Prevention of Contrast Induced Nephropathy – An Update

• administration of radiocontrast media can lead to a usually reversible form of acute kidney injury (AKI) that begins soon after the contrast is administered
• In most cases, there are no permanent sequelae, but there is some evidence that its development is associated with adverse outcomes

Overview:

1. The use of lower doses of contrast and avoidance of repetitive studies that are closely spaced (within 48 to 72 hours)
2. Avoidance of volume depletion or nonsteroidal anti-inflammatory drugs (NSAIDs), both of which can increase renal vasoconstriction.
3. IV saline or sodium bicarbonate.
4. Acetylcysteine.
5. use of selected low- or iso-osmolal nonionic contrast agents

IV Saline

• Optimal choice of solution, administration and duration is unclear
• Volume expansion with isotonic saline may be superior to one-half isotonic saline

IV Bicarbonate

• Alkalinization may protect against free radical injury
• Variations in outcomes with sodium bicarbonate may be due to the significant heterogeneity found in these studies
• In general, studies that have shown Na Bicarbonate to be either equivalent or better outcomes compared to NS
• a recent meta analysis showed it is effective in preventing CIN among patients with pre-existing renal insufficiency. However, it fails to lower the risks of dialysis and mortality and therefore cannot improve the clinical prognosis of patients with CIN.
•  no available isotonic bicarbonate product - a solution can be prepared by adding 150 mEq of sodium bicarbonate (three 50 mL ampules of 1 mEq/mL sodium bicarbonate) to 850 mL of sterile water
• One regimen is to administer a bolus of 3 mL/kg of isotonic bicarbonate for 1H prior to the procedure and continued at a rate of 1 mL/kg per hour for 6H after the procedure. 
• An alternative regimen is to administer 1 mL/kg for 6 to 12 hours pre- and postprocedure
• Although the administration of sodium bicarbonate may be potentially superior to NS, the 2012 KDIGO guideline work group did not make a specific recommendation for the use of bicarbonate preferentially to saline due to concern for potential harm from errors in compounding

Acetylcysteine

• possible mechanism of benefit in contrast-induced nephropathy involves minimizing both vasoconstriction and oxygen-free radical generation
• Given the conflicting data regarding benefit, we cannot make a strong recommendation regarding the use of acetylcysteine
• Since the agent is potentially beneficial, well tolerated, and relatively inexpensive, the 2012 KDIGO guidelines that suggest administration of acetylcysteine to patients at high risk
• The joint ACC/AHA guidelines do not recommend acetylcysteine
• This must be accompanied by intravenous isotonic fluid administration and use of a low- or iso-osmolal contrast agent
• Oral dosing is preferred over the IV (Based upon the lack of convincing evidence of benefit and the potential risk of anaphylactoid reactions)

Summary

1. Isotonic intravenous fluids prior to and continued for several hours after contrast administration
2. The optimal type of fluid and timing of administration are not well established. We suggest isotonic bicarbonate rather than isotonic saline 
3. Despite conflicting data, we suggest that acetylcysteine be administered the day before and the day of the procedure, based upon its potential for benefit and low toxicity and cost 
4. Based upon the lack of convincing evidence of benefit and the potential risk of anaphylactoid reactions, we suggest not using intravenousacetylcysteine

Reference:

1. www.uptodate.com
2. The efficacy of sodium bicarbonate in preventing contrast-induced nephropathy in patients with pre-existing renal insufficiency: a meta-analysis. http://bmjopen.bmj.com/content/5/3/e006989.full