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

A crucial role of miR-155 in the pathomechanism of acute kidney injury

Acute kidney injury (AKI) is one of the nonnegligible causes of mortality worldwide. It is important to understand the underlying molecular mechanism of AKI to effective therapeutic targets. miR-155 has been found to play a pivotal role in the development of AKI, while a comprehensive review on this topic is currently still lacking. Based on this review, we found that miR-155and is strongly correlated with the pathophysiological development of AKI by modulating cell apoptosis, inflammation, and proliferation. Mechanistically, miR-155 exerts a promoting function in multiple types of AKI by regulating multiple proteins or signaling pathways, such as SOCS-1, ERRFI1, SOCS-1, TRF1, CDK12, and TCF4/Wnt/β-catenin pathway. The inhibition of miR-155 has a renoprotective effect in drug- or substance-induced AKI. Therefore, drugs or biological compounds targeted by miR-155 and its pathways may recover the process of AKI by altering apoptosis, inflammation, and pyroptosis. A miRNA nanocarrier system that has already been developed could offer a novel approach to treat AKI, providing a direction for future research. Further large-scale studies are necessary to elucidate the clinical significance of miR-155 as a potential therapeutic target for multiple types of AKI.

Elevated postoperative systemic immune-inflammation index associates with acute kidney injury after cardiac surgery: a large-scale cohort study

Objective

To investigate whether postoperative systemic immune-inflammation index (SII) is associated with acute kidney injury (AKI) after cardiac surgery.

Methods

We included patients undergoing cardiac surgery from the Medical Information Mart for Intensive Care-Ⅳ database to conduct a retrospective cohort study. The outcomes are AKI, severe AKI, and 30-day mortality after cardiac surgery. Analytical techniques including receiver operating characteristic (ROC) analysis, restricted cubic splines (RCS), and multivariable logistic regression were used to assess the association between SII and outcomes. Sensitivity analyses using inverse probability of treatment weighting (IPTW) and the E-value were conducted to validate the stability of the results.

Results

3,799 subjects were included in this study. We used ROC to calculate an optimal cutoff value for predicting AKI after cardiac surgery, and subsequently patients were divided into two groups based on the cutoff value (Low SII: ≤ 949 × 109/L; High SII: > 949 × 109/L). ROC showed moderately good performance of SII for predicting AKI, while RCS also indicated a positive association between SII and AKI. The multivariate logistic analysis further affirmed the heightened risk of AKI in patients in the high SII group (OR, 5.33; 95%CI, 4.34-6.53; P < 0.001). Similar associations were observed between SII and severe AKI. Sensitivity and subgroup analyses indicated the robustness of the findings.

Conclusion

Elevated SII was independently associated with a higher risk of AKI in adults undergoing cardiac surgery. The potential causal relationship between postoperative SII and cardiac surgery associated AKI warrants prospective research.

Clinical Utility of LC-MS/MS for Blood Myo-Inositol in Patients with Acute Kidney Injury and Chronic Kidney Disease

BACKGROUND

Diagnosing acute kidney injury (AKI) and chronic kidney disease (CKD) relies on creatinine, which lacks optimal diagnostic sensitivity. The kidney-specific proximal tubular enzyme myo-inositol oxygenase (MIOX) catalyzes the conversion of myo-inositol (MI) to D-glucuronic acid. We hypothesized that proximal tubular damage, which occurs in AKI and CKD, will decrease MIOX activity, causing MI accumulation. To explore this, we developed an LC-MS/MS assay to quantify plasma MI and assessed its potential in identifying AKI and CKD patients.

METHODS

MI was quantified in plasma from 3 patient cohorts [normal kidney function (n = 105), CKD (n = 94), and AKI (n = 54)]. The correlations between MI and creatinine were determined using Deming regression and Pearson correlation and the impact of age, sex, and ethnicity on MI concentrations was assessed. Receiver operating characteristic curve analysis was employed to evaluate MI diagnostic performance.

RESULTS

In volunteers with normal kidney function, the central 95th percentile range of plasma MI concentrations was 16.6 to 44.2 µM. Age, ethnicity, and sex showed minimal influence on MI. Patients with AKI and CKD exhibited higher median MI concentrations [71.1 (25th percentile: 38.2, 75th percentile: 115.4) and 102.4 (77, 139.5) µM], respectively. MI exhibited excellent sensitivity (98.9%) and specificity (100%) for diagnosing CKD. In patients with AKI, MI increased 32.9 (SD 16.8) h before creatinine.

CONCLUSIONS

This study unveils MI as a potential renal biomarker, notably elevated in plasma during AKI and CKD. Plasma MI rises 33 h prior to serum creatinine, enabling early AKI detection. Further validation and exploration of MI quantitation in kidney disease diagnosis is warranted.

Averaged versus Persistent Reduction in Urine Output to Define Oliguria in Critically Ill Patients: An Observational Study

Key Points

When assessing urine output, consideration of an average or persistent value below a threshold has important diagnostic and prognostic implications Seventy-three percent (95% confidence interval, 72.3 to 73.7) of patients had oliguria by the average method versus 54.3% (53.5 to 55.1) by the persistent method.

Background

Oliguria is defined as a urine output (UO) of <0.5 ml/kg per hour over 6 hours. There is no consensus as per whether an average or persistent value should be considered.

Methods

We analyzed all adults admitted to a tertiary intensive care unit between 2010 and 2020, except those on chronic dialysis or who declined consent. We extracted hourly UO and, across 6-hour sliding time windows, assessed for the presence of oliguria according to the average (mean UO below threshold) and persistent (all measurements below a threshold) methods. For both methods, we compared oliguria's incidence and association with 90-day mortality and acute kidney disease at hospital discharge.

Results

Among 15,253 patients, the average method identified oliguria more often than the persistent method (73% [95% confidence interval, 72.3 to 73.7] versus 54.3% [53.5 to 55.1]). It displayed a higher sensitivity for the prediction of 90-day mortality (85% [83.6 to 86.4] versus 70.3% [68.5 to 72]) and acute kidney disease at hospital discharge (85.6% [84.2 to 87] versus 71.8% [70 to 73.6]). However, its specificity was lower for both outcomes (29.8% [28.9 to 30.6] versus 49.4% [48.5 to 50.3] and 29.8% [29 to 30.7] versus 49.8% [48.9 to 50.7]). After adjusting for illness severity, comorbidities, age, admission year, weight, sex, and AKI on admission, the absolute difference in mortality attributable to oliguria at the population level was similar with both methods (5%). Similar results were obtained when analyses were restricted to patients without AKI on admission, with documented body weight, with presence of indwelling catheter throughout stay, and who did not receive KRT or diuretics.

Conclusions

The assessment method of oliguria has major diagnostic and prognostic implications. Its definition should be standardized.

[Biomarkers of oxidative stress and inflammation in contrast-associated acute kidney injury]

BACKGROUND

Iodinated contrast-induced acute kidney injury (CI-AKI) is a common cause of renal failure, especially in patients with risk factors. This study analyses different renal biomarkers in patients undergoing computed tomography scans with iodinated contrast to identify the molecular and cellular mechanisms involved in the pathogenesis of CI-AKI.

METHODOLOGY

Prospective study that included patients with high risk of renal disease who received iodinated contrast (iohexol) for the computed tomography scans. Functional biomarkers (creatinine and cystatin C), inflammatory and oxidative stress markers (neutrophil gelatinase-associated lipocalin [NGAL], interleukin-8 [IL-8], superoxide dismutase [SOD], F2-isoprostanes, and cardiotrophin-1), and cell cycle biomarkers (Nephrocheck®) were analysed before the iodinated contrast and 4, 12, 24, and 48 hours post-contrast, in relation to the incidence of IC-AKI.

RESULTS

IC-AKI was observed in 30.6% of the 62 study participants and in 57.1% of the patients with diabetes and renal dysfunction. Factors associated with IC-AKI were a higher mean age (74.4 vs 64.9 years), pre-existing renal dysfunction (60 vs 16.7%), and higher adjusted mean volume of iohexol (42.9 vs 32.1%). As for non-functional biomarkers. No differences were found between patients with and without CI-AKI. The use of iodinated contrast was associated with a decrease in SOD antioxidant activity at 4 hours and an increase in IL-8 at 12 hours post-administration of the iodinated contrast.

CONCLUSIONS

Administration of iohexol in computed tomography scans in patients with high risk of renal disease results in an elevated percentage of CI-AKI, attributable to ischemia/reperfusion injury and/or direct toxicity of the iodinated contrast.

An overview of circulating and urinary biomarkers capable of predicting the transition of acute kidney injury to chronic kidney disease

INTRODUCTION

Acute kidney injury (AKI) defined by a substantial decrease in kidney function within hours to days and is often irreversible with higher risk to chronic kidney disease (CKD) transition.

AREAS COVERED

The authors discuss the diagnostic and predictive utilities of serum and urinary biomarkers on AKI and on the risk of AKI-to-CKD progression. The authors focus on the relevant literature covering evidence of circulating and urinary biomarkers' capability to predict the transition of AKI to CKD.

EXPERT OPINION

Based on the different modalities of serum and urinary biomarkers, multiple biomarker panel seems to be potentially useful to distinguish between various types of AKI, to detect the severity and the risk of AKI progression, to predict the clinical outcome and evaluate response to the therapy. Serum/urinary neutrophil gelatinase-associated lipocalin (NGAL), serum/urinary uromodulin, serum extracellular high mobility group box-1 (HMGB-1), serum cystatin C and urinary liver-type fatty acid-binding protein (L-FABP) were the most effective in the prediction of AKI-to-CKD transition regardless of etiology and the presence of critical state in patients. The current clinical evidence on the risk assessments of AKI progression is mainly based on the utility of combination of functional, injury and stress biomarkers, mainly NGAL, L-FABP, HMGB-1 and cystatin C.

Ultrasound molecular imaging for early detection of acute renal ischemia-reperfusion injury

Background

Microcirculatory perfusion disorder and inflammatory response are critical links in acute kidney injury (AKI). We aim to construct anti-vascular cell adhesion molecule-1(VCAM-1) targeted microbubbles (TM) to monitor renal microcirculatory perfusion and inflammatory response.

Methods

TM carrying VCAM-1 polypeptide was constructed by biological coupling. The binding ability of TM to human umbilical vein endothelial cells (HUVECs) was detected. Bilateral renal ischemia-reperfusion injury (IRI) models of mice were established to evaluate microcirculatory perfusion and inflammatory response using TM. Thirty-six mice were randomly divided into six groups according to the different reperfusion time (0.5, 2, 6, 12, and 24 h) and sham-operated group (Sham group). The correlation of TM imaging with serum and histopathological biomarkers was investigated.

Results

TM has advantages such as uniform distribution, regular shape, high stability, and good biosafety. TM could bind specifically to VCAM-1 molecule expressed by tumor necrosis factor-alpha (TNF-α)-treated HUVECs. In the renal IRI-AKI model, the area under the curve (AUC) of TM significantly decreased both in the renal cortical and medullary after 2 h of reperfusion compared with the Sham group (p < 0.05). Normalized intensity difference (NID) of TM at different reperfusion time was all higher than that of blank microbubbles (BM) and the Sham group (p < 0.05). Ultrasound molecular imaging of TM could detect AKI early before commonly used renal function markers, histopathological biomarkers, and BM imaging. AUC of TM was negatively correlated with serum creatinine (Scr), blood urea nitrogen (BUN), and Cystatin C (Cys-C) levels, and NID of TM was linearly correlated with VCAM-1, TNF-α, and interleukin-6 (IL-6) expression (p < 0.05).

Conclusions

Ultrasound molecular imaging based on TM carrying VCAM-1 polypeptide can accurately evaluate the changes in renal microcirculatory perfusion and inflammatory response, which might be a promising modality for early diagnosis of AKI.

Clinical Profile and Short-Term Outcomes of Acute Kidney Injury in Elderly Patients in a Tertiary Care Center

Background Acute kidney injury (AKI) is a common and serious condition affecting elderly patients. Despite its significance, comprehensive research focusing specifically on the clinical profile and short-term outcomes of AKI in this vulnerable population is lacking. Objective This study aimed to evaluate the clinical profile and short-term outcomes of AKI in elderly patients admitted to a tertiary care center. Methods A prospective observational study was conducted from December 2023 to March 2024, involving 75 elderly patients (aged ≥65 years) diagnosed with AKI. Baseline demographic data, clinical profiles, laboratory investigations, mortality rate among elderly patients diagnosed with AKI within 30 days of diagnosis, and short-term outcomes were recorded and analyzed. Descriptive statistics and appropriate statistical tests were used for the data analysis. Results The study cohort had a mean age of 72.6 years. Hypertension was present in 55 patients (73.3%), and diabetes mellitus was observed in 30 patients (40.0%). Prerenal causes of AKI were identified in 40 patients (53.3%), while acute tubular necrosis was found in 25 patients (33.3%). Stage 2 AKI was the most common, affecting 35 patients (46.7%). Out of the 75 patients, 15 patients (20.0%) succumbed to AKI within the study period. Deceased patients had longer hospital stays, with a median of 16 days compared to 10 days for survivors. ICU admission was required for 13 of the deceased patients (86.7%), compared to 32 of the surviving patients (53.3%). The need for renal replacement therapy was higher among the deceased patients, with 11 out of 15 patients (73.3%) requiring it, compared to 19 out of 60 surviving patients (31.7%). Renal function recovery was notably lower in the deceased patients. Conclusion AKI in elderly patients was associated with significant morbidity and mortality, highlighting the need for early recognition, appropriate management, and preventive strategies. A comprehensive evaluation of the clinical profile and short-term outcomes of AKI in the elderly population provides valuable insights for optimizing patient care and improving outcomes.

Recent Update on Acute Kidney Injury-to-Chronic Kidney Disease Transition

Acute kidney injury (AKI) is characterized by an abrupt decline of excretory kidney function. The incidence of AKI has increased in the past decades. Patients diagnosed with AKI often undergo diverse clinical trajectories, such as early or late recovery, relapses, and even a potential transition from AKI to chronic kidney disease (CKD). Although recent clinical studies have demonstrated a strong association between AKI and progression of CKD, our understanding of the complex relationship between AKI and CKD is still evolving. No cohort study has succeeded in painting a comprehensive picture of these multi-faceted pathways. To address this lack of understanding, the idea of acute kidney disease (AKD) has recently been proposed. This presents a new perspective to pinpoint a period of heightened vulnerability following AKI, during which a patient could witness a substantial decline in glomerular filtration rate, ultimately leading to CKD transition. Although AKI is included in a range of kidney conditions collectively known as AKD, spanning from mild and self-limiting to severe and persistent, AKD can also occur without a rapid onset usually seen in AKI, such as when kidney dysfunction slowly evolves. In the present review, we summarize the most recent findings about AKD, explore the current state of biomarker discovery related to AKD, discuss the latest insights into pathophysiological underpinnings of AKI to CKD transition, and reflect on therapeutic challenges and opportunities that lie ahead.

Characterization of macrophages in ischemia-reperfusion injury-induced acute kidney injury based on single-cell RNA-Seq and bulk RNA-Seq analysis

Acute kidney injury (AKI) is a complex disease, with macrophages playing a vital role in its progression. However, the mechanism of macrophage function remains unclear and strategies targeting macrophages in AKI are controversial. To address this issue, we used single-cell RNA-seq analysis to identify macrophage sub-types involved in ischemia-reperfusion-induced AKI, and then screened for associated hub genes using intersecting bulk RNA-seq data. The single-cell and bulk RNA-seq datasets were obtained from the Gene Expression Omnibus (GEO) database. Screening of differentially-expressed genes (DEGs) and pseudo-bulk DEG analyses were used to identify common hub genes. Pseudotime and trajectory analyses were performed to investigate the progression of cell differentiation. CellChat analysis was performed to reveal the crosstalk between cell clusters. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were used to identify enriched pathways in the cell clusters. Immunofluorescence and RT-PCR were preformed to validate the expression of the identified hub genes. Four hub genes, Vim, S100a6, Ier3, and Ccr1, were identified in the infiltrated macrophages between normal samples and those 3 days after ischemia-reperfusion renal injury (IRI); all were associated with the progression of IRI-induced AKI. Increased expression of Vim, S100a6, Ier3, and Ccr1 in infiltrated macrophages may be associated with inflammatory responses and may mediate crosstalk between macrophages and renal tubular epithelial cells under IRI conditions. Our results reveal that Ier3 may be critical in AKI, and that Vim, S100a6, Ier3, and Ccr1 may act as novel biomarkers and potential therapeutic targets for IRI-induced AKI.

Pattern and prognostic factors for kidney function progression in survivors of children with acute kidney injury: a cohort study

OBJECTIVE

To examine the pattern of kidney function progression after acute kidney injury (AKI) and identify the associated risk factors.

DESIGN

A prospective cohort study was conducted from June 2020 to June 2021 on children aged 1 month to <18 years admitted to the paediatric intensive care unit (PICU). Acute kidney disease (AKD) was defined as AKI persisting from 7 to 90 days after diagnosis. The natural history and prognostic factors of kidney function progression were determined.

RESULTS

Among the 253 admissions with a median (IQR) age of 4.9 (9.7) years, the AKI and AKD incidence was 41.9% and 52.2% respectively. The incidence of estimated glomerular filtration rate (eGFR) <90 mL/min/1.73 m2 was 6.7% at 90 days and 11.9% at latest follow-up. Severe and prolonged AKI and higher degree of nephrotoxic medication exposure were associated with AKD development. The severity and duration of AKI and AKD significantly predicted kidney function non-recovery. Children with both entities exhibited a higher peak-to-baseline serum creatinine level ratio at 90 days (1.6 vs 1.0, p<0.001), and a more pronounced decline in eGFR (21% vs 19%, p=0.028) during the follow-up period compared with those without AKI/AKD. They also had an increased risk of having eGFR <90 mL/min/1.73 m2 at 90 days (HR 14.9 (95% CI 1.8 to 124.0)) and latest follow-up (HR 3.8 (95% CI 1.1 to 13.1)).

CONCLUSIONS

AKI and AKD are prevalent among critically ill children and pose substantial risk for non-recovery of kidney function among PICU survivors. A structural follow-up visit for AKI survivors to monitor kidney function progression is advocated.

The therapeutic effect of Picroside II in renal ischemia-reperfusion induced acute kidney injury: An experimental study

The microcirculation hemodynamics change and inflammatory response are the two main pathophysiological mechanisms of renal ischemia-reperfusion injury (IRI) induced acute kidney injury (AKI). The treatment of microcirculation hemodynamics and inflammatory response can effectively alleviate renal injury and correct renal function. Picroside II (P II) has a wide range of pharmacological effects. Still, there are few studies on protecting IRI-AKI, and whether P II can improve renal microcirculation perfusion is still being determined. This study aims to explore the protective effect of P II on IRI-AKI and evaluate its ability to enhance renal microcirculation perfusion. In this study, a bilateral renal IRI-AKI model in mice was established, and the changes in renal microcirculation and inflammatory response were quantitatively evaluated before and after P II intervention by contrast-enhanced ultrasound (CEUS). At the same time, serum and tissue markers were measured to assess the changes in renal function. The results showed that after P II intervention, the levels of serum creatinine (Scr), blood urea nitrogen (BUN), serum cystatin C (Cys-C), kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), malondialdehyde (MDA), and superoxide dismutase (SOD), as well as the time-to-peak (TTP), peak intensity (PI) and area under the curve (AUC), and the normalized intensity difference (NID) were all alleviated. In conclusion, P II can improve renal microcirculation perfusion changes caused by IRI-AKI, reduce inflammatory reactions during AKI, and enhance renal antioxidant stress capacity. P II may be a new and promising drug for treating IRI-AKI.

Endothelium-related biomarkers enhanced prediction of kidney support therapy in critically ill patients with non-oliguric acute kidney injury

Acute kidney injury (AKI) is a common condition in hospitalized patients who often requires kidney support therapy (KST). However, predicting the need for KST in critically ill patients remains challenging. This study aimed to analyze endothelium-related biomarkers as predictors of KST need in critically ill patients with stage 2 AKI. A prospective observational study was conducted on 127 adult ICU patients with stage 2 AKI by serum creatinine only. Endothelium-related biomarkers, including vascular cell adhesion protein-1 (VCAM-1), angiopoietin (AGPT) 1 and 2, and syndecan-1, were measured. Clinical parameters and outcomes were recorded. Logistic regression models, receiver operating characteristic (ROC) curves, continuous net reclassification improvement (NRI) and integrated discrimination improvement (IDI) were used for analysis. Among the patients, 22 (17.2%) required KST within 72 h. AGPT2 and syndecan-1 levels were significantly greater in patients who progressed to the KST. Multivariate analysis revealed that AGPT2 and syndecan-1 were independently associated with the need for KST. The area under the ROC curve (AUC-ROC) for AGPT2 and syndecan-1 performed better than did the constructed clinical model in predicting KST. The combination of AGPT2 and syndecan-1 improved the discrimination capacity of predicting KST beyond that of the clinical model alone. Additionally, this combination improved the classification accuracy of the NRI and IDI. AGPT2 and syndecan-1 demonstrated predictive value for the need for KST in critically ill patients with stage 2 AKI. The combination of AGPT2 and syndecan-1 alone enhanced the predictive capacity of predicting KST beyond clinical variables alone. These findings may contribute to the early identification of patients who will benefit from KST and aid in the management of AKI in critically ill patients.

Review of the limitations of current biomarkers in acute kidney injury clinical practices

Acute kidney injury is a prevalent disease in hospitalized patients and is continuously increasing worldwide. Various efforts have been made to define and classify acute kidney injury to understand the progression of this disease. Furthermore, deviations from structure and kidney function and the current diagnostic guidelines are not adequately placed due to baseline serum creatinine values, which are rarely known and estimated based on glomerular function rate, resulting in misclassification of acute kidney injury staging. Hence, the current guidelines are still developing to improve and understand the clinical implications of risk factors and earlier predictive biomarkers of acute kidney injury. Yet, studies have indicated disadvantages and limitations with the current acute kidney injury biomarkers, including lack of sensitivity and specificity. Therefore, the present narrative review brings together the most current evidenced-based practice and literature associated with the limitations of the gold standard for acute kidney injury diagnoses, the need for novel acute kidney injury biomarkers, and the process for biomarkers to be qualified for diagnostic use under the following sections and themes. The introduction section situates the anatomy and normal and abnormal kidney functions related to acute kidney injury disorders. Guidelines in providing acute kidney injury definitions and classification are then considered, followed by a discussion of the disadvantages of standard markers used to diagnose acute kidney injury. Characteristics of an ideal acute kidney injury biomarker are discussed concerning sensitivity, specificity, and anatomic location of injury. A particular focus on the role and function of emerging biomarkers is discussed in relation to their applications and significance to the prognosis and severity of acute kidney injury. Findings show emerging markers are early indicators of acute kidney injury prediction in different clinical settings. Finally, the process required for a biomarker to be applied for diagnostic use is explained.

Lasmiditan restores mitochondrial quality control mechanisms and accelerates renal recovery after ischemia-reperfusion injury

BACKGROUND

Mitochondrial dysfunction is a well-established result of acute kidney injury (AKI). Previously, we identified that 5-hydroxytryptamine 1F (5-HT1F) receptor agonism with lasmiditan induces mitochondrial biogenesis (MB) and improves renal vasculature and function in an AKI mouse model. We hypothesize that lasmiditan also modulates mitochondrial dynamics and mitophagy in a mouse model of AKI.

METHODS

Male mice were subjected to renal ischemia/reperfusion (I/R) and treated daily with lasmiditan (0.3 mg/kg) or vehicle beginning 24 h after injury for 3 or 6d. Serum creatinine was measured to estimate glomerular filtration. Electron microscopy was used to assess mitochondrial morphology and mitophagy. Mitochondrial-related protein were confirmed with immunoblotting. Mitochondrial function was assessed with ATP measurements.

RESULTS

Lasmiditan treatment improved mitochondrial and kidney recovery as early as 3d post-AKI, as evidenced by increased ATP, and decreased serum creatinine, respectively. Electron micrographs of renal cortices revealed that lasmiditan also decreased mitochondrial damage and increased mitochondrial area and size by 6d after I/R injury. Additionally, lasmiditan treatment increased mitolysosomes by 3d, indicating induction of mitophagy. Phosphorylation of mitophagy-related proteins were also increased in the renal cortices of lasmiditan-treated AKI mice 3d after I/R injury, whereas fusion-related proteins were increased at 6d after I/R injury.

CONCLUSION

These data reveal that lasmiditan accelerates renal recovery, restores normal mitochondrial membrane and cristae morphology, decreases excessive mitochondrial fission, and accelerates mitophagy post-AKI in a time-dependent manner, establishing mitochondrial function and recovery from AKI.

Association of early postoperative serum magnesium with acute kidney injury after cardiac surgery

INTRODUCTION

Dysmagnesemia has been demonstrated to be involved in the pathophysiology of kidney diseases and is common in cardiac surgical patients. It remains unknown whether changes of serum magnesium after cardiac surgery affect AKI. We aimed to investigate the association of early postoperative magnesium with cardiac surgery-associated AKI in adults.

METHODS

We conducted a multicenter retrospective cohort study involving patients who underwent cardiac surgery in the eICU Collaborative Research Database between 2014 and 2015. AKI within 7 days after surgery was defined using both serum creatinine and urine output criteria of Kidney Disease Improving Global Outcomes definition. Postoperative AKI was analyzed using multivariable logistic regression with early postoperative serum magnesium measured within the first 24 h after surgery as a continuous variable and categorically by quartiles.

RESULTS

Postoperative AKI was identified in 3498 of 6124 (57.1%) patients receiving cardiac surgery. The median (25th-75th percentiles) early postoperative serum magnesium level of the study population was 2.3 (2.0-2.7) mg/dL. Higher serum magnesium level was associated with a higher risk of developing postoperative AKI (adjusted odds ratio (OR), 1.46 per 1 mg/dL increase; 95% confidence interval (CI), 1.31-1.62; p<.001). The multivariable-adjusted ORs (95% CIs) of postoperative AKI across increasing quartiles of serum magnesium were 1.00 (referent), 1.11 (0.95-1.29), 1.30 (1.12-1.52), and 1.72 (1.47-2.02) (p for trend <.001).

CONCLUSIONS

These data demonstrate a significantly higher incidence of AKI in patients with higher early postoperative serum magnesium who underwent cardiac surgery.

Incidence and prognosis of acute kidney injury versus acute kidney disease among 71 041 inpatients

Background

Acute kidney disease (AKD) defines patients with acute kidney injury (AKI) or subacute loss of kidney function lasting for >7 days. Little is known about the prognosis of AKD in hospitalized patients. The aim of this study was to investigate the risk factors and prognosis of AKD and to compare different types of acute/subacute renal impairment among Chinese inpatients.

Methods

Complete data were available for 71 041 patients for a range of 5-63 months. AKI and AKD were diagnosed based on the Acute Disease Quality Initiative criteria of 2017.

Results

Of 71 041 inpatients, 16 098 (22.7%) patients developed AKI or AKD; 5895 (8.3%) AKI patients recovered within 7 days, 5623 (7.9%) AKI patients developed AKD and 4580 (6.4%) patients developed AKD without AKI. Mortality was proportional to stages of AKI and AKD (P < .05), while AKI followed by AKD was associated with a higher risk of long-term mortality [hazard ratio (HR) 4.51] as compared with AKD without AKI (HR 2.25) and recovery from AKI (HR 1.18). The AKD criteria were robustly associated with overall survival [area under the receiver operating characteristic curve (AUROC) 0.71] and de novo CKD (AUROC 0.71), while the AKI criteria showed a relatively lower ability to fit the risk of overall survival (AUROC 0.65) and CKD (AUROC 0.63).

Conclusions

AKD and AKD stages are useful clinical definitions for clinical practice, as they predict unfortunate clinical outcomes such as overall long-term mortality and CKD. Research activities should focus on AKD.

Typhaneoside-Tetrahedral Framework Nucleic Acids System: Mitochondrial Recovery and Antioxidation for Acute Kidney Injury treatment

Acute kidney injury (AKI) is not only a worldwide problem with a cruel hospital mortality rate but also an independent risk factor for chronic kidney disease and a promoting factor for its progression. Despite supportive therapeutic measures, there is no effective treatment for AKI. This study employs tetrahedral framework nucleic acid (tFNA) as a vehicle and combines typhaneoside (Typ) to develop the tFNA-Typ complex (TTC) for treating AKI. With the precise targeting ability on mitochondria and renal tubule, increased antiapoptotic and antioxidative effect, and promoted mitochondria and kidney function restoration, the TTC represents a promising nanomedicine for AKI treatment. Overall, this study has developed a dual-targeted nanoparticle with enhanced therapeutic effects on AKI and could have critical clinical applications in the future.

Clinical decision limits as criteria for setting analytical performance specifications for laboratory tests

BACKGROUND

The biological (CV_I), preanalytical (CV_PRE), and analytical variation (CV_A) are inherent to clinical laboratory testing and consequently, interpretation of clinical test results.

METHODS

The sum of the CV_I, CV_PRE, and CV_A, called diagnostic variation (CV_D), was used to derive clinically acceptable analytical performance specifications (CAAPS) for clinical chemistry measurands. The reference change concept was applied to clinically significant differences (CD) between two measurements, with the formula CD = z*√2* CV_D. CD for six measurands were sought from international guidelines. The CAAPS were calculated by subtracting variances of CV_I and CV_PRE from CV_D. Modified formulae were applied to consider statistical power (1-β) and repeated measurements.

RESULTS

The obtained CAAPS were 44.9% for urine albumin, 0.6% for plasma sodium, 22.9% for plasma pancreatic amylase, and 8.0% for plasma creatinine (z = 3, α = 2.5%, 1-β = 85%). For blood HbA_1c and plasma low-density lipoprotein cholesterol, replicate measurements were necessary to reach CAAPS for patient monitoring. The derived CAAPS were compared with analytical performance specifications, APS, based on biological variation.

CONCLUSIONS

The CAAPS models pose a new tool for assessing APS in a clinical laboratory. Their usability depends on the relevance of CD limits, required statistical power and the feasibility of repeated measurements.

Role of necroptosis in kidney health and disease

Cell death, particularly that of tubule epithelial cells, contributes critically to the pathophysiology of kidney disease. A body of evidence accumulated over the past 15 years has ascribed a central pathophysiological role to a particular form of regulated necrosis, termed necroptosis, to acute tubular necrosis, nephron loss and maladaptive renal fibrogenesis. Unlike apoptosis, which is a non-immunogenic process, necroptosis results in the release of cellular contents and cytokines, which triggers an inflammatory response in neighbouring tissue. This necroinflammatory environment can lead to severe organ dysfunction and cause lasting tissue injury in the kidney. Despite evidence of a link between necroptosis and various kidney diseases, there are no available therapeutic options to target this process. Greater understanding of the molecular mechanisms, triggers and regulators of necroptosis in acute and chronic kidney diseases may identify shortcomings in current approaches to therapeutically target necroptosis regulators and lead to the development of innovative therapeutic approaches.

Clinical Profile of Patients with Hypertensive Emergency Referred to a Tertiary Hospital in the Western Cape Province of South Africa

BACKGROUND

Despite advances in managing hypertension, hypertensive emergencies remain a common indication for emergency room visits. Our study aimed to determine the clinical profile of patients referred with hypertensive emergencies.

METHODS

We conducted an observational study involving patients aged ≥18 years referred with hypertensive crisis. A diagnosis of hypertensive emergencies was based on a systolic blood pressure (BP) ≥180 mmHg and/or a diastolic BP ≥110 mmHg, with acute hypertension-mediated organ damage (aHMOD). Patients without evidence of aHMOD were considered hypertensive urgencies. Hypertensive disorders of pregnancy and unconscious patients were excluded from the study.

RESULTS

Eighty-two patients were included, comprising 66 (80.5%) with hypertensive emergencies and 16 (19.5%) with hypertensive urgencies. The mean age of patients with hypertensive emergencies was 47.9 (13.2) years, and 66.7% were males. Age, systolic BP, and duration of hypertension were similar in the hypertensive crisis cohort. Most patients with hypertensive emergencies reported nonadherence to medication (78%) or presented de novo without a prior diagnosis of hypertension (36%). Cardiac aHMOD (acute pulmonary edema and myocardial infarction) occurred in 66%, while neurological emergencies (intracranial hemorrhage, ischemic stroke, and hypertensive encephalopathy) occurred in 33.3%. Lactate dehydrogenase (LDH) (P < 0.001), NT-proBNP (P=0.024), and cardiac troponin (P<0.001) were higher in hypertensive emergencies compared to urgencies. LDH did not differ in the subtypes of hypertensive emergencies.

CONCLUSION

Cardiovascular and neurological emergencies are the most common hypertensive emergencies. Most patients reported nonadherence to medication or presented de novo without a prior diagnosis of hypertension.

Early Postoperative Acetaminophen Administration and Severe Acute Kidney Injury After Cardiac Surgery

RATIONALE & OBJECTIVE

Oxidative stress may contribute to the development of acute kidney injury (AKI) after cardiac surgery. Acetaminophen can be considered an antioxidant because it inhibits hemoprotein-catalyzed lipid peroxidation. We hypothesized that perioperative acetaminophen administration is associated with reduced AKI after cardiac surgery.

STUDY DESIGN

Retrospective observational cohort study.

SETTING & PARTICIPANTS

Patients aged≥18 years who had cardiac surgery were identified from 2 publicly available clinical registries: the Medical Information Mart for Intensive Care III (MIMIC-III) and the eICU Collaborative Research Database (eICU).

EXPOSURE

Administration of acetaminophen in the first 48 hours after surgery.

OUTCOME

Severe AKI in the first 7 days after surgery, defined as stage 2 or stage 3 AKI according to KDIGO criteria.

ANALYTICAL APPROACH

Multivariable cause-specific hazards regression analysis.

RESULTS

We identified 5,791 patients from the MIMIC-III and 3,840 patients from the eICU registries. The overall incidence of severe AKI was 58% (3,390 patients) in the MIMIC-III cohort and 37% (1,431 patients) in the eICU cohort. Acetaminophen was administered in the early postoperative period to 4,185 patients (72%) and 2,737 patients (71%) in these 2 cohorts, respectively. In multivariable regression models, early postoperative use of acetaminophen was associated with a lower risk of severe AKI in both the MIMIC-III (adjusted hazard ratio [AHR], 0.86 [95% CI, 0.79-0.94]) and eICU (AHR, 0.84 [95% CI, 0.72-0.97]) cohorts. The benefit was consistent across sensitivity and subgroup analyses.

LIMITATIONS

No data on acetaminophen dose.

CONCLUSIONS

Early postoperative acetaminophen administration was independently associated with a lower risk of severe AKI in adults recovering from cardiac surgery. Prospective trials are warranted to assess the extent to which the observed association is causal and estimate the extent to which acetaminophen administration might prevent or reduce the severity of AKI.

Multistate Modeling of Clinical Trajectories and Outcomes in the ICU: A Proof-of-Concept Evaluation of Acute Kidney Injury Among Critically Ill Patients With COVID-19

Multistate models yield high-fidelity analyses of the dynamic state transition and temporal dimensions of a clinical condition's natural history, offering superiority over aggregate modeling techniques for addressing these types of problems.

OBJECTIVES

To demonstrate the utility of these models in critical care, we examined acute kidney injury (AKI) development, progression, and outcomes in COVID-19 critical illness through multistate analyses.

DESIGN SETTING AND PARTICIPANTS

Retrospective cohort study at an urban tertiary-care academic hospital in the United States. All patients greater than or equal to 18 years in an ICU with COVID-19 in 2020, excluding patients with preexisting end-stage renal disease.

MAIN OUTCOMES AND MEASURES

Using electronic health record data, we determined AKI presence/stage in discrete 12-hour time windows and fit multistate models to determine longitudinal transitions and outcomes.

RESULTS

Of 367 encounters, 241 (66%) experienced AKI (maximal stages: 88 stage-1, 49 stage-2, 104 stage-3 AKI [51 received renal replacement therapy (RRT), 53 did not]). Patients receiving RRT overwhelmingly received invasive mechanical ventilation (IMV) (n = 60, 95%) compared with the AKI-without-RRT (n = 98, 53%) and no-AKI groups (n = 39, 32%; p < 0.001), with similar mortality patterns (RRT: n = 36, 57%; AKI: n = 74, 40%; non-AKI: n = 23, 19%; p < 0.001). After 24 hours in the ICU, almost half the cohort had AKI (44.9%; 95% CI, 41.6-48.2%). At 7 days after stage-1 AKI, 74.0% (63.6-84.4) were AKI-free or discharged. By contrast, fewer patients experiencing stage-3 AKI were recovered (30.0% [24.1-35.8%]) or discharged (7.9% [5.2-10.7%]) after 7 days. Early AKI occurred with similar frequency in patients receiving and not receiving IMV: after 24 hours in the ICU, 20.9% of patients (18.3-23.6%) had AKI and IMV, while 23.4% (20.6-26.2%) had AKI without IMV.

CONCLUSIONS AND RELEVANCE

In a multistate analysis of critically ill patients with COVID-19, AKI occurred early and heterogeneously in the course of critical illness. Multistate methods are useful and underused in ICU care delivery science as tools for understanding trajectories, prognoses, and resource needs.