How to prevent contrast-induced acute kidney injury (AKI) in at-risk patients?

Prevention of Contrast-Induced Acute Kidney Injury in At-Risk Patients

Intravenous volume expansion with isotonic fluids is the cornerstone of prevention for contrast-induced acute kidney injury (CI-AKI) in at-risk patients, along with using the lowest possible dose of either iso-osmolar or low-osmolar contrast media. 1, 2

Risk Assessment

• Screen all patients for risk factors before administering intravascular iodinated contrast media, particularly focusing on pre-existing impaired kidney function (eGFR <60 mL/min/1.73m²), diabetes mellitus, advanced age, heart failure, and anticipated high contrast volume 2, 3
• Identify at-risk patients through serum creatinine measurement to estimate glomerular filtration rate, ideally before scheduling the procedure 4
• Consider alternative imaging methods in patients at increased risk for CI-AKI when possible 1

Preventive Strategies

Hydration Protocol

• Administer IV volume expansion with isotonic fluids (either normal saline or sodium bicarbonate) rather than no volume expansion in at-risk patients 1, 2
• Recommended hydration protocol: 1 mL/kg/hour for 12 hours before and continued for 24 hours after the procedure 2
• Reduce hydration rate to 0.5 mL/kg/hour if ejection fraction <35% or NYHA heart failure class >2 2
• Oral hydration alone is insufficient for high-risk patients 2, 5

Contrast Media Selection

• Use either iso-osmolar or low-osmolar iodinated contrast media rather than high-osmolar contrast media 1, 2
• No consistent differences in CI-AKI risk have been demonstrated between iso-osmolar and low-osmolar contrast agents in subsequent trials, despite earlier studies suggesting benefits of iso-osmolar agents 1
• Use the lowest possible dose of contrast medium to achieve diagnostic results 1, 2, 3

Additional Considerations

• Consider temporarily discontinuing nephrotoxic medications 48 hours before contrast administration 2
• N-acetylcysteine (NAC) has shown inconsistent results in preventing CI-AKI 1, 2, 5
  • The largest randomized trial (ACT) showed identical CI-AKI incidence (12.7%) in both NAC and control groups 1, 3
  • If using NAC, administer it together with IV isotonic crystalloids, not as a standalone prevention strategy 1
• Avoid prophylactic hemodialysis or hemofiltration solely for contrast removal in at-risk patients 1, 2, 5

Special Considerations

• For patients undergoing cardiac procedures, the risk of CI-AKI should be balanced against the potential benefits of the diagnostic or therapeutic intervention 1
• In very high-risk patients (stage 4-5 CKD), prophylactic hemofiltration may be considered before complex interventions, though evidence is limited 3
• Theophylline is not recommended for CI-AKI prevention 1, 6
• The risk of CI-AKI from IV contrast for CT scans may be lower than traditionally assumed, particularly in patients with normal renal function 7

Common Pitfalls to Avoid

• Failing to identify high-risk patients before procedures 3
• Relying solely on pharmacological approaches (like NAC) without proper hydration 2, 5
• Using oral fluids alone in high-risk patients 1, 2
• Administering excessive contrast volume when a lower dose would be sufficient 2, 8
• Delaying necessary contrast procedures in emergency situations due to fear of CI-AKI 1