Cardiac and Vascular Surgery-Associated Acute Kidney Injury: The 20th International Consensus Conference of the ADQI (Acute Disease Quality Initiative) Group

Development of acute kidney injury following repair of Stanford type A aortic dissection is associated with increased mortality and complications: a systematic review, meta-analysis, and meta-regression analysis

Acute kidney injury (AKI) frequently complicates the repair of Stanford type A aortic dissection (TAAD). This systematic review, meta-analysis, and meta-regression analysis aimed to elucidate the prognostic impact of AKI in these patients. A literature search in PubMed, EMBASE, and Google Scholar identified relevant studies on the predictors and outcomes of AKI following TAAD repair. The primary endpoint was 30-day mortality; secondary endpoints included stroke, dialysis/continuous renal replacement therapy (CRRT), and other complications. Random-effects meta-analyses were used, with significance set at P < 0.05. Twenty-one studies (10 396 patients) were analyzed. AKI was associated with higher risks of 30-day mortality (risk ratio = 3.98), stroke (risk ratio = 2.05), dialysis/CRRT (risk ratio = 32.91), cardiovascular (risk ratio = 2.85) and respiratory complications (risk ratio = 2.13), sepsis (risk ratio = 4.92), and re-exploration for bleeding (risk ratio = 2.46). No significant differences were noted in sternal wound infection, tracheostomy, paraplegia, or hepatic failure. AKI significantly increases mortality, morbidity, hospital, and ICU stay duration in TAAD repair patients.

Cardiopulmonary bypass associated acute kidney injury: better understanding and better prevention

Cardiopulmonary bypass (CPB) is a common technique in cardiac surgery but is associated with acute kidney injury (AKI), which carries considerable morbidity and mortality. In this review, we explore the range and definition of CPB-associated AKI and discuss the possible impact of different disease recognition methods on research outcomes. Furthermore, we introduce the specialized equipment and procedural intricacies associated with CPB surgeries. Based on recent research, we discuss the potential pathogenesis of AKI that may result from CPB, including compromised perfusion and oxygenation, inflammatory activation, oxidative stress, coagulopathy, hemolysis, and endothelial damage. Finally, we explore current interventions aimed at preventing and attenuating renal impairment related to CPB, and presenting these measures from three perspectives: (1) avoiding CPB to eliminate the fundamental impact on renal function; (2) optimizing CPB by adjusting equipment parameters, optimizing surgical procedures, or using improved materials to mitigate kidney damage; (3) employing pharmacological or interventional measures targeting pathogenic factors.

Cardiac surgery-Associated acute kidney injury - A narrative review

Cardiac Surgery-Associated Acute Kidney Injury (CSA-AKI) is a serious complication seen in approximately 20-30% of cardiac surgery patients. The underlying pathophysiology is complex, often involving both patient- and procedure related risk factors. In contrast to AKI occurring after other types of major surgery, the use of cardiopulmonary bypass comprises both additional advantages and challenges, including non-pulsatile flow, targeted blood flow and pressure as well as the ability to manipulate central venous pressure (congestion). With an increasing focus on the impact of CSA-AKI on both short and long-term mortality, early identification and management of high-risk patients for CSA-AKI has evolved. The present narrative review gives an up-to-date summary on definition, diagnosis, underlying pathophysiology, monitoring and implications of CSA-AKI, including potential preventive interventions. The review will provide the reader with an in-depth understanding of how to identify, support and provide a more personalized and tailored perioperative management to avoid development of CSA-AKI.

Diagnostic accuracy of NT-proBNP to predict the incidence of CSA-AKI: A systematic review and meta-analysis

BACKGROUND

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a severe complication following cardiac surgery. Early identification and diagnosis are critical. In this study, we aim to systematically assess the diagnostic value of N-terminal pro-B-type natriuretic peptide (NT-proBNP) for CSA-AKI.

METHODS

The PubMed, Embase, Web of Science, and Cochrane Library databases were searched from January 1971 to October 2023 to identify prospective observational and retrospective observational studies. Data extraction and study screening were carried out independently by 2 authors. The methodological quality of the included studies was evaluated by the Quality Assessment of Diagnostic Accuracy Studies 2 standards, and all statistical analyses were conducted by Stata 15.0.

RESULTS

Seven studies including 37,200 patients were identified. The pooled sensitivity of 0.67 (95% credible interval [CI] = 0.56-0.77), specificity of 0.55 (95% CI = 0.45-0.64), area under the summary receiver operating characteristic curve of 0.65 (95% CI = 0.60-0.69), positive likelihood ratio of 1.5 (95% CI = 1.2-1.8), negative likelihood ratio of 0.60 (95% CI = 0.46-0.79), and diagnostic odds ratio of 2 (95% CI = 2-4) suggested that patients with higher preoperative NT-proBNP levels (pg/mL) are at higher risk of developing acute kidney injury after cardiac surgery. However, NT-proBNP lacks sufficient sensitivity and specificity to reliably predict CSA-AKI.

CONCLUSION

Our findings suggest that the diagnostic accuracy of NT-proBNP to predict the incidence of CSA-AKI is limited. However, we provide novel perspectives on the early detection of CSA-AKI biomarkers, and it is urgent to identify more precise and practical biomarkers for the early diagnosis of CSA-AKI.

Ultrafiltration During Cardiac Surgery Requiring Cardiopulmonary Bypass and Its Effect on Acute Kidney Injury

OBJECTIVE

To explore whether ultrafiltration (UF) volume adjusted for weight is associated with an increased risk of acute kidney injury (AKI) after cardiopulmonary bypass (CPB) in cardiac surgery patients.

DESIGN

A retrospective cohort study.

SETTING

Single-center study at a tertiary academic medical center.

PARTICIPANTS

A total of 2369 adult patients (age ≥18 years) who underwent cardiac surgery with CPB between January 2018 and August 2019.

INTERVENTION

The cohort was divided into 4 groups based on weight-adjusted conventional UF volume: 0 (no UF), 0.1 to 17.9 mL, 18 to 29.9 mL, and >30 mL ultrafiltration for each kg of body weight. Demographic data, laboratory findings, comorbidities, medications, and surgical details were collected. Postoperative AKI was defined by the KDIGO (Kidney Disease: Improving Global Outcomes) staging criteria and assessed in all UF groups. The association between UF volume and AKI according to nadir hemoglobin (Hb) level and red blood cell transfusion volume was explored.

RESULTS

Postoperative AKI occurred in 840 patients (35.4%). The incidence of AKI post-CPB in patients was similar in patients with 0 mL/kg (34.4%; n = 123), 0.1 to 17.9 mL/kg (34.3%; n = 387), and 18 to 29.9 mL/kg (33.7%; n = 173) of UF volume. The patients with UF volume >30 mL/kg had a higher incidence of AKI (42.7%; n = 157; p = 0.019). For each additional 10 mL/kg increase in UF, the odds ratio (OR) of AKI was 1.14 (95% confidence interval [CI], 1.07-1.20; p < 0.001) following adjustments for preoperative covariates. However, the association was mitigated following adjustments for preoperative and intraoperative covariates (OR, 1.07; 95% CI, 0.99-1.16; p = 0.076). Although higher UF also was associated with an increased risk of AKI in patients with nadir Hb levels of 6 to 8 g/dL (adjusted OR, 1.24 and 1.22; p = 0.02), it was not significantly associated with AKI when nadir Hb was 10 to 12 g/dL. Red blood cell transfusion volume was not related to changes in AKI incidence.

CONCLUSIONS

This study suggests that conventional UF is a potential risk factor for AKI incidence following surgery with CPB. The results demonstrate an association between higher weight-adjusted ultrafiltration volume and a higher incidence of AKI. Future studies should incorporate a multicenter, prospective approach to test the generalizability of the present findings and validate modified ultrafiltration strategies that use hemodynamic variables to determine fluid removal volume.

Factors associated with acute kidney injury after on-pump coronary artery bypass grafting

BACKGROUND

Acute kidney injury (AKI) frequently occurs as a complication of cardiac surgery and cardiopulmonary bypass (CPB). Its prevalence and severity are determined by various preoperative and intraoperative factors. The aim of this study was to examine the risk factors for AKI following on-pump coronary artery bypass grafting (CABG).

METHODS

A retrospective analysis of clinical records from a single medical center was performed. The primary determinant for AKI analysis was the creatinine-level changes within the first 48 h after surgery. Records of 120 patients from a prospective cohort study were examined.

RESULTS

An AKI incidence of 26% occurred in the study cohort. The univariate analysis revealed that patients who developed AKI had notably higher EuroSCORE II values (2.00 ± 0.98 vs. 1.49 ± 0.74, p = 0.006) and higher initial levels of urea (7.62 ± 2.94 vs. 6.12 ± 1.71, p = 0.002) and creatinine (0.108 ± 0.039 vs. 0.091 ± 0.016, p = 0.003). Additionally, they exhibited a more frequent occurrence of initial albumin levels below 40 g/l (9 (34.6%) vs. 11 (14.9%) cases, p = 0.030) and a lower initial hemoglobin level (137.8 ± 13.2 g/l vs. 146.6 ± 13.6 g/l, p = 0.005) in comparison to patients without this complication. Moreover, those with AKI had a significantly longer hospital stay duration (14.3 ± 5.45 days vs. 12.6 ± 3.05 days, p = 0.048). Logistic regression indicated one risk factor, oxygen delivery during CPB, that correlated with the onset of AKI in the early postoperative period.

CONCLUSION

The prevalence of AKI was higher among patients with a higher EuroSCORE II, lower preoperative hemoglobin, increased preoperative levels of creatinine and urea, infrequent albumin levels below 40 g/L, diminished oxygen delivery during CPB, and greater need for RBC transfusion and furosemide, but it did not correlate with the duration of CPB.

Continuous Urine Output-Based Alert Identifies Cardiac Surgery-associated Acute Kidney Injury Earlier Than Serum Creatinine: A Prospective and Retrospective Observational Study

OBJECTIVE(S)

Acute kidney injury (AKI) is defined and staged by reduced urine output (UO) and increased serum creatinine (SCr). UO is typically measured manually and documented in the electronic health record, making early and reliable detection of oliguria-based AKI and electronic data extraction challenging. The authors investigated the diagnostic performance of continuous UO, enabled by active drain line clearance-based alerts (Accuryn AKI Alert), compared with AKI stage 2 SCr criteria and their associations with length of stay, need for continuous renal replacement therapy, and 30-day mortality.

DESIGN

This study was a prospective and retrospective observational study.

SETTING

Nine tertiary centers participated.

PARTICIPANTS

Cardiac surgery patients were enrolled.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 522 patients were analyzed. AKI stages 1, 2, and 3 were diagnosed in 32.18%, 30.46%, and 3.64% of patients based on UO, compared with 33.72%, 4.60%, and 3.26% of patients using SCr, respectively. Continuous UO-based alerts diagnosed stage ≥1 AKI 33.6 (IQR =15.43, 95.68) hours before stage ≥2 identified by SCr criteria. A SCr-based diagnosis of AKI stage ≥2 has been designated a Hospital Harm by the Centers for Medicare & Medicaid Services. Using this criterion as a benchmark, AKI alerts had a discriminative power of 0.78. The AKI Alert for stage 1 was significantly associated with increased intensive care unit and hospital length of stay and continuous renal replacement therapy, and stage ≥2 alerts were associated with mortality.

CONCLUSIONS

AKI Alert, based on continuous UO and enabled by active drain line clearance, detected AKI stages 1 and 2 before SCr criteria. Early AKI detection allows for early kidney optimization, potentially improving patient outcomes.

Association between hyperglycemia at ICU admission and postoperative acute kidney injury in patients undergoing cardiac surgery: Analysis of the MIMIC-IV database

Background

This study aimed to explore the correlation between hyperglycemia at intensive care unit (ICU) admission and the incidence of acute kidney injury (AKI) in patients after cardiac surgery.

Methods

We conducted a retrospective cohort study, in which clinical data were extracted from the Medical Information Mart for Intensive Care (MIMIC)-IV database. Adults (≥18 years) in the database who were admitted to the cardiovascular intensive care unit after cardiac surgery were enrolled. The primary outcome was the incidence of AKI within 7 days following ICU admission. Secondary outcomes included ICU mortality, hospital mortality, ICU length of stay, and the 28-day and 90-day mortality. Multivariable Cox regression analysis was used to assess the association between ICU-admission hyperglycemia and AKI incidence within 7 days of ICU admission. Different adjustment strategies were used to adjust for potential confounders. Patients were divided into three groups according to their highest blood glucose levels recorded within 24 h of ICU admission: no hyperglycemia (<140 mg/dL), mild hyperglycemia (140-200 mg/dL), and severe hyperglycemia (≥200 mg/dL).

Results

Of the 6905 included patients, 2201 (31.9%) were female, and the median (IQR) age was 68.2 (60.1-75.9) years. In all, 1836 (26.6%) patients had severe hyperglycemia. The incidence of AKI within 7 days of ICU admission, ICU mortality, and hospital mortality was significantly higher in patients with severe admission hyperglycemia than those with mild hyperglycemia or no hyperglycemia (80.3% vs. 73.6% and 61.2%, respectively; 2.8% vs. 0.9% and 1.9%, respectively; and 3.4% vs. 1.2% and 2.5%, respectively; all P <0.001). Severe hyperglycemia was a risk factor for 7-day AKI (Model 1: hazard ratio [HR]=1.4809, 95% confidence interval [CI]: 1.3126 to 1.6707; Model 2: HR=1.1639, 95% CI: 1.0176 to 1.3313; Model 3: HR=1.2014, 95% CI: 1.0490 to 1.3760; all P <0.050). Patients with normal glucose levels (glucose levels <140 mg/dL) had a higher 28-day mortality rate than those with severe hyperglycemia (glucose levels ≥200 mg/dL) (4.0% vs. 3.8%, P <0.001).

Conclusions

In post-cardiac surgery patients, severe hyperglycemia within 24 h of ICU admission increases the risk of 7-day AKI, ICU mortality, and hospital mortality. Clinicians should be extra cautious regarding AKI among patients with hyperglycemia at ICU admission after cardiac surgery.

Association between Left Ventricular Geometry, Systolic Ejection Time, and Estimated Glomerular Filtration Rate in Ambulatory Patients with Preserved Left Ventricular Ejection Fraction

INTRODUCTION

Cardiac function is important to quantify for risk stratification. Although left ventricular ejection fraction (LVEF) is commonly used, and identifies patients with poor systolic function, other easily acquired measures of cardiac function are needed, particularly to stratify patients with relatively preserved LVEF. LV relative wall thickness (RWT) has been associated with adverse clinical outcomes in patients with preserved LVEF, but the clinical relevance of this observation is not known. The purpose of this study was to assess whether increased RWT is a marker of subclinical cardiac dysfunction as measured by a surrogate of LV dysfunction and left ventricular ejection time (LVET) and if increased RWT is independently associated with chronic kidney disease (CKD), an important clinical outcome and cardiovascular disease risk equivalent.

METHODS

This retrospective cohort study enrolled ambulatory patients 18 years and older undergoing routine transthoracic echocardiography (TTE) at Johns Hopkins Hospital from January 2017 to January 2018. Patients with LVEF <50%, severe valvular disease, or liver failure were excluded. Multivariable regression evaluated the relationship between RWT, LVET, and CKD adjusted for demographics, comorbidities, and vital signs.

RESULTS

We analyzed data from 375 patients with mean age (±SD) 52.2 ± 15.3 years of whom 58% were female. Mean ± SD of RWT was 0.45 ± 0.10, while mean ± SD of LVET was 270 ms ± 33. In multivariable linear regression adjusted for demographics, comorbidities, vital signs, and left ventricular mass, each 0.1 increase in RWT was associated with a decrease of 4.6 ms in LVET, indicating worse cardiac function (β, ± 95% CI) (-4.60, -7.37 to -1.48, p = 0.004). Of those with serum creatinine available 1 month before or after TTE, 20% (50/247) had stage 3 or greater CKD. In logistic regression (adjusted for sex, comorbidities, and medications), each 0.1 unit increase in RWT was associated with an 61% increased odds of CKD (aOR = 1.61, 1.03-2.53, p = 0.037). In multivariable ordinal regression adjusted for the same covariates, each 0.1 unit increase in RWT was associated with a 44% increased odds of higher CKD stage (aOR = 1.44, 1.03-2.02, p = 0.035). There was a trend but no statistically significant relationship between RWT and change in estimated glomerular filtration rate at 1 year.

CONCLUSION

In an outpatient cohort undergoing TTE, increased RWT was independently associated with a surrogate of subclinical systolic dysfunction (LVET) and CKD. This suggests that RWT, an easily derived measure of LV geometry on TTE, may identify clinically relevant subclinical systolic dysfunction and patients with worse kidney function. Additional investigation to further clarify the relationships between RWT, systolic function, and kidney dysfunction over time and how this information may guide clinical intervention are warranted.

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.

Evaluating the Prevalence of Cardiac Surgery-associated Acute Kidney Injury After Septal Myectomy Combined With Concomitant Procedures in Obstructive Hypertrophic Cardiomyopathy

OBJECTIVES

Hypertrophic obstructive cardiomyopathy (HOCM) may be treated by septal myectomy. Cardiac surgery-associated acute kidney injury (CSA-AKI) is a common complication, but little is known about its incidence after septal myectomy. The objectives of this work were to evaluate the prevalence of CSA-AKI after septal myectomy and identify potential perioperative and phenotype-related factors contributing to CSA-AKI.

DESIGN

This was a retrospective database analysis with new data analysis.

SETTING

The study occurred in a single university academic expertise center for septal myectomy HOCM patients.

PARTICIPANTS

Data from 238 HOCM patients with septal myectomy operated on between 2005 and 2022 were collected.

INTERVENTIONS

CSA-AKI was stratified according to the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines using measurement of creatinine and urine production. Important HOCM phenotype-related and perioperative factors were analyzed for their possible associations with CSA-AKI.

MEASUREMENTS AND MAIN RESULTS

CSA-AKI occurred in 45% of patients; of these, 55% were classified as KDIGO stage I and the remaining 45% as stage II, with no chronic kidney damage observed. Moreover, there were no phenotypical or perioperative characteristics that were more prevalent in the CSA-AKI cohort. However, the use of beta-blockers and coronary artery disease were more prevalent in the CSA-AKI cohort.

CONCLUSIONS

CSA-AKI is a common complication after septal myectomy but was transient, and kidney function recovered in all patients.

Early Acute Kidney Injury Recovery in Elderly Patients Undergoing Valve Replacement Surgery

OBJECTIVES

This study was designed to determine the incidence, contributing factors, and prognostic implications of acute kidney injury (AKI) recovery patterns in patients who experienced AKI after valve replacement surgery (VRS).

DESIGN

A retrospective cohort study was conducted.

SETTING

The work took place in a postoperative care center in a single large-volume cardiovascular center.

PARTICIPANTS

Patients undergoing VRS between January 2010 and December 2019 were enrolled.

INTERVENTION

Patients were categorized into three groups based on their postoperative AKI status: non-AKI, AKI with early recovery (less than 48 hours), and persistent AKI.

MEASUREMENT AND MAIN RESULTS

The primary outcome was in-hospital major adverse clinical events. The secondary outcomes included in-hospital and 1-year mortality. A total of 4,161 patients who developed AKI following VRS were included. Of these, 1,513 (36.4%) did not develop postoperative AKI, 1,875 (45.1%) experienced AKI with early recovery, and 773 (18.6%) had persistent AKI. Advanced age, diabetes, New York Heart Association III-IV heart failure, moderate-to-severe renal dysfunction, anemia, and AKI stages 2 and 3 were identified as independent risk factors for persistent AKI. In-hospital major adverse clinical events occurred in 59 (3.9%) patients without AKI, 88 (4.7%) with early AKI recovery, and 159 (20.6%) with persistent AKI (p < 0.001). Persistent AKI was independently associated with an increased risk of in-hospital adverse events and 1-year mortality. In contrast, AKI with early recovery did not pose additional risk compared with non-AKI patients.

CONCLUSIONS

In patients who develop AKI following VRS, early AKI recovery does not pose additional risk compared with non-AKI. However, AKI lasting more than 48 hours is associated with an increased risk of in-hospital and long-term adverse outcomes.

Characteristics of initiation timing and anticoagulation of continuous renal replacement therapy in patients following cardiac surgery: A retrospective analysis of 28 patients

Continuous renal replacement therapy (CRRT) used in cardiac surgery-associated acute kidney injury (CSA-AKI) may have different characteristics from other diseases. We reviewed the medical records of patients with CSA-AKI requiring CRRT who underwent cardiac surgery from January 2020 to September 2021. Patients with AKI caused by other reasons who received CRRT during the same period were also evaluated. A total of 28 patients with CSA-AKI and 12 patients with AKI caused by other reasons were enrolled in this study. Compared with AKI patients caused by other reasons, patients with CSA-AKI were found to have lower mean arterial pressure, higher level of bilirubin, higher vasoactive-inotropic score, and larger daily diuretic dosage. The patients with CSA-AKI were prescribed CRRT earlier than the patients with AKI caused by other reasons. There was a significant difference in the CRRT anticoagulation method between patients with CSA-AKI and patients with AKI caused by other reasons. Six patients with CSA-AKI were treated with regional citrate anticoagulation (RCA), and the other 22 patients were treated with low molecular weight heparin or without anticoagulants. The timing of CRRT initiation in patients with CSA-AKI is earlier than that in patients with AKI caused by other reasons. Although RCA is recommended as the preferred anticoagulant for patients without contraindications, patients with CSA-AKI often have circulatory dysfunction and severe liver damage, so the risk of citrate accumulation is greater, whether to use RCA should be determined according to the individual condition of the patient.

Recommendations for clinical trial design in acute kidney injury from the 31st acute disease quality initiative consensus conference. A consensus statement

PURPOSE

Novel interventions for the prevention or treatment of acute kidney injury (AKI) are currently lacking. To facilitate the evaluation and adoption of new treatments, the use of the most appropriate design and endpoints for clinical trials in AKI is critical and yet there is little consensus regarding these issues. We aimed to develop recommendations on endpoints and trial design for studies of AKI prevention and treatment interventions based on existing data and expert consensus.

METHODS

At the 31st Acute Disease Quality Initiative (ADQI) meeting, international experts in critical care, nephrology, involving adults and pediatrics, biostatistics and people with lived experience (PWLE) were assembled. We focused on four main areas: (1) patient enrichment strategies, (2) prevention and attenuation studies, (3) treatment studies, and (4) innovative trial designs of studies other than traditional (parallel arm or cluster) randomized controlled trials. Using a modified Delphi process, recommendations and consensus statements were developed based on existing data, with > 90% agreement among panel members required for final adoption.

RESULTS

The panel developed 12 consensus statements for clinical trial endpoints, application of enrichment strategies where appropriate, and inclusion of PWLE to inform trial designs. Innovative trial designs were also considered.

CONCLUSION

The current lack of specific therapy for prevention or treatment of AKI demands refinement of future clinical trial design. Here we report the consensus findings of the 31st ADQI group meeting which has attempted to address these issues including the use of predictive and prognostic enrichment strategies to enable appropriate patient selection.

Development and external validation of temporal fusion transformer models for continuous intraoperative blood pressure forecasting

Background

During surgery, intraoperative hypotension is associated with postoperative morbidity and should therefore be avoided. Predicting the occurrence of hypotension in advance may allow timely interventions to prevent hypotension. Previous prediction models mostly use high-resolution waveform data, which is often not available.

Methods

We utilised a novel temporal fusion transformer (TFT) algorithm to predict intraoperative blood pressure trajectories 7 min in advance. We trained the model with low-resolution data (sampled every 15 s) from 73,009 patients who were undergoing general anaesthesia for non-cardiothoracic surgery between January 1, 2017, and December 30, 2020, at the General Hospital of Vienna, Austria. The data set contained information on patient demographics, vital signs, medication, and ventilation. The model was evaluated using an internal (n = 8113) and external test set (n = 5065) obtained from the openly accessible Vital Signs Database.

Findings

In the internal test set, the mean absolute error for predicting mean arterial blood pressure was 0.376 standard deviations-or 4 mmHg-and 0.622 standard deviations-or 7 mmHg-in the external test set. We also adapted the TFT model to binarily predict the occurrence of hypotension as defined by mean arterial blood pressure < 65 mmHg in the next one, three, five, and 7 min. Here, model discrimination was excellent, with a mean area under the receiver operating characteristic curve (AUROC) of 0.933 in the internal test set and 0.919 in the external test set.

Interpretation

Our TFT model is capable of accurately forecasting intraoperative arterial blood pressure using only low-resolution data showing a low prediction error. When used for binary prediction of hypotension, we obtained excellent performance.

Funding

No external funding.

Acute Dapagliflozin Administration Ameliorates Cardiac Surgery-Associated Acute Kidney Injury in a Rabbit Model

BACKGROUND

 Several studies have shown that sodium-glucose cotransporter-2 inhibitors have a renoprotective effect on acute kidney injury (AKI), but their effect on cardiac surgery-associated AKI is unknown.

METHODS AND RESULTS

 AKI was induced in 25 rabbits without diabetes mellitus by cardiopulmonary bypass (CPB) for 2 h and they were divided into 5 groups: sham; dapagliflozin-treated sham; CPB; dapagliflozin-treated CPB; and furosemide-treated CPB (n=5 in each group). Dapagliflozin was administered via the femoral vein before initiating CPB. Kidney tissue and urine and blood samples were collected after the surgical procedure. There were no differences in the hemodynamic variables of each group. Dapagliflozin reduced serum creatinine and blood urea nitrogen concentrations, and increased overall urine output (all P<0.05). Hematoxylin and eosin staining showed that the tubular injury score was improved after dapagliflozin administration (P<0.01). Dapagliflozin administration mitigated reactive oxygen species and kidney injury molecule-1 as assessed by immunohistochemistry (both P<0.0001). Protein expression analysis showed improvement of inflammatory cytokines and apoptosis, and antioxidant enzyme expression was elevated (all P<0.05) through activation of the nuclear factor erythroid 2-related factor 2 pathway (P<0.01) by dapagliflozin.

CONCLUSIONS

 Acute intravenous administration of dapagliflozin protects against CPB-induced AKI. Dapagliflozin may have direct renoprotective effects in renal tubular cells.

A Randomized Trial of Intravenous Amino Acids for Kidney Protection

BACKGROUND

Acute kidney injury (AKI) is a serious and common complication of cardiac surgery, for which reduced kidney perfusion is a key contributing factor. Intravenous amino acids increase kidney perfusion and recruit renal functional reserve. However, the efficacy of amino acids in reducing the occurrence of AKI after cardiac surgery is uncertain.

METHODS

In a multinational, double-blind trial, we randomly assigned adult patients who were scheduled to undergo cardiac surgery with cardiopulmonary bypass to receive an intravenous infusion of either a balanced mixture of amino acids, at a dose of 2 g per kilogram of ideal body weight per day, or placebo (Ringer's solution) for up to 3 days. The primary outcome was the occurrence of AKI, defined according to the Kidney Disease: Improving Global Outcomes creatinine criteria. Secondary outcomes included the severity of AKI, the use and duration of kidney-replacement therapy, and all-cause 30-day mortality.

RESULTS

We recruited 3511 patients at 22 centers in three countries and assigned 1759 patients to the amino acid group and 1752 to the placebo group. AKI occurred in 474 patients (26.9%) in the amino acid group and in 555 (31.7%) in the placebo group (relative risk, 0.85; 95% confidence interval [CI], 0.77 to 0.94; P = 0.002). Stage 3 AKI occurred in 29 patients (1.6%) and 52 patients (3.0%), respectively (relative risk, 0.56; 95% CI, 0.35 to 0.87). Kidney-replacement therapy was used in 24 patients (1.4%) in the amino acid group and in 33 patients (1.9%) in the placebo group. There were no substantial differences between the two groups in other secondary outcomes or in adverse events.

CONCLUSIONS

Among adult patients undergoing cardiac surgery, infusion of amino acids reduced the occurrence of AKI. (Funded by the Italian Ministry of Health; PROTECTION ClinicalTrials.gov number, NCT03709264.).

Amino Acid Infusion for Perioperative Functional Renal Protection: A Meta-analysis

OBJECTIVES

Acute kidney injury (AKI) is a common perioperative complication. To date, no single intervention has been proven effective for AKI prevention in this setting. However, intravenous amino acids (AA) administration may recruit renal functional reserve and, thereby, attenuate the perioperative loss of the glomerular filtration rate.

DESIGN

We performed a meta-analysis to assess the efficacy of AA infusion for perioperative renal functional protection.

SETTING AND PARTICIPANTS

We performed a meta-analysis of controlled studies in perioperative patients evaluating intravenous AA infusion versus any comparator.

MEASUREMENTS

The primary outcome was AKI at longest follow-up. We performed a random effects meta-analysis on the relative risk (RR) scale to assess the effect of AA infusion. We used a Bayesian approach to estimate the probability of benefit (RR < 1) for the primary outcome. Secondary outcomes included renal replacement therapy, serum creatinine, and estimated glomerular filtration rate. Tertiary outcomes included mechanical ventilation duration, intensive care unit and hospital length of stay and mortality (PROSPERO: CRD42024547225).

RESULTS

We identified 15 studies (14 randomized controlled trials and 1 prospective before-after study) reporting at least one outcome of interest (4,544 patients), with 6 studies (4,084 patients) reporting the primary outcome. AKI occurred 504 of 2,041 (24.7%) in AA patients versus 614 of 2,041 (30.1%) in controls (RR, 0.66; 95% confidence interval, 0.47-0.94; I2 = 50%; p = 0.02), which corresponded with a 99.1% probability of AKI reduction with AA. Moreover, consistent with these findings, AA decreased serum creatinine and hospital length of stay and increased the estimated glomerular filtration rate.

CONCLUSIONS

This meta-analysis suggests that AA administration likely decreased the perioperative incidence of AKI.

Albumin: a comprehensive review and practical guideline for clinical use

PURPOSE

Nowadays, it is largely accepted that albumin should not be used in hypoalbuminemia or for nutritional purpose. The most discussed indication of albumin at present is the resuscitation in shock states, especially distributive shocks such as septic shock. The main evidence-based indication is also liver disease. In this review, we provided updated evidence-based instruction for definite and potential indications of albumin administration in clinical practice, with appropriate dosing and duration.

METHODS

Data collection was carried out until November 2023 by search of electronic databases including PubMed, Google Scholar, Scopus, and Web of Science. GRADE system has been used to determine the quality of evidence and strength of recommendations for each albumin indication.

RESULTS

A total of 165 relevant studies were included in this review. Fluid replacement in plasmapheresis and liver diseases, including hepatorenal syndrome, spontaneous bacterial peritonitis, and large-volume paracentesis, have a moderate to high quality of evidence and a strong recommendation for administering albumin. Moreover, albumin is used as a second-line and adjunctive to crystalloids for fluid resuscitation in hypovolemic shock, sepsis and septic shock, severe burns, toxic epidermal necrolysis, intradialytic hypotension, ovarian hyperstimulation syndrome, major surgery, non-traumatic brain injury, extracorporeal membrane oxygenation, acute respiratory distress syndrome, and severe and refractory edema with hypoalbuminemia has a low to moderate quality of evidence and weak recommendation to use. Also, in modest volume paracentesis, severe hyponatremia in cirrhosis has a low to moderate quality of evidence and a weak recommendation.

CONCLUSION

Albumin administration is most indicated in management of cirrhosis complications. Fluid resuscitation or treatment of severe and refractory edema, especially in patients with hypoalbuminemia and not responding to other treatments, is another rational use for albumin. Implementation of evidence-based guidelines in hospitals can be an effective measure to reduce inappropriate uses of albumin.

Beyond the Valve: Incidence, Outcomes, and Modifiable Factors of Acute Kidney Injury in Patients with Infective Endocarditis Undergoing Valve Surgery-A Retrospective, Single-Center Study

Background/Objectives: Infective endocarditis (IE) often requires surgical intervention, with postoperative acute kidney injury (AKI), posing a significant concern. This retrospective study aimed to investigate AKI incidence, its impact on short-term mortality, and identify modifiable factors in patients with IE scheduled for valve surgery. Methods: This single-center study enrolled 130 consecutive IE patients from 2013 to 2021 undergoing valve surgery. The creatinine levels were monitored pre- and postoperatively, and AKI was defined by Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Patient demographics, comorbidities, procedural details, and complications were recorded. Primary outcomes included AKI incidence; the relevance of creatinine levels for AKI detection; and the association of AKI with 30-, 60-, and 180-day mortality. Modifiable factors contributing to AKI were explored as secondary outcomes. Results: Postoperatively, 35.4% developed AKI. The highest creatinine elevation occurred on the second postoperative day. Best predictive value for AKI was a creatinine level of 1.35 mg/dL on the second day (AUC: 0.901; sensitivity: 0.89, specificity: 0.79). Elevated creatinine levels on the second day were robust predictors for short-term mortality at 30, 60, and 180 days postoperatively (AUC ranging from 0.708 to 0.789). CK-MB levels at 24 h postoperatively and minimum hemoglobin during surgery were identified as independent predictors for AKI in logistic regression. Conclusions: This study highlights the crucial role of creatinine levels in predicting short-term mortality in surgical IE patients. A specific threshold (1.35 mg/dL) provides a practical marker for risk stratification, offering insights for refining perioperative strategies and optimizing outcomes in this challenging patient population.

Optimization of kidney function in cardiac surgery patients with intra-abdominal hypertension: expert opinion

Cardiac surgery-associated acute kidney injury (CSA-AKI) affects up to 42% of cardiac surgery patients. CSA-AKI is multifactorial, with low abdominal perfusion pressure often overlooked. Abdominal perfusion pressure is calculated as mean arterial pressure minus intra-abdominal pressure (IAP). IAH decreases cardiac output and compresses the renal vasculature and renal parenchyma. Recent studies have highlighted the frequent occurrence of IAH in cardiac surgery patients and have linked the role of low perfusion pressure to the occurrence of AKI. This review and expert opinion illustrate current evidence on the pathophysiology, diagnosis, and therapy of IAH and ACS in the context of AKI.

Biomarker-guided detection of acute kidney injury in abdominal aortic surgery: the new and the old

Introduction

Acute kidney injury (AKI) is a common complication in patients undergoing major vascular surgery. Despite significant research efforts in this area, the incidence of AKI remains high, posing a significant challenge to healthcare systems, especially in situations where resources are limited. Early prediction of AKI severity and individualized postoperative care is therefore essential.

Methods

The primary objective of this exploratory study was to assess the diagnostic value of urine cell-cycle arrest biomarkers [(TIMP-2) × (IGFBP7)] and soluble urokinase plasminogen activator receptor (suPAR) for predicting moderate or severe AKI within 24 h after open aortic surgery, and compared to routine kidney biomarkers. Seventy-five patients undergoing elective aortic surgery were included. Clinical parameters, urine and blood samples were collected preoperatively, immediately postoperatively, and 24 h later. AKI was defined using KDIGO criteria. Individual and combined diagnostic performance of biomarkers were evaluated.

Results

Of the 75 patients, 61% developed AKI, of which 28% developed moderate or severe AKI within 24 h of surgery. Baseline demographics, comorbidities and kidney parameters did not differ between patients with moderate or severe AKI (AKI II/III) and none or mild AKI (AKI 0/I), except for higher preoperative suPAR levels in later AKI II/III patients. Urine osmolality, Cystatin C and serum creatinine had the highest predictive power for AKI II/III with AUCs of 0.75-0.72. (TIMP-2) × (IGFBP7), and neither (TIMP-2) × (IGFBP7) nor suPAR individually showed superior diagnostic value. Combining CysC or SCr with urine osmolality and 6 h urine output gave the best performance with AUCs of 0.86 (95% CI, 0.74-0.96) and 0.85 (95% CI, 0.75-0.95) respectively.

Conclusion

Our study suggests that routine parameters like urine osmolality, CysC, SCr and 6 h urine output perform best in predicting postoperative AKI after aortic surgery compared to the new biomarkers (TIMP-2) × (IGFBP7) and suPAR. Combining biomarkers, particularly CysC or SCr with urine output, urine osmolality, may enhance diagnostic accuracy. Further validation in larger cohorts and clinical settings is warranted to establish their clinical utility.

AKI-Pro score for predicting progression to severe acute kidney injury or death in patients with early acute kidney injury after cardiac surgery

BACKGROUND

No reliable clinical tools exist to predict acute kidney injury (AKI) progression. We aim to explore a scoring system for predicting the composite outcome of progression to severe AKI or death within seven days among early AKI patients after cardiac surgery.

METHODS

In this study, we used two independent cohorts, and patients who experienced mild/moderate AKI within 48 h after cardiac surgery were enrolled. Eventually, 3188 patients from the MIMIC-IV database were used as the derivation cohort, while 499 patients from the Zhongshan cohort were used as external validation. The primary outcome was defined by the composite outcome of progression to severe AKI or death within seven days after enrollment. The variables identified by LASSO regression analysis were entered into logistic regression models and were used to construct the risk score.

RESULTS

The composite outcome accounted for 3.7% (n = 119) and 7.6% (n = 38) of the derivation and validation cohorts, respectively. Six predictors were assembled into a risk score (AKI-Pro score), including female, baseline eGFR, aortic surgery, modified furosemide responsiveness index (mFRI), SOFA, and AKI stage. And we stratified the risk score into four groups: low, moderate, high, and very high risk. The risk score displayed satisfied predictive discrimination and calibration in the derivation and validation cohort. The AKI-Pro score discriminated the composite outcome better than CRATE score, Cleveland score, AKICS score, Simplified renal index, and SRI risk score (all P < 0.05).

CONCLUSIONS

The AKI-Pro score is a new clinical tool that could assist clinicians to identify early AKI patients at high risk for AKI progression or death.

The effectiveness of dexmedetomidine for preventing acute kidney injury after surgery: a systematic review and meta-analysis

Background

Postoperative acute kidney injury (AKI) is a serious and distressing complication connected to various adverse outcomes following the surgical operation. Controversy remains regarding the dexmedetomidine's preventive impact on postoperative AKI. Therefore, this investigation aims to explore the efficiency and safety of dexmedetomidine in preventing AKI after surgical operation.

Methods

We systematically searched electronic databases such as PubMed, Embase, Web of Science, and the Cochrane Library to detect eligible randomized controlled studies that used dexmedetomidine for the prevention of AKI following operation up to April 30, 2023. The main outcome evaluated was AKI incidence. The evidence quality was assessed employing the Grading of Recommendations Assessment, Development, and Evaluation.

Results

The meta-analysis included 25 trials, including 3,997 individuals. Of these, 2,028 were in the dexmedetomidine group, and 1,969 were in the control group. The result showed that patients administered dexmedetomidine significantly decreased the AKI incidence following surgical operation in contrast to the control group (risk ratio, 0.60; 95% confidence intervals, 0.45-0.78; p < 0.05; I 2 = 46%). In addition, dexmedetomidine decreased the period of hospitalization in both the intensive care unit (ICU) and the hospital while also reducing postoperative delirium (POD) occurrence. However, dexmedetomidine elevated the incidence of bradycardia but did not have a significant impact on other indicators.

Conclusion

Our meta-analysis indicates that the dexmedetomidine treatment reduces the postoperative AKI and POD risk while also shortening the time of hospitalization in the ICU and hospital. However, it is connected to an increased bradycardia risk.

Determinants of postoperative complications in high-risk noncardiac surgery patients optimized with hemodynamic treatment strategies: A post-hoc analysis of a randomized multicenter clinical trial

STUDY OBJECTIVE

This post-hoc analysis of a randomized controlled trial was undertaken to establish the determinants of postoperative complications and acute kidney injury in high-risk noncardiac surgery patients supported with hemodynamic treatment strategies.

DESIGN

We conducted a post-hoc analysis of patients enrolled in the OPtimization Hemodynamic Individualized by the respiratory QUotiEnt (OPHIQUE) trial.

SETTING

Operating rooms in four university medical centers and one non-university hospital from December 26, 2018, to September 9, 2021.

PATIENTS

We enrolled 350 patients with a high risk of postoperative complications undergoing high-risk noncardiac surgery lasting 2 h or longer under general anesthesia.

INTERVENTIONS

All patients were treated according to hemodynamic treatment strategies which included cardiac output optimization by titration of fluid challenge and targeted systolic blood pressure to remain within ±10% of the reference value.

MEASUREMENTS

We assessed the association between pre-operative and intra-operative exposure of interest with a composite primary outcome of major complications or death within seven days following surgery using a multivariable logistic regression model. We also assessed the association between these exposures of interest and acute kidney injury.

MAIN RESULTS

The data of 341 patients were analyzed. In multivariate analysis, the factors independently associated with the primary outcome were age (OR = 1.04 (1.01-1.06), P = 0.002), preoperative hemoglobin concentration (OR = 0.85 (0.75-0.96), P = 0.012), non-vascular surgery (OR = 0.30 (0.17-0.53), P < 0.0001), and intraoperative surgical complications (OR = 2.08 (1.02-4.24), P = 0.046). The factors independently associated with postoperative acute kidney injury were age (OR = 1.04 (1.01-1.08), P = 0.008), preoperative creatinine concentration (OR = 1.01 (1.00-1.01), P = 0.049), non-vascular surgery (OR = 0.36 (0.20-0.66), P = 0.001), and intraoperative surgical complications (OR = 3.36 (1.50-7.55), P = 0.031).

CONCLUSIONS

Surgical complications, a lower preoperative hemoglobin concentration, age, and vascular surgery were associated with postoperative complications in a high-risk noncardiac surgery population supported with hemodynamic treatment strategies.

Perioperative Evaluation of Arterial and Venous Whole Blood in the Lamb (Ovis aries) Fontan Model

Whole blood analysis can evaluate numerous parameters, including pH, pCO₂, pO₂, HCO₃ - , base excess, glucose, electrolytes, lactate, blood urea nitrogen, creatinine, bilirubin, and hemoglobin. This valuable tool enables clinicians to make more informed decisions about patient care. However, the current body of literature describing perioperative whole blood analysis in Dorset sheep (Ovis aries) is small, so clinicians lack adequate information to guide their decision-making when evaluating test results. We evaluated arterial and venous whole blood pH, bicarbonate, pCO₂, lactate, creatinine, and blood urea nitrogen before and for the first 24 hours after surgery in 2 cohorts of male and female Ovis arie s undergoing one of 2 major cardiovascular procedures, a Single-Stage Fontan or an inferior vena cava to pulmonary artery extracardiac conduit implantation (IP-ECC). The cohort undergoing a Single-Stage Fontan, which is the more complex procedure, exhibited greater deviation from baseline measurements than did the cohort undergoing the IP-ECC for lactate, bicarbonate, and creatinine. The cohort undergoing the IP-ECC showed no significant deviation from baseline for any parameters, potentially indicating a better safety margin than expected when compared with the Single-Stage Fontan. Together, these results indicate the clinical value of arterial and venous whole blood measurements in perioperative management of sheep and can provide a reference for clinicians managing sheep after significant cardiovascular procedures.

Adverse renal effects associated with cardiopulmonary bypass

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Population Pharmacokinetics of Caffeine in Neonates with Congenital Heart Disease and Associations with Acute Kidney Injury

Cardiac surgery-associated acute kidney injury (CS-AKI) occurs in approximately 65% of neonates undergoing cardiac surgery on cardiopulmonary bypass and contributes to morbidity and mortality. Caffeine may reduce CS-AKI by counteracting adenosine receptor upregulation after bypass, but pharmacokinetics (PK) in this population are unknown. The goal of our analysis is to address knowledge gaps in age-, disease-, and bypass-related effects on caffeine disposition and explore preliminary associations between caffeine exposure and CS-AKI using population PK modeling techniques and an opportunistic, electronic health record-integrated trial design. We prospectively enrolled neonates receiving preoperative caffeine per standard of care and collected PK samples. We retrospectively identified neonates without caffeine exposure undergoing surgery on bypass as a control cohort. We followed US Food and Drug Administration guidance for population PK model development using NONMEM. Effects of clinical covariates on PK parameters were evaluated. We simulated perioperative exposures and used multivariable logistic regression to evaluate the association between caffeine exposure and CS-AKI. Twenty-seven neonates were included in model development. A 1-compartment model with bypass time as a covariate on clearance and volume of distribution best fit the data. Twenty-three neonates with caffeine exposure and 109 controls were included in the exposure-response analysis. Over half of neonates developed CS-AKI. On multivariable analysis, there were no significant differences between CS-AKI with and without caffeine exposure. Neonates with single-ventricle heart disease without CS-AKI had consistently higher simulated caffeine exposures. Our results highlight areas for further study to better understand disease- and bypass-specific effects on drug disposition and identify populations where caffeine may be beneficial.

Intraoperative and Postoperative Hemodynamic Predictors of Acute Kidney Injury in Pediatric Heart Transplant Recipients

Acute kidney injury (AKI) is common after pediatric heart transplantation (HT) and is associated with inferior patient outcomes. Hemodynamic risk factors for pediatric heart transplant recipients who experience AKI are not well described. We performed a retrospective review of 99 pediatric heart transplant patients at Lucile Packard Children's Hospital Stanford from January 1, 2015, to December 31, 2019, in which clinical and demographic characteristics, intraoperative perfusion data, and hemodynamic measurements in the first 48 postoperative hours were analyzed as risk factors for severe AKI (Kidney Disease: Improving Global Outcomes [KDIGO] stage ≥ 2). Univariate analysis was conducted using Fisher's exact test, Chi-square test, and the Wilcoxon rank-sum test, as appropriate. Multivariable analysis was conducted using logistic regression. Thirty-five patients (35%) experienced severe AKI which was associated with lower intraoperative cardiac index ( p  = 0.001), higher hematocrit ( p  < 0.001), lower body temperature ( p  < 0.001), lower renal near-infrared spectroscopy ( p  = 0.001), lower postoperative mean arterial blood pressure (MAP: p  = 0.001), and higher central venous pressure (CVP; p  < 0.001). In multivariable analysis, postoperative CVP >12 mm Hg (odds ratio [OR] = 4.27; 95% confidence interval [CI]: 1.48-12.3, p  = 0.007) and MAP <65 mm Hg (OR = 4.9; 95% CI: 1.07-22.5, p  = 0.04) were associated with early severe AKI. Children with severe AKI experienced longer ventilator, intensive care, and posttransplant hospital days and inferior survival ( p  = 0.01). Lower MAP and higher CVP are associated with severe AKI in pediatric HT recipients. Patients, who experienced AKI, experienced increased intensive care unit (ICU) morbidity and inferior survival. These data may guide the development of perioperative renal protective management strategies to reduce AKI incidence and improve patient outcomes.

Improved early risk stratification of deep sternal wound infection risk after coronary artery bypass grafting

BACKGROUND

Deep sternal wound infection (DSWI) following open heart surgery is associated with excessive morbidity and mortality. Contemporary DSWI risk prediction models aim at identifying high-risk patients with varying complexity and performance characteristics. We aimed to optimize the DSWI risk factor set and to identify additional risk factors for early postoperative detection of patients prone to DSWI.

METHODS

Single-centre retrospective analysis of patients with isolated multivessel coronary artery disease undergoing myocardial revascularization at Paracelsus Medical University Nuremberg between 2007 and 2022 was performed to identify risk factors for DSWI. Three data sets were created to examine preoperative, intraoperative, and early postoperative parameters, constituting the "Baseline", the "Improved Baseline" and the "Extended" models. The "Extended" data set included risk factors that had not been analysed before. Univariable and stepwise forward multiple logistic regression analyses were performed for each respective set of variables.

RESULTS

From 5221 patients, 179 (3.4%) developed DSWI. The "Extended" model performed best, with the area under the curve (AUC) of 0.80, 95%-CI: [0.76, 0.83]. Pleural effusion requiring intervention, postoperative delirium, preoperative hospital stay > 24 h, and the use of fibrin sealant were new independent predictors of DSWI in addition to age, Diabetes Mellitus on insulin, Body Mass Index, peripheral artery disease, mediastinal re-exploration, bilateral internal mammary harvesting, acute kidney injury and blood transfusions.

CONCLUSIONS

The "Extended" regression model with the short-term postoperative complications significantly improved DSWI risk discrimination after surgical revascularization. Short preoperative stay, prevention of postoperative delirium, protocols reducing the need for evacuation of effusion and restrictive use of fibrin sealant for sternal closure facilitate DSWI reduction.

TRIAL REGISTRATION

The registered retrospective study was registered at the study centre and approved by the Institutional Review Board of Paracelsus Medical University Nuremberg (IRB-2019-005).

Meaning and Management of Perioperative Oliguria

Perioperative oliguria is an alarm signal. The initial assessment includes closer patient monitoring, evaluation of volemic status, risk-benefit of fluid challenge or furosemide stress test, and investigation of possible perioperative complications.

Effect of preoperative moderate-dose statin and duration on acute kidney injury after cardiac surgery: a retrospective cohort study

BACKGROUND

The impact of preoperative statin use on postoperative acute kidney injury (AKI) is uncertain. We aimed to examine the association of statin therapy before cardiac surgery with postoperative AKI.

METHODS

The retrospective cohort study consisted of 1581 patients undergoing cardiac surgery. Postoperative AKI were identified by the modified KDIGO definition. Propensity-score matching was employed to control for selection bias, and logistic regression was used to control for confounders. Subgroup and interaction analyses were performed to evaluate the robustness of the findings.

RESULTS

The overall incidence of postoperative AKI and severe AKI were 42.19% and 12.27%, respectively. Preoperative moderate-dose statin was significantly associated with a reduced incidence of postoperative AKI (28.9% vs 43.0%, OR (95%CI): 0.54 (0.38, 0.77), p < 0.001) and severe AKI (6.9% vs 13.7%, OR (95%CI): 0.46 (0.26, 0.83), p = 0.009). The beneficial effect on postoperative AKI persisted after adjusting for major confounding factors (OR (95%CI): 0.47 (0.34, 0.66)). Decreased risk of postoperative AKI was observed in patients with preoperative statin duration of 7 ∼ 14 days (OR (95%CI): 0.41 (0.25, 0.65)) and over 14 days (OR (95%CI): 0.43 (0.28, 0.65)), but not in those with preoperative statin duration of <7 days. Similar favorable effects were noted in most subgroup patients, except for those with high-risk factors such as diabetes mellitus, previous congestive cardiac failure, arrhythmia, preoperative ACEI/ARB, aortic cross-clamping or IABP.

CONCLUSION

Preoperative moderate-dose statin was significantly related to a decreased risk of postoperative AKI, especially in patients who received statins for a longer duration. Further large-scale multicenter randomized controlled trials are needed to ascertain the impact of statin dose, duration, and timing on postoperative AKI in cardiac surgery patients.

A Novel Predictive Model for Acute Kidney Injury Following Surgery of the Aorta

Background

Acute kidney injury (AKI) frequently occurs after aortic surgery and has a significant impact on patient outcomes. Early detection or prediction of AKI is crucial for timely interventions. This study aims to develop and validate a novel model for predicting AKI following aortic surgery.

Methods

We enrolled 156 patients who underwent on-pump aortic surgery in our hospital from February 2023 to April 2023. Postoperative levels of eight cytokines related to macrophage polarization analyzed using a multiplex cytokine assay. All-subset regression was used to select the optimal cytokines to predict AKI. A logistic regression model incorporating the selected cytokines was used for internal validation in combination with a bootstrapping technique. The model's ability to discriminate between cases of AKI and non-AKI was assessed using receiver operating characteristic (ROC) curve analysis.

Results

Of the 156 patients, 109 (69.87%) developed postoperative AKI. Interferon-gamma (IFN- γ ) and interleukin-4 (IL-4) were identified as candidate AKI predictors. The cytokine-based model including IFN- γ and IL-4 demonstrated excellent discrimination (C-statistic: 0.90) and good calibration (Brier score: 0.11). A clinical nomogram was generated, and decision curve analysis revealed that the cytokine-based model outperformed the clinical factor-based model in terms of net benefit. Moreover, both IFN- γ and IL-4 emerged as independent risk factors for AKI. Patients in the second and third tertiles of IFN- γ and IL-4 concentrations had a significantly higher risk of severe AKI, a higher likelihood of requiring renal replacement therapy, or experiencing in-hospital death. These patients also had extended durations of mechanical ventilation and intensive care unit stays, compared with those in the first tertile (all p for group trend < 0.001).

Conclusions

We successfully established a novel and powerful predictive model for AKI, and demonstrating the significance of IFN- γ and IL-4 as valuable clinical markers. These cytokines not only predict the risk of AKI following aortic surgery but are also linked to adverse in-hospital outcomes. This model offers a promising avenue for the early identification of high-risk patients, potentially improving clinical decision-making and patient care.

Protein Kinase N1 Level Predicts Acute Kidney Injury in Patients Undergoing Cardiac Surgery: A Prospective Cohort Study

INTRODUCTION

The objective of this study was to examine the utility of protein kinase N1 (PKN1) as a biomarker of cardiac surgery-associated AKI (CSA-AKI).

METHODS

A prospective cohort study of 110 adults undergoing on-pump cardiac surgery was conducted. The associations between post-operative PKN1 and CSA-AKI, AKI severity, need for renal replacement therapy (RRT), duration of AKI, length of ICU stay, and post-operative hospital stay were evaluated.

RESULTS

Patients were categorized into three groups according to PKN1 tertiles. The incidence of CSA-AKI in the third tertile was 3.4-fold higher than that in the first. PKN1 was an independent risk factor for CSA-AKI. The discrimination of PKN1 to CSA-AKI assessed by ROC curve indicated that the AUC was 0.70, and the best cutoff was 5.025 ng/mL. This group (>5.025 ng/mL) was more likely to develop CSA-AKI (p < 0.001). The combined AUC of EuroSCORE, aortic cross-clamp time, and PKN1 was 0.82 (p < 0.001). A higher level of PKN1 was related to increased need for RRT, longer duration of AKI, and length of ICU and post-operative hospital stays.

CONCLUSIONS

PKN1 could be a potential biomarker for the prediction of CSA-AKI. The combination of PKN1, EuroSCORE, and aortic cross-clamp time was likely to predict the occurrence of CSA-AKI.

Perioperative Glycemic Management in Cardiac Surgery: A Narrative Review

Diabetes and hyperglycemic events in cardiac surgical patients are associated with postoperative morbidity and mortality. The causes of dysglycemia, the abnormal fluctuations in blood glucose concentrations, in the perioperative period include surgical stress, surgical techniques, medications administered perioperatively, and patient factors. Both hyperglycemia and hypoglycemia lead to poor outcomes after cardiac surgery. While trying to control blood glucose concentration tightly for better postoperative outcomes, hypoglycemia is the main adverse event. Currently, there is no definite consensus on the optimum perioperative blood glucose concentration to be maintained in cardiac surgical patients. This review provides an overview of perioperative glucose homeostasis, the pathophysiology of dysglycemia, factors that affect glycemic control in cardiac surgery, and current practices for glycemic control in cardiac surgery.

The Association Between Serum Glutathione Peroxidase-3 Concentration and Risk of Acute Kidney Injury After Cardiac Surgery: A Nested Case-Control Study

Oxidative stress has an integral role in the pathophysiology of cardiac surgery-associated acute kidney injury (CSA-AKI). Glutathione peroxidase 3 (GPx3) is an important antioxidant enzyme in circulation and is mainly secreted by the kidney. This study aimed to evaluate the relation between GPx3 protein and CSA-AKI. This study is a nested case-control study in Zhongshan Hospital affiliated with Fudan University. We examined serum samples from 80 CSA-AKI patients and 80 age- and gender-matched non-AKI patients who underwent cardiac surgery. AKI was defined according to Kidney Disease: Improving Global Outcomes (KDIGO) 2012 criteria. We measured serum GPx3 concentration using the enzyme-linked immunosorbent assay. GPx3 ratio is the ratio of preoperative and 6 hours postoperative of GPx3 protein concentration. We applied dose-response relation analyses to odds ratio in different GPx3 ratio levels and integrated it into the logistic model to predict the risk of AKI. The receiver operating characteristic curve and area under the curve (AUC) was used to assess the prediction models. Postoperative serum GPx3 concentrations were significantly lower in the AKI group compared with the non-AKI group (1.78 ± 0.33 vs 2.03 ± 0.27, p <0.001). Malondialdehyde was higher in the AKI than in the non-AKI group (17.74 ± 8.65 vs 7.48 ± 4.59, p <0.001). The AKI risk increased in a dose-dependent manner, which was flat in the first half of the GPx3 ratio and then tended to be faster. The peaking odds ratio of CSA-AKI was 2.615 at the GPx3 ratio of 1.21 to 1.40. The AUC value to predict CSA-AKI only included the GPx3 ratio was 72.3%. After gradually integrating other covariates (body mass index, aortic crossclamp time, and cardiopulmonary bypass), the model showed an AUC of 82.6%. The serum GPx3 concentration was significantly lower in the CSA-AKI group. GPx3 ratio has a good predictive value for CSA-AKI, which may be a potential early diagnostic marker for AKI.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Acute renal injury after aortic arch reconstruction with cardiopulmonary bypass for children: prediction models by machine learning of a retrospective cohort study

BACKGROUND

Acute renal injury (AKI) after aortic arch reconstruction with cardiopulmonary bypass leads to injury of multiple organs and increases perioperative mortality. The study was performed to explore risk factors for AKI. We aim to develop a prediction model that can be used to accurately predict AKI through machine learning (ML).

METHODS

A retrospective analysis was performed on 134 patients with aortic arch reconstruction with cardiopulmonary bypass who were treated at our hospital from January 2002 to January 2022. Risk factors for AKI were compositive and were evaluated with comprehensive analyses. Six artificial intelligence (AI) models were used for machine learning to build prediction models and to screen out the best model to predict AKI.

RESULTS

Weight, eGFR, cyanosis, PDA, newborn birth and duration of renal ischemia were closely related to AKI. By integrating the results of the training cohort and validation cohort, we finally confirmed that the logistic regression model was the most stable model among all the models, and the logistic regression model showed good discrimination, calibration and clinical practicability. Based on 6 independent factors, the dynamic nomogram can be used as a predictive tool for clinical application.

CONCLUSIONS

DHCA could be considered in aortic arch reconstruction if additional perfusion of lower body were not performed especially when renal ischemia is greater than 30 min. Machine Learning models should be developed for early recognition of AKI.

TRIAL REGISTRATION

ChiCTR, ChiCTR2200060552. Registered 4 june 2022.

Interpretable machine learning models for early prediction of acute kidney injury after cardiac surgery

OBJECTIVE

Postoperative acute kidney injury (PO-AKI) is a common complication after cardiac surgery. We aimed to evaluate whether machine learning algorithms could significantly improve the risk prediction of PO-AKI.

METHODS

The retrospective cohort study included 2310 adult patients undergoing cardiac surgery in a tertiary teaching hospital, China. Postoperative AKI and severe AKI were identified by the modified KDIGO definition. The sample was randomly divided into a derivation set and a validation set based on a ratio of 4:1. Exploiting conventional logistic regression (LR) and five ML algorithms including decision tree, random forest, gradient boosting classifier (GBC), Gaussian Naive Bayes and multilayer perceptron, we developed and validated the prediction models of PO-AKI. We implemented the interpretation of models using SHapley Additive exPlanation (SHAP) analysis.

RESULTS

Postoperative AKI and severe AKI occurred in 1020 (44.2%) and 286 (12.4%) patients, respectively. Compared with the five ML models, LR model for PO-AKI exhibited the largest AUC (0.812, 95%CI: 0.756, 0.860, all P < 0.05), sensitivity (0.774, 95%CI: 0.719, 0.813), accuracy (0.753, 95%CI: 0.719, 0.781) and Youden index (0.513, 95%CI: 0.451, 0.573). Regarding severe AKI, GBC algorithm showed a significantly higher AUC than the other four ML models (all P < 0.05). Although no significant difference (P = 0.173) was observed in AUCs between GBC (0.86, 95%CI: 0.808, 0.902) and conventional logistic regression (0.803, 95%CI: 0.746, 0.852), GBC achieved greater sensitivity, accuracy and Youden index than conventional LR. Notably, SHAP analyses showed that preoperative serum creatinine, hyperlipidemia, lipid-lowering agents and assisted ventilation time were consistently among the top five important predictors for both postoperative AKI and severe AKI.

CONCLUSION

Logistic regression and GBC algorithm demonstrated moderate to good discrimination and superior performance in predicting PO-AKI and severe AKI, respectively. Interpretation of the models identified the key contributors to the predictions, which could potentially inform clinical interventions.

Postoperative acute kidney injury after thoracic endovascular aortic repair for acute type B aortic dissection

BACKGROUND

Thoracic endovascular aortic repair (TEVAR) has evolved as the standard for treating complicated acute type B aortic dissection (ATBAD). Acute kidney injury (AKI) is a common complication in critically ill patients and is commonly observed in patients with ATBAD. The purpose of the study was to characterize AKI after TEVAR.

METHODS

All patients who underwent TEVAR for ATBAD from 2011 through 2021 were identified using the International Registry of Acute Aortic Dissection. The primary end point was AKI. A generalized linear model analysis was performed to identify a factor associated with postoperative AKI.

RESULTS

A total of 630 patients presented with ATBAD and underwent TEVAR. The indication for TEVAR was complicated ATBAD in 64.3%, high-risk uncomplicated ATBAD in 27.6%, and uncomplicated ATBAD in 8.1%. Of 630 patients, 102 (16.2%) developed postoperative AKI (AKI group) and 528 patients (83.8%) did not (non-AKI group). The most common indication for TEVAR was malperfusion (37.5%). In-hospital mortality was significantly higher in the AKI group (18.6% vs 4%; P < .001). Postoperatively, cerebrovascular accident, spinal cord ischemia, limb ischemia, and prolonged ventilation were more commonly observed in the AKI group. The expected mortality was similar at 2 years between the two groups (P = .51). Overall, the preoperative AKI was observed in 95 (15.7%) in the entire cohort consisting of 60 (64.5%) in the AKI group and 35 (6.8%) in the non-AKI group. A history of CKD (odds ratio, 4.6; 95% confidence interval, 1.5-14.1; P = .01) and preoperative AKI (odds ratio, 24.1; 95% confidence interval, 10.6-55.0; P < .001) were independently associated with postoperative AKI.

CONCLUSIONS

The incidence of postoperative AKI was 16.2% in patients undergoing TEVAR for ATBAD. Patients with postoperative AKI had a higher rate of in-hospital morbidities and mortality than those without. A history of CKD and preoperative AKI were independently associated with postoperative AKI.

Association of intraoperative cerebral and somatic tissue oxygen saturation with postoperative acute kidney injury in adult patients undergoing multiple valve surgery

BACKGROUND

The association between tissue oxygenation with postoperative acute kidney injury (AKI) in adult patients undergoing multiple valve surgery has not been specifically studied.

METHODS

In this prospective exploratory cohort study, 99 patients were enrolled. The left forehead, the left forearm, the left upper thigh, and the left renal region tissue oxygen saturation using near-infrared spectroscopy were monitored. The association between each threshold and AKI was assessed. The relative and absolute thresholds were < 70%, < 75%, < 80%, < 85%, < 90%, < 95%, and < 100% baseline, and baseline-standard deviation (SD), -1.5 SD, -2 SD, -2.5 SD, and -3 SD. Multivariate logistic regression analysis was adopted to explore the association.

RESULTS

AKI occurred in 53 (54%) patients. The absolute value-based SrrO2 thresholds associated with AKI were baseline-3 SD (odds ratio [OR], 4.629; 95% confidence interval [CI], 1.238-17.314; P = 0.023) and baseline-2.5 SD (OR, 2.842; 95% CI, 1.025-7.881; P = 0.045) after adjusting for the potential confounders, those are renal region tissue oxygen saturation of 55% and 60%, but not statistically significant after correcting for multiple testing (corrected P = 0.114 and 0.179, respectively).

CONCLUSION

The SrrO2 desaturation, defined as < baseline - 2.5 SD or < baseline - 3 SD, may be associated with AKI. The thresholds need to be verified in future large-scale studies.

TRIAL REGISTRATIONS

The study was registered at ClinicalTrials.gov, first trial registration: 26/10/2017, identifier: NCT03323203.

Kidney Injury after Cardiac Surgery: Prevention-Associated Cost Reduction

INTRODUCTION

Cardiac surgery may induce acute kidney injury and the need for renal replacement therapy. It is also associated with higher hospital costs, morbidity and mortality. The aims of this study were to investigate predictors of cardiac surgery associated acute kidney injury in our population and to determine the burden of acute kidney injury in elective cardiac surgery, evaluating the potential cost effectiveness of preventing it through the application of the Kidney Disease: Improving Global Outcomes bundle of care to high-risk patient groups identified by the [TIMP-2]x[IGFBP7] used as a screening test.

MATERIAL AND METHODS

In a University Hospital single-center retrospective cohort study we analyzed a consecutive sample of adults who underwent elective cardiac surgery between January and March 2015. A total of 276 patients were admitted during the study period. Data from all patients was analyzed until hospital discharge or the patient's death. The economic analysis was performed from the hospital costs' perspective.

RESULTS

Cardiac surgery associated acute kidney injury occurred in 86 patients (31%). After adjustment, higher preoperative serum creatinine (mg/L, ORadj = 1.09; 95% CI: 1.01 - 1.17), lower preoperative hemoglobin (g/dL, ORadj = 0.79; 95% CI: 0.67 - 0.94), chronic systemic hypertension (ORadj = 5.00; 95% CI: 1.67 - 15.02), an increase in cardiopulmonary bypass time (min, ORadj = 1.01; 95% CI: 1.00 - 1.01) and perioperative use of sodium nitroprusside (ORadj = 6.33; 95% CI: 1.80 - 22.28) remained significantly associated with cardiac surgery related acute kidney injury. The expected cumulative surplus cost for the hospital linked with cardiac surgery associated acute kidney injury (86 patients) was €120 695.84. Based on a median absolute risk reduction of 16.6%, by dosing kidney damage biomarkers in every patient and using preventive measures in high-risk patients, we would expect a break-even point upon screening 78 patients, which would translate, in our patient cohort, into an overall cost benefit of €7145.

CONCLUSION

Preoperative hemoglobin, serum creatinine, systemic hypertension, cardiopulmonary bypass time and perioperative use of sodium nitroprusside were independent predictors of cardiac surgery associated acute kidney injury. Our cost-effectiveness modelling suggests that the use of kidney structural damage biomarkers combined with an early prevention strategy could be associated with potential cost savings.

Serum Insulin-Like Growth Factor-Binding Protein 7 Deriving from Spleen and Lung Could Be Used for Early Recognition of Cardiac Surgery-Associated Acute Kidney Injury

INTRODUCTION

The utility of arithmetic product of urinary tissue metalloproteinase inhibitor 2 (TIMP2) and insulin-like growth factor-binding protein 7 (IGFBP7) concentrations has been widely accepted on early diagnosis of acute kidney injury (AKI). However, which organ is the main source of those two factors and how the concentration of IGFBP7 and TIMP2 changed in serum during AKI still remain to be defined.

METHODS

In mice, gene transcription and protein levels of IGFBP7/TIMP2 in the heart, liver, spleen, lung, and kidney were measured in both ischemia-reperfusion injury (IRI)- and cisplatin-induced AKI models. Serum IGFBP7 and TIMP2 levels were measured and compared in patients before cardiac surgery and at inclusion (0 h), 2 h, 6 h, and 12 h after intensive care unit (ICU) admission, and compared with serum creatinine (SCr), blood urea nitrogen (BUN), estimated glomerular filtration rate (eGFR), and serum uric acid (UA).

RESULTS

In mouse IRI-AKI model, compared with the sham group, the expression levels of IGFBP7 and TIMP2 did not change in the kidney, but significantly upregulated in the spleen and lung. Compared with patients who did not develop AKI, the concentration of serum IGFBP7 at as early as 2 h after ICU admission (sIGFBP7-2 h) was significantly higher in patients who developed AKI. The relationships between sIGFBP7-2 h in AKI patients and log2 (SCr), log2 (BUN), log2 (eGFR), and log2 (UA) were statistically significant. The diagnostic performance of sIGFBP7-2 h measured by the macro-averaged area under the receiver operating characteristic curve was 0.948 (95% CI, 0.853-1.000; p < 0.001).

CONCLUSION

The spleen and lung might be the main source of serum IGFBP7 and TIMP2 during AKI. The serum IGFBP7 value demonstrated good predictive accuracy for AKI following cardiac surgery within 2 h after ICU admission.

DNA binding protein YB-1 is a part of the neutrophil extracellular trap mediation of kidney damage and cross-organ effects

Open-heart surgery is associated with high morbidity, with acute kidney injury (AKI) being one of the most commonly observed postoperative complications. Following open-heart surgery, in an observational study we found significantly higher numbers of blood neutrophils in a group of 13 patients with AKI compared to 25 patients without AKI (AKI: 12.9±5.4 ×109 cells/L; non-AKI: 10.1±2. 9 ×109 cells/L). Elevated serum levels of neutrophil extracellular trap (NETs) components, such as dsDNA, histone 3, and DNA binding protein Y-box protein (YB)-1, were found within the first 24 hours in patients who later developed AKI. We could demonstrate that NET formation and hypoxia triggered the release of YB-1, which was subsequently shown to act as a mediator of kidney tubular damage. Experimentally, in two models of AKI mimicking kidney hypoperfusion during cardiac surgery (bilateral ischemia/reperfusion (I/R) and systemic lipopolysaccharide (LPS) administration), a neutralizing YB-1 antibody was administered to mice. In both models, prophylactic YB-1 antibody administration significantly reduced the tubular damage (damage score range 1-4, the LPS model: non-specific IgG control, 0.92±0.23; anti-YB-1 0.65±0.18; and in the I/R model: non-specific IgG control 2.42±0.23; anti-YB-1 1.86±0.44). Even in a therapeutic, delayed treatment model, antagonism of YB-1 ameliorated AKI (damage score, non-specific IgG control 3.03±0.31; anti-YB-1 2.58±0.18). Thus, blocking extracellular YB-1 reduced the effects induced by hypoxia and NET formation in the kidney and significantly limited AKI, suggesting that YB-1 is part of the NET formation process and an integral mediator of cross-organ effects.