How can contrast-induced nephropathy be prevented and treated in patients with impaired renal function?

From the Guidelines

Preventing contrast-induced nephropathy (CIN) in patients with impaired renal function requires a multifaceted approach focusing on hydration, medication management, and contrast minimization, with the most recent and highest quality study 1 suggesting that attempts to minimize the risk of contrast nephropathy should be made through the avoidance of nephrotoxic agents, use of adequate hydration before the administration of iodinated contrast-agent, and minimization of the volume of contrast media.

Key Recommendations

• Hydration: Intravenous isotonic saline (0.9% sodium chloride) should be administered at 1-1.5 mL/kg/hour for 6-12 hours before and after contrast exposure, as supported by 1 and 1.
• Medication management: Nephrotoxic medications such as NSAIDs, aminoglycosides, and ACE inhibitors should be temporarily discontinued 48 hours before the procedure.
• Contrast minimization: The contrast volume should be minimized, ideally keeping the ratio of contrast volume (in mL) to eGFR below 3, as suggested by 1 and 1.
• Contrast agents: Low or iso-osmolar contrast agents are preferred over high-osmolar agents, as recommended by 1 and 1.
• N-acetylcysteine: The use of N-acetylcysteine is not supported by recent high-quality studies, including 1, which found no benefit in preventing contrast-induced AKI.

Treatment of Established CIN

• Continued hydration, close monitoring of renal function and electrolytes, and supportive care are essential, as suggested by 1 and 1.
• Dialysis is rarely needed but may be considered in severe cases with significant fluid overload or electrolyte disturbances.

Rationale

These preventive measures work by maintaining renal perfusion, reducing contrast concentration in the tubules, preventing direct tubular toxicity, and mitigating oxidative stress that contributes to kidney injury, as supported by the studies cited above.

From the Research

Prevention of Contrast-Induced Nephropathy

• Identification of patients at risk is crucial, using methods such as patient questionnaires, review of medical history, and measurement of serum creatinine levels prior to the administration of contrast media (CM) 2.
• Estimation of the glomerular filtration rate (GFR) before CM administration is recommended to assess renal function 2.
• Patients should be well-hydrated, and nephrotoxic medications should be withdrawn at least 24 hours prior to CM administration 2.
• Use of the minimal necessary CM dose is recommended, as the nephrotoxic effect of CM is dose-dependent 2.
• Appropriate selection of CM is important, with iso-osmolar CM being preferred over low-osmolar CM in patients with renal insufficiency and diabetes 2.

Treatment of Contrast-Induced Nephropathy

• Saline hydration and use of non-ionic isosmolar contrast media can reduce the incidence of contrast-induced nephropathy 3.
• N-acetylcysteine has not been consistently shown to reduce the incidence of contrast-induced nephropathy, with conflicting results in different studies 3, 4.
• Other pharmacological interventions, such as calcium channel blockers, dopamine, and theophylline, have not been proven to be effective in preventing contrast-induced nephropathy 4, 5.
• Haemofiltration for several hours before and after contrast medium injection may offer good protection against contrast media nephrotoxicity in patients with advanced renal disease 5.

Risk Factors for Contrast-Induced Nephropathy

• Pre-existing renal insufficiency, diabetes, advanced age, congestive heart failure, and dehydration are common risk factors for contrast-induced nephropathy 2, 6.
• Patients with these risk factors should be carefully selected and monitored, and preventive strategies should be implemented to minimize the risk of contrast-induced nephropathy 6.