Oliguria as predictive biomarker of acute kidney injury in critically ill patients

Clinical Assessment of Fluid Status in Adults With Acute Kidney Injury: A Scoping Review

BACKGROUND

Acute kidney injury refers to sudden, potentially reversible, reduction in kidney function. Hypovolaemia is commonly the major risk factor. When acute kidney injury is established, fluid can accumulate leading to fluid overload. Undertaking a rigorous fluid assessment is vital in the management of a patient in hospital with acute kidney injury, as insufficient or excessive fluid can lead to increased morbidity and mortality.

OBJECTIVES

The aim of this scoping review is to identify which clinical assessments are useful when undertaking fluid assessment in a patient with acute kidney injury, and to identify signs and symptoms of fluid overload or dehydration in patients in hospital with acute kidney injury.

DESIGN

The JBI methodology for scoping reviews was followed and reported using the PRISMA-ScR checklist. PubMed, CINAHL Plus and SCOPUS were searched for research papers relating to the signs and symptoms or fluid assessments in patients with acute kidney injury.

RESULTS

Fifteen research papers were identified with four key areas being: Fluid balance/urine output and weight; early warning scores; clinical signs and symptoms; holistic assessment. The primary studies included in this scoping review have shown that hypovolaemia may be indicated by low blood pressure, orthostatic hypotension, low Mean Arterial Pressure, elevated heart rate, prolonged capillary refill time on the sternum (> 4.5 s) and subjectively reported cold peripheries. With clinical symptoms including dry mouth, increased thirst and dry skin. Accurate documentation of urine output and fluid balance is crucial in determining fluid status.

CONCLUSION

The assessment of fluid should be holistic and include history taking, diagnosis, blood tests and associated clinical signs and symptoms.

The combination of kidney function variables with cell cycle arrest biomarkers identifies distinct subphenotypes of sepsis-associated acute kidney injury: a post-hoc analysis (the PHENAKI study)

BACKGROUND

The severity and course of sepsis-associated acute kidney injury (SA-AKI) are correlated with the mortality rate. Early detection of SA-AKI subphenotypes might facilitate the rapid provision of individualized care.

PATIENTS AND METHODS

In this post-hoc analysis of a multicenter prospective study, we combined conventional kidney function variables with serial measurements of urine (tissue inhibitor of metalloproteinase-2 [TIMP-2])* (insulin-like growth factor-binding protein [IGFBP7]) at 0, 6, 12, and 24 h) and then using an unsupervised hierarchical clustering of principal components (HCPC) approach to identify different phenotypes of SA-AKI. We then compared the subphenotypes with regard to a composite outcome of in-hospital death or the initiation of renal replacement therapy (RRT).

RESULTS

We included 184 patients presenting SA-AKI within 6 h of the initiation of catecholamines. Three distinct subphenotypes were identified: subphenotype A (99 patients) was characterized by a normal urine output (UO), a low SCr and a low [TIMP-2]*[IGFBP7] level; subphenotype B (74 patients) was characterized by existing chronic kidney disease (CKD), a higher SCr, a low UO, and an intermediate [TIMP-2]*[IGFBP7] level; and subphenotype C was characterized by very low UO, a very high [TIMP-2]*[IGFBP7] level, and an intermediate SCr level. With subphenotype A as the reference, the adjusted hazard ratio (aHR) [95%CI] for the composite outcome was 3.77 [1.92-7.42] (p < 0.001) for subphenotype B and 4.80 [1.67-13.82] (p = 0.004) for subphenotype C.

CONCLUSIONS

Combining conventional kidney function variables with urine measurements of [TIMP-2]*[IGFBP7] might help to identify distinct SA-AKI subphenotypes with different short-term courses and survival rates.

Clinical characteristics and outcomes of patients on haemodialysis at Jimma medical center, Ethiopia: a 7-Year review

BACKGROUND

Haemodialysis is the primary kidney replacement therapy modality in Africa. In Ethiopia, the number of patients undergoing Haemodialysis is increasing, yet data on their outcomes is scarce. This study assesses the clinical characteristics and outcomes of Haemodialysis patients at Jimma Medical Center.

METHODS

A retrospective cross-sectional study was conducted from April 08 to 12, 2024, involving patients who underwent Haemodialysis at Jimma Medical Center from June 2017 to March 2024. The data were coded and entered into EpiData version 3.1, then exported to the Statistical Package for Social Sciences version 26.0 for analysis. Descriptive statistics summarized the patients' clinical characteristics and outcomes, and Kaplan-Meier curves were used to assess survival status.

RESULTS

During the seven-year study period, 68 patients underwent Haemodialysis at Jimma Medical Center, with a predominance of males (69.1%). The average age of patients was 42.7 (± 12.8) years with 69.1% (95% CI: 57.5-79.1%) diagnosed with chronic kidney disease, while 30.9% (95% CI: 20.9-42.5%) had acute kidney injury. Among chronic kidney disease patients, common clinical features included nausea and vomiting (100%), proteinuria (95.7%), and body swelling (82.9%), while acute kidney injury patients frequently presented with oliguria (100%), nausea and vomiting (90.5%), and hematuria (52.4%). Hypertensive nephropathy was the leading cause of chronic kidney disease (40.4%), and acute glomerulonephritis (38.1%) and severe malaria (33.3%) were the predominant causes of acute kidney injury. Mortality was observed at 47.6% (95% CI: 27.7-68.6%) in acute kidney injury patients and 40.4% (95% CI: 27.3-54.7%) in chronic kidney disease patients. Emergency vascular access was required in 95.7% of chronic kidney disease and 100% of acute kidney injury patients.

CONCLUSION

This study highlights the substantial burden of chronic kidney disease and acute kidney injury among hemodialysis patients at Jimma Medical Center, revealing distinct clinical profiles and outcomes. Although acute kidney injury patients exhibited a longer median survival time, the significant mortality risk within the first year underscores the urgent need for improved treatment access and resource allocation. Enhancing early intervention and ensuring the availability of critical medications, such as erythropoietin, are essential for optimizing patient outcomes for both chronic kidney disease and acute kidney injury groups.

CLINICAL TRIAL NUMBER

Not applicable.

Association between lactate dehydrogenase to albumin ratio and acute kidney injury in patients with sepsis: a retrospective cohort study

BACKGROUND

Serum lactate dehydrogenase to albumin ratio (LAR) is associated with poor outcomes in malignancy and pneumonia. However, there are few studies suggesting that LAR is associated with the occurrence of acute kidney injury (AKI) in patients with sepsis, which was investigated in this study.

METHODS

We conducted a retrospective cohort study based on the Medical Information Mart for Intensive Care (MIMIC)-IV database. The primary outcome was the occurrence of AKI within 2 days and 7 days. Multivariable logistic regression models were used to calculate odds ratios to validate the association between LAR and AKI, in-hospital mortality, RRT use, and recovery of renal function, respectively.

RESULTS

A total of 4010 participants were included in this study. The median age of the participants was 63.5 years and the median LAR was 10.5. After adjusting for confounding variables, patients in the highest LAR quartile had a higher risk of AKI than those in the lowest LAR quartile within 2 days and 7 days, with odds ratios of 1.37 (95% confidence interval [CI]: 1.23-1.52) and 1.95 (95% CI: 1.72-2.22), respectively. The adjusted odds of AKI within 2 and 7 days were 1.16 (95% CI: 1.12-1.20) and 1.29 (95% CI: 1.24-1.35) for each 1 unit increase in LAR(log2), respectively.

CONCLUSION

This study demonstrated that elevated LAR was associated with poor prognosis in patients with sepsis. The risk of AKI and in-hospital mortality increased, the need for RRT increased, and the chance of recovery of renal function decreased with the increase of LAR.

Redefining urine output thresholds for acute kidney injury criteria in critically Ill patients: a derivation and validation study

INTRODUCTION

The current definition of acute kidney injury (AKI) includes increased serum creatinine (sCr) concentration and decreased urinary output (UO). Recent studies suggest that the standard UO threshold of 0.5 ml/kg/h may be suboptimal. This study aimed to develop and validate a novel UO-based AKI classification system that improves mortality prediction and patient stratification.

METHODS

Data were obtained from the MIMIC-IV and eICU databases. The development process included (1) evaluating UO as a continuous variable over 3-, 6-, 12-, and 24-h periods; (2) identifying 3 optimal UO cutoff points for each time window (stages 1, 2, and 3); (3) comparing sensitivity and specificity to develop a unified staging system; (4) assessing average versus persistent reduced UO hourly; (5) comparing the new UO-AKI system to the KDIGO UO-AKI system; (6) integrating sCr criteria with both systems and comparing them; and (7) validating the new classification with an independent cohort. In all these steps, the outcome was hospital mortality. Another analyzed outcome was 90-day mortality. The analyses included ROC curve analysis, net reclassification improvement (NRI), integrated discrimination improvement (IDI), and logistic and Cox regression analyses.

RESULTS

From the MIMIC-IV database, 35,845 patients were included in the development cohort. After comparing the sensitivity and specificity of 12 different lowest UO thresholds across four time frames, 3 cutoff points were selected to compose the proposed UO-AKI classification: stage 1 (0.2-0.3 mL/kg/h), stage 2 (0.1-0.2 mL/kg/h), and stage 3 (< 0.1 mL/kg/h) over 6 h. The proposed classification had better discrimination when the average was used than when the persistent method was used. The adjusted odds ratio demonstrated a significant stepwise increase in hospital mortality with advancing UO-AKI stage. The proposed classification combined or not with the sCr criterion outperformed the KDIGO criteria in terms of predictive accuracy-AUC-ROC 0.75 (0.74-0.76) vs. 0.69 (0.68-0.70); NRI: 25.4% (95% CI: 23.3-27.6); and IDI: 4.0% (95% CI: 3.6-4.5). External validation with the eICU database confirmed the superior performance of the new classification system.

CONCLUSION

The proposed UO-AKI classification enhances mortality prediction and patient stratification in critically ill patients, offering a more accurate and practical approach than the current KDIGO criteria.

CCL14 Predicts Oliguria and Dialysis Requirement in Patients with Moderate to Severe Acute Kidney Injury

INTRODUCTION

AKI is a frequent complication of critical illness and portends poor outcome. CCL14 is a validated predictor of persistent severe AKI in critically ill patients. We examined the association of CCL14 with urine output within 48 h.

METHODS

In pooled data from 2 studies of critically ill patients with KDIGO stage 2-3 AKI, CCL14 was measured by NEPHROCLEAR™ CCL14 Test on the Astute 140® Meter (low, intermediate, and high categories [1.3 and 13 ng/mL]). Average hourly urine output over 48 h, stage 3 AKI per urine output criterion on day 2, and composite of dialysis or death within 7 days were examined using multivariable mixed and logistic regression models.

RESULTS

Of the 497 subjects with median age of 65 (56-74) years, 49% (242/497) were on diuretics. CCL14 concentration was low in 219 (44%), intermediate in 217 (44%), and high in 61 (12%) patients. In mixed regression analysis, hourly urine output over time was different within each CCL14 risk category based on diuretic use due to significant three-way interaction (p < 0.001). In logistic regression analysis, CCL14 risk category was independently associated with low urine output on day 2 per KDIGO stage 3 (adjusted for diuretic use and baseline clinical variables), and composite of dialysis or death within 7 days (adjusted for urine output within 48 h of CCL14 measurement).

CONCLUSIONS

CCL14 measured in patients with moderate to severe AKI is associated with urine output trajectory within 48 h, oliguria on day 2, and dialysis within 7 days.

Digitizing fluid balance monitoring may offer a solution for optimizing patient care

BACKGROUND

Precise fluid balance monitoring is essential for patient treatment, as incorrect fluid balance can lead to disorders.

OBJECTIVE

This study aimed to assess the accuracy of the digital technology LICENSE (LIquid balanCE moNitoring SystEm) for fluid balance charting and compare it to the standard method (SM) to determine its usability in clinical practice.

METHODS

This prospective study included 20 patients. The results from LICENSE were compared to those from SM and a reference measurement (manual weight of fluids, RM). Three LICENSE devices were used for urine output, intravenous fluids, and oral fluid intake. The accuracy of methods was evaluated using Bland Altman plots.

RESULTS

The mean difference between LICENSE and RM was less than 2 millilitres (p= 0.031 and p= 0.047), whereas the mean difference between SM and RM was 6.6 ml and 10.8 ml (p< 0.0001). The range between the upper and lower limits of agreement was between 16.4 and 27.8 ml for LICENSE measurements and 25.2 and 52 ml for SM.

CONCLUSION

LICENSE is comparable to or more accurate than the standard method for fluid balance monitoring. The use of LICENSE may improve the accuracy of fluid balance measurements. Further research is needed to evaluate its feasibility in daily clinical practice.

A new criteria for acute on preexisting kidney dysfunction in critically ill patients

Critically ill patients with preexisting kidney dysfunction (PKD) are at high risk for acute kidney injury (AKI). Nevertheless, there is no criteria for screening and classifying AKI in patients with PKD. In this study, after assessing relationship between the change in SCr from baseline and in-hospital mortality, a new criteria, named APKD, for identifying AKI in PKD was proposed. APKD defined AKI in critically ill patients with PKD as an absolute increase of ≥ 0.2 mg/dL in SCr within 48 h or an increase in SCr ≥ 1.1 times over baseline within 7 d. APKD detected more AKI among PKD patients compared with the other criteria. Additionally, the AKI patients identified by APKD but missed by the other criteria had higher mortality than those without AKI. APKD shows higher sensitivities than KDIGO criteria in predicating in-hospital mortality. APKD, but not the KDIGO, is effective for staging the severity of AKI in patients with PKD. In conclusion, APKD is more effective in screening and classifying AKI in critically ill patients with PKD compared with the earlier criteria, and it may helpful in guiding clinical treatment and predicting prognosis.

Definition, Staging, and Role of Biomarkers in Acute Kidney Injury in the Context of Cardiovascular Interventions

Acute kidney injury (AKI) is a frequently occurring complication of cardiovascular interventions, and associated with adverse outcomes. Therefore, a clear definition of AKI is of paramount importance to enable timely recognition and treatment. Historically, changes in the serum creatinine and urine output have been used to define AKI, and the criteria have evolved over time with better understanding of the impact of AKI on the outcomes. However, the reliance on serum creatinine for these AKI definitions carries numerous limitations including delayed rise, inability to differentiate between hemodynamics versus structural injury and assay variability to name a few.

Urine output as one of the most important features in differentiating in-hospital death among patients receiving extracorporeal membrane oxygenation: a random forest approach

BACKGROUND

It is common to support cardiovascular function in critically ill patients with extracorporeal membrane oxygenation (ECMO). The purpose of this study was to identify patients receiving ECMO with a considerable risk of dying in hospital using machine learning algorithms.

METHODS

A total of 1342 adult patients on ECMO support were randomly assigned to the training and test groups. The discriminatory power (DP) for predicting in-hospital mortality was tested using both random forest (RF) and logistic regression (LR) algorithms.

RESULTS

Urine output on the first day of ECMO implantation was found to be one of the most predictive features that were related to in-hospital death in both RF and LR models. For those with oliguria, the hazard ratio for 1 year mortality was 1.445 (p < 0.001, 95% CI 1.265-1.650).

CONCLUSIONS

Oliguria within the first 24 h was deemed especially significant in differentiating in-hospital death and 1 year mortality.

Identification of an optimal threshold to define oliguria in critically ill patients: an observational study

BACKGROUND

The relevance of current consensus threshold to define oliguria has been challenged by small observational studies. We aimed to determine the optimal threshold to define oliguria in critically-ill patients.

METHODS

Cohort study including adult patients admitted within a multi-disciplinary intensive care unit between January 1st 2010 and June 15th 2020. Patients on chronic dialysis or who declined consent were excluded. We extracted hourly urinary output (UO) measurements along with patient's characteristics from electronic medical records and 90-day mortality from the Swiss national death registry. We randomly split our data into a training (80%) and a validation (20%) set. In the training set, we developed multivariable models to assess the relationship between 90-day mortality and the minimum average UO calculated over time windows of 3, 6, 12 and 24 h. Optimal thresholds were determined by visually identifying cut-off values for the minimum average UO below which predicted mortality increased substantially. We tested models' discrimination and calibration on the entire validation set as well as on a subset of patients with oliguria according to proposed thresholds.

RESULTS

Among the 15,500 patients included in this analysis (training set: 12,440, validation set: 3110), 73.0% (95% CI [72.3-73.8]) presented an episode of oliguria as defined by consensus criteria (UO < 0.5 ml/kg/h for 6 h). Our models had excellent (AUC > 85% for all time windows) discrimination and calibration. The relationship between minimum average UO and predicted 90-day mortality was nonlinear with an inflexion point at 0.2 ml/kg/h for 3 and 6 h windows and 0.3 ml/kg/h for 12 and 24 h windows. Considering a threshold of < 0.2 ml/kg/h over 6 h, the proportion of patients with an episode of oliguria decreased substantially to 24.7% (95% CI [24.0-25.4]). Contrary to consensus definition, this threshold identified a population with a higher predicted 90-day mortality.

CONCLUSIONS

The widely used cut-off for oliguria of 0.5 ml/kg/h over 6 h may be too conservative. A cut-off of 0.2 ml/kg/h over 3 or 6 h is supported by the data and should be considered in further definitions of oliguria.

Feasibility of an electronic fluid balance chart to detect and understand the significance of oliguric acute kidney injury in a general ward setting: a prospective observational cohort study

Background

Outside critical care environments, few studies have assessed the significance of oliguric acute kidney injury (AKI). This study investigated the feasibility of an electronic fluid balance chart to diagnose oliguric AKI. Data were used to determine if oliguric AKI was met earlier than creatinine AKI and to establish outcomes of those who developed AKI.

Methods

A single-centre prospective cohort study investigated Kidney Disease Improving Global Outcomes oliguric and creatinine AKI criteria on general surgical wards.

Results

2,149 cases were included in the analysis. Incidence of oliguric AKI was significantly higher than creatinine criteria (73 versus 10.1%) and detection occurred earlier (2.1 versus 6.1 days, p<0.05). In cases with oliguric AKI, 8.1% also developed AKI by creatinine criteria. In cases not meeting oliguric AKI criteria, fewer cases developed creatinine AKI, as compared to those meeting oliguric AKI criteria (7.9% versus 11%, p=0.043). There was a high incidence of missing data.

Conclusions

Oliguric AKI was met in a high proportion of cases and occurred earlier than by changes in creatinine. Barriers to consistency of recording must be addressed before oliguric criteria could be implemented in clinical practice.

Improving awareness of kidney function through electronic urine output monitoring: a comparative study

BACKGROUND

The current classification for acute kidney injury (AKI) according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria integrates both serum creatinine (SCr) and urine output (UO). Most reports on AKI claim to use KDIGO guidelines but fail to include the UO criterion. It has been shown that patients who had intensive UO monitoring, with or without AKI, had significantly less cumulative fluid volume and fluid overload, reduced vasopressor use, and improved 30-day mortality. We examined whether real-time monitoring of this simple, sensitive, and easy-to-use biomarker in the ICU led to more appropriate intervention by healthcare providers and better outcomes.  METHODS: RenalSense Clarity RMS Consoles were installed in the General ICU at the Hadassah Medical Center, Israel, from December 2019 to November 2020. The Clarity RMS system continuously and electronically monitors UO in real-time. 100 patients were randomly selected from this period as the study group (UO_elec) and compared to a matched control group (UO_manual) from the same period two years earlier. To test whether there was an association between oliguric hours and fluid treatment in each group, the correlation was calculated and analyzed for each of the different UO monitoring methods.

RESULTS

Therapeutic intervention: The correlation of the sum of all oliguric hours on Day 1 and 2 with the sum of any therapeutic intervention (fluid bolus or furosemide) showed a significant correlation for the study group UO_elec (P = 0.017). The matched control group UO_manual showed no such correlation (P = 0.932). Length of Stay (LOS): Median LOS [IQR] in the ICU of UO_elec versus UO_manual was 69.46 [44.7, 125.9] hours and 116.5 [62.46, 281.3] hours, respectively (P = 0.0002).

CONCLUSIONS

The results of our study strongly suggest that ICU patients had more meaningful and better medical intervention, and improved outcomes, with electronic UO monitoring than with manual monitoring.

Association between intraoperative oliguria and postoperative acute kidney injury in non-cardiac surgical patients: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to evaluate the association between intraoperative oliguria and the risk of postoperative acute kidney injury (AKI) in patients undergoing non-cardiac surgery.

METHODS

The MEDLINE and EMBASE databases were searched up to August 2022 for studies in adult patients undergoing non-cardiac surgery, where the association between intraoperative urine output and the risk of postoperative AKI was assessed. Both randomised and non-randomised studies were eligible for inclusion. Study selection and risk of bias assessment were independently performed by two investigators. The risk of bias was evaluated using the Newcastle-Ottawa scale. We performed meta-analysis of the reported multivariate adjusted odds ratios for the association between intraoperative oliguria (defined as urine output < 0.5 mL/kg/hr) and the risk of postoperative AKI using the inverse-variance method with random effects models. We conducted sensitivity analyses using varying definitions of oliguria as well as by pooling unadjusted odds ratios to establish the robustness of the primary meta-analysis. We also conducted subgroup analyses according to surgery type and definition of AKI to explore potential sources of clinical or methodological heterogeneity.

RESULTS

Eleven studies (total 49,252 patients from 11 observational studies including a post hoc analysis of a randomised controlled trial) met the selection criteria. Seven of these studies contributed data from a total 17,148 patients to the primary meta-analysis. Intraoperative oliguria was associated with a significantly elevated risk of postoperative AKI (pooled adjusted odds ratio [OR] 1.74; 95% confidence interval [CI] 1.36-2.23, p < 0.0001, 8 studies). Sensitivity analyses supported the robustness of the primary meta-analysis. There was no evidence of any significant subgroup differences according to surgery type or definition of AKI.

CONCLUSIONS

This study demonstrated a significant association between intraoperative oliguria and the risk of postoperative AKI, regardless of the definitions of oliguria or AKI used. Further prospective and multi-centre studies using standardised definitions of intraoperative oliguria are required to define the thresholds of oliguria and establish strategies to minimise the risk of AKI.

Clinical profile and predictors of renal failure in emergency department patients at a tertiary level hospital, a cross sectional study

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Our study was able to highlight the profile of patients at risk of renal failure who were likely older, hypertensive, oliguric and with low hemoglobin compared to those without.

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This Knowledge can help care givers and policy makers to pay particular attention and institute interventions targeted at treating non communicable diseases (that lead to renal failure) and infections there by reducing progressing to renal failure and end stage renal disease with need for renal replacement therapy.

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In addition, it also showed that simple bedside tests like dip stick urinalysis and urine output monitoring are key in surveillance of renal failure.

Background

Since establishment of the emergency departments (ED) in the country, there is lack of information on clinical profile of patients admitted to the ED and predictors of renal failure in these patients. Renal failure is prevalent in critical patients and a cause of significant mortality and morbidity. The aim of this study was to assess the clinical profile and predictors of renal failure in admissions to the ED.

Methods

This was a cross-sectional study that was conducted at a tertiary level hospital in Zambia from January to December, 2019 among admissions to the ED after ethical approval. The primary outcome of the study was to describe the clinical profile of admissions to the ED and proportion of renal failure defined as estimated glomerular filtration rate (eGFR) < 60 mls/1.72 m²

Results

The final analysis includes 152 patients, 7 excluded for missing key data. The median age was 43.5 years (IQR 32.5-59.5) and 94.7% of patients were medical. Nearly 70.0% of the patients were triaged as emergency (red) or very urgent (orange). The reason for admission to the ED were sepsis and/or sepsis shock in 25.0%, diabetic hyperglycaemia emergencies in 20.0%, hypertensive crisis in 10.5%, respiratory failure (9.9%), severe malaria (7.9%) and poisoning (5.0%). The prevalence of renal failure was 36.1% and proteinuria was observed in 23.0%. Oliguria and hypertension were 5.9-fold and 1.7-fold independent predictors of renal failure in the ED. Patients with renal failure were likely older, hypertensive, oliguric and anaemic compared to those without. During admission to the ED, 19.1% died.

Conclusion

Sepsis and diabetic and hypertensive emergencies accounted for nearly half of ED admissions. Hypertension and oliguria were key predictors of renal failure. Early diagnosis, management and follow-up of hypertension including urine output monitoring for high-risk patients is key in surveillance and prevention of renal failure.

Accuracy of clinicians' ability to predict the need for renal replacement therapy: a prospective multicenter study

PURPOSE

Identifying patients who will receive renal replacement therapy (RRT) during intensive care unit (ICU) stay is a major challenge for intensivists. The objective of this study was to evaluate the performance of physicians in predicting the need for RRT at ICU admission and at acute kidney injury (AKI) diagnosis.

METHODS

Prospective, multicenter study including all adult patients hospitalized in 16 ICUs in October 2020. Physician prediction was estimated at ICU admission and at AKI diagnosis, according to a visual Likert scale. Discrimination, risk stratification and benefit of physician estimation were assessed. Mixed logistic regression models of variables associated with risk of receiving RRT, with and without physician estimation, were compared.

RESULTS

Six hundred and forty-nine patients were included, 270 (41.6%) developed AKI and 77 (11.8%) received RRT. At ICU admission and at AKI diagnosis, a model including physician prediction, the experience of the physician, SOFA score, serum creatinine and diuresis to determine need for RRT performed better than a model without physician estimation with an area under the ROC curve of 0.90 [95% CI 0.86-0.94, p < 0.008 (at ICU admission)] and 0.89 [95% CI 0.83-0.93, p = 0.0014 (at AKI diagnosis)]. In multivariate analysis, physician prediction was strongly associated with the need for RRT, independently of creatinine levels, diuresis, SOFA score and the experience of the doctor who made the prediction.

CONCLUSION

As physicians are able to stratify patients at high risk of RRT, physician judgement should be taken into account when designing new randomized studies focusing on RRT initiation during AKI.

Influence of the Initial Neutrophils to Lymphocytes and Platelets Ratio on the Incidence and Severity of Sepsis-Associated Acute Kidney Injury: A Double Robust Estimation Based on a Large Public Database

Background

Acute kidney injury (AKI) is a frequent consequence of sepsis and has been linked to poor prognosis. In critically ill patients, the ratio of neutrophils to lymphocytes and platelets (N/LP) has been confirmed as an inflammation-related marker connected with the development of renal dysfunction. However, the effect of the N/LP ratio on the initiation and development of AKI in patients with sepsis remained unclear. The purpose of this study was to determine if the N/LP ratio on intensive care unit (ICU) admission was associated with the occurrence of sepsis-associated AKI (S-AKI) and severe AKI.

Methods

Adult septic patients from the Medical Information Mart for Intensive Care-IV database were screened and classified into three categories (low, middle, or high) based on their N/LP ratio quartiles. The Cox proportional hazard and competing risk models were used to determine the risk of S-AKI in various N/LP groups, whilst the logistic regression model and restricted cubic splines (RCS) analysis were employed to investigate the link between N/LP ratios and the occurrence of severe AKI. Finally, we did a doubly robust estimation, a subgroup analysis, and a sensitivity analysis to determine the findings’ robustness.

Results

We categorized 485, 968, and 485 septic patients into three groups based on their N/LP ratios: low, intermediate, and high. According the Cox proportional hazard model, the hazard rate (95% CI) for those in the middle and high N/LP groups on the incidence of S-AKI were 1.30(1.07, 1.58) and 1.27(1.02, 1.59), respectively, as compared to those in the low N/LP group. And the Fine-Gray proportional subdistribution hazards model indicated that mortality was not a substantial competing risk for S-AKI. Additionally, multivariate logistic regression revealed that the risk of severe AKI increased 1.83 fold in the high group compared to the low group. The RCS result also suggested that the probability of severe AKI rose significantly when N/LP > 9.5. The consistency of these findings was confirmed using doubly robust estimation. However, subgroup and sensitivity analyses revealed that the association between N/LP and the incidence of S-AKI, severe AKI varied considerably between different populations and diagnostic criteria.

Conclusion

A raised initial N/LP level may induce the development of S-AKI and severe AKI within 7 days after ICU admission in septic patients. These influences were enhanced in elder, male, septic shock, and those with poor health condition. Furthermore, high NLP was more strongly connected to the risk of S-AKI and severe AKI in sepsis patients on the urine output-based AKI criteria than on the serum creatinine-based criteria.

Small, short-term, point-of-care creatinine changes as predictors of acute kidney injury in critically ill patients

PURPOSE

To assess short-term creatinine changes as predictors of acute kidney injury (AKI) when used alone and in combination with AKI risk factors.

METHODS

In this prospective cohort study, we identified all creatinine measurements from frequent point-of-care arterial blood gas measurements from ICU admission until AKI. We evaluated the predictive value of small changes between these creatinine measurements for AKI development, alone and with AKI risk factors.

RESULTS

Of 377 patients with 3235 creatinine measurements, generating 15,075 creatinine change episodes, 215 (57%) patients developed AKI, and 68 (18%) developed stage 2 or 3 AKI. In isolation, a creatinine increase over 4.1-7.3 h had a 0.65 area under the curve for predicting stage 2 or 3 AKI within 3-37.7 h. Combining creatinine increases of ≥1 μmol/L/h (≥0.0113 mg/dL/h) over 4-5.8 h with three AKI risk factors (cardiac surgery, use of vasopressors, chronic liver disease) had 83% sensitivity, 79% specificity and 0.87 area under the curve for stage 2 or 3 AKI occurring 8.7-25.6 h later.

CONCLUSION

In combination with key risk factors, frequent point-of-care creatinine assessment on arterial blood gases to detect small, short-term creatinine changes provides a robust, novel, low-cost, and rapid method for predicting AKI in critically ill patients.

Serum cystatin C, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, klotho and fibroblast growth factor-23 in the early prediction of acute kidney injury associated with sepsis in a Chinese emergency cohort study

Background

Acute kidney injury (AKI) is a common and critical complication of sepsis, and is associated with unacceptable morbidity and mortality. Current diagnostic criteria for AKI was insensitive for early detection. Novel biomarkers including cystatin C, kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), klotho and fibroblast growth factor-23 (FGF-23) can predict AKI earlier and allow immediate interventions. We aimed to determine the diagnostic performance of these biomarkers for detecting AKI in sepsis patients.

Methods

This prospective observational study was conducted between May 2018 and November 2020, enrolling 162 sepsis patients eventually. The AKI was defined in accordance with 2012 KDIGO criteria and we divided patients into non-AKI (n = 102) and AKI (n = 60) groups. Serum levels of several AKI biomarkers were detected by ELISA. The relationship between biomarker levels on admission of AKI was analyzed and discrimination performances comparison were performed.

Results

AKI incidence was up to 37.0% (60/162) during hospitalization. Compared with non-AKI group, both serum cystatin C, KIM-1, NGAL and FGF-23 were significantly elevated at admission in septic AKI patients. The areas under the receiver operating curves demonstrated that serum cystatin C had modest discriminative powers for predicting AKI after sepsis, and cystatin C combined with serum creatinine in the prediction of septic AKI increased the diagnostic sensitivity prominently.

Conclusion

Serum cystatin C, KIM-1, NGAL and FGF-23 levels were both increased in septic AKI patients. Our study provided reliable evidence that cystatin C solely and combined with serum creatinine may accurately and sensitively predict septic AKI of patients on admission.

Gelatin and the risk of acute kidney injury after cardiac surgery

BACKGROUND

Gelatin has been used as a plasma volume expander because of its ability to preserve intravascular volume more effectively than crystalloids. However, gelatin may have detrimental effects on kidney function and increase the risk of acute kidney injury (AKI).

METHOD

We investigated by retrospective analysis of prospectively collected data whether the administration of 4% succinyl gelatin is associated with an increased risk of AKI after cardiac surgery. We compared two propensity score-matched groups of 1,187 patients (crystalloid group and gelatin group).

RESULTS

The incidence of AKI was similar in both groups (gelatin 21% and crystalloid 20%) (p = 0.414). The incidence of moderate AKI (8% vs. 6%) was higher in the gelatin group, but there was no difference in mild or severe AKI. Postoperative serum creatine on the first (70 vs. 70 μmol L^-1 , p = 0.689) or fourth (71 vs. 70, p = 0.313) postoperative day was similar between groups and there was no difference in the need for new renal replacement therapy (p = 0.999). Patients in the gelatin group received less crystalloids (2080 ml vs. 4130 ml, p = 0.001) and total fluids (3760 ml vs. 4180 ml, p = 0.001), their fluid balance was less positive (p = 0.001) and they required less vasoactive and inotropic medication (p = 0.001). Gelatin was not associated with increased mortality compared to the crystalloid group.

CONCLUSION

Gelatin was not associated with AKI after cardiac surgery.

A deep-learning model to continuously predict severe acute kidney injury based on urine output changes in critically ill patients

BACKGROUND

Acute Kidney Injury (AKI), a frequent complication of pateints in the Intensive Care Unit (ICU), is associated with a high mortality rate. Early prediction of AKI is essential in order to trigger the use of preventive care actions.

METHODS

The aim of this study was to ascertain the accuracy of two mathematical analysis models in obtaining a predictive score for AKI development. A deep learning model based on a urine output trends was compared with a logistic regression analysis for AKI prediction in stages 2 and 3 (defined as the simultaneous increase of serum creatinine and decrease of urine output, according to  the Acute Kidney Injury Network (AKIN) guidelines). Two retrospective datasets including 35,573 ICU patients were analyzed. Urine output data were used to train and test the logistic regression and the deep learning model.

RESULTS

The deep learning model defined an area under the curve (AUC) of 0.89 (± 0.01), sensitivity = 0.8 and specificity = 0.84, which was higher than the logistic regression analysis. The deep learning model was able to predict 88% of AKI cases more than 12 h before their onset: for every 6 patients identified as being at risk of AKI by the deep learning model, 5 experienced the event. On the contrary, for every 12 patients not considered to be at risk by the model, 2 developed AKI.

CONCLUSION

In conclusion, by using urine output trends, deep learning analysis was able to predict AKI episodes more than 12 h in advance, and with a higher accuracy than the classical urine output thresholds. We suggest that this algorithm could be integrated in the ICU setting to better manage, and potentially prevent, AKI episodes.

Association of Oliguria With Acute Kidney Injury Diagnosis, Severity Assessment, and Mortality Among Patients With Critical Illness

Importance

The current definition and staging of acute kidney injury (AKI) considers alterations in serum creatinine (sCr) level and urinary output (UO). However, the relevance of oliguria-based criteria is disputed.

Objective

To determine the contribution of oliguria, as defined by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria, to AKI diagnosis, severity assessment, and short- and long-term outcomes.

Design, Setting, and Participants

This cohort study included adult patients admitted to a multidisciplinary intensive care unit from January 1, 2010, to June 15, 2020. Patients receiving long-term dialysis and those who declined consent were excluded. Daily sCr level and hourly UO measurements along with sociodemographic characteristics and severity scores were extracted from electronic medical records. Long-term mortality was assessed by cross-referencing the database with the Swiss national death registry. The onset and severity of AKI according to the KDIGO classification was determined using UO and sCr criteria separately, and their agreement was assessed.

Main Outcomes and Measures

Using a multivariable model accounting for baseline characteristics, severity scores, and sCr stages, the association of UO criteria with 90-day mortality was evaluated. Sensitivity analyses were conducted to assess how missing sCr, body weight, and UO values, as well as different sCr baseline definitions and imputations methods, would affect the main results.

Results

Among the 15 620 patients included in the study (10 330 men [66.1%] with a median age of 65 [IQR, 53-75] years, a median Simplified Acute Physiology Score II score of 40.0 [IQR, 30.0-53.0], and a median follow-up of 67.0 [IQR, 34.0-100.0] months), 12 143 (77.7%) fulfilled AKI criteria. Serum creatinine and UO criteria had poor agreement on AKI diagnosis and staging (Cohen weighted κ, 0.36; 95% CI, 0.35-0.37; P < .001). Compared with the isolated use of sCr criteria, consideration of UO criteria enabled identification of AKI in 5630 patients (36.0%). Those patients had a higher 90-day mortality than patients without AKI (724 of 5608 [12.9%] vs 288 of 3462 [8.3%]; P < .001). On multivariable analysis accounting for sCr stage, comorbidities, and illness severity, UO stages 2 and 3 were associated with a higher 90-day mortality (odds ratios, 2.4 [95% CI, 1.6-3.8; P < .001] and 6.2 [95% CI, 3.7-10.5; P < .001], respectively). These results remained significant in all sensitivity analyses.

Conclusions and Relevance

The findings of this cohort study suggest that oliguria lasting more than 12 hours (KDIGO stage 2 or 3) has major AKI diagnostic implications and is associated with outcomes irrespective of sCr elevations.

Acute kidney injury detection using refined and physiological-feature augmented urine output

Acute kidney injury (AKI) is common in the intensive care unit, where it is associated with increased mortality. AKI is often defined using creatinine and urine output criteria. The creatinine-based definition is more reliable but less expedient, whereas the urine output based definition is rapid but less reliable. Our goal is to examine the urine output criterion and augment it with physiological features for better agreement with creatinine-based definitions of AKI. The objectives are threefold: (1) to characterize the baseline agreement of urine output and creatinine definitions of AKI; (2) to refine the urine output criteria to identify the thresholds that best agree with the creatinine-based definition; and (3) to build generalized estimating equation (GEE) and generalized linear mixed-effects (GLME) models with static and time-varying features to improve the accuracy of a near-real-time marker for AKI. We performed a retrospective observational study using data from two independent critical care databases, MIMIC-III and eICU, for critically ill patients who developed AKI in intensive care units. We found that the conventional urine output criterion (6 hr, 0.5 ml/kg/h) has specificity and sensitivity of 0.49 and 0.54 for MIMIC-III database; and specificity and sensitivity of 0.38 and 0.56 for eICU. Secondly, urine output thresholds of 12 hours and 0.6 ml/kg/h have specificity and sensitivity of 0.58 and 0.48 for MIMIC-III; and urine output thresholds of 10 hours and 0.6 ml/kg/h have specificity and sensitivity of 0.49 and 0.48 for eICU. Thirdly, the GEE model of four hours duration augmented with static and time-varying features can achieve a specificity and sensitivity of 0.66 and 0.61 for MIMIC-III; and specificity and sensitivity of 0.66 and 0.64 for eICU. The GLME model of four hours duration augmented with static and time-varying features can achieve a specificity and sensitivity of 0.71 and 0.55 for MIMIC-III; and specificity and sensitivity of 0.66 and 0.60 for eICU. The GEE model has greater performance than the GLME model, however, the GLME model is more reflective of the variables as fixed effects or random effects. The significant improvement in performance, relative to current definitions, when augmenting with patient features, suggest the need of incorporating these features when detecting disease onset and modeling at window-level rather than patient-level.

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

Background

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

Study goal

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

Methods

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

Results

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

Conclusion

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

Conceptual advances and evolving terminology in acute kidney disease

Over the past decade, new insights into epidemiology, pathophysiology and biomarkers have modified our understanding of acute kidney dysfunction and damage, and their association with subsequent chronic kidney disease. The concept of acute kidney injury (AKI), which has relied on established but nonetheless flawed biomarkers of solute clearance (serum creatinine levels and urinary output), has been challenged by the identification of novel biomarkers of tubular stress and/or damage. The expression of some of these novel biomarkers precedes changes in conventional biomarkers or can increase their predictive power, and might therefore enhance the clinical accuracy of the definition of AKI. In addition, the need to consider AKI recurrence, duration and progression to chronic kidney disease within the clinical and epidemiological framework of AKI led to the emergence of the concept of acute kidney disease. New definitions of acute syndromes of kidney impairment and injury are needed.

Preoperative renal malperfusion is an independent predictor for acute kidney injury and operative death but not associated with late mortality after surgery for acute type A aortic dissection

OBJECTIVES

This study was aimed to investigate the impact of preoperative renal malperfusion on early and late outcomes after surgery for acute type A aortic dissection (AAAD).

METHODS

Of 915 patients who underwent surgery for AAAD between September 2004 and September 2017, we enrolled 534 patients whose preoperative enhanced computed tomography images were retrospectively available in this study. Exclusion criteria were single kidney (n = 3) and dialysis-dependent preoperatively (n = 12). We compared early and late outcomes between patients who had preoperative renal malperfusion (n = 64) and those who did not have renal malperfusion (n = 470).

RESULTS

The incidence of postoperative acute kidney injury, defined using the Kidney Disease: Improving Global Outcomes criteria, was higher in the renal malperfusion group than in the no renal malperfusion group (76.6% vs 39.4%; P < 0.001). Similarly, operative death was more frequently seen in the renal malperfusion group (12.5% vs 3.8%; P = 0.003). Multivariate analyses showed that renal malperfusion was the independent predictor for postoperative acute kidney injury [odds ratio 4.32, 95% confidence interval (CI) 2.25-8.67; P < 0.001] and operative death (odds ratio 3.08, 95% CI 1.02-8.86; P = 0.046). The median follow-up period in the hospital survivors was 3.3 years (interquartile range 2.1-6.7 years). The cumulative survival rate at 8 years was similar between the groups (74.6% in the renal malperfusion group and 76.0% in the no renal malperfusion group; P = 0.349).

CONCLUSIONS

Preoperative renal malperfusion is an independent predictor for postoperative acute kidney injury and operative death but not associated with late mortality after surgery for acute type A aortic dissection.

Sepsis-Associated Acute Kidney Injury

Sepsis-associated acute kidney injury (S-AKI) is a common and life-threatening complication in hospitalized and critically ill patients. It is characterized by rapid deterioration of renal function associated with sepsis. The pathophysiology of S-AKI remains incompletely understood, so most therapies remain reactive and nonspecific. Possible pathogenic mechanisms to explain S-AKI include microcirculatory dysfunction, a dysregulated inflammatory response, and cellular metabolic reprogramming. In addition, several biomarkers have been developed in an attempt to improve diagnostic sensitivity and specificity of S-AKI. This article discusses the current understanding of S-AKI, recent advances in pathophysiology and biomarker development, and current preventive and therapeutic approaches.

An evaluation of sepsis in dentistry

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. It is a major health concern and causes substantial morbidity and mortality. It is imperative that the signs of sepsis are identified early in both adult and paediatric patients and appropriately escalated to initiate early treatment and improve prognosis. This paper aims to discuss the change in classification from the previous systemic inflammatory response syndrome (SIRS) criteria to the current definition in adults and also the unchanged definition in children. The hallmark signs of sepsis (both red and amber flags) are discussed in relation to their underlying cellular mechanisms to provide a comprehensive overview for clinicians in primary care, hospital and community settings. The rise of antimicrobial resistance is also an increasing global health concern with resistant bacteria from common infections likely to result in greater patient morbidity and worse outcomes.A literature search identified reported sepsis cases in dentistry through searches in Ovid Medline and Embase from January 1990 to December 2019. Only primary studies were included with no restrictions on languages. Four articles were identified which reported sepsis associated with tooth extractions, dental abscess and submental/submandibular cellulitis. It is well known that locoregional infections of dental origin have the potential to cause sepsis. Therefore, dental healthcare professionals need to be vigilant and understand the specific signs and escalation protocols to ensure patient safety.

Intraoperative oliguria does not predict postoperative acute kidney injury in major abdominal surgery: a cohort analysis

BACKGROUND

Acute kidney injury (AKI) is a common complication in patients undergoing major abdominal surgery and is associated with considerable morbidity and mortality. Several studies investigating the association between intraoperative urine output and postoperative AKI have shown conflicting results. Here, we investigated the association of intraoperative oliguria with postoperative AKI in a cohort of patients submitted to elective major abdominal surgery.

METHODS

This was a single-center retrospective analysis of adult patients who underwent elective major abdominal surgery from January 2016 to December 2018. AKI was defined according to the serum creatinine criteria of the KDIGO classification. Intraoperative oliguria was defined as urine output of less than 0.5 mL/kg/h. Risk factors were evaluated using multivariate logistic regression analysis.

RESULTS

A total of 165 patients were analyzed. In the first 48 h after surgery the incidence of AKI was 19.4%. Postoperative AKI was associated with hospital mortality (p=0.011). Twenty percent of patients developed intraoperative oliguria. There was no association between preexisting comorbidities and development of intraoperative oliguria. There was no correlation between the type of anesthesia used and occurrence of intraoperative oliguria, but longer anesthesia time was associated with intraoperative oliguria (p=0.007). Higher baseline SCr (p=0.001), need of vasoactive drugs (p=0.007), and NSAIDs use (p=0.022) were associated with development of intraoperative oliguria. Intraoperative oliguria was not associated with development of postoperative AKI (p=0.772), prolonged hospital stays (p=0.176) or in-hospital mortality (p=0.820).

CONCLUSION

In this cohort of patients we demonstrated that intraoperative oliguria does not predict postoperative AKI in major abdominal surgery.

Risk prediction for severe acute kidney injury by integration of urine output, glomerular filtration, and urinary cell cycle arrest biomarkers

BACKGROUND

Frequent assessment of urine output (UO), serum creatinine (sCr) and urinary cell cycle arrest biomarkers (CCAB) may improve acute kidney injury (AKI) prediction.

OBJECTIVE

To study the performance of UO, short term sCr changes and urinary CCAB to predict severe AKI.

METHODS

We measured 6 hours of UO, 6-hourly sCr changes, and urinary CCABs in all critically ill patients with cardiovascular or respiratory failure or early signs of renal stress between February and October 2018. We studied the association of such measurements, and their combination, with the development of AKI Stage 2 or 3 of the Kidney Disease: Improving Global Outcomes (KDIGO) definition at 12 hours. We evaluated predictive performance with logistic regression, area under the receiver operating characteristic (AUROC) curve, and net reclassification indices. We computed an optimal cut-off value for each biomarker.

RESULTS

We assessed 622 patients and, as per the exclusion criteria, we enrolled 105 critically ill patients. After 12 hours of enrolment, AKI occurred in 32 patients (30%). UO, sCr change over 6 hours and CCABs were significantly associated with severe AKI at 12 hours, with all variables achieving an AUROC > 0.7 after adjustment. Combination of any of the two or three variables achieved an AUROC > 0.7 for subsequent severe AKI at 12 hours. The optimal predictive high specificity cut-off values were ≤ 0.4 mL/kg/h for UO, variation of +15 μmol/L over 6 hours in sCr, and ≥ 1.5 (ng/mL)2/1000 for CCABs.

CONCLUSION

In this prospective study, an integrative approach using UO, short term sCr change and/or urinary CCABs showed a satisfactory performance for the prediction of severe AKI development at 12 hours.

The clinical relevance of oliguria in the critically ill patient: analysis of a large observational database

BACKGROUND

Urine output is widely used as one of the criteria for the diagnosis and staging of acute renal failure, but few studies have specifically assessed the role of oliguria as a marker of acute renal failure or outcomes in general intensive care unit (ICU) patients. Using a large multinational database, we therefore evaluated the occurrence of oliguria (defined as a urine output < 0.5 ml/kg/h) in acutely ill patients and its association with the need for renal replacement therapy (RRT) and outcome.

METHODS

International observational study. All adult (> 16 years) patients in the ICON audit who had a urine output measurement on the day of admission were included. To investigate the association between oliguria and mortality, we used a multilevel analysis.

RESULTS

Of the 8292 patients included, 2050 (24.7%) were oliguric during the first 24 h of admission. Patients with oliguria on admission who had at least one additional 24-h urine output recorded during their ICU stay (n = 1349) were divided into three groups: transient-oliguria resolved within 48 h after the admission day (n = 390 [28.9%]), prolonged-oliguria resolved > 48 h after the admission day (n = 141 [10.5%]), and permanent-oliguria persisting for the whole ICU stay or again present at the end of the ICU stay (n = 818 [60.6%]). ICU and hospital mortality rates were higher in patients with oliguria than in those without, except for patients with transient oliguria who had significantly lower mortality rates than non-oliguric patients. In multilevel analysis, the need for RRT was associated with a significantly higher risk of death (OR = 1.51 [95% CI 1.19-1.91], p = 0.001), but the presence of oliguria on admission was not (OR = 1.14 [95% CI 0.97-1.34], p = 0.103).

CONCLUSIONS

Oliguria is common in ICU patients and may have a relatively benign nature if only transient. The duration of oliguria and need for RRT are associated with worse outcome.

Reversibility of Acute Kidney Injury in Medical ICU Patients: Predictability Performance of Urinary Tissue Inhibitor of Metalloproteinase-2 x Insulin-Like Growth Factor-Binding Protein 7 and Renal Resistive Index

OBJECTIVES

Urinary biomarkers and renal Doppler sonography remain considered as promising tools to distinguish transient from persistent acute kidney injury. The performance of the urinary biomarker, tissue inhibitor of metalloproteinase-2 x insulin-like growth factor-binding protein 7 and of renal resistive index to predict persistent acute kidney injury showed contradictory results. Our aim was to evaluate the performance of tissue inhibitor of metalloproteinase-2 x insulin-like growth factor-binding protein 7 and renal resistive index in predicting reversibility of acute kidney injury in critically ill patients.

DESIGN

Prospective observational study.

SETTING

Twenty-bed medical ICU in an university hospital.

PATIENTS

Consecutive patients with acute kidney injury.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Renal resistive index was measured within 12 hours after admission, and urinary tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7 was measured at H0, H6, H12, and H24. Renal dysfunction reversibility was evaluated at day 3. Receiver operating characteristic curves were plotted to evaluate diagnostic performance of renal resistive index and tissue inhibitor of metalloproteinase-2 x insulin-like growth factor-binding protein 7 to predict a persistent acute kidney injury. Overall, 100 patients were included in whom 50 with persistent acute kidney injury. Renal resistive index was higher in persistent acute kidney injury group. Urinary tissue inhibitor of metalloproteinase-2 x insulin-like growth factor-binding protein 7 was not significantly different at each time between both groups. The performance of tissue inhibitor of metalloproteinase-2 x insulin-like growth factor-binding protein 7 was poor with respectively an area under the receiver operating characteristic curves of 0.57 (95% CI, 0.45-0.68), 0.58 (95% CI, 0.47-0.69), 0.61 (95% CI, 0.50-0.72), and 0.57 (95% CI, 0.46-0.68) at H0, H6, H12, and H24. The area under the receiver operating characteristic curve for renal resistive index was 0.93 (95% CI, 0.89-0.98). A renal resistive index greater than or equal to 0.685 predicting persistent acute kidney injury with 78% (95% CI, 64-88%) sensitivity and 90% (95% CI, 78-97%) specificity.

CONCLUSIONS

Renal resistive index had a good performance for predicting the reversibility of acute kidney injury in critically ill patients. Urinary tissue inhibitor of metalloproteinase-2 x insulin-like growth factor-binding protein 7 was unable to differentiate transient from persistent acute kidney injury.

Current understanding and future directions in the application of TIMP-2 and IGFBP7 in AKI clinical practice

NephroCheck® is the commercial name of a combined product of two urinary biomarkers, tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7), expressed as [TIMP-2]·[IGFBP7], used to identify patients at high risk of acute kidney injury (AKI). AKI is a common and harmful complication especially in critically-ill patients, which can induce devastating short- and long-term outcomes. Over the past decade, numerous clinical studies have evaluated the utility of several biomarkers (e.g. neutrophil gelatinase-associated lipocalin, interleukin-18, liver-type fatty acid binding protein and kidney injury molecule-1, cystatin C) in the early diagnosis and risk stratification of AKI. Among all these biomarkers, [TIMP-2]·[IGFBP7] was confirmed to be superior in early detection of AKI, before the decrease of renal function is evident. In 2014, the US Food and Drug Administration permitted marketing of NephroCheck® (Astute Medical) (measuring urinary [TIMP-2]·[IGFBP7]) to determine if certain critically-ill patients are at risk of developing moderate to severe AKI. It has since been applied to clinical work in many hospitals of the United States and Europe to improve the diagnostic accuracy and outcomes of AKI patients. Now, more and more research is devoted to the evaluation of its application value, meaning and method in different clinical settings. In this review, we summarize the current research status of [TIMP-2]·[IGFBP7] and point out its future directions.

Bisphenol A co-exposure effects: a key factor in understanding BPA's complex mechanism and health outcomes

Bisphenol A (BPA) is an environmental endocrine disrupting chemical widely used in the production of consumer products, such as polycarbonate plastics, epoxies, and thermal receipt paper. Human exposure to BPA is ubiquitous due to its high-volume production and use. BPA exposure has been associated with obesity, diabetes, reproductive disorders, and cancer. Yet, the molecular mechanisms or modes of action underlying these disease outcomes are poorly understood due to the pleiotropic effects induced by BPA. A further confounding factor in understanding BPA's impact on human health is that co-exposure of BPA with endogenous and exogenous agents occurs during the course of daily life. Studies investigating BPA exposure effects and their relationship to adverse health outcomes often ignore interactions between BPA and other chemicals present in the environment. This review examines BPA co-exposure studies to highlight potentially unexplored mechanisms of action and their possible associations with the adverse health effects attributed to BPA. Importantly, both adverse and beneficial co-exposure effects are observed between BPA and natural chemicals or environmental stressors in in vitro and in vivo models. These interactions clearly influence cellular responses and impact endpoint measures and need to be considered when evaluating BPA exposures and their health effects.

Acute kidney injury from sepsis: current concepts, epidemiology, pathophysiology, prevention and treatment

Sepsis-associated acute kidney injury (S-AKI) is a frequent complication of the critically ill patient and is associated with unacceptable morbidity and mortality. Prevention of S-AKI is difficult because by the time patients seek medical attention, most have already developed acute kidney injury. Thus, early recognition is crucial to provide supportive treatment and limit further insults. Current diagnostic criteria for acute kidney injury has limited early detection; however, novel biomarkers of kidney stress and damage have been recently validated for risk prediction and early diagnosis of acute kidney injury in the setting of sepsis. Recent evidence shows that microvascular dysfunction, inflammation, and metabolic reprogramming are 3 fundamental mechanisms that may play a role in the development of S-AKI. However, more mechanistic studies are needed to better understand the convoluted pathophysiology of S-AKI and to translate these findings into potential treatment strategies and add to the promising pharmacologic approaches being developed and tested in clinical trials.

Urinary neutrophil gelatinase-associated lipocalin as a biomarker of acute kidney injury in sepsis patients in the emergency department

BACKGROUND

Plasma neutrophil gelatinase-associated lipocalin (NGAL) is a useful biomarker for predicting acute kidney injury (AKI). The purpose of this study was to evaluate the diagnostic performance of urinary NGAL in predicting AKI in sepsis patients in the emergency department.

METHODS

A total of 140 patients were enrolled. We compared serum procalcitonin and urinary NGAL concentrations between patients with local infection, sepsis, and septic shock, and between patients who did and did not develop AKI with sepsis. Receiver-operating characteristic curve analysis was used to evaluate the ability to predict AKI in sepsis patients.

RESULTS

Both serum procalcitonin and urinary NGAL concentrations were significantly higher in the sepsis and septic shock groups than in the local infection group (both p < 0.001). In sepsis patients, serum procalcitonin and urinary NGAL concentrations were higher in AKI patients than in those without AKI (p = 0.006, p < 0.001, respectively). The area under the curve for predicting of AKI was higher for a urinary NGAL of 0.820 (95% confidence interval (CI) 0.721-0.895) than for a serum procalcitonin concentration of 0.76 (95% CI 0.597-0.800).

CONCLUSION

Urinary NGAL concentration may predict AKI in patients with sepsis in the emergency department.

Furosemide as a functional marker of acute kidney injury in ICU patients: a new role for an old drug

New pharmacokinetics insight suggests that the furosemide pharmacology occurring in ICU patients with AKI is similar, but not equal to that described in chronic stable renal patients. Even if the diuretic response to furosemide is expressed by a steep dose-response curve positively correlated with renal function, pharmacodynamic limitations occur when creatinine clearance is < 20 ml/min or urine output is < 500 ml/12 h. In such cases, other factors specifically due to acute tubular injury can interfere with the furosemide-induced diuretic output. As modality of administration recent reports and metanalysis, even if not conclusive, suggest that for the same given dose a continuous infusion of furosemide was superior in diuretic response. For septic shock patients on CVVHDF where treatment adds an additional clearance of furosemide the maximum diuretic response is achieved by a continuous infusion of 20 mg/h of furosemide. At this infusion rate the reached plasma level was < 20 mg/L, a range considered safe and not ototoxic. Therefore, the severity of AKI establishes whether a patient will respond to furosemide. In this review we summarized all these recent updates, also suggesting that the diuretic response under continuous infusion may allow assessing glomerular and tubular functions with increased reliability than a bolus dose. However, validation studies are still needed to support continuous infusion as a stress test.

Early prediction of acute kidney injury following ICU admission using a multivariate panel of physiological measurements

BACKGROUND

The development of acute kidney injury (AKI) during an intensive care unit (ICU) admission is associated with increased morbidity and mortality.

METHODS

Our objective was to develop and validate a data driven multivariable clinical predictive model for early detection of AKI among a large cohort of adult critical care patients. We utilized data form the Medical Information Mart for Intensive Care III (MIMIC-III) for all patients who had a creatinine measured for 3 days following ICU admission and excluded patients with pre-existing condition of Chronic Kidney Disease and Acute Kidney Injury on admission. Data extracted included patient age, gender, ethnicity, creatinine, other vital signs and lab values during the first day of ICU admission, whether the patient was mechanically ventilated during the first day of ICU admission, and the hourly rate of urine output during the first day of ICU admission.

RESULTS

Utilizing the demographics, the clinical data and the laboratory test measurements from Day 1 of ICU admission, we accurately predicted max serum creatinine level during Day 2 and Day 3 with a root mean square error of 0.224 mg/dL. We demonstrated that using machine learning models (multivariate logistic regression, random forest and artificial neural networks) with demographics and physiologic features can predict AKI onset as defined by the current clinical guideline with a competitive AUC (mean AUC 0.783 by our all-feature, logistic-regression model), while previous models aimed at more specific patient cohorts.

CONCLUSIONS

Experimental results suggest that our model has the potential to assist clinicians in identifying patients at greater risk of new onset of AKI in critical care setting. Prospective trials with independent model training and external validation cohorts are needed to further evaluate the clinical utility of this approach and potentially instituting interventions to decrease the likelihood of developing AKI.

Performance of Doppler-based resistive index and semi-quantitative renal perfusion in predicting persistent AKI: results of a prospective multicenter study

PURPOSE

The Doppler-based resistive index (RI) and semi-quantitative evaluation of renal perfusion using color Doppler (SQP) have shown promising results for predicting persistent acute kidney injury (AKI) in preliminary studies. This study aimed at evaluating the performance of RI and SQP to predict short-term renal prognosis in critically ill patients.

METHODS

Prospective multicenter cohort study including unselected critically ill patients. Renal Doppler was performed at admission to the intensive care unit. The diagnostic performance of RI and SQP to predict persistent AKI at day 3 was evaluated.

RESULTS

Overall, 371 patients were included, of whom 351 could be assessed for short-term renal recovery. Two thirds of the included patients had AKI (n = 233; 66.3%), of whom 136 had persistent AKI (58.4%). Doppler-based RI was higher and SQP lower in AKI patients and according to AKI recovery. Overall performance in predicting persistent AKI was however poor with area under ROC curve of respectively 0.58 (95% CI 0.52-0.64) and 0.59 (95% CI 0.54-0.65) for RI and SQP. Optimal cutoff was respectively 0.71 and 2 for RI and SQP. At optimal cutoff, sensitivity and specificity were 50% (95% CI 41-58%) and 68% (62-74%) for RI and 39% (32-45%) and 75% (66-82%) for SQP.

CONCLUSION

Although statistically associated with AKI occurrence, RI and SQP perform poorly in predicting persistent AKI at day 3. Further studies are needed to adequately describe factors influencing Doppler-based assessment of renal perfusion and to delineate whether these indicators may be useful at the bedside. CLINICALTRIAL.GOV: NCT02355314.

Oliguria in critically ill patients: a narrative review

Oliguria is often observed in critically ill patients. However, different thresholds in urine output (UO) have raised discussion as to the clinical importance of a transiently reduced UO of less than 0.5 ml/kg/h lasting for at least 6 h. While some studies have demonstrated that isolated oliguria without a concomitant increase in serum creatinine is associated with higher mortality rates, different underlying pathophysiological mechanisms suggest varied clinical importance of reduced UO, as some episodes of oliguria may be fully reversible. We aim to explore the clinical relevance of oliguria in critically ill patients and propose a clinical pathway for the diagnostic and therapeutic management of an oliguric, critically ill patient.

Early postoperative change in serum creatinine predicts acute kidney injury after cardiothoracic surgery: a retrospective cohort study

BACKGROUND

Acute kidney injury (AKI) is one of the most severe complications after cardiothoracic surgery (CTS). However, diagnosis of AKI by elevation of serum creatinine (SCr) misses a critical time period for prevention and treatment of AKI. We have observed that patients who develop AKI show a smaller SCr decrease after CTS than those without AKI. Hence, we hypothesized that the magnitude of the SCr change (ΔSCr) measured early after CTS can predict subsequent AKI.

METHODS

We conducted a retrospective analysis from January 2014 to December 2016 to examine the association of ΔSCr with AKI. ΔSCr was calculated as follows: (early postoperative SCr on intensive care unit [ICU] admission) - (preoperative SCr). Established risk factors and demographics were included in the multivariate-adjusted logistic regression model. AKI was defined by SCr criteria of the Kidney Disease: Improving Global Outcomes group.

RESULTS

Among 252 patients who underwent CTS, 69 developed AKI. The median ΔSCr was - 0.14 mg/dL (range - 0.96-0.45). Patients were divided into three groups based on ΔSCr: Group 1, ≤ - 0.2 mg/dL (n = 84); Group 2, > - 0.2 to < - 0.1 mg/dL (n = 76); and Group 3, ≥ - 0.1 mg/dL (n = 92). In the multivariate analysis, Group 3 had a significantly higher incidence of AKI than Group 1 (odds ratio, 7.34; 95% confidence interval 2.55-23.3). ΔSCr was an independent risk factor for AKI (odds ratio for every 0.1-mg/dL increase in ΔSCr, 1.55; 95% confidence interval 1.23-1.97).

CONCLUSIONS

A minor change in the SCr level early after CTS can predict subsequent AKI just after ICU admission.

Renal Angina Is a Sensitive, but Nonspecific Identifier of Postcardiac Surgery Acute Kidney Injury

OBJECTIVES

Acute kidney injury (AKI) is a common complication of cardiac surgery, and early detection is difficult. This study was performed to determine the sensitivity, specificity, positive predictive value, negative predictive value, and statistical performance of renal angina (RA) as an early predictor of AKI in an adult cardiac surgical patient population.

DESIGN

Retrospective, nonrandomized, observational study.

SETTING

A single, university-affiliated, quaternary medical center.

PARTICIPANTS

The study comprised 324 consecutive patients undergoing coronary artery bypass grafting or cardiac valvular surgery from February 1 through July 30, 2014.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred-seven patients at moderate or high risk of developing postoperative renal injury were identified, 82 of whom met criteria for RA. The occurrence of RA was found to have an 80.9% sensitivity and 30.8% specificity for the prediction of AKI using Acute Kidney Injury Network criteria and 89.3% sensitivity and 27.8% specificity when paired with the Risk, Injury, Failure, Loss, End Stage Renal Disease criteria. A receiver operating characteristic area under the curve analysis revealed a nonsignificant predictive ability of 55.8% (95% confidence interval 0.47-0.65) when RA was paired with Acute Kidney Injury Network criteria; however, the receiver operating characteristic area under the curve was significant when paired with Risk, Injury, Failure, Loss, End Stage Renal Disease criteria, with a predictive ability of 0.586 (0.509-0.662).

CONCLUSIONS

RA is a sensitive, but nonspecific, predictor of postcardiac surgery AKI, with clinical utility most suited as a screening tool.

Urinary Biochemistry in the Diagnosis of Acute Kidney Injury

Acute kidney injury (AKI) is a common complication, impacting short- and long-term patient outcomes. Although the application of the classification systems for AKI has improved diagnosis, early clinical recognition of AKI is still challenging, as increments in serum creatinine may be late and low urine output is not always present. The role of urinary biochemistry has remained unclear, especially in critically ill patients. Differentiating between a transient and persistent acute kidney injury is of great need in clinical practice, and despite studies questioning their application in clinical practice, biochemistry indices continue to be used while we wait for a novel early injury biomarker. An ideal marker would provide more detailed information about the type, intensity, and location of the injury. In this review, we will discuss factors affecting the fractional excretion of sodium (FeNa) and fractional excretion of urea (FeU). We believe that the frequent assessment of urinary biochemistry and microscopy can be useful in evaluating the likelihood of AKI reversibility. The availability of early injury biomarkers could help guide clinical interventions.

Fluid balance-adjusted creatinine at initiation of continuous venovenous hemofiltration and mortality. A post-hoc analysis of a multicenter randomized controlled trial

INTRODUCTION

Acute kidney injury (AKI) requiring renal replacement therapy (RRT) is associated with high mortality. The creatinine-based stage of AKI is considered when deciding to start or delay RRT. However, creatinine is not only determined by renal function (excretion), but also by dilution (fluid balance) and creatinine generation (muscle mass). The aim of this study was to explore whether fluid balance-adjusted creatinine at initiation of RRT is related to 28-day mortality independent of other markers of AKI, surrogates of muscle mass and severity of disease.

METHODS

We performed a post-hoc analysis on data from the multicentre CASH trial comparing citrate to heparin anticoagulation during continuous venovenous hemofiltration (CVVH). To determine whether fluid balance-adjusted creatinine was associated with 28-day mortality, we performed a logistic regression analysis adjusting for confounders of creatinine generation (age, gender, body weight), other markers of AKI (creatinine, urine output) and severity of disease.

RESULTS

Of the 139 patients, 32 patients were excluded. Of the 107 included patients, 36 died at 28 days (34%). Non-survivors were older, had higher APACHE II and inclusion SOFA scores, lower pH and bicarbonate, lower creatinine and fluid balance-adjusted creatinine at CVVH initiation. In multivariate analysis lower fluid balance-adjusted creatinine (OR 0.996, 95% CI 0.993-0.999, p = 0.019), but not unadjusted creatinine, remained associated with 28-day mortality together with bicarbonate (OR 0.869, 95% CI 0.769-0.982, P = 0.024), while the APACHE II score non-significantly contributed to the model.

CONCLUSION

In this post-hoc analysis of a multicentre trial, low fluid balance-adjusted creatinine at CVVH initiation was associated with 28-day mortality, independent of other markers of AKI, organ failure, and surrogates of muscle mass, while unadjusted creatinine was not. More tools are needed for better understanding of the complex determinants of "AKI classification", "CVVH initiation" and their relation with mortality, fluid balance is only one.

Clinical Relevance and Predictive Value of Damage Biomarkers of Drug-Induced Kidney Injury

Nephrotoxin exposure accounts for up to one-fourth of acute kidney injury episodes in hospitalized patients, and the associated consequences are as severe as acute kidney injury due to other etiologies. As the use of nephrotoxic agents represents one of the few modifiable risk factors for acute kidney injury, clinicians must be able to identify patients at high risk for drug-induced kidney injury rapidly. Recently, significant advancements have been made in the field of biomarker utilization for the prediction and detection of acute kidney injury. Such biomarkers may have a role both for detection of drug-induced kidney disease and implementation of preventative and therapeutic strategies designed to mitigate injury. In this article, basic principles of renal biomarker use in practice are summarized, and the existing evidence for six markers specifically used to detect drug-induced kidney injury are outlined, including liver-type fatty acid binding protein, neutrophil gelatinase-associated lipocalin, tissue inhibitor of metalloproteinase-2 times insulin-like growth factor-binding protein 7 ([TIMP-2]·[IGFBP7]), kidney injury molecule-1 and N-acetyl-β-D-glucosaminidase. The results of the literature search for these six kidney damage biomarkers identified 29 unique articles with none detected for liver-type fatty acid binding protein and [TIMP-2]·[IGFBP7]. For three biomarkers, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin and N-acetyl-β-D-glucosaminidase, the majority of the studies suggest utility in clinical practice. While many questions need to be answered to clearly articulate the use of biomarkers to predict drug-induced kidney disease, current data are promising.