Early detection of acute renal failure by serum cystatin C

Utility of cystatin C-based equations in patients undergoing dialysis

Serum cystatin C (CysC) measurement is regarded as a simple and practical alternative to measure residual renal function for dialysis patients. Recent studies have shown that CysC has better diagnostic accuracy or at least equivalence to creatinine in predicting the early stages of renal damage, and is closely related to clinical outcomes of dialysis patients. Thus, the applicability of CysC-derived equations in patients undergoing dialysis should be paid attention. Here, we review the role of CysC in diagnosis, renal function evaluation, and prognosis outcomes for dialysis patients, so as to provide them with useful suggestions on evaluating renal function and predicting adverse outcomes in clinical practice.

Acute kidney injury and mild therapeutic hypothermia in patients after cardiopulmonary resuscitation - a post hoc analysis of a prospective observational trial

Background

The aim of this study was to investigate the influence of mild therapeutic hypothermia (MTH) on the incidence of and recovery from acute kidney injury (AKI).

Methods

Patients who had undergone successful cardiopulmonary resuscitation (CPR) were included. Serum creatinine and cystatin C were measured at baseline, daily up to 5 days and at ICU discharge. AKI was defined by the Kidney Disease Improving Global Outcomes (KDIGO) criteria. MTH was applied for 24 h targeting a temperature of 33 °C. Neurological outcome was assessed with the Cerebral Performance Categories score at hospital discharge.

Results

126 patients were included in the study; 73 patients (58%) developed AKI. Patients treated with MTH had a significantly lower incidence of AKI as compared to normothermia (NT) (44 vs. 69%; p = 0.004). Patients with less favourable neurological outcomes had a significantly higher rate of AKI, although when treated with MTH the occurrence of AKI was reduced (50 vs. 80%; p = 0.017). Furthermore, MTH treatment was accompanied by significantly lower creatinine levels on day 0–1 and at ICU discharge (day 0: 1.12 (0.90–1.29) vs. 1.29 (1.00–1.52) mg/dl; p = 0.016) and lower cystatin C levels on day 0–3 and at ICU discharge (day 0: 0.88 (0.77–1.10) vs. 1.29 (1.06–2.16) mg/l; p < 0.001).

Conclusions

Mild therapeutic hypothermia seems to have a protective effect against the development of AKI and on renal recovery. This may be less pronounced in patients with a favourable neurological outcome.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2061-6) contains supplementary material, which is available to authorized users.

Evaluation of the effect of Retrograde Intrarenal Surgery with Myo-Inositol Oxygenase

Objective:

To investigate the effect of retrograde intra-renal surgery (RIRS) on kidneys using the myo-inositol oxygenase (MIOX) enzyme. MIOX is a renal tubular-specific novel marker for the early diagnosis of acute kidney injury.

Methods:

A total of twenty seven individuals that had undergone RIRS to treat kidney stones were included in the study. Biochemical tests were performed on serum samples collected immediately before RIRS (hour 0) and at the 6th and 24th hours after the surgery.

Results:

The creatinine value at hour 6 was lower than the baseline (hour 0) value (p = 0.0305). Cystatin C at hour 6 was lower than the value measured at hour 24 (p = 0.0142). Similarly, MIOX was lower at hour 6 compared to hour 24 (p = 0.0214). MIOX/creatinine at hour 6 was lower than the value calculated at hour 24 (p = 0.0348). The basal values of MIOX and creatinine were found to have a positive correlation (correlation coefficient r = 0.5946, p = 0.0035).

Conclusions:

Similar to the serum creatinine, the serum MIOX level provides information about kidney functions. RIRS was confirmed to be a safe procedure for the treatment of acute kidney injury with no negative effects on the kidneys.

Frequency of Acute Kidney Injury in tetanus patients of Paedriatic Intensive Care Unit: A Public Hospital Experience

Background and Objective:

Tetanus is a potentially fatal but preventable disease. Mortality is related to severity of the disease, cardiovascular, pulmonary and renal complications. Acute kidney injury (AKI) is a frequent and lethal complication of tetanus. The objective was to determine the frequency of AKI in tetanus patients managed in a public hospital.

Methods:

Children aged 1-12 years admitted in Paediatric Intensive Care Unit (PICU) with the clinical diagnosis of tetanus over three and half years were recruited for the retrospective study. pRIFLE (Pediatric Risk, Injury, Failure, Loss, End) criteria was applied to all cases of tetanus to categorize them as having AKI or not, on the basis of estimated creatinine clearance (ECCL). Comparison was done between AKI and non-AKI cases, as well as between AKI survivors and AKI non-survivors. The study was conducted at PICU of Dr. Ruth K.M. PFau Civil Hospital Karachi for tetanus cases admitted during July 2013 to December 2016

Results:

During the study period, 44 patients of tetanus were enrolled. Nearly 32 % of tetanus patients developed acute renal dysfunction according to PRIFLE criteria. There were overall 15 (34.09%) expiries among tetanus patients among which nine (60%) had AKI. Oliguria was observed in five (35.71%) cases. All the AKI non-survivors had ECCL below 50% and all had autonomic instability. AKI developed towards the end of first week in three cases, mid of second week in four cases and third week in seven cases. Renal replacement therapy (RRT) i.e. peritoneal dialysis (PD) was done in four AKI cases but it did not improve the outcome. CRP was more than 50 in 24 (54.54%) cases. Ventilatory support was given to 85.71% with AKI as compared to 66.66% of non AKI patients.

Conclusion:

Development of AKI in tetanus is multifactorial. Major contributors are severity of the tetanus itself, presence of autonomic instability, ventilator dependency, and sepsis. Presence of AKI worsens the outcome of tetanus in terms of survival, length of stay, hospital cost and ventilator days.

Biomarkers for prediction of renal replacement therapy in acute kidney injury: a systematic review and meta-analysis

Purpose

Acute kidney injury (AKI) frequently occurs in critically ill patients and often precipitates use of renal replacement therapy (RRT). However, the ideal circumstances for whether and when to start RRT remain unclear. We performed evidence synthesis of the available literature to evaluate the value of biomarkers to predict receipt of RRT for AKI.

Methods

We conducted a PRISMA-guided systematic review and meta-analysis including all trials evaluating biomarker performance for prediction of RRT in AKI. A systematic search was applied in MEDLINE, Embase, and CENTRAL databases from inception to September 2017. All studies reporting an area under the curve (AUC) for a biomarker to predict initiation of RRT were included.

Results

Sixty-three studies comprising 15,928 critically ill patients (median per study 122.5 [31–1439]) met eligibility. Forty-one studies evaluating 13 different biomarkers were included. Of these biomarkers, neutrophil gelatinase-associated lipocalin (NGAL) had the largest body of evidence. The pooled AUCs for urine and blood NGAL were 0.720 (95% CI 0.638–0.803) and 0.755 (0.706–0.803), respectively. Blood creatinine and cystatin C had pooled AUCs of 0.764 (0.732–0.796) and 0.768 (0.729–0.807), respectively. For urine biomarkers, interleukin-18, cystatin C, and the product of tissue inhibitor of metalloproteinase-2 and insulin growth factor binding protein-7 showed pooled AUCs of 0.668 (0.606–0.729), 0.722 (0.575–0.868), and 0.857 (0.789–0.925), respectively.

Conclusion

Though several biomarkers showed promise and reasonable prediction of RRT use for critically ill patients with AKI, the strength of evidence currently precludes their routine use to guide decision-making on when to initiate RRT.

Electronic supplementary material

The online version of this article (10.1007/s00134-018-5126-8) contains supplementary material, which is available to authorized users.

The Epidemiology of Cardiac Surgery-Associated Acute Kidney Injury

Purpose

To describe current knowledge on the epidemiology of cardiac surgery-associated acute kidney injury (CSA-AKI) and to formulate recommendations for clinical practice and a research agenda.

Methods

After a modified Delphi analysis by the Acute Dialysis Quality Initiative (ADQI), 4 questions on the epidemiology of CSA-AKI and recommendations for clinical practice and a research agenda were formulated and addressed.

Results

Existing studies on CSA-AKI use over 35 different definitions for CSA-AKI. In addition, there may be important differences in patient characteristics and procedures. This explains the significant variations in reported incidence. Most studies report on CSA-AKI as defined by the need for renal replacement therapy. However, even small decreases in kidney function are associated with a worsened outcome. The workgroup formulated the recommendation to use the AKIN consensus criteria for AKI. One should differentiate early CSA-AKI, caused by the procedure, and late CSA-AKI, associated with the procedure. There may be different clinical scenarios: acute on chronic CSA-AKI, AKI prior to CS, and AKI occurring post CS. Risk factors should be differentiated between pre-, intra-, and post-CS, and between patient-, process-, and procedure-related. Endpoints should include both short-term and long-term outcomes.

Conclusions

Existing data on the epidemiology of CSA-AKI are difficult to compare due to variations in definition and patient cohort. A modified Delphi analysis resulted in a series of recommendations for future research on CSA-AKI.

Fluid and Volume Monitoring

Background

Fluid resuscitation is not only used to prevent acute kidney injury (AKI) but fluid management is also a cornerstone of treatment for patients with established AKI and renal failure. Ultrafiltration removes volume initially from the intravascular compartment inducing a relative degree of hypovolemia. Normal reflex mechanisms attempt to sustain blood pressure constant despite marked changes in blood volume and cardiac output. Thus, compensated shock with a normal blood pressure is a major cause of AKI or exacerbations of AKI during ultrafiltration.

Methods

We undertook a systematic review of the literature using MEDLINE, Google Scholar and PubMed searches. We determined a list of key questions and convened a 2-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated clinical practice recommendations and/or directions for future research.

Results

We defined three aspects of fluid monitoring: i) normal and pathophysiological cardiovascular mechanisms; ii) measures of volume responsiveness and impending cardiovascular collapse during volume removal, and; iii) measured indices of each using non-invasive and minimally invasive continuous and intermittent monitoring techniques. The evidence documents that AKI can occur in the setting of normotensive hypovolemia and that under-resuscitation represents a major cause of both AKI and mortality ion critically ill patients. Traditional measures of intravascular volume and ventricular filling do not predict volume responsiveness whereas dynamic functional hemodynamic markers, such as pulse pressure or stroke volume variation during positive pressure breathing or mean flow changes with passive leg raising are highly predictive of volume responsiveness. Numerous commercially-available devices exist that can acquire these signals.

Conclusions

Prospective clinical trials using functional hemodynamic markers in the diagnosis and management of AKI and volume status during ultrafiltration need to be performed. More traditional measure of preload be abandoned as marked of volume responsiveness though still useful to assess overall volume status.

Serum Cystatin C for Evaluation of Acute Kidney Injury in Adults Treated with Colistin

Objective

Recent studies have shown that serum cystatin C (Cys C) is a better marker for measuring the glomerular filtration rate and may rise more quickly with acute kidney injury (AKI). The purpose of this study was to evaluate the clinical application of serum Cys C to predict colistin-induced nephrotoxicity in comparison with serum creatinine (SCr).

Methods

Thirty-two adult patients with no history of acute or chronic kidney injury having been planned to receive intravenous colistin for an anticipated duration of at least 1 week for any indication were recruited. At baseline and 5 days after colistin treatment, serum Cys C as well as creatinine levels were measured. The incidence of colistin-induced acute renal failure was defined according to the AKIN criteria for SCr. Rise in concentration of Cys C by more than 10% from baseline considered as AKI.

Findings

Colistin-induced nephrotoxicity (defined as SCr ≥0.3 mg/dl) occurred in 6 patients (18.8%). A Cys C increase concentration ≥10% after 5 days of colistin treatment was detected in 15 patients (46.9%). There was a poor agreement between the presence and absence of any SCr-AKI and Cys C-AKI (κ = 0.28, P = 0.04).

Conclusion

Serum Cys C is a better marker of renal function in early stages of AKI and predictive of persistent AKI on colistin treatment.

Myo-inositol Oxygenase as a Novel Marker in the Diagnosis of Acute Kidney Injury

Background

Due to the lack of diagnostic efficiency of serum creatinine in acute kidney injury (AKI), there is a pressing need to develop novel diagnostic markers. Therefore, in this study, we evaluated myo–inositol oxygenase (MIOX), neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C in terms of their applicability in the diagnosis of AKI.

Methods

We enrolled a total of 39 AKI patients and 38 healthy controls in the study. We compared the levels of serum MIOX, NGAL and cystatin C between the two groups.

Results

We found that the concentrations of serum creatinine, blood-urea nitrogen, MIOX and cystatin C were higher in the AKI group. According to the receiver operating characteristic analysis, the area under the curve (AUC) values were 0.694 (95% CI 0.579-0.794) for MIOX and 0.976 (95% CI; 0.912-0.997) for cystatin C. For MIOX, when the cut-off concentration was set to 77.3 pg/mL, the diagnostic sensitivity and specificity were found to be 53.8% (95% CI; 37.2-69.9) and 81.5 (95% CI; 65.7-92.3), respectively. For cystatin C, at the cut-off value of 14 mg/L, the diagnostic sensitivity and specificity were 94.8% (95% CI; 82.7-99.4) and 94.7 % (95% CI 82.3-99.4), respectively.

Conclusion

The measurement of serum MIOX and cystatin C levels is valuable for the diagnosis of AKI. Further research is needed for the evaluation of the potential use of MIOX as a kidney-specific enzyme in the early diagnosis of AKI.

Angiotensinogen as a biomarker of acute kidney injury

Early recognition of acute kidney injury (AKI) is critical to prevent its associated complications as well as its progression to long term adverse outcomes like chronic kidney disease. A growing body of evidence from both laboratory and clinical studies suggests that inflammation is a key factor contributing to the progression of AKI regardless of the initiating event. Biomarkers of inflammation are therefore of interest in the evaluation of AKI pathogenesis and prognosis. There is evidence that the renin angiotensin aldosterone system is activated in AKI, which leads to an increase in angiotensin II (Ang II) formation within the kidney. Ang II activates pro-inflammatory and pro-fibrotic pathways that likely contribute to the progression of AKI. Angiotensinogen is the parent polypeptide from which angiotensin peptides are formed and its stability in urine makes it a more convenient marker of renin angiotensin system activity than direct measurement of Ang II in urine specimens, which would provide more direct information. The potential utility of urinary angiotensinogen as a biomarker of AKI is discussed in light of emerging data showing a strong predictive value of AKI progression, particularly in the setting of decompensated heart failure. The prognostic significance of urinary angiotensinogen as an AKI biomarker strongly suggests a role for renin-angiotensin system activation in modulating the severity of AKI and its outcomes.

Cystatin C Predicts Renal Recovery Earlier Than Creatinine Among Patients With Acute Kidney Injury

Introduction

Serum cystatin C increases earlier than creatinine during acute kidney injury. However, whether cystatin C decreases earlier during recovery is unknown. This retrospective study aimed to determine the temporal trend between creatinine and cystatin C in acute kidney injury.

Methods

We identified hospitalized patients with nonoliguric acute kidney injury who had serial creatinine and cystatin C values measured between May 2015 and May 2016. Demographic and laboratory data, causes of acute kidney injury, and relevant comorbidity data were collected through chart review.

Results

For the 63 identified patients, mean (SD) age was 58.7 (13.9) years; male sex, 62%; white race/ethnicity, 95%. Baseline median (range) creatinine was 1.1 (0.5-3.0) mg/dl; 13% were kidney transplant recipients and 37% received corticosteroids. Comorbidities included malignancy (38%), diabetes mellitus (33%), heart failure (19%), and thyroid disorder (16%). The cause of kidney injury was acute tubular necrosis in 71%, 61% had acute kidney injury stage III, and 33% required dialysis. Cystatin C began to decrease before creatinine in 68% of patients: 1 day earlier, 46%; 2 days earlier, 16%; and 3 days earlier, 6%. In 24% of cases, both began decreasing on the same day; in only 8%, cystatin C decreased after creatinine. Overall, cystatin C mean (95% confidence interval) decrease was 0.92 (0.65-1.18) days before creatinine (P < 0.001).

Conclusion

In summary, cystatin C decreases before creatinine in most hospitalized patients with acute kidney injury. If confirmed in large prospective studies, these findings may have important management implications, possibly shortening hospital stay and reducing costs.

The impact of N-acetylcysteine and ascorbic acid in contrast-induced nephropathy in critical care patients: an open-label randomized controlled study

BACKGROUND

The aim was to investigate whether the use of N-acetylcysteine and ascorbic acid reduce contrast-induced nephropathy incidence in critical care patients.

METHODS

This was a one-center, two-arm, prospective, randomized, open-label, controlled trial in the Intensive Care Unit of the University Hospital of Larissa, Greece. Patients with stable renal function, who underwent non urgent contrast-enhanced computed tomography for diagnostic purposes, were included in the study. Patients in the treatment group (NacA, n = 60) received intravenously N-acetylcysteine (1200 mg) and ascorbic acid (2 g) dissolved separately in 100 ml of normal saline 2 hours before, and at 10 hours and 18 hours following the infusion of contrast agent, while control group patients (CG, n = 64) received only normal saline. All patients received additional hydration. Contrast-induced nephropathy was defined as relative increase by 25% of the baseline values of serum creatinine.

RESULTS

Contrast-induced nephropathy in NacA and CG were 18.33% and 15.6%, respectively (p = 0.81). The percentage change median (interquartile range (IR)) of serum cystatin-C (mg/L) from baseline in patients who underwent contrast-induced tomography, were 37.23% (28.53) and 93.20% (46.90) in NacA and in CG, respectively (p = 0.03). The 8-isoprostane serum levels in NacA were significantly lower compared to CG at 2 hours (p = 0.012) and 24 hours (p = 0.006) following radiocontrast infusion. Multivariate analysis revealed that contrast-induced nephropathy was independently associated with a higher baseline ratio of serum urea/creatinine (odds ratio, 1.02; 95 CI%, 1.00-1.05) and with the use of nephrotoxic medications (odds ratio, 0.24; 95 CI%, 0.06-0.94).

CONCLUSION

Intravenous administration of N-acetylcysteine and ascorbic acid failed to reduce contrast-induced nephropathy in critically ill patients who underwent contrast-enhanced computed tomography, despite a significant reduction of 8-isoprostane levels in treated patients.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01017796 . Registered on 20 November 2009.

NMR spectroscopy and electron microscopy identification of metabolic and ultrastructural changes to the kidney following ischemia-reperfusion injury

Cellular, molecular, and ultrastructural nephron changes associated with ischemia-reperfusion injury-induced acute kidney injury (IRI-AKI) are not completely understood. Here, a multidisciplinary study was used to identify nephron changes in a mouse model of IRI-AKI. Histological analyses indicated distended Bowman's glomerular spaces and proximal and distal tubules. Increased filtrate volume in nephrons was caused by reduced water reabsorption by severely damaged proximal tubule brush borders and blocked flow of filtrate into collecting tubules by mucoprotein casts in distal tubules. Immunohistochemistry revealed protein AKI biomarkers in proximal tubules and glomeruli but not in distal tubules. Nuclear magnetic resonance spectroscopy revealed several metabolites that increased such as valine, alanine, and lactate. Other metabolites such as trigonelline, succinate, 2-oxoisocaproate, and 1- methyl-nicotinamide decreased or were absent in urine following IRI due to altered kidney function or metabolism. Urinary glucose increased due to reduced reabsorption by damaged proximal tubule brush borders. Scanning electron microscopy revealed flattening of podocytes and pedicals surrounding glomerular capillaries, and transmission electron microscopy (TEM) revealed effacement of podocyte pedicals, both consistent with increased hydrostatic pressure in nephrons following IRI-AKI. TEM revealed shortened proximal tubule microvilli in IRI kidneys with diminished lamina propia. TEM showed dramatic loss of mitochondria in distal tubule epithelia of IRI kidneys and emergence of multivesicular bodies of endosomes indicating ongoing cellular death. Collectively, the data define ultrastructural changes to nephrons and altered kidney metabolism associated with IRI-AKI.

Accuracy of neutrophil gelatinase-associated lipocalin for acute kidney injury diagnosis in children: systematic review and meta-analysis

OBJECTIVE

To estimate the accuracy of Neutrophil Gelatinase-Associated Lipocalin (NGAL) as a biomarker for acute kidney injury (AKI) in children.

METHODS

A systematic review of the literature was performed. The review protocol was registered at PROSPERO (CRD 42015024153). We conducted searches in the following databases: Medline (PubMed), LILACS (BVS), SCOPUS (Elsevier), Embase (OVID), Cochrane Central Register of Controlled Trials (CENTRAL), Biomed Central, and ISI Web of Science, from January 1990 to October 2016. For inclusion, studies measured NGAL levels in plasma and urine for AKI in children. For each study, 2 × 2 contingency tables were developed. For statistical analysis we calculated the sensitivity, specificity and diagnostic odds ratio. For methodological assessment, we used Quality Assessment of Diagnostic Accuracy Studies-2. Software used for analysis was Stata 14, and RevMan 5.3.

RESULTS

In total 13 studies were analyzed, which included 1629 children. For urinary NGAL, the pooled sensitivity was 0.76 (95% CI 0.62-0.85) and a pooled specificity 0.93 (95% CI 0.88-0.96). The diagnostic odds ratio (DOR) for the detection of AKI was 43 (95% CI 16-115) and the Area under the curve (AUC) was 0.94 (95% CI 0.92-0.96). For plasma NGAL the combined sensitivity was 0.80 (95% CI 0.64-0.90) and a combined specificity was 0.87 (95% CI 0.74-0.94). The DOR was 26 (95% CI 8.0-82) and AUC was 0.90 (95% CI 0.87-0.94) for the detection of AKI in children.

CONCLUSION

The data suggest that NGAL levels can be an important biomarker for the early detection of AKI in children.

[Acute kidney injury : A clinical syndrome]

Acute kidney injury (AKI) is a clinical syndrome occurring in the context of multiple and diverse disease entities. Although the term AKI implies renal damage as well as functional impairment or a combination of both, diagnosis is solely based on the functional parameters serum creatinine and urine output. Independent of the underlying disease and even assuming full recovery of renal function, AKI is associated with increased morbidity and mortality not only during the acute situation, but also long term. Awareness of the individual risk profile of each patient and the variety of causes and clinical manifestations of AKI is pivotal for prophylaxis, diagnosis, and therapy. The complexity of the clinical syndrome in the context of sepsis, solid organ transplantation, malignancy, and autoimmune diseases requires differentiated diagnostic and therapeutic approaches and interdisciplinary care.

Diagnostic and prognostic value of cystatin C in acute heart failure

BACKGROUND

The accurate early diagnosis of acute kidney injury (AKI) in patients with acute heart failure (AHF) is an unmet clinical need. Cystatin C might improve the early detection of AKI.

METHODS

207 patients presenting to the emergency department with AHF were enrolled. Cystatin C was measured in plasma in a blinded fashion at presentation and serially thereafter. The potential of Cystatin C levels to predict AKI was assessed as the primary endpoint. Long-term mortality was assessed as a secondary endpoint.

RESULTS

At presentation, creatinine (140μmol/L [91-203] vs. 97μmol/L [76-132], p<0.01) and Cystatin C (2.00mg/L [1.30-3.08] vs. 1.45mg/L [1.00-1.90], p<0.01) levels were significantly higher in AKI compared to Non-AKI patients. The diagnostic accuracy for AKI quantified by the area under the receiver operating characteristic curve was mediocre and comparable for both markers (creatinine 0.68; 95%CI 0.58-78 vs. Cystatin C 0.67; 95%CI 0.58-0.76). Serial measurements of Cystatin C did not further increase the prognostic accuracy for AKI. Cystatin C levels were significantly higher in decedents than in survivors (1.90mg/L [1.30-2.70] vs. 1.30mg/L [1.0-1.6], p<0.001). The combination of Cystatin C and BNP levels significantly improved the prediction of mortality provided by either parameter alone. In multivariable regression analysis Cystatin C remained independently associated with mortality (HR 1.41; 95%CI 1.02-1.95).

CONCLUSION

Plasma Cystatin C levels do not adequately predict AKI in patients with AHF. However, in multivariable regression analysis Cystatin C predicted mortality after the adjustment for baseline renal function, AKI, BNP levels and heart failure risk factors.

The effects of prolonged CO2 insufflation on kidney function in a rat pneumoperitoneum model

INTRODUCTION

Pneumoperitoneum (PP) is known to cause ischemia in kidneys and other intra-abdominal organs because of decreased splanchnic blood flow.

AIM

We aimed to determine the degree of renal injury that occurs due to a PP and prolonged PP. We measured renal injury biomarkers and made a histopathological evaluation to estimate the degree of injury and assessed the correlation of biomarkers with histopathological findings.

MATERIAL AND METHODS

Twenty-one female Sprague Dawley rats were separated randomly into three groups. Group 1 was the control group and was given anesthesia for 3 h. In group 2, a PP was administered under anesthesia for 1 h. A pneumoperitoneum was administered under anesthesia to animals in group 3 for 3 h.

RESULTS

Pathological analysis showed a significant statistical difference between the 3 groups. In particular, neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C (Cys C) levels at the 24^th h and preoperative mean urea levels showed a significant difference between the groups. The 24^th-hour NGAL level in group 3 was significantly higher than that of group 1. The preoperative Cys C level was higher in group 1 than in either group 2 or 3. Cys C was decreased significantly in group 1 and increased significantly in both groups 2 and 3.

CONCLUSIONS

The increase in NGAL and Cys C levels directly correlated with the duration of PP and intra-abdominal pressure, and they are therefore good biomarkers in diagnosing acute renal injury in the early phase. Serum creatinine level is not a good biomarker in the early phase of renal injury.

The Incidence, Risk Factors and Outcomes of Postoperative Acute Kidney Injury in Neurosurgical Critically Ill Patients

We investigated the incidence, perioperative risk factors, and outcomes of postoperative acute kidney injury (AKI) in neurosurgical critically ill patients. A prospective multicenter cohort study was conducted, enrolling adult patients who underwent neurosurgical procedure and admitted to the neurosurgical intensive care units (ICU). Postoperative AKI was diagnosed within 7 days after surgery based on the Kidney Disease Improving Global Outcomes criteria. Of 624 enrolled patients, postoperative AKI occurred in 84 patients. AKI was associated with increased rates of ICU and in-hospital mortality, postoperative renal replacement therapy, postoperative tracheotomy, and postoperative tracheal reintubation. Patients who developed AKI had higher total ICU costs, prolonged length of hospital and ICU stay, and longer duration of postoperative mechanical ventilation. Multivariate analysis identified postoperative reoperation (adjusted odds ratio [OR] 5.70 [95% CI, 1.61–20.14]), postoperative concentration of serum cystatin C (adjusted OR 4.53 [95% CI, 1.98–10.39]), use of mannitol during operation (adjusted OR 1.97 [95% CI, 1.13–3.43]), postoperative APACHE II score (adjusted OR 1.11 [95% CI, 1.06–1.16]), and intraoperative estimated blood loss (adjusted OR 1.04 [95% CI, 1.00–1.08]) as independent risk factors for postoperative AKI. Postoperative AKI in neurosurgical critically ill cohort is prevalent and associated with adverse in-hospital outcomes.

Predicting acute kidney injury: current status and future challenges

Acute kidney injury (AKI) is characterized by an acute decline in renal function and is associated to increased mortality rate, hospitalization time, and total health-related costs. The severity of this ‘fearsome’ clinical complication might depend on, or even be worsened by, the late detection of AKI, when the diagnosis is based on the elevation of serum creatinine (SCr). For these reasons, in recent years a great number of new tools, biomarkers and predictive models have been proposed to clinicians in order to improve diagnosis and prevent the development of AKI. The purpose of this narrative paper is to review the current state of the art in prediction and early detection of AKI and outline future challenges.

Personalized Medicine: New Perspectives for the Diagnosis and the Treatment of Renal Diseases

The prevalence of renal diseases is rising and reaching 5-15% of the adult population. Renal damage is associated with disturbances of body homeostasis and the loss of equilibrium between exogenous and endogenous elements including drugs and metabolites. Studies indicate that renal diseases are influenced not only by environmental but also by genetic factors. In some cases the disease is caused by mutation in a single gene and at that time severity depends on the presence of one or two mutated alleles. In other cases, renal disease is associated with the presence of alteration within a gene or genes, but environmental factors are also necessary for the development of disease. Therefore, it seems that the analysis of genetic aspects should be a natural component of clinical and experimental studies. The goal of personalized medicine is to determine the right drug, for the right patient, at the right time. Whole-genome examinations may help to change the approach to the disease and the patient resulting in the creation of "personalized medicine" with new diagnostic and treatment strategies designed on the basis of genetic background of each individual. The identification of high-risk patients in pharmacogenomics analyses will help to avoid many unwarranted side effects while optimizing treatment efficacy for individual patients. Personalized therapies for kidney diseases are still at the preliminary stage mainly due to high costs of such analyses and the complex nature of human genome. This review will focus on several areas of interest: renal disease pathogenesis, diagnosis, treatment, rate of progression and the prediction of prognosis.

Low Versus Standard Urine Output Targets in Patients Undergoing Major Abdominal Surgery: A Randomized Noninferiority Trial

OBJECTIVE

To determine whether a low perioperative minimum urine output target is safe and fluid sparing when compared with the standard target.

BACKGROUND

A minimum hourly urine output of 0.5 mL/kg is a key target guiding perioperative fluid therapy. Few data support this standard practice, which may contribute to perioperative fluid overloading.

METHODS

We randomized patients without significant risk factors for acute kidney injury undergoing elective colectomy to a minimum urine output target of 0.2 mL/kg/h (low group) or 0.5 mL/kg/h (standard group) from induction of anesthesia until 8 AM 2 days after surgery. Maintenance fluids were standardized and additional fluids administered to achieve the targets. Primary outcome was noninferiority for urine neutrophil gelatinase-associated lipocalin on the day after surgery.

RESULTS

Between November 21, 2011 and July 11, 2013, 40 participants completed the study. The low group received 3170 mL (95% confidence interval 2380-3960) intravenous fluids versus 5490 mL (95% confidence interval 4570-6410) in the standard group (P = 0.0004), and was noninferior for neutrophil gelatinase-associated lipocalin [14.7 μg/L (interquartile range 7.60-28.9) vs 18.4 μg/L (interquartile range 8.30-21.2); Pnoninferiority = 0.0011], serum cystatin C (Pnoninferiority < 0.0001), serum creatinine (Pnoninferiority = 0.0004), and measured glomerular filtration (Pnoninferiority = 0.0003). Effective renal plasma flow increased in both groups after surgery, and more in the standard group (Pnoninferiority = 0.125).

CONCLUSIONS

A perioperative urine output target of 0.2 mL/kg/h is noninferior to the standard target of 0.5 mL/kg/h and results in a large intravenous fluid sparing. This target should be adopted in surgical patients without significant kidney injury risk factors.

Use of Biotelemetry to Define Physiology-Based Deterioration Thresholds in a Murine Cecal Ligation and Puncture Model of Sepsis

OBJECTIVES

Murine models of critical illness are commonly used to test new therapeutic interventions. However, these interventions are often administered at fixed time intervals after the insult, perhaps ignoring the inherent variability in magnitude and temporality of the host response. We propose to use wireless biotelemetry monitoring to define and validate criteria for acute deterioration and generate a physiology-based murine cecal ligation and puncture model that is more similar to the conduct of human trials of sepsis.

DESIGN

Laboratory and animal research.

SETTING

University basic science laboratory.

SUBJECTS

Male C57BL/6 mice.

INTERVENTIONS

Mice underwent cecal ligation and puncture, and an HD-X11 wireless telemetry monitor (Data Sciences International) was implanted that enabled continuous, real-time measurement of heart rate, core temperature, and mobility. We performed a population-based analysis to determine threshold criteria that met face validity for acute physiologic deterioration. We assessed construct validity by temporally matching mice that met these acute physiologic deterioration thresholds with mice that had not yet met deterioration threshold. We analyzed matched blood samples for blood gas, inflammatory cytokine concentration, cystatin C, and alanine aminotransferase.

MEASUREMENTS AND MAIN RESULTS

We observed that a 10% reduction in both heart rate and temperature sustained for greater than or equal to 10 minutes defined acute physiologic deterioration. There was significant variability in the time to reach acute deterioration threshold across mice, ranging from 339 to 529 minutes after cecal ligation and puncture. We found adequate construct validity, as mice that met criteria for acute deterioration had significantly worse shock, systemic inflammation (elevated tumor necrosis factor-α, p = 0.003; interleukin-6, p = 0.01; interleukin-10, p = 0.005), and acute kidney injury when compared with mice that had not yet met acute deterioration criteria.

CONCLUSIONS

We defined a murine threshold for acute physiologic deterioration after cecal ligation and puncture that has adequate face and construct validity. This model may enable a more physiology-based model for evaluation of novel therapeutics in critical illness.

Neutrophil gelatinase-associated lipocalin is a better biomarker than cystatin C for the prediction of imminent acute kidney injury in critically ill patients

Aims The prevention of acute kidney injury can be lifesaving for the intensive care unit patients. However, conventional methods are not sufficient for the prediction of the risk of future acute kidney injury. In this study, the promising biomarker, neutrophil gelatinase-associated lipocalin, was compared with cystatin C as an indicator for the risk of future acute kidney injury. Methods One hundred and eighty-three adult patients without chronic kidney disease or renal replacement therapy were included in this study. The plasma and urine concentrations of neutrophil gelatinase-associated lipocalin and cystatin C were assessed on the second day after intensive care unit admission and were followed for seven days to monitor the development of acute kidney injury. Acute kidney injury diagnosis was based on the risk, injury, failure, loss, end-stage renal failure criteria. Results Thirty-four per cent of the patients had acute kidney injury; 17 patients who did not fulfil criteria at the beginning, developed acute kidney injury from days 3 to 7 after admission. The mean serum creatinine on admission did not significantly differ between this and control groups (0.72 ± 0.20 and 0.83 ± 0.21; P = 0.060); however, the serum and urinary neutrophil gelatinase-associated lipocalin concentrations on the second day were significantly different (median: 75.69 [54.18-91.18] and 123.68 [90.89-166.31], P = 0.001; and median: 17.60 [8.56-34.04] and 61.37 [24.59-96.63], P = 0.001). Notably, the 48-h serum cystatin C concentration did not differ. Conclusion Neutrophil gelatinase-associated lipocalin concentrations in the urine and serum on the second day of intensive care unit admission could be used to predict the development of acute kidney injury in the following three to seven days in the intensive care unit; however, the cystatin C concentration did not have predictive value.

Value of Serum Cystatin C Measurement in the Diagnosis of Sepsis-Induced Kidney Injury and Prediction of Renal Function Recovery

PURPOSE

Acute kidney injury (AKI) is common in critically ill patients. Serum cystatin C has emerged as a reliable marker of AKI. We sought to assess the value of serum cystatin C for early detection and prediction of renal function recovery in patients with sepsis.

MATERIALS AND METHODS

Sepsis patients (113 AKI patients and 49 non-AKI patients) admitted to the intensive care unit (ICU) were included. Serum creatinine and cystatin C levels and glomerular filtration rate were measured on days 0, 1, 3, and 7.

RESULTS

Serum cystatin C levels were significantly higher in AKI patients than in non-AKI patients at all time points. Multivariate analysis showed that only serum cystatin C levels on day 0 were associated with AKI development [odds ratio (OR)=19.30; 95% confidence interval (CI)= 2.58-144.50, p<0.001]. Linear mixed model analysis showed significant variation in cystatin C levels between the recovery and non-recovery groups over time (p=0.001). High levels of serum cystatin C at day 0 (OR=1.64; 95% CI=1.00-2.68, p=0.048) were associated with recovery of AKI.

CONCLUSION

Serum cystatin C level was found to be associated with the development and worsening of AKI in ICU patients with sepsis.

Comparison of Effects of Low-Flow Sevoflurane and Low-Flow Desflurane Anaesthesia on Renal Functions Using Cystatin C

OBJECTIVE

Numerous studies have indicated nephrotoxic effects of sevoflurane because of its two bioproducts compound A and fluoride. Cystatin C (CyC) is a more sensitive biomarker than creatinine to show early and mild changes in kidney function. We designed this prospective randomised study to compare the effects of low-flow sevoflurane anaesthesia and low-flow desflurane anaesthesia on renal functions based on CyC levels. No studies have evaluated the effects of low-flow sevoflurane anaesthesia on renal functions based on CyC levels to date.

METHODS

Thirty American Society of Anesthesiologists (ASA) physical status I-II patients who were scheduled for urological procedures were enrolled in this study. The patients were randomly assigned to 2 groups: low-flow sevoflurane anaesthesia or low-flow desflurane anaesthesia. Serum urea, creatinine and CyC levels were measured before the operation, just before extubation and 24 h after the operation. Creatinine clearance was calculated in the first 24-h urine sample.

RESULTS

There were no significant differences in serum urea, creatinine and CyC levels or 24 h creatinine clearance between the groups.

CONCLUSION

Our study demonstrates with a more sensitive biomarker, CyC, that low-flow sevoflurane anaesthesia is safe in terms of the effects on renal function.

Performance of urinary kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, and N-acetyl-β-D-glucosaminidase to predict chronic kidney disease progression and adverse outcomes

Urinary biomarkers can predict the progression of chronic kidney disease (CKD). In this study, kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and N-acetyl-β-D-glucosaminidase (NAG) were correlated with the stages of CKD, and the association of these biomarkers with CKD progression and adverse outcomes was determined. A total of 250 patients, including 111 on hemodialysis, were studied. Urinary KIM-1, NGAL, and NAG were measured at baseline. Patients not on dialysis at baseline who progressed to a worse CKD stage were compared with those who did not progress. The association of each biomarker and selected covariates with progression to more advanced stages of CKD, end-stage kidney disease, or death was evaluated by Poisson regression. NGAL was moderately correlated (r^s=0.467, P<0.001) with the five stages of CKD; KIM-1 and NAG were also correlated, but weakly. Sixty-four patients (46%) progressed to a more advanced stage of CKD. Compared to non-progressors, those patients exhibited a trend to higher levels of KIM-1 (P=0.064) and NGAL (P=0.065). In patients not on dialysis at baseline, NGAL was independently associated with progression of CKD, ESKD, or death (RR=1.022 for 300 ng/mL intervals; CI=1.007-1.037, P=0.004). In patients on dialysis, for each 300-ng/mL increase in urinary NGAL, there was a 1.3% increase in the risk of death (P=0.039). In conclusion, urinary NGAL was associated with adverse renal outcomes and increased risk of death in this cohort. If baseline urinary KIM-1 and NGAL predict progression to worse stages of CKD is something yet to be explored.

Evaluation of clinically available renal biomarkers in critically ill adults: a prospective multicenter observational study

BACKGROUND

Although serum cystatin C (sCysC), urinary N-acetyl-β-D-glucosaminidase (uNAG), and urinary albumin/creatinine ratio (uACR) are clinically available, their optimal combination for acute kidney injury (AKI) detection and prognosis prediction remains unclear. We aimed to assess the discriminative abilities of these biomarkers and their possible combinations for AKI detection and intensive care unit (ICU) mortality prediction in critically ill adults.

METHODS

A multicenter, prospective observational study was conducted in mixed medical-surgical ICUs at three tertiary care hospitals. One thousand eighty-four adult critically ill patients admitted to the ICUs were studied. We assessed the use of individual biomarkers (sCysC, uNAG, and uACR) measured at ICU admission and their combinations with regard to AKI detection and prognosis prediction.

RESULTS

AUC-ROCs for sCysC, uNAG, and uACR were calculated for total AKI (0.738, 0.650, and 0.683, respectively), severe AKI (0.839, 0.706, and 0.771, respectively), and ICU mortality (0.727, 0.793, and 0.777, respectively). The panel of sCysC plus uNAG detected total and severe AKI with significantly higher accuracy than either individual biomarkers or the other two panels (uNAG plus uACR or sCysC plus uACR). For detecting total AKI, severe AKI, and ICU mortality at ICU admission, this panel yielded AUC-ROCs of 0.756, 0.863, and 0.811, respectively; positive predictive values of 0.71, 0.31, and 0.17, respectively; and negative predictive values of 0.81, 0.97, and 0.98, respectively. Moreover, this panel significantly contributed to the accuracy of the clinical models for AKI detection and ICU mortality prediction, as measured by the AUC-ROC, continuous net reclassification index, and incremental discrimination improvement index. The comparable performance of this panel was further confirmed with bootstrap internal validation.

CONCLUSIONS

The combination of a functional marker (sCysC) and a tubular damage marker (uNAG) revealed significantly superior discriminative performance for AKI detection and yielded additional prognostic information on ICU mortality.

The discrepancy between serum creatinine and cystatin C can predict renal function after treatment for postrenal acute kidney injury: multicenter study and pooled data analysis

BACKGROUND

Although serum cystatin C and creatinine are used as practical markers of renal function, the discrepancy between them in postrenal acute kidney injury (AKI) cases was reported. The aim of this study was to determine whether the preoperative serum cystatin C (pre-CysC) level could predict clinical outcomes after treatment in patients with postrenal AKI.

METHODS

Patients who underwent urological interventions with postrenal AKI were enrolled in this prospective observational study. Associations among preoperative serum creatinine (pre-sCr), pre-CysC, and nadir postoperative serum creatinine (post-sCr) were evaluated. In addition, based on our results in combination with detailed data from the literature, a predictive equation for postoperative serum creatinine (post-sCr) was developed by simple regression analysis and validated using Bland-Altman plots.

RESULTS

Finally, 19 patients were eligible for analysis in this study. The value calculated by subtracting pre-CysC (mg/L) from pre-sCr (mg/dl) had a strong correlation to the decrement of serum creatinine (r = 0.9508, p < 0.0001). We added the data of 16 patients obtained from the literature to our series, which were totally randomized into 2 groups, training set and validation set in a 2:1 ratio (n = 23 and 12, respectively) to develop and validate a predictive equation for post-sCr. The mean difference between the predictive and actual post-sCr, -0.68 mg/dl (95% CI -1.62 to 0.26) in the validation set was within the limits of agreement.

CONCLUSION

We showed that the discrepancy between pre-sCr and pre-CysC could predict improvement of renal function after intervention in patients with postrenal AKI.

Predictive value of serum cystatin C for acute kidney injury in adults: a meta-analysis of prospective cohort trials

The role of serum cystatin C (Scys) for the detection of acute kidney injury (AKI) has not been fully discussed. This meta-analysis was aimed to investigate the overall diagnostic accuracy of Scys for AKI in adults, and further identify factors affecting its performance. Studies before Sept. 2016 were retrieved from PubMed, Embase, Web of Science and the Cochrane Library. A total of 30 prospective cohort studies (involving 4247 adults from 15 countries, 982 patients occurring AKI) were included. The revised Quality Assessment for Studies of Diagnostic Accuracy (QUADAS-2) tools demonstrated no significant bias had influenced the methodological quality of the included studies. Scys showed a high predictive power for all-cause AKI, that the area under the receiver operating characteristic curve was 0.89. The detailed assessment parameters, such as sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio for Scys were 0.82, 0.82, 4.6, 0.22 and 21, respectively. Although Scys could be slightly influenced by the following factors: settings, AKI diagnostic criteria, ethnicity, determination method, age and gender, these factors above did not reach statistically significance. In conclusion, Scys could be a vital promising marker to screen out AKI.

Amelioration of high fat diet-induced nephropathy by cilostazol and rosuvastatin

Multiple comorbidities of metabolic disorders are associated with facilitated chronic kidney disease progression. Anti-platelet cilostazol is used for the treatment of peripheral artery disease. In this study, we investigated the potential beneficial effects of cilostazol and rosuvastatin on metabolic disorder-induced renal dysfunctions. C57BL/6 mice that received high fat diet (HFD) for 22 weeks and a low dose of streptozotocin (STZ, 40 mg/kg) developed albuminuria and had increased urinary cystatin C excretion, and cilostazol treatment (13 weeks) improved these markers. Histopathological changes, including glomerular mesangial expansion, tubular vacuolization, apoptosis, and lipid accumulation were ameliorated by cilostazol treatment. Tubulointerstitial fibrosis that was indicated by the increases in collagen and transforming growth factor-β1 subsided by cilostazol. Renoprotective effects were also observed in rosuvastatin-treated mice, and combinatorial treatment with cilostazol and rosuvastatin demonstrated enhanced ameliorative effects in histopathological evaluations. Notably, repressed renal heme oxygenase-1 (Ho-1) level in HFD/STZ mice was restored in cilostazol group. Further, we demonstrated that cilostazol enhanced Nrf2/Ho-1 signaling in cultured proximal tubular epithelial cells. Collectively, these results suggest the potential advantageous use of cilostazol as an adjunctive therapy with statins for the amelioration of metabolic disorder-associated renal injury.

Serum cystatin C for acute kidney injury evaluation in children treated with aminoglycosides

BACKGROUND

Serum cystatin C (CysC) is a more accurate glomerular filtration rate marker than serum creatinine (SCr) and may rise more quickly with acute kidney injury (AKI).

METHODS

We performed a prospective cohort study of 81 non-critically ill children during 110 aminoglycoside (AG) treatments. We calculated area under the curve (AUC) for CysC to diagnose SCr-defined AKI and predict persistent AKI. SCr-AKI definition was based on the Kidney Disease: Improving Global Outcomes (≥stage 1: ≥50 % or 26.5 μmol/l SCr rise from baseline; stage 2: SCr doubling); CysC-AKI was based on a modified version using CysC rise.

RESULTS

SCr-AKI and CysC-AKI developed in 45 and 48 % treatments, respectively. CysC rise predicted stage 1 (AUC = 0.75, 95 % CI 0.60-0.90) and 2 (AUC = 0.85, 95 % CI 0.75-0.95) SCr-AKI 2 days before SCr-AKI attainment. The best combined sensitivity/specificity for percent CysC rise to predict stage 1 SCr-AKI was with a 44 % CysC rise (sensitivity = 65 %, specificity = 83 %). CysC rise on day of SCr-AKI development was associated with SCr-AKI ≥48 h (AUC = 0.73, 95 % CI 0.56-0.90) and ≥50 % persistent SCr rise at treatment end (AUC = 0.76, 95 % CI 0.61-0.90).

CONCLUSIONS

CysC is as an early AKI biomarker and predictive of persistent AKI on aminoglycoside treatment.

Diagnostic accuracy of serum cystatin C for early recognition of contrast induced nephropathy in Western Indians undergoing cardiac catheterization

Aims

We aimed to compare the diagnostic efficacy of serum cystatin C (sCyC) for contrast induced nephropathy (CIN) in Western Indians undergoing cardiac catheterization. We also aimed to propose a clinically applicable cut-off of sCyC for early identification of CIN in this ethnic group.

Methods

In this prospective study, 253 patients undergoing coronary angiography and/or percutaneous coronary intervention were enrolled. The demographic and risk factor details, levels of sCr at baseline, 24 and 48 h after the procedure, whereas baseline and 24 h levels of sCyC were noted. Increase of 0.5 mg/dl or ≥25% from baseline sCr was used to define CIN. Optimum cut off of sCyC for CIN diagnosis was obtained using Receiver Operating Characteristic (ROC) curve analysis.

Results

After 48 h of contrast media (CM) exposure, the incidence of CIN was 12.25% (31 patients) according to sCr definition, where only 3.9% (10 patients) had sCr rise in 24 h. Overall significant (p < 0.0001) rise in mean levels of sCr (48 h) and sCyC (24 h) was observed in CIN patients. However, the mean sCr rise at 24 h was non-significant. The optimum cut off of sCyC for diagnosing CIN was found to be a rise of ≥10% from baseline (AUC – 0.901; sensitivity – 100%, specificity – 77.89%). According to sCyC, 94 (37.15%) patients had CIN.

Conclusion

We may conclude that a rise of ≥10% in sCyC at 24 h could be used as a reliable marker for identification of CIN in western Indians undergoing cardiac catheterization.

Standard dosing of piperacillin and meropenem fail to achieve adequate plasma concentrations in ICU patients

BACKGROUND

Controversies remain regarding optimal dosing and the need for plasma concentration measurements when treating intensive care patients with beta-lactam antibiotics.

METHODS

We studied ICU patients treated with either antibiotic, excluding patients on renal replacement therapy. Antibiotic concentrations were measured at the mid and end of the dosing interval, and repeated after 2-3 days when feasible. Glomerular filtration rate (GFR) was estimated from plasma creatinine and cystatin C, GFR calculated from cystatin C (eGFR) and measured creatinine clearance (CrCl). Measured concentrations were compared to the clinical susceptible breakpoints for Pseudomonas aeruginosa, 16 and 2 mg/l for piperacillin and meropenem respectively.

RESULTS

We analysed 33 and 31 paired samples from 20 and 19 patients treated with piperacillin-tazobactam and meropenem respectively. Antibiotic concentrations at the mid and end of the dosing interval were for piperacillin, 27.0 (14.7-52.9) and 8.6 (2.7-30.3); and for meropenem, 7.5 (4.7-10.2) and 2.4 (1.0-3.5). All values median (interquartile range) and concentrations in mg/l. The percentage of measured concentrations below the breakpoint at the mid and end of the dosing interval were for piperacillin, 27% and 61%; and for meropenem, 6% and 48%. Lower estimates of GFR were associated with higher concentrations but concentrations varied greatly between patients with similar GFR. The correlation with terminal concentration half-life was similar for eGFR and CrCl.

CONCLUSIONS

With standard doses of meropenem and piperacillin-tazobactam, plasma concentrations in ICU patients vary > 10-fold and are suboptimal in a significant percentage of patients. The variation is large also between patients with similar renal function.

Predictive performance of glomerular filtration rate estimation equations based on cystatin C versus serum creatinine values in critically ill patients

PURPOSE

The predictive performance of glomerular filtration rate (GFR) estimation equations based on cystatin C versus serum creatinine (SCr) values in critically ill patients was evaluated.

METHODS

A retrospective observational study was performed in the medical intensive care unit (ICU) of a university hospital from October 2006 through September 2007. All consecutively admitted critically ill patients older than 18 years who stayed in the ICU for more than 48 hours with a urinary bladder catheter in place were included in the study. Data collected included SCr, cystatin C, serum albumin, blood urea nitrogen, and 24-hour urine creatinine clearance [Formula: see text] levels. The following equations were also used to determine the estimated GFR that was compared with the reference [Formula: see text] for all patients in the study: Arnal-Dade using cystatin C, Cockcroft-Gault using actual body weight, Cockcroft-Gault using ideal body weight, Jelliffe, Modification of Diet in Renal Disease (MDRD), and four-variable version MDRD (MDRD-4).

RESULTS

This study included 241 measurements corresponding to 131 critically ill patients. The cystatin C-based equation underestimated [Formula: see text], whereas overestimation by every SCr-based formula was observed in the whole cohort and in the [Formula: see text] subgroup; MDRD-4 was the most biased equation in every analysis. There were no significant differences in precision, except for great variability in the subgroup with a [Formula: see text] of <60 mL/min/1.73 m(2), where the MDRD equation showed better results than the cystatin C-based equation (33.5% versus 38.9%). No equations fulfilled concordance requirements with [Formula: see text].

CONCLUSION

A retrospective observational study showed no evidence of superiority of a cystatin C-based equation over SCr-based equations to estimate the GFR in an ICU population.

Erythrocyte superoxide dismutase as a biomarker of septic acute kidney injury

Background

Oxidative stress is a key feature of sepsis and could be a common pathophysiological pathway between septic shock and acute kidney injury (AKI) Our objective was to evaluate the erythrocyte superoxide dismutase (SOD1) activity as predictor of AKI in patients with septic shock.

Methods

This is a prospective observational study that evaluated 175 consecutive patients over the age of 18 years with septic shock upon intensive care unit (ICU) admission. However, 43 patients were excluded (27 due to AKI at ICU admission). Thus, 132 patients were enrolled in the study. At the time of the patients’ enrollment, demographic information was recorded. Blood samples were taken within the first 24 h of the patient’s admission to determine the erythrocyte SOD1 activity. All patients were followed throughout the ICU stay, and the development of AKI was evaluated. In addition, we also evaluated 17 control subjects.

Results

The mean age of patients with septic shock was 63.2 ± 15.7 years, 53 % were male and the median ICU stay was 8 days (4–16). Approximately 50.7 % developed AKI during the ICU stay. The median erythrocyte SOD1 activity was 2.92 (2.19–3.92) U/mg Hb. When compared to control subjects, septic shock patients had a higher serum malondialdehyde concentration and lower erythrocyte SOD1 activity. In univariate analysis, erythrocyte SOD1 activity was lower in patients who developed AKI. The ROC curve analysis revealed that lower erythrocyte SOD1 activity was associated with AKI development (AUC 0.686; CI 95 % 0.595–0.777; p < 0.001) at the cutoff of <3.32 U/mg Hb. In the logistic regression models, SOD1 activity higher than 3.32 U/mg Hb was associated with protection of AKI development when adjusted by hemoglobin, phosphorus and APACHE II score (OR 0.309; CI 95 % 0.137–0.695; p = 0.005) and when adjusted by age, gender, chronic kidney disease, admission category (medical or surgery) and APACHE II score (OR 0.129; CI 95 % 0.033–0.508; p = 0.003).

Conclusions

In conclusion, our data suggest that erythrocyte SOD1 activity could play a role as an early marker of septic AKI and could be seen as a new research avenue in the field of biomarker in AKI. However, our study did not show a strong correlation between SOD activity and AKI. Nevertheless, these original data do warrant further research in order to confirm or not this hypothesis.

Kidney biomarkers in cirrhosis

Impaired renal function due to acute kidney injury (AKI) and/or chronic kidney diseases (CKD) is frequent in cirrhosis. Recurrent episodes of AKI may occur in end-stage cirrhosis. Differential diagnosis between functional (prerenal and hepatorenal syndrome) and acute tubular necrosis (ATN) is crucial. The concept that AKI and CKD represent a continuum rather than distinct entities, is now emerging. Not all patients with AKI have a potential for full recovery. Precise evaluation of kidney function and identification of kidney changes in patients with cirrhosis is central in predicting reversibility. This review examines current biomarkers for assessing renal function and identifying the cause and mechanisms of impaired renal function. When CKD is suspected, clearance of exogenous markers is the reference to assess glomerular filtration rate, as creatinine is inaccurate and cystatin C needs further evaluation. Recent biomarkers may help differentiate ATN from hepatorenal syndrome. Neutrophil gelatinase-associated lipocalin has been the most extensively studied biomarker yet, however, there are no clear-cut values that differentiate each of these conditions. Studies comparing ATN and hepatorenal syndrome in cirrhosis, do not include a gold standard. Combinations of innovative biomarkers are attractive to identify patients justifying simultaneous liver and kidney transplantation. Accurate biomarkers of underlying CKD are lacking and kidney biopsy is often contraindicated in this population. Urinary microRNAs are attractive although not definitely validated. Efforts should be made to develop biomarkers of kidney fibrosis, a common and irreversible feature of CKD, whatever the cause. Biomarkers of maladaptative repair leading to irreversible changes and CKD after AKI are also promising.

The potential use of biomarkers in predicting contrast-induced acute kidney injury

Contrast-induced acute kidney injury (CI-AKI) is a problem associated with the use of iodinated contrast media, causing kidney dysfunction in patients with preexisting renal failure. It accounts for 12% of all hospital-acquired kidney failure and increases the length of hospitalization, a situation that is worsening with increasing numbers of patients with comorbidities, including those requiring cardiovascular interventional procedures. So far, its diagnosis has relied upon the rise in creatinine levels, which is a late marker of kidney damage and is believed to be inadequate. Therefore, there is an urgent need for biomarkers that can detect CI-AKI sooner and more reliably. In recent years, many new biomarkers have been characterized for AKI, and these are discussed particularly with their use in known CI-AKI models and studies and include neutrophil gelatinase-associated lipocalin, cystatin C (Cys-C), kidney injury molecule-1, interleukin-18, N-acetyl-β-d-glucosaminidase, and L-type fatty acid-binding protein (L-FABP). The potential of miRNA and metabolomic technology is also mentioned. Early detection of CI-AKI may lead to early intervention and therefore improve patient outcome, and in future any one or a combination of several of these markers together with development in technology for their analysis may prove effective in this respect.

Urinary C-type natriuretic peptide excretion: a promising biomarker to detect underlying renal injury and remodeling both acutely and chronically

Acute kidney injury (AKI) refers to a sudden decline in renal function. A growing body of evidence demonstrates that AKI is a risk factor for the future development or accelerated progression of chronic kidney disease (CKD), whereas the actual distinction between AKI and CKD remains unknown. CNP is predominantly present in the kidney and possesses multiple renoprotective properties. Urinary CNP excretion tends to be high in AKI, whereas back to the baseline in CKD. The dynamic changes in urinary CNP excretion may help detect underlying renal injury and remodeling both acutely and chronically.

Efficacy of urinary midkine as a biomarker in patients with acute kidney injury

BACKGROUND

The mortality and morbidity associated with acute kidney injury (AKI) remains high, despite advances in interventions. A multifunctional heparin-binding growth factor, midkine (MK), is involved in the pathogenesis of ischemic kidney injury. However, the clinical relevance of MK has not yet been elucidated. The present study investigated whether urinary MK can serve as a novel biomarker of AKI.

METHODS

We initially compared the predictive value of MK with other urinary biomarkers, including N-acetyl-β-D-glucosaminidase (NAG), interleukin (IL)-18, and neutrophil gelatinase-associated lipocalin (NGAL), for the detection and differential diagnosis of established AKI (549 patients). Subsequently, the reliability of MK for the early detection of AKI was prospectively evaluated in 40 patients undergoing elective abdominal aortic aneurysm surgery. Urine samples were obtained at baseline, the period of aortic cross-clamping and declamping, the end of the surgery, and on post-operative day 1.

RESULTS

The areas under the receiver operating characteristic curves for the diagnosis of AKI in various kidney diseases were 0.88, 0.70, 0.72, and 0.84 for MK, NAG, IL-18, and NGAL, respectively. When the optimal cutoff value of urinary MK was set at 11.5 pg/mL, the sensitivity and specificity were 0.87 and 0.85, respectively. In the second study, urinary MK peaked at the period of aortic declamping, about 1 h after cross-clamping in patients with AKI. Interestingly, the rise of MK in AKI patients was very precipitous compared with other biomarker candidates.

CONCLUSION

Urinary MK was prominent in its ability to detect AKI and may allow the start of preemptive medication.

A mixed grape and blueberry extract is safe for dogs to consume

Background

Grape and blueberry extracts are known to protect against age-related cognitive decline. However, beneficial effects achieved by mixing grape and blueberry extracts have yet to be evaluated in dogs, or their bioavailability assessed. Of concern to us were cases of acute renal failure in dogs, after their ingestion of grapes or raisins. The European Pet Food Industry Federation (2013) considers only the grape or raisin itself to be potentially dangerous; grape-seed extracts per-se, are not considered to be a threat. Our aim was therefore to evaluate the renal and hepatic safety, and measure plasma derivatives of a polyphenol-rich extract from grape and blueberry (PEGB; from the Neurophenols Consortium) in dogs. Polyphenol expression was analyzed by UHPLC-MS/MS over 8 hours, for dogs given PEGB at 4 mg/kg. Safety was evaluated using four groups of 6 dogs. These groups received capsules containing no PEGB (control), or PEGB at 4, 20, or 40 mg/kg BW/d, for 24 weeks. Blood and urine samples were taken the week prior to study commencement, then at the end of the 24-wk study period. Routine markers of renal and liver damage, including creatinine (Creat), blood urea nitrogen, albumin, minerals, alkaline phosphatase (ALP), and alanine transaminase (ALT) were measured. Biomarkers for early renal damage were also evaluated in plasma (cystatin C (CysC), and neutrophil gelatinase-associated lipocalin (NGAL)), and urine (CysC, clusterin (Clu), and NGAL). Ratios of urinary biomarkers to Creat were calculated, and compared with acceptable maximal values obtained for healthy dogs, as reported in the literature.

Results

While several PEGB-specific polyphenols and metabolites were detected in dog plasma, at the end of the PEGB consumption period, our biomarker analyses presented no evidence of either renal or liver damage (Creat, BUN, ionogram, albumin and ALT, ALP). Similarly, no indication of early renal damage could be detected. Plasma CysC, urinary CysC/Creat, Clu/Creat, and NGAL/Creat ratios were all beneath reported benchmarked maximums, with no evidence of PEGB toxicity.

Conclusions

Long-term consumption of a pet specific blend of a polyphenol-rich extract from grape and blueberry (PEGB; from the Neurophenols Consortium), was not associated with renal or hepatic injury, and can therefore be considered safe.

Cystatin C and NGAL as Biomarkers for Early Detection of Acute Kidney Injury in Geriatrics

Acute kidney injury (AKI) is associated with cardiovascular mortality and morbidity especially in high-risk patients undergoing cardiac surgery. It ranges from 7.7% to 28.1% in different studies. The aim of this study was to compare cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) with Creatinine as an early marker for acute kidney injury in geriatrics. From 2013 through 2015, 307 consecutive high-risk elderly patients older than 70 years undergoing emergency coronary artery bypass grafting using extracorporeal circulation were studied. All patients underwent diagnostic coronary angiography and the surgical procedure within 1 week in single hospital stay and were randomized according to timing of interval between coronary angiographyand cardiac procedure as follows: group I, less than 2 days; group II, between 2 and 4 days; and group III, higher than 4 days. Renal function was analyzed by serum cystatin C, NGAL, and creatinine. Blood samples were obtained from each patient at five time points: basal value before operation, in the four hours after operation, and on the first, third, and fifth postoperative days. Glomerular filtration rate (GFR) was calculated by Cockcroft-Gault (CG). A total of 56 patients developed postoperative acute kidney failure according to the risk, injury, and failure; and loss; and end-stage kidney disease classification. Perioperative fluid requirements, urine output, and vasopressor need during and after cardiopulmonary bypass were similar. 30-day mortality in groups was higher in group I than group II and group III (P = 0.025). AKI was least prominent in group III compared to group I and group II (P = 0.001) and expectedly, postoperative dialysis requirement was least common in group III (15, 16.66%). Patients in group III had the most favorable clinical outcome with regards to the length of ICU and hospital stay. Overall serum creatinine, cystatin C, and urine NGAL levels changed significantly throughout the entire length of following-up period in group I and group II, but not in group III. Changes in serum levels of cystatin, creatinine, and creatinine clearance were prominent in later than 24 hours. Urinary NGAL was the first variable to rise in the immediate postoperative period. Cystatin GFR was a more rapid marker than serum creatinine GFR to show acute kidney injury in three groups was a significant marker.

TIMP2•IGFBP7 biomarker panel accurately predicts acute kidney injury in high-risk surgical patients

Supplemental digital content is available in the text.

BACKGROUND

Acute kidney injury (AKI) is an important complication in surgical patients. Existing biomarkers and clinical prediction models underestimate the risk for developing AKI. We recently reported data from two trials of 728 and 408 critically ill adult patients in whom urinary TIMP2•IGFBP7 (NephroCheck, Astute Medical) was used to identify patients at risk of developing AKI. Here we report a preplanned analysis of surgical patients from both trials to assess whether urinary tissue inhibitor of metalloproteinase 2 (TIMP-2) and insulin-like growth factor–binding protein 7 (IGFBP7) accurately identify surgical patients at risk of developing AKI.

STUDY DESIGN

We enrolled adult surgical patients at risk for AKI who were admitted to one of 39 intensive care units across Europe and North America. The primary end point was moderate-severe AKI (equivalent to KDIGO [Kidney Disease Improving Global Outcomes] stages 2–3) within 12 hours of enrollment. Biomarker performance was assessed using the area under the receiver operating characteristic curve, integrated discrimination improvement, and category-free net reclassification improvement.

RESULTS

A total of 375 patients were included in the final analysis of whom 35 (9%) developed moderate-severe AKI within 12 hours. The area under the receiver operating characteristic curve for [TIMP-2]•[IGFBP7] alone was 0.84 (95% confidence interval, 0.76–0.90; p < 0.0001). Biomarker performance was robust in sensitivity analysis across predefined subgroups (urgency and type of surgery).

CONCLUSION

For postoperative surgical intensive care unit patients, a single urinary TIMP2•IGFBP7 test accurately identified patients at risk for developing AKI within the ensuing 12 hours and its inclusion in clinical risk prediction models significantly enhances their performance.

LEVEL OF EVIDENCE

Prognostic study, level I.

Analysis of urine biomarkers for early determination of acute kidney injury in non-septic and non-asphyxiated critically ill preterm neonates

OBJECTIVE

We designed the present study to test the hypothesis that urinary biomarkers might predict acute kidney injury (AKI) development in non-septic and non-asphyxiated critically ill preterm infants. We evaluated urine (u) sistatin-C (uCys-C), kidney injury molecule-1 (uKIM-1) and neutrophil gelatinase associate lipocaline (uNGAL) as markers of AKI.

METHODS

Sixty-four preterm infants with gestational age between 28 and 32 weeks were included in this study. Biomarkers were measured on day of life (DOL) 1, 3, and 7.

RESULTS

uNGAL levels in the AKI group were significantly higher than in no-AKI group on DOL 1, 3 and 7 (p = 0.016, p = 0.007 and p = 0.0014, respectively).

CONCLUSIONS

uNGAL is sensitive, early, and noninvasive AKI biomarkers, increasing significantly in non-septic and non-asphyxiated critically ill preterm neonates.