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

Acute Kidney Injury after Cardiac Surgery: Risk Factors and Novel Biomarkers

Acute kidney injury (AKI) is a common and severe complication after cardiac surgery. Currently, a series of novel biomarkers have favored the assessment of AKI after cardiac surgery in addition to the conventional indicators. The biomartkers, such as urinary liver fatty acid binding protein (L-FABP), urinary neutrophil gelatinase-associated lipocalin (NGAL), serum L-FABP, heart-type FABP, kidney injury molecule 1 (KIM-1), and interleukin-18 were found to be significantly higher in patients who developed AKI after cardiac surgery than those who did not. Apart from urinary interleukin-18, the novel biomarkers have been recognized as reliable indicators for predicting the diagnosis, adverse outcome, and even mortality of AKI after cardiac surgery. The timing of the renal replacement therapy is a significant predictor relating to patients’ prognoses. In patients with AKI after cardiac surgery, renal replacement therapy should be performed as early as possible in order to achieve promising outcomes. In children, AKI after cardiac surgery can be managed with peritoneal dialysis. AKI after cardiac surgery has received extensive attention as it may increase early mortality and impact long-term survival of patients as well. The purpose of this article was to analyze the changes of the pertinent biomarkers, to explore the related risk factors leading to the occurrence of AKI after cardiac surgery, and to provide a basis for the clinical prevention and reduction of AKI.

Fenoldopam for the prevention of contrast-induced nephropathy (CIN)-do we need more trials? A meta-analysis

We conducted a pooled analysis of clinical trials comparing intravenous Fenoldopam (FP) with Saline/Placebo/N-acetyl cysteine (NAC) for the prevention of contrast-induced nephropathy (CIN). Five studies were eligible. Quantitative analyses were done with Review Manager (RevMan version 5.2.). A total of 85 out of 353 patients in Fenoldopam group while 73 among 366 in the control group were affected due to CIN. The risk ratio for the development of CIN in the Fenoldopam group was 1.19 compared to the control group. This was not statistically significant. Fenoldopam is no better than Placebo/Saline or NAC in preventing CIN, but more studies are required.

Facts and fallacies concerning the prevention of contrast medium-induced nephropathy

OBJECTIVE

The aim of this article is to extract from recent medical literature and nephrologic practice the facts and fallacies concerning the possible prophylaxis of contrast medium-induced nephropathy.

DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION

A MEDLINE/PubMed search (1985 to January 2006) was conducted, including all relevant articles investigating the pathogenesis and prevention of contrast medium-induced nephropathy from a nephrologic critical point of view.

DATA SYNTHESIS

Considerable efforts have been made to develop pharmacologic therapy for the prevention of contrast medium-induced nephropathy, especially in patients at risk, such as elderly subjects and those with preexisting renal impairment, hypovolemia, or dehydration. There is general consensus that hydration protocols implemented before and after imaging with contrast medium may be effective in preventing contrast medium-induced nephropathy. However, definitive and convincing data related to amounts to be infused, infusion timing, and type of solutions (half-isotonic, isotonic saline solution, or bicarbonate) are lacking. Forced diuresis with furosemide or mannitol and use of dopamine, together with concomitant hydration, have been proved to be ineffective or even more risky in the event of inadequate maintenance of euvolemia. Various direct or indirect vasodilators have been investigated (atrial natriuretic peptide, calcium channel blockers, angiotensin-converting enzyme inhibitors, and endothelin receptor antagonists), yet results have been inconsistent and inconclusive. Recent large meta-analyses concerning the protective role of antioxidant action of N-acetylcysteine have led to the conclusion that the statistical significance of the results is borderline. Preventive hemodialysis has not proved to be useful; on the contrary, it might worsen the clinical conditions by inducing hypotension. Hemofiltration, despite some positive studies, is too complex and cannot be used extensively.

CONCLUSIONS

: It is believed that prevention is actually achieved by correcting hypovolemia, dehydration, or both. Normalization of body fluids is probably the true objective to be achieved by preventive measures in all patients, not only in those at risk. Because limited data have been collected in intensive care units, at present, no firm or specific recommendations can yet be provided for the critically ill.

Strategies to reduce the risk of contrast nephropathy: an evidence-based approach

PURPOSE OF REVIEW

Contrast nephropathy is a common complication associated with angiographic procedures that carries significant morbidity and mortality. Recent clinical trials of prophylactic strategies have reported contradictory results. This review presents recent insights into the pathophysiology of contrast nephropathy and reviews trial results in this context.

RECENT FINDINGS

A prediction rule has been developed to better identify patients at risk of developing contrast nephropathy. Factors other than osmolality play a significant role in the pathogenesis of contrast nephropathy, at least for agents with osmolalities of 800 mOsm/kg or less. New randomized trial data do not support a role for N-acetylcysteine in contrast nephropathy prophylaxis and there is additional evidence that fenoldopam is ineffective. Pooled analyses of theophylline prophylaxis trials are inconclusive. Theoretical and clinical data suggest that ascorbic acid may be renoprotective, but this requires further study.

SUMMARY

The overall incidence of contrast nephropathy remains low. Available evidence supports the use of hydration and low volumes of iso-osmolar or low-osmolar contrast in patients at risk of developing contrast nephropathy. Heterogeneity has affected interpretability of interventional trials of N-acetylcysteine or theophylline prophylaxis strategies. Future clinical trials must identify and target moderate-risk to high-risk patients and ensure that proven therapies are included in trial protocols.

ASDIN Original Investigations: Venous Mapping Using Venography and the Risk of Radiocontrast-Induced Nephropathy

Venous mapping using venography has been considered to be the gold standard for identifying veins suitable for arteriovenous fistula (AVF) creation. By utilizing a radiocontrast medium, however, venography introduces the risk of radiocontrast-induced nephropathy. The risk of this complication in the chronic kidney disease (CKD) population has not been previously studied. Twenty-five consecutive patients (CKD stage 4 and 5) undergoing venography were enrolled in this study. Patients were advised not to fast for the procedure and were encouraged to take oral fluids. Radiocontrast-induced nephropathy was defined as a 20% decrease in the estimated glomerular filtration rate (GFR) from the baseline value at 48 hours after contrast administration. Weekly telephone calls were made for a total of 4 weeks to assess the need for dialysis. Venography was performed by interventional nephrology using 10-20 cc of low osmolarity contrast medium. Data were collected prospectively. Median age was 48.9 +/- 7.8 years and 52% of the patients had diabetes. Complete sets of pre- and postprocedure GFRs were available in 21 patients. At 48 hours, there were no differences between the pre- and postprocedure GFRs. At the third week, one patient developed flu-like symptoms with severe gastroenteritis and was hospitalized for volume depletion. This patient initiated dialysis during the hospital stay. We conclude that at 48 hours, our cohort did not develop radiocontrast-induced nephropathy. During the 4-week phone call follow-up, only one patient needed dialysis. Large-scale studies with a longer follow-up using GFR estimation are needed to confirm these preliminary findings.