Nephrotoxic effects in high-risk patients undergoing angiography

Extended renal outcomes with use of iodixanol versus iohexol after coronary angiography

The impact of isoosmolar versus low-osmolar contrast media (CM) administration on contrast-induced acute kidney injury (CI-AKI) and extended renal dysfunction (ERD) is unclear. We retrospectively examined incidences of CI-AKI and ERD in patients who received iodixanol (isoosmolar) versus iohexol (low-osmolar) during angiography for cardiac indications. Of 713 patients, 560 (cohort A), 190 (cohort B), and 172 (cohort C) had serum creatinine monitored at 3 days, 30 days, and 6 months after angiography, respectively. 18% of cohort A developed CI-AKI, which was more common with iodixanol than iohexol (22% versus 13%, P = 0.006). However, patients given iodixanol were older with lower baseline estimated glomerular filtration rates (eGFR). On multivariate analysis, independent associations with higher CI-AKI risk include age >65 years, female gender, cardiac failure, ST-elevation myocardial infarction, intra-aortic balloon pump, and critical illness, but not CM type, higher CM load, or eGFR < 45 mL/min/1.73 m². 32% of cohort B and 34% of cohort C had ERD at 30 days and 6 months, while 44% and 41% of subcohorts had ERD at 90 days and 1 year, respectively. CI-AKI, but not CM type, was associated with medium- and longer-term ERD, with 3-fold higher risk. Advanced age, emergent cardiac conditions, and critical illness are stronger predictors of CI-AKI, compared with CM-related factors. CI-AKI predicts longer-term ERD.

Estimation of glomerular filtration rate in cynomolgus monkeys (Macaca fascicularis)

To estimate the glomerular filtration rate (GFR) in cynomolgus monkeys (Macaca fascicularis), a three-blood-sample method using iodixanol was assessed in comparison with the conventional multisample strategy using inulin. Iodixanol and inulin were coadministered intravenously 40 mg I/kg and 50 mg/kg, respectively, to male monkeys, followed by blood collection 60, 90 and 120 min later. A close correlation (r=0.96) was noted between the GFR values estimated by both methods. In clinically healthy monkeys, the basal values were determined to be 3.06 ± 0.50 ml/min/kg. This is the first report, suggesting that serum clearance of iodixanol is a ready-to-use tool for a screening the GFR in monkeys, although it is necessary to perform a more longitudinal study using animals with reduced renal function.

Relative Nephrotoxicity of Different Contrast Media

Contrast-induced nephropathy (CIN) is a common cause of acute kidney injury among hospitalized patients. High-osmolar contrast agents are associated with increased risk of CIN. Low-osmolar (LOCM) and iso-osmolar (IOCM) agents show no difference in the incidence of CIN, even among high-risk patients. This finding suggests that factors other than osmolality may play a role in the pathogenesis of CIN. The use of either LOCM or IOCM agents is recommended in high-risk patients.

A Practical Approach to Preventing Renal Complications in the Catheterization Laboratory

Kidney injury following cardiac catheterization is an infrequent, though persistent, complication, which in some cases may be preventable. Patients at increased risk for renal complications following catheterization can be identified through individual and procedural risk factors, and several risk-prediction models are readily available. The authors advocate for the development of an easily implemented and standardized protocol, readily accessible to catheterization laboratory staff, for the identification and treatment of those patients who may be at increased risk for renal complications following cardiac catheterization.

Renal Complications in Patients Undergoing Peripheral Artery Interventions

Surgical or endovascular revascularization procedures for severe peripheral artery disease (PAD) are typically performed in patients with lifestyle-limiting symptoms or evidence of end-organ ischemia secondary to PAD. The role of endovascular therapy in the treatment of PAD is expanding. Contrast-induced nephropathy is the most important and most frequent renal complication of endovascular interventional procedures. Knowledge about complications and their prevention and management is essential for successful outcomes. This article focuses on renal complications during peripheral artery interventions.

Renal protection: preconditioning for the prevention of contrast-induced nephropathy

As the numbers of interventional procedures are rising exponentially, identification of those patients at risk for renal complications has become even more important. Renal complications have been associated with increased morbidity and mortality after interventions. Risk factors have been studied to help identify those patients at increased risk for developing contrast-induced nephropathy. Hydration and medications have been studied as protective measures to decrease risk of renal complications. Preconditioning patients with intravenous hydration has been found to be the most helpful in circumventing postprocedural contrast-induced nephropathy.

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.

Side effects of radiographic contrast media: pathogenesis, risk factors, and prevention

Radiocontrast media (RCM) are medical drugs used to improve the visibility of internal organs and structures in X-ray based imaging techniques. They may have side effects ranging from itching to a life-threatening emergency, known as contrast-induced nephropathy (CIN). We define CIN as acute renal failure occurring within 24-72 hrs of exposure to RCM that cannot be attributed to other causes. It usually occurs in patients with preexisting renal impairment and diabetes. The mechanisms underlying CIN include reduction in medullary blood flow leading to hypoxia and direct tubule cell damage and the formation of reactive oxygen species. Identification of patients at high risk for CIN is important. We have reviewed the risk factors and procedures for prevention, providing a long list of references enabling readers a deep evaluation of them both. The first rule to follow in patients at risk of CIN undergoing radiographic procedure is monitoring renal function by measuring serum creatinine and calculating the eGFR before and once daily for 5 days after the procedure. It is advised to discontinue potentially nephrotoxic medications, to choose radiocontrast media at lowest dosage, and to encourage oral or intravenous hydration. In high-risk patients N-acetylcysteine may also be given.

Ascorbic Acid for the prevention of contrast-induced nephropathy after coronary angiography in patients with chronic renal impairment: a randomized controlled trial

To determine the incidence of contrast-induced nephropathy (CIN) and to assess the effectiveness of ascorbic acid in the prevention of CIN after coronary angiography in patients with chronic renal impairment. CIN is the third most common cause of hospital-acquired renal failure. It is well documented that periprocedural hydration is effective in the prevention of CIN. Little data exist on the effectiveness of ascorbic acid, a vitamin with antioxidative action. Patients with stable serum creatinine level >107 μmol/L (n = 81) undergoing coronary angiography were randomized to receive either ascorbic acid (N = 40) or placebo (N = 41) before the procedure. All patients received intravenous volume expansion with normal saline before the procedure. CIN was defined as an increase of serum creatinine level >25% from baseline measured 3 to 4 days after the procedure. CIN occurred totally in 5/81 patients (6.2%); in two patients (3%) in the ascorbic acid group and in three patients (7.3%) in the placebo group (P = 0.512). Postprocedural worsening of renal function (postprocedural increase of serum creatinine level) was present in 10/81 patients (12.3%) in the ascorbic acid group and in 19/81 patients (23.4%) in the placebo group (P = 0.038). No patient required dialysis treatment. We found no statistically significant impact of ascorbic acid on the incidence of CIN in patients with chronic renal impairment undergoing coronary arteriography or angioplasty. Ascorbic acid may still have some protective role in CIN reflected in lower incidence of worsening of renal function in the treated group.

Antioxidant effect of Phyllanthus emblica extract prevents contrast-induced acute kidney injury

Background

Contrast-induced acute kidney injury (CI-AKI) occurs after the administration of intravenous iodinated contrast agents. Oxidative stress has been proposed as one of the most important mechanisms in the pathogenesis of CI-AKI. The objective of this study was to investigate the antioxidant effect of the extract from Phyllanthus emblica (PE) in preventing CI-AKI.

Methods

Male Sprague Dawley rats were subjected into eight groups, were given water (control) or PE extract (125 or 250 or 500 mg/kg/day) for 5 days before the induction of CI-AKI. Renal function and oxidative stress markers; malondialdehyde (MDA), total antioxidant capacity (TAC), superoxide dismutase (SOD) and catalase (CAT) activity were determined in plasma and renal tissue. Kidney sections were performed for histopathological examination.

Results

In the contrast media (CM) group, increases in blood urea nitrogen and serum creatinine were demonstrated which correlated with severity of tubular necrosis, peritubular capillary congestion and interstitial edema. Moreover, an increase in MDA and a decrease in TAC SOD and CAT activity in CM group were significantly changed when compared with the control (P < 0.05). In contrast, CI-AKI-induced rats administrated with PE extract 250 and 500 mg/kg/day significantly preserved renal function and attenuated the severity of pathological damage (P < 0.05) as well as significantly lower MDA and higher TAC, SOD and CAT than the CM group (P < 0.05).

Conclusions

This study demonstrated the protective role of PE extract against CI-AKI.

Contrast-induced nephropathy; A literature review

CONTEXT

Contrast-induced nephropathy (CIN) is a common cause of acute kidney dysfunction.

EVIDENCE ACQUISITIONS

Directory of Open Access Journals, Google Scholar, PubMed, EBSCO and Web of Science have been searched.

RESULTS

It is necessary to identify at risk patients at early stages to implement preventive strategies to decrease the incidence of this nephropathy. However, mechanisms of CIN have not fully explained yet. It seems that mechanisms which mediated by nitric oxide and prostaglandin-induced vasodilatation have been played a crucial role in the CIN. Hemodynamic changes of renal blood flow, which causes hypoxia in the renal medulla and direct toxic effects of contrast media on renal cells, are thought to contribute to the pathogenesis of CIN. Contrast media is normally divided into iso-osmolar, low-osmolar, and high-osmolar. N-acetylcysteine is considered as one of the best choices to prevent CIN in high-risk groups.

CONCLUSIONS

The first aim to prevent CIN is identifying high-risk subjects and controlling associate risk factors. As significant differences existed between contrasts agents due to their physicochemical properties, low-osmolar or iso-osmolar contrast media should be used to prevent CIN in at-risk patients. The volume of contrast media should be as low as possible.

Is contrast medium osmolality a causal factor for contrast-induced nephropathy?

The exact pathophysiology of contrast-induced nephropathy (CIN) is not fully clarified, yet the osmotic characteristics of contrast media (CM) have been a significant focus in many investigations of CIN. Osmotic effects of CM specific to the kidney include transient decreases in blood flow, filtration fraction, and glomerular filtration rate. Potentially significant secondary effects include an osmotically induced diuresis with a concomitant dehydrating effect. Clinical experiences that have compared the occurrence of CIN between the various classes of CM based on osmolality have suggested a much less than anticipated advantage, if any, with a lower osmolality. Recent animal experiments actually suggest that induction of a mild osmotic diuresis in association with iso-osmolar agents tends to offset potentially deleterious renal effects of high viscosity-mediated intratubular CM stagnation.

Exposure to low- vs iso-osmolar contrast agents reduces NADPH-dependent reactive oxygen species generation in a cellular model of renal injury

Contrast-induced nephropathy represents the third cause of hospital-acquired acute renal failure. This study investigated the effects of low- vs iso-osmolar contrast medium (CM) exposure on NADPH-dependent reactive oxygen species (ROS) generation by tubular cells. X-ray attenuation of iohexol, iopamidol, and iodixanol was assessed at equimolar iodine concentrations and their effects on human renal proximal tubular cells (PTCs) were evaluated with equally attenuating solutions of each CM. Cytotoxicity, apoptosis, and necrosis were investigated by trypan blue exclusion, MTT assay, and annexin V/propidium iodide assay, respectively. ROS production was assessed by DCF assay, NADPH oxidase activity by the lucigenin-enhanced chemiluminescence method, and Nox4 expression by immunoblot. Yielding the same X-ray attenuation, CM cytotoxicity was assessed in PTCs at equimolar iodine concentrations. More necrosis was present after incubation with iohexol and iopamidol than after incubation with equal concentrations of iodixanol. Iohexol and iodixanol at low iodine concentrations induced less cytotoxicity than iopamidol. Moreover, both iohexol and iopamidol induced more apoptosis than iodixanol, with a dose-dependent effect. ROS generation was significantly higher with iopamidol and iohexol compared to iodixanol. NADPH oxidase activity and Nox4 protein expression significantly increased after exposure to iopamidol and iohexol, with a dose-dependent effect, compared with iodixanol. CM-induced Nox4 expression and activity depended upon Src activation. In conclusion, at angiographic concentrations, iodixanol induces fewer cytotoxic effects on cultured tubular cells than iohexol and iopamidol along with a lower induction of Nox4-dependent ROS generation. This enzyme may, thus, represent a potential therapeutic target to prevent iodinated CM-related oxidative stress.

Percutaneous coronary intervention in treatment of multivessel coronary artery disease in patients with non-ST-segment elevation acute coronary syndrome

Among patients with non-ST-elevated acute coronary syndromes (NSTE-ACS) the estimated percentage of single vessel coronary artery disease (SV-CAD) observed during coronarography is about 20-40%, while multivessel coronary artery disease (MV-CAD) is found in about 40-60%. Further treatment in patients with both SV CAD and MV CAD is usually culprit vessel percutaneous coronary intervention (CV-PCI). Nevertheless, in the group of patients with MV-CAD there is still a problematic decision whether the non-infarct related arteries (non-IRA) should be treated with PCI. According to the European Society of Cardiology (ESC) guidelines on myocardial revascularization this decision should be based on the overall clinical and angiographic status of the patient; simultaneously they suggest performing ad hoc CV-PCI. The decision of performing intervention in the rest of the narrowed coronary arteries should be made after consultation with the heart team or according to the protocols adopted in the specific clinic. Furthermore, there is a question of whether the procedure should be performed immediately after culprit vessel revascularization or it should be postponed until the patient is stabilized. Due to the lack of specific recommendations we decided to perform an analysis of existing studies which compared culprit versus multivessel revascularization in patients with MV-CAD and non-ST-elevated acute coronary syndromes.

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.

Canadian Association of Radiologists consensus guidelines for the prevention of contrast-induced nephropathy: update 2012

PURPOSE

Contrast-induced acute kidney injury or contrast-induced nephropathy (CIN) is a significant complication of intravascular contrast medium (CM). These guidelines are intended as a practical approach to risk stratification and prevention. The major risk factor that predicts CIN is pre-existing chronic kidney disease.

METHODS

Members of the committee represent radiologists and nephrologists across Canada. The previous guidelines were reviewed, and an in-depth up-to-date literature review was carried out.

RESULTS

A serum creatinine level (SCr) should be obtained, and an estimated glomerular filtration rate (eGFR) should be calculated within 6 months in the outpatient who is stable and within 1 week for inpatients and patients who are not stable. Patients with an eGFR of ≥ 60 mL/min have an extremely low risk of CIN. The risk of CIN after intra-arterial CM administration appears be at least twice that after intravenous administration. Fluid volume loading remains the single most important measure, and hydration regimens that use sodium bicarbonate or normal saline solution should be considered for all patients with GFR < 60 mL/min who receive intra-arterial contrast and when GFR < 45 mL/min in patients who receive intravenous contrast. Patients are most at risk for CIN when eGFR < 30 mL/min. Additional preventative measures include the following: avoid dehydration, avoid CM when appropriate, minimize CM volume and frequency, avoid high osmolar CM, and discontinue nephrotoxic medications 48 hours before administration of CM.

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.

ECONOMIC EVALUATION OF INTRAVENOUS IODINATED CONTRAST MEDIA IN ITALY

Background: Contrast-induced acute kidney injury (CI-AKI) is defined as a deterioration in renal function after administration of radiologic iodinated contrast media (CM). Iodixanol, showed a lower CI-AKI incidence than low-osmolar contrast media (LOCM). A cost-effectiveness analysis was performed comparing iodixanol and LOCM in intravenous (IV) setting in Italy.

Methods: A Markov model was developed. Patients moved across four health states: CI-AKI free, CI-AKI, myocardial infarction, and death. The simulation horizon was lifetime with 1-month cycles. Costs and outcomes were discounted at 3.5 percent rate. CI-AKI incidence was considered from published literature across different definitions. Cost-effectiveness of iodixanol was assessed in terms of incremental cost per life-year gained. Net monetary benefit (NMB) was also calculated. Both deterministic and probabilistic sensitivity analyses were performed.

Results: Base-case results showed an average survival increase of 0.51 life-years and a savings of €7.25 for iodixanol versus LOCM. The cost-effectiveness of iodixanol was confirmed when other scenarios were explored, such as varying CI-AKI definition, sub-populations with specified risk factors, CM hospital bids prices, and inclusion of adverse drug reactions of allergic nature. An NMB ranging between €6,007.25 and €30,007.25 was calculated.

Conclusion: Base-case results show that IV iodixanol is cost-effective compared with LOCM in the Italian clinical setting of a hospital computed tomography radiology practice. However, some caution is due, mainly linked to inherent limitations of the modeling technique and to the lack of agreement on CI-AKI incidence data in the clinical literature.

Contrast-induced nephropathy in aged critically ill patients

Background. Aging is associated with renal structural changes and functional decline. The attributable risk for renal dysfunction from radiocontrast agents in critically ill older patients has not been well established. Methods. In this prospective study, we assessed the incidence of contrast-induced nephropathy (CIN) in critically ill patients with stable renal function who underwent computed tomography with intravenous contrast media. Patients were categorized into two age groups: <65 (YG) or ≥65 years old (OG). CIN was defined as 25% or greater increase from baseline of serum creatinine or as an absolute increase by 0.5 mg/dL until the 5th day after the infusion of contrast agent. We also evaluated the alterations in oxidative stress by assessing serum 8-isoprostane. Results. CIN occurred in 5 of 13 OG patients (38.46%) whereas no YG patient presented CIN (P = 0.015). Serum creatinine kinetics in older patients demonstrated a rise over five days following contrast infusion time while a decline was observed in the YG (P = 0.005). Conclusions. Older critically ill patients are more prone to develop renal dysfunction after the intravenous infusion of contrast agent in relation to their younger counterparts.

Nephropathy after administration of iso-osmolar and low-osmolar contrast media: evidence from a network meta-analysis

BACKGROUND/OBJECTIVES

Contrast-induced nephropathy (CIN) may be a severe complication to the administration of iodine-based contrast media for diagnostic or interventional procedure using radiation exposure. Whether there is a difference in nephrotoxic potential between the various agents is uncertain. We aimed to perform a systematic review and network meta-analysis of randomized trials on iodine-based contrast agents.

METHODS

Randomized trials of low-osmolar or iso-osmolar contrast media were searched in CENTRAL, Google Scholar, MEDLINE/PubMed, and Scopus. Risk of CIN was appraised within a hierarchical Bayesian model computing absolute rates (AR) and odds ratios (OR) with 95% credibility intervals, and probability of being best (Pbest) for each agent.

RESULTS

A total of 42 trials (10048 patients) were included focusing on 7 different iodine-based contrast media. Risk of CIN was similarly low with iodixanol (AR=5.7% [2.2%-13.9%], Pbest=18.8%), iomeprol (AR=6.0% [2.2%-15.4%], Pbest=24.8%), iopamidol (AR=6.1% [2.2%-15.5%], Pbest=21.5%), and ioversol (AR=6.0% [2.1%-16.4%], Pbest=31.3%). Conversely, CIN was twice as common with iohexol (AR=11.2% [4.1%-29.5%], Pbest=0.1%) and ioxaglate (AR=11.0% [4.0%-26.9%], Pbest<0.1%), with both proving less safe than iodixanol (respectively OR=2.18 [1.22-3.92] and 2.05 [1.26-3.29]), iomeprol (OR=2.08 [1.04-4.17] and 1.96 [1.06-3.48]) and iopamidol (OR=2.04 [1.15-3.85] and 1.92 [1.06-3.45]). Data on iopromide were less conclusive (AR=6.9% [2.6%-17.1%], Pbest=3.6%).

CONCLUSIONS

Iodixanol, iomeprol, iopamidol and ioversol are iodine-based contrast media with a similar renal safety profile. Iohexol and ioxaglate have a poorer renal safety profile, whereas further data may be required on iopromide.

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

BACKGROUND

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

PURPOSE

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

METHOD

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

RESULTS

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

CONCLUSION

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

CLINICAL IMPLICATIONS

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

Contrast media: are there differences in nephrotoxicity among contrast media?

Iodinated contrast agents are usually classified based upon their osmolality--high, low, and isosmolar. Iodinated contrast agents are also nephrotoxic in some but not all patients resulting in loss of glomerular filtration rate. Over the past 30 years, nephrotoxicity has been linked to osmolality although the precise mechanism underlying such a link has been elusive. Improvements in our understanding of the pathogenesis of nephrotoxicity and prospective randomized clinical trials have attempted to further explore the relationship between osmolality and nephrotoxicity. In this review, the basis for our current understanding that there are little if any differences in nephrotoxic potential between low and isosmolar contrast media will be detailed using data from clinical studies.

Imaging diagnosis of acute pulmonary embolism

Pulmonary embolism represents a major public healthcare problem and it also imposes frequent clinical diagnostic issues. Despite the availability of the D-dimer tests, imaging remains the mainstay for its diagnosis. Computed tomography pulmonary angiography (CTPA) is now the most widely used diagnostic test and its utility has been well validated in a large number of trials. Nuclear medicine techniques, which are also well established, are now used significantly less frequently. Magnetic resonance pulmonary angiography is developing as an alternative to CTPA in patients who have contraindications to iodinated contrast media. Catheter pulmonary angiography remains the gold standard, although it is being used increasingly less frequently. In this article, we review the current knowledge on the imaging diagnosis of acute pulmonary embolism with special emphasis on the noninvasive techniques.

Renal safety of iodixanol

Iodinated contrast is a mainstay for diagnostic and interventional procedures performed by cardiologists, radiologists and other specialists. With the emergence of computed tomographic techniques for the evaluation of cardiac disease, malignancies, trauma and a variety of other internal disorders, the use of iodinated contrast is expected to increase dramatically over the next few years. There has been considerable refinement over the past decades from ionic high-osmolar, to nonionic low-osmolar and finally to nonionic iso-osmolar contrast. Iodixanol is the only nonionic iso-osmolar contrast approved for intravascular use. This contrast agent has the lowest rates of systemic and renal adverse events. Clinical trials have demonstrated the lowest rates of contrast-induced nephropathy among all currently available forms of iodinated contrast. Specifically, iodixanol has been associated with a 71% relative risk reduction for contrast-induced nephropathy compared with low-osmolar agents in head-to-head randomized trials. This article reviews the structure, pharmacology and outcomes associated with iodixanol.

Complications of neuroimaging

Modern imaging techniques with computed tomography (CT) and magnetic resonance imaging (MRI) have revolutionized neuroimaging. While eliminating the risks of invasive procedures, new risks must now be considered before ordering neuroimaging. Advanced imaging techniques with CT may pose a risk of significant radiation exposure. Contrast may pose a risk in patients with pre-existing renal failure. MR is associated with risks related to the static magnetic field, to risks associated with the magnetic field gradients, and to risk from contrast media. Neurointervenional techniques allow for nonoperative treatment of a variety of intracranial and spinal pathologies, but with associated risks of embolization, radiation exposure, bleeding complications at the access site and a potential for contrast-related nephropathy.

Comparison of the safety of seven iodinated contrast media

We aimed to determine the characteristic adverse events (AEs) of iodinated contrast media (IOCM) and to compare the safety profiles of different IOCM. This study used the database of AEs reports submitted by healthcare professionals from 15 Regional Pharmacovigilance Centers between June 24, 2009 and December 31, 2010 in Korea. All reports of IOCM, including iopromide, iohexol, iopamidol, iomeprol, ioversol, iobitridol and iodixanol, were analyzed. Safety profiles were compared between different IOCM at the system organ level using the proportional reporting ratio (PRR) and 95% confidence interval (95% CI). Among a total of 48,261 reports, 6,524 (13.5%) reports were related to the use of IOCM. Iopromide (45.5%), iohexol (16.9%), iopamidol (14.3%) and iomeprol (10.3%) were identified as frequently reported media. 'Platelet, bleeding & clotting disorders' (PRR, 29.6; 95%CI, 1.9-472.6) and 'urinary system disorders' (PRR, 22.3; 95% CI, 17.1-29.1) were more frequently reported for iodixanol than the other IOCM. In conclusion, the frequency of AEs by organ class was significantly different between individual media. These differences among different IOCM should be considered when selecting a medium among various IOCM and when monitoring patients during and after its use to ensure optimum usage and patient safety.

Contrast-induced nephropathy in critical care

Contrast-induced nephropathy is an iatrogenic disease caused by the administration of iodinated contrast material to certain at-risk patients. The clinical features include renal failure, with oliguria, anuria, and electrolyte derangements. Contrast-induced nephropathy can prolong hospitalization, result in greater morbidity and mortality, and increase patients' costs. A variety of preventive and treatment strategies exist, including use of alternative imaging. Critical care nurses need to understand the nephropathy and the patients at risk and to develop a familiarity with prevention, treatment, and outcome.

Radiographic contrast-media-induced acute kidney injury: pathophysiology and prophylactic strategies

Contrast-induced acute kidney injury (CI-AKI) is one of the most widely discussed and debated topics in cardiovascular medicine. With increasing number of contrast-media- (CM-) enhanced imaging studies being performed and growing octogenarian population with significant comorbidities, incidence of CI-AKI remains high. In this review, pathophysiology of CI-AKI, its relationship with different types of CM, role of serum and urinary biomarkers for diagnosing CI-AKI, and various prophylactic strategies used for nephroprotection against CI-AKI are discussed in detail.

Intravascular radiocontrast iodixanol increases permeability of proximal tubule epithelium: a possible mechanism of contrast-induced nephropathy

PURPOSE

To investigate the effect of Iodixanol on kidney proximal tubular cell line human kidney 2 (HK-2).

METHODS

The HK-2 cells were treated with Iodixanol. A Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay was used to evaluate apoptosis. Cell viability was measured by proliferation assay kit. Cell permeability changes were assessed by transwell assay and intercellular gaps measurement. Expression of claudin-2 was assessed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and Western blot.

RESULTS

Iodixanol reduced tubule cell viability (P < .01) but did not cause apoptosis. The intercellular gap formation (P < .01) and transwell (P < .05) assays revealed that cell permeability significantly increased after Iodixanol treatment of monolayer cells. Western blot and qRT-PCR showed significant upregulation of claudin-2 protein (P < .05) and messenger RNA expression (P < .01).

CONCLUSIONS

Our in vitro data do not support the hypothesis that direct kidney cell death from Iodixanol is a major mechanism of contrast-induced nephropathy (CIN). However, increased permeability of proximal tubule epithelium caused by Iodixanol may play an important role in CIN.

The effect of L-carnitine on oxidative stress responses of experimental contrast-induced nephropathy in rats

This study was conducted to investigate the prophylactic effects of carnitine against contrast-induced nephropathy (CIN) and its relation to oxidant/antioxidant status in kidney, liver, heart, spleen and lung tissues in a CIN rat model. Twenty-eight adult male Wistar rats were divided into 4 groups, the control, contrast media (CM), carnitine and contrast media+carnitine (CM+carnitine) groups. Animals were placed in individual metabolism cages, and on the 2nd day, rats were deprived of water for 24 hr. On the 3rd day, contrast media were administered to groups CM and CM+carnitine. L-carnitine was administered on days 2, 3 and 4. Histopathological changes were evaluated in the right kidney after euthanization. Superoxide dismutase (SOD) and catalase (CAT) activities and glutathione (GSH) and malondialdehyde (MDA) levels were measured in renal, liver, heart, spleen and lung tissues. The SOD activities in the renal (P<0.05), liver (P<0.001) and spleen (P<0.05) tissues were increased in the carnitine group. The CAT activities in the spleen tissue were decreased (P<0.01) only in the CM group. Renal (P<0.05), liver (P<0.001), spleen (P<0.001) and lung tissue (P<0.01) GSH levels were found to be higher in the carnitine group. In renal, liver and lung tissues, the MDA levels increased in the CM group (P<0.001). The histopathological findings showed that L-carnitine may have a preventative effect in alleviating the negative effects of CIN. Similar to this, L-carnitine may play a major role in the stability of the antioxidant status in the kidney, liver, spleen and lung of the CIN rat model.

Renal tolerability of iopromide and iodixanol in 562 renally impaired patients undergoing cardiac catheterisation: the DIRECT study

AIMS

This multi-centre, randomised, double-blind study compared the nephrotoxicity of low-osmolar, low-viscous iopromide and iso-osmolar, high-viscous iodixanol in Chinese patients with moderate renal dysfunction, after coronary angiography or percutaneous coronary intervention (PCI).

METHODS AND RESULTS

The primary endpoint was contrast-induced nephropathy (CIN) on day 3, defined as a post-dose increase in serum creatinine (SCr) of ≥50% from baseline. All patients were rigorously hydrated from six hours before intervention. In 562 evaluable patients (of 592 recruited), the contrast volume, presence of diabetes mellitus, mean baseline SCr and estimated glomerular filtration rate (eGFR) were comparable between the iopromide- and iodixanol-treated groups. SCr increases of ≥50% occurred in 1/278 (0.4%) of patients after iopromide and 1/284 (0.3%) after iodixanol. Incidences in the secondary endpoints were the following: SCr increases of ≥0.5 mg/dL, 1.4% and 0.7%, respectively; SCr increases of ≥25%, 5.4% and 2.8%; eGFR decreases of ≥25%, 3.6% and 2.5%. Only one patient showed renal failure, one week after dosing with iodixanol. All differences were statistically insignificant, in the overall collective group and in the subgroup with diabetes (n=170).

CONCLUSIONS

With rigorous hydration, the CIN incidence was very low in patients with moderate renal dysfunction who underwent coronary angiography or PCI. No difference in nephrotoxicity was found between iopromide and iodixanol.

The neuro-critical care management of the endovascular stroke patient

OPINION STATEMENT

Acute ischemic stroke carries high morbidity and mortality. The advent of intravenous thrombolysis and endovascular reperfusion techniques have helped improve clinical outcomes for patients with large vessel acute ischemic stroke. The care of the post-endovascular stroke patient is complex and encompasses almost all aspects of medicine. Hemodynamics should be optimized post procedure to ensure adequate cerebral perfusion and strict hemodynamic parameters must be adhered to minimize reperfusion injury. Though no studies have specifically examined hemodynamic goals, our practice is to maintain a mean arterial pressure (MAP) > 70 and systolic blood pressure (SBP) < 140 for patients following successful recanalization. Early anti-thrombotic therapy is indicated in patients with stent placement. It remains less clear which patients may benefit from additional anticoagulation or therapy with IIb/IIIa inhibitors. Careful consideration must be paid to volume status to reduce risk of contrast nephropathy and maximize cerebral perfusion. Oral care and attention to dysphagia are key in preventing aspiration pneumonia. Glycemic control should be optimized to avoid excessive hyper and hypoglycemia. In the absence of data to guide treatment of anemia, our practice is to transfuse asymptomatic anemia when Hgb < 7 mg/dL, or if the patient is symptomatic or hemodynamically unstable. Neuro-protective strategies should be considered in the context of clinical trials until further studies are complete. At a minimum, fever should be treated aggressively. Young patients with good pre-morbid functional status who continue to have large volume infarcts may benefit from decompressive hemicraniectomy. When appropriate, aggressive and early mobilization is recommended to prepare patients for acute rehabilitation. Because randomized prospective data is lacking, patients should be encouraged to enroll in clinical trials to optimize care of this growing patient population.

Estimation of glomerular filtration rate in rabbits by a single-sample method using iodixanol

To estimate the glomerular filtration rate (GFR) in conscious rabbits, a single-sample method using the non-ionic contrast medium iodixanol was compared with a three-sample method using the standard agent inulin. Iodixanol and inulin were co-administered intravenously to male New Zealand White rabbits at 60 mg I/kg and 40 mg/kg, respectively, and blood was collected 30, 60, 90 and 120 min later. Serum iodixanol and inulin concentrations were separately determined by high performance liquid chromatography and colorimetry, respectively. Serum urea nitrogen (UN) and creatinine concentrations were also determined. Based on the data from healthy and cisplatin-treated rabbits, the GFR estimated by iodixanol was well consistent with that by inulin. Further, when the GFR decreased to more than 60% of the reference value, serum creatinine concentrations became elevated. However, serum UN concentrations exhibited wide fluctuations, presumably due to a difference in renal handlings. The single-sample method using iodixanol was considered to be an expedient tool in both clinical and research settings, because the stress due to a multi-sample method was reduced.

Dopamine-1 Receptor Agonist: Renal Effects and Its Potential Role in the Management of Radiocontrast-Induced Nephropathy

Radiocontrast-induced nephropathy remains the third leading cause of hospital-acquired acute renal failure. Once established, this syndrome is associated with increased morbidity and mortality as well as increased health care costs. Recently, studies have been initiated to evaluate the potential of a selective dopamine-1 receptor agonist (fenoldopam) in ameliorating radiocontrast-induced renal failure. Selective dopamine-1 receptor agonists exhibit many desirable renal effects that support their use for the prophylaxis of radiocontrast-induced nephropathy, including decreases in renal vascular resistance and increases in renal blood flow, glomerular filtration, and sodium and water excretion. Several reports have documented a beneficial effect of fenoldopam administration in attenuating radiocontrast-induced nephropathy. In contrast, a recent multicenter, randomized study did not demonstrate a renoprotective effect of fenoldopam against radiocontrast-induced nephropathy. The presence of multiple confounders, however, precludes a definitive conclusion regarding the ability of fenoldopam to protect against radiocontrast-induced nephropathy. Additional studies are needed to properly evaluate the role of fenoldopam in radiocontrast-induced nephropathy prophylaxis.

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.

Hepatocellular carcinoma in uremic patients: is there evidence for an increased risk of mortality?

BACKGROUND AND AIM

The clinical aspects of patients with hepatocellular carcinoma (HCC) undergoing maintenance dialysis are largely unknown. We aimed to investigate the long-term survival and prognostic determinants of dialysis patients with HCC.

METHODS

A total of 2502 HCC patients, including 30 dialysis patients and 90 age, sex, and treatment-matched controls were retrospectively analyzed.

RESULTS

Dialysis patients more often had dual viral hepatitis B and C, lower serum α-fetoprotein level, worse performance status, higher model for end-stage liver disease (MELD) score than non-dialysis patients and matched controls (P all < 0.05). There was no significant difference in long-term survival between dialysis and non-dialysis patients and matched controls (P = 0.684 and 0.373, respectively). In the Cox proportional hazards model, duration of dialysis < 40 months (hazard ratio [HR]: 6.67, P = 0.019) and ascites (HR: 5.275, P = 0.019) were independent predictors of poor prognosis for dialysis patients with HCC. Survival analysis disclosed that the Child-Turcotte-Pugh (CTP) provided a better prognostic ability than the MELD system. Among the four currently used staging systems, the Japan Integrated Scoring (JIS) system was a more accurate prognostic model for dialysis patients; a JIS score ≥ 2 significantly predicted a worse survival (P = 0.024).

CONCLUSIONS

Patients with HCC undergoing maintenance dialysis do not have a worse long-term survival. A longer duration of dialysis and absence of ascites formation are associated with a better outcome in dialysis patients. The CTP classification is a more feasible prognostic marker to indicate the severity of cirrhosis, and the JIS system may be a better staging model for outcome prediction.