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Hydration before contrast cuts CIN in high-risk patients.

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Even patients with advanced kidney disease can steer clear of contrast-induced nephropathy (CIN) if given plenty of hydration, say researchers from the Netherlands. Results from the study of nearly 1,000 patients with stage 3 or 4 kidney disease were published in the June issue of Radiology.

The study found that fewer than 2.5% of the patients examined developed CIN when current guidelines emphasizing hydration were followed, according to the researchers from Radboud University Nijmegen Medical Centre in the Netherlands. The study also found that heart failure, low body mass index, and repeat contrast administration were associated with CIN.

CIN is the third most common cause of acute renal failure in hospitalized patients, and while most cases are limited to mild and transient impairment of renal function, serious morbidity and mortality, as well as longer hospital stays, can occur.

“In current practice, hydration is considered the preventive method of choice; however, evidence supporting its use is limited,” wrote Dr. Corinne Balemans and colleagues. Previous studies have relied on a variety of hydration protocols that were often used inconsistently (Radiology, June 2012, Vol. 263:3 pp. 706-713).

Balemans and colleagues aimed to determine risk factors associated with CIN by evaluating its incidence in patients with an estimated glomerular filtration rate (eGFR) of less than 60 mL/min/1.73 m2 who received iodinated contrast media intravenously and were treated using current guidelines.

Current CIN guidelines developed in Europe and the U.S. emphasize the identification of patients at high risk for CIN and the use of hydration as a preventive measure, either using normal saline or sodium bicarbonate as an alternative option, they wrote.

In the study, patients with renal insufficiency were evaluated at a special outpatient clinic where CIN was assessed and normal saline hydration was prescribed (Centraal Begeleidings Orgaan guidelines, 2007), with renal function assessed after the procedures.

The researchers stratified all patients with eGFR less than 60 mL/min/1.73 m2 for risk of CIN; those at high risk based on absolute GFR and risk factors were hydrated with 1,000 mL of isotonic saline before and after contrast injection. Serum creatinine was measured three to five days later, and CIN was defined as an increase of 25% or more from baseline. Finally, the authors recorded and compared risk factors between patients with CIN and those without using stepwise multiple logistic regression analysis.

The study included 747 patients (43% female; mean age, 71.3 years ± 10) who underwent 944 procedures. Patients were hydrated in 511 (54.1%) procedures. CIN developed after 23 procedures (2.4%).

Independent predictors of CIN were heart failure (odds ratio, 3.0), body mass index (BMI) (odds ratio, 0.9), and repeated contrast material administration (odds ratio, 2.8), Balemans and colleagues wrote. No patients needed dialysis.

The population was carefully prepared before iodinated contrast injection, and only 7.7% of patients at high risk for CIN did not receive hydration.

“Our study provides reliable estimates of CIN and shows that the incidence of CIN is low in a homogeneous population of patients with stage 3 or 4 chronic kidney disease who underwent treatment in accordance with existing guidelines and who received intravenous iodinated contrast material,” the authors wrote.

In the study, money was saved by restricting hydration to about half of the study population; patients at high risk for CIN were hydrated, whereas those at low risk were not. However, it’s possible the incidence could have been reduced further by a less restrictive policy.

Regarding heart failure, a well-known risk factor for CIN, such patients may have more severe atherosclerotic vascular disease and are more prone to hemodynamic changes during and after procedures. For them, hydration may not be helpful, the authors wrote.

The inverse association between BMI and CIN may not have been reported previously, they noted. Patients with low BMI usually have a lower percentage of muscle mass, and as a result the formulas used to calculate eGFR overestimate renal function, Balemans and colleagues wrote.

Another study reported the association between repeat contrast exposure and CIN. In that study (Trivedi and Foley), the increased risk was even notable in patients with preserved renal function.

As for study limitations, the population was large but the number of events was small. Absolute GFR was used to classify risk, and there is debate about whether GFR should be corrected for body surface area.

The incidence of CIN in patients with stage 3 or 4 chronic kidney disease is low when treated in accordance with current guidelines, the authors concluded.

“Our findings support the efficacy of hydration regimens,” they wrote. “The risk of CIN is increased in patients with heart failure, low BMI, and repeated contrast material administration. These risk factors need to be validated in future studies.”

Prevention of acute renal failure post-contrast imaging in cardiology: a randomized study..

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Abstract

BACKGROUND:

The contrast-induced nephropathy (CIN) is the third most common cause of acute renal failure (ARF) and the worsening in a pre-existing chronic renal failure (CRF), with a foreseeable increase of morbidity, mortality, length of the stay in hospital and, as a consequence, of the health costs. We studied the effectiveness of N-acetylcysteine (NAC) associated with sodium bicarbonate (Na2HCO3) infusion in order to prevent CIN in patients undergoing coronary angiography with administration of contrast medium.

MATERIALS AND METHODS:

296 patients with indication to perform coronary angiography were included in a randomized, observational study. All patients were randomly assigned to receive pre- and post-contrast hydration with 1500 ml of 0.9% saline solution infusion (Group A) or NAC (1200 mg × 2 days) + Na2HCO3 (Group B). The primary end-point was to examine CIN appearance, defined as a raise in serum values of Cr (Creatinine) ≥ 0.5 mg/dl or ≥ 25% within 24-72 hours after the exposure to the contrast medium.

RESULTS:

It has been observed a frequency of CIN of 9.4% in Gr. A compared to 7.2% in Gr. B. Nevertheless, when we put these results through a more accurate screening according to gender, degree of raise in creatinine levels and the extent of change in GFR (glomerular filtration rate), we observed a very different behaviour. In patients with normal Cr and CrCl (Clearance of Creatinine) the frequency of CIN was similar in both group A and B (approximately 5%). In patients with normal Cr but reduced ClCr the use of NAC was more effective than hydration in preventing CIN (0% vs 18% in prevalence respectively in B and A group). In patients with moderately reduced Cr and CrCl, hydration with saline solution was more effective than NAC + Na2HCO3 (8.6% vs 17.6%) while in patients with severe CRF the combined use of NAC + Na2HCO3 showed off to be very successful in preventing CIN compared to the merely hydration (0% vs 50%).

CONCLUSIONS:

In patients affected by severe CRF who are undergoing investigations with contrast medium administration, such as coronary angiography, the combined use of NAC + Na2HCO3 infusion significantly reduces the risk of developing CIN. In other circumstances the final result is related to the degree of previous GFR or creatinine values alteration or to gender. In such situations the combined use of both substances is more questionable and sometimes ineffective.

Source: Pubmed

 

N-Acetylcysteine Plus Intravenous Fluids Versus Intravenous Fluids Alone to Prevent Contrast-Induced Nephropathy in Emergency Computed Tomography.

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Abstract

STUDY OBJECTIVE:

We test the hypothesis that N-acetylcysteine plus normal saline solution is more effective than normal saline solution alone in the prevention of contrast-induced nephropathy.

METHODS:

The design was a randomized, double blind, 2-center, placebo-controlled interventional trial. Inclusion criteria were patients undergoing chest, abdominal, or pelvic computed tomography (CT) scan with intravenous contrast, older than 18 years, and at least one contrast-induced nephropathy risk factor. Exclusion criteria were end-stage renal disease, pregnancy, N-acetylcysteine allergy, or clinical instability. Intervention for the treatment group was N-acetylcysteine 3 g in 500 mL normal saline solution as an intravenous bolus and then 200 mg/hour (67 mL/hour) for up to 24 hours; and for the placebo group was 500 mL normal saline solution and then 67 mL/hour for up to 24 hours. The primary outcome was contrast-induced nephropathy, defined as an increase in creatinine level of 25% or 0.5 mg/dL, measured 48 to 72 hours after CT.

RESULTS:

The data safety and monitoring board terminated the study early for futility. Of 399 patients enrolled, 357 (89%) completed follow-up and were included. The N-acetylcysteine plus saline solution group contrast-induced nephropathy rate was 14 of 185 (7.6%) versus 12 of 172 (7.0%) in the normal saline solution only group (absolute risk difference 0.6%; 95% confidence interval -4.8% to 6.0%). The contrast-induced nephropathy rate in patients receiving less than 1 L intravenous fluids in the emergency department (ED) was 19 of 147 (12.9%) versus 7 of 210 (3.3%) for greater than 1 L intravenous fluids (difference 9.6%; 95% confidence interval 3.7% to 15.5%), a 69% risk reduction (odds ratio 0.41; 95% confidence interval 0.21 to 0.80) per liter of intravenous fluids.

CONCLUSION:

We did not find evidence of a benefit for N-acetylcysteine administration to our ED patients undergoing contrast-enhanced CT. However, we did find a significant association between volume of intravenous fluids administered and reduction in contrast-induced nephropathy.

Source: Pubmed