Preventing complications of radiographic contrast media: is there a role for dialysis?

Clinical pearls in hospital nephrology

Hospitalized patients who have established kidney disease and those who have acute kidney injury in the hospital, along with patients with electrolyte disturbances tend to be some of the most complex to care for. Through working closely in nephrology consultation in the hospital with patients and providers, in both private and academic settings, we have come to encounter certain common presentations and recurrent themes that are worthy of emphasis, and of which a good understanding can translate into improved patient care. For the provider who works closely with such patients, many of these aspects are important to recognize and understand. In this review, we present 10 questions that address some of the highly relevant aspects of nephrology for the provider in the hospital. Through a MEDLINE database search, we reviewed the most pertinent studies as we then go through the explanation of management decisions in an evidence-based methodology with an up-to-date approach based on the current literature on the subject.

Coronary Artery Disease in patients with End-Stage Kidney Disease; Current perspective and gaps of knowledge

Coronary artery disease (CAD) is very common in dialysis patients. One third have preexisting CAD and another one third have significant occult disease at the time of starting dialysis. Symptoms are often absent or are atypical, emphasizing the need for vigorous screening, specifically in patients awaiting transplant. The lesions tend to be heavily calcified, diffuse, and involve multiple vessels, consequently, percutaneous coronary interventions are more complicated to perform, and are less successful in achieving and maintaining short- and long-term patency. Dialysis patients have been excluded from the randomized controlled trials on which the current standards for managing CAD have been established. Due to differences in pathobiology and risks and benefits, it is uncertain that the results of these clinical trials extrapolate to patients with advanced chronic kidney disease (CKD). Here we review the data from observational studies and identify special considerations concerning the diagnosis and management of CAD in dialysis patients, including the use of noninvasive functional testing vs anatomical testing, the management of acute coronary syndromes and of stable coronary artery disease, the role for percutaneous revascularization vs coronary artery bypass grafting, and of platelet inhibitor therapy after coronary stenting. We review the preliminary results of the recently published ISCHEMIA-CKD trial, the only trial to date to involve large numbers of dialysis patients. This is the first of, hopefully, many trials in the pipeline that will examine therapies for CAD specifically in patients with advanced CKD, a growing population that is at particularly high risk for poor outcomes.

Predictive factors for contrast-induced acute kidney injury in high-risk patients given N-acetylcysteine prophylaxis

BACKGROUND

Contrast-induced acute kidney injury (CI-AKI) is rec.ognized as a common complication of radiographic contrast-enhanced procedures. N-acetylcysteine (NAC) is commonly prescribed, but CI-AKI can still develop despite NAC administration as prophylaxis.

OBJECTIVE

Identify the predictive factors for development of CI-AKI in patients prescribed NAC.

DESIGN

Prospective, cross-sectional.

SETTING

A tertiary hospital in Malaysia.

PATIENTS AND METHODS

All adult patients who were prescribed NAC for prevention of CI-AKI were identified through an NAC drug us.age monitoring card maintained by the inpatient pharmacy. The study was conducted from March to July 2017.

MAIN OUTCOME MEASURES

Statistically significant predictive fac.tors for development of CI-AKI despite NAC administration.

SAMPLE SIZE

152 RESULTS: The most commonly recognized risk factors for CI-AKI present in the study population were renal impairment (n=131, 86.2%), anemia (n=107, 70.4%), and diabetes mellitus (n=90, 59.2%). Hydration therapy was initiated in 128 patients (84.2%) prior to the contrast-enhanced procedure. Sixty-one (40.1%) were treated with nephrotoxic medications concomitantly with NAC. Fifteen (9.9%) patients developed AKI. Hypotension (OR: 6.02; 95% CI 1.25-28.97) and use of high contrast volume (OR: 6.56; 95% CI: 1.41-30.64) significantly increased the odds for AKI. Prior hydration therapy (OR: 0.13; 95% CI 0.03-0.59) showed protective effects.

CONCLUSION

The risk predictors identified for CI-AKI were hypotension, high contrast volume and prior hydration therapy.

LIMITATION

May not have identified other confounding factors for development of CI-AKI.

CONFLICT OF INTEREST

None.

Radiographic and magnetic resonances contrast agents: Essentials and tips for safe practices

With extended and continued expansion of medical imaging utilization in modern medical practice over last decade, radiologists as well as other faculty staff dealing with radiographic and magnetic resonances contrast media (CM) have to be well oriented with their potential hypersensitivity reactions and recognize high-risk groups liable to develop it and enable early recognition. Radiologists and other medical staff involved in administration and dealing with CM have to be ready to implement prompt, practical and effective management plan to deal with these scenarios should they emerge. Strategies to prevent potential contrast-induced acute and delayed renal injuries have to be routinely exercised. Paying attention to the pregnant and nursing women, pediatrics, diabetics, as well as other fragile populations is of utmost importance for patient safety during contrast administrations. Radiologists should play a pivotal role in orienting patients about necessity to use CM for their imaging studies, in case it is needed, and assure them about its safety. Moreover, they have to be oriented with the medico-legal issues related to use of CM. These will pay as improved patient safety as well as safe daily working environmentat different levels of radiology practices.

Imaging in Vascular Access

This review examines four imaging modalities; ultrasound (US), digital subtraction angiography (DSA), magnetic resonance imaging (MRI) and computed tomography (CT), that have common or potential applications in vascular access (VA). The four modalities are reviewed under their primary uses, techniques, advantages and disadvantages, and future directions that are specific to VA. Currently, US is the most commonly used modality in VA because it is cheaper (relative to other modalities), accessible, non-ionising, and does not require the use of contrast agents. DSA is predominantly only performed when an intervention is indicated. MRI is limited by its cost and the time required for image acquisition that mainly confines it to the realm of research where high resolution is required. CT’s short acquisition times and high resolution make it useful as a problem-solving tool in complex cases, although accessibility can be an issue. All four imaging modalities have advantages and disadvantages that limit their use in this particular patient cohort. Current imaging in VA comprises an integrated approach with each modality providing particular uses dependent on their capabilities. MRI and CT, which currently have limited use, may have increasingly important future roles in complex cases where detailed analysis is required.

Contrast-induced acute kidney injury: A review of practical points

Contrast-induced acute kidney injury (CI-AKI) is one of the most common causes of AKI in clinical practice. CI-AKI has been found to be strongly associated with morbidity and mortality of the patients. Furthermore, CI-AKI may not be always reversible and it may be associated with the development of chronic kidney disease. Pathophysiology of CI-AKI is not exactly understood and there is no consensus on the preventive strategies. CI-AKI is an active research area thus clinicians should be updated periodically about this topic. In this review, we aimed to discuss the indications of contrast-enhanced imaging, types of contrast media and their impact on nephrotoxicity, major pathophysiological mechanisms, risk factors and preventive strategies of CI-AKI and alternative non-contrast-enhanced imaging methods.

[Renal toxicity of contrast agents in oncologic patients]

Cancer patients frequently undergo imaging examinations to diagnosis but also to evaluate their responses to treatment. These patients are also at high risk of kidney impairment before considering the possible nephrotoxicity of their chemotherapy. In this context, it is overriding to know contrast agents induced risks and what are the good practices to avoid them. Renal function evaluation takes a major part in there. The X-ray radiology using iodinated contrast agent (ICA) exposes patients to acute renal failure. This induced nephropathy is prevented by adequate hydration prior to injection when the glomerular filtration rate (GFR) of the patient is less than 60 ml/min/1.73 m(2). For hardly nephrotoxic, gadolinium-based contrast agents (GBCA) injected in magnetic resonance imaging, were considered for a long as a safe alternative to ICA. Yet they may induce nephrogenic systemic fibrosis (NSF). The recommendations of European and U.S. drugs safety agencies have recently converged defining groups at risk of NSF based on the level of patients GFR and the type of GBCA used. How to assess the risk-benefit balance of the cancer patient for whom you should choose an informative, effective and safe imaging examination?

Iodinated contrast media and the role of renal replacement therapy

Iodinated contrast media are among the most commonly used pharmacologic agents in medicine. Although generally highly safe, iodinated contrast media are associated with several adverse effects, most significantly the risk of acute kidney injury, particularly in patients with underlying renal dysfunction. By virtue of their pharmacokinetic characteristics, these contrast agents are efficiently cleared by hemodialysis and to a lesser extent, hemofiltration. This has led to research into the capacity for renal replacement therapies to prevent certain adverse effects of iodinated contrast. This review examines the molecular and pharmacokinetic characteristics of iodinated contrast media and critically analyzes data from past studies on the role of renal replacement therapy to prevent adverse effects of these diagnostic agents.

Dialytic therapies to prevent NSF following gadolinium exposure in high-risk patients

Prolonged exposure to gadolinium-based contrast (GBC) appears to be the core pathophysiologic factor in the development of nephrogenic systemic fibrosis (NSF). As the GBC is renally excreted, this condition is predominantly seen only following exposure in patients with severe reductions in renal function. Fortunately, GBC is easily hemodialyzed with 95% of an administered dose removed after two hemodialysis sessions. Peritoneal dialysis, on the other hand, is not an efficient means of GBC removal. This has led to recommendations to hemodialyze a high-risk patient immediately following GBC administration and to repeat the treatment the following day. Although this approach seems logical and is more aggressive than the usual thrice-weekly hemodialysis schedule that most patients were receiving when they developed this devastating condition, there are no data to support the supposition that this approach will reduce the risk of NSF. Therefore, although an aggressive hemodialysis strategy postexposure is not unreasonable, it is probably best at this point to try to avoid GBC administration altogether in these high-risk patients.

Editorial: Gadolinium Use in Patients with Kidney Disease: A Cause for Concern

Gadolinium is widely used as a magnetic resonance imaging contrast agent and is considered to have a good overall safety profile. Recently, both renal and extra-renal toxicities have been reported following exposure to gadolinium in patients with underlying kidney disease. Gadolinium-related contrast-induced nephropathy appears to be a risk in patients with advanced kidney disease and especially those with diabetic nephropathy. Even more concerning is the strong association of gadolinium with nephrogenic systemic fibrosis (NSF), a devastating fibrosing disorder of the skin and other systemic organs. Although cause and effect have not been proven for the NSF-gadolinium link, the impaired renal elimination of gadolinium in patients with kidney disease and the instability of gadolinium-chelate binding may expose tissues to toxic free Gd(3+) and promote this fibrosing disorder. Caution should be exercised when utilizing gadolinium as a contrast agent in patients with advanced CKD or ESRD.