surgery. The primary outcome was postoperative acute kidney injury. Secondary outcomes included postoperative mortality and length of ICU stay. Data synthesis was obtained by using risk ratio with 95% confidence interval by a random-effects model.

RESULT

From 1094 potential studies, 3 trials enrolling 777 patients were included. Meta-analysis suggested the GDP strategy based on DO₂i reduced postoperative AKI compared with standard CPB management (RR = 0.52; 95% CI: 0.38-0.70; p < .0001), especially in AKI stage I (RR = 0.47; 95% CI: 0.33-0.66; p < .0001). But the GDP strategy did not reduce the incidence of severe AKI (stages 2-3) and postoperative mortality.

CONCLUSION

The GDP strategy based on DO₂i during CPB obviously reduces AKI stage 1 and thus reduces overall AKI incidence. But it shows no effects on severe AKI (stages 2-3) and mortality.

Impact of previous REnal TRansplantation on the mid-term renal Outcome after CARdiac surgery: the RETROCAR trial

BACKGROUND

Acute kidney injury (AKI) is one of the most common complications after cardiac surgery with cardiopulmonary bypass (CPB). Renal transplant recipients (RTRs) have a higher risk of cardiac surgery-associated AKI (CSA-AKI). A relationship has been strongly suggested between AKI and poor long-term graft survival. The main objective was to evaluate the impact of on-pump cardiac surgery on the 1-year renal allograft survival rate.

METHODS

The study population consisted of 37 RTRs and 56 non-RTRs who underwent cardiac surgery between 1 January 2010 and 31 December 2019. They were matched according to age, sex, preoperative glomerular function, diabetes and type of surgery. The primary composite outcome was renal survival, defined as patient survival without the requirement for permanent dialysis or new kidney transplantation at 1 year after surgery.

RESULTS

The renal survival rate was significantly lower in the RTR group than in the non-RTR group [81% versus 96%; odds ratio 0.16 (95% confidence interval 0.03-0.82), P = .03]. The proportion of patients who returned to permanent dialysis was higher in the RTR group than in the non-RTR group (12% versus 0%; P = .02). The proportion of patients with severe AKI was also higher in the RTR group. At 1 year after surgery, serum creatinine level, glomerular filtration rate and all-cause mortality rates were comparable between both groups.

CONCLUSION

Patients with a functional renal allograft have a low 1-year renal allograft survival rate after cardiac surgery with CPB. In addition, these patients have significant risks of AKI and acute kidney disease after open-heart surgery.

Incidence, predictors and vascular sequelae of distal limb ischemia in minimally invasive cardiac surgery with femoral artery cannulation: an observational cohort study

Literature regarding monitoring and consequences of distal limb ischemia due to femoral artery cannulation for Minimally Invasive Cardiac Surgery (MICS) remains limited. The primary objective was to determine its incidence, defined as a ≥ 15% difference in regional Oxygen Saturation (rSO₂) lasting ≥ four consecutive minutes between the cannulated and non-cannulated limb. The secondary objectives included: determination of distal limb ischemia, defined as a Tissue Oxygenation Index (TOI) < 50% in the cannulated limb, identification of predictors for distal limb ischemia, determination of a possible association of NIRS-diagnosed ischemia with acute kidney injury, and the need for vascular surgery up to six months after cardiac surgery. A prospective, observational cohort study with blinded rSO₂-measurements to prevent intraoperative clinical decision-making. A single-center, community-hospital, clinical study. All consecutive patients ≥ 18 years old, and scheduled for predefined MICS. Patients underwent MICS with bilateral calf muscle rSO₂-measurements conducted by Near-Infrared Spectroscopy (NIRS). In total 75/280 patients (26.79%) experienced distal limb ischemia according to the primary objective, while 18/280 patients (6.42%) experienced distal limb ischemia according to the secondary objective. Multivariate logistic regression showed younger age to be an independent predictor for distal limb ischemia (p = 0.003). None of the patients who suffered intraoperative ischemia required vascular surgery within the follow-up period. The incidence of NIRS-diagnosed ischemia varied from 6.4% to 26.8% depending on the used criteria. Short and long-term vascular sequelae, however, are limited and not intraoperative ischemia related. The added value of intraoperative distal limb NIRS monitoring for vascular reasons seems limited. Future research on femoral artery cannulation in MICS should shift focus to other outcome parameters such as acute kidney injury, postoperative pain or paresthesias.

Development and internal validation of a prediction model for acute kidney injury following cardiac valve replacement surgery

BACKGROUND

Acute kidney injury (AKI) is a common complication after cardiac surgery. This study aims to develop and validate a risk model for predicting AKI after cardiac valve replacement surgery.

METHODS

Data from patients undergoing surgical valve replacement between January 2015 and December 2018 in our hospital were retrospectively analyzed. The subjects were randomly divided into a derivation cohort and a validation cohort at a ratio of 7:3. The primary outcome was defined as AKI within 7 days after surgery. Logistic regression analysis was conducted to select risk predictors for developing the prediction model. Receiver operator characteristic curve (ROC), calibration plot and clinical decision curve analysis (DCA) will be used to evaluate the discrimination, precision and clinical benefit of the prediction model.

RESULTS

A total of 1159 patients were involved in this study. The prevalence of AKI following surgery was 37.0% (429/1159). Logistic regression analysis showed that age, hemoglobin, fibrinogen, serum uric acid, cystatin C, bicarbonate, and cardiopulmonary bypass time were independent risk factors associated with AKI after surgical valve replacement (all P < 0.05). The areas under the ROC curves (AUCs) in the derivation cohort and the validation cohort were 0.777 (95% CI 0.744-0.810) and 0.760 (95% CI 0.706-0.813), respectively. The calibration plots indicated excellent consistency between the prediction probability and actual probability. DCA demonstrated great clinical benefit of the prediction model.

CONCLUSIONS

We developed a prediction model for predicting AKI after cardiac valve replacement surgery that was internally validated to have good discrimination, calibration, and clinical practicability.

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

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

Altered kidney function induced by SARS-CoV-2 infection and acute kidney damage markers predict survival outcomes of COVID-19 patients: a prospective pilot study

BACKGROUND

Literature with regard to coronavirus disease 2019 (COVID-19) associated morbidities and the risk factors for death are still emerging. In this study, we investigated the presence of kidney damage markers and their predictive value for survival among hospitalized subjects with COVID-19.

METHODS

Forty-seven participants was included and grouped as: 'COVID-19 patients before treatment', 'COVID-19 patients after treatment', 'COVID-19 patients under treatment in intensive care unit (ICU)', and 'controls'. Kidney function tests and several kidney injury biomarkers were compared between the groups. Cumulative rates of death from COVID-19 were determined using the Kaplan-Meier method. The associations between covariates including kidney injury markers and death from COVID-19 were examined, as well.

RESULTS

Serum creatinine and cystatin C levels, urine Kidney Injury Molecule-1 (KIM-1)/creatinine ratio, and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), CKD-EPI cystatin C, and CKD-EPI creatinine-cystatin C levels demonstrated significant difference among the groups. The most significant difference was noted between the groups 'COVID-19 patients before treatment' and 'COVID-19 patients under treatment in ICU'. Advancing age, proteinuria, elevated serum cystatin C, and urine KIM-1/creatinine ratio were all significant univariate correlates of death (p < 0.05, for all). However, only elevated urine KIM-1/creatinine ratio retained significance in an age, sex, and comorbidities adjusted multivariable Cox regression (OR 6.11; 95% CI: 1.22-30.53; p = 0.02), whereas serum cystatin C showing only a statistically non-significant trend (OR 1.42; 95% CI: 0.00-2.52; p = 0.09).

CONCLUSIONS

Our findings clearly demonstrated the acute kidney injury related to COVID-19. Moreover, urine KIM-1/creatinine ratio was associated with COVID-19 specific death.

Analysis of risk factors of multiorgan failure after pericardiectomy for constrictive pericarditis

Background

We aimed to investigate risk factors of multiorgan failure following pericardiectomy.

Methods

This was a retrospective study of patients undergoing pericardiectomy between January 1994 and May 2021 at three hospitals.

Results

826 patients were included in the study and divided into two groups: group with multiorgan failure (n = 86) and group without multiorgan failure (n = 740). There were 86 patients with multiorgan failure (86/826, 10.4%). There were 66 operative deaths (66/826, 8.0%). The causes of operative deaths were multiorgan failure, including cardiogenic shock + AKI + ventricular fibrillation (13/66), cardiogenic shock + AKI (35/66), cardiogenic shock + AKI + hepatic failure + septicemia (8/66), cardiogenic shock + AKI + respiratory failure (10/66). Univariate and multivariate analyses showed the factors associated with multiorgan failure, including male (P = 0.006), time between symptoms and surgery (P < 0.001), thickness of pericardium (P < 0.001), intubation time (P < 0.001), ICU retention time (P < 0.001), hospitalized time postoperative (P < 0.001), preoperative central venous pressure (P < 0.001), postoperative central venous pressure (P < 0.001), D0 fluid balance (P < 0.001), D2 fluid balance (P < 0.001), postoperative chest drainage (P < 0.001), preoperative LVEDD(P < 0.001), postoperative LVEDD (P < 0.001), surgical duration (P < 0.001), bleeding during operation (P < 0.001), serum creatinine 24 h after surgery (P = 0.042), serum creatinine 48 h after surgery (P < 0.001), fresh-frozen plasma (P < 0.001), packed red cells (P < 0.001), blood lactate (P < 0.001).

Conclusion

In our study, incomplete pericardial dissection, fluid overload, delayed diagnosis and treatment are associated with multiorgan failure following pericardiectomy.

Postoperative physiological parameters associated with severe acute kidney injury after pediatric heart transplant

BACKGROUND

The primary objective was to evaluate associations between perioperative clinical variables and postoperative hemodynamic indices after HT with the development of severe AKI. The secondary objective was to evaluate associations between UOP or creatinine as AKI indicators and morbidity after HT.

METHODS

Retrospective study of all patients who underwent HT 1/2016-11/2019 at a quaternary pediatric institution. Severe AKI was defined as KDIGO stage 2 or higher.

RESULTS

Of 94 HT patients, 73 met inclusion criteria; 45% of patients developed severe AKI. In univariate analysis, non-Hispanic Black race, preoperative AKI, longer CPB duration, lower weight, and peak lactate within 12 h post-HT were associated with severe AKI. CVP ≤12 h post-HT had a quadratic relationship, rather than linear, with severe AKI. PPV >18% was significantly associated with severe AKI but equated to noncontiguous 10 min of high variation over a 12-h period, and thus was deemed not clinically significant. In multivariate analysis, Black race, longer CPB duration, and higher CVP remained associated with severe AKI (c: 0.84, 95% CI 0.73-0.92). Severe AKI per creatinine, but not UOP criteria, was associated with longer duration of ventilation (p = .012) and longer intensive care unit length of stay (p = .003).

CONCLUSIONS

In pediatric HT patients, non-Hispanic Black race, longer CPB time, and higher postoperative CVP ≤12 h post-HT were associated with severe AKI. AKI based on creatinine, not UOP, was associated with postoperative HT morbidity.

Overview of Diagnostic Criteria and Epidemiology of Acute Kidney Injury and Acute Kidney Disease in the Critically Ill Patient

Since the description ischuria renalis by William Heberden (1), AKI has remained a prominent complication of critical illness. Beyond KRT, treatment has been limited by the capacity to phenotype this condition. Here, we chronicle the evolution of attempts to classify AKI, including the adoption of consensus definitions, the expansion of diagnosis and prognosis with novel biomarkers, and emerging tools such as artificial intelligence (AI).

Plasma haemolysis index and interleukine-6 for the early prediction of cardiac surgery-associated acute kidney injury. A proof-of-concept study

Introduction

Haemolysis and inflammation contribute to cardiac surgery-associated acute kidney injury (CS-AKI). We aimed to assess the performance of plasma haemolysis index (HI) and interleukine-6 (IL-6) for the prediction of all-stage CS-AKI. We also assessed their ability to predict moderate-to-severe CS-AKI and to discriminate persistent from transient CS-AKI.

Methods

Adult patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) were prospectively included. Haemolysis index and IL-6 were measured immediately after the end of CPB and 6 hours later. Correction for haemodilution relied upon changes in albuminaemia. Persistent CS-AKI was defined as a steady/increasing CS-AKI stage between the 48th and the 60th postoperative hour as compared with the worst stage observed within the 48 first hours.

Results

Among 82 patients, CS-AKI occurred in 37 (45%) patients. Postoperative HI and IL-6 were positively correlated to the duration of CPB (r ≤ 0.51, p ≤ 0.0003). Whether we considered isolated measurements of HI or IL-6, their indexation to haemodilution or not, their kinetics and/or their combination, the prediction of all stage CS-AKI was inaccurate (area under the receiver operating characteristic curve [AUCROC]≤ 0.68) whereas moderate-to-severe CS-AKI (6 patients only) was predicted with an honourable performance (AUCROC = 0.77 [95%CI 0.67;0.86] and 0.87 [95%CI 0.77;0.93] for HI and IL-6, respectively). The persistent/transient nature of CS-AKI was inaccurately predicted (AUCROC ≤ 0.68).

Conclusions

In a population in which most CS-AKI cases were mild, although they frequently (41%) persisted >48 hours, CS-AKI was inaccurately predicted by HI and/or IL-6. A better performance for moderate-to-severe CS-AKI prediction is likely. These preliminary findings are yet to be validated.

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

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

Early recognition of cardiac surgery-associated acute kidney injury: lack of added value of TIMP2 IGFBP7 over short-term changes in creatinine (an observational pilot study)

Background

For the detection of cardiac surgery-associated acute kidney injury (CS-AKI), the performance of urine tissue inhibitor of metalloproteinase 2 insulin-like growth factor-binding protein 7 (TIMP2 IGFBP7) has never been compared with that of very early changes in plasma creatinine (∆pCr). We hypothesized that, in the context of perioperative haemodilution, lack of postoperative decrease in pCr would be of honourable performance for the detection of CS-AKI. We therefore aimed at comparing these biomarkers and their kinetics (primary objective). As secondary objectives, we assessed plasma neutrophil gelatinase-associated lipocalin (pNGAL), cystatin C (pCysC) and urea (pUrea). We also determined the ability of these biomarkers to early discriminate persistent from transient CS-AKI.

Methods

Patients over 75 years-old undergoing aortic valve replacement with cardiopulmonary bypass (CPB) were included in this prospective observational study. Biomarkers were measured before/after CPB and at the sixth postoperative hour (H6).

Results

In 65 patients, CS-AKI occurred in 27 (42%). ∆pCr from post-CPB to H6 (∆pCr_postCPB-H6): outperformed TIMP2 IGFBP7 at H6 and its intra- or postoperative changes: area under the receiver operating characteristic curve (AUC_ROC) of 0.84 [95%CI:0.73–0.92] vs. ≤0.67 [95%CI:0.54–0.78], p ≤ 0.03. The AUC_ROC of pNGAL, pCysC and pUrea did not exceed 0.72 [95%CI:0.59–0.83]. Indexing biomarkers levels for blood or urine dilution did not improve their performance. Combining TIMP2 IGFBP7 and ∆pCr_postCPB-H6 was of no evident added value over considering ∆pCr_postCPB-H6 alone. For the early recognition of persistent CS-AKI, no biomarker outperformed ∆pCr_postCPB-H6 (AUC_ROC = 0.69 [95%CI:0.48–0.85]).

Conclusions

In this hypothesis-generating study mostly testing early detection of mild CS-AKI, there was no evident added value of the tested modern biomarkers over early minimal postoperative changes in pCr: despite the common perioperative hemodilution in the setting of cardiac surgery, if pCr failed to decline within the 6 h after CPB, the development of CS-AKI was likely. Confirmatory studies with more severe forms of CS-AKI are required.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01387-6.

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.

Early identification of acute kidney injury in the ICU with real-time urine output monitoring: a clinical investigation

Background

KDIGO (Kidney Disease: Improving Global Outcomes) provides two sets of criteria to identify and classify acute kidney injury (AKI): serum creatinine (SCr) and urine output (UO). Inconsistencies in the application of KDIGO UO criteria, as well as collecting and classifying UO data, have prevented an accurate assessment of the role this easily available biomarker can play in the early identification of AKI.

Study goal

To assess and compare the performance of the two KDIGO criteria (SCr and UO) for identification of AKI in the intensive care unit (ICU) by comparing the standard SCr criteria to consistent, real-time, consecutive, electronic urine output measurements.

Methods

Ninety five catheterized patients in the General ICU (GICU) of Hadassah Medical Center, Israel, were connected to the RenalSense™ Clarity RMS™ device to automatically monitor UO electronically (UO_elec). UO_elec and SCr were recorded for 24–48 h and up to 1 week, respectively, after ICU admission.

Results

Real-time consecutive UO measurements identified significantly more AKI patients than SCr in the patient population, 57.9% (N = 55) versus 26.4% (N = 25), respectively (P < 0.0001). In 20 patients that had AKI according to both criteria, time to AKI identification was significantly earlier using the UO_elec criteria as compared to the SCr criteria (P < 0.0001). Among this population, the median (interquartile range (IQR)) identification time of AKI UO_elec was 12.75 (8.75, 26.25) hours from ICU admission versus 39.06 (25.8, 108.64) hours for AKI SCr.

Conclusion

Application of KDIGO criteria for AKI using continuous electronic monitoring of UO identifies more AKI patients, and identifies them earlier, than using the SCr criteria alone. This can enable the clinician to set protocol goals for earlier intervention for the prevention or treatment of AKI.

Diagnosis of Cardiac Surgery-Associated Acute Kidney Injury

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

Noninvasive Urine Oxygen Monitoring and the Risk of Acute Kidney Injury in Cardiac Surgery

BACKGROUND

Acute kidney injury (AKI) is a common complication of cardiac surgery. An intraoperative monitor of kidney perfusion is needed to identify patients at risk for AKI. The authors created a noninvasive urinary oximeter that provides continuous measurements of urinary oxygen partial pressure and instantaneous urine flow. They hypothesized that intraoperative urinary oxygen partial pressure measurements are feasible with this prototype device and that low urinary oxygen partial pressure during cardiac surgery is associated with the subsequent development of AKI.

METHODS

This was a prospective observational pilot study. Continuous urinary oxygen partial pressure and instantaneous urine flow were measured in 91 patients undergoing cardiac surgery using a novel device placed between the urinary catheter and collecting bag. Data were collected throughout the surgery and for 24 h postoperatively. Clinicians were blinded to the intraoperative urinary oxygen partial pressure and instantaneous flow data. Patients were then followed postoperatively, and the incidence of AKI was compared to urinary oxygen partial pressure measurements.

RESULTS

Intraoperative urinary oxygen partial pressure measurements were feasible in 86/91 (95%) of patients. When urinary oxygen partial pressure data were filtered for valid urine flows greater than 0.5 ml · kg-1 · h-1, then 70/86 (81%) and 77/86 (90%) of patients in the cardiopulmonary bypass (CPB) and post-CPB periods, respectively, were included in the analysis. Mean urinary oxygen partial pressure in the post-CPB period was significantly lower in patients who subsequently developed AKI than in those who did not (mean difference, 6 mmHg; 95% CI, 0 to 11; P = 0.038). In a multivariable analysis, mean urinary oxygen partial pressure during the post-CPB period remained an independent risk factor for AKI (relative risk, 0.82; 95% CI, 0.71 to 0.95; P = 0.009 for every 10-mmHg increase in mean urinary oxygen partial pressure).

CONCLUSIONS

Low urinary oxygen partial pressures after CPB may be associated with the subsequent development of AKI after cardiac surgery.

EDITOR’S PERSPECTIVE

Predicting acute kidney injury following nonemergent cardiac surgery: A preoperative scorecard

OBJECTIVE

To determine the predictors of postoperative acute kidney injury (AKI) following nonemergent cardiac surgery among patients with variable preoperative estimated glomerular filtration rate (eGFR) levels.

METHODS

A retrospective study of patients who underwent elective or in-hospital cardiac surgical procedures was performed between January 2006 and November 2015. The procedures included isolated coronary artery bypass grafting (CABG), isolated aortic valve replacement (AVR), or combined CABG and AVR. The primary outcome AKI (any stage) following nonemergent cardiac surgery utilizing the 2012 Kidney Disease-Improving Global Outcomes (KDIGO) criteria. Patients were categorized based on the following renal outcomes: mild AKI, severe AKI (KDIGO stage 2 or 3), and postoperative dialysis. Patients with G5 preoperative kidney function (including dialysis patients) were excluded.

RESULTS

A total of 6675 patients were included in our study. The mean age was 66.8 years (SD ± 10.4), with 76.3% being males. A total of 4487 patients had normal or mildly decreased eGFR (G1 or G2) preoperatively (67.2%), while 1960 patients were in the G3 category (29.4%). Only 228 patients (3.4%) had G4 renal function. A total of 1453 (21.7%) patients experienced postoperative AKI. The need for postoperative dialysis occurred in 3.2% of the AKI subgroup. In-hospital mortality was higher among the AKI subgroup (7.2% vs. 0.5%; p < .0001). In an adjusted model, a lower preoperative eGFR category was the strongest predictor of AKI. A practical scorecard for the preoperative estimation of severe AKI for nonemergent cardiac procedures incorporating these parameters was developed.

CONCLUSIONS

Preoperative eGFR is the strongest predictor of postoperative AKI in individuals undergoing nonemergent cardiac surgery. A practical scorecard incorporating preoperative predictors of AKI may allow informed decision-making and predict AKI following nonemergent cardiac surgery.

Identification of risk factors for renal failure after cardiac surgery by RFILE classification

OBJECTIVE

Acute kidney injury (AKI) is a major complication after cardiovascular surgery. The unclear etiology of this highly complex event challenges definition, diagnosis and prediction of AKI, and hence hampers adequate patient management. Identification of associated risk factors have the potential to overcome this limitation.

METHODS

This retrospective study comprised 3574 patients who underwent cardiac surgery in a hospital in Germany. The patient cohort was interrogated for risk factors for AKI.

RESULTS

The analysis identified risk factors for AKI development, such as type of surgery (particularly bypass surgery) (P = 0.02), previous coronary surgeries (P < 0.01), the application of intra-aortic balloon pump in surgery (P < 0.01), and blood loss during surgery (P < 0.01). In addition, old age, duration of surgery as well as ischemia, perfusion and reperfusion times contributed to AKI development (P < 0.01). Further, perioperative hypothermia also appeared as putative risk factor in the analysis (P < 0.01).

CONCLUSIONS

This study identified several risk factors for the development of AKI after cardiac surgery. Further validation of these risk factors could allow the implementation of adequate patient management, and the appropriate implementation of risk-adverse interventions in cardiovascular surgery.

Prognostic Utility of KDIGO Urine Output Criteria After Cardiac Surgery

OBJECTIVES

Kidney Disease: Improving Global Outcomes (KDIGO) guidelines include assessment of creatinine and urine output to identify acute kidney injury (AKI). Whether urine output is an accurate indicator of AKI after cardiac surgery, however, is unclear. The authors' goal was to examine whether cardiac surgery patients who fulfilled criteria for AKI by KDIGO urine output criteria also demonstrated kidney injury by elevated creatinine, other kidney biomarkers, or had worse clinical outcomes.

DESIGN

Secondary analysis of prospectively collected data from a clinical trial, "6% Hydroxyethyl starch 130/0.4 in Cardiac Surgery (NCT02192502)."

SETTING

Academic, quaternary care hospital.

PARTICIPANTS

Patients undergoing elective aortic valve replacement INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: One hundred forty-one patients were classified into AKI stage by KDIGO urine output criteria within 24 hours after surgery. Kidney biomarkers (serum creatinine, urinary neutrophil gelatinase-associated lipocalin [NGAL], urinary interleukin-18 [IL-18]) and hospital and intensive care unit length of stay were analyzed across AKI stages. Urine output criteria classified four times as many patients with AKI than creatinine criteria (95 [67%] v 21 [15%]). Most patients meeting KDIGO urine output criteria for AKI postoperatively did not satisfy KDIGO creatinine criteria for AKI within one week (77 of 95 [81%]) or six-to-12 months (27 of 29 [93%]). Higher AKI stage assessed by urine output was not associated with higher NGAL, IL-18, or longer hospital or intensive care unit stays.

CONCLUSIONS

Acute kidney injury classified by KDIGO urine output criteria was not associated with other biomarkers of kidney injury or worse patient outcomes. These data suggested that KDIGO urine output criteria after cardiac surgery may overclassify AKI stage; further research is needed.

Intraoperative Urinary Biomarkers and Acute Kidney Injury After Cardiac Surgery

OBJECTIVES

To evaluate the association of intraoperative urinary biomarker excretion during cardiac surgery and the subsequent development of acute kidney injury (AKI).

DESIGN

Prospective, nonrandomized, observational study.

SETTING

Single tertiary-level, university-affiliated hospital.

PARTICIPANTS

Ninety patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Urinary samples were collected every 30 minutes intraoperatively and then at four, 12, and 24 hours after CPB. Samples were measured for interleukin 18 (IL-18), kidney injury molecule-1 (KIM1), and creatinine concentrations. Urinary biomarker excretion (raw and indexed to creatinine) for four intraoperative and three postoperative points were compared between patients with and those without subsequent AKI defined by increased serum creatinine concentration ≥0.3 mg/dL within the first 48 hours or ≥1.5 times baseline within seven days. Raw and indexed median IL-18 values were similar between AKI groups at all intraoperative points, but became significantly different at 12 hours after CPB. Raw and indexed median KIM1 values were significantly different between AKI groups at multiple intraoperative points and at four and 12 hours after CPB. During intraoperative and postoperative points, patients in the fourth quartile of KIM1 excretion had greater AKI incidence and longer intensive care and hospital lengths of stay than those in the first quartile. Only postoperatively did the differences in these outcomes between the fourth and first quartile of IL-18 excretion occur.

CONCLUSIONS

Intraoperative KIM1 but not IL-18 excretion was associated with postoperative development of AKI.

Risk assessment of acute kidney injury following cardiopulmonary bypass

BACKGROUND

Acute kidney injury (AKI) is a frequent and serious complication of cardiac surgery, associated with a high incidence of morbidity and mortality. Although the RIFLE criteria serve as a prominent tool to identify patients at high risk of AKI, an optimized diagnosis model in clinical practice is desired.

METHODS

Based on the SOP-criteria, 365 patients (10%) developed AKI following surgery and were subjected to RRT. In contrast, the incidence of AKI, defined according to the RIFLE criteria, was only 7% (n = 251 patients). Prominent risk factors identified by SOP were patients' sex, valve and combined valve and bypass surgery, deep hypothermia, use of intra-aortic balloon pump (IABP) and previous coronary interventions. Ischemia, reperfusion, blood loss and surgery time also served as significant risk factors for patient evaluated by SOP.

RESULTS

Risk assessment by RIFLE differed in as much as most patients with normothermia and those receiving only cardiovascular bypass developed AKI. However, patients' sex and valve surgery did not serve as a risk factor.

CONCLUSION

Evaluation of patients by the RIFLE versus SOP criteria yielded different results with more AKI patients detected by SOP. Based on the present data, it is concluded that patients may not prone to AKI when surgery and ischemia time will be kept short, when blood loss is mitigated to a minimum and when surgery is performed under non-hypothermic conditions.

Copeptin concentration following cardiac surgery as a prognostic marker of postoperative acute kidney injury: a prospective cohort study

Background

Copeptin, the C-terminal portion of the arginine vasopressin precursor, is a novel candidate biomarker. This study investigated the prognostic value of copeptin levels following cardiac surgery for the occurrence of postoperative acute kidney injury.

Methods

We studied 23 patients who underwent cardiac surgery between January 2018 and December 2019. The primary endpoint was postoperative acute kidney injury onset. Copeptin levels were measured before, right after, and daily for 7 days. The patients were divided into two groups according to the copeptin levels: low (values <43.7 pmol/L) and high (values ≥43.7 pmol/L). Correlations between copeptin levels and variables, such as central venous pressure, were assessed by bivariate analysis.

Results

The high copeptin group exhibited significantly higher levels of arginine vasopressin and cortisol following surgery, compared to those of the low copeptin group. The copeptin concentration following surgery was correlated to central venous pressure (P=0.03) and norepinephrine administered dose (P=0.008). Also, the copeptin levels right after surgery robustly predicted the onset of postoperative acute kidney injury (area under the receiver operating characteristic curve of 0.83, P=0.004).

Conclusions

Elevated copeptin levels in patients following cardiac surgery predicted postoperative acute kidney injury development. Therefore, the copeptin concentration after surgery could represent a promising clinical biomarker of the postoperative cardiac outcome.

A Novel Patient-Specific Model for Predicting Severe Oliguria; Development and Comparison With Kidney Disease: Improving Global Outcomes Acute Kidney Injury Classification

OBJECTIVES

The Kidney Disease: Improving Global Outcomes urine output criteria for acute kidney injury lack specificity for identifying patients at risk of adverse renal outcomes. The objective was to develop a model that analyses hourly urine output values in real time to identify those at risk of developing severe oliguria.

DESIGN

This was a retrospective cohort study utilizing prospectively collected data.

SETTING

A cardiac ICU in the United Kingdom.

PATIENTS

Patients undergoing cardiac surgery between January 2013 and November 2017.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

Patients were randomly assigned to development (n = 981) and validation (n = 2,389) datasets. A patient-specific, dynamic Bayesian model was developed to predict future urine output on an hourly basis. Model discrimination and calibration for predicting severe oliguria (< 0.3 mL/kg/hr for 6 hr) occurring within the next 12 hours were tested in the validation dataset at multiple time points. Patients with a high risk of severe oliguria (p > 0.8) were identified and their outcomes were compared with those for low-risk patients and for patients who met the Kidney Disease: Improving Global Outcomes urine output criterion for acute kidney injury. Model discrimination was excellent at all time points (area under the curve > 0.9 for all). Calibration of the model's predictions was also excellent. After adjustment using multivariable logistic regression, patients in the high-risk group were more likely to require renal replacement therapy (odds ratio, 10.4; 95% CI, 5.9-18.1), suffer prolonged hospital stay (odds ratio, 4.4; 95% CI, 3.0-6.4), and die in hospital (odds ratio, 6.4; 95% CI, 2.8-14.0) (p < 0.001 for all). Outcomes for those identified as high risk by the model were significantly worse than for patients who met the Kidney Disease: Improving Global Outcomes urine output criterion.

CONCLUSIONS

This novel, patient-specific model identifies patients at increased risk of severe oliguria. Classification according to model predictions outperformed the Kidney Disease: Improving Global Outcomes urine output criterion. As the new model identifies patients at risk before severe oliguria develops it could potentially facilitate intervention to improve patient outcomes.

Definition of hourly urine output influences reported incidence and staging of acute kidney injury

Background

Acute kidney injury (AKI) is commonly defined using the KDIGO system, which includes criteria based on reduced urine output (UO). There is no consensus on whether UO should be measured using consecutive hourly readings or mean output. This makes KDIGO UO definition and staging of AKI vulnerable to inconsistency which has implications both for research and clinical practice. The objective of this study was to investigate whether the way in which UO is defined affects incidence and staging of AKI.

Methods

We conducted a retrospective analysis of two single centre observational studies investigating (i) patients undergoing cardiac surgery and (ii) patients admitted to general intensive care units (ICU). AKI was identified using KDIGO serum creatinine (SCr) criteria and two methods of UO (UO^cons: UO meeting KDIGO criteria in each consecutive hour; UO^mean: mean hourly UO meeting KDIGO criteria).

Results

Data from 151 CICU and 150 ICU admissions were analysed. Incidence of AKI using SCr alone was 23.8% in CICU and 32% in ICU. Incidence increased in both groups when UO was considered, with inclusion of UO^mean more than doubling reported incidence of AKI (CICU: UO^cons 39.7%, UO^mean 72.8%; ICU: UO^cons 51.3%, UO^mean 69.3%). In both groups UO^cons led to a larger increase in KDIGO stage 1 but UO^mean increased the incidence of KDIGO stage 2.

Conclusions

We demonstrate a serious lack of clarity in the internationally accepted AKI definition leading to significant variability in reporting of AKI incidence.

The impact of acute kidney injury by serum creatinine or urine output criteria on major adverse kidney events in cardiac surgery patients

OBJECTIVES

Oliguria after cardiac surgery remains of uncertain clinical significance. Therefore, we investigated the relationship of acute kidney injury severity across urine output and creatinine domains with the risk for major adverse kidney events at 180 days. We aimed to determine the impact of acute kidney injury after cardiac surgery.

METHODS

In a retrospective multicenter study, we investigated the relationship of acute kidney injury severity across urine output and creatinine categories with the risk for major adverse kidney events at 180 days-the composite of death, dialysis, and persistent renal dysfunction-using a large database of patients undergoing cardiac surgery at 1 of 5 hospitals within the regional medical system. We analyzed electronic records from 6637 patients treated between 2008 and 2014, of whom 5389 (81.2%) developed any acute kidney injury within 72 hours of surgery. We stratified patients by levels of urine output or serum creatinine according to Kidney Disease Improving Global Outcomes criteria for acute kidney injury.

RESULTS

Major adverse kidney events at 180 days increased from 4.5% for no acute kidney injury to 61.3% for stage 3 acute kidney injury (P < .001). Death or dialysis by day 180 was 2.4% for those with no acute kidney injury and 46.7% for those with acute kidney injury stage 3 (P < .001). Isolated oliguria was common (42.6%), and isolated azotemia was rare (6.1%). Even stage 1 acute kidney injury by oliguria alone was associated with an increased risk of major adverse kidney events at 180 days (odds ratio, 1.76; 1.20-2.57; P = .004), mainly driven by persistent renal dysfunction (odds ratio, 2.01; 1.26-3.18; P = .003).

CONCLUSIONS

Acute kidney injury is common in patients undergoing cardiac surgery, and even milder forms of acute kidney injury, including isolated stage 1 oliguria, are associated with adverse long-term consequences.

Stage 1 acute kidney injury is independently associated with infection following cardiac surgery

OBJECTIVES

Severe acute kidney injury (AKI) is a known risk factor for infection and mortality. However, whether stage 1 AKI is a risk factor for infection has not been evaluated in adults. We hypothesized that stage 1 AKI following cardiac surgery would independently associate with infection and mortality.

METHODS

In this retrospective propensity score-matched study, we evaluated 1620 adult patients who underwent nonemergent cardiac surgery at the University of Colorado Hospital from 2011 to 2017. Patients who developed stage 1 AKI by Kidney Disease Improving Global Outcomes creatinine criteria within 72 hours of surgery were matched to patients who did not develop AKI. The primary outcome was an infection, defined as a new surgical-site infection, positive blood or urine culture, or development of pneumonia. Secondary outcomes included in-hospital mortality, stroke, and intensive care unit (ICU) and hospital length of stay (LOS).

RESULTS

Stage 1 AKI occurred in 293 patients (18.3%). Infection occurred in 20.9% of patients with stage 1 AKI compared with 8.1% in the no-AKI group (P < .001). In propensity-score matched analysis, stage 1 AKI independently associated with increased infection (odds ratio [OR]; 2.24, 95% confidence interval [CI], 1.37-3.17), ICU LOS (OR, 2.38; 95% CI, 1.71-3.31), and hospital LOS (OR, 1.30; 95% CI, 1.17-1.45).

CONCLUSIONS

Stage 1 AKI is independently associated with postoperative infection, ICU LOS, and hospital LOS. Treatment strategies focused on prevention, early recognition, and optimal medical management of AKI may decrease significant postoperative morbidity.

Perioperative renal protection

PURPOSE OF REVIEW

The present article reviews the recent literature on the main aspects of perioperative acute kidney injury (AKI).

RECENT FINDINGS

AKI occurs in 1 in every 10 surgical patients, with cardiac, orthopedic, and major abdominal surgeries being the procedures associated with the highest risk. Overall, complex operations, bleeding, and hemodynamic instability are the most consistent procedure-related risk factors for AKI. AKI increases hospital stay, mortality, and chronic kidney disease, gradually with severity. Furthermore, delayed renal recovery negatively impacts on patients' outcomes. Cell cycle arrest biomarkers seem promising to identify high-risk patients who may benefit from the bundles recommended by the Kidney Disease: Improving Global Outcomes guidelines. Hemodynamic management using protocol-based administration of fluids and vasopressors helps reducing AKI. Recent studies have highlighted the benefit of personalizing the blood pressure target according to the patient's resting reference, and avoiding both hypovolemia and fluid overload. Preliminary research has reported encouraging renoprotective effects of angiotensin II and nitric oxide, which need to be confirmed. Moreover, urinary oxygenation monitoring appears feasible and a fair predictor of postoperative AKI.

SUMMARY

AKI remains a frequent and severe postoperative complication. A personalizedmulticomponent approach might help reducing the risk of AKI and improving patients' outcomes.

Five-year outcomes after thoracic endovascular aortic repair of symptomatic type B penetrating aortic ulcer with intramural hematoma in Chinese patients

Background

The aim of this study is to evaluate the five-year outcomes after thoracic endovascular aortic repair (TEVAR) of symptomatic Stanford type B penetrating aortic ulcer (PAU) associated with intramural hematoma (IMH) in Chinese patients.

Methods

From January 2009 to April 2013, 118 patients with typical severe acute chest pain were diagnosed with Stanford type B acute aortic syndrome (AAS) in our department and received TEVAR. Within the group, 28 patients were diagnosed with PAU associated with IMH by computed tomography angiography (CTA) and subsequently evaluated with repeated CTA. All 28 patients' clinical and follow-up data were collected for 60 months.

Results

PAU associated with IMH continued to progress for approximately 14 days and sometimes a few days more. Twenty-eight patients underwent TEVAR under general anesthesia via femoral artery access. Technical success was achieved in 100% of cases. Two stent grafts were used in 1 patient to achieve effective coverage of the PAUs and IMH. The follow-up rate was 92.8%. Two patients were lost to follow-up in the 4^th and 16^th months due to relocation. All patients remained free of aortic symptoms during follow-up. Two heavy smoker patients in whom the ostium of the left subclavian artery (LSCA) was completely covered by the graft had transient dizziness upon resumption of smoking during follow-up. There were 2 early type II endoleaks but no aortic expansion. No patient needed reintervention. One patient died in a car accident at 42 months. Four patients safely underwent noncardiovascular surgery. The 1-, 2-, and 5-year overall survival rates were 100%, 100%, and 96.1%, respectively.

Conclusions

The short- and mid-term results of TEVAR treatment for symptomatic Stanford type B PAU associated with IMH in Chinese patients were encouraging. Long-term follow-up is anticipated.