Systematic review of the impact of N-acetylcysteine on contrast nephropathy

Cardiological Society of India practice guidelines for angiography in patients with renal dysfunction

PREAMBLE: The potential risk of contrast-induced acute kidney injury (CI-AKI) has made utilization of coronary angiography in the work-up for the diagnosis of coronary artery disease in CKD quite low.(1) This is in contrast to increasing prevalence and severity of CAD as the serum creatinine rises.(2) In fact most CKD patients will succumb to CAD and not to ESRD.(3) Thus the judicious use of CAG/PCI in this setting is of prime importance but underused. The CSI began to develop guidelines for Indian context as most guidelines are those developed by ACC/AHA or ESC. The aim was to assist the physicians in selecting the best management strategy for an individual patient under his care based on an expert committee who would review the current data and write the guidelines with relevance to the Indian context. The guidelines were developed initially in June 2010 as an initiative of Delhi CSI. Three interventional cardiologist (SB, AS, KKS), one nephrologist (SCT) and two clinical cardiologists (ST, RG) along with Dr. Roxana Mehran (New York) and Dr. Peter McCullough (Missouri), U.S.A.; were involved in a three-way teleconference to discuss/debate the data. This was presented by SB, and over the next two hours each data subset was debated/agreed/deleted and this resulted in the "Guidelines for CAG in Renal Dysfunction Patients". These were then written and re- circulated to all for final comments. Further, these guidelines were updated and additional Task Force Members nominated by Central CSI were involved in the formation of the final CSI Guidelines. Both (Roxana Mehran and Peter McCullough) reviewed these updated Guidelines in October 2012 and after incorporating the views of all the Task Force members-the final format is as it is presented in this final document.

The Role of N--Acetylcysteine in the Prevention of Contrast-Induced Nephropathy in Patients Undergoing Peripheral Angiography

Contrast-induced nephropathy (CIN) is a leading cause of hospital-acquired acute kidney injury (AKI). N-acetylcysteine (NAC) was proposed as an effective preventative measure. As data in relation to the use of NAC for the prevention of CIN in peripheral angiography are lacking, a systematic review and meta-analysis were undertaken. A comprehensive search for the published and unpublished data was performed. Data were extracted from the eligible studies. Pooled odds ratios (ORs) were used to calculate the effect of NAC on CIN incidence. Pooled effect size estimates were used to calculate the effect of NAC on serum creatinine (SCr) postcontrast. Our results showed that NAC did not reduce CIN incidence (pooled OR 1.05; 95% confidence interval [CI] 0.38-2.88; P = .92) or the mean SCr levels (pooled weighted mean difference, 4.38; 95% CI 10.4-1.65; P = .15). In conclusion, insufficient evidence exists to recommend NAC for the prevention of CIN in patients undergoing peripheral angiography.

Role of contrast media on oxidative stress, Ca(2+) signaling and apoptosis in kidney

Contrast media (CM)-induced nephropathy is a common cause of iatrogenic acute renal failure. The aim of the present review was to discuss the mechanisms and risk factors of CM, to summarize the controlled studies evaluating measures for prevention and to conclude with evidence-based strategies for prevention. A review of the relevant literature and results from recent clinical studies as well as critical analyses of published systematic reviews used MEDLINE and the Science Citation Index. The cytotoxicity induced by CM leads to apoptosis and death of endothelial and tubular cells and may be initiated by cell membrane damage together with reactive oxygen species (ROS) and inflammation. Cell damage may be aggravated by factors such as tissue hypoxia, properties of individual CM such as ionic strength, high osmolarity and/or viscosity. Clinical studies indeed support this possibility, suggesting a protective effect of ROS scavenging with the administration of N-acetylcysteine, ascorbic acid erdosteine, glutathione and bicarbonate infusion. The interaction between extracellular Ca(2+), which plays a central role in intercellular contacts and production of ROS, and the in vitro toxicity of CM was also reviewed. The current review addresses the role of oxidative stress in the pathogenesis of CM in the kidney as well as current and potential novel treatment modalities for the prevention of neutrophil activation and CM-induced kidney degeneration in patients. ROS production through CM-induced renal hypoxia may exert direct tubular and vascular endothelial injury. Preventive strategies via antioxidant supplementation include inhibition of ROS generation or scavenging.

Prevention and management of contrast-induced acute kidney injury

OPINION STATEMENT

Contrast-induced acute kidney injury (AKI) is an important complication associated with coronary angiography, percutaneous coronary intervention, and computed tomography studies. The increasing utilization of contrast agents for imaging makes the importance of this complication even greater. Patients can be risk stratified for the risk of contrast-induced AKI by several clinical factors including hypotension, renal function, age, advanced heart failure, anemia, and diabetes mellitus. Contrast volume is also an important and modifiable risk factor for AKI. For the prevention of contrast-induced AKI, multiple approaches have been tried. The most effective prevention strategy is hydration. Normal saline has been the standard, but other options such as sodium bicarbonate may be a reasonable alternative. Further studies will be required to clarify the best preventive strategies.

Preventing radiocontrast-induced nephropathy in chronic kidney disease patients undergoing coronary angiography

Radiocontrast-induced nephropathy (RCIN) is an acute and severe complication after coronary angiography, particularly for patients with pre-existing chronic kidney disease (CKD). It has been associated with both short- and long-term adverse outcomes, including the need for renal replacement therapy, increased length of hospital stay, major cardiac adverse events, and mortality. RCIN is generally defined as an increase in serum creatinine concentration of 0.5 mg/dL or 25% above baseline within 48 h after contrast administration. There is no effective therapy once injury has occurred, therefore, prevention is the cornerstone for all patients at risk for acute kidney injury (AKI). There is a small but growing body of evidence that prevention of AKI is associated with a reduction in later adverse outcomes. The optimal strategy for preventing RCIN has not yet been established. This review discusses the principal risk factors for RCIN, evaluates and summarizes the evidence for RCIN prophylaxis, and proposes recommendations for preventing RCIN in CKD patients undergoing coronary angiography.

N-acetylcysteine for Prevention of Contrast-Induced Nephropathy: A Narrative Review

Contrast-induced nephropathy (CIN) affects in-hospital, short- and long-term morbidity and mortality. It also leads to prolonged hospital stay and increased medical cost. Given the potential clinical severity of CIN, there has been considerable interest in the development of preventative strategies to reduce the risk of contrast-induced renal deterioration in at-risk populations. A number of pharmacologic and mechanical preventive measures have been attempted, but no method other than adequate periprocedural hydration has been conclusively successful. Since its introduction in 2000, N-acetylcysteine (NAC) has been widely investigated, albeit with conflicting findings for its nephroprotection capability in patients receiving contrast media procedures. However, there is still virtually no definitive evidence of effectiveness of NAC. Although the exact mechanism responsible for the protective action of NAC from renal function deterioration remains unclear, the antioxidant and vasodilatory properties of NAC have been suggested as the main mechanisms. This review summarizes the current status of NAC as a potential agent to prevent renal functional deterioration and its limitations.

Care of the critically ill emergency department patient with acute kidney injury

Introduction. Acute Kidney Injury (AKI) is common and associated with significant mortality and complications. Exact data on the epidemiology of AKI in the Emergency Department (ED) are sparse. This review aims to summarise the key principles for managing AKI patients in the ED. Principal Findings. Timely resuscitation, goal-directed correction of fluid depletion and hypotension, and appropriate management of the underlying illness are essential in preventing or limiting AKI. There is no specific curative therapy for AKI. Key principles of secondary prevention are identification of patients with early AKI, discontinuation of nephrotoxic medication where possible, attention to fluid resuscitation, and awareness of the risks of contrast-induced nephropathy. In patients with advanced AKI, arrangements for renal replacement therapy need to be made before the onset of life-threatening uraemic complications. Conclusions. Research and guidelines regarding AKI in the ED are lacking and AKI practice from critical care departments should be adopted.

Acute kidney injury: not just acute renal failure anymore?

Until recently, no uniform standard existed for diagnosing and classifying acute renal failure. To clarify diagnosis, the Acute Dialysis Quality Initiative group stated its consensus on the need for a clear definition and classification system of renal dysfunction with measurable criteria. Today the term acute kidney injury has replaced the term acute renal failure, with an understanding that such injury is a common clinical problem in critically ill patients and typically is predictive of an increase in morbidity and mortality. A classification system, known as RIFLE (risk of injury, injury, failure, loss of function, and end-stage renal failure), includes specific goals for preventing acute kidney injury: adequate hydration, maintenance of renal perfusion, limiting exposure to nephrotoxins, drug protective strategies, and the use of renal replacement therapies that reduce renal injury.

[Contrast-induced nephropathy]

Contrast-induced nephropathy is a major complication resulting from percutaneous coronary interventional procedures characterized by acute or subacute deterioration of renal function due to exposure to iodinated contrast medium that is associated with increased morbidity and mortality. Promoting factors for the development of nephropathy have been widely described in literature as well as hydration and pharmacological measures to prevent its development; However, few of them have shown evidence level A so far, hence a major research front remains open, not only in the prevention but also in the treatment of this pathology. In this article we review epidemiological and pathophysiological aspects of this complication, and various preventive and therapeutic modalities currently available.

Contrast-induced acute kidney injury: short- and long-term implications

The intravascular administration of iodine-based contrast media remains a common cause of acute kidney injury and a leading cause of iatrogenic renal disease. Past research has elucidated the principal risk factors for contrast-induced acute kidney injury (CIAKI) and helped to establish the efficacy of various interventions for the prevention of this condition. The importance of preventing CIAKI has been underscored by a growing number of studies showing strong associations of CIAKI with serious adverse short- and long-term outcomes. However, it remains unclear whether these associations are causal. This is important because considerable health care resources are used to prevent CIAKI. If CIAKI is a marker, but not a mediator, of serious adverse downstream outcomes, more judicious and selective use of preventive care may be appropriate. Moreover, with an increasing number of studies reporting the underuse of coronary angiography in patients with acute coronary syndrome and underlying chronic kidney disease, presumably in part because of a fear of CIAKI, a clear understanding of whether this condition directly results in adverse downstream outcomes is essential. Careful inspection of past studies that investigated the association of CIAKI with adverse short- and long-term events sheds light on their strengths and weaknesses and provides insight into how future research may be better able to characterize the short- and long-term implications of this iatrogenic condition.

Acute kidney injury: current perspectives

Acute kidney injury (AKI) increases morbidity and mortality, particularly for the critically ill. Recent definitions standardizing AKI to reflect graded changes in serum creatinine and urine output (per the Risk, Injury, Failure, Loss, and End-stage renal failure [RIFLE] and Acute Kidney Injury Network [AKIN] criteria) with severity of renal injury and developments in AKI pathobiology are being utilized to identify biomarkers of early kidney injury. These developments may be useful in the early intervention of preventing AKI. Although there has been progress in the management of AKI, therapeutic challenges include appropriate prophylaxis prior to contrast administration, use of diuretics, vasopressors, and the type and dose of renal replacement therapy. Future use of bioartificial dialyzers, plasma therapies, and the possibility of stem cell regeneration of injured kidney tissue are being actively investigated to provide alternative treatment options for AKI. This review aims to provide an overview of current practices, available therapies, and continued research in AKI therapy.

Intravenous N-Acetylcysteine in the Prevention of Contrast Media-Induced Nephropathy

Objective

Ti define the clinical role of intravenous N-acetylcysteine for prophylaxis of contrast-induced nephropathy (CIN).

Data Sources:

Randomized controlled clinical trials were identified using a search of MEDLINE (1990-September 2010) with the search terms acetylcysteine, N-acetylcysteine, NAC, intravenous, IV, nephropathy, nephrotoxic, radiocontrast, contrast, and media. The search was limited to studies published in English. Additional pertinent literature was retrieved by reviewing references of the articles obtained in the initial search.

Data Synthesis:

N-Acetylcysteine is a vasodilator and antioxidant that has been investigated for the prevention of CIN. In the majority of clinical trials, neither oral nor intravenous N-acetyIcysteine has demonstrated clinical benefits at preventing CIN. The pharmacodynamic and pharmacokinetic profiles of intravenous N-acetylcysteine are significantly different from those of the oral product in that intravenous administration bypasses extensive first-pass metabolism. Studies have suggested that N-acetylcysteine directly affects serum creatinine levels in a way that is not associated with improvement of kidney function. Only intravenous N-acetylcysteine doses that were higher than the oral doses showed potential benefits, but they were associated with significant adverse events. Furthermore, the study populations were heterogeneous, including patients with various levels of kidney function and other risk factors, and the clinical definition of CIN was not well established.

Conclusions:

NO conclusive evidence has shown that intravenous N-acetyl-cysteine is safe and effective in preventing CIN. Further clinical trials to define its role are warranted.

Intravenous N-acetylcysteine plus high-dose hydration versus high-dose hydration and standard hydration for the prevention of contrast-induced nephropathy: CASIS--a multicenter prospective controlled trial

BACKGROUND

Contrast-induced nephropathy (CIN) is a leading cause of acute renal failure and affects mortality and morbidity. We investigated the efficacy of prophylactic intravenous (IV) N-acetylcysteine (NAC) and hydration for the prevention of CIN in patients with mild to moderate renal dysfunction who are undergoing coronary angiography and/or percutaneous coronary intervention (PCI).

METHODS

A total of 220 patients who had mild to moderate renal dysfunction with serum creatinine (SCr) ≥ 1.1mg/dL or creatinine clearance ≤ 60 mL/min were randomized in 3 groups: 80 patients were assigned to IV NAC plus high-dose hydration with normal saline, 80 patients to only high-dose hydration with normal saline and 60 patients to standard hydration with normal saline (control group). The primary end point was the alteration of SCr level. The secondary end point was the development of CIN after the procedure.

RESULTS

SCr levels changed the least in the NAC plus high-hydration group (P=0.004). The rate of the CIN in the NAC plus high-dose hydration group was also lower than the high-dose hydration group (P=0.006). No significant differences in the primary and secondary end points were found between high-dose hydration and control group.

CONCLUSION

The results of this study suggest that NAC plus high-dose hydration was superior to high-dose hydration alone as well as standard hydration for the protection of renal functions in patients with mild to moderate renal dysfunction who are undergoing coronary angiography and/or PCI. High-dose hydration without NAC was not better than standard hydration alone.

Evidence-based management of patients undergoing PCI: contrast-induced acute kidney injury

Contrast-induced acute kidney injury (CI-AKI) is one of the leading causes of hospital-acquired acute kidney injury. CI-AKI is highly prevalent in patients with well-known risk factors, including older age, chronic renal insufficiency, congestive heart failure, and diabetes. Thus far, no strategies have been shown to be effective in preventing CI-AKI beyond thorough patient selection, minimizing the amount of contrast agent, and meticulous hydration of the patient. The role of various drugs in preventing CI-AKI is still controversial and warrants future studies. Despite the remaining uncertainty regarding the degree of nephrotoxicity produced by various contrast agents, nonionic low-osmolar contrast media may be preferred in patients at high risk for CI-AKI.

Reactive oxygen species and the pathogenesis of radiocontrast-induced nephropathy

Experimental findings in vitro and in vivo illustrate enhanced hypoxia and the formation of reactive oxygen species (ROS) within the kidney following the administration of iodinated contrast media, which may play a role in the development of contrast media-induced nephropathy. Clinical studies indeed support this possibility, suggesting a protective effect of ROS scavenging or reduced ROS formation with the administration of N-acetyl cysteine and bicarbonate infusion, respectively. Furthermore, most risk factors, predisposing to contrast-induced nephropathy are prone to enhanced renal parenchymal hypoxia and ROS formation. In this review, the association of renal hypoxia and ROS-mediated injury is outlined. Generated during contrast-induced renal parenchymal hypoxia, ROS may exert direct tubular and vascular endothelial injury and might further intensify renal parenchymal hypoxia by virtue of endothelial dysfunction and dysregulation of tubular transport. Preventive strategies conceivably should include inhibition of ROS generation or ROS scavenging.

Effect of N-acetylcysteine on serum creatinine and kidney function: results of a randomized controlled trial

BACKGROUND

Evidence for a protective effect of N-acetylcysteine (NAC) on acute and chronic kidney disease is equivocal, and controversy persists about whether NAC affects creatinine level independently of actual kidney function. Study objectives are to investigate whether NAC affects serum creatinine level independently of alterations in other measures of kidney function.

STUDY DESIGN

Double-blind randomized controlled trial.

SETTING & PARTICIPANTS

Patients with stage 3 chronic kidney disease (n = 60), Canada, 2007-2008.

INTERVENTION

Participants were randomly allocated to receive 4 doses of oral NAC (each 1,200 mg) or placebo, administered at 12-hour intervals.

OUTCOME

The primary outcome was change in serum creatinine level between baseline and 4 hours after the last treatment dose. In addition, changes in other parameters of kidney function were measured between baseline and 4, 24, or 48 hours after the last treatment dose.

MEASUREMENTS

Serum creatinine, cystatin C, 24-hour urine protein and creatinine excretion, and creatinine clearance.

RESULTS

60 patients, mean age of 70 years, 75% men, 50% had diabetes, with mean creatinine clearance of 43.7 ± 18.8 (SD) mL/min were enrolled. Between baseline and 4 hours posttreatment, serum creatinine level decreased by 0.044 ± 0.15 mg/dL in the NAC group and 0.040 ± 0.18 mg/dL in the placebo group (95% CI for difference, -0.09 to 0.08; P = 0.9). No significant differences between groups were observed for change in serum creatinine, cystatin C, urine protein, urine creatinine, or creatinine clearance values at any time.

LIMITATIONS

Blinding patients to orally administered liquid NAC is difficult and it is possible that patients receiving NAC were not sufficiently blinded. Effects of NAC beyond 48 hours of treatment were not evaluated.

CONCLUSIONS

In this randomized controlled trial, NAC had no short-term effect on creatinine level and did not decrease urine protein excretion within 48 hours of treatment.

Prevention of acute kidney injury and protection of renal function in the intensive care unit. Expert opinion of the Working Group for Nephrology, ESICM

BACKGROUND

Acute renal failure on the intensive care unit is associated with significant mortality and morbidity.

OBJECTIVES

To determine recommendations for the prevention of acute kidney injury (AKI), focusing on the role of potential preventative maneuvers including volume expansion, diuretics, use of inotropes, vasopressors/vasodilators, hormonal interventions, nutrition, and extracorporeal techniques.

METHOD

A systematic search of the literature was performed for studies using these potential protective agents in adult patients at risk for acute renal failure/kidney injury between 1966 and 2009. The following clinical conditions were considered: major surgery, critical illness, sepsis, shock, and use of potentially nephrotoxic drugs and radiocontrast media. Where possible the following endpoints were extracted: creatinine clearance, glomerular filtration rate, increase in serum creatinine, urine output, and markers of tubular injury. Clinical endpoints included the need for renal replacement therapy, length of stay, and mortality. Studies are graded according to the international Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) group system.

CONCLUSIONS AND RECOMMENDATIONS

Several measures are recommended, though none carries grade 1A. We recommend prompt resuscitation of the circulation with special attention to providing adequate hydration whilst avoiding high-molecular-weight hydroxy-ethyl starch (HES) preparations, maintaining adequate blood pressure using vasopressors in vasodilatory shock. We suggest specific vasodilators [corrected] under strict hemodynamic control, sodium bicarbonate for emergency procedures administering contrast media, and periprocedural hemofiltration in severe chronic renal insufficiency undergoing coronary intervention.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (doi:10.1007/s00134-009-1678-y) contains supplementary material, which is available to authorized users.

Sodium bicarbonate plus N-acetylcysteine prophylaxis: a meta-analysis

OBJECTIVES

We sought to conduct a meta-analysis to compare N-acetylcysteine (NAC) in combination with sodium bicarbonate (NaHCO(3)) for the prevention of contrast-induced acute kidney injury (AKI).

BACKGROUND

Contrast-induced AKI is a serious consequence of cardiac catheterizations and percutaneous coronary interventions (PCI). Despite recent supporting evidence for combination therapy, not enough has been done to prevent the occurrence of contrast-induced AKI prophylactically.

METHODS

Published randomized controlled trial data were collected from OVID/PubMed, Web of Science, and conference abstracts. The outcome of interest was contrast-induced AKI, defined as a >or=25% or >or=0.5 mg/dl increase in serum creatinine from baseline. Secondary outcome was renal failure requiring dialysis.

RESULTS

Ten randomized controlled trials met our criteria. Combination treatment of NAC with intravenous NaHCO(3) reduced contrast-induced AKI by 35% (relative risk: 0.65; 95% confidence interval: 0.40 to 1.05). However, the combination of N-acetylcysteine plus NaHCO(3) did not significantly reduce renal failure requiring dialysis (relative risk: 0.47; 95% confidence interval: 0.16 to 1.41).

CONCLUSIONS

Combination prophylaxis with NAC and NaHCO(3) substantially reduced the occurrence of contrast-induced AKI overall but not dialysis-dependent renal failure. Combination prophylaxis should be incorporated for all high-risk patients (emergent cases or patients with chronic kidney disease) and should be strongly considered for all interventional radio-contrast procedures.

Toxicity of MRI and CT contrast agents

Anatomical and physiological imaging using CT and MRI are playing a critical role in patients' diagnosis, disease characterization and treatment planning. CT- and MRI-based protocols increasingly require an injection of iodinated CT and gadolinium (Gd)-based MRI contrast media. Although routinely used in clinical practice, iodinated and to a less extent Gd-based contrast media possess side effects: life-threatening contrast-induced nephropathy (CIN) is associated with CT and nephrogenic systemic fibrosis (NSF) with MRI contrast agents. CIN is defined as an acute decline in renal functions (serum creatinine increase > 0.5 mg/dl) after administration of iodinated contrast media. Patients with moderate-to-severe chronic kidney disease are considered the highest risk group for development of CIN. CIN is more common with ionic high-osmolar contrast CT media. NSF is a rare condition characterized by the formation of connective tissue in the skin and systemically in the lung, liver, heart and kidney. Patients with end stage kidney disease, acute kidney injury and stage 4-5 chronic kidney disease are at a high risk for NSF. The nonionic linear Gd-chelates are associated with the highest risk of NSF. This review summarizes the incidence, symptoms, safety profile of various CT and MRI contrast agents based on their physiochemical properties.

Evidence-based approach for prevention of radiocontrast-induced nephropathy

The frequency of radiocontrast administration is dramatically increasing, with over 80 million doses delivered annually worldwide. Although recently developed radiocontrast agents are relatively safe in most patients, contrast nephropathy (CN) is still a major source of in-hospital and long-term morbidity and mortality, particularly in patients with preexisting kidney disease. Multiple protocols for CN prevention have been studied; however, strict guidelines have not been established, in part because of conflicting efficacy data for most prevention approaches. In this work, we critically review the major trials that have addressed common CN prophylaxis strategies, including type of radiocontrast media, N-acetylcysteine administration, extracellular fluid volume expansion, and hemofiltration/hemodialysis. We conclude with evidence-based recommendations for CN prevention, which emphasize concurrent NaHCO3 infusion and N-acetylcysteine administration. These guidelines should be helpful to hospitalists, who frequently order radiocontrast studies, and could therefore have a significant impact on prevention of CN.

N-acetylcysteine does not prevent contrast-induced nephropathy after cardiac catheterization in patients with diabetes mellitus and chronic kidney disease: a randomized clinical trial

Background

Patients with diabetes mellitus (DM) and chronic kidney disease (CKD) constitute to be a high-risk population for the development of contrast-induced nephropathy (CIN), in which the incidence of CIN is estimated to be as high as 50%. We performed this trial to assess the efficacy of N-acetylcysteine (NAC) in the prevention of this complication.

Methods

In a prospective, double-blind, placebo controlled, randomized clinical trial, we studied 90 patients undergoing elective diagnostic coronary angiography with DM and CKD (serum creatinine ≥ 1.5 mg/dL for men and ≥ 1.4 mg/dL for women). The patients were randomly assigned to receive either oral NAC (600 mg BID, starting 24 h before the procedure) or placebo, in adjunct to hydration. Serum creatinine was measured prior to and 48 h after coronary angiography. The primary end-point was the occurrence of CIN, defined as an increase in serum creatinine ≥ 0.5 mg/dL (44.2 μmol/L) or ≥ 25% above baseline at 48 h after exposure to contrast medium.

Results

Complete data on the outcomes were available on 87 patients, 45 of whom had received NAC. There were no significant differences between the NAC and placebo groups in baseline characteristics, amount of hydration, or type and volume of contrast used, except in gender (male/female, 20/25 and 34/11, respectively; P = 0.005) and the use of statins (62.2% and 37.8%, respectively; P = 0.034). CIN occurred in 5 out of 45 (11.1%) patients in the NAC group and 6 out of 42 (14.3%) patients in the placebo group (P = 0.656).

Conclusion

There was no detectable benefit for the prophylactic administration of oral NAC over an aggressive hydration protocol in patients with DM and CKD.

Trial registration

NCT00808795

[Contrast induced nephropathy]

Contrast media induced nephropathy is a common complication, particularly in high risk patients, such as patients with chronic kidney disease (CKD) and diabetes. The majority of studies show an increased in-hospital mortality and an unfavourable long-term prognosis after manifestation of contrast media induced nephropathy. The course and the potential risk factors of this type of acute renal failure are known. Therefore, an effective prophylaxis should allow to prevent this complication. In low risk patients oral or intravenous volume expansion is probably sufficient combined with the withdrawal of non-steroidal anti-inflammatory drugs. In high risk patients additional prophylactic measures are needed but their efficacy is not clearly defined. Therefore, heterogeneous recommendations exist. Hydration reduces (afferent) renovasoconstriction, the tubuloglomerular feedback, the tubulotoxic effects of contrast media (via dilution) and the oxygen radical formation. The optimal composition, timing and amount of fluid which should be administered to the patients remain unclear. Most studies show that intravenous administration of volume is more effective than oral fluid intake. The majority of studies found a benefit of isotonic sodium bicarbonate in comparison to isotonic saline solutions, even if meta-analyses displayed only a positive trend for sodium bicarbionate due to the heterogeneity of the data. Controversies exist for N-acetylcysteine, vitamin C, fenoldopam, theophylline or statins. Due to low cost and low side effects, N-Acetylcysteine is widely used. Theophyllin (given intravenously 30 minutes before contrast media injection) is renoprotective, particularly in intensive care unit patients. Very important is the reduction of contrast media volume (if possible <30 ml for diagnostic procedures and <100 ml for interventions). Iso-osmolar and low-osmolar contrast media may have a comparable low risk for the induction of contrast media induced nephropathy. This risk is probably higher after intra-arterial as compared to intravenous administration of contrast media. Controversies exist with respect to the reduction of contrast media induced nephropathy and mortality by prophylactic hemodialysis or hemofiltration. A possible benefit of these procedures consists probably for patients with advanced chronic kidney disease (stage 5). With the further increase of investigations using contrast media, with the further increase in vascular interventions, in age and comorbidities of the patients one may suggest that the problem of contrast media induced nephropathy will further increase, despite all prophylactic procedures so far recommended.

TACE versus TAE as therapy for hepatocellular carcinoma

Transarterial chemoembolization (TACE) improves survival in cirrhotic patients with hepatocellular carcinoma (HCC). The optimal schedule, best anticancer agent and best technique are still unclear. TACE may not be better than transarterial embolization (TAE). HCC is very chemoresistant, thus embolization may be more important than chemotherapy. Lipiodol cannot be considered as an embolic agent and there are no data to show that it can release chemotherapeutic agents slowly. It can mask residual vascularity on CT imaging and its use is not recommended. Both TACE and TAE result in hypoxia, which stimulates angiogenesis, promoting tumor growth; thus combination of TACE with antiangiogenic agents may improve current results. To date, there is no evidence that TACE pre-liver transplantation or resection helps to expand current selection criteria for patients with HCC, nor results in less recurrence after surgery. Combination with other techniques, such as radiofrequency ablation and drugs, may enhance the effect of TACE. New trials are being conducted to clarify these issues.

Preventing contrast-induced nephropathy in patients with baseline renal dysfunction undergoing coronary angiography

Although contrast-induced nephropathy (CIN) is usually self-limited, it may cause permanent renal injury and even lead to long-term dialysis in patients with preexisting renal impairment. Cardiologists face a dilemma as to whether to alleviate coronary syndromes by coronary intervention or to risk CIN in these patients. Strategies to prevent CIN, including hydration, use of low-osmolal or iso-osmolal contrast media, administration of N-acetylcysteine, and blood purification procedures, were proposed to be effective; however, there are conflicting results. Recently, we found that prophylactic hemodialysis could significantly improve renal survival in patients with advanced renal insufficiency undergoing coronary angiography in a randomized controlled trial. In these patients, fluid supplementation is poorly tolerated and impractical, especially in those with poor heart function. However, the routine use of prophylactic hemodialysis in patients with mild renal insufficiency requires further investigation.

Clinical significance and preventive strategies for contrast-induced nephropathy

PURPOSE OF REVIEW

Contrast-induced nephropathy continues to be a common cause of in-hospital acute kidney injury. Published studies on pathogenesis, clinical significance, diagnosis, and preventive measures have dramatically increased significantly in the past several years. This review will focus on new developments in contrast-induced nephropathy.

RECENT FINDINGS

Studies on the clinical significance of contrast-induced nephropathy are reviewed along with initial reports of biomarkers in diagnosing this complication of iodinated contrast administration. Emerging literature on the relative nephrotoxicity of iso-osmolar versus low-osmolar contrast media and the value of bicarbonate hydration are discussed. More recent preventive measures using prostacyclin, 'statins', and erythropoietin are also reviewed.

SUMMARY

Contrast-induced nephropathy is an increasing cause of acute kidney injury and is associated with significant mortality and morbidity. Future developments in this field will focus on refining the clinical significance of this complication, earlier diagnosis with biomarkers, clarifying the role for bicarbonate and iso-osmolar contrast agents as preventive strategies, and the introduction of new prophylactic techniques on the basis of an improved understanding of pathogenesis at the cellular level.

Management of acute renal failure in the elderly patient: a clinician's guide

Numerous anatomical and functional changes occurring in the aging kidney lead to reduced glomerular filtration rate, lower renal blood flow and impaired renal autoregulation. The elderly are especially vulnerable to the development of renal dysfunction and in this population acute renal failure (ARF) is a common problem. ARF is often iatrogenic and multifactorial; common iatrogenic combinations include pre-existing renal dysfunction and exposure to nephrotoxins such as radiocontrast agents or aminoglycosides, use of NSAIDs in patients with congestive cardiac failure and use of ACE inhibitors and diuretics in patients with underlying atherosclerotic renal artery stenosis. The aetiology of ARF is classically grouped into three categories: prerenal, intrinsic and postrenal. Prerenal ARF is the second most common cause of ARF in the elderly, accounting for nearly one-third of all hospitalized cases. Common causes can be grouped into true volume depletion (e.g. decreased fluid intake), decreased effective blood volume (e.g. systemic vasodilation) and haemodynamic (e.g. renal artery stenosis, NSAID use). Acute tubular necrosis (ATN) is the most common cause of intrinsic ARF and is responsible for over 50% of ARF in hospitalized patients, and up to 76% of cases in patients in intensive care units. ATN usually occurs after an acute ischaemic or toxic event. The pathogenesis of ATN involves an interplay of processes that include endothelial injury, microvascular flow disruption, tubular hypoxia, dysfunction and apoptosis, tubular obstruction and trans-tubular back-leak. Vasculitis causing ARF should not be missed as this condition is potentially life threatening. The likelihood of a postrenal cause for ARF increases with age. Benign prostatic hypertrophy, prostatic carcinoma and pelvic malignancies are all important causes. Early identification of ARF secondary to obstruction with renal imaging is essential, and complete or partial renal recovery usually ensues following relief of the obstruction.A comprehensive medical and drug history and physical examination are all invaluable. Particular attention should be paid to the fluid status of the patient (skin turgor, jugular venous pressure, lying and standing blood pressure, urine output). Urinalysis should be performed to detect evidence of proteinuria and haematuria, which will aid diagnosis. Fractional excretion of sodium and urine osmolality may be measured but the widespread use of diuretics in the elderly gives rise to unreliable results. Renal imaging, usually ultrasound scanning, is routinely performed for assessment of renal size and to exclude urinary obstruction. In some cases, renal biopsy is necessary to provide specific diagnostic information. The general principles of managing ARF include treatment of life-threatening features such as shock, respiratory failure, hyperkalaemia, pulmonary oedema, metabolic acidosis and sepsis; stopping and avoiding administration of nephrotoxins; optimization of haemodynamic and fluid status; adjustment of drug dosage appropriate to glomerular filtration rate; early nutritional support; and early referral to nephrologists for diagnosis of ARF cause, timely initiation of dialysis and initiation of specific treatment. The treatment of prerenal and ATN ARF is largely supportive with little evidence of benefit from current pharmacological therapies. Despite advances in critical care medicine and renal replacement therapy, the mortality of ARF has not changed significantly over the last 40 years, with current mortality rates being up to 75%.

Incidence of contrast-induced nephropathy in patients with chronic renal insufficiency undergoing multidetector computed tomographic angiography treated with preventive measures

Contrast-induced nephropathy (CIN) is associated with adverse outcomes. Strategies for its prevention have been evaluated for patients undergoing invasive coronary and peripheral angiography, including treatment with N-acetylcysteine, sodium bicarbonate, and use of iso-osmolar nonionic contrast. Recently, multidetector computed tomographic angiography (MDCTA) of the coronary and peripheral arteries has been introduced as an accurate method for assessing vascular stenosis and has been widely adopted for assessment of outpatients with suspected coronary artery disease or peripheral arterial disease. To date, the incidence of CIN in outpatients with chronic renal insufficiency (CRI) treated with CIN-preventive strategies undergoing MDCTA remains unknown. Thus, we evaluated the incidence of CIN in outpatients with CRI (creatinine 1.5 to 2.5 mg/dl) undergoing MDCTA using CIN-preventive measures; 400 patients with CRI (78.5% men, mean age 76 years, 41% with diabetes) underwent MDCTA with iodixanol for detection of coronary artery disease or peripheral arterial disease (mean contrast volume 101 cc). CIN was defined as a nonallergic creatinine increase of >0.5 mg/dl. Creatinine levels were obtained before and 3 to 5 days after MDCTA; the average creatinine levels were 1.80 mg/dl and 1.75 mg/dl, respectively (p = NS), with an average change of -0.03 mg/dl. In the study cohort, only 7 patients (1.75%) experienced a creatinine increase >0.5 mg/dl, satisfying the definition of CIN. In conclusion, multivariate analysis, diabetes was the only predictor for CIN (odds ratio 5.9, 95% confidence interval 1.0 to 33.3, p = 0.045). No patient required hemodialysis. In conclusion, in patients with CRI undergoing MDCTA and receiving CIN-preventive measures, the incidence of CIN is low.

[Etiology of iodinated radiocontrast nephrotoxicity and its attenuation by beraprost]

Radiocontrast nephropathy (RCN) is a major complication after radiographical examination with iodinated contrast media (CM). Although little is known about the mechanism of RCN, a direct toxic action on renal cells and/or decrease in renal blood flow are considered to be implicated in the pathogenesis of the disease/the condition, A large number of vasodilatory agents, including endothelin antagonists, adenosine antagonists, atrial natriuretic peptide, calcium channel blockers, dopamine, dopamine D1 receptor agonist fenoldopam, and prostaglandin E1 have been tried clinically to prevent RCN, however, most of them have failed. Although prophylactic effects of antioxidant N-acetylcysteine have recently been reported by several investigators, only hydration is a universally accepted protocol to prevent it. In our recent in vitro and in vivo study, we have elucidated that CM induced apoptosis of renal tubular cells through the reduction in Bcl-2 expression and the subsequent activation of caspase-9 and caspase-3. Moreover, we found that CM caused an increase in ceramide content in renal tubular cells, which leads to apoptosis by inhibiting the phosphorylation of Akt and cAMP responsive element binding protein (CREB) and the subsequent reduction in Bcl-2 expression. The inhibitor of ceramide synthase, fumonisin B1, reversed both the elevation of ceramide content and renal cell injury induced by CM. On the other hand, a prostacyclin analog beraprost prevented RCN in mice by the increase of endogenous cAMP and subsequent CREB phosphorylation resulted in enhancement of Bcl-2 expression. These findings suggest that ceramide synthesis inhibitor or beraprost is potentially useful for the prophylaxis of RCN.

Can we prevent acute kidney injury?

OBJECTIVE

To review the literature on prevention of acute kidney injury (AKI).

DATA SOURCE

MEDLINE- and PubMed-based review of literature published from 1965 to 2007.

CONCLUSIONS

AKI is very common among critically ill patients. Even mild forms of AKI have significant attributable mortality. Hence, it is imperative that every effort to prevent AKI be made in clinical practice. However, there are very few interventions that have been shown to consistently prevent AKI. Measures such as adequate hydration, maintenance of adequate circulating blood volume and mean arterial pressure, and avoidance of nephrotoxins are still the mainstay of prevention. Loop diuretics and "renal-dose" dopamine have been clearly shown not to prevent AKI and may, in fact, do harm. Among the remaining pharmacologic options, N-acetylcysteine has the strongest evidence in prevention of AKI. Fenoldopam and theophylline need further investigation before being used to prevent septic AKI and contrast nephropathy, respectively. The role of prophylactic dialysis in preventing contrast nephropathy needs to be investigated further.

[Systemic and renal effects of preventing contrast nephrotoxicity with isotonic (0.9%) and hypotonic (0.45%) saline]

INTRODUCTION AND OBJECTIVES

Physiological and hypotonic saline solutions have been used interchangeably for preventing contrast media nephrotoxicity. No analysis of the possible differential effects of the two solutions on the milieu interieur or intercompartmental fluid volumes has been performed. Our aim was to study the systemic and renal effects of two types of saline solution regularly used to prevent contrast media nephrotoxicity in patients undergoing coronary angiography.

METHODS

Changes in electrolyte levels and volume distribution were studied in 71 individuals who were randomized to receive either 0.9% isotonic saline (n=36) or 0.45% hypotonic saline (n=35) during the 12 hours before and after contrast injection (2000 mL in each period).

RESULTS

The creatinine level was elevated equally often in the isotonic and hypotonic saline groups. Isotonic saline administration led to reductions in hemoglobin level, hematocrit and plasma albumin level, and to increases in plasma volume, by 12.3% and 10.4% at 24 and 48 hours, respectively. These changes were significant compared with baseline measurements and compared with the group that received hypotonic saline. Neither of the two saline solutions resulted in a change in plasma atrial natriuretic peptide level. Plasma and urine osmolality decreased only with hypotonic saline. The increase in plasma creatinine level was similar with both isotonic and hypotonic saline.

CONCLUSIONS

During standard therapy for preventing contrast media nephrotoxicity, (1) isotonic saline, but not hypotonic saline, increased plasma volume; (2) this increase did not raise the atrial natriuretic peptide level; and (3) no difference in the increase in serum creatinine level was observed between the two saline solutions. These findings provide evidence that 0.45% saline, at a dose suitable for preventing contrast media nephrotoxicity, is associated with a lower risk of volume expansion. This result is important for patients with severely impaired ventricular function.

A meta-analysis of N-acetylcysteine in contrast-induced nephrotoxicity: unsupervised clustering to resolve heterogeneity

BACKGROUND

Meta-analyses of N-acetylcysteine (NAC) for preventing contrast-induced nephrotoxicity (CIN) have led to disparate conclusions. Here we examine and attempt to resolve the heterogeneity evident among these trials.

METHODS

Two reviewers independently extracted and graded the data. Limiting studies to randomized, controlled trials with adequate outcome data yielded 22 reports with 2746 patients.

RESULTS

Significant heterogeneity was detected among these trials (I2 = 37%; p = 0.04). Meta-regression analysis failed to identify significant sources of heterogeneity. A modified L'Abbé plot that substituted groupwise changes in serum creatinine for nephrotoxicity rates, followed by model-based, unsupervised clustering resolved trials into two distinct, significantly different (p < 0.0001) and homogeneous populations (I2 = 0 and p > 0.5, for both). Cluster 1 studies (n = 18; 2445 patients) showed no benefit (relative risk (RR) = 0.87; 95% confidence interval (CI) 0.68-1.12, p = 0.28), while cluster 2 studies (n = 4; 301 patients) indicated that NAC was highly beneficial (RR = 0.15; 95% CI 0.07-0.33, p < 0.0001). Benefit in cluster 2 was unexpectedly associated with NAC-induced decreases in creatinine from baseline (p = 0.07). Cluster 2 studies were relatively early, small and of lower quality compared with cluster 1 studies (p = 0.01 for the three factors combined). Dialysis use across all studies (five control, eight treatment; p = 0.42) did not suggest that NAC is beneficial.

CONCLUSION

This meta-analysis does not support the efficacy of NAC to prevent CIN.