Use of dopamine in prevention of contrast induced acute renal failure--a randomised study

The Use of Low-Dose Dopamine in the Neonatal Intensive Care Unit

Dopamine has been used for half a century in adult and pediatric patients for the treatment of hypotension, as well as for the theoretical prevention of acute kidney injury (AKI). Although activation of renal dopamine receptors leads to increased urine output, there is no evidence that low-dose dopamine reduces the incidence of AKI, need for dialysis, or death. Dopamine administration is also associated with multiple adverse effects, particularly in preterm infants. Despite the lack of evidence for its use, as well as the known adverse effects of dopamine, many neonatologists still use low-dose dopamine to prevent or treat AKI in neonates. In this review, we provide a summary of our current medical knowledge about the use of low-dose dopamine in the neonatal population.

The Use of Low-Dose Dopamine in the Neonatal Intensive Care Unit

Dopamine has been used for half a century in adult and pediatric patients for the treatment of hypotension, as well as for the theoretical prevention of acute kidney injury (AKI). Although activation of renal dopamine receptors leads to increased urine output, there is no evidence that low-dose dopamine reduces the incidence of AKI, need for dialysis, or death. Dopamine administration is also associated with multiple adverse effects, particularly in preterm infants. Despite the lack of evidence for its use, as well as the known adverse effects of dopamine, many neonatologists still use low-dose dopamine to prevent or treat AKI in neonates. In this review, we provide a summary of our current medical knowledge about the use of low-dose dopamine in the neonatal population.

Contrast removal from coronary sinus for prevention of contrast-induced nephropathy: a review

The occurrence of contrast-induced-nephropathy (CIN) is related to the amount of contrast administration. Any removal of contrast from systemic circulation before reaching the kidneys might be beneficial using a device that removes contrast from a coronary sinus (CS). This manuscript aims to review the available literature regarding contrast removal from CS during coronary angiography or intervention for the prevention of CIN.

Obesity as a Risk Factor for Radiographic Contrast-Induced Nephropathy

Contrast-induced nephropathy (CIN) is common. Risk factors include preexisting renal impairment, diabetes, elderly age, and dehydration. In a single-centre prospective study, we investigated which factors are implicated for CIN in patients with peripheral arterial disease due for angiography. Serum creatinine was measured before, 1, 2, and 7 days post-angiography. We also considered the chronic kidney disease stage of the patients at admission and 48 hours post-contrast. All patients received 500 mL normal saline pre- and post-angiography and a low-osmolality contrast medium. 6 of 94 patients developed CIN: 1 required dialysis and 1 died partly due to renal failure. Only 2 factors were associated with CIN: body mass index (BMI; P = .019) and kidney function (P = .001); 4 of 6 patients with CIN were obese (BMI ≥30) and only 2 were nonobese (P = .0092). Diabetes, contrast volume, and age were not significant risk factors. Our results confirm renal impairment raises the risk of CIN. To our knowledge, we report for the first time that obesity may be a risk factor for CIN. Pending confirmatory studies and given the rising prevalence of obesity, this finding could help identify at-risk patients and hence reduce the burden of CIN.

Radiocontrast-Induced Acute Renal Failure

The intravascular administration of iodinated radiocontrast media can lead to acute renal dysfunction. Even small changes in renal function have been associated with increased morbidity and mortality, making the prevention of radiocontrast nephropathy of paramount importance. This review summarizes the principal risk factors for radiocontrast nephropathy and evidence-based preventive strategies that should be used to limit its occurrence. Risk factors for radiocontrast nephropathy include preexistent kidney disease, diabetes mellitus, dose of radiocontrast used, advanced congestive heart failure, and intravascular volume depletion. Proven preventive measures include volume expansion with intravenous saline or sodium bicarbonate and the use of low-osmolar or iso-osmolar radiocontrast media. Studies evaluating N-acetylcysteine have been conflicting, with meta-analyses suggesting a small beneficial effect. Studies of other pharmacologic agents have not demonstrated clinical benefit.

Tnf-α inhibition by infliximab as a new target for the prevention of glycerol-contrast-induced nephropathy

Contrast medium-induced nephropathy (CIN) remains as a problem with high incidence and mortality rates. The aim of this study is to examine the roles of infliximab (INF) in the glycerol (GLY) and CIN model in rats. The rats were separated into five groups (n=8): Healthy, GLY, GLY+CM, GLY+CM+INF 5mg/kg intraperitoneally (i.p.), and GLY+CM+INF 7 mg/kg (i.p.). Antioxidant levels in the therapy groups were observed to be quite similar to those in the healthy group. In this study, while the kidney TNF-α, IL-1β, TGF-1β and Caspase 3 gene expressions' levels increased in the nephrotoxic groups, these levels were found to have decreased in the treatment groups. Moreover, histopathologic examination showed that hyaline, haemorrhagic casts and necrosis were increased in nephrotoxicity group, whereas they decreased in the therapy group. Furthermore, TNF-α and NF-κB expression were decreased with infliximab administrated groups similar to control group. In conclusion, we suggest that infliximab have protective roles on CIN.

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.

Summary of clinical practice guidelines for acute kidney injury

Clinical practice guidelines are intended to standardize the diagnosis and treatment of diseases in order to improve both patient outcomes and resource utilization, using evidence-based criteria. As recently as a decade ago, there was no agreed upon definition of acute kidney injury (AKI), making it difficult to conduct proper clinical studies on the epidemiology and treatment of the disorder. Following the advent of the Risk, Injury, Failure, Loss, and End-stage (RIFLE) criteria for defining AKI, several guidelines for the diagnosis and management of AKI have been developed. In our review, we present a narrative description and comparison of the major published guidelines. Overall, there has been significant agreement among the various guidelines, and each seems well-reasoned and clinically useful. Perhaps the most striking conclusion upon review of the various guidelines is the limited scope of knowledge about optimal management of patients with AKI.

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 acute kidney injury following coronary angiography: a cohort study of hospitalized patients with or without chronic kidney disease

BACKGROUND

Contrast-induced acute kidney injury (CIAKI) has been linked to unfavorable consequences. In routine clinical practice, small increases in serum creatinine (SCr) following coronary angiography tend to be underestimated, especially in patients without chronic kidney disease (CKD).

METHODS

We conducted a retrospective observational cohort study to analyze in-hospital and long-term outcomes of CIAKI following coronary angiography in patients with or without CKD (eGFR ≥ 60 mL/min/1.73 m(2)) from January 2008 through December 2009. CIAKI was defined as SCr either ≥ 25% or ≥ 0.5 mg/dL from baseline within 72 h after contrast exposure. Multivariable logistic regression for in-hospital mortality and Cox proportional hazards calculations for long-term mortality and requirement for dialysis were performed.

RESULTS

A total of 1160 patients were included in the study. CIAKI occurred in 19% of CKD patients and in 18% of non-CKD patients. In CKD and non-CKD patients, CIAKI was more frequent in patients requiring mechanical ventilation or inotropes or in those given furosemide, and it was associated with adverse in-hospital (prolonged hospitalization, acute dialysis and mortality) and long-term (increased creatinine, initiation of dialysis and mortality) outcomes. In multivariable analysis, CKD patients had greater in-hospital mortality if they developed CIAKI (adjusted OR 8, 95% CI 1.9-34.5, P = 0.005), and non-CKD patients had greater long-term mortality if they developed CIAKI (adjusted HR 2.2, 95% CI 1.2-4.1, P = 0.016).

CONCLUSIONS

CIAKI following coronary angiography was associated with adverse in-hospital and long-term outcomes in both CKD and non-CKD patients.

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

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

Contrast-induced nephropathy in patients undergoing percutaneous coronary intervention

Contrast Induced Nephropathy (CIN) is a feared complication of numerous radiological procedures that expose patients to contrast media. The most notorious of these procedures is percutaneous coronary intervention (PCI). Not only is this a leading cause of morbidity and mortality, but it also adds to increased costs in high risk patients undergoing PCI. It is thought to result from direct cytotoxicity and hemodynamic challenge to renal tissue. CIN is defined as an increase in serum creatinine by either ≥0.5 mg/dL or by ≥25% from baseline within the first 2-3 days after contrast administration, after other causes of renal impairment have been excluded. The incidence is considerably higher in diabetics, elderly and patients with pre-existing renal disease when compared to the general population. The nephrotoxic potential of various contrast agents must be evaluated completely, with prevention as the mainstay of focus as no effective treatment exists. The purpose of this article is to examine the pathophysiology, risk factors, and clinical course of CIN, as well as the most recent studies dealing with its prevention and potential therapeutic interventions, especially during PCI. The role of gadolinium as an alternative to iodinated contrast is also discussed.

Preventing acute decrease in renal function induced by coronary angiography (PRECORD): a prospective randomized trial

BACKGROUND

Infusion of saline attenuates the decrease in renal function induced by radiographic contrast agents among patients with chronic renal insufficiency.

AIM

The Preventing Renal alteration in Coronary Disease (PRECORD) trial was a randomized trial to assess the effect on renal function of saline infusion during and after coronary angiography in 201 patients without severe chronic renal insufficiency (serum creatinine<140micromol/L).

METHODS

All patients received standard oral hydration: 2000mL of tap water within the 24 hours after coronary angiography. Patients were randomized before the procedure to intravenous hydration (1000mL of 0.9% saline infusion) or no additional hydration. The infusion was started in the catheterization laboratory and continued for 24 hours. The primary endpoint was the change in calculated creatinine clearance between baseline and 24 hours after coronary angiography. The same ionic low osmolar radiographic contrast agent (ioxaglate) was used in all patients.

RESULTS

Both groups had similar baseline characteristics, including age, serum creatinine, volume of contrast and proportion of patients undergoing ad hoc coronary angioplasty. The overall decrease in serum creatinine clearance 24 hours after the procedure was -3.44 (0.68)mL/min. The change in serum creatinine clearance 24 hours after the procedure was -2.81 (1.07)mL/min in the infusion group vs -4.09 (0.91)mL/min in the control group (p=0.38).

CONCLUSION

Renal function is altered only slightly 24 hours after coronary angiography with standard oral hydration alone and is not affected by saline infusion started at the beginning of coronary angiography, even in patients with mild-to-moderate renal dysfunction.

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.

Contrast-induced nephropathy

Contrast induced nephropathy (CIN) is an iatrogenic disorder, resulting from exposure to contrast media. Contrast-induced hemodynamic and direct cytotoxic effects on renal structures are highly evident in its pathogenesis, whereas other mechanisms are still poorly understood. CIN is typically defined as an increase in serum creatinine by either > or =0.5 mg/dl or by > or =25% from baseline within the first 2-3 days after contrast administration. Although rare in the general population, CIN has a high incidence in patients with an underlying renal disorder, in diabetics, and the elderly. The risk factors are synergistic in their ability to produce CIN. The best way to prevent CIN is to identify the patients at risk and to provide adequate peri-procedural hydration. The role of various drugs in prevention of CIN is still controversial and warrants future studies. Despite remaining uncertainty regarding the degree of nephrotoxicity produced by various contrast agents, in current practice non-ionic low-osmolar contrast media are preferred over the high-osmolar contrast media in patients with renal impairment.

HOpe for contrast-induced acute kidney injury

Contrast-induced nephropathy (CIN) is a common cause of acute kidney injury in hospitalized patients. The mechanisms involved in the pathogenesis of CIN are incompletely understood. Goodman et al. have demonstrated for the first time that heme oxygenase-1, a 32-kilodalton protein with antioxidant, antiapoptotic, anti-inflammatory effects, is induced in the kidney and, importantly, provides a beneficial effect in CIN.

Contrast-induced nephropathy

Interventional radiological procedures involving anaesthesia are generally increasing. Contrast-induced nephropathy (CIN), usually defined as an increase in serum creatinine of 44 micromol litre(-1) (0.5 mg dl(-1)) or a 25% increase from the baseline value 48 h after intravascular injection of contrast media, is a common and potentially serious complication of the use of iodinated contrast media in patients at risk of acute renal injury. It is an important cause of hospital-acquired renal failure, may be a difficult differential diagnosis and the incidence does not appear to have changed over the last few decades. In the general population, the incidence of CIN is estimated to be 1-2%. However, the risk for developing CIN may be as high as 50% in some patient subgroups, such as those with diabetes mellitus and pre-existing renal impairment. The impact of CIN on clinical outcomes has been evaluated most extensively in patients undergoing percutaneous coronary intervention where it is associated with increased mortality both in hospital and at 1 yr. As treatment is limited to supportive measures while awaiting the resolution of the renal impairment, emphasis needs to be directed at prevention.

Prevention of Contrast-Induced Nephropathy in the Emergency Department

STUDY OBJECTIVE

Contrast-induced nephropathy is the third leading cause of hospital-acquired acute renal failure. Expanded use of contrast-enhanced imaging exposes an ever-widening number of patients to this renal toxin. We perform an evidence-based emergency medicine review comparing different therapies to prevent contrast-induced nephropathy. We limit our review to prophylactic therapies that are practical for an emergency department setting.

METHODS

We searched MEDLINE, EMBASE, and the Cochrane Library for randomized trials comparing a wide range of medications to prevent contrast-induced nephropathy. We defined contrast-induced nephropathy by a commonly used surrogate measure of renal failure: a 25% or 0.5 mg/dL absolute increase in serum creatinine level from baseline 48 to 72 hours postcontrast. We limited our review to only trials for patients with baseline renal insufficiency, who are most at risk for contrast-induced nephropathy. We excluded prophylactic protocols requiring more than 2 hours precontrast to initiate and any trials of experimental medications or those that required invasive monitoring. We used standard criteria to appraise the quality of published trials.

RESULTS

We found 7 randomized trials; 3 using N-acetylcysteine, 2 using theophylline, and 1 each using bicarbonate and ascorbic acid. Although many of these trials showed statistically significant reductions in the risk for contrast-induced nephropathy, none were sufficiently powered to detect reductions in mortality rate or the need for dialytic therapy.

CONCLUSION

Evidence from randomized trials shows that these interventions (theophylline, bicarbonate, and ascorbic acid) under review were appropriate to an ED setting and decreased the risk of contrast-induced nephropathy. The case for the effectiveness (N-acetylcysteine) was less certain.

Strategies to reduce the risk of contrast-induced nephropathy

In view of the clinical importance of contrast-induced nephropathy (CIN), numerous potential risk-reduction strategies have been evaluated. Adequate intravenous volume expansion with isotonic crystalloid (1.0-1.5 mL/kg per hr) for 3-12 hours before the procedure and continued for 6-24 hours afterward can lessen the probability of CIN in patients at risk. There are insufficient data on oral fluids (as opposed to intravenous volume expansion) as a CIN-prevention strategy. No adjunctive medical or mechanical treatment has been proved to be efficacious in reducing risk for CIN. Prophylactic hemodialysis and hemofiltration have not been validated as effective strategies. The CIN Consensus Working Panel considered that, of the pharmacologic agents that have been evaluated, theophylline, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), ascorbic acid, and prostaglandin E(1) deserve further evaluation. N-acetylcysteine is not consistently effective in reducing the risk for CIN. Fenoldopam, dopamine, calcium channel blockers, atrial natriuretic peptide, and l-arginine have not been shown to be effective. Use of furosemide, mannitol, or an endothelin receptor antagonist is potentially detrimental. Nephrotoxic drugs should be withdrawn before contrast administration in patients at risk for CIN.

Risk prediction of contrast-induced nephropathy

In order to make appropriate decisions about clinical management, it is important for physicians to be able to stratify patients according to their risk for contrast-induced nephropathy (CIN). The most important risk marker for nephropathy after exposure to iodinated contrast media is preexisting renal impairment. The risk of CIN is elevated and becomes clinically important in patients with chronic kidney disease characterized by an estimated glomerular filtration rate <60 mL/min per 1.73 m(2). In patients with renal impairment, diabetes mellitus amplifies the risk of CIN and complicates postprocedure management. Other markers associated with an increased risk of CIN include cardiovascular disease, periprocedural hemodynamic instability, use of nephrotoxic drugs, and anemia. The effect of risk factors is additive, and the presence of multiple risk factors in the same patient can create a very high risk for CIN and acute renal failure requiring dialysis. Risk models incorporating baseline and periprocedural characteristics have been developed using data from large databases of percutaneous coronary intervention patients. These schemes are potentially valuable, but at present the most practical approach to risk prediction is based on a simple model incorporating renal function and diabetes mellitus.

Epidemiology and prognostic implications of contrast-induced nephropathy

Contrast-induced nephropathy (CIN), usually defined as an increase in serum creatinine of 0.5 mg/dL (44.2 mumol/L), or a 25% increase from the baseline value 48 hours after the procedure, is a common and potentially serious complication of the use of iodinated contrast media in patients at risk of acute renal injury. It is an important cause of hospital-acquired renal failure, responsible for approximately 11% of cases. CIN may be difficult to distinguish from cholesterol embolization, another cause of postprocedure renal impairment. The reported incidence of CIN varies depending on the patient population studied. The impact of postprocedural renal impairment on clinical outcomes has been evaluated most extensively in patients undergoing percutaneous coronary intervention. CIN is associated with increased mortality both in hospital and at 1 year. A higher incidence of in-hospital and late cardiovascular events, as well as longer hospital stays, has been reported in patients developing CIN. In a small proportion of patients, CIN is severe enough to require dialysis, and these patients have a particularly poor prognosis. Many of the risk markers for CIN are also predictive of a worse prognosis.

Contrast-induced nephropathy: Pharmacological prophylaxis

Contrast media-associated acute renal failure represents the third most common cause of in-hospital renal function deterioration after decreased renal perfusion and post-operative renal insufficiency. Although generally benign, this complication is associated with a mortality rate ranging from 3.8 to 64%, depending on the increase of creatinine concentration. Multiple drugs have been tested in an attempt to prevent this complication. Central to the pathophysiology of contrast-induced nephrotoxicity (CIN) is an alteration in renal hemodynamics. In an effort to reverse these hemodynamic changes, vasodilators and diuretics have been tested as prophylactic drugs. However, their effectiveness has not been confirmed. Recently, considerable interest has resulted from the initial positive data on the effectiveness of prophylactic administration of antioxidant compounds, such as acetylcysteine and ascorbic acid. In this review, we focus on the effectiveness of pharmacologic therapies for preventing CIN.

N-acetylcysteine and contrast-induced nephropathy: a meta-analysis of 13 randomized trials

BACKGROUND

Contrast-induced nephropathy (CIN) following coronary angiography increases morbidity and mortality. Randomized trials of small sample size have evaluated whether N-acetylcysteine (NAC) prevents CIN in patients with renal dysfunction.

METHODS

To conduct a meta-analysis of the randomized trials the following databases were searched: MEDLINE (1966-2003), Cochrane Controlled Trials Register, ACP Journal Club online, published abstracts presented at the major cardiology and nephrology meetings, references from reviews. Two authors independently evaluated all relevant randomized trials. Eligibility criteria were (1) randomized placebo controlled trials of NAC, (2) patients with impaired renal function (creatinine >1.2 mg/dL) undergoing coronary angiography, (3) patients receiving intravenous fluids and low-osmolarity nonionic contrast media, (4) the primary outcome was CIN (increases in creatinine of either at least 0.5 mg/dL or 25% from baseline to 48 hours). Of 589 trials reviewed 3 disagreements were easily resolved by mutual discussion and 13 were selected. Data extraction included patient characteristics, intravenous fluid regimen, type and dose of contrast media, dosing regimen, creatinine at baseline and 48 hours and CIN requiring dialysis.

RESULTS

Four of the 13 trials reported statistically significant results. In meta-analysis of the 13 trials, which included 1892 patients, the RR was 0.68 (95%CI, 0.46-1.01). The addition of the trial of patients undergoing computerized tomography, which had formulated the hypothesis, yielded a statistically significant reduction (RR 0.64 [95%CI 0.42-0.96]) as did an earlier meta-analysis of 7 trials.

CONCLUSIONS

Our meta-analysis of the most currently available randomized data concerning NAC before coronary angiography to prevent CIN in patients with impaired renal function is neither conclusive nor provides proof beyond a reasonable doubt to influence clinical practice and public policy. The intervention has minimal toxicity but the width of the 95% CI remains compatible with a range from a large benefit to none at all. In addition, the trials used change in creatinine as the measure of outcome. Further randomized trials of large sample size and with clinical outcomes will add importantly relevant information to the totality of evidence and allow the most rational clinical decisions for individual patients as well as policy decisions for the health of the general public.

Prehydration Alone is Sufficient to Prevent Contrast-induced Nephropathy after Day-only Angiography Procedures—A Randomised Controlled Trial

BACKGROUND

Contrast agents used in angiography procedures for patients with cardiovascular disease are known to cause contrast-induced nephropathy (CIN), which may be partially due to the production of nephrotoxic oxygen-free radicals. It is uncertain whether administration of intravenous (IV) anti-oxidant, N-acetylcysteine (NAC), can prevent reduction in renal function and whether this is a cost-effective approach.

METHODS

Sixty-five day-only patients with renal impairment (mean serum creatinine concentration 0.16+/-0.03 mmol/l) due to undergo coronary or peripheral angiography and/or stenting were randomly assigned to IV NAC 300 or 600 mg immediately before and after the procedure or IV fluid alone.

RESULTS

Of the 60 patients with complete data, none had acute CIN (increase in serum creatinine concentration > or = 0.044 mmol/l, 48 h after administration of contrast agent). Eight patients (13%) have demonstrated an increase in their serum creatinine concentration > or = 0.044 mmol/l 30 days after administration of contrast agent: 2/19 (11%) in the control group, 2/21 (10%) in the 600 mg NAC group and 4/20 (20%) the 300 mg NAC group (p = 0.66). The mean volumes of contrast agent used and prehydration given for each of the three groups did not differ significantly (p > 0.83). There was significant improvement in creatinine clearance within each group from baseline to 30 days (p < or = 0.03), but no significant difference between the groups at 48 h and 30 days (p > or = 0.43). Considering the cost of NAC and its administration, we estimate that this would translate to a saving of dollar 26,637 per annum.

CONCLUSION

For day-stay patients with mild-to-moderate chronic renal impairment undergoing angiography and/or intervention, prehydration alone is less complicated and more cost-effective than a combination of IV NAC (at doses used) and hydration.

Reducing the Risks for Contrast-Induced Nephropathy

Contrast-induced nephropathy (CIN) is one of the most serious adverse events associated with the use of contrast media (CM). Patients who develop this complication can have increased morbidity, higher rates of mortality, lengthy hospital stays, and poor long-term outcomes. Although CIN cannot be eliminated, the chances of developing this condition can be reduced by using appropriate prevention strategies. An important first step to reduce the chance of CIN is to identify risk factors associated with this condition. Patients with a previously elevated serum creatinine level, especially when secondary to diabetic nephropathy, are at great risk for developing CIN. Other patient-related risk factors include concurrent use of nephrotoxic medications, dehydration, congestive heart failure, age greater than 70 years, and probably the presence of diabetes mellitus even if serum creatinine is normal. Adequate hydration is widely accepted as an important prophylactic measure for preventing CIN, but the optimal hydration regimen is still debatable. The risk of CIN increases with greater doses of CM, as well as with the type of CM used. A high-osmolar CM poses a greater risk of CIN than does a low-osmolar CM and, as recent but limited data suggest, the use of an isoosmolar CM is less nephrotoxic than a low-osmolar CM in patients with renal impairment following intra-arterial procedures, although this finding needs to be verified in future clinical studies. Pharmacologic agents such as calcium channel blockers, dopamine, atrial natriuretic peptide, fenoldopam, prostaglandin El, and endothelin receptor antagonist have not been proven effective against CIN development. Controversies still exist on the possible effectiveness of theophylline and N-acetylcysteine. Simple strategies for the prevention of CIN in at-risk patients are reviewed and unproven interventions are discussed.

Nephropathy induced by contrast media: pathogenesis, risk factors and preventive strategies

With the increasing use of contrast media in diagnostic and interventional procedures, nephropathy induced by contrast media has become the third leading cause of hospital-acquired acute renal failure. It is also associated with a significant risk of morbidity and death. The current understanding of the pathogenesis indicates that contrast-medium nephropathy is caused by a combination of renal ischemia and direct toxic effects on renal tubular cells. Patients with pre-existing renal insufficiency, diabetes mellitus and congestive heart failure are at highest risk. Risk factors also include the type and amount of contrast medium administered. Therapeutic prevention strategies are being extensively investigated, but there is still no definitive answer. In this article, we review the current evidence on the causes, pathogenesis and clinical course of contrast-medium nephropathy as well as therapeutic approaches to its prevention evaluated in clinical trials.

Contrast-induced nephropathy: a review

Contrast-induced nephropathy (CIN) is one of the leading causes of renal impairment in the United States and the third cause of hospital-acquired renal failure. Reduction in the incidence of CIN can lead to a decrease in the morbidity, mortality, and length of hospital stay. Although prophylactic hydration has been promising in decreasing the occurrence of CIN, other efforts such as diuretics, calcium channel blockers, theophylline, aminophylline, atrial natriuretic peptide, dopamine, and fenoldopam have been disappointing. The preventive effect of N-acetylcysteine on CIN has not been consistent in the literature. In a recent clinical trial, bicarbonate infusion was more effective than hydration in the prevention of CIN. Mechanical devices are in development to perfuse renal arteries with protective drugs during contrast exposure or for removal of contrast from coronary sinus during coronary angiography. In this article, we have reviewed available data in regards to CIN.

Prevention of contrast-induced nephropathy in vascular patients undergoing angiography: A randomized controlled trial of intravenous N-acetylcysteine

OBJECTIVE(S)

Apart from proper hydration, only oral N-acetylcysteine (NAC) has shown efficacy in reducing radiographic contrast media (RCM)-induced acute renal failure, though its benefit has been challenged. We investigated the effect of intravenous (i.v.) NAC on renal function in patients with vascular disease receiving RCM for angiography.

METHODS

Single-center, randomized, double-blind, placebo-controlled trial. Based on a previous study, a trial with 44 patients each in placebo and treatment arms would give at least 80% power to show a statistically significant difference at the 5% level. Vascular patients undergoing angiography were consented and segregated into those whose serum creatinine (SC) level was normal or raised (men >1.32 mg/dl; women >1.07 mg/dL). All patients received 500 mL i.v. normal saline 6 to 12 hours prior to and then after angiography. Groups with normal SC and raised SC were randomly assigned to either 1 g of NAC with normal saline before and after angiography or nothing (placebo). Main outcome measures were change in SC and creatinine clearance (CrCl) as measured 1, 2, and 7 days postangiography (with comparison between active and placebo groups using unpaired t test) and incidence of acute renal decline (>25% or 0.5 mg/dL rise in SC) at 48 hours (with comparison between active and placebo using the Fisher exact test).

RESULTS

Forty-six patients received NAC (29 normal SC, 17 raised SC), and 48 received placebo (27 normal SC, 21 raised SC). There was no significant difference in postangiography SC or CrCl at any of the time points measured between NAC and placebo in patients with either normal or raised SC. In the raised SC group, 3 patients from both the NAC and placebo groups suffered acute renal declines. Importantly, at 48 hours, the impaired SC group had a significant reduction in CrCl (-14% +/- 41% vs +18% +/- 58%: P = .0142) and a significant rise in SC (+7.0 +/- 25% vs -1.6% +/- 10%; P = .0246) when compared with the normal SC group.

CONCLUSIONS

NAC (i.v. at 1 g) precontrast and postcontrast does not confer any benefit in preventing RCM-induced nephropathy in vascular patients. Patients with pre-existing raised SC have an increased risk of renal impairment as defined by a fall in CrCl and a rise in SC post-RCM when compared with patients with normal SC who appear to benefit from hydration.

Effect of N-acetylcysteine for prevention of contrast nephropathy in patients with moderate to severe renal insufficiency: a randomized trial

BACKGROUND

The effect of N-acetylcysteine (NAC) to prevent contrast nephropathy (CN) in patients with moderate to severe renal insufficiency undergoing coronary angiography or interventions is not clear.

METHODS

This is a prospective, open-label, randomized, controlled trial. Ninety-one consecutive patients with a serum creatinine level of 1.69 to 4.52 mg/dL (149 to 400 micromol/L) undergoing coronary procedures were recruited and randomly assigned to administration of either oral NAC, 400 mg, thrice daily the day before and day of the contrast procedure (the NAC group) or no drug (the control group). Serum creatinine was measured before and 48 hours after contrast exposure. The primary end point of this study was the development of CN, defined as an increase in serum creatinine concentration of 0.5 mg/dL or greater (> or =44 micromol/L) or a reduction in estimated glomerular filtration rate (GFR) of 25% or greater of the baseline value 48 hours after the procedure.

RESULTS

There were no significant differences between the 2 groups (46 patients, NAC group; 45 patients, control group) in baseline characteristics or mean volume of contrast agent administered. Six patients (13.3%) in the control group and 8 patients (17.4%) in the NAC group developed CN (P = 0.8). Serum creatinine levels increased from 2.27 +/- 0.54 to 2.45 +/- 0.65 mg/dL (201 +/- 48 to 217 +/- 57 micromol/L; P = 0.003) in the NAC group and 2.37 +/- 0.61 to 2.40 +/- 0.70 mg/dL (210 +/- 54 to 212 +/- 62 micromol/L; P = 0.6) in the control group. The increase in serum creatinine levels between the 2 groups had no difference (P = 0.7). Estimated GFR decreased from 30.3 +/- 8.4 to 28.1 +/- 8.4 mL/min (P = 0.01) in the NAC group and 28.4 +/- 8.6 to 27.5 +/- 8.8 mL/min (P = 0.3) in the control group. The decline in estimated GFR between the 2 groups had no difference (P = 0.7).

CONCLUSION

In the current study, oral NAC had no effect on the prevention of CN in patents with moderate to severe renal insufficiency undergoing coronary angiography or interventions. However, the sample size of our present study is small. Our findings highlight the need for a large-scale, randomized, controlled trial to determine the exact beneficial effect of NAC.

Preventing contrast nephropathy: what is the best strategy? A review of the literature

Patients receiving radiocontrast for diagnostic and interventional procedures are at risk for developing contrast nephropathy (CN). In fact, radiocontrast nephropathy is currently the third leading cause of hospital-acquired renal failure. Understanding that CN has been associated with increased length of hospitalization and mortality, determining the best prevention strategy is of utmost importance. Patients at the greatest risk for developing acute renal failure are patients with diabetes and underlying renal insufficiency. Several therapies have been investigated for the prevention of CN; unfortunately, very few have shown a consistent benefit. Therapies that have been studied include saline hydration, N-acetylcysteine (NAC), theophylline, calcium channel blockers, diuretics, dopamine, endothelin receptor antagonists, atrial natriuretic peptide, angiotensin-converting enzyme inhibitors, and prostaglandin E-1. Using adequate hydration, using low-osmolar dyes, and minimizing the dose of contrast have all been shown to be effective in reducing CN and are considered the standard of care. While trials with many pharmacologic agents have produced conflicting results, intervention with NAC has also been promising. This article reviews the pathophysiology, risk factors, and therapies that are currently available for the prevention of CN.

Prophylaxis of Iodinated Contrast Media-Induced Nephropathy

Iodinated contrast media are a frequent cause of acute renal failure, especially in patients whose renal function is already impaired. In addition to hydration, which remains the most commonly acknowledged means of protection, numerous pharmacological approaches for the prophylaxis of contrast nephropathy have been tested so far. They include diuretics, calcium channel blockers, adenosine receptor antagonists, N-acetylcysteine, low-dose dopamine and the dopamine D1 receptor agonist fenoldopam, endothelin receptor antagonists, and even captopril. The present review of the literature critically discusses the drugs used to prevent contrast nephropathy from a pharmacological point of view.

Duplex ultrasound-guided femoropopliteal angioplasty: initial and 12-month results from a case controlled study

PURPOSE

To evaluate initial technical success, procedural complications, and 12-month patency of duplex-guided angioplasty compared to conventional fluoroscopically-guided procedures.

METHODS

One hundred four patients (65 men; mean age 69 years) who underwent duplex-guided femoropopliteal angioplasty were compared to 104 patients undergoing fluoroscopically-guide procedures who were matched for age, sex, baseline ankle-brachial index (ABI), and length and grade of lesion. Patients were followed for 12 months, and restenosis was assessed by ABI and duplex sonography.

RESULTS

Technical success was achieved in 88 (84.6%) patients from the duplex-guided group and in 102 (98.1%) control patients (p=0.001). Periprocedural complications occurred in 12.5% (n=13) and 18.3% (n=19), respectively (p=0.4). Contrast-induced transient renal impairment was observed in 7 (6.7%) patients in the fluoroscopic group. One hundred (96.1%) patients in the duplex and 102 (98.1%) patients in the fluoroscopic group completed the 12-month follow-up. Restenosis was found in 35 (39.8%) patients of the duplex group and in 38 (37.2%) patients of the fluoroscopic group (p=0.8).

CONCLUSIONS

Technical success of duplex-guided procedures was significantly lower compared to fluoroscopic angioplasty; complications and 12-month patency were similar with both techniques. Duplex-guided angioplasty may be a feasible alternative, particularly for patients at high risk for contrast-induced complications.

Acetylcysteine protects against acute renal damage in patients with abnormal renal function undergoing a coronary procedure

OBJECTIVES

We sought to evaluate the efficacy of the antioxidant acetylcysteine in limiting the nephrotoxicity after coronary procedures.

BACKGROUND

The increasingly frequent use of contrast-enhanced imaging for diagnosis or intervention in patients with coronary artery disease has generated concern about the avoidance of contrast-induced nephrotoxicity (CIN). Reactive oxygen species have been shown to cause CIN.

METHODS

We prospectively studied 121 patients with chronic renal insufficiency (mean [+/-SD] serum creatinine concentration 2.8 +/- 0.8 mg/dl) who underwent a coronary procedure. Patients were randomly assigned to receive either acetylcysteine (400 mg orally twice daily) and 0.45% saline intravenously, before and after injection of the contrast agent, or placebo and 0.45% saline. Serum creatinine and blood urea nitrogen were measured before, 48 h and 7 days after the coronary procedure.

RESULTS

Seventeen (14%) of the 121 patients had an increase in their serum creatinine concentration of at least 0.5 mg/dl at 48 h after administration of the contrast agent: 2 (3.3%) of the 60 patients in the acetylcysteine group and 15 (24.6%) of the 61 patients in the control group (p < 0.001). In the acetylcysteine group, the mean serum creatinine concentration decreased significantly from 2.8 +/- 0.8 to 2.5 +/- 1.0 mg/dl (p < 0.01) at 48 h after injection of the contrast medium, whereas in the control group, the mean serum creatinine concentration increased significantly from 2.8 +/- 0.8 to 3.1 +/- 1.0 mg/dl (p < 0.01).

CONCLUSIONS

Prophylactic oral administration of the antioxidant acetylcysteine, along with hydration, reduces the acute renal damage induced by a contrast agent in patients with chronic renal insufficiency undergoing a coronary procedure.

Reduction in renal function after renal arteriography and after renal artery angioplasty

OBJECTIVE

To investigate the incidence and risk factors for renal function deterioration after renal angiography and angioplasty or stenting.

METHODS

A retrospective study of 85 consecutive patients undergoing selective renal artery arteriography (n = 53) or renal artery angioplasty % (PTRA) stenting (n = 32) for renal artery stenosis. Multivariate logistic regression analysis was used to determine independent predictors of deterioration of renal function, defined as an increase of serum creatinine by at least one third within 24 h.

RESULTS

Deterioration of renal function occurred in 13 patients (15%), [8/53 (15%) after angiography and 5/32 (16%) after PTRA/stenting]. Only pre-existing renal impairment (se-creatinine > or = 177 mumol/l) (Odds ratio: 40; 95% confidence interval 1.2-72, p = 0.02) and administered dosage of contrast agent (more than 225 ml) (OR 67; 95% CI 11.8-100, p = 0.02) were independently associated with renal function deterioration.

CONCLUSION

Transient renal dysfunction after renal artery angiography or PTRA/stenting occurs in about 15% of patients, but persistent renal failure is uncommon. Pre-existing renal impairment and amount of contrast agent are independent risk factors. Endovascular treatment of renal artery stenosis is not associated with a higher risk of renal deterioration compared to selective renal angiography.

Predicting renal failure after balloon angioplasty in high-risk patients

PURPOSE

To assess the incidence and predictors of acute renal failure after percutaneous transluminal angioplasty (PTA) in a cohort of patients with generalized atherosclerosis.

METHODS

A retrospective review of 213 consecutive patients (127 men; median age 71 years, interquartile range 63-77) undergoing femoropopliteal PTA was undertaken. Renal function was measured by creatinine clearance at baseline and 24 hours after the intervention; acute renal dysfunction was defined as > or = 20% decrease of creatinine clearance. The predictive value of potential risk factors was determined in a multivariate model adjusting for comorbidities, pre-existing renal impairment, and angiographic data.

RESULTS

Overall serum creatinine values and creatinine clearance remained stable within 24 hours after PTA. Acute renal dysfunction occurred in 25 (12%) patients. Two (1%) patients developed oliguria; one required transient hemodialysis and developed persistent renal failure. Pre-existing impaired renal function (OR 12.2, p < 0.0001) and contrast dosage (OR 1.1, p = 0.03) were independent predictors of acute renal failure; hypertension (OR 7.9, p = 0.06) and congestive heart failure (OR 4.5, p = 0.06) were associated factors.

CONCLUSIONS

While transient acute renal dysfunction occurs in approximately 10% of patients with peripheral artery disease within 24 hours after angioplasty, persistent renal failure or end-stage renal disease is rare.

Prediction and prevention of contrast nephropathy

Over the last 10 years, the main advances in RCN have come in our ability to predict outcomes for an individual patient. Treatment trials have been almost all uniformly disappointing. Recent positive trials with acetylcysteine and PGE1 will require confirmation in larger trials that are adequately powered for meaningful end points in the PCI population. In the meantime, adequate prehydration and maintenance of post-PCI urine flow rates of > 150 mL/min remain the most prudent measures. As the population ages, breakthroughs with respect to new contrast agents or effective prevention measures will be needed to offer PCI to the spectrum of patients at risk for renal injury.