RenalGuard System and Contrast Media (REMEDIALII)

Renal Insufficiency Following Contrast Media Administration Trial II (Remedial II): The RenalGuard System in High-Risk Patients for Contrast-Induced Acute Kidney Injury

The purpose of the present study is to assess the role of the RenalGuard System as compared to the optimal strategy (sodium bicarbonate infusion plus N-acetylcysteine (NAC)) in high and very-high risk patients to prevent contrast-induced acute kidney injury contrast induced acute kidney injury (CI-AKI). Consecutive patients with chronic kidney disease, referred to our institutions for coronary and/or peripheral procedures, will be randomly assigned to 1) prophylactic administration of sodium bicarbonate plus NAC (Systemic alone therapy group; n > 133) and 2) RenalGuard System treatment (RenalGuard group; n > 133). All enrolled patients must have an estimated glomerular filtration rate <30 ml/min/1.73 m2 and/or a contrast nephropathy risk score ≥11). In all cases iodixanol (an iso-osmolar, non ionic contrast agent) will be administered. The primary end point is an increase of >=0.3 mg/dL in the creatinine concentration 48 hours after the procedure. This study will give important answers on how to prevent CI-AKI in high and very-high risk patients undergoing contrast media exposure.

The strategy of volume supplementation by sodium bicarbonate plus N-acetylcysteine (NAC) seems to be the optimal pharmacological approach in preventing contrast induced acute kidney injury (CI-AKI) in patients at medium-to-high risk. Whether this prophylactic strategy is effective in high and very-high risk patients is unknown. In this subset of patients the potential protective effects and therapeutic advantage of a local delivery of protective compounds should be investigated. The RenalGuard™ System (PLC Medical Systes, Inc.) is a real-time measurement and real time matched fluid replacement device designed to accommodate the RenalGuard Therapy. The RenalGuard Therapy is based on the theory that creating and maintaining a high urine output is beneficial to patients undergoing imaging procedures where contrast agents are used. This should allow the body to rapidly eliminate contrast, reducing its toxic effects. The RenalGuard System seems to be ideal for the prevention of CI-AKI, by allowing an optimal urine flow rate >150 ml/h (ideally >300 ml/h). Preliminary data suggests that the RenalGuard System, by increasing the urine flow rate ≥ 300 ml/h, allows a quick renal first-pass elimination and therefore reduces the risk for contrast nephropathy. The potential benefits of RenalGuard Therapy are intended to reduce the incidence of CI-AKI via a combination of known physiological effects of high urine output including: a) lower concentration of contrast in the kidneys, b) more rapid transit of contrast through the kidneys, c) less overall exposure to toxic contrast, d) potential reduction of oxygen consumption in the medulla of the kidneys. No randomized study has been performed to assess the role of the RenalGuard System as compared to the optimal strategy (sodium bicarbonate infusion plus NAC) in high and very-high risk patients to prevent CI-AKI.

Systemic alone therapy group will be treated by intravenous sodium bicarbonate plus NAC administration. Patients allocated to the Systemic alone therapy group will receive 154 mEq/l of sodium bicarbonate in dextrose and H2O, according to the protocol reported by Merten et al. (9) The initial i.v. bolus was 3 ml/kg per hour for 1 hour immediately before contrast injection. Following this, patients will receive the same fluid at a rate of 1 ml/kg per hour during contrast exposure and for 6 hours after the procedure. All patients will receive NAC (Fluimucil, Zambon Group SpA, Milan, Italy) orally at a dose of 1200 mg twice daily on the day before and on the day of administration of the contrast agent (total of 2 days. Additional NAC dose (1.2 g) will be administered i.v. during the procedure.

Prophylactic controlled hydration with saline (0.9%) plus N-acetylcystein (NAC; 6 g in total). In the RenalGuard group, an initial bolus (priming) of 250 ml will be administered. In case of left ventricular dysfunction (ejection fraction ≤30%) and/or unstable hemodynamic conditions the bolus will be reduced to 150 ml. Following the initial bolus, furosemide (0.25 mg/kg) will be administered in order to achieve the optimal urine flow (≥300 ml/h). The hydration will be continued throughout the duration of the procedure and will last 4 hours following the procedure. Additional doses of furosemide are allowed in case of decrease of urine flow <300 ml/h.

The RenalGuard™ System (PLC Medical Systems, Inc.) is a real-time measurement and real time matched fluid replacement device designed to accommodate the RenalGuard Therapy. The RenalGuard Therapy is based on the concept demonstrated by clinical data that high urine output is beneficial to patients with impaired baseline renal function who receive intravascular iodinated contrast medio (CM). The RenalGuard System seems to be ideal for the prevention of CI-AKI, by allowing an optimal urine flow rate >300 ml/h. It is known that excessive diuresis can cause dehydration which increases the risk to the kidneys from CM. The RenalGuard System should allow the patient to achieve high urine output safely by maintaining the intravascular blood volume and avoiding the risk of over-or-under-hydration.

Patients allocated to the Systemic alone therapy group will receive 154 mEq/l of sodium bicarbonate in dextrose and H2O, according to the protocol reported by Merten et al. The initial intravenous bolus was 3 ml/kg per hour for 1 hour immediately before contrast injection. Following this, patients will receive the same fluid at a rate of 1 ml/kg per hour during contrast exposure and for 6 hours after the procedure. All patients will receive NAC (Fluimucil, Zambon Group SpA, Milan, Italy) orally at a dose of 1200 mg twice daily on the day before and on the day of administration of the contrast agent (total of 2 days)

The primary outcome measure will be the rate of development of CI-AKI in the 2 study arms (number of participants). CI-AKI is defined as an increase in the serum creatinine concentration >=0.3 mg/dL from the baseline value at 48 hours after administration of the contrast media or the need for dialysis.

an increase in the serum creatinine concentration >=0.25% and >=0.5 mg/dl at 48 hours after contrast exposure

Cystatin C is an alternative biomarker of kidney damage. Cystatin C seems to be superior to serum creatinine an identifying kidney function and damage.

NGAL is a new biomarker which seems to be very promising in detecting kidney injury. prelimiary data suggest that urine and serum NGAL increase very early (within few horurs) after the occurrence og acute kidney damage. Therefore, NGAL may be a real marker of acute kidney injury.

occurrence of renal failure requiring dialysis represents the haard endpoint of the study. Actually this represents the worst clinical consequence of CI-AKI.

The Rate of In-hospital Major Adverse Events (i.e. Acute Myocardial Infarction, c) Renal Failure Requiring Dialysis, and d) Acute Pulmonary Edema)

Assessment of the rate of in-hospital major adverse events (i.e. acute myocardial infarction, c) renal failure requiring dialysis, and d) acute pulmonary edema) will give important informantion on the clinical relevance of prophylactic strategies in preventing CI-AKI

Assessement of the cost-effectiveness ratio is important when testing a new strategy of both therapy and prophylaxis. The Renalguard system is more expensive than the conventional hydration regimen. The cost of RenalGuard system is approximately 800 $. This cost will be justified only if the system is more effective in preventing CI-AKI and improving the clinical outcome, expecially reducing the lenght of ospedalization and the rate of dialysis.

Inclusion Criteria: Age >=18 years Chronic kidney disease (estimated glomerular filtration rate <=30 ml/min/1.72 m2) and/or Risk score for contrast nephropathy ≥11 (according to the Mehran score; J Am Coll Cardiol 2004; 44: 1393-1399) Exclusion Criteria: Pregnancy Heart failure (NYHA functional class III-IV) Acute pulmonary edema Acute myocardial infarction Recent (<=2 days) contrast media exposure Patients enrolled in concomitant studies Administration of theophylline, dopamine, mannitol and fenoldopam. End-stage CKD (patients on chronic dialysis) Systemic hypotension (systolic blood pressure < 100 mg/dl). Multiple myeloma

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