N-acetylcysteine does not prevent contrast induced nephropathy after cardiac catheterisation with an ionic low osmolality contrast medium: a multicentre clinical trial

Prospective Randomized Trial of Na/K Citrate for the Prevention of Contrast-Induced Nephropathy in High-risk Patients

Background

Contrast-induced nephropathy (CIN) or contrast-induced acute kidney injury (CI-AKI) refers to an acute kidney injury (AKI) occurring after exposure to contrast media, commonly used in diagnostic procedures or therapeutic angiographic interventions. Recently, Na/K citrate, used for urine alkalinization, has been assessed for preventing CIN. This experiment evaluated Na/K citrate's efficacy in preventing CIN in high-risk patients undergoing cardiac catheterization.

Methods

A prospective randomized clinical trial involved 400 patients with moderate- to high-risk factors for CIN undergoing elective percutaneous coronary intervention (PCI). They were randomly assigned to either the control or Na/K citrate groups. The Na/K citrate group (n = 200) received a 5 g Na/K citrate solution diluted in 200 mL water 2 hours before and 4 hours after the first administration, along with intravenous hydration for 2 hours before and 6 hours after the procedure. In contrast, the control group (n = 200) received only intravenous hydration. Serum creatinine (SCr) levels were measured before contrast exposure and 48 hours afterward. CIN was defined as a 25% increase in serum creatinine (SCr) or > 0.5 mg/dL 48 hours after contrast administration. The significance level was set at P ˂ 0.05.

Results

CIN was observed in 33 patients (16.5%) in the control group and 6 patients (3%) in the Na/K citrate group. The incidence of CIN was found to have a significant difference between the 2 groups 48 hours after receiving the radiocontrast agent (P < 0.001).

Conclusion

Our results show that Na/K citrate is helpful and substantially reduces the incidence of CIN.

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.

Latest Clinical Evidence About Effect of Acetylcysteine on Preventing Contrast-Induced Nephropathy in Patients Undergoing Angiography: A Meta-Analysis

Contrast-induced nephropathy (CIN) is a serious complication of angiographic procedures. It is the third most common cause of hospital acquired acute renal injury. As there are currently no approved therapies for CIN, prevention could be the best strategy to address this issue. Acetylcysteine may indirectly play an antioxidant role by inducing the synthesis of glutathione. Acetylcysteine can also reduce renal vasoconstriction induced by contrast medium stimulation by stabilizing nitric oxide and acting directly or indirectly on renal cortex and medulla microcirculation. To evaluate the effect of acetylcysteine on the prevention of CIN in patients after angiography, we systematically searched and analyzed the clinical data of patients including the incidence of CIN and change in serum creatinine (SCr) at 48 hours after angiography from selected articles. The result showed that acetylcysteine significantly reduces the incidence of CIN (risk ratios: 0.78, 95% CI: 0.68-0.90, I ² = 37.3%) and the level of SCr (standardized mean difference: -0.53, 95% CI: -0.93 to -0.12, I ² = 91.5%) after angiography compared with the control group. Overall, the use of acetylcysteine in patients after angiography was associated with a significant reduction of CIN and the level of SCr.

Pharmacological interventions for the prevention of contrast-induced acute kidney injury in high-risk adult patients undergoing coronary angiography: a systematic review and meta-analysis of randomised controlled trials

Objective

Quantify the efficacy of strategies to prevent contrast-induced acute kidney injury (CI-AKI) in high-risk patients undergoing coronary angiography (CAG) with or without percutaneous coronary intervention (PCI).

Background

CI-AKI remains a common problem. The renoprotective efficacy of existing pharmacological agents remains uncertain in high-risk populations.

Methods

Systematic review and meta-analysis of randomised controlled trials (RCTs) to compare different strategies versus hydration in patients with chronic kidney disease (CKD) undergoing CAG±PCI. Primary outcome was incident CI-AKI. Fixed-effects meta-analyses estimated ORs, 95% CIs and heterogeneity.

Results

Forty-eight RCTs were included. Seven pharmacological strategies were evaluated by multiple RCTs and 10 by one RCT each. These had varying risk of bias; >25% of trials were at high risk of performance bias. Five strategies significantly reduced the odds of CI-AKI: N-acetylcysteine (NAC) (27 trials, 5694 participants; OR=0.77, 95% CI 0.65 to 0.91, p=0.002, I²=36%), ascorbic acid (four trials, 759 participants; OR=0.59, 95% CI 0.39 to 0.89, p=0.01, I²=0%), statin (two trials, 3234 participants; OR=0.59, 95% CI 0.39 to 0.89, p=0.75, I²=0%), trimetazidine (two trials, 214 participants; OR=0.27, 95% CI 0.10 to 0.71, p=0.01, I²=0%) and nicorandil (two trials, 389 participants; OR=0.47, 95% CI 0.23 to 0.94, p=0.03, I²=52%). Theophylline had a similar, but non-significant, effect. A subgroup analysis found that the benefit of NAC was highest in patients requiring a high-contrast dose.

Conclusions

Several drugs are renoprotective in patients with CKD undergoing CAG±PCI. The evidence is strongest for NAC. We recommend that NAC should be used when a high dose of contrast is anticipated.

Trial registration number

PROSPERO registration CRD42014014704.

Open Science Framework link: https://osf.io/vxg7d/?view_only=62bad0404b18405abd39ff2ead2575a8

Effectiveness of contrast-associated acute kidney injury prevention methods; a systematic review and network meta-analysis

BACKGROUND

Different methods to prevent contrast-associated acute kidney injury (CA-AKI) have been proposed in recent years. We performed a mixed treatment comparison to evaluate and rank suggested interventions.

METHODS

A comprehensive Systematic review and a Bayesian network meta-analysis of randomised controlled trials was completed. Results were tabulated and graphically represented using a network diagram; forest plots and league tables were shown to rank treatments by the surface under the cumulative ranking curve (SUCRA). A stacked bar chart rankogram was generated. We performed main analysis with 200 RCTs and three analyses according to contrast media and high or normal baseline renal profile that includes 173, 112 & 60 RCTs respectively.

RESULTS

We have included 200 trials with 42,273 patients and 44 interventions. The primary outcome was CI-AKI, defined as ≥25% relative increase or ≥ 0.5 mg/dl increase from baseline creatinine one to 5 days post contrast exposure. The top ranked interventions through different analyses were Allopurinol, Prostaglandin E1 (PGE1) & Oxygen (0.9647, 0.7809 & 0.7527 in the main analysis). Comparatively, reference treatment intravenous hydration was ranked lower but better than Placebo (0.3124 VS 0.2694 in the main analysis).

CONCLUSION

Multiple CA-AKI preventive interventions have been tested in RCTs. This network evaluates data for all the explored options. The results suggest that some options (particularly allopurinol, PGE1 & Oxygen) deserve further evaluation in a larger well-designed RCTs.

A Bayesian network meta-analysis of preventive strategies for contrast-induced nephropathy after cardiac catheterization

BACKGROUND

The optimal preventive strategy for contrast induced acute kidney injury (CIAKI) in patients undergoing cardiac catheterization remains uncertain.

OBJECTIVE

We conducted Bayesian network meta-analysis (NMA) to compare different preventive strategies for CIAKI in these cohorts.

METHODS

Forty-nine randomized controlled trials were extracted using MEDLINE, EMBASE and CENTRAL data bases (inception-1st December 2017). We calculated median of the odds ratio (OR) with the corresponding 95% credible interval (CrI). The ranking probability of each treatment was based on SUCRA (surface under the cumulative ranking curve).

RESULTS

In NMA of 28,063 patients [normal saline (NS: 9716 patients), sodium bicarbonate (NaHCO3: 4484 patients), statin (2542 patients), N-acetylcysteine (NAC: 3006 patients), NAC + NaHCO3 (774 patients), NS + NAC (3807 patients), NS + NaHCO3 (135 patients) and placebo (3599 patients)], statins reduced the relative risk of CIAKI compared with NS (OR: 0.50; 95% CrI, 0.25-0.99), and placebo (OR: 0.44; 95% CrI, 0.24-0.83). Subgroup analyses showed that in patients receiving low osmolar contrast, statins reduced the relative risk of CIAKI by 58% versus NS, and 51% versus placebo. There were no significant differences across all the treatments in terms of risk of hemodialysis or all-cause mortality. Statins had the highest probability for reducing the risk of CIAKI (SUCRA, 0.86), risk of hemodialysis (SUCRA, 0.88) and all-cause mortality (SUCRA, 0.81).

CONCLUSION

Statins were the superior preventive strategy for reducing the risk of CIAKI compared with NS alone and placebo.

Allopurinol prophylactic therapy and the prevention of contrast-induced nephropathy in high-risk patients undergoing coronary angiography: A prospective randomized controlled trial

BACKGROUND

Contrast-induced nephropathy (CIN) is considered to be a possibly severe complication of radiography and thus, remains to be the main cause of acute kidney injury (AKI) for inpatients. A clinical trial was executed to measure the preventive effect of allopurinol against CIN in high-risk patients undertaking coronary angiography.

METHODS

Through randomized controlled trial, 140 patients with at minimum two risk factors of CIN, undertaking coronary angiography, were randomly allocated to the allopurinol (n = 70) or control group (n = 70). Those in the allopurinol group received allopurinol (300 mg) a day before their coronary angiography and intravenous hydration for 12 hours before and after their procedure, while members of the control group only received intravenous hydration. Serum creatinine (SCr), blood urea nitrogen (BUN) and uric acid were measured before and 48 hours after the procedure. CIN was defined by a 25% increase in SCr or the concentration of > 0.5 mg/dl, 48 hours after coronary angiography.

RESULTS

CIN was observed in 8 (11.4%) patients in the allopurinol group and 11 (15.7%) patients in the control group. There was no significant difference in the incidence of CIN between the two groups at 48 hours after coronary angiography (P = 0.459). In the allopurinol group, the median SCr concentration decreased non-significantly from 1.16 mg/dl to 1.13 mg/dl, 48 hours after coronary angiography (P = 0.189). In the control group, the median SCr concentration increased significantly from 1.11 mg/dl to 1.2 mg/dl, 48 hours after coronary angiography (P < 0.001).

CONCLUSION

Allopurinol presents no considerable effectiveness over the hydration protocol for development of CIN in high-risk patients.

Oral N-acetylcysteine for prophylaxis of contrast-induced nephropathy in patients following coronary angioplasty: A meta-analysis

It is acknowledged that contrast-induced nephropathy (CIN) is a common cause of acute renal insufficiency after cardiac catheterization and affects mortality and morbidity. To date, it is unknown whether oral N-acetylcysteine (NAC) is able to prevent contrast-induced nephropathy (CIN) in patients undergoing coronary angioplasty. A meta-analysis of randomized controlled trials was performed to assess the effects of NAC in the prevention of CIN in patients following coronary angioplasty. A total of 19 studies published prior to January 2015 that investigated the efficacy of oral NAC for the prevention of CIN were collected from Medline, Cochrane and Embase databases and conference proceedings from cardiology and nephrology meetings. The primary point of investigation was CIN, and the secondary points were renal failure requiring dialysis, mortality and length of hospitalization. The meta-analysis was performed using fixed- or random-effect models according to heterogeneity. Up to January 2015, 19 randomized placebo-controlled clinical trials met the inclusion criteria for the meta-analysis, including 4,514 patients. The pooled data showed that oral NAC did not reduce the CIN incidence [relative risk 0.84, 95% confidence interval (CI) 0.65-1.10; P=0.20], without heterogeneity among trials (I2=29%). Thus, the present meta-analysis suggests that oral NAC therapy is not effective as an alternative treatment to prevent CIN in patients following angioplasty. Further high quality randomized clinical controlled trials are required to confirm the usage and availability of this treatment.

N-Acetylcysteine and Sodium Bicarbonate Versus N-Acetylcysteine and Standard Hydration for the Prevention of Radiocontrast-Induced Nephropathy Following Coronary Angiography

Background:

Radiocontrast-induced nephropathy (RCIN) is thought to be caused by renal ischemia and direct toxic effects on renal tubular cells brought on by contrast media. The combination of N-acetylcysteine (NAC) and hydration fluids (NaCI 0.9% or 0.45%) has been shown to reduce these deleterious effects and is commonly given prior to coronary angiography. The use of bicarbonate as the hydration anion has been shown to confer additional RCIN protection compared with that of saline. However, limited data are available regarding whether sodium bicarbonate hydration, proven to be beneficial alone, can further improve outcomes when given with NAC.

Objective:

To compare the incidence of RCIN in patients undergoing coronary angiography after pretreatment with NAC plus sodium bicarbonate hydration or NAC plus standard hydration (NaCI 0.9% or 0.45%).

Methods:

A retrospective, single-center study evaluated 96 patients who underwent coronary angiography from January 2002 to December 2005. Data were collected through electronic chart reviews.

Results:

Forty-seven patients received NAC and sodium bicarbonate for hydration and 49 received NAC and standard hydration. Baseline characteristics between the 2 groups were similar. All patients received at least one 600 mg oral dose of NAC before angiography was performed. RCIN was defined as impairment of renal function occurring within 72 hours of administering contrast media, indicated by an absolute increase in the serum creatinine level of 0.5 mg/dL or more. A total of 12.2% of the patients receiving NAC and standard hydration developed RCIN, versus 14.9% of the patients in the NAC and sodium bicarbonate group (p = 0.713).

Conclusions:

The addition of sodium bicarbonate to NAC does not appear to confer additional protection against the development of RCIN. Prospective, randomized, placebo-controlled trials are warranted to definitively determine how this combination compares with NAC and standard hydration in preventing RCIN.

Effectiveness of N-Acetylcysteine for the Prevention of Contrast-Induced Nephropathy: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

Conflicting results have been obtained in trials that have evaluated the prophylactic efficacy of N‐acetylcysteine (NAC) pretreatment in the prevention of contrast‐induced nephropathy (CIN). In this meta‐analysis of randomized controlled trials, we aimed to assess the effectiveness of NAC treatment for the prevention of CIN.

Methods and Results

PubMed, EMBASE, and the Cochrane Library were electronically searched from inception to January 2016 for all relevant studies. The weighted relative risk (RR) and corresponding 95% CI for incident CIN were estimated using random effects models. Standard methods for assessing statistical heterogeneity and publication bias were used. The study included 11 480 participants and 1653 cases of CIN. The incidence of CIN was 12.8% in the NAC group versus 16.0% in the control group (RR: 0.76, 95% CI: 0.66–0.88, P=0.0002). In the patients undergoing coronary angiography, the incidence of CIN in the NAC group versus the control group was 13.7% versus 17.2% (RR: 0.74, 95% CI: 0.63–0.87, P=0.0002); in those undergoing peripheral angiography, the incidence was 6.4% versus 5.8% (RR: 1.00, 95% CI: 0.42–2.40, P=1.00); in those undergoing computed tomography, the incidence was 7.7% versus 14.8% (RR: 0.51, 95% CI: 0.29–0.89, P=0.02).

Conclusions

Our meta‐analysis showed an inverse and significant association between NAC supplementation and risk of CIN in patients undergoing coronary angiography and computed tomography, while a protective role for NAC in patients undergoing peripheral angiography was not obvious.

Strategies Preventing Contrast-Induced Nephropathy After Coronary Angiography: A Comprehensive Meta-Analysis and Systematic Review of 125 Randomized Controlled Trials

This systematic review with meta-analysis sought to determine the strength of evidence for the effects of hydration (sodium bicarbonate [SB] and normal saline [NS]), supplementations ( N-acetylcysteine [NAC] and vitamin C), and some common drugs (adenosine antagonists [AAs], statins, loop diuretics, and angiotensin-converting enzyme inhibitors [ACEIs]) on the incidence of contrast-induced nephropathy (CIN) and requirement for hemodialysis after coronary angiography. After screening, a total of 125 trials that reported outcomes were identified. Pooled analysis indicated beneficial effects of SB versus NS (odds ratio [OR] = 0.73; 95% confidence interval [CI]: 0.56-0.94; P = .01), NAC (OR = 0.79; 95% CI: 0.70-0.88; P = .001), vitamin C (OR = 0.64; 95% CI: 0.45-0.89; P = .01), statins (OR = 0.45; 95% CI: 0.35-0.57; P = .001), AA (OR = 0.28; 95% CI: 0.14-0.47; P = .001), loop diuretics (OR = 0.97; 95% CI: 0.33-2.85; P = .9), and ACEI (OR = 1.06; 95% CI: 0.69-1.61; P = .8). Overall, hydration with SB, use of supplements, such as NAC and vitamin C, and administration of statins and AA should always be considered for the prevention of CIN after coronary angiography.

Intravenous magnesium sulfate: new method in prevention of contrast-induced nephropathy in primary percutaneous coronary intervention

BACKGROUND

Contrast-induced acute kidney injury (CI-AKI) is an adverse consequence of percutaneous coronary interventions which results in significant morbidity and mortality and adds to the costs of diagnostic and interventional cardiology procedures. Various pathophysiological mechanisms have been proposed for CI-AKI and various agents tested for its prevention. There is currently a general agreement that adequate pre-procedural hydration constitutes the cornerstone of prevention, yet there are reports of the use of some other agents with various efficacies. We prospectively tested IV magnesium sulfate (Mg) for CI-AKI prevention.

METHOD AND DESIGN

This study is a prospective, randomized, open-labeled, single-center clinical trial. We randomly assigned 122 consecutive patients to two groups. The first group was the control group with routine treatment (n = 64), and second group was the study group with routine treatment plus IV magnesium sulfate 1 g just before the procedure (n = 62). Serum creatinine was measured before the procedure and 2 days after the procedure. The primary end point was the occurrence of CI-AKI within 48 h. CI-AKI was defined as 0.5 mg/dl or more increase in serum creatinine or 25% or more increase above baseline serum creatinine. There was no difference in definition if both of these parameters were present.

RESULTS

The control and study groups were comparable in the overall predicted risk of CI-AKI. Also, the type and volume of the contrast were not significantly different between the two groups. Following angioplasty, CI-AKI occurred in 17 (26.6%) patients in the control group and nine (14.5%) patients in the study group; there was a significant reduction in CI-AKI in the study group (P = 0.01). Additionally, there was no mortality or a need for hemodialysis in either group.

CONCLUSION

In primary PCI patients, the prophylactic use of intravenous Mg can be recommended to be added to traditional hydration for CI-AKI prevention.

Pharmacologic Prophylaxis for Contrast-Induced Acute Kidney Injury

In the effort to prevent contrast-induced acute kidney injury (CI-AKI), several pharmacologic agents have been tested for their single or combined nephroprotective properties. To date, however, no drug has been officially approved for this aim. This article focuses on the three agents that have been most extensively studied: statins, N-acetylcysteine, and ascorbic acid. Particular attention is paid to the impact of these drugs on the CI-AKI prevention and improved prognosis.

Pharmacological strategies to prevent contrast-induced acute kidney injury

Contrast-induced acute kidney injury (CI-AKI) is the most common iatrogenic cause of acute kidney injury after intravenous contrast media administration. In general, the incidence of CI-AKI is low in patients with normal renal function. However, the rate is remarkably elevated in patients with preexisting chronic kidney disease, diabetes mellitus, old age, high volume of contrast agent, congestive heart failure, hypotension, anemia, use of nephrotoxic drug, and volume depletion. Consequently, CI-AKI particularly in high risk patients contributes to extended hospitalizations and increases long-term morbidity and mortality. The pathogenesis of CI-AKI involves at least three mechanisms; contrast agents induce renal vasoconstriction, increase of oxygen free radicals through oxidative stress, and direct tubular toxicity. Several strategies to prevent CI-AKI have been evaluated in experimental studies and clinical trials. At present, intravascular volume expansion with either isotonic saline or sodium bicarbonate solutions has provided more consistent positive results and was recommended in the prevention of CI-AKI. However, the proportion of patients with risk still develops CI-AKI. This review critically evaluated the current evidence for pharmacological strategies to prevent CI-AKI in patients with a risk of developing CI-AKI.

Contrast media induced nephropathy: a literature review of the available evidence and recommendations for practice

BACKGROUND

Contrast media induced nephropathy (CIN) is a sudden compromise of renal function 24-48 h after administering contrast medium during a CT scan or angiography. CIN accounts for 10% of hospital acquired renal failure and is ranked the third cause of acquiring this condition. Identifying patients at risk through proper screening can reduce the occurrence of this condition.

PURPOSE

This review paper aims to critique current evidence, provide a better understanding of CIN, inform nursing practice and make recommendations for bedside nurses and future research.

METHOD

An integrative review of the literature was made using the key terms: "contrast media", "nephritis", "nephropathy", "contrast media induced nephropathy scores", "acute kidney failure", "acute renal failure" and "acute kidney injury". MeSH key terms used in some databases were: "prevention and control", "acute kidney failure" and "treatment". Databases searched included Medline, CINAHL and Academic Search Complete, and references of relevant articles were also assessed. The search included all articles between the years 2000 and 2013.

RESULTS

Sixty-seven articles were obtained as a result of the search, including RCTs, systematic reviews, and retrospective studies.

CONCLUSION

Contrast media induced nephropathy is an iatrogenic complication occurring secondary to diagnostic or therapeutic procedures. At times it is unavoidable but a systematic method of risk assessment should be adopted to identify high risk patients for tailored and targeted approaches to management interventions.

CLINICAL IMPLICATIONS

As the use of contrast media is increasing for diagnostic purposes, it is important that nurses be aware of the risk factors for CIN, identify and monitor high risk patients to prevent deterioration in renal function when possible.

Prevention of contrast-induced AKI: a review of published trials and the design of the prevention of serious adverse events following angiography (PRESERVE) trial

Contrast-induced AKI (CI-AKI) is a common condition associated with serious, adverse outcomes. CI-AKI may be preventable because its risk factors are well characterized and the timing of renal insult is commonly known in advance. Intravenous (IV) fluids and N-acetylcysteine (NAC) are two of the most widely studied preventive measures for CI-AKI. Despite a multitude of clinical trials and meta-analyses, the most effective type of IV fluid (sodium bicarbonate versus sodium chloride) and the benefit of NAC remain unclear. Careful review of published trials of these interventions reveals design limitations that contributed to their inconclusive findings. Such design limitations include the enrollment of small numbers of patients, increasing the risk for type I and type II statistical errors; the use of surrogate primary endpoints defined by small increments in serum creatinine, which are associated with, but not necessarily causally related to serious, adverse, patient-centered outcomes; and the inclusion of low-risk patients with intact baseline kidney function, yielding low event rates and reduced generalizability to a higher-risk population. The Prevention of Serious Adverse Events following Angiography (PRESERVE) trial is a randomized, double-blind, multicenter trial that will enroll 8680 high-risk patients undergoing coronary or noncoronary angiography to compare the effectiveness of IV isotonic sodium bicarbonate versus IV isotonic sodium chloride and oral NAC versus oral placebo for the prevention of serious, adverse outcomes associated with CI-AKI. This article discusses key methodological issues of past trials investigating IV fluids and NAC and how they informed the design of the PRESERVE trial.

Efficacy of pentoxifylline in prevention of contrast-induced nephropathy in angioplasty patients

BACKGROUND

Contrast-induced nephropathy (CIN) is an adverse consequence of contrast media use that results in significant morbidity and mortality and adds significant costs to diagnostic and interventional cardiology procedures. Various pathophysiological mechanisms have been proposed for CIN and various agents have been tested for its prevention. There is currently a general agreement that adequate pre-procedure hydration constitutes the cornerstone of prevention, yet there are reports of the use of some other agents with various efficacies. We prospectively tested pentoxifylline (PTX), an antioxidant, anti-inflammatory drug, for CIN prevention in patients undergoing coronary angioplasty.

MATERIALS AND METHODS

In this prospective, randomized, single-blind, single-center clinical trial, 286 consecutive patients were randomly assigned to the control group (n = 146), with routine treatment and no PTX, or the study group (n = 140), with routine treatment and PTX, 400 mg/tid from 24 h before to 24 h after coronary angioplasty. Serum creatinine was measured before and 2 days after the procedure. The primary end point was the occurrence of CIN within 48 h.

RESULTS

The control and PTX groups were comparable in the overall predicted risk of CIN. Also, the type and volume of the contrast agent were not significantly different between the two groups. Following angioplasty, CIN occurred in 20 (13.69%) patients in the control group and in 12 (8.5%) patients in the study group; the difference was not statistically significant (P = 0.17). Additionally, there was no mortality and need for hemodialysis in either group.

CONCLUSION

In angioplasty patients, the prophylactic oral use of PTX could be recommended for CIN prevention, although no statistically significant protective effect was documented.

How to reduce the incidence of contrast induced acute kidney injury after cardiac invasive procedures, a review and practical recommendations

BACKGROUND

Contrast induced acute kidney injury is an important complication after cardiac (invasive) procedures and is associated with substantial morbidity and mortality. The aim of the current article is to provide a comprehensive overview of the current knowledge regarding contrast induced acute kidney injury.

METHODS

Current literature was reviewed and relevant articles were selected. Articles were identified through MEDLINE and Pubmed selecting articles, limited between 1980 and 2010.

RESULTS

The pathophysiological process resulting in contrast induced acute kidney injury is not completely understood, nevertheless several mechanisms involved have been proposed. However, the risk factors for contrast induced acute kidney injury and its timing are well known, making it amenable for preventive strategies. In the past decade various preventive strategies have been investigated with different results.

CONCLUSIONS

Currently, only adequate hydration, with saline, is uniformly accepted as a beneficial prophylactic strategy. Furthermore promising results have also been reported for several other prophylactic strategies. These results, however, need to be confirmed in future trials.

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.

Strategies for the prevention of contrast-induced acute kidney injury

PURPOSE OF REVIEW

The intravascular administration of iodinated contrast media for diagnostic imaging is a common cause of acute kidney injury and a leading cause of iatrogenic renal disease. The purpose of this review is to describe the principal risk factors for contrast-induced acute kidney injury and to summarize recent data describing the efficacy of various preventive interventions for this condition.

RECENT FINDINGS

Whereas earlier studies suggested that certain low-osmolal contrast agents including iohexol and ioxaglate are more nephrotoxic than iso-osmolal iodixanol, recent clinical trials and meta-analyses comparing other low-osmolal contrast agents with iodixanol have found little difference in risk. The provision of prophylactic renal replacement therapy does not ameliorate the risk of contrast-induced acute kidney injury, and likely poses undue risk. Despite some research supporting a benefit of atrial natriuretic peptide, statins, and prostaglandin analogs, additional data from large, adequately powered studies are needed before these agents can be recommended. N-Acetylcysteine and isotonic intravenous bicarbonate have been investigated intensely, yet the data on these interventions are conflicting due to methodological limitations in past studies.

SUMMARY

Prevention of contrast-induced acute kidney injury involves the identification of high-risk patients, consideration of alternative imaging procedures that do not involve the administration of iodinated contrast, and integration of the cumulative data available on preventive interventions in high-risk patients.

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.

Risk of nephropathy is not increased by the administration of larger volume of contrast during coronary angiography

It is proposed that contrast-induced nephropathy (CN) correlates with the use of increasing contrast volumes during coronary angiography. This supposition has led to the current recommendation to limit the dose of contrast in patients at high risk for renal dysfunction. Limits in contrast dosing may negatively impact the evaluation of patients undergoing cardiac catheterization for myocardial infarction and acute coronary syndrome. The objective of this study was to empirically assess, in a large population, the presence and strength of this correlation. Baseline blood samples and clinical information were obtained from 5256 consenting patients hospitalized for coronary angiography. Levels of serum creatinine were measured pre- and postcatheterization, and the total change in serum creatinine was calculated. Nephropathy was defined as a change of > or =0.5 mg/dL. The total volume of contrast dye (iopamidol, nonionic) used during the angiography procedure was recorded. Logistic regression was used for the primary analysis.The average age was 64 +/- 14 years, and 67% of patients were male. Paradoxically, the incidence of CN was inversely related to the volume in the overall population: 16%, 14%, 8%, and 7% for quartile (Q) 1 (<115 mL), Q2 (115-160 mL), Q3 (161-225 mL), and Q4 (>225 mL) of contrast, respectively (P-trend <0.001). In multivariable regression, this trend toward lower CN remained (Q1 (referent) OR = 1.0, Q2: 1.02, Q3: 0.60, Q4: 0.53, P < 0.001). Other predictors included age, left ventricular ejection fraction, diabetes, and baseline creatinine level (all P < 0.001). For patients at high risk, with a baseline creatinine >2.0 mg/dL (n = 415), contrast volume (Q1: <75 mL, Q2: 75-120 mL, Q3: 121-170 mL, Q4: >170 mL) did not predict either increased or decreased risk of CN (48%, 42%, 49%, 43%, respectively, P-trend = 0.76). This lack of predictive value remained after multivariable adjustment.In this large population, no association was found between the amount of contrast used during angiography and the incidence of CN in patients at initial high risk. The apparent inverse relation of risk with volume in the overall population is likely explained by clinical practice bias. If confirmed, these results may have important clinical implications.

Contrast-induced acute kidney injury in patients with renal dysfunction undergoing a coronary procedure and receiving non-ionic low-osmolar versus iso-osmolar contrast media

BACKGROUND

Although the superiority of low-osmolar over high-osmolar contrast agents in prevention of contrast-induced acute kidney injury (CI-AKI) is generally accepted, the relative nephrotoxicity of iso-osmolar over low-osmolar agents has not yet clearly defined. We examined the incidence of CI-AKI according to the type of contrast agent used in a randomized study of ascorbic acid for CI-AKI prevention.

METHODS

A total of 222 patients with baseline serum creatinine >or=1.2 mg/dL who were undergoing a coronary procedure and who were randomized to receive ascorbic acid or placebo were evaluated. The iso-osmolar agent iodixanol was used in 144 patients, whereas low-osmolar non-ionic agents were used in 78 patients (iomeprol, n = 40; iobitridol, n = 30; iopentol, n = 8). CI-AKI was defined by an absolute serum creatinine increase of >or=0.5 mg/dL or a relative increase of >or=25% measured 2 to 5 days after the procedure.

RESULTS

The groups of patients who received iso-osmolar and low-osmolar non-ionic agents were well balanced in terms of demographic, clinical, and procedural characteristics. The overall CI-AKI incidence was 14.6% for the iso-osmolar iodixanol versus 14.1% for the combined low-osmolar non-ionic agents (iomeprol, 10%; iobitridol, 10%; iopentol, 50%). For iodixanol, the incidence of CI-AKI was 7.4% for patients randomized to receive ascorbic acid and 21.6% for placebo (P = 0.02). The corresponding incidences for the low-osmolar non-ionic agents were 9.1% and 20.6%, respectively (P = 0.19).

CONCLUSION

No differences in CI-AKI incidence were apparent among patients receiving non-ionic iso-osmolar iodixanol and non-ionic low-osmolar contrast agents. The preventative effect of ascorbic acid was also similar.

Interventional procedures: best practice to avoid complications

Technological advances have allowed treatment of patients using interventional radiological imaging including the performance of multiple procedures in almost any vessel, eg, angioplasty, stenting, embolization, and coilings. Patients undergoing any procedure are at risk for complications because of contrast media, radiation exposure, vessel injury, and prolonged time in one position during the procedure. Diagnostic-only procedures minimize use of contrast medium and radiation time, and generally take about one hour to complete. On the other hand, interventional procedures can take several hours and require larger volumes of contrast medium and radiation, as well as increased time lying supine on a procedure table. This article will discuss several potential and known risks associated with interventional procedures, how to monitor for these risks, and evidence-based measures to prevent or minimize their occurrence.

Risk Factors and Therapy Strategies for Contrast-Induced Nephropathy

Contrast-induced nephropathy (CIN) is associated with increased morbidity and mortality, as well as increased costs for medical care, particularly in patients with diabetes mellitus and chronic renal failure. A key step to safer CIN is to identify patients at risk and applying proven preventive interventions. Extracellular volume expansion, minimizing the dose of contrast media, using low-osmolar non-ionic contrast media, stopping the intake of nephrotoxic drugs, and avoiding short intervals between procedures have all been shown to be effective in reducing CIN. The aim of the present review is to summarize the knowledge about the risk factors and prophylactic treatments of CIN.

Reactive Oxygen Species Independent Cytotoxicity Induced by Radiocontrast Agents in Tubular Cells (LLC-PK1 and MDCK)

PURPOSE

Radiocontrast agents (RAs) cause renal tubular damage by hemodynamic imbalance, which could cause hypoxic stimulus and direct cytotoxicity. However, reactive oxygen species (ROS) could be an important factor in RAs' direct cytotoxicity. This study investigated the involvement of ROS in deleterious effects produced by RAs on normoxic and hypoxic renal tubular cells.

MATERIALS AND METHODS

LLC-PK1 and MDCK were exposed to diatrizoate and ioxaglate in normoxic and hypoxic conditions. Apoptotic and necrotic cell death were assessed by acridine orange/ethidium bromide and annexin V methods. Hydrogen peroxide, superoxide anion, and malondialdehyde levels were analyzed by, respectively, 2',7'-dichlorofluorescein, luminal, and thiobarbituric acid. Antioxidant agents were used to prevent cellular RAs damage.

RESULTS

Diatrizoate and ioxaglate decreased cellular viability in both cells, and this effect was enhanced by hypoxic conditions. Diatrizoate induced more injury than ioxaglate to both cell lines. LLC-PK1 underwent necrosis, while MDCK cells underwent apoptosis when exposed to diatrizoate. These results could not be attributed to an increase in osmolality. RAs did not increase hydrogen peroxide, superoxide anion or malondialdehyde levels in both cells. Additionally, N-acetyl-L-cysteine (NAC), ascorbic acid, alpha-tocopherol, glutathione, beta-carotene, allopurinol, cimetidine, and citric acid did not protect cells against RAs damage. Surprising, NAC increased the cellular damage induced by ioxaglate in the both cell lines.

CONCLUSION

The present study shows that RAs induce damage in cultured tubular cells, especially in hypoxic conditions. ROS were not involved in the observed RAs' cytotoxicity, and NAC increased ioxaglate-induced tubular damage.

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

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.

Effects of Acetylcysteine and Probucol on Contrast Medium-induced Depression of Intrinsic Renal Glutathione Peroxidase Activity in Diabetic Rats

BACKGROUND

Antioxidants such as N-acetylcysteine and probucol have been used to protect patients from contrast media-induced nephrotoxicity. The mechanisms underlying these protective effects are not well understood. We hypothesized that acetylcysteine and probucol alter the activity of endogenous antioxidant enzyme activity.

METHODS

Four weeks after induction of diabetes with streptozotocin, diabetic and nondiabetic rats were divided into three groups. Group 1 rats did not receive any antioxidant agents. Group 2 rats were treated with acetylcysteine and group 3 rats with probucol for 1 week before injection of the contrast medium diatrizoate (DTZ).

RESULTS

We found that diabetic rats had higher renal glutathione peroxidase (GPx) activity than normal rats. DTZ suppressed renal GPx activity significantly in both group 1 diabetic and normal rats. Interestingly, renal GPx activity in both diabetic and normal rats pretreated with acetylcysteine or probucol was not inhibited by DTZ. Renal superoxide dismutase (SOD) increased significantly in normal rats after DTZ injection, but not in diabetic rats. Finally, acetylcysteine or probucol did not significantly influence renal SOD.

CONCLUSIONS

These findings suggest that the renal protective effects of acetylcysteine and probucol against contrast-induced oxidative stress and nephrotoxicity may be mediated by altering endogenous GPx activity.

N-acetylcysteine in the prevention of contrast-induced nephropathy: publication bias perpetuated by meta-analyses

BACKGROUND

The use of N-acetylcysteine for the prevention of contrast-induced nephropathy has been the subject of numerous clinical trials and meta-analyses. We sought to examine the possibility of a publication bias and whether meta-analyses have magnified any potential publication bias.

METHODS

We performed a Medline search and a manual search to identify published manuscripts. We also manually searched contemporaneous major cardiology scientific meetings to identify abstracts. We included only randomized controlled clinical trials. We pooled the results of abstracts and manuscripts separately and combined, calculating an odds ratio (OR). We analyzed meta-analyses according to the proportions of manuscripts and abstracts that they included and compared their calculated ORs to the OR of all available contemporaneous data. Our analysis spanned the time from the publication of the first manuscript on this topic through June 2006.

RESULTS

Throughout the study period, the published manuscripts presented a treatment-effect estimate that was more optimistic than that found in unpublished abstracts. There was a temporal trend in that the estimate of treatment effect was greatest with early publications, which diminished as additional data became available. The profile of the journal (as assessed by impact factor) in which a manuscript was published was not related to the quality of the manuscript. However, studies reaching a positive conclusion were published in journals with higher impact factors compared with studies reaching negative conclusions. Meta-analyses included a substantially greater proportion of published manuscripts versus unpublished abstracts and provided more optimistic assessments of treatment effect than would have been derived had all available data been assessed.

CONCLUSIONS

There was a significant publication bias that persisted throughout the life cycle of this clinical question. The bias was further amplified by meta-analyses.

Interactions between serum creatinine, volume status, N-acetylcysteine, and contrast-induced nephropathy

Contrast-induced nephropathy is reported to be the third leading cause of acute renal failure. The development of contrast-induced nephropathy is associated with prolonged hospitalization, the potential need for renal replacement therapy, and increased mortality. N-acetylcysteine is commonly used for the prevention of contrast-induced nephropathy despite inconsistent results from numerous clinical trials and meta-analyses. The advantage of N-acetylcysteine in most studies was based on a decrease in the serum creatinine concentration and a decrease in oxidative stress. N-acetylcysteine itself can directly lower serum creatinine concentration without improving renal function, and hypovolemia can affect the oxidative stress. In most of the N-acetylcysteine studies, there are a lack of volume status and secondary end points. The value of N-acetylcysteine for the prevention of contrast-induced nephropathy seems questionable. The interactions between serum creatinine, N-Acetylcysteine, volume status, and the development of contrast-induced nephropathy were discussed in this letter.

Low incidence of nephropathy in surgical ICU patients receiving intravenous contrast: a retrospective analysis

OBJECTIVE

Various studies have documented a markedly high incidence of contrast-induced nephropathy (CIN). Most of these studies were conducted in patients not in the ICU. In ICU patients intravenous contrast may be withheld for fear of CIN. We investigated the incidence of CIN in ICU patients.

DESIGN AND SETTING

Retrospective cohort study in a 12-bed tertiary surgical ICU.

PATIENTS

Were evaluated all contrast-enhanced abdominal computed tomography (CT) scans between 1995 and 2003 in patients not on renal replacement therapy (RRT) before the CT. Patients received prophylactic prehydration and, since 2000, acetylcysteine. Low-osmolarity, nonionic contrast was used. CIN was defined as an increase in serum creatinine of more than 44 micromol/l (0.5 mg/dl) within 48 h after contrast administration, with no increase in creatinine of 44 micromol/l during the preceding 2 days. RRT initiated after the CT was also recorded.

MEASUREMENTS AND RESULTS

The patient was not on RRT before CT in 486 of 589 cases (16% diabetics). In these 486 cases the median (IQR) creatinine decreased significantly from 88 micromol/l (66-124) on the day of the CT-scan to 84 micromol/l (63-118) 2 days later. Only 7 of the 486 cases (1.4%) fulfilled the criteria of CIN, and in another 17 (3.5%) RRT was started after the CT. Important coexisting causes of renal failure were present in these patients, and in all survivors renal function recovered.

CONCLUSIONS

CT with modern contrast is associated with a very low incidence of nephropathy in predominantly nondiabetic surgical ICU patients. Intravenous contrast should only rarely be withheld in these patients.

Adequate range for sulfur-containing amino acids and biomarkers for their excess: lessons from enteral and parenteral nutrition

The adequacy range of dietary requirements of specific amino acids in disease states is difficult to determine. In health, several techniques are available allowing rather precise quantification of requirements based on growth of the organism, rises in plasma concentration, or increases in the oxidation of marker amino acids during incremental administration of the amino acid under study. Requirements may not be similar in disease with regard to protein synthesis or with regard to specific functions such as scavenging of reactive oxygen species by compounds including glutathione. Requirements for this purpose can be assessed only when such a function can be measured and related to clinical outcome. There is apparent consensus concerning normal sulfur amino acid (SAA) requirements. WHO recommendations amount to 13 mg/kg per 24 h in healthy adults. This amount is roughly doubled in artificial nutrition regimens. In disease or after trauma, requirements may be altered for methionine, cysteine, and taurine. Although in specific cases of congenital enzyme deficiency, prematurity, or diminished liver function, hypermethionemia or hyperhomocysteinemia may occur, SAA supplementation can be considered safe in amounts exceeding 2-3 times the minimal recommended daily intake. Apart from some very specific indications (e.g., acetaminophen poisoning), the usefulness of SAA supplementation is not yet established. There is a growing body of data pointing out the potential importance of oxidative stress and resulting changes in redox state in numerous diseases including sepsis, chronic inflammation, cancer, AIDS/HIV, and aging. These observations warrant continued attention for the potential role of SAA supplementation. In particular, N-acetylcysteine remains promising for these conditions.

Risk factors for contrast-induced nephropathy

An increasing number of diagnostic imaging and interventional procedures require the use of radiographic contrast agents which has led to a parallel increase in the incidence of contrast-induced nephropathy (CIN). CIN is a serious clinical problem associated with increased morbidity and mortality, particularly in patients with chronic renal failure (see the Case Report). A key step to minimize CIN is to identify patients at risk of CIN. The aim of the present review was to summarize the knowledge about the risk factors of CIN, including the review of ultimate clinical research and developments.

Strategies to reduce the risk of contrast nephropathy: an evidence-based approach

PURPOSE OF REVIEW

Contrast nephropathy is a common complication associated with angiographic procedures that carries significant morbidity and mortality. Recent clinical trials of prophylactic strategies have reported contradictory results. This review presents recent insights into the pathophysiology of contrast nephropathy and reviews trial results in this context.

RECENT FINDINGS

A prediction rule has been developed to better identify patients at risk of developing contrast nephropathy. Factors other than osmolality play a significant role in the pathogenesis of contrast nephropathy, at least for agents with osmolalities of 800 mOsm/kg or less. New randomized trial data do not support a role for N-acetylcysteine in contrast nephropathy prophylaxis and there is additional evidence that fenoldopam is ineffective. Pooled analyses of theophylline prophylaxis trials are inconclusive. Theoretical and clinical data suggest that ascorbic acid may be renoprotective, but this requires further study.

SUMMARY

The overall incidence of contrast nephropathy remains low. Available evidence supports the use of hydration and low volumes of iso-osmolar or low-osmolar contrast in patients at risk of developing contrast nephropathy. Heterogeneity has affected interpretability of interventional trials of N-acetylcysteine or theophylline prophylaxis strategies. Future clinical trials must identify and target moderate-risk to high-risk patients and ensure that proven therapies are included in trial protocols.

Hyperuricemia as a risk factor for contrast-induced nephropathy in patients with chronic kidney disease

OBJECTIVES

Hyperuricemia as a risk factor for contrast-induced nephropathy (CIN) has not been studied.

BACKGROUND

The aim of the present study was to assess the influence of hyperuricemia on the development of CIN in patients undergoing coronary angiography.

METHODS

This was a prospective cohort study. A total of 266 patients with a mean age of 58.33 +/- 7.85 years and serum creatinine > or = 1.2 mg/dl were divided into two groups (hyperuricemic, n = 126, and normouricemic, n = 140). CIN was defined as an increase of > or = 25% in creatinine over baseline within 48 hr of angiography, and hyperuricemia as serum uric acid > or = 7 mg/dl in males and > or = 6.5 mg/dl in females.

RESULTS

CIN occurred in 15.1% of the hyperuricemic group and 2.9% of the normouricemic group (P < 0.001). Serum creatinine increased from 1.45 +/- 0.20 to 1.67 +/- 0.45 mg/dl in the hyperuricemic group and from 1.42 +/- 0.16 to 1.56 +/- 0.23 mg/dl in the normouricemic group (P < 0.001). Hyperuricemia [odds ratio (OR) 4.71; 95% confidence interval (95% CI) 1.29-17.21; P = 0.019] and a high incidence of multi-vessel coronary involvement (OR 3.59; 95% CI 1.12-11.48; P = 0.032) in the hyperuricemic group were predictors of CIN. Hypoalbuminemia (P = 0.001) and age > or = 70 years (P = 0.023) were other risk indicators of CIN. Length of hospital stay (P < 0.001) and CIN requiring renal replacement therapy (P = 0.017) were significantly higher in hyperuricemic group. Serum uric acid level > or = 7 mg/dl in males and > or = 5.9 mg/dl in females were found to be the best cut-off value for prediction of CIN.

CONCLUSION

Our data support the hypothesis that patients with hyperuricemia are at risk of developing CIN.

Contrast nephropathy may be partly mediated by autonomic dysfunction: renal failure considered as a modern maladaptation of the prehistoric trauma response

The mechanism behind iodinated radiocontrast nephropathy remains elusive. Direct oxidative damage is the prevailing hypothesis, but the apparent protective effect of iodine against oxidation contradicts this view. We propose that autonomic dysfunction participates in the pathogenesis of radiocontrast nephropathy and may account for other contrast-associated reactions previously attributed to allergy. Iodine, through its effects on thyroid function and chemoreceptor response to metabolic acidosis, may induce hyperadrenergia and consequently diminish renovascular flow and urine output. The renal response to adrenergia likely served an adaptive function during prehistoric evolution when trauma was a dominant source of hypovolemia and adrenergia, but the response may behave maladaptively today as evolutionarily nai ve triggers for adrenergia have emerged. Autonomic dysfunction can further impair renal function by deranging renovascular autoregulation and inducing oxidative reperfusion injury as a secondary phenomenon. Many other causes of acute renal failure such as drug toxicity, surgery, hospitalization, and diabetes may operate through hyperadrenergia, impaired renovascular autoregulation, and oxidative reperfusion injury. Dialysis, a volume reduction therapy for renal failure, can counterintuitively worsen renal dysfunction by exacerbating adrenergia, which may explain its association with accelerated atherosclerosis, inflammation, and cancer. Other examples of vicious cycles that perpetuate renal dysfunction may include renal artery stenosis, carotid stenosis, and atherosclerosis as well as the cardio-renal, hepato-renal, and pulmonary-renal syndromes. The benefits of hydration and bicarbonate in protecting renal function may operate in part through baroreceptor- and chemoreceptor-mediated reduction of sympathovagal ratio, respectively. New treatment paradigms for renal failure including pharmacologic and electro-mechanical therapies are envisioned based on autonomic remodeling, reduced sympathovagal ratio, and neuromodulation of pathways typically associated with trauma such as renin, angiotensin, vasopressin, and aldosterone.

A Clinical and Pharmacoeconomic Justification for Intravenous Acetylcysteine

Paracetamol (acetaminophen) poisoning remains the most common exposure reported to US poison information centres and the leading cause of poisoning-related fatalities, despite the availability of an effective antidote, acetylcysteine. Oral acetylcysteine solution has been approved for the management of acetaminophen poisoning in the US for four decades. Until the recent approval of intravenous acetylcysteine in the US, it was necessary to compound the oral solution for intravenous administration. The effectiveness and tolerability of oral and intravenous acetylcysteine for the prevention of hepatotoxicity induced by paracetamol poisoning are well established in the literature. Intravenous acetylcysteine may be preferred over oral administration based on improved tolerability, ease of administration and the shortened course of therapy (20 hours intravenous vs 72 hours oral). The two intravenous acetylcysteine regimens documented in the literature, 48 hours and 20 hours, have similar efficacy when started within 8-10 hours of ingestion. Although there are no legal concerns with continuing the routine compounding of the oral solution to an intravenous product, new standards for pharmacy compounding of sterile preparations set forth by the US Pharmacopoeia highlight that the risk of compounding products for intravenous use must be assessed carefully. Changing the route of administration of a sterile oral solution to an intravenous preparation, when a commercial sterile and pyrogen-free product is available, may not be advisable. The best cost-containment strategies must be used for introduction of the more costly sterile, pyrogen-free intravenous acetylcysteine formulation by hospitals and healthcare systems. The intravenous acetylcysteine product is more cost effective when given for 20 hours than other treatment protocols based on the costs of acetylcysteine and hospitalisation. If used per protocol, the 20-hour intravenous acetylcysteine regimen may decrease hospital length of stay, thereby, offsetting the increased drug cost. Data conflict on the efficacy and administration of intravenous acetylcysteine for off-label uses, such as radiographic contrast media-induced nephropathy prevention and reperfusion in orthotopic liver transplantation. The costs for the intravenous formulation for these indications is significantly higher than use of the oral formulation for oral administration in radiographic contrast media-induced nephropathy prevention and compounded for intravenous use in orthotopic liver transplantation. The oral solution should be retained by healthcare systems for oral and inhalation applications, such as respiratory conditions, oral administration for radiographic contrast media nephropathy prevention, or the use of the 72-hour oral protocol to treat paracetamol poisoning, when the intravenous preparation cannot be used.