Sodium bicarbonate for the prevention of contrast-induced nephropathy: a meta-analysis of 17 randomized trials

Radiographic Contrast Media and the Kidney

AKI is a potential complication of intravascular iodinated contrast exposure. Contrast-associated AKI, which typically manifests as small and transient decrements in kidney function that develop within several days of contrast administration, is associated with serious adverse outcomes, including progressive kidney dysfunction and death. However, a causal link between the small increases in serum creatinine that characteristically occur with contrast-associated AKI and serious adverse outcomes remains unproven. This is important given mounting evidence that clinically indicated, potentially lifesaving radiographic procedures are underutilized in patients with CKD. This has been hypothesized to be related to provider concern about precipitating contrast-associated AKI. Intravascular gadolinium-based contrast, an alternative to iodinated contrast that is administered with magnetic resonance imaging, has also been linked with potential serious adverse events, notably the development of nephrogenic systemic fibrosis in patients with severe impairment in kidney function. Patients hospitalized in the intensive care unit frequently have clinical indications for diagnostic and therapeutic procedures that involve the intravascular administration of contrast media. Accordingly, critical care providers and others treating critically ill patients should possess a sound understanding of the risk factors for and incidence of such outcomes, the ability to perform evidence-based risk-benefit assessments regarding intravascular contrast administration, and knowledge of empirical data on the prevention of these iatrogenic complications.

Serum osmolarity as a potential predictor for contrast-induced nephropathy following elective coronary angiography

BACKGROUND AND OBJECTIVES

Contrast-induced nephropathy (CIN) is a relatively common complication following primary coronary angiography (CAG) or percutaneous coronary intervention (PCI), especially in at-risk patients. The goal of this study is to evaluate the role of pre-procedural serum osmolarity as a risk factor for CIN in patients undergoing elective CAG for stable coronary artery disease (CAD).

MATERIALS AND METHODS

A total of 356 stable CAD patients scheduled to undergo CAG or PCI were included in this two-center study. Serum osmolarity was calculated on admission. CIN was defined according to the KDIGO criteria.

RESULTS

There were 45 (12.6%) patients who developed CIN 48-72 h after CAG or PCI. CIN patients had a higher prevalence of diabetes (51.1% in those with CIN vs 24.4% in those without CIN, p < 0.001), higher serum glucose (129 mg/dL in those with CIN vs 108 mg/dL in those without CIN, p < 0.001), blood urea nitrogen (22.4 mg/dL in those with CIN vs 19.0 mg/dL in those without CIN, p = 0.01) and serum osmolarity (294.2 mOsm in those with CIN vs 290.1 mOsm in those without CIN, p < 0.001) levels, had received a higher dose of contrast (250 mL in those with CIN vs 200 mL in those without CIN, p = 0.03) but had lower hemoglobin (12.9 g/dL in those with CIN vs 13.6 g/dL in those without CIN, p = 0.04) level. In multivariate analysis, serum osmolarity [odds ratio (OR) 1.11; 95% confidence interval (CI) 1.04-1.18 for each mOsm/L increase; p = 0.001], diabetes (OR 2.43, 95% CI 1.26-4.71; p = 0.01), C-reactive protein (OR 1.04, 95% CI 1.01-1.08 for each mg/dL increase; p = 0.02) and contrast volume (OR 34.66, 95% CI 1.25-962.22 for each L increase; p = 0.04) remained as independent predictors of CIN. Serum sodium, glucose and blood urea nitrogen contributed to the excess serum osmolarity of CIN patients.

CONCLUSION

Serum osmolarity is a cheap and widely available marker that can reliably predict CIN after CAG or PCI. Future research should focus on determining a clinically optimal cutoff for serum osmolarity that would warrant preventive interventions. Furthermore, later research may investigate the role of serum osmolarity not only as a risk factor but also as a pathogenetic mechanism underlying CIN.

Can Thrombus Burden Predict Contrast-Induced Nephropathy in Patients With ST-Segment Elevation Myocardial Infarction?

The incidence of contrast-induced nephropathy (CIN) increases in the range from patients with unstable angina to ST-segment elevation myocardial infarction (STEMI). Platelet activation has been associated with pathophysiology of nephropathy and thrombus burden in the infarct-related arteries. We investigated the impact of thrombus burden on CIN in patients with STEMI. We enrolled 883 patients with STEMI who received primary percutaneous coronary intervention. Patients were divided into groups according to thrombus burden and CIN development. Thrombus burden was scored based on thrombolysis in myocardial infarction thrombus grades (TGs). Thrombus grade 4 was defined as large thrombus burden (LTB), while thrombus burden <TG 4 was defined as small thrombus burden. A total of 126 (14.2%) patients with STEMI had CIN, while 313 (35.4%) patients had LTB. Compared to CIN (-) patients, CIN (+) patients were older, had lower hemoglobin levels, lower ejection fraction, and higher contrast media volume administration. Multivariate logistic regression analysis demonstrated that LTB, age, hypertension, and admission glomerular filtration rate were independent predictors of CIN (P = .016, P < .001, P = .028, P < .001, respectively). Thrombus burden, which is measurable during angiography, may be helpful in the determination of CIN risk in patients with STEMI.

Design of Clinical Trials in Acute Kidney Injury: Lessons from the Past and Future Directions

Acute kidney injury (AKI) is a common condition with multiple etiologies and variable clinical findings and pathologic manifestations. AKI is associated with serious adverse clinical outcomes, including the development of de novo chronic kidney disease, accelerated progression of pre-existing chronic kidney disease, end-stage kidney disease, and increased mortality. Past research has advanced our understanding of the pathophysiology, epidemiology, and outcomes of AKI significantly, however, little progress has been made in the development of evidence-based interventions for its prevention and treatment. In this review, we discuss key considerations in the design of clinical trials in AKI and highlight significant methodologic limitations that precluded many past studies from determining the effectiveness of preventive and therapeutic strategies for this common and serious condition.

Uric Acid is a Useful Tool to Predict Contrast-Induced Nephropathy

Developing contrast-induced nephropathy (CIN) after primary percutaneous coronary intervention (pPCI) has a negative impact on survival and morbidity. We assessed the predictive value of serum uric acid (SUA) for the development of CIN in patients with ST-segment elevation myocardial infarction (STEMI) who underwent pPCI. Contrast-induced nephropathy was defined an increase of ≥25% or ≥0.5 mg/dL in creatinine concentrations within 72 hours after pPCI. Patients were divided into 2 groups according to admission median SUA level. Serum uric acid level was <5.4 mg/dL (group 1; n = 222) and ≥5.4 mg/dL (group 2; n = 228). Compared to group 1, development of CIN (12% vs 20%, P < .001) was significantly greater in group 2. Using a cut point of >5.45 mg/dL, the SUA level predicted development of CIN with a sensitivity of 70% and specificity of 67%. In multiple logistic regression analysis, SUA level, diabetes mellitus, left ventricular ejection fraction <50%, contrast volume, estimated glomerular filtration rate, and C-reactive protein level emerged as independent predictors of CIN. In conclusion, elevated SUA is an independent risk factor for the development of CIN after pPCI in patients with STEMI.

How Strong Is the Evidence for Sodium Bicarbonate to Prevent Contrast-Induced Acute Kidney Injury After Coronary Angiography and Percutaneous Coronary Intervention?

Hydration with sodium bicarbonate is one of the strategies to prevent contrast-induced acute kidney injury (CI-AKI). The purpose of this study was to determine how strong is the evidence for sodium bicarbonate to prevent CI-AKI after coronary angiography (CAG) and/or percutaneous coronary intervention (PCI).We conducted PubMed, EMBASE, and CENTRAL databases to search for randomized controlled trials (RCTs) comparing the efficacy of sodium bicarbonate with sodium chloride to prevent CI-AKI after CAG and/or PCI. Relative risk (RR), standardized mean difference (SMD), or weighted mean difference (WMD) with 95% confidence intervals (CIs) was calculated. Heterogeneity, publication bias, and study quality were evaluated, sensitivity analyses, cumulative analyses, and subgroup analyses were performed. The risk of random errors was assessed by trial sequential analysis (TSA).Sixteen RCTs (3537 patients) met the eligibility criteria. Hydration with sodium bicarbonate showed significant beneficial effects in preventing CI-AKI (RR 0.67; 95% CI: 0.47-0.96, P = 0.029), decreasing the change in serum creatinine (SCr) (SMD -0.31 95% CI: -0.55 to -0.07, P = 0.011) and estimated glomerular filtration rate (eGFR) (SMD -0.17 95% CI: -0.30 to -0.04, P = 0.013). But no significant differences were observed in the requirement for dialysis (RR 1.11; 95% CI: 0.60-2.07, P = 0.729), mortality (RR 0.71; 95% CI: 0.41-1.21, P = 0.204) and reducing the length of hospital stay (LHS) (WMD -1.47; 95% CI: -4.14 to 1.20, P = 0.279). The result of TSA on incidence of CI-AKI showed the required information size (RIS = 6614) was not reached and cumulative z curve did not cross TSA boundary. The result of TSA on the requirement for dialysis and mortality demonstrated the required information sizes (RIS = 170,510 and 19,516, respectively) were not reached, and the cumulative z-curve did not cross any boundaries.The evidence that sodium bicarbonate reduces the incidence of CI-AKI is encouraging but more well-designed randomized controlled trails are required to allow definitive firm conclusion to be drawn.

The efficacy of sodium bicarbonate in preventing contrast-induced nephropathy in patients with pre-existing renal insufficiency: a meta-analysis

OBJECTIVE

The aim of this meta-analysis was to explore the efficacy of sodium bicarbonate in preventing contrast-induced nephropathy (CIN).

METHODS

We searched PubMed, Medline and the Cochrane Library from 1 January 2004 to 1 August 2014. The effect estimate was expressed as a pooled OR with 95% CI, using the fixed-effects or random-effects model.

RESULTS

20 randomised controlled trials (n=4280) were identified. Hydration with sodium bicarbonate was associated with a significant decrease in CIN among patients with pre-existing renal insufficiency (OR 0.67, 95% CI 0.47 to 0.96; p=0.027). However, moderate heterogeneity was noted across trials (I(2)=48%; p=0.008). Subgroup analyses indicated a better effect of sodium bicarbonate in studies using low-osmolar (OR 0.59, 95% CI 0.37 to 0.93; p=0.024) compared with iso-osmolar contrast agents (OR 0.76, 95% CI 0.43 to 1.34; p=0.351). The odds of CIN with sodium bicarbonate were lower in studies including only patients undergoing emergency (OR 0.16, 95% CI 0.05 to 0.51; p=0.002) compared with elective procedures (OR 0.76, 95% CI 0.54 to 1.06; p=0.105). Sodium bicarbonate was more beneficial in patients given a bolus injection before procedures (OR 0.15, 95% CI 0.04 to 0.54; p=0.004) compared with continuous infusion (OR 0.75, 95% CI 0.53 to 1.05; p=0.091). Sodium bicarbonate plus N-acetylcysteine (OR 0.17, 95% CI 0.04 to 0.79; p=0.024) was better than sodium bicarbonate alone (OR 0.71, 95% CI 0.48 to 1.03; p=0.071). The effect of sodium bicarbonate was considered greater in papers published before (OR 0.19, 95% CI 0.09 to 0.41; p=0.000) compared with after 2008 (OR 0.85, 95% CI 0.62 to 1.16; p=0.302). However, no significant differences were found in mortality (OR 0.69, 95% CI 0.36 to 1.32; p=0.263) or requirement for dialysis (OR 1.08, 95% CI 0.52 to 2.25; p=0.841).

CONCLUSIONS

Sodium bicarbonate is effective in preventing CIN among patients with pre-existing renal insufficiency. However, it fails to lower the risks of dialysis and mortality and therefore cannot improve the clinical prognosis of patients with CIN.

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.

Contrast-induced Nephropathy

Contrast-induced nephropathy (CIN) is a serious complication of angiographic procedures resulting from the administration of contrast media (CM). It is the third most common cause of hospital acquired acute renal injury and represents about 12% of the cases. CIN is defined as an elevation of serum creatinine (Scr) of more than 25% or ≥0.5 mg/dl (44 μmol/l) from baseline within 48 h. More sensitive markers of renal injury are desired, therefore, several biomarkers of tubular injury are under evaluation. Multiple risk factors may contribute to the development of CIN; these factors are divided into patient- and procedure-related factors. Treatment of CIN is mainly supportive, consisting mainly of careful fluid and electrolyte management, although dialysis may be required in some cases. The available treatment option makes prevention the corner stone of management. This article will review the recent evidence concerning CIN incidence, diagnosis, and prevention strategies as well as its treatment and prognostic implications.

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-induced nephropathy in percutaneous coronary interventions: pathogenesis, risk factors, outcome, prevention and treatment

Contrast-induced nephropathy (CIN) is a well-known adverse event of therapeutic and diagnostic procedures requiring the administration of contrast medium (CM). The lack of a universal CIN definition and glomerular filtration rate markers that vary have resulted in a variety of reported incidences. The development of CIN is associated with an increase in the length of hospital stay and the risk of death. Preexisting renal dysfunction, age, diabetes, congestive heart failure and the volume of CM administered are all associated with a risk for developing CIN. The literature suggests the use of low-osmolarity CM and supports volume supplementation before administration. Moreover, other strategies to avoid CIN, including treatment with N-acetylcysteine and sodium bicarbonate have variable levels of evidence. This review examines the main components of the pathogenesis and risk factors of CIN and possible preventive measures and therapies.

ACE-I/ARB therapy prior to contrast exposure: what should the clinician do?

Contrast-induced nephropathy (CIN) is now one of the three leading causes of acute kidney injury in the world. A lot is known about the risk factors of CIN, yet it remains a major cause of morbidity, end stage renal disease, prolonged hospital stay, and increased costs as well as a high mortality. Many patients undergoing contrast-based radiological investigations are treated with angiotensin converting inhibitors (ACE-Is) or angiotensin receptor blockers (ARBs) for their cardiac and renal benefits and their known mortality benefits. However, controversy exists among clinicians as to whether ACE-Is and ARBs should be continued or discontinued prior to contrast media exposure. In this paper we review the current evidence on ACE-I/ARB therapy for patients undergoing procedures involving use of contrast media and provide recommendations as to whether these drugs should be continued or held prior to contrast exposure.

Impact of mannose-binding lectin deficiency on radiocontrast-induced renal dysfunction

Contrast-induced nephropathy (CIN) is the third leading cause of acute renal failure in hospitalized patients. Endothelial dysfunction, renal medullary ischemia, and tubular toxicity are regarded as the most important factors in the pathogenesis of CIN. Mannose-binding lectin (MBL), a pattern recognition protein of the lectin pathway of complement, has been found to aggravate and mediate tissue damage during experimental renal ischemia/reperfusion (I/R) injury which was alleviated by inhibition with C1 inhibitor, a potent MBL, and lectin pathway inhibitor. In this paper, we highlight the potential role of MBL in the pathogenesis of human CIN. In experimental I/R models, MBL was previously found to induce tubular cell death independent of the complement system. In addition, after binding to vascular endothelial cells, MBL and its associated serine proteases were able to trigger a proinflammatory reaction and contribute to endothelial dysfunction. In humans, urinary MBL was increased after administration of contrast media and in individuals with CIN. Moreover, individuals with normal/high MBL levels were at increased risk to develop radiocontrast-induced renal dysfunction. Hence, MBL and the lectin pathway seem to be a promising target given that a licensed, powerful, human recombinant inhibitor exits to be added to the scarce armamentarium currently available for prophylaxis of CIN.

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.

Contrast-induced acute kidney injury and renal support for acute kidney injury: a KDIGO summary (Part 2)

Acute kidney injury (AKI) is a common and serious problem affecting millions and causing death and disability for many. In 2012, Kidney Disease: Improving Global Outcomes completed the first ever international multidisciplinary clinical practice guideline for AKI. The guideline is based on evidence review and appraisal, and covers AKI definition, risk assessment, evaluation, prevention, and treatment. Two topics, contrast-induced AKI and management of renal replacement therapy, deserve special attention because of the frequency in which they are encountered and the availability of evidence. Recommendations are based on systematic reviews of relevant trials. Appraisal of the quality of the evidence and the strength of recommendations followed the Grading of Recommendations Assessment, Development and Evaluation approach. Limitations of the evidence are discussed and a detailed rationale for each recommendation is provided. This review is an abridged version of the guideline and provides additional rationale and commentary for those recommendation statements that most directly impact the practice of critical care.

How to reduce nephropathy following contrast-enhanced CT: a lesson in policy implementation

In excess of 50 contrast-enhanced computed tomography (CT) examinations are typically undertaken in our tertiary hospital NHS Trust each weekday, approximately 13,000 each year. In the Department of Radiology alone, we inject more than 1300 l of iodinated contrast medium per annum. There is a real need to devise a policy to anticipate contrast medium-induced nephropathy (CIN) and minimize its effects, without disrupting the high-intensity CT service. Having written a comprehensive yet pragmatic policy to reduce the incidence of this iatrogenic condition, it seemed sensible to share it with the wider radiology community and share the experience and lessons learnt in engaging all the stakeholders, ushering in the change with as little fuss as possible. The ramifications on primary and secondary care had to be anticipated, resource implications managed, and staff trained. This review is therefore presented in four sections: framing the problem, assessing its size and nature; a succeeding section on the available guidelines and their uptake; the policy itself to reduce CIN in CT is presented in the third section; and crucially, a description of the policy introduction process in the last section.

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.

Contrast-induced kidney injury: mechanisms, risk factors, and prevention

In general, iodinated contrast media (CM) are tolerated well, and CM use is steadily increasing. Acute kidney injury is the leading life-threatening side effect of CM. Here, we highlight endpoints used to assess CM-induced acute kidney injury (CIAKI), CM types, risk factors, and CIAKI prevention. Moreover, we put forward a unifying theory as to how CIAKI comes about; the kidney medulla's unique hyperosmolar environment concentrates CM in the tubules and vasculature. Highly concentrated CM in the tubules and vessels increases fluid viscosity. Thus, flow through medullary tubules and vessels decreases. Reducing the flow rate will increase the contact time of cytotoxic CM with the tubular epithelial cells and vascular endothelium, and thereby damage cells and generate oxygen radicals. As a result, medullary vasoconstriction takes place, causing hypoxia. Moreover, the glomerular filtration rate declines due to congestion of highly viscous tubular fluid. Effective prevention aims at reducing the medullary concentration of CM, thereby diminishing fluid viscosity. This is achieved by generous hydration using isotonic electrolyte solutions. Even forced diuresis may prove efficient if accompanied by adequate volume supplementation. Limiting the CM dose is the most effective measure to diminish fluid viscosity and to reduce cytotoxic effects.

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.

Contrast-induced acute kidney injury: the at-risk patient and protective measures

Contrast-induced acute kidney injury (CI-AKI) is a major complication following radiocontrast procedures. In this review, we characterize the recent literature on CI-AKI, risk factors, prevention, biomarkers, and new technologies. The premise of CI-AKI prophylaxis should focus on implementing mandatory standing orders before and after cardiac catheterization for hydration with normal saline or sodium bicarbonate and use of high-dose (1200-mg) N-acetylcysteine. Contrast agents may play a role in preventing CI-AKI. Implement catheter-laboratory technology and awareness to limit the amount of contrast dye used for any patient.

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.

The contrast medium volume to estimated glomerular filtration rate ratio as a predictor of contrast-induced nephropathy after primary percutaneous coronary intervention

BACKGROUND

Contrast-induced nephropathy (CIN) is a serious complication in percutaneous coronary intervention (PCI) patients, which may be related to the contrast dose used during cardiac catheterization.

METHODS

We prospectively investigated 277 consecutive consenting patients with acute ST-segment elevation myocardial infarction (STEMI) who were given primary PCI, and we calculated their ratio of volume of contrast media to estimated glomerular filtration rate (V/eGFR). Receiver-operator characteristic methods were used to identify the optimal sensitivity for the observed range of V/eGFR for CIN (i.e., within 48-72 h). The predictive value of V/eGFR for the risk of CIN was assessed using multivariable logistic regression.

RESULTS

Twenty-five (9%) patients developed CIN. The baseline mean and median V/eGFR values were significantly greater among patients with CIN (mean 3.22 ± 1.53, median 2.97, and interquartile range 1.90-4.17) than among those without CIN (mean 1.80 ± 1.00, median 1.52, and interquartile range 1.12-2.21, P < 0.001). The receiver-operator characteristic curve analysis indicated that a V/eGFR ratio of 2.39 was a fair discriminator for CIN (C statistic 0.81). After adjusting for other known predictors of CIN, a V/eGFR ratio ≥ 2.39 remained significantly associated with CIN (odds ratio 4.24, 95% confidence interval 1.23-14.66, P < 0.05).

CONCLUSION

A V/eGFR ratio ≥ 2.39 was a significant and independent predictor of CIN after primary PCI in patients with STEMI.

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.

Update on the diagnosis and management of acute kidney injury

Acute kidney injury (AKI) is an independent risk factor for morbidity and mortality. This review provides essential information for the diagnosis and management of AKI. Blood urea nitrogen and serum creatinine are used for the diagnosis of AKI. The review also focuses on recent studies on the diagnosis of AKI using the RIFLE (R-renal risk, I-injury, F-failure, L-loss of kidney function, E-end stage kidney disease) and Acute Kidney Injury Network criteria, and serum and urine AKI biomarkers. Dialysis is the only Food and Drug Administration-approved therapy for AKI. Recent studies on the dose of dialysis in AKI are reviewed.

Novel aspects of pharmacological therapies for acute renal failure

Acute renal failure (ARF) comprises several syndromes that are associated with a sudden decrease in renal function. ARF is common among critically ill patients, is typically multifactorial and is of great prognostic significance. Indeed, even moderate changes in renal function significantly add to the morbidity and worsen mortality associated with ARF. Recent definitions, namely the renal Risk, Injury, Failure, Loss of renal function and End-stage kidney disease (RIFLE) classification or Acute Kidney Injury Network (AKIN) criteria, which incorporate the levels of oliguria in addition to fractional serum creatinine elevation, are important because the magnitude of kidney injury according to those definitions correlates very well with both short- and long-term patient survival. However, preventive strategies are most effective when started before oliguria or elevated serum creatinine is detectable, as those criteria already reflect established renal tubular cell injury. New biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL), liver-type fatty acid binding protein (L-FABP) or kidney injury molecule-1 (KIM-1) that increase prior to the serum creatinine elevation are promising and have been proven to be useful in this regard in a few clinical trials. In addition, genetic profiling may define patients at risk earlier and help to individualize preventive strategies. Well established strategies include limiting dehydration and hypotension by the use of intravenous isotonic fluids at an optimal and individualized rate, as well as avoiding exposure to nephrotoxins, which include aminoglycosides, amphotericin or non-ionic contrast. Generally accepted and evidence-based pharmacological preventive or therapeutic options have not yet been established, although many drugs (e.g. renal vasodilators, diuretics and HMG-CoA reductase inhibitors [statins]) have been tested. New promising agents interfere with the apoptotic signalling that can occur in the setting of toxin exposure or ischaemia-reperfusion injury, limit inflammatory responses or modulate endothelial cell activation. In the future, these new approaches will enable us to extend our therapeutic repertoire.

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.

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 for the prevention of contrast induced nephropathy: a meta-analysis of published clinical trials

BACKGROUND

Contrast induced nephropathy (CIN) is a serious but rare complication following contrast based procedures. Sodium bicarbonate (NaHCO(3)) has been postulated to prevent CIN by various mechanisms. However, the outcomes following sodium bicarbonate administration to prevent CIN have been inconsistent.

METHODS

A meta-analysis of published randomized clinical trials to determine if the administration of sodium bicarbonate is superior to sodium chloride among patients with chronic renal failure undergoing catheterization and interventional procedures in preventing CIN was performed.

RESULTS

Data were combined across seven published clinical trials consisting of 1734 patients. There were no significant differences in the baseline characteristics between the NaHCO(3) and NaCl groups except patients in the bicarbonate group were heavier (P=0.04). The odds ratio (OR) for the development of contrast nephropathy for NaHCO(3) versus NaCl was 0.33 (95% confidence interval [CI] 0.16-0.69; P=0.003). Heterogeneity and publication bias were detectable with P-values 0.01 and 0.0005 respectively. There was no difference between the NaHCO(3) group and the NaCl group in the occurrence of death [OR 0.6; 95% CI (0.26-1.41); P=0.24], congestive heart failure [OR 0.85; 95% CI (0.32-2.24); P=0.74] and the requirement for renal replacement therapy [OR 0.56; 95% CI (0.22-1.41); P=0.22].

CONCLUSION

This meta-analysis demonstrates that based on currently available randomized trials, the administration of NaHCO(3) is superior to the administration of NaCl alone in the prevention of CIN among patients with moderate to severe chronic kidney disease. However, further controlled clinical trials are needed due to significant study heterogeneity and publication bias.