What is the risk of contrast-induced neuropathy in a patient with impaired renal function (GFR of 25) undergoing a Computed Tomography (CT) angiogram?

From the Guidelines

For a patient with a GFR of 25 undergoing CT angiogram with contrast, the risk of contrast-induced nephropathy (CIN) is high, and preventive measures should be implemented to minimize this risk. The patient's low GFR indicates severe chronic kidney disease (CKD), which is a major risk factor for CIN. According to the 2014 ESC/EACTS guidelines on myocardial revascularization 1, patients with moderate-to-severe CKD should receive hydration with isotonic saline, and the use of low-osmolar or iso-osmolar contrast media is recommended.

The guidelines suggest the following preventive measures:

• Hydration with isotonic saline at a rate of 1.0 to 1.5 mL/kg per hour for 3 to 12 hours before and continuing for 6 to 24 hours after the procedure, as recommended by the 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention 1
• Using the lowest possible dose of iso-osmolar or low-osmolar contrast media, with a total contrast volume/GFR < 3.4, as recommended by the 2014 ESC/EACTS guidelines 1
• Temporarily discontinuing nephrotoxic medications like NSAIDs and metformin 48 hours before the procedure
• Considering short-term, high-dose statin therapy, such as rosuvastatin 40/20 mg or atorvastatin 80 mg, as recommended by the 2014 ESC/EACTS guidelines 1

The use of N-acetylcysteine is not recommended as a preventive measure for CIN, as stated in the 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention 1 and the 2014 ESC/EACTS guidelines on myocardial revascularization 1. The risk of CIN in this patient is approximately 20-50%, with CIN typically manifesting as a rise in serum creatinine 24-72 hours post-procedure. Renal function should be monitored by checking serum creatinine 48-72 hours after the procedure, and the patient should be advised to maintain good hydration.

Key points to consider:

• The patient's severe CKD increases the risk of CIN
• Hydration with isotonic saline and minimizing contrast media volume are crucial preventive measures
• The use of low-osmolar or iso-osmolar contrast media is recommended
• N-acetylcysteine is not recommended as a preventive measure for CIN
• Renal function should be closely monitored after the procedure.

From the FDA Drug Label

5.3 Contrast-Induced Acute Kidney Injury Acute kidney injury, including renal failure, may occur after iodixanol administration Risk factors include: pre-existing renal impairment, dehydration, diabetes mellitus, congestive heart failure, advanced vascular disease, elderly age, concomitant use of nephrotoxic or diuretic medications, multiple myeloma/paraproteinaceous diseases, repetitive and/or large doses of an iodinated contrast agent.

The FDA drug label does not mention contrast-induced neuropathy as a risk associated with iodixanol administration in patients with a GFR of 25. However, it does mention the risk of contrast-induced acute kidney injury, which may be relevant for patients with pre-existing renal impairment.

• Key risk factors for contrast-induced acute kidney injury include pre-existing renal impairment, which is present in this patient with a GFR of 25.
• The label recommends using the lowest necessary dose of iodixanol in patients with renal impairment and adequately hydrating patients prior to and following administration 2.

From the Research

Risk of Contrast-Induced Nephropathy in CT Angiogram

• The risk of contrast-induced nephropathy (CIN) in patients with a glomerular filtration rate (GFR) of 25 is a significant concern 3.
• A study published in 2018 found that patients with a GFR of less than 30 mL/min/1.73m² are at high risk of CIN, with an incidence of 13.6% 3.
• Another study published in 2007 found that the use of low or iso-osmolar contrast agents, such as iodixanol, can minimize the risk of CIN in patients with renal impairment 4, 5.
• However, the same study found that even with the use of low or iso-osmolar contrast agents, patients with a GFR of less than 30 mL/min/1.73m² are still at risk of CIN 5.
• A multicenter observational study published in 2010 found that the incidence of CIN in patients undergoing computed tomography (CT) procedures with iodixanol-enhanced CT protocols was 2.6%, with a higher incidence of 4.7% in patients with renal impairment 6.

Prevention of Contrast-Induced Nephropathy

• The cornerstone of CIN prevention is adequate parenteral volume repletion 4.
• The use of prophylactic intravenous hydration can mitigate the risk of CIN, but the risk of complications of prophylactic intravenous hydration should not outweigh the positive preventive effect 3.
• Withholding potentially nephrotoxic medications and considering the use of N-acetylcysteine may also be beneficial in preventing CIN 4.

Contrast-Induced Neuropathy

• There is limited information available on the risk of contrast-induced neuropathy in patients undergoing CT angiogram with a GFR of 25.
• However, it is essential to note that contrast-induced neuropathy is a rare but potential complication of contrast agent administration 7.