Reactive oxygen species and the pathogenesis of radiocontrast-induced nephropathy. Invest Radiol. 2010;45:188-195. [PMID: 20195159 DOI: 10.1097/rli.0b013e3181d2eed8]

Effect of statins on post-contrast acute kidney injury: a multicenter retrospective observational study

BACKGROUND

Post-contrast acute kidney injury (PC-AKI) is a severe complication of coronary angiography (CAG) and percutaneous coronary intervention (PCI). Currently, the effect of statins on PC-AKI and its mechanism remains unclear.

METHODS

This multicenter retrospective observational study included 4386 patients who underwent CAG or PCI from December 2006 to December 2019 in Sir Run Run Shaw Hospital and its medical consortium hospitals. Serum creatinine pre- or post-procedure within 72 h after PCI was recorded. Multivariate logical regression was used to explore whether preoperative use of statins was protective from PC-AKI. The path analysis model was then utilized to look for the mediation factors of statins.

RESULTS

Four thousand three hundred eighty-six patients were enrolled totally. The median age of the study population was 68 years old, 17.9% with PC-AKI, and 83.3% on preoperative statins therapy. The incidence of PC-AKI was significantly lower in group of patients on statins therapy. Multivariate regression indicated that preoperative statins therapy was significantly associated with lower percentage of elevated creatinine (β: -0.118, P < 0.001) and less PC-AKI (OR: 0.575, P < 0.001). In the preoperative statins therapy group, no statistically significant difference was detected between the atorvastatin and rosuvastatin groups (OR: 1.052, P = 0.558). Pathway model analysis indicated a direct protective effect of preoperative statins therapy on PC-AKI (P < 0.001), but not through its lipid-lowering effect (P = 0.277) nor anti-inflammatory effect (P = 0.596). Furthermore, it was found that "low-density lipoprotein cholesterol (LDL-C)→C-reactive protein (CRP)" mediated the relationship between preoperative statins therapy and PC-AKI (P = 0.007). However, this only explained less than 1% of the preoperative protective effects of statins on PC-AKI.

CONCLUSION

Preoperative statins therapy is an independent protective factor of PC-AKI, regardless of its type. This protective effect is not achieved by lipid-lowering effect or anti-inflammatory effect. These findings underscore the potential use of statins in preventing PC-AKI among those at risk.

Comprehensive analysis of the long non-coding RNA expression profile and functional roles in a contrast-induced acute kidney injury rat model

Long non-coding RNAs (lncRNAs) have been identified as a class of regulatory RNAs that participate in both physiological and pathological conditions, including acute kidney injury. However, the roles of lncRNA dysregulation in the pathogenesis of contrast-induced acute kidney injury (CI-AKI) are largely unknown. In the present study, the expression profiles of lncRNAs in kidney tissue were compared between rats with CI-AKI and controls using high-throughput RNA sequencing. In total, 910 differentially expressed (DE) lncRNAs (DElncRNAs), including 415 downregulated and 495 upregulated lncRNAs, were identified at 12 h after intra-arterial iodinated contrast medium injection (fold change ≥2; P<0.05). Eight DElncRNAs were further selected and validated using reverse transcription-quantitative polymerase chain reaction. A previous study defined microRNA (miRNA) and mRNA expression changes in the same CI-AKI model. In the present study, a lncRNA-mRNA co-expression network comprising 349 DElncRNAs and 202 DEmRNAs was constructed. The function of these DElncRNAs was mainly associated with oxidative stress and inflammation. Additionally, lncRNA-associated competing endogenous RNA (ceRNA) analysis revealed a network comprising 40 DElncRNA nodes, 5 DEmiRNA nodes and 59 DEmRNA nodes. Among which, the carnosine dipeptidase 1-specific and the transmembrane protein 184B-specific networks were likely to be associated with CI-AKI. The results of the present study revealed the expression profile and potential roles of lncRNAs in CI-AKI, and provide a framework for further mechanistic studies.

Neuroimaging Considerations in Patients with Chronic Kidney Disease

Chronic Kidney Disease is a common medical condition that frequently overlaps with neurologic disease. Neuroimaging can be a useful tool to aid in the diagnoses of neurologic illness, including those that result from renal impairment. Some neuroimaging studies also have the potential to lead to adverse effects on the kidneys necessitating a thoughtful approach to selection of imaging modalities. In particular, multimodal imaging is becoming increasingly common in patients presenting with symptoms of acute stroke, a population that may be at higher risk for renal complications. This article will summarize the neuroimaging manifestations of conditions with shared renal and neurologic involvement and highlight considerations regarding the use of contrast media, nephrogenic systemic fibrosis, and metformin-associated lactic acidosis.

Acute Kidney Injury After Radiocontrast-Enhanced Computerized Tomography in Hospitalized Patients With Advanced Renal Failure: A Propensity-Score-Matching Analysis

BACKGROUND

The overall risk of postcontrast acute kidney injury (PC-AKI) after computerized tomography (CT) is negligible, likely because of the small volume of injected iodinated contrast media required. However, the safety of contrast media-enhanced CT in patients with advanced renal functional impairment, an established major risk factor for PC-AKI, is unknown.

MATERIALS AND METHODS

This is a retrospective study using large data analysis of hospitalized patients at a single center. Adults undergoing CT or magnetic resonance imaging were included in the study and were stratified by estimated glomerular filtration rate (eGFR) (≤30 or >30 mL/min/1.73 m) and by either contrast-enhanced or nonenhanced imaging. Only patients with serial determination of creatinine before and after imaging were included. Demographic, clinical, and laboratory data between groups were analyzed and compared using univariate analysis, propensity score matching, and multivariate logistic regression analysis.

RESULTS

A total of 22,319 imaging studies were included. Patients with an eGFR of 30 mL/min/1.73 m or lower undergoing contrast-enhanced CT (n = 403) had an increased risk to develop PC-AKI than did similar patients undergoing enhanced or nonenhanced magnetic resonance imaging (n = 96) or nonenhanced CT (n = 1576) or patients undergoing contrast-enhanced CT with a preprocedural eGFR higher than 30 mL/min/1.73 m (n = 9173). These findings remained robust after propensity matching for demographic, procedural, and clinical parameters. Multivariate regression analysis of all patients undergoing CT with preimaging eGFR of 30 mL/min or lower (n = 1979) revealed that iodine-based contrast enhancement increased the likelihood of post-CT AKI by 51% (confidence interval, 1.23-2.05).

CONCLUSION

Although radiocontrast-enhanced CT is considered safe in most hospitalized patients and in ambulatory settings, the risk of PC-AKI remains significant among inpatients with substantial preimaging renal functional impairment. Caution is warranted using iodine-based enhanced CT in hospitalized patients with an eGFR of 30 mL/min/1.73 m or lower.

The association between neutrophil-to-lymphocyte ratio and contrast-induced acute kidney injury in patients with carotid artery stenting

OBJECTIVES

Contrast-induced acute kidney injury (CI-AKI) is a life-threatening complication that leads to comorbidities and prolonged hospital stay lengths in the setting of peripheral interventions. The presence of some CI-AKI risk factors has already been investigated. In this study, we evaluated the predictors of CI-AKI after carotid artery stenting.

METHODS

A total of 389 patients with 50% to 99% carotid artery stenosis who underwent carotid artery stenting were included in this study. Patients were grouped according to CI-AKI status.

RESULTS

CI-AKI developed in 26 (6.6%) patients. Age, baseline creatinine level, neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio were higher and estimated glomerular filtration rate, haemoglobin and lymphocyte count were lower in CI-AKI patients. In the multivariate regression analysis, the neutrophil-to-lymphocyte ratio triggered a 1.39- to 2.63-fold increase in the risk of CI-AKI onset (p < 0.001).

CONCLUSIONS

The neutrophil-to-lymphocyte ratio may be a significant predictor of CI-AKI in patients with carotid artery stenting and higher neutrophil-to-lymphocyte ratio values may be independently associated with CI-AKI.

Sodium Bicarbonate in Different Critically Ill Conditions: From Physiology to Clinical Practice

Intravenous sodium bicarbonate is commonly used in several critically ill conditions for the management of acute acidemia independently of the etiology, and for the prevention of acute kidney injury, although this is still controversial from a physiologic point of view.

Use of Anti-Diabetic Agents in Non-Diabetic Kidney Disease: From Bench to Bedside

New drugs were recently developed to treat hyperglycemia in patients with type 2 diabetes mellitus (T2D). However, metformin remains the first-line anti-diabetic agent because of its cost-effectiveness. It has pleiotropic action that produces cardiovascular benefits, and it can be useful in diabetic nephropathy, although metformin-associated lactic acidosis is a hindrance to its use in patients with kidney failure. New anti-diabetic agents, including glucagon-like peptide-1 receptor (GLP-1R) agonists, dipeptidyl peptidase-4 (DPP-4) inhibitors, and sodium-glucose transporter-2 (SGLT-2) inhibitors, also produce cardiovascular or renal benefits in T2D patients. Their glucose-independent beneficial actions can lead to cardiorenal protection via hemodynamic stabilization and inflammatory modulation. Systemic hypertension is relieved by natriuresis and improved vascular dysfunction. Enhanced tubuloglomerular feedback can be restored by SGLT-2 inhibition, reducing glomerular hypertension. Patients with non-diabetic kidney disease might also benefit from those drugs because hypertension, proteinuria, oxidative stress, and inflammation are common factors in the progression of kidney disease, irrespective of the presence of diabetes. In various animal models of non-diabetic kidney disease, metformin, GLP-1R agonists, DPP-4 inhibitors, and SGLT-2 inhibitors were favorable to kidney morphology and function. They strikingly attenuated biomarkers of oxidative stress and inflammatory responses in diseased kidneys. However, whether those animal results translate to patients with non-diabetic kidney disease has yet to be evaluated. Considering the paucity of new agents to treat kidney disease and the minimal adverse effects of metformin, GLP-1R agonists, DPP-4 inhibitors, and SGLT-2 inhibitors, these anti-diabetic agents could be used in patients with non-diabetic kidney disease. This paper provides a rationale for clinical trials that apply metformin, GLP-1R agonists, DPP-4 inhibitors, and SGLT-2 inhibitors to non-diabetic kidney disease.

Efficacy of Alprostadil in Preventing Contrast-Induced Nephropathy: A Systematic Review and Meta-Analysis

This study aimed to determine the efficacy of alprostadil in preventing contrast-induced nephropathy (CIN). Eligible studies were searched using the keywords through the databases of PubMed, Cochrane, Embase, China Biological Medicine Database, China National Knowledge Infrastructure, and Vanfun. Quality evaluation of the included studies was conducted according to international evidence evaluation and recommended Grades of Recommendations Assessment, Development, and Evaluation standards. We included 29 studies with 5623 patients. Compared with hydration, 10 µg/d alprostadil or 20 µg/d alprostadil plus hydration significantly decreased the incidence of CIN. Compared with hydration, alprostadil plus hydration significantly reduced serum creatinine and blood urea nitrogen at 24, 48, and 72 hours and 7 days after coronary angiography (CAG). Alprostadil (20 µg/d) plus hydration significantly decreased serum cystatin versus hydration at 24, 48, and 72 hours after CAG. Compared with hydration, alprostadil plus hydration significantly increased glomerular filtration rate at 24 and 72 hours after CAG. Alprostadil plus hydration significantly decreased neutrophil gelatinase-associated lipocalin levels compared to hydration at 24, 48, and 72 hours after CAG. Alprostadil plus hydration significantly decreased urine macroglobulin versus hydration at 24 and 48 hours after CAG.

RenalGuard system and conventional hydration for preventing contrast-associated acute kidney injury in patients undergoing cardiac interventional procedures: A systematic review and meta-analysis

BACKGROUND

Contrast-associated acute kidney injury (CA-AKI) can increase the mortality of patients undergoing transcatheter aortic valve replacement (TAVR) or percutaneous coronary intervention (PCI). The purpose of this paper was to compare the efficacy of the RenalGuard System and conventional hydration regimen in preventing CA-AKI in patients with TAVR or PCI.

METHODS

We searched PubMed, Embase, Web of Science, and the Cochrane Central Register of Clinical Trials (last updated July 11, 2020) for suitable reports. The primary outcome was the occurrence of CA-AKI. The secondary outcomes were renal replacement therapy (RRT), major cardiovascular events (MACEs), and other adverse complications.

RESULTS

The search strategy yielded 270 studies (with data for 2067 participants). In the subgroup of PCI, low incidence of CA-AKI (6.7% vs 15.7%; 95%CI: 0.27 to 0.54; I² = 8%; P < 0.00001) associate with RenalGuard group (RG) rather than control group (CG). Similarly, in the subgroup of TAVR, a low incidence of CA-AKI (15.6% vs 26.9%; 95%CI: 0.35 to 0.82; I² = 88%; P = 0.004) relates to RG. However, this result is highly heterogeneous. Compare with conventional hydration, RenalGuard significantly reduce the incidence of pulmonary edema (1.5%vs4.1%; 95%CI: 0.18 to 0.72; I² = 0%; P = 0.004).

CONCLUSIONS

RenalGuard System can lessen the risk of CA-AKI and RRT in patients undergoing PCI. But for patients experiencing TAVR, due to unique hemodynamic effects, the role of RenalGuard remains questionable. RenalGuard is more secure than conventional hydration. Future work should elucidate the feasibility and safety of this prophylactic intervention in cardiac interventional therapy.

Ferrotoxicity and Its Amelioration by Calcitriol in Cultured Renal Cells

Globally, acute kidney injury (AKI) is associated with significant mortality and an enormous economic burden. Whereas iron is essential for metabolically active renal cells, it has the potential to cause renal cytotoxicity by promoting Fenton chemistry-based oxidative stress involving lipid peroxidation. In addition, 1,25-dihydroxyvitamin D3 (calcitriol), the active form of vitamin D, is reported to have an antioxidative role. In this study, we intended to demonstrate the impact of vitamin D on iron-mediated oxidant stress and cytotoxicity of Vero cells exposed to iohexol, a low osmolar iodine-containing contrast media in vitro. Cultured Vero cells were pretreated with 1,25-dihydroxyvitamin D3 dissolved in absolute ethanol (0.05%, 2.0 mM) at a dose of 1 mM for 6 hours. Subsequently, iohexol was added at a concentration of 100 mg iodine per mL and incubated for 3 hours. Total cellular iron content was analysed by a flame atomic absorption spectrophotometer at 372 nm. Lipid peroxidation was determined by TBARS (thiobarbituric acid reactive species) assay. Antioxidants including total thiol content were assessed by Ellman’s method, catalase by colorimetric method, and superoxide dismutase (SOD) by nitroblue tetrazolium assay. The cells were stained with DAPI (4 ${}^{\prime }$ ,6-diamidino-2-phenylindole), and the cytotoxicity was evaluated by viability assay (MTT assay). The results indicated that iohexol exposure caused a significant increase of the total iron content in Vero cells. A concomitant increase of lipid peroxidation and decrease of total thiol protein levels, catalase, and superoxide dismutase activity were observed along with decreased cell viability in comparison with the controls. Furthermore, these changes were significantly reversed when the cells were pretreated with vitamin D prior to incubation with iohexol. Our findings of this in vitro model of iohexol-induced renotoxicity lend further support to the nephrotoxic potential of iron and underpin the possible clinical utility of vitamin D for the treatment and prevention of AKI.

Ferrotoxicity and Its Amelioration by Calcitriol in Cultured Renal Cells

Globally, acute kidney injury (AKI) is associated with significant mortality and an enormous economic burden. Whereas iron is essential for metabolically active renal cells, it has the potential to cause renal cytotoxicity by promoting Fenton chemistry-based oxidative stress involving lipid peroxidation. In addition, 1,25-dihydroxyvitamin D3 (calcitriol), the active form of vitamin D, is reported to have an antioxidative role. In this study, we intended to demonstrate the impact of vitamin D on iron-mediated oxidant stress and cytotoxicity of Vero cells exposed to iohexol, a low osmolar iodine-containing contrast media in vitro. Cultured Vero cells were pretreated with 1,25-dihydroxyvitamin D3 dissolved in absolute ethanol (0.05%, 2.0 mM) at a dose of 1 mM for 6 hours. Subsequently, iohexol was added at a concentration of 100 mg iodine per mL and incubated for 3 hours. Total cellular iron content was analysed by a flame atomic absorption spectrophotometer at 372 nm. Lipid peroxidation was determined by TBARS (thiobarbituric acid reactive species) assay. Antioxidants including total thiol content were assessed by Ellman's method, catalase by colorimetric method, and superoxide dismutase (SOD) by nitroblue tetrazolium assay. The cells were stained with DAPI (4',6-diamidino-2-phenylindole), and the cytotoxicity was evaluated by viability assay (MTT assay). The results indicated that iohexol exposure caused a significant increase of the total iron content in Vero cells. A concomitant increase of lipid peroxidation and decrease of total thiol protein levels, catalase, and superoxide dismutase activity were observed along with decreased cell viability in comparison with the controls. Furthermore, these changes were significantly reversed when the cells were pretreated with vitamin D prior to incubation with iohexol. Our findings of this in vitro model of iohexol-induced renotoxicity lend further support to the nephrotoxic potential of iron and underpin the possible clinical utility of vitamin D for the treatment and prevention of AKI.

Association between urine pH and risk of contrast-associated acute kidney injury among patients after emergency percutaneous coronary intervention: a V-shape relationship?

Aim

We investigated whether perioperative urine pH was associated with contrast-associated acute kidney injury (CA-AKI) in patients undergoing emergency percutaneous coronary intervention (PCI).

Methods

The study enrolled 1109 consecutive patients undergoing emergency PCI. Patients were divided into three groups based on perioperative urine pH (5.0–6.0, 6.5– 7.0, 7.5–8.5). The primary endpoint was the development of CA-AKI, defined as an absolute increase ≥ 0.3 mg/dL or a relative increase ≥ 50% from baseline serum creatinine within 48 h after contrast medium exposure.

Results

Overall, 181 patients (16.3%) developed contrast-associated acute kidney injury. The incidences of CA-AKI in patients with urine pH 5.0–6.0, 6.5–7.0, and 7.5–8.5 were 19.7%, 9.8%, and 23.3%, respectively. After adjustment for potential confounding factors, perioperative urine pH 5.0–6.0 and 7.5–8.5 remained independently associated with CA-AKI [odds ratio (OR)1.86, 95% confidence interval (CI) 1.25–2.82, P = 0.003; OR 2.70, 95% CI 1.5–4.68, P < 0.001, respectively]. The association was consistent in subgroups of patients stratified by several CA-AKI risk predictors. However, the risk of CA-AKI associated with urine pH 7.5–8.5 was stronger in patients with worse renal function (estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73m²) (HR 5.587, 95% CI 1.178–30.599 vs. HR 2.487, 95% CI 1.331–4.579; overall interaction P < 0.05).

Conclusion

The urine pH and CA-AKI may underlie the V-shape relationship.

The renoprotective effects of Heme Oxygenase-1 during contrast-induced acute kidney injury in preclinical diabetic models

OBJECTIVES

Contrast-induced acute kidney injury (CI-AKI) is an important clinical problem that can be aggravated by diabetes mellitus, a major risk factor. However, heme oxygenase-1 (HO-1), a promising therapeutic target, can exert antioxidant effects against CI-AKI. Thus, we investigated the role of HO-1 in CI-AKI in the presence of diabetes mellitus.

METHODS

Twenty-eight male Wistar rats weighing 250-300g were subjected to left uninephrectomy, and concomitantly, diabetes induced by streptozotocin (65 mg/kg). After 12 weeks, iodinated contrast (meglumine ioxithalamate, 6 mL/kg) and hemin (HO-1 inducer-10 mg/k) were administered 60 min before iodinated contrast treatment. The rats were randomly divided into four groups: control, diabetes mellitus (DM), DM iodinated contrast (DMIC), and DMIC hemin (DMICH). Kidney function, albuminuria, oxidative profile, and histology were assessed. All experimental data were subjected to statistical analyses.

RESULTS

CI-AKI in preclinical diabetic models decreased creatinine clearance and increased urinary neutrophil gelatinase-associated lipocalin (NGAL) levels and the degree of albuminuria. Additionally, the levels of oxidative and nitrosative stress metabolites (urinary peroxides, thiobarbituric acid-reactive substances, and NO) were elevated, while thiol levels in kidney tissue were reduced. Kidney histology showed tubular cell vacuolization and edema. HO-1 inducer treatment improved kidney function and reduced urinary the NGAL levels. The oxidative profile showed an increase in the endogenous thiol-based antioxidant levels. Additionally, the tubular injury score was reduced following HO-1 treatment.

CONCLUSIONS

Our findings highlight the renoprotective effects of HO-1 in CI-AKI and preclinical diabetic models. Therefore, HO-1 ameliorates kidney dysfunction, reduces oxidative stress, and prevents cell necrosis.

Ranolazine alleviates contrast-associated acute kidney injury through modulation of calcium independent oxidative stress and apoptosis

This study investigates the role of ranolazine in contrast-associated acute kidney injury (CA-AKI) and potential mechanisms. For in vivo studies, mouse models of CA-AKI and control mice were treated with ranolazine or vehicle. Blood urea nitrogen (BUN) and serum creatinine were detected by spectrophotometry. Anti-T-cell immunoglobulin and mucin domain 1 (TIM 1) and anti-lipocalin 2 antibody (LCN2) were detected by immunofluorescence. Hemodynamic parameters were detected via invasive blood pressure measurement and renal artery color doppler ultrasound, capillary density was measured by CD31 immunofluorescence, vascular permeability assay was performed by Evans blue dye. The expressions of oxidative stress and apoptotic markers were measured and analyzed by immunofluorescence and western blotting. For in vitro studies, intracellular calcium concentration of HUVECs was measured with Fluo 3-AM under confocal microscopy. Results show that compared with control mice, serum BUN, creatinine, TIM 1 and LCN2 levels were elevated in CA-AKI mice, but this effect was alleviated by ranolazine-pretreatment. Safe doses of ranolazine (less than 64 mg/kg) had no significant effect on overall blood pressure, but substantially improved renal perfusion, reduced contrast-induced microcirculation disturbance, improved renal capillary density and attenuated renal vascular permeability in ranolazine-pretreated CA-AKI mice. Mechanistically, ranolazine markedly down-regulated oxidative stress and apoptosis markers compared to CA-AKI mice. Intracellularly, ranolazine attenuated calcium overload in HUVECs. These results indicate that ranolazine alleviates CA-AKI through modulation of calcium independent oxidative stress and apoptosis.

Could sST2 Predict Contrast-Induced Nephropathy in ST-Segment Elevation Myocardial Infarction?

Background and Aim

One of the most worrying complications of primary percutaneous coronary interventions is contrast-induced nephropathy (CIN) that is associated with increased mortality and morbidity in myocardial infarction. In this study, we questioned whether soluble suppression of tumorigenesis-2 (sST2), which has thought to play a role in inflammatory processes, cardiac remodeling, and fibrosis could give an idea about the development of CIN in ST-elevation myocardial infarction (STEMI) patients.

Patients and Methods

This study is a cross-sectional observational study and includes 357 consecutive STEMI patients. Demographic features, medical history, laboratory parameters, and procedural characteristics were compared according to CIN's development. The multivariate logistic regression analysis was selected to detect independent risk factors of CIN.

Results

In the study, 81 patients (22.7%) who developed CIN were identified. The concentration of sST2 in CIN (+) group was higher than that of CIN (-) group (40.6±21.0 ng/mL vs 31.5±13.0 ng/L, p<0.001). Independent predictors of CIN development were diabetes mellitus (OR, 2.059; 95% CI, 1.093-3.879; p=0.025), eGFR (OR, 0.983; 95% CI, 0.972-0.995; p=0.006), lower systolic blood pressure (OR, 0.976; 95% CI, 0.960-0.993; p=0.006), total procedure time (OR, 1.030; 95% CI, 1.011-1.049; p=0.002), and sST2 (OR, 1.101; 95% CI; 1.046-1.160; p<0.001). Besides, the risk of developing CIN in the high sST2 group is 3.06 times higher than the low group sST2 group regardless of other risk factors.

Conclusion

sST2 levels on admission in STEMI patients are useful in predicting CIN development.

Reduced glutathione does not further reduce contrast-induced nephropathy in elderly patients with diabetes receiving percutaneous coronary intervention

Objective

To investigate the preventive effect of hydration combined with reduced glutathione on contrast-induced nephropathy (CIN) after coronary intervention therapy in elderly Chinese patients with diabetes.

Methods

Patients with diabetes aged ≥65 years, who received percutaneous coronary intervention (PCI) between 1 August 2016 and 31 December 2018, were enrolled and randomized into two groups: patients treated with hydration combined with reduced glutathione (treatment group) and patients who received hydration alone (controls). Serum creatinine and creatinine clearance levels were measured in all patients before PCI and then daily for 3 days after PCI. Occurrence of CIN (the primary endpoint) was defined as serum creatinine value 25% or 44.2 mmol/l (0.5 mg/dl) above baseline at 72 h after an exposure to contrast medium.

Results

A total of 396 patients were included (treatment group, n = 204; and controls, n = 192). The CIN occurrence rate in the treatment and control group was 5.88% and 6.77%, respectively, with no statistically significant between-group difference.

Conclusion

In elderly patients with diabetes receiving PCI, the risk of CIN was not effectively lowered by hydration combined with reduced glutathione.

Five-year follow-up of patients with radio-contrast-induced acute renal injury. Can intravenous sodium-bicarbonate improve long-term outcomes?

BACKGROUND/PURPOSE

Radiocontrast-induced acute kidney injury (RAKI) is a frequent complication during angiography and is associated with adverse prognosis. Most of the studies evaluating the long-term outcome of patients with RAKI are based on institutional registries. This is the first prospective study to evaluate the 5-year outcomes of patients with RAKI, and assess the effect of sodium bicarbonate (SB) in the long-term outcomes of patients with chronic kidney disease (CKD) undergoing non-emergent coronary angiography.

MATERIALS/METHODS

382 CKD stage III-IV patients undergoing elective non-emergent coronary angiography were randomized to SB (n = 192) or normal saline (NS) solution (n = 190). Incidence of RAKI, in-hospital, 1- and 5-year mortality and renal replacement therapy (RRT), and 5-year major adverse renal and cardiovascular events (MARCE) were compared between groups. Outcomes of patient with and without RAKI were compared after five-years of prospective follow-up. Multivariate predictors of RAKI and death at 5-years were determined.

RESULTS

The use of SB did not improve the incidence of RAKI, in-hospital outcomes, survival, and freedom from RRT or MARCE after 5-years of follow-up. Patients that developed RAKI had a significantly higher mortality at 1-year [8.9% Vs. 1.2%] and 5-years (36% Vs. 11%) (P < 0.01).

CONCLUSIONS

Hydration with SB showed no benefit compared to NS in preventing RAKI. The use of SB was not superior to NS after 5-years of follow-up regarding MARCE, survival or freedom of RRT. Five-year mortality among patients who developed RAKI remains high, and further research is needed to find the best preventive strategy for this high-risk group of patients.

SUMMARY

Radiocontrast-induced acute-kidney-injury (RAKI) is associated with poor long-term outcomes in observational and short-term studies. Hydration with sodium bicarbonate (SB) had been evaluated in the prevention of RAKI; but its long-term effect has not been evaluated. We randomized 382 high high-risk patients undergoing coronary angiography to SB or normal saline following them for five years. SB showed no benefit in preventing RAKI, decreasing major adverse renal and cardiovascular events, improving survival or freedom from dialysis after 5-years. This is the first study to follow patients with RAKI for a period of 5-years, showing a significantly higher mortality in this group of patients.

Contrast-induced nephropathy and oxidative stress: mechanistic insights for better interventional approaches

Contrast-induced nephropathy (CIN) or contrast-induced acute kidney injury (CI-AKI) is an iatrogenic acute kidney injury observed after intravascular administration of contrast media for intravascular diagnostic procedures or therapeutic angiographic intervention. High risk patients including those with chronic kidney disease (CKD), diabetes mellitus with impaired renal function, congestive heart failure, intraarterial intervention, higher volume of contrast, volume depletion, old age, multiple myeloma, hypertension, and hyperuricemia had increased prevalence of CIN. Although CIN is reversible by itself, some patients suffer this condition without renal recovery leading to CKD or even end-stage renal disease which required long term renal replacement therapy. In addition, both CIN and CKD have been associated with increasing of mortality. Three pathophysiological mechanisms have been proposed including direct tubular toxicity, intrarenal vasoconstriction, and excessive production of reactive oxygen species (ROS), all of which lead to impaired renal function. Reports from basic and clinical studies showing potential preventive strategies for CIN pathophysiology including low- or iso-osmolar contrast media are summarized and discussed. In addition, reports on pharmacological interventions to reduce ROS and attenuate CIN are summarized, highlighting potential for use in clinical practice. Understanding this contributory mechanism could pave ways to improve therapeutic strategies in combating CIN.

Low contrast volume dual-energy CT of the chest: Quantitative and qualitative assessment

PURPOSE

To evaluate the image quality of chest CT performed on dual-energy scanners using low contrast volume for routine chest (DECT-R) and pulmonary angiography (DECTPA) protocols.

MATERIALS AND METHODS

This retrospective study included dual-energy CT scans of chest performed with low contrast volume in 84 adults (34M:50F; Age 69 ± 16 years: Weight 71 ± 16kg). There were 42 patients with DECT-R and 42 patients with DECT-PA protocols. Images were reviewed by two thoracic radiologists. Qualitative assessment was done on a four-point scale, for subjective assessment of contrast enhancement and artifacts (1 = Excellent, 2 = optimal, 3 = suboptimal, and 4 = Limited) in the pulmonary arteries and thoracic aorta, on virtual monoenergetic and material decomposition iodine (MDI) images. Quantitative assessment was performed by measuring the CT (Hounsfield) units in aorta and pulmonary arteries. The estimated glomerular filtration rate (eGFR) was calculated before and after CT scans. Two tailed student's t-test was performed to assess the significance of findings, and strength of correlation between readers was determined by Cohen's kappa test.

RESULTS

DECT-PA and DECT-R demonstrated excellent/adequate contrast density within the pulmonary arteries (up to segmental branch), and aorta. There was no suboptimal or limited examination. There was strong interobserver agreement for arterial enhancement in pulmonary arteries (kappa = 0.62-0.89) and for thoracic aorta (kappa = 0.62-0.94). Pulmonary emboli were seen in 3/42(7%) in DECT-R and in 5/42(12%) in DECT-PA. There was no significant change in eGFR before and after IV contrast injection (p = 0.46-0.52).

CONCLUSION

DECT-R and DECT-PA performed with low contrast volume provide diagnostic quality opacification of the pulmonary vessels and aorta vessels.

Preventing contrast-induced nephropathy (CIN) with herbal medicines: A review

OBJECTIVES

Currently, the use of iodinated contrast media in diagnostic imaging has been increased in clinical medicine. Contrast-induced nephropathy (CIN) is an important adverse effect of contrast media injection. According to the significant role of oxidative stress in the pathophysiology of CIN, different herbal antioxidants have been used for the prevention of nephropathy in different studies. In this review, we discussed the preventive effects of herbal medicine and natural products against CIN.

METHODS

We searched the electronic databases or search engines including PubMed, Scopus, ISI, Google Scholar with search terms such as "Contrast-induced nephropathy" and "Herbal medicine," "Contrast acute kidney injury" AND "natural products" and similar headings such as plant and extract.

RESULTS

Known medicinal plants and active ingredients such as green tea, ginger, garlic, silymarin, curcumin, resveratrol, and thymoquinone have been examined for prophylactic effects or treatment of contrast media nephropathy.

CONCLUSION

Herbal medicines have promising effects in the laboratory-based studies for the prevention and/or treatment of CIN. However, more practical and completed clinical trials are needed to investigate the clinical benefits of natural products against CIN.

Postangiography Increases in Serum Creatinine and Biomarkers of Injury and Repair

BACKGROUND AND OBJECTIVES

It is unknown whether iodinated contrast causes kidney parenchymal damage. Biomarkers that are more specific to nephron injury than serum creatinine may provide insight into whether contrast-associated AKI reflects tubular damage. We assessed the association between biomarker changes after contrast angiography with contrast-associated AKI and 90-day major adverse kidney events and death.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a longitudinal analysis of participants from the biomarker substudy of the Prevention of Serious Adverse Events following Angiography trial. We measured injury (kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, IL-18) and repair (monocyte chemoattractant protein-1, uromodulin, YKL-40) proteins from plasma and urine samples at baseline and 2-4 hours postangiography. We assessed the associations between absolute changes and relative ratios of biomarkers with contrast-associated AKI and 90-day major adverse kidney events and death.

RESULTS

Participants (n=922) were predominately men (97%) with diabetes (82%). Mean age was 70±8 years, and eGFR was 48±13 ml/min per 1.73 m²; 73 (8%) and 60 (7%) participants experienced contrast-associated AKI and 90-day major adverse kidney events and death, respectively. No postangiography urine biomarkers were associated with contrast-associated AKI. Postangiography plasma kidney injury molecule-1 and IL-18 were significantly higher in participants with contrast-associated AKI compared with those who did not develop contrast-associated AKI: 428 (248, 745) versus 306 (179, 567) mg/dl; P=0.04 and 325 (247, 422) versus 280 (212, 366) mg/dl; P=0.009, respectively. The majority of patients did not experience an increase in urine or plasma biomarkers. Absolute changes in plasma IL-18 were comparable in participants with contrast-associated AKI (-30 [-71, -9] mg/dl) and those without contrast-associated AKI (-27 [-53, -10] mg/dl; P=0.62). Relative ratios of plasma IL-18 were also comparable in participants with contrast-associated AKI (0.91; 0.86, 0.97) and those without contrast-associated AKI (0.91; 0.85, 0.96; P=0.54).

CONCLUSIONS

The lack of significant differences in the absolute changes and relative ratios of injury and repair biomarkers by contrast-associated AKI status suggests that the majority of mild contrast-associated AKI cases may be driven by hemodynamic changes at the kidney.

Effect of Low-Frequency Therapeutic Ultrasound on Induction of Nitric Oxide in CKD: Potential to Prevent Acute Kidney Injury

Introduction

Post-contrast acute kidney injury (PC-AKI) develops in a significant proportion of patients with CKD after invasive cardiology procedures and is strongly associated with adverse outcomes.

Objective

We sought to determine whether increased intrarenal nitric oxide (NO) would prevent PC-AKI.

Methods

To create a large animal model of CKD, we infused 250 micron particles into the renal arteries in 56 ± 8 kg pigs. We used a low-frequency therapeutic ultrasound device (LOTUS - 29 kHz, 0.4 W/cm²) to induce NO release. NO and laser Doppler probes were used to assess changes in NO content and blood flow. Glomerular filtration rate (GFR) was measured by technetium-diethylene-triamine-pentaacetic acid (Tc-99m-DTPA) radionuclide imaging. PC-AKI was induced by intravenous infusion of 7 cm³/kg diatrizoate. In patients with CKD, we measured GFR at baseline and during LOTUS using Tc-99m-DTPA radionuclide imaging.

Results

In the pig model, CKD developed over 4 weeks (serum creatinine [Cr], mg/dL, 1.0 ± 0.2-2.6 ± 0.9, p < 0.01, n = 12). NO and renal blood flow (RBF) increased in cortex and medulla during LOTUS. GFR increased 75 ± 24% (p = 0.016, n = 3). PC-AKI developed following diatrizoate i.v. infusion (Cr 2.6 ± 0.7 baseline to 3.4 ± 0.6 at 24 h, p < 0.01, n = 3). LOTUS (starting 15 min prior to contrast and lasting for 90 min) prevented PC-AKI in the same animals 1 week later (Cr 2.5 ± 0.4 baseline to 2.6 ± 0.7 at 24 h, p = ns, n = 3). In patients with CKD (n = 10), there was an overall 25% increase in GFR in response to LOTUS (p < 0.01).

Conclusions

LOTUS increased intrarenal NO, RBF, and GFR and prevented PC-AKI in a large animal model of CKD, and significantly increased GFR in patients with CKD. This novel approach may provide a noninvasive nonpharmacological means to prevent PC-AKI in high-risk patients.

Role of Hypoxia in Renal Failure Caused by Nephrotoxins and Hypertonic Solutions

Hypoxia plays a role in the pathogenesis of acute kidney injury under diverse clinical settings, including nephrotoxicity. Although some nephrotoxins exert direct renal parenchymal injury, likely with consequent altered oxygenation, others primarily reduce renal parenchymal oxygenation, leading to hypoxic tubular damage. As outlined in this review, nephrotoxin-related renal hypoxia may result from an altered renal oxygen supply (cyclosporine), enhanced oxygen consumption for tubular transport (agents inducing osmotic diuresis), or their combination (nonsteroidal anti-inflammatory drugs, radiocontrast agents, and others). Most agents causing hypoxic renal injury further supress physiologic low medullary Po₂, in which a limited regional blood supply barely matches the intense regional tubular transport and oxygen consumption. The medullary tubular transport and blood supply are finely matched, securing oxygen sufficiency. Predisposition to hypoxia-mediated nephrotoxicity by medical conditions, such as chronic kidney disease or diabetes, may be explained by malfunctioning of control systems that normally maintain medullary oxygenation. However, this propensity may be diminished by hypoxia-mediated adaptive responses governed by hypoxia-inducible factors. Recent reports have suggested that inhibitors of sodium-glucose cotransporters and the administration of hypertonic saline may be added to the growing list of common therapeutic interventions that intensify medullary hypoxia, and potentially could lead to hypoxic acute kidney injury.

Hydration: Intravenous and Oral: Approaches, Principals, and Differing Regimens: Is It What Goes in or What Comes Out That Is Important?

The literature (in English) was accessed to review the evidence that administration of fluids is protective of contrast-associated acute kidney injury (CA-AKI). The evidence was evaluated with the intent of understanding mechanisms of protection. Prospective randomized trials comparing oral versus intravenous fluid, sodium chloride versus no intravenous fluid, sodium bicarbonate versus sodium chloride, and forced matched hydration versus intravenous sodium chloride provided the data. In general, the more fluid administered, the lower the incidence of CA-AKI. However, understanding the mechanism of this beneficial effect suggests that it is the urine output that most directly affects the incidence of CA-AKI.

The Mechanism of Contrast-Induced Acute Kidney Injury and Its Association with Diabetes Mellitus

Contrast-induced acute kidney injury (CI-AKI) is the third most common hospital-acquired AKI after AKI induced by renal perfusion insufficiency and nephrotoxic drugs, taking great adverse effects on the prognosis and increasing hospital stay and medical cost. Diabetes nephropathy (DN) is a common chronic complication of DM (diabetes mellitus), and DN is an independent risk factor for chronic kidney disease (CKD) and CI-AKI. The incidence of CI-AKI significantly increases in patients with renal injury, especially in DM-related nephropathy. The etiology of CI-AKI is not fully clear, and research studies on how DM becomes a facilitated factor of CI-AKI are limited. This review describes the mechanism from three aspects. ① Pathophysiological changes of CI-AKI in kidney under high-glucose status (HGS). HGS can enhance the oxidative stress and increase ROS which next causes stronger vessel constriction and insufficient oxygen supply in kidney via vasoactive substances. HGS also aggravates some ion pump load and the latter increases oxygen consumption. CI-AKI and HGS are mutually causal, making the kidney function continue to decline. ② Immunological changes of DM promoting CI-AKI. Some innate immune cells and pattern recognition receptors (PRRs) in DM and/or DN may respond to some damage-associated molecular patterns (DAMPs) formed by CI-AKI. These effects overlap with some pathophysiological changes in hyperglycemia. ③ Signaling pathways related to both CI-AKI and DM. These pathways involved in CI-AKI are closely associated with apoptosis, inflammation, and ROS production, and some studies suggest that these pathways may be potential targets for alleviating CI-AKI. In conclusion, the pathogenesis of CI-AKI and the mechanism of DM as a predisposing factor for CI-AKI, especially signaling pathways, need further investigation to provide new clinical approaches to prevent and treat CI-AKI.

Pathophysiology of Contrast-Induced Acute Kidney Injury (CIAKI)

Contrast-induced acute kidney injury (CIAKI) is a severe complication associated with the use of iodinated contrast media (CM); a sudden but potentially reversible fall in glomerular filtration rate (GFR) typically occurring 48-72 hours after CM administration. Principal risk factors related with the presentation of CIAKI are preexisting chronic kidney disease and diabetes mellitus. Studies on CIAKI present considerable complexity because of differences in CM type and dose, controversies in definition and baseline comorbidities. Despite that, it should be noted that CIAKI poses a serious health problem because it is a very common cause of hospitalacquired AKI, linked to increased morbidity and mortality and utilizing growing healthcare resources. The pathogenesis of CIAKI is heterogeneous and, thus, is incompletely understood. Three basic mechanisms appear to simultaneously occur for CIAKI development: Renal vasoconstriction and medullary hypoxia, tubular cell toxicity and reactive oxygen species formation. The relative contribution of each one of these mechanisms is unknown but they ultimately lead to epithelial and endothelial cell apoptosis and GFR reduction. Further research is needed in order to better clarify CIAKI pathophysiology and accordingly introduce effective preventive and therapeutic strategies.

The immunohistochemical and histologic effects of contrast medium on uterus, fallopian tubes and ovaries, given during hysterosalpingography: rat study

Objective:

Previous studies have shown that damage occurs to internal genital tract during hysterosalpingography (HSG). The aim was to show that endometrial and tubal epithelium underwent free radical damage during HSG in an animal model.

Material and Methods:

Forty rats were evaluated in five different groups. Two groups received ionizing radiation (15-20 miliRad three times) only. Two further groups received ionizing radiation in combination with iohexol (1-2 mL). The remaining group served as control. Groups were evaluated after seven and forty-two days. Inflammation and cellular changes were evaluated histopathologically. Cellular activity of antioxidant enzymes was assessed immunohistochemically.

Results:

Inflammation, and cellular changes were detected at certain rates in all groups (p<0.001). Glutathione reductase, catalase, superoxide dismutase, glutathione S-transferase activities were found to be increased after the HSG (p<0.001).

Conclusion:

It is obvious that the cell suffers acute and chronic damage during HSG due to both radioactivity and chemicals. Although there is a lot of research done before, there is no definitive method yet to protect against the harmful effects of iodinated contrast agents and ionizing radiation. So, new methods need to be explored to protect cells and tissues from reactive oxygen radical damage caused by HSG.

DDAH-2 alleviates contrast medium iopromide-induced acute kidney injury through nitric oxide synthase

BACKGROUND

Contrast medium-induced acute kidney injury (CI-AKI) is one of the most common causes of hospital-acquired acute renal failure. However, the pathogenesis of CI-AKI remains unclear. Asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide synthase (NOS) inhibitor that is largely metabolised by dimethylarginine dimethylaminohydroxylase (DDAH) in humans. Two isoforms of DDAH exist, namely, DDAH-1 and DDAH-2. In the present study, we examined whether the DDAH-2/ADMA/NOS pathway is involved in the pathogenesis of CI-AKI.

METHODS AND RESULTS

Exposure to the contrast medium iopromide led to increase in creatinine and blood urea nitrogen (BUN) levels, accumulation of ADMA, increase in reactive oxygen species (ROS) generation, and an inflammatory response in mice kidney tissue. The injection of adenovirus-harbouring DDAH-2 lowered renal ADMA levels and had a reno-protective effect against contrast-medium injury by decreasing cell apoptosis, ROS, and fibrosis. By contrast, contrast medium-induced renal injury was exacerbated in heterozygous DDAH-2 knockout mice. In the in vitro study, overexpression of DDAH-2 increased the levels of nitrite and intracellular cGMP, while the DDAH-2 knockdown induced the opposite effect. These findings were also observed in the in vivo sample.

CONCLUSIONS

Our findings provide the first evidence that the DDAH-2/ADMA/NOS pathway is involved in the pathogenesis of CI-AKI and that the protective effect of DDAH-2 probably arises from the modulation of NOS activity, oxidative stress, and the inflammatory process.

Pathophysiology of Contrast-Induced Acute Kidney Injury

Passing contrast media through the renal vascular bed leads to vasoconstriction. The perfusion decrease leads to ischemia of tubular cells. Through ischemia and direct toxicity to renal tubular cells, reactive oxygen species formation is increased, enhancing the effect of vasoconstrictive mediators and decreasing the bioavailability of vasodilative mediators. Reactive oxygen species formation leads to oxidative damage to tubular cells. These interacting pathways lead to tubular necrosis. In the pathophysiology of contrast-induced acute kidney injury, low osmolar and iso-osmolar agents have theoretic advantages and disadvantages; however, clinically the difference in incidence of contrast-induced acute kidney injury has not changed.

Association between copeptin and contrast-induced nephropathy in patients with ST-elevation myocardial infarction

OBJECTIVE

The aim of this study was to investigate the predictive value of copeptin levels in the development of contrast-induced nephropathy (CIN).

METHODS

A total of 274 patients diagnosed with ST-elevation myocardial infarction (STEMI) and who had undergone primary percutaneous coronary intervention were included in the study. The patients were divided into two groups according to the presence (CIN+) or absence (CIN-) of CIN. These groups were compared in terms of demographic characteristics, laboratory findings and risk factors.

RESULTS

Copeptin levels (10.68±6.43 vs. 7.07±05.53 pmol/l; p<0.001) and peak creatinine (1.46±1.20 vs. 1.03±0.20 mg/dl; p=0.005) were significantly higher in the CIN+ group than in the CIN- group. Female gender was significantly more prevalent in the CIN- group compared to the CIN+ group (19% vs. 8.6%; p<0.05). Copeptin level at hospital admission (OR: 2.36, p=0.005) was found to be an independent predictor for CIN development.

CONCLUSION

Copeptin level is an independent predictor of CIN development in patients with acute STEMI that can be detected rapidly and easily. This result indicates that physicians should be aware of the possibility of CIN development in patients with high copeptin levels and preventive measures should start early.

A Randomized Trial of Recombinant Human C1-Esterase-Inhibitor in the Prevention of Contrast-Induced Kidney Injury

OBJECTIVES

This study sought to determine the efficacy profile and safety of recombinant human C1 esterase inhibitor (rhC1INH) in the prevention of contrast-associated acute kidney injury after elective coronary angiography.

BACKGROUND

Contrast-associated acute kidney injury is caused by tubular cytotoxicity and ischemia/reperfusion injury. rhC1INH is effective in reducing renal ischemia/reperfusion injury in experimental models.

METHODS

In this placebo-controlled, double-blind, single-center trial 77 patients with chronic kidney disease were randomized to receive 50 IU/kg rhC1INH before and 4 h after elective coronary angiography or placebo. The primary outcome was the peak change of urinary neutrophil gelatinase-associated lipocalin within 48 h, a surrogate marker of kidney injury.

RESULTS

Median peak change of urinary neutrophil gelatinase-associated lipocalin was lower in the rhC1INH group (4.7 ng/ml vs. 22.5 ng/ml; p = 0.038) in the per-protocol population but not in the modified intention-to-treat analysis, and in patients with percutaneous coronary interventions (median, 1.8 ng/ml vs. 26.2 ng/ml; p = 0.039 corresponding to a median proportion peak change of 11% vs. 205%; p = 0.002). The incidence of a cystatin C increase ≥10% within 24 h was lower in the rhC1INH group (16% vs. 33%; p = 0.045), whereas the frequency of contrast-associated acute kidney injury was comparable. Adverse events during a 3-month follow-up were similarly distributed.

CONCLUSIONS

Administration of rhC1INH before coronary angiography may attenuate renal injury as reflected by urinary neutrophil gelatinase-associated lipocalin and cystatin C. The safety profile of rhC1INH was favorable in a patient population with multiple comorbidities. (Recombinant Human C1 Esterase Inhibitor in the Prevention of Contrast-induced Nephropathy in High-risk Subjects [PROTECT]; NCT02869347).

Is High Preprocedural Renal Resistive Index Sensitive Enough to Predict Iodine Contrast-Induced Nephropathy in Patients Receiving Intra-Arterial Iodinate Contrast?

PURPOSE

Renal Resistive Index (RRI) is a newly introduced sonographic index in predicting contrast-induced nephropathy (CIN) development. It has been suggested that RRI > 0.69 should be considered as a risk factor for CIN development. The present study aimed to calculate the predictive value of RRI using a cutoff point of 0.69.

METHODS

A total of 90 patients who were a candidate for coronary vessels angiography were enrolled in this study. Color Doppler ultrasonography was performed and RRI was measured. Patients were followed up for 48 hours after contrast media exposure for the CIN development. The diagnosis of CIN was based on a 25% relative rise or 0.5 mg/dL absolute rise in creatinine level. The predictive values of RRI were measured using 0.69 as a cutoff point.

RESULTS

Out of 90 patients, CIN developed in 3 patients and 17 patients had preprocedural RRI > 0.69. Of 3 patients with CIN, 1 had RRI > 0.69. Using 0.69 as the cutoff point, the measured sensitivity and specificity of RRI were 33.3% and 83.9%, respectively.

CONCLUSIONS

RRI > 0.69 is not a sensitive index in predicting the CIN development and cannot be used as an independent factor.

Hydration Strategies for Preventing Contrast-Induced Acute Kidney Injury: A Systematic Review and Bayesian Network Meta-Analysis

Aims

Many previous studies have examined the effect of different hydration strategies on prevention of contrast-induced acute kidney injury (CI-AKI), but the optimal strategy is unknown. We performed a network meta-analysis (NWM) of these previous studies to identify the optimal strategy.

Methods and Results

Web of Science, PubMed, OVID Medline, and Cochrane Library were searched from their inception dates to September 30, 2018. Randomized controlled trials (RCTs) were selected based on strict inclusion criteria, and a Bayesian NWM was performed using WinBUGS V.1.4.3. We finally analyzed 60 eligible RCTs, which examined 21,293 patients and 2232 CI-AKI events. Compared to intravenous 0.9% sodium chloride (reference), intravenous sodium bicarbonate (OR [95% CI]: 0.74 [0.57, 0.93]), hemodynamic guided hydration (0.41 [0.18, 0.93]), and RenalGuard guided hydration (0.32 [0.14, 0.70]) significantly reduced the occurrence of CI-AKI. Oral hydration and intravenous 0.9% sodium chloride were each noninferior to no hydration in preventing CI-AKI. Intravenous 0.9% sodium chloride, sodium bicarbonate, and hemodynamic guided hydration were each noninferior to oral hydration in preventing CI-AKI. Based on surface under the cumulative ranking curve values, the RenalGuard system was best (0.974) and hemodynamic guided hydration was second best (0.849).

Conclusion

There was substantial evidence to support the use of RenalGuard or hemodynamic guided hydration for preventing CI-AKI in high-risk patients, especially those with chronic kidney disease or cardiac dysfunction.

Negligible Risk of Acute Renal Failure Among Hospitalized Patients After Contrast-Enhanced Imaging With Iodinated Versus Gadolinium-Based Agents

INTRODUCTION

The potential adverse renal outcome among patients undergoing iodine-based contrast-enhanced computerized tomography (CT) has been questioned recently, given the caution undertaken in patients' selection, hydration protocols, and the low radiocontrast volume, used with advanced imaging equipment.

MATERIALS AND METHODS

This study is a retrospective assessment of renal outcome in 12,580 hospitalized patients undergoing contrast-enhanced CT, compared with 754 patients subjected to gadolinium-based magnetic resonance imaging, with subsequent propensity matching for clinical characteristics and potential risk factors.

RESULTS

The risk of postcontrast acute kidney injury (PC-AKI) was found to be negligible as compared with patients undergoing enhanced magnetic resonance imaging studies, before and after propensity matching (8% vs 7.3% rate of AKI in the nonmatched iodine-based contrast agents [IBCAs] and gadolinium-based contrast agents [GBCAs], respectively, P = 0.3, and 7% in the matched IBCA group, P = 0.9), including comparisons among subgroups with well-defined risk factors such as chronic renal failure, diabetes, older age, and hypertension. However, lower systolic blood pressure before imaging was associated with higher risk to develop PC-AKI after IBCA administration but not with GBCA (for systolic blood pressure lower than 110 mm Hg, odds ratio for AKI after IBCA was 1.49; 95% confidence interval, 1.16-1.88, and after GBCA; odds ratio, 0.12; 95% confidence interval, 0.003-0.73).

CONCLUSIONS

With the current precautions undertaken, the real-life risk of PC-AKI among inpatients undergoing CT is insignificant. Possible reasons for the diverse impact of blood pressure on the propensity to develop acute kidney failure after iodine-based but not gadolinium-based enhancement imaging are discussed.

Ethyl Vanillin Protects against Kidney Injury in Diabetic Nephropathy by Inhibiting Oxidative Stress and Apoptosis

Diabetes-induced oxidative stress and apoptosis is regarded as a critical role in the pathogenesis of diabetic nephropathy (DN). Treating diabetes-induced kidney damage and renal dysfunction has been thought a promising therapeutic option to attenuate the development and progression of DN. In this study, we investigated the renoprotective effect of ethyl vanillin (EVA), an active analogue of vanillin isolated from vanilla beans, on streptozotocin- (STZ-) induced rat renal injury model and high glucose-induced NRK-52E cell model. The EVA treatment could strongly improve the deterioration of renal function and kidney cell apoptosis in vivo and in vitro. Moreover, treating with EVA significantly decreased the level of MDA and reactive oxygen species (ROS) and stabilized antioxidant enzyme system in response to oxidative stress by enhancing the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in vivo and in vitro. Furthermore, EVA also markedly suppressed cleaved caspase-3, Bax, and nuclear transcription factor erythroid 2-related factor (Nrf2) expression in STZ-induced rats. Therefore, these results of our investigation provided that EVA might protect against kidney injury in DN by inhibiting oxidative stress and cell apoptosis.

Intravascular Iodinated Contrast Is an Independent Cause of Acute Kidney Injury Following Coronary Angiography

OBJECTIVES

Recent studies have questioned whether intravascular iodinated contrast remains an independent cause of acute kidney injury (AKI). We sought to assess whether iodinated contrast administered during coronary angiography is an independent cause of AKI.

METHODS

We identified all of the patients who underwent coronary angiography between July 1, 2015 and June 30, 2017 with a discharge diagnosis of AKI that developed within 7 days following angiography. Using chart review, we categorized patients as having multifactorial AKI if ≥1 insults other than intravascular contrast potentially contributed to kidney injury or contrast-induced AKI (CI-AKI) if the only insult was contrast administration. We compared the severity of AKI and renal function upon discharge between patients with CI-AKI and multifactorial AKI.

RESULTS

We identified 78 patients who experienced AKI within 7 days following angiography, 10 (13%) of whom had CI-AKI and 68 of whom (87%) experienced multifactorial AKI. Nine (90%) patients with CI-AKI manifested stage 1 disease, 1 (10%) had stage 2 disease, and 9 (90%) experienced full recovery of kidney function. More patients with multifactorial AKI developed stage 2 or 3 disease (42% vs 10%, χ² = 3.73, P = 0.05) and experienced either partial recovery of kidney function or persistent kidney impairment compared with patients with CI-AKI (25% vs 10%, χ² = 1.9, P = 0.17), although the latter comparison was not statistically significant.

CONCLUSIONS

The intravascular administration of iodinated contrast remains an independent cause of AKI. Compared with those with multifactorial AKI, patients with CI-AKI appear to be more likely to experience mild decrements in kidney function that recover completely.

Challenges of transarterial therapy for hepatocellular carcinoma in patients with chronic kidney disease

Poor outcomes of hepatocellular carcinomas (HCC) in chronic kidney disease (CKD) patients are well described. Transarterial therapy is the standard treatment for HCC, following which regular contrast-enhanced imaging for residual disease is recommended. CKD is considered a relative contraindication for transarterial therapy owing to renal failure.This retrospective study investigated the outcomes of transarterial therapy in HCC patients with CKD. In total, 132 HCC patients who received transarterial therapy were enrolled, of whom 36 had CKD. Most CKD patients were elderly, with mean age of diagnosis of 69.7 ± 11.4 years. Hypertension (odds ratio [OR]; 5.06; 95% confidence interval [Cl]; 1.83-13.94), hepatitis C virus carrier rate (OR; 4.12, 95% CI; 1.13-14.99) and diabetes (OR; 3.62, 95% CI; 1.22-10.72) were significant predictors for CKD in HCC patients. Post therapy, the estimated glomerular filtration rate significantly decreased 13.7% from baseline in the CKD patients (P = .03). There were more post-therapy complications than in the non-CKD group, e.g. acute renal failure and sepsis (P < .01 vs P < .01). Overall survival in the CKD group was significantly poor (10.9 ± 8.5 vs 23.5 ± 16.3 months, P < .01).The lower survival of CKD patients was unrelated to treatment modality or less contrast-enhanced imaging follow-up. Further research on patient care and factors leading to poor outcomes for CKD is needed.

Contrast Induced Acute Kidney Injury and Direct Cytotoxicity of Iodinated Radiocontrast Media on Renal Proximal Tubule Cells

The administration of intravenous iodinated radiocontrast media (RCM) to visualize internal structures during diagnostic procedures has increased exponentially since their first use in 1928. A serious side effect of RCM exposure is contrast-induced acute kidney injury (CI-AKI), which is defined as an abrupt and prolonged decline in renal function occurring 48-72 hours after injection. Multiple attempts have been made to decrease the toxicity of RCM by altering ionic strength and osmolarity, yet there is little evidence to substantiate that a specific RCM is superior in avoiding CI-AKI. RCM-associated kidney dysfunction is largely attributed to alterations in renal hemodynamics, specifically renal vasoconstriction; however, numerous studies indicate direct cytotoxicity as a source of epithelial damage. Exposure of in vitro renal proximal tubule cells to RCM has been shown to affect proximal tubule epithelium in the following manner: 1) changes to cellular morphology in the form of vacuolization; 2) increased production of reactive oxygen species, resulting in oxidative stress; 3) mitochondrial dysfunction, resulting in decreased efficiency of the electron transport chain and ATP production; 4) perturbation of the protein folding capacity of the endoplasmic reticulum (ER) (activating the unfolded protein response and inducing ER stress); and 5) decreased activity of cell survival kinases. The present review focuses on the direct cytotoxicity of RCM on proximal tubule cells in the absence of in vivo complications, such as alterations in renal hemodynamics or cytokine influence.

Left ventricular end-diastolic pressure-guided hydration for the prevention of contrast-induced acute kidney injury in patients with stable ischemic heart disease: the LAKESIDE trial

OBJECTIVES

Contrast-induced acute kidney injury (CI-AKI) is a serious complication in patients undergoing diagnostic cardiac angiography or percutaneous coronary intervention. We aimed to evaluate the preventive effects of left ventricular end-diastolic pressure (LVEDP)-guided hydration for the prevention of CI-AKI in patients with chronic kidney disease undergoing cardiac catheterization.

METHODS

This prospective randomized single-blind clinical trial enrolled 114 eligible patients with an estimated glomerular filtration rate (eGFR) of 15 < eGFR ≤ 60 mL/min/1.73 m² [according to the level-modified Modification of Diet in Renal Disease formula (MDRD)] and stable ischemic heart disease undergoing coronary procedures. The patients were randomly allocated 1:1 into the LVEDP-guided hydration group (n = 57) or the standard hydration group (n = 57). CI-AKI was defined as a greater than 25% or greater than 0.5 mg/dL (44.2 mmol/L) increase in the serum creatinine concentration compared with the baseline value. Hydration with 0.9% sodium chloride at a rate of 1 mL/kg/h (0.5 mL/kg/h if left ventricular ejection fraction < 40%) within 12 h was given to all the patients in both groups before the procedure. In the LVEDP-guided group, the hydration infusion rate was adjusted according to the LVEDP level during and after the procedure.

RESULTS

The incidence of CI-AKI was 7.01% (4/57) in the LVEDP-guided group vs 3.84% (2/52) in the standard hydration group (summary odds ratio 0.53, 95% CI 0.093-3.022; P = 0.463). Major adverse cardiac events, hemodialysis, or related deaths occurred in neither of the groups during hospitalization or the 30-day follow-up.

CONCLUSIONS

In the present study, LVEDP-guided fluid administration, by comparison with standard hydration, failed to offer protection against the risk of CI-AKI in patients with renal insufficiency undergoing coronary angiography with or without percutaneous coronary intervention.

Co-expression analysis reveals dysregulated miRNAs and miRNA-mRNA interactions in the development of contrast-induced acute kidney injury

The pathogenesis of contrast-induced acute kidney injury (CI-AKI) is incompletely understood. MicroRNAs (miRNAs) are important mediators that normally function via post-transcriptional degradation of target mRNAs. Emerging evidence indicates the appearance of differentially expressed (DE) miRNAs in CI-AKI following the injection of intravenous contrast medium. However, there are differences in the pathological mechanism and incidence of CI-AKI between intravenous and intra-arterial contrast administration. The present study aimed to investigate the critical roles of dysregulated miRNAs and their associated mRNAs in kidney injury following intra-arterial contrast medium exposure. Based on a reliable CI-AKI rat model, we conducted genome-wide miRNA and mRNA expression profiling analysis using deep sequencing. In the study, 36 DE mature miRNAs were identified (fold change > 1.5 and p value < 0.05) in the kidneys of CI-AKI rats (n = 3) compared with that in the controls (n = 3), consisting of 23 up-regulated and 13 down-regulated DE miRNAs. Bioinformatic analysis revealed that wingnut (Wnt), transforming growth factor beta (TGF-β), and 5'-AMP-activated protein kinase (AMPK) signaling pathways were most likely to be modulated by these dysregulated miRNAs. Around 453 dysregulated genes (fold change > 2.0 and p value < 0.05) were identified. Integrated analysis revealed 2037 putative miRNA-mRNA pairs with negative correlations. Among them, 6 DE miRNAs and 13 genes were selected for further quantitative real-time reverse transcription polymerase chain reaction validation (n = 6 for each group), and a good correspondence between the two techniques was observed. In conclusion, the present study provided evidence of miRNA-mRNA interactions in the development of kidney injury following an intra-arterial contrast injection. These findings provide insights into the underlying mechanisms of CI-AKI.

Contrast media (meglumine diatrizoate) aggravates renal inflammation, oxidative DNA damage and apoptosis in diabetic rats which is restored by sulforaphane through Nrf2/HO-1 reactivation

Diabetes mellitus is an independent risk factor for renal impairment in patients exposed to contrast media. It doubles the risk and decreases survival rate of contrast induced nephropathy (CIN). Sulforaphane has antioxidant properties via Nrf2 activation. The interaction of diabetes and/or sulforaphane with contrast media on Nrf2 regulation is not yet understood. Herein, diabetes was induced by a single intra-peritoneal injection of streptozotocin. Animals were then divided into five groups; control non-diabetic group; diabetic group; diabetic/sulforaphane group; diabetic/CIN group; diabetic/CIN/sulforaphane group. Animals were assessed 24 h after CIN induction. Sulforaphane improved the impaired nephrotoxicity parameters, histopathological features, and oxidative stress markers induced by contrast media (meglumine diatrizoate) in diabetic rats. Immunofluorescence detection revealed increased Nrf2 expression in kidney sections after sulforaphane pretreatment. Moreover, gene expression of Nrf2 and HO-1 were up-regulated, while IL-6 and caspase3 were down-regulated in kidney tissues of animals pretreated with sulforaphane. In NRK-52E cells, sulforaphane pretreatment significantly ameliorated the cytotoxicity of meglumine diatrizoate. However, silencing Nrf2 using small interfering RNA (siRNA) abolished the cytoprotective effects of sulforaphane. Collectively, the results of this study suggest that Nrf2/HO-1 pathway has a protective role against CIN and support the clinical implication of Nrf2 activators, such as sulforaphane, in CIN particularly in diabetic patients.

Contrast-associated acute kidney injury: does it really exist, and if so, what to do about it?

For decades, when contrast agents are administrated, physicians have been concerned because of the risk of inducing acute kidney injury (AKI). Recent literature questions the existence of AKI induced by contrast, but animal studies clearly showed harmful effects. The occurrence of contrast-associated AKI was likely overestimated in the past because of confounders for AKI. Several strategies have been investigated to reduce contrast-associated AKI but even for the most important one, hydration, there are conflicting data. Even if the occurrence rate of contrast-associated AKI is low, AKI is related to worse outcomes. Therefore, besides limiting contrast agent usage, general AKI preventive measurements should be applied in at-risk patients.

The role of nuclear factor erythroid-2-related factor 2 expression in radiocontrast-induced nephropathy

Radiocontrast-induced nephropathy (CIN) is the third most common cause of acute renal failure. The pathophysiology of CIN is related to tubular injury caused by oxidative stress, and nuclear factor erythroid-2-related factor 2 (Nrf2) is critical in coordinating intracellular antioxidative processes. We thus investigated the role of Nrf2 in CIN. CIN was established in mice and in NRK-52E cells via iohexol administration according to the protocols of previous studies. To determine the role of Nrf2 in CIN, Nrf2 expression was reduced in vivo using Nrf2 knockout (KO) mice (B6.129 × 1-Nfe2 l2tm1Ywk/J) and in vitro with siRNA treatment targeting Nrf2. Increased Nrf2 expression was observed after iohexol treatment both in vivo and in vitro. Serum creatinine at 24 h after iohexol injection was significantly higher in KO mice than in wild-type (WT) mice. Histologic examination showed that iohexol-induced tubular vacuolization and structural disruption were aggravated in Nrf2 KO mice. Significant increases in apoptosis and F4/80(+) inflammatory cell infiltration were demonstrated in KO mice compared to WT mice. In addition, the increase in reactive oxygen species after iohexol treatment was augmented by Nrf2 inhibition both in vivo and in vitro. Nrf2 may be implicated in the pathogenesis of CIN via the modulation of antioxidant, anti-apoptotic, and anti-inflammatory processes.