Contrast medium-induced acute renal failure and cholesterol embolism after radiological procedures: incidence, risk factors, and compliance with recommendations

Ischemic small bowel perforation caused by cholesterol crystal embolism following transcatheter arterial chemoembolization for recurrent hepatocellular carcinoma: a case report

Background

Cholesterol crystal embolism (CCE) following transcatheter arterial chemoembolization (TACE) is rare.

Case presentation

A 71-year-old man underwent TACE for recurrence of hepatocellular carcinoma (HCC). On postoperative day (POD) 5, he developed abdominal pain and fever. Computed tomography revealed intraperitoneal free air. The patient was diagnosed with gastrointestinal perforation with peritonitis, for which partial intestinal resection and covering ileostomy were performed. Histological examination revealed perforation of the small intestine caused by CCE. The patient made a satisfactory recovery and was discharged on POD 30. The patient showed no recurrence of cholesterol crystal embolism or HCC for 2 years after surgery.

Conclusion

We reported a successfully treated case of ischemic small bowel perforation due to cholesterol crystal embolism following transcatheter arterial chemoembolization for recurrent HCC.

Baseline atrial fibrillation is associated with contrast-induced nephropathy after cardiac catheterization in coronary artery disease: Systemic review and meta-analysis

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia, independently associated with significant mortality and morbidity. Recent studies suggest that AF is potentially associated with contrast-induced nephropathy (CIN) in patients with coronary artery disease (CAD) undergoing catheterization. However, the association was not conclusive. Thus, we assessed the association between AF in patients with CAD and CIN by a systematic review of the literature and a meta-analysis.

HYPOTHESIS

AF is a predictor of CIN in patients with CAD.

METHODS

We comprehensively searched the databases of MEDLINE and EMBASE from inception to April 2018. Included studies were published observational studies that compared the risk of CIN among CAD patients with AF vs those without AF. Data from each study were combined using the random-effects, generic inverse variance method of DerSimonian and Laird to calculate risk ratios and 95% confidence intervals (CIs).

RESULTS

Eight cohort studies from June 2007 to November 2017 were included in this meta-analysis involving 16,691 subjects with CAD (1,030 with AF and 15,661 without its presence). The presence of AF was associated with CIN (pooled risk ratio = 2.17, 95% CI: 1.50-3.14, P < 0.001, I² = 54.1%). In our subgroup analysis by urgency and multivariable adjustment, both groups still showed substantial association between AF and CIN (P < 0.05).

CONCLUSIONS

AF increased the risk of CIN up to two fold among patients with CAD compared to the absence of it. Our study suggests that the presence of AF in CAD is prognostic for the development of CIN.

The predictive value of the product of contrast medium volume and urinary albumin/creatinine ratio in contrast-induced acute kidney injury

Preexisting renal impairment and the amount of contrast media are the most important risk factors for contrast-induced acute kidney injury (CI-AKI). We aimed to investigate whether the product of contrast medium volume and urinary albumin/creatinine ratio (CMV × UACR) would be a better predictor of CI-AKI in patients undergoing nonemergency coronary interventions. This was a prospective single-center observational study, and 912 consecutive patients who were exposed to contrast media during coronary interventions were investigated prospectively. CI-AKI is defined as a 44.2 μmol/L rise in serum creatinine or a 25% increase, assessed within 48 h after administration of contrast media in the absence of other causes. Fifty patients (5.48%) developed CI-AKI. The urinary albumin/creatinine ratio (UACR) (OR = 1.002, 95% CI = 1.000–1.003, p = .012) and contrast medium volume (CMV) (OR = 1.008, 95% CI = 1.001–1.014, p = .017) were independent risk factors for the development of CI-AKI. The area under the ROC curve of CMV, UACR and CMV × UACR were 0.662 (95% CI = 0.584–0.741, p < .001), 0.761 (95% CI = 0.674–0.847, p < .001) and 0.808 (95% CI = 0.747–0.896, p < .001), respectively. The cutoff value of CMV × UACR to predict CI-AKI was 1186.2, with 80.0% sensitivity and 62.2% specificity. The product of CMV and UACR (CMV × UACR) might be a predictor of CI-AKI in patients undergoing nonemergency coronary interventions, which was superior to CMV or UACR alone.

Contrast induced-acute kidney injury following peripheral angiography with carbon dioxide versus iodinated contrast media: A meta-analysis and systematic review of current literature

OBJECTIVE

We conducted a meta-analysis to compare the incidence of acute kidney injury (AKI) with carbon dioxide (CO₂ ) versus iodinated contrast media (ICM).

BACKGROUND

Contrast induced-acute kidney injury (CI-AKI) is a known complication following endovascular procedures with ICM. CO₂ has been employed as an alternative imaging medium as it is nontoxic to the kidneys.

METHODS

Search of indexed databases was performed and 1,732 references were retrieved. Eight studies (7 observational, 1 Randomized Controlled Trial) formed the meta-analysis. Primary outcome was AKI. Fixed effect model was used when possible in addition to analysis of publication bias.

RESULTS

In this meta-analysis, 677 patients underwent 754 peripheral angiographic procedures. Compared with ICM, CO₂ was associated with a decreased incidence of AKI (4.3% vs. 11.1%; OR 0.465, 95% CI: 0.218-0.992; P = 0.048). Subgroup analysis of four studies that included granular data for patients with chronic kidney disease (CKD) did not demonstrate a decreased incidence of AKI with CO₂ (4.1% vs. 10.0%; OR 0.449, 95% CI: 0.165-1.221, P = 0.117). Patients undergoing CO₂ angiography experienced a higher number of nonrenal events including limb/abdominal pain (11 vs. 0; P = 0.001) and nausea/vomiting (9 vs. 1; P = 0.006).

CONCLUSIONS

In comparison to ICM, CO₂ use is associated with a modestly reduced rate of AKI with more frequent adverse nonrenal events. In studies that use CO₂ as the primary imaging agent, the average incidence of AKI remained high at 6.2%-supporting the concept that factors other than renal toxicity from ICM may contribute to renal impairment following peripheral angiography. © 2017 Wiley Periodicals, Inc.

Impact of low hemoglobin on the development of contrast-induced nephropathy: A retrospective cohort study

An increase in the use of iodinated contrast media, such as iohexol, iodixanol, iopamidol and iopromide, occasionally causes contrast-induced nephropathy (CIN) in patients undergoing coronary angiography (CAG) and/or percutaneous coronary intervention (PCI). The present study aimed to assess the effects of low levels of hemoglobin on the development of CIN in patients with normal renal function following CAG/PCI. A total of 841 consecutive patients undergoing CAG/PCI were divided into two groups: Patients with low levels of hemoglobin (male, <120 g/l; female, <110 g/l; n=156) and normal levels of hemoglobin (male, 120-160 g/l; female, 110-150 g/l; n=685). Multiple logistic regression analysis was performed to identify risk factors for CIN, which developed in 14.7% of patients with low levels of hemoglobin (relative risk, 3.07) and 5% of patients with normal levels of hemoglobin (P<0.01). Independent risk factors for developing CIN in patients with low levels of hemoglobin were a contrast media volume ≥200 ml, diuretic usage, low levels of hemoglobin and diabetes mellitus. For the patients with normal hemoglobin levels, the independent risk factors for developing CIN were a contrast media volume ≥200 ml and diuretic usage. The change in serum creatinine in patients with low levels of hemoglobin was significantly greater compared with patients with normal levels of hemoglobin (7.35±22.60 vs. 1.40±12.00; P<0.01). A similar incidence of developing CIN was observed when patients were administered each type of contrast media: Iohexol, iodixanol, iopamidol and iopromide. The optimal cut-off point at which the serum hemoglobin concentration resulted in a high probability of developing CIN was determined as 111.5 g/l in females and 115.5 g/l in males. In conclusion, low levels of hemoglobin were observed to be an independent risk factor for developing CIN. Patients with reduced hemoglobin levels should, therefore, be closely monitored prior to, and during, the administration of iodinated contrast media.

Utility of the Logistic Clinical Syntax Score in the Prediction of Contrast-Induced Nephropathy After Primary Percutaneous Coronary Intervention

BACKGROUND

The Logistic Clinical Syntax Score (log CSS) is a combined risk scoring system that includes clinical and anatomic parameters; it has been found to be effective for the prediction of mortality in patients with ST-elevation myocardial infarction (STEMI). The aim of the present study was to assess whether the log CSS was associated with the development of contrast-induced nephropathy (CIN) in patients who underwent primary percutaneous coronary intervention (pPCI).

METHODS

A total of 930 patients with STEMI undergoing pPCI between January 2012 and August 2013 were included prospectively. The patients were grouped according to the development of CIN. Either an absolute serum creatinine level ≥ 0.5 mg/dL or a 25% increase in the serum creatinine level compared with the baseline level within 48 hours after the administration of contrast medium was defined as CIN.

RESULTS

The Synergy Between Percutaneous Coronary Interventions With Taxus and Cardiac Surgery score (SYNTAX [SS]) and log CSS were higher in patients with CIN than in those without. In the multivariate analysis, log CSS (odds ratio, 1.405, 95% confidence interval, 1.318-1.497; P < 0.001), hemoglobin, and contrast volume were found to be independent predictors of CIN. In the receiver operating characteristic analysis, a log CSS > 9.5 had a 74.5% sensitivity and a 90.5% specificity for predicting CIN, with an area under the curve (AUC) of 0.892, whereas an SS > 18.5 had a 64% sensitivity, a 58.1% specificity, and an AUC of 0.625 (0.892 vs 0.625; P < 0.001). A log CSS > 9.5 was associated with in-hospital and long-term mortality, reinfarction, revascularization, and in-hospital hemodialysis (P < 0.001 for each).

CONCLUSIONS

The log CSS may improve the accuracy of risk stratification for the development of CIN in patients undergoing pPCI.

Acute Kidney Injury in Critically Ill Vascular Surgery Patients is Common and Associated with Increased Mortality

INTRODUCTION

Vascular surgery patients have multiple risk factors for renal dysfunction, but acute kidney injury (AKI) is poorly studied in this group. The purpose of this study was to define the incidence, risk factors, and outcomes of AKI in high-risk vascular patients.

METHODS

Critically ill vascular surgery patients admitted during January-December 2012 were retrospectively analyzed with 1-year follow-up. The endpoint was AKI by established RIFLE creatinine criteria. The primary analysis was between patients with or without AKI, with secondary analysis of post-operative AKI. Outcomes were inpatient and 1-year mortality, inpatient lengths of stay, and discharge renal function.

RESULTS

One-hundred and thirty six vascular surgery patients were included, representing 27% of all vascular surgery admissions during the study period. Sixty-five (48%) developed AKI. Independent global risk factors for AKI were diabetes, increasing critical illness severity, and sepsis. While intraoperative blood loss and hypotension were associated with subsequent renal dysfunction, post-operative AKI rates were similar for patients undergoing aortic, carotid, endovascular, or peripheral vascular procedures. All RIFLE grades of AKI were associated with worse outcomes. Overall, patients with AKI had significantly increased short- and long-term mortality, longer inpatient lengths of stay, and worse discharge renal function.

CONCLUSION

AKI is common among critically ill vascular surgery patients. Importantly, the type of surgical procedure appears to be less important than intra- and perioperative management in determining renal dysfunction. Regardless of its severity, AKI is a clinically significant complication that is associated with substantially worse patient outcomes.

Predictive factors of contrast-induced nephropathy in patients undergoing primary coronary angioplasty

BACKGROUND

Contrast-induced nephropathy (CIN) severely impacts patient morbidity and mortality, especially in patients with ST-segment elevation myocardial infarction treated by primary coronary angioplasty, whose renal function is often unknown at the time of contrast exposure.

AIM

We sought the incidence and factors predictive of CIN in patients treated by primary coronary angioplasty in our hospital; we also questioned the relevance of Mehran's risk score in this population.

METHODS

We considered all patients admitted for primary coronary angioplasty between January 2010 and December 2011, and included 322 patients with complete data on renal function. CIN was defined as a relative (≥25%) or absolute (≥44 μmol/L) increase in serum creatinine following contrast medium administration. We compared patients with or without CIN, to identify predictive factors, and investigated the effectiveness of Mehran's score using a receiver operating characteristic (ROC) curve, Youden's index and a likelihood ratio test.

RESULTS

The incidence of CIN was 9.1%. A multivariable analysis identified two independent risk factors for CIN: impaired glomerular filtration rate and cardiogenic shock at admission (P<0.05). An elevated Mehran's score was associated with increased incidence of CIN, but statistical analysis revealed this score to have poor sensitivity, especially in high-risk patients. Youden's index was very low and the area under the ROC curve was 0.59 in our population.

CONCLUSION

Renal failure and cardiogenic shock at admission were independent predictors of CIN in our acute myocardial infarction population. Mehran's score added little to the discrimination of patients undergoing primary coronary angioplasty, particularly high-risk individuals.

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.

Relation of the severity of contrast induced nephropathy to SYNTAX score and long term prognosis in patients treated with primary percutaneous coronary intervention

BACKGROUND

SYNTAX score (SXscore) has been developed to assess the severity and complexity of coronary artery disease. The aim of this study was to evaluate whether baseline SXscore was associated with contrast induced nephropathy (CIN) after primary percutaneous coronary intervention (p-PCI) in patients with ST-elevation myocardial infarction (STEMI). Secondarily we aimed to investigate the relation of the severity of CIN to long term prognosis.

METHODS

We retrospectively enrolled 1893 patients with STEMI treated by p-PCI. We prospectively followed up the patients for a mean duration of 45 months. The patients were grouped according to the development of no nephropathy (grade 0, n: 1634), mild nephropathy (grade 1, n: 153) or severe nephropathy (grade 2, n: 106).

RESULTS

SXscore was significantly higher (19.4±5.9 vs 15.6±4.8, p<0.001) in patients with CIN (grades 1 and 2) compared to those without CIN. SXscore was higher in patients with grade 2 CIN compared to those with grade 1 CIN (18.5±5.7 vs 20.7±5.9, p<0.001). In the multivariate analysis, SXscore was identified as an independent predictor of CIN (for one unit increment, OR: 1.06, 95% CI: 1.01-1.14, p=0.006). At long-term follow-up, death (p<0.001), stroke (p=0.006), reinfarction (p=0.024) and permanent HD requirement (p<0.001) were most frequent in grade 2 nephropathy group. HD was associated with very high in-hospital (60%) and long-term (83.3%) mortality rates.

CONCLUSIONS

SXscore is an independent predictor of development and severity of CIN after p-PCI. CIN is associated with poor prognosis during both early and late postinfarction period.

Contrast-induced acute kidney injury following PCI

BACKGROUND

Coronary revascularization using percutaneous coronary intervention (PCI) is one of the major treatments for patients with stable coronary artery disease, with approximately 1.5 million patients undergoing PCI in the United States and Europe every year. An important neglected complication of PCI is contrast-induced acute kidney injury (CI-AKI).

DESIGN

In this article, we review the definition, pathogenesis and management of CI-AKI and highlight potential therapeutic options for preventing CI-AKI in post-PCI patients.

RESULTS

CI-AKI is an important but underdiagnosed complication of PCI that is associated with increased in-hospital morbidity and mortality. Patients with pre-existing renal impairment and diabetes are particularly susceptible to this complication post-PCI. Optimization of the patients' circulating volume remains the mainstay for preventing CI-AKI, although the best strategy for achieving this is still controversial.

CONCLUSION

Following PCI, CI-AKI is an overlooked complication which is associated with significant morbidity and mortality. In this article, we review the pathophysiology of CI-AKI in patients undergoing PCI and discuss the potential therapeutic options for preventing it.

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.

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.

Meta-analysis: serum creatinine changes following contrast enhanced CT imaging

PURPOSE

Contrast induced nephropathy (CIN) is defined as a decrease in renal function following administration of contrast media. The aim of this meta-analysis was to asses the overall risk of CIN, chronic loss of kidney function and the need for renal replacement therapy (RRT) after intravenous contrast enhanced CT-scan. Secondly, we aimed to identify subgroups at increased risk for CIN.

MATERIALS AND METHODS

A literature search in Pubmed, Medline, Embase and Cochrane databases was performed. Data extraction was carried out independently by two reviewers. Meta-analysis and meta-regression were performed using an exact likelihood approach.

RESULTS

Forty studies evaluating the incidence of CIN after CT were included. The pooled incidence of CIN was 6.4% (95% CI 5.0-8.1). The risk of RRT after CIN was low, 0.06% (95% CI 0.01-0.4). The decline in renal function persisted in 1.1% of patients (95% CI 0.6-2.1%). Patients with chronic kidney disease (odds ratio 2.26, p<0.001) or diabetes mellitus (odds ratio 3.10, p<0.001) were at increased risk for the development of CIN.

CONCLUSION

CIN occurred in 6% of patients after contrast enhanced CT. In 1% of all patients undergoing contrast enhanced CT the decline in renal function persisted.

Impact on renal function of percutaneous thermal ablation of renal masses in patients with preexisting chronic kidney disease

PURPOSE

To examine the effect of percutaneous thermal ablation of renal masses on renal function among patients with baseline chronic kidney disease (CKD).

MATERIALS AND METHODS

Patients with baseline CKD (initial glomerular filtration rate [GFR] < 60 mL/min/1.73 m(2)) who underwent percutaneous cryoablation or radiofrequency (RF) ablation of renal masses were reviewed.

RESULTS

A total of 48 patients with a GRF of 60 mL/min/1.73 m(2) or lower were treated with renal cryoablation or RF ablation and had follow-up GFR measurement 1 month afterward. Mean patient age was 73 years (range, 47-89 y). Cryoablation was performed in 22 patients and RF ablation was performed in 26. Mean tumor diameter was 3.4 cm (range, 0.9-10.2 cm). Mean overall GFRs were 39.8 mL/min/1.73 m(2) at baseline and 39.7 mL/min/1.73 m(2) at 1 month after ablation (P = .85). A total of 38 patients had 1-year follow-up GFR measurement (cryoablation, n = 18; RF ablation, n = 20), and their mean GFR was 40.9 mL/min/1.73 m(2) ± 11.4 (SD), compared with a preablation GFR of 41.2 mL/min/1.73 m(2)(P = .79). In the cryoablation group, mean GFRs at 1 month and 1 year were 41.4 mL/min/1.73 m(2) and 44.4 mL/min/1.73 m(2), compared with respective baseline GFRs of 41.1 mL/min/1.73 m(2) and 42.1 mL/min/1.73 m(2) (P = .75 and P = .19, respectively). In the RF ablation group, mean GFRs at 1 month and 1 year were 38.2 mL/min/1.73 m(2) and 37.8 mL/min/1.73 m(2), compared with respective baseline GFRs of 38.7 mL/min/1.73 m(2) and 40.4 mL/min/1.73 m(2) (P = .58 and P = .09, respectively).

CONCLUSIONS

Independent of ablation modality, percutaneous renal mass ablation does not appear to affect renal function among patients with CKD.

Contrast induced nephropathy: updated ESUR Contrast Media Safety Committee guidelines

PURPOSE

The Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) has updated its 1999 guidelines on contrast medium-induced nephropathy (CIN).

AREAS COVERED

Topics reviewed include the definition of CIN, the choice of contrast medium, the prophylactic measures used to reduce the incidence of CIN, and the management of patients receiving metformin. Key Points • Definition, risk factors and prevention of contrast medium induced nephropathy are reviewed. • CIN risk is lower with intravenous than intra-arterial iodinated contrast medium. • eGFR of 45 ml/min/1.73 m (2) is CIN risk threshold for intravenous contrast medium. • Hydration with either saline or sodium bicarbonate reduces CIN incidence. • Patients with eGFR ≥ 60 ml/min/1.73 m (2) receiving contrast medium can continue metformin normally.

No increased risk for contrast-induced nephropathy after multiple CT perfusion studies of the brain with a nonionic, dimeric, iso-osmolal contrast medium

BACKGROUND AND PURPOSE

Contrast-induced nephropathy (CIN) is one of the most common causes of in-hospital acute renal failure. The aim of this study was to assess the risk for CIN after repeated administration of the nonionic, dimeric, iso-osmolal contrast agent iodixanol regardless of pre-existing renal function. Changes in serum creatinine (SCr) levels were compared with those of control subjects who did not receive iodinated contrast media (CM).

MATERIALS AND METHODS

Between January 2005 and March 2007, a total of 100 consecutive patients were prospectively included. Patients underwent a CT perfusion (CTP) study of the brain from clinical signs of acute cerebral infarction. CTP was performed with an intravenous bolus of 60 mL of iodixanol-270. Precontrast and postcontrast SCr levels were obtained, and the CTP study was repeated within 32 hours and postcontrast SCR was assessed. The control group consisted of 100 patients scheduled for plain cranial CT examination, who were not exposed to iodinated CM.

RESULTS

Mean baseline SCr level was 0.96 +/- 0.35 mg/dL in the contrast group and 1.14 +/- 0.74 mg/dL in the control group. After repeated administration of CM, a total of 7 patients had a relative increase of greater than or equal to 25% compared with baseline. In the control group, a relative increase of 25% or more was seen in 12 patients. The difference in the incidence of the rise in SCr of >25% was not significantly different (P = .094).

CONCLUSION

Multiple contrast-enhanced studies with intravenously administered iodixanol are not associated with a higher risk for CIN compared with a control group receiving no CM.

Renal artery stenosis in chronic renal failure: caution is advised for percutaneous revascularization

INTRODUCTION

Percutaneous intervention for renal artery stenosis may lead to acute deterioration of renal function and, consequently, of a patient's well-being. The purpose of this study was to determine whether selection by indication for renal artery stenosis was predictive of outcome.

METHODS

All patients who underwent intervention for renal artery stenosis were selected to participate in the study and their indication for intervention was determined. Patient characteristics, i.e., renal function and clearance by modified diet in renal disease (MDRD), blood pressure and its treatment, kidney size, proteinuria, and cardiovascular events, were recorded before intervention, at 1 year, and at the end of follow-up. An intervention was classified as a success, no change, or a failure with respect to the indication for intervention. Successful interventions were compared to failures with respect to indication and patient characteristics.

RESULTS

Twenty-four patients were included in the study: 11 for renal failure (RF), 9 for hypertension (HT), and 4 due to flash pulmonary edema (FPE). One patient with RF, four with HT, and one with FPE benefited from intervention. Nine patients with RF and two with HT were classified as failures. Failure was most prevalent in the RF group (p<0.05). Other predictors of failure were older age (p<0.02), worse renal function (p<0.02), smaller kidneys (p<0.03), and previous cardiovascular events (p<0.05).

CONCLUSIONS

Renal failure must be considered a contraindication for intervention in renal artery stenosis. Intervention can be considered in FPE and hypertension, provided other predictive factors for failure are absent.

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.

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.

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.

Contrast medium use

Various properties of iodinated contrast media (osmolality, ionic versus nonionic, and viscosity) may contribute to contrast-induced nephropathy (CIN). Therefore, the choice of contrast medium affects the risk for CIN. There is good evidence that low-osmolar contrast media are less nephrotoxic than high-osmolar contrast media in patients at increased risk for CIN who receive intra-arterial iodinated contrast. Current evidence suggests that nonionic isosmolar contrast presents the lowest risk for CIN in patients with chronic kidney disease (CKD), particularly in those patients with diabetes mellitus. Intra-arterial administration of contrast media may be associated with a greater risk for CIN above that observed with intravenous administration. The use of gadolinium or CO(2) as alternative contrast media to avoid the risk of nephrotoxicity cannot be substantiated by clinical trials and therefore cannot be recommended. Most studies show that, within a class, higher volumes (>100 mL) of iodinated contrast medium are associated with a higher risk for CIN. However, in patients at high risk, such as those with CKD and diabetes, even small volumes of contrast medium can have adverse effects on renal function.

Risk of Nephropathy after Intravenous Administration of Contrast Material: A Critical Literature Analysis

PURPOSE

To assess the risk of nephropathy after administration of contrast material by reviewing the published literature on intravenous contrast material administration and by separating reports with appropriate control measures from those without such measures.

MATERIALS AND METHODS

The MEDLINE database was searched for articles published from October 1966 to September 2004 that contained the phrases "contrast," "contrast medium," "contrast media," or "radiocontrast" and any of the words or phrases "nephrotoxicity," "nephropathy," kidney failure," or "renal failure." The identified publications were reviewed and limited to original clinical series. Studies were categorized according to the route of contrast material administration. Those in which an identifiable group of patients received contrast material intravenously were further evaluated to determine which studies compared results with those from a control group of patients who did not receive contrast material.

RESULTS

Only 40 (1.3%) of 3081 publications had patients who received contrast material intravenously. Of these, only two publications had control groups of patients who received no contrast material. The incidence of postcontrast nephropathy in these two series was not substantially different from that in the control groups.

CONCLUSION

Properly controlled clinical studies of intravenously administered radiographic contrast media fail to demonstrate renal damage.

Outcomes of contrast-induced nephropathy: Experience in patients undergoing cardiovascular intervention

Use of iodinated contrast media for diagnostic and interventional procedures is increasing as computed tomography and percutaneous coronary intervention (PCI) technologies provide increasing patient benefit. Although some complications associated with contrast media are mild and transient, contrast-induced nephropathy (CIN) can negatively affect long-term patient morbidity and mortality. The incidence of and outcomes from CIN have been carefully studied in cardiology patients. A number of studies have identified CIN-associated complications in PCI patients, including bleeding, hematoma, stroke, adult respiratory distress syndrome, electrolyte imbalances, and sepsis. In post-PCI patients, rates of myocardial infarction and vessel reocclusion are more common in patients with CIN. Therefore, in-hospital mortality is increased in patients with CIN. In patients requiring dialysis after PCI, several studies have shown the 1-year mortality rate to be >55%. Even moderate renal dysfunction not requiring dialysis is associated with increased mortality in patients with coronary artery disease. Precautionary measures before, during, and after the use of contrast media that reduce the incidence of CIN, such as discontinuation of nephrotoxic medications, adequate hydration, and use of appropriate volumes and types of contrast media, should be considered in all patients with renal insufficiency or with other risk factors for CIN.

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.

The Clinical Epidemiology of Contrast-Induced Nephropathy

Recent improvements in contrast agents and radiologic imaging tools have resulted in an increasing number of patients undergoing contrast media (CM)-enhanced examinations. Although the majority of patients undergoing these diagnostic and therapeutic procedures experience only mild adverse events, some patient subpopulations are at risk for developing contrast-induced nephropathy (CIN), an adverse event that is associated with high morbidity and mortality. Contrast-induced nephropathy is usually defined as an increase of > or =25% in the serum creatinine level relative to baseline. Pathophysiologic mechanisms underlying this disorder are not fully understood, but it is currently believed that disturbances in renal hemodynamics and a direct effect of CM on renal tubules are involved. In the general population, the incidence of CIN is estimated to be 1% to 6%. However, the risk may be as high as 50% in some patient subgroups. Patients with diabetes and pre-existing renal impairment are at high risk, and CIN incidence increases in patients with multiple comorbidities. The volume and osmolality of CM used also play a role in the development of CIN. Patients who develop CIN are more likely to die in-hospital and, for those who are discharged, 1-year mortality rates are high. Whether this is due to CM, comorbidity, or concurrent comorbid events is unclear. Randomized controlled trials that measure non-renal clinical outcomes are necessary to determine whether interventions that prevent CIN can also prevent non-renal adverse events. A review of the incidence, pathogenesis, and clinical consequences of CIN is provided.