Fluid administration strategies for the prevention of contrast-associated acute kidney injury.

PURPOSE OF REVIEW: The known timing of contrast media exposure in patients identified as high-risk for contrast-associated acute kidney injury (CA-AKI) enables the use of strategies to prevent this complication of intravascular contrast media exposure. Although multiple preventive strategies have been proposed, periprocedural fluid administration remains as the primary preventive strategy. This is a critical review of the current evidence evaluating a variety of fluid administration strategies in CA-AKI. RECENT FINDINGS: Fluid administration strategies to prevent CA-AKI include comparisons of intravenous (i.v.) to no fluid administration, different fluid solutions, duration of fluid administration, oral hydration, left ventricular end diastolic-pressure guided fluid administration and forced diuresis techniques. SUMMARY: Despite an abundance of fluid administration trials, it is difficult to make definitive recommendations about preventive fluid administration strategies due to low scientific quality of published studies. The literature supports use of i.v. compared with no fluid administration, especially in high-risk patients undergoing intra-arterial contrast media exposure. Use of isotonic saline is recommended over 0.45% saline or isotonic sodium bicarbonate. Logistical considerations support shortened over longer i.v. fluid administration strategies, despite an absence of evidence of equivalent efficacy. Current literature does not support oral hydration for high-risk patients. The use of tailored fluid administration in heart failure patients and forced diuresis with matching fluid administration are promising new fluid administration strategies.

Risks and Options With Gadolinium-Based Contrast Agents in Patients With CKD: A Review.

Gadolinium-based contrast agents (GBCAs) improve the diagnostic capabilities of magnetic resonance imaging. Although initially believed to be without major adverse effects, GBCA use in patients with severe chronic kidney disease (CKD) was demonstrated to cause nephrogenic systemic fibrosis (NSF). Restrictive policies of GBCA use in CKD and selective use of GBCAs that bind free gadolinium more strongly have resulted in the virtual elimination of NSF cases. Contemporary studies of the use of GBCAs with high binding affinity for free gadolinium in severe CKD demonstrate an absence of NSF. Despite these observations and the limitations of contemporary studies, physicians remain concerned about GBCA use in severe CKD. Concerns of GBCA use in severe CKD are magnified by recent observations demonstrating gadolinium deposition in brain and a possible systemic syndrome attributed to GBCAs. Radiologic advances have resulted in several new imaging modalities that can be used in the severe CKD population and that do not require GBCA administration. In this article, we critically review GBCA use in patients with severe CKD and provide recommendations regarding GBCA use in this population.

Contrast Media-Different Types of Contrast Media, Their History, Chemical Properties, and Relative Nephrotoxicity.

History of contrast dates back to the 1890s, with the invention of the radiograph. Nephrotoxicity has been a main limitation in ideal contrast media (CM). High-osmolar contrast media no longer are in clinical use due to overwhelming evidence supporting greater nephrotoxicity with these CM compared with current CM. Contrast-induced nephropathy (CIN) remains a common cause of in-hospital acute kidney injury. The choice contrast agent is determined mainly by cost and institution practice. This review focuses on the history, chemical properties, and experimental and clinical studies on the various groups of CM and their role in CIN.

The Controversy of Contrast-Induced Nephropathy With Intravenous Contrast: What Is the Risk?

Contrast-induced nephropathy (CIN) has long been observed in both experimental and clinical studies. However, recent observational studies have questioned the prevalence and severity of CIN following intravenous contrast exposure. Initial studies of acute kidney injury following intravenous contrast were limited by the absence of control groups or contained control groups that did not adjust for additional acute kidney injury risk factors, including prevalent chronic kidney disease, as well as accepted prophylactic strategies. More contemporary use of propensity score-adjusted models have attempted to minimize the risk for selection bias, although bias cannot be completely eliminated without a prospective randomized trial. Based on existing data, we recommend the following CIN risk classification: patients with estimated glomerular filtration rates (eGFRs) ≥ 45mL/min/1.73m2 are at negligible risk for CIN, while patients with eGFRs<30mL/min/1.73m2 are at high risk for CIN. Patients with eGFRs between 30 and 44mL/min/1.73m2 are at an intermediate risk for CIN unless diabetes mellitus is present, which would further increase the risk. In all patients at any increased risk for CIN, the risk for CIN needs to be balanced by the risk of not performing an intravenous contrast-enhanced study.

Use of Radiocontrast Agents in CKD and ESRD.

Contrast exposure in a population with chronic kidney disease (CKD) requires additional consideration given the risk of contrast-induced nephropathy (CIN) after exposure to iodinated contrast as well as systemic injury with exposure to gadolinium-based contrast agents (GBCA). Strategies to avoid CIN, and manage patients after exposure, including extracorporeal removal of contrast media, may differ among an advanced CKD population as compared to a general population. There is strong evidence to support the use of isotonic volume expansion and the lowest dose of low-osmolar or iso-osmolar contrast media possible to decrease CIN. The current literature on other newer prophylactic strategies such as statins, remote ischemic preconditioning, discontinuation of renin angiotensin aldosterone system (RAAS) blockade, and RenalGuard is limited thus these strategies cannot currently be recommended as routine prophylaxis for CIN. The use of extracorporeal removal of contrast agents as prophylaxis to reduce CIN has been the subject of multiple studies; however, data do not support a beneficial effect in reduction in CIN. Immediate removal of contrast by dialysis in a maintenance dialysis population is also not recommended, unless an individual's cardiopulmonary status is dependent on strict volume management. In patients with reduced renal function, GCBA exposure increases the risk of NSF. In patients with AKI, CKD stage 3 or greater (eGFR <30 ml/minute/1.73 m2 ), or patients on dialysis, we do not recommend the use of GBCA and alternative imaging modalities should be considered. If patients absolutely need magnetic resonance imaging with GBCA, we recommend the use of the lowest dose possible of the newer macrocylic, ionic agents (gadoterate meglumine) as well as immediate postprocedural HD in patients already on HD or peritoneal dialysis or with stage 5 CKD and with a functioning dialysis access already in place.

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.

Renal failure in patients with left ventricular assist devices.

Implantable left ventricular assist devices (LVADs) are increasingly being used as a bridge to transplantation or as destination therapy in patients with end stage heart failure refractory to conventional medical therapy. A significant number of these patients have associated renal dysfunction before LVAD implantation, which may improve after LVAD placement due to enhanced perfusion. Other patients develop AKI after implantation. LVAD recipients who develop AKI requiring renal replacement therapy in the hospital or who ultimately require long-term outpatient hemodialysis therapy present management challenges with respect to hemodynamics, volume, and dialysis access. This review discusses the mechanics of a continuous-flow LVAD (the HeartMate II), the effects of continuous blood flow on the kidney, renal outcomes of patients after LVAD implantation, dialysis modality selection, vascular access, hemodynamic monitoring during the dialytic procedure, and other issues relevant to caring for these patients.

Nephrotoxicity of iodixanol versus ioversol in patients with chronic kidney disease: the Visipaque Angiography/Interventions with Laboratory Outcomes in Renal Insufficiency (VALOR) Trial.

BACKGROUND: Iso-osmolar contrast medium iodixanol has been reported to be less nephrotoxic than selected low-osmolar contrast media (LOCM) in chronic kidney disease (CKD) patients with diabetes mellitus. This study compared the nephrotoxicity of iodixanol and the LOCM ioversol in CKD patients undergoing coronary angiography. METHODS: This is a prospective double-blind trial in 337 patients with stable CKD who were randomly assigned to receive the iso-osmolar contrast medium iodixanol or the LOCM ioversol. The co-primary end points were the mean peak percentage change (MPPC) in baseline serum creatinine and the incidence of contrast-induced nephropathy (rise of > 0.5 mg/dL in baseline serum creatinine within 72 hours postcontrast) for the 2 contrast media in the 72-hour period after contrast administration. Prespecified analyses included stratification on diabetic state and the use of N-acetylcysteine. RESULTS: In the 299 patients with complete post-contrast media creatinine data, the incidence of contrast-induced nephropathy was 21.8% in the iodixanol subjects and 23.8% in the ioversol subjects (P = .78). For all patients, the MPPC was 14.7% with iodixanol and 20.0% with ioversol (P = .06), whereas in the subset of diabetic patients, this value was significantly lower in the iodixanol (12.9%) compared with the ioversol subjects (22.4%, P = .01). CONCLUSIONS: Overall, the nephrotoxicity associated with iodixanol was not significantly different from that observed with ioversol in CKD patients undergoing coronary angiography, although in diabetic patients, MPPC was significantly lower in the iodixanol group.

Clinical significance and preventive strategies for contrast-induced nephropathy.

PURPOSE OF REVIEW: Contrast-induced nephropathy continues to be a common cause of in-hospital acute kidney injury. Published studies on pathogenesis, clinical significance, diagnosis, and preventive measures have dramatically increased significantly in the past several years. This review will focus on new developments in contrast-induced nephropathy. RECENT FINDINGS: Studies on the clinical significance of contrast-induced nephropathy are reviewed along with initial reports of biomarkers in diagnosing this complication of iodinated contrast administration. Emerging literature on the relative nephrotoxicity of iso-osmolar versus low-osmolar contrast media and the value of bicarbonate hydration are discussed. More recent preventive measures using prostacyclin, 'statins', and erythropoietin are also reviewed. SUMMARY: Contrast-induced nephropathy is an increasing cause of acute kidney injury and is associated with significant mortality and morbidity. Future developments in this field will focus on refining the clinical significance of this complication, earlier diagnosis with biomarkers, clarifying the role for bicarbonate and iso-osmolar contrast agents as preventive strategies, and the introduction of new prophylactic techniques on the basis of an improved understanding of pathogenesis at the cellular level.

Contrast-induced nephropathy: how it develops, how to prevent it.

No current treatment can reverse or ameliorate contrast-induced nephropathy once it occurs, but prophylaxis is possible. Many preventive measures have failed to show benefits in well-designed, prospective, randomized, double-blinded trials. This review will focus only on the prophylactic strategies that have possible or proven value.

Hemodialysis-related venous stenosis: treatment with ultrahigh-pressure angioplasty balloons.

The authors retrospectively reviewed the use of ultrahigh-pressure angioplasty balloons at atmospheric pressures at or above the manufacturer recommended burst pressure (30 atm) for the treatment of resistant hemodialysis-related venous stenosis at their institution. In seven of 87 procedures, high-pressure angioplasty (up to 27 atm) was unsuccessful. By coupling new balloon technology with aggressive inflation pressures, 100% technical success was achieved in the treatment of stenoses that were resistant to high-pressure angioplasty in these seven procedures. This approach could potentially offer cost savings compared with the costs of other previously described treatment methods for resistant lesions, such as atherectomy devices and cutting balloons.