Festschrift for Professor Claude Jacobs. Nephrotoxicity of contrast media

Contribution of platelets indices in the development of contrast-induced nephropathy

Contrast-induced nephropathy (CIN) accounts for 10% of hospital-acquired renal failure, causes a prolonged in-hospital stay and represents a powerful predictor of poor clinical outcome. The underlying mechanism of the CIN development remains unclear and seems to be multifactorial. The potential link between platelet indices such as mean platelet volume (MPV) and platelet distribution width (PDW) with CIN is unknown. Herein, we aimed to investigate the correlation between MPV and PDW levels with the development of CIN. The incidence of CIN (20.5%) was prospectively evaluated in 430 patients with diagnosis of acute coronary syndrome. Initial creatinine (1.13 ± 0.25 vs. 1.05 ± 0.27 mg/dl, P = 0.01) and PDW (40.1 ± 20.2 vs. 34.5 ± 19.9%, P = 0.02) levels and the total volume of contrast media used (121 ± 61 vs. 94 ± 42 ml, P = 0.01) were higher in patients who developed CIN. MPV was similar between the two groups (P = 0.80). In a univariate regression analysis, age, increased creatinine, uric acid, phosphate, PDW levels and higher total volume of contrast media used were significantly correlated with CIN incidence. However, in a multivariate analysis, only total volume of CM used [odds ratio (OR) 1.011, 95% confidence interval (CI) 1.006-1.016; P = 0.01], increased age (OR 1.026, 95% CI 1.00-1.052; P = 0.05) and increased PDW levels (OR 1.009, 95% CI 1.00-1.022; P = 0.04) remained as the independent predictors of CIN. Among platelet indices, PDW, but not MPV, was associated with CIN development. The clinical significance of such link remains unclear, but may indicate involvement of platelet activation in CIN pathogenesis.

Direct coronary stenting in reducing radiation and radiocontrast consumption

Introduction

Coronary stenting is the primary means of coronary revascularization. There are two basic techniques of stent implantation: stenting with balloon predilatation of stenosis and stenting without predilatation (direct stenting). Limiting the time that a fluoroscope is activated and by appropriately managing the intensity of the applied radiation, the operator limits radiation in the environment, and this saves the exposure to the patient and all personnel in the room. Nephrotoxicity is one of the most important properties of radiocontrast. The smaller amount of radiocontrast used also provides multiple positive effects, primarily regarding the periprocedural risk for the patients with the reduced renal function. The goal of the study was to compare fluoroscopy time, the amount of radiocontrast, and expenses of material used in direct stenting and in stenting with predilatation.

Patients and methods

In a prospective study, 70 patients with coronary disease were randomized to direct stenting, or stenting with predilatation.

Results

Fluoroscopy time and radiocontrast use were significantly reduced in the directly stented patients in comparison to the patients stented with balloon-predilatation. The study showed a significant reduction of expenses when using a direct stenting method in comparison to stenting with predilatation.

Conslusions

If the operator predicts that the procedure can be performed using direct stenting, he is encouraged to do so. Direct stenting is recommended for all percutaneous coronary interventions when appropriate conditions have been met. If direct stenting has been unsuccessful, the procedure can be converted to predilatation.

The role of dialysis in contrast-induced nephropathy: doubts and certainties

Over past years, there has been a progressive increase in percutaneous endovascular procedures in patients with chronic renal disease, owing to the high incidence of vascular disease, particularly coronary artery disease, in this population. The use of contrast media may further worsen renal function in such patients, in some cases even accelerating the progression towards end-stage renal failure, and may increase patient morbidity and mortality. In this review, we discuss the role of dialysis in preventing contrast-induced nephropathy as well as present indications to its use in patients already on dialysis treatment undergoing diagnostic or therapeutic procedures with contrast medium injection.

Contrast-Induced Nephropathy

Contrast-induced nephropathy (CIN) is a well-recognized complication of radiographic contrast administration and is the third leading cause of hospital-acquired renal insufficiency. The use of contrast media is increasing, particularly in the area of endovascular therapy. Vascular interventionists need to be aware of strategies to reduce the risk of CIN. Numerous trials, meta-analyses, and expert guidelines for the prevention of CIN have been published between 1966 and 2006, but the majority of studies have been conducted on patients undergoing coronary interventions; few have involved vascular surgical population. The literature suggests that adequate hydration is essential in all patients due to receive contrast. No pharmacological agents have been shown to conclusively reduce the risk. Forced diuresis is harmful, and there is insufficient evidence to support routine use of hemodialysis or hemofiltration. Well conducted studies of other potential prophylactic techniques are needed in vascular populations.

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.

Effect of radiocontrasts on selected membrane transport systems

BACKGROUND

This study was aimed at examining the effects of radiocontrast agents on selected membrane transport functions.

METHODS

The effect of diatrizoate sodium (DS), diatrizoate meglumine (DM), and diatrizoate compound (DC) on Na+/K+ pump activity and number, L-arginine, and choline transports were evaluated in erythrocytes of normal individuals and patients undergoing cardiac catheterization.

RESULTS

Norrmal individuals' erythrocytes potassium influxes were 1.50+/-0.35, 1.32+/-0.37, 1.28+/-0.30, and 1.01+/-0.25 mmol/L cell/h in control, DS, DM, and DC groups, respectively (P=0.004; DC vs. control). Patients exposure to Hypaque M-76 significantly diminished Na+/K+ pump activity (1.40+/-0.36 before, vs. 1.27+/-0.40 mmol/L cell/h after; P=0.039). The number of Na+/K+ pumps was reduced (156+/-36 vs. 143+/-34 pumps/erythrocyte; P=0.015) in presence of DS. L-arginine and choline transports changed only at high radiocontrast concentrations.

CONCLUSION

Selective changes in erythrocytes membrane transport function take place on exposure to radiocontrasts.

Néphropathie induite par les produits de contraste iodés, l’épuration extrarénale est-elle efficace en prevention ?

A FREQUENT AND EXPENSIVE PROBLEM: Ninety percent of contrast media nephrotoxicity (CMN) occur in patients with pre-existing kidney failure. Its aggravation may require early chronic dialysis.

PREVENTIVE MEASURES

CMN prophylaxis is important in these patients. Pre- and post-hydration, with infusion of isotonic saline solution or sodium bicarbonate, and reduction of contrast medium (CM) volume to the strict minimum are essential for preventing CM-induced kidney failure. THE INTEREST OF PROPHYLACTIC HEMODIALYSIS AND HEMOFILTRATION: An interesting approach in preventing CMN is the early elimination of the CM with dialysis techniques. Preventive hemodialysis does not reduce the risk of CMN, but hemofiltration has shown significant efficacy in a population of patients with kidney failure. THE INTEREST OF IMMEDIATE HEMODIALYSIS IN CHRONIC HEMODIALYSIS PATIENTS: Although nephrotoxicity is no longer a problem in patients undergoing chronic hemodialysis, CM, especially in high-dose injections, may be responsible for fluid and electrolyte abnormalities and/or volemic expansion. No data yet justify a conclusion that a hemodialysis session immediately after injection of a CM in chronic dialysis patients might be helpful.

Causes of acute renal dysfunction after percutaneous coronary intervention and comparison of late mortality rates with postprocedure rise of creatine kinase-MB versus rise of serum creatinine

Increases in both serum creatinine and creatine kinase-MB (CK-MB) after percutaneous coronary intervention are associated with increased risk for late adverse cardiovascular events. In 5,397 patients, the strength of the association of each with late events and the risk factors for each of these markers were compared. A postprocedural increase in creatinine was a more powerful predictor of late mortality than an increase in CK-MB. Risk factors for an increase in creatinine are similar to those for contrast-induced nephropathy, suggesting that vulnerability to such injury may identify patients with increased risk for late mortality.

Understanding Contrast Media

More than 10 million radiologic examinations requiring intravascular injection of iodinated contrast media are performed in the United States each year. Iodinated contrast media are considered to be safe diagnostic drugs, and the incidence of adverse reaction is low. However, as with any drug, the administration of contrast media is not without risk. Nurses involved in patient care should have some understanding of the properties and potential effects of iodinated contrast media.

Contrast nephropathy : an evidence-based approach to prevention

Contrast-induced nephropathy occurs in 2-10% of patients exposed to intravascular radiographic contrast agents and results in significant morbidity and mortality. Although the exact mechanism of this disorder has not been fully elucidated, contrast nephropathy is probably due to a combination of decreased renal medullary blood flow, resulting in medullary ischemia, and direct toxicity to renal tubules. Contrast nephropathy is most commonly defined as either a >25% increase or a >0.5 mg/dL rise in serum creatinine level within 48 hours of contrast medium exposure. Baseline characteristics associated with an increased risk for development of contrast nephropathy include the presence of baseline renal dysfunction, diabetes mellitus, congestive heart failure, volume depletion, and concomitant administration of nephrotoxic drugs. Many strategies have been investigated in an effort to prevent the occurrence of renal dysfunction following contrast media exposure. Intravenous hydration has been shown to significantly decrease the incidence of nephropathy in high-risk patients. However, trials of several prophylactic pharmacologic interventions have been mostly disappointing, including the administration of calcium channel antagonists, diuretics, dopamine, endothelin receptor antagonists and fenoldopam. The use of N-acetylcysteine has been shown in some trials to decrease the incidence of contrast nephropathy in patients with a baseline renal dysfunction, and should currently be strongly considered in this high-risk patient subgroup in addition to hydration. Our purpose is to review the contemporary literature regarding contrast-induced renal dysfunction and present an evidence-based approach for prevention of this complication.

Effects of two dimeric iodinated contrast media on renal medullary blood perfusion and oxygenation in dogs

RATIONALE AND OBJECTIVES

To compare the effects of two iodinated contrast media, iodixanol and ioxaglate, on outer medullary blood flow (MBF) and oxygen tension (MPO(2)) in the dog kidney.

METHODS

Iodixanol and ioxaglate were injected selectively into the renal artery (320 mgI/kg) of anesthetized Beagle dogs. MBF and MPO(2) were measured with a laser-Doppler probe and an oxygen-sensing microelectrode implanted in the outer medulla. Urine samples were collected for viscosity and osmolality measurements.

RESULTS

Both contrast media produced a moderate decrease in MBF and MPO(2). The hypoperfusion and hypoxia lasted significantly longer with iodixanol than with ioxaglate. Theophylline, an adenosine receptor antagonist, partially prevented iodixanol-induced hypoxia. Urine viscosity was dramatically increased by iodixanol but not by ioxaglate. Urine osmolality did not differ significantly between groups.

CONCLUSION

Iodixanol produced a more sustained medullary hypoxia than ioxaglate when injected selectively into the dog renal artery. This may lead to hypoxic cellular damage and subsequent impairment of kidney functions.

Prevention of contrast media-induced renal dysfunction with prostaglandin E1: a randomized, double-blind, placebo-controlled study

Preexisting renal impairment is an all-encompassing risk factor for radiocontrast-associated nephrotoxicity. Renal impairment appears to be associated with the inadequate production of renal prostaglandins at the critical time of radiocontrast administration and for a variable time period afterward. We prospectively studied 130 patients with chronic renal insufficiency (serum creatinine > or =1.5 mg/dL) who were undergoing radiocontrast administration. Using a double-blind, randomized, prospective technique, patients were assigned to either placebo or one of three prostaglandin E1 (PGE1) treatment groups (10, 20, or 40 ng/kg/min). Infusion was started 60 +/- 30 minutes before the administration of radiocontrast and was continued for a total of 6 hours. In the placebo group, radiocontrast administration resulted in a mean increase (+/- SD) in serum creatinine of 0.72 +/- 1.15 mg/dL at 48 hours. This increase was less in each of the PGE1 treatment groups after 48 hours, with a significant difference between placebo and the 20 ng/kg/min PGE1 group (P = 0.01). Using baseline adjusted means, analysis of covariance with baseline serum creatinine as the covariable demonstrated significant differences between the placebo and 20 ng/kg/min PGE1 group (P = 0.03) and between the placebo and 10 ng/kg/min PGE1 group P = 0.047). In a subgroup analysis of the diabetic patients, the increase in serum creatinine was less pronounced in the three PGE1 groups versus the placebo group, and the 20 ng/kg/min PGE1 group had the most favorable outcome. The parenteral administration of PGE1 immediately before radiocontrast exposure and continued for a period of 5 to 5.5 hours significantly reduced the elevation of serum creatinine poststudy. The most effective of the three PGE1 dosing regimens was 20 ng/kg/min.