Prevention of Contrast-Induced Nephropathy
Intravenous hydration with isotonic saline (1.0-1.5 mL/kg/hour) starting 3-12 hours before and continuing 6-24 hours after contrast exposure is the cornerstone of CIN prevention, while N-acetylcysteine should NOT be used as it provides no benefit. 1
Risk Stratification
Before any contrast procedure, identify high-risk patients by evaluating the following factors:
- Pre-existing chronic kidney disease, especially eGFR <60 mL/min/1.73 m² (most critical when <40 mL/min/1.73 m²) 1, 2
- Diabetes mellitus 1
- Congestive heart failure 1
- Advanced age 1
- Anemia and left ventricular systolic dysfunction 1
- Emergency procedures 1
Mandatory Prevention Strategies
Hydration Protocol (Class I Recommendation)
Standard protocol: Administer isotonic saline (0.9% NaCl) at 1.0-1.5 mL/kg/hour for 3-12 hours before and 6-24 hours after contrast exposure 1. This is the single most effective intervention and must be coordinated with radiology/angiography scheduling 3.
For severe renal insufficiency (eGFR <30 mL/min/1.73 m²): Increase fluid replacement rate to 1000 mL/hour without negative fluid balance, and continue saline hydration for 24 hours after the procedure 1.
Alternative option: Sodium bicarbonate (154 mEq/L in dextrose and water) at 3 mL/kg for 1 hour before contrast, followed by 1 mL/kg/hour for 6 hours after the procedure may be considered, though recent evidence shows no superiority over normal saline 3, 1.
Contrast Media Selection (Class I Recommendation)
- Use low-osmolar or iso-osmolar contrast media in all high-risk patients 1
- Minimize contrast volume to <350 mL or <4 mL/kg, or maintain total volume/eGFR ratio <3.4 1
Statin Therapy (Class IIa Recommendation)
Consider short-term high-dose statin therapy: rosuvastatin 40/20 mg, atorvastatin 80 mg, or simvastatin 80 mg 1.
What NOT to Do
N-Acetylcysteine (NAC) - Class III Recommendation
Do not use NAC for CIN prevention. 1 The landmark ACT trial (2,308 patients) demonstrated identical CIN incidence (12.7%) in both NAC and control groups, with no difference in mortality or dialysis requirement 3. Meta-analysis of high-quality trials confirmed no benefit (RR 1.05; 95% CI 0.73-1.53) 3. The apparent benefits in earlier studies were confined to trials with high risk of bias 3.
Other Non-Recommended Interventions
- Do not use sodium bicarbonate as a substitute for standard saline hydration (Class III, Level A) 1
- Do not perform prophylactic hemodialysis in patients with stage 3 CKD 1
- Avoid nephrotoxic medications (NSAIDs, aminoglycosides) peri-procedurally 2, 4
- Withhold metformin for at least 48 hours and until renal function is reassessed 2
Special Considerations
Very High-Risk Patients Unable to Receive Pre-Hydration
When prophylactic hydration cannot be performed, consider furosemide with matched hydration: initial bolus of 250 mL saline over 30 minutes, followed by furosemide 0.25-0.5 mg/kg IV, with fluid replacement matched to urinary output 1.
Stage 4-5 CKD Undergoing Complex Interventions
Prophylactic hemofiltration may be considered (Class IIb recommendation), though this is reserved for the highest-risk scenarios 1.
Post-Procedure Monitoring
- Measure serum creatinine at 48-96 hours post-contrast to capture the typical window for CIN development 5
- Continue withholding nephrotoxic medications (metformin, NSAIDs) until renal function returns to baseline 2
- Monitor for volume overload, particularly in patients with heart failure 5
Common Pitfalls
The most critical error is failure to identify high-risk patients before procedures, particularly those with pre-existing renal dysfunction 1. CIN occurs in up to 15% of patients with chronic renal dysfunction and can lead to hemodialysis requirement in 0.5-12% of cases, with potential progression to end-stage renal failure 3, 1. The coordination of hydration protocols with diagnostic imaging can be challenging but is essential 3. Normal saline is preferred in Canada due to broad availability and lower cost compared to sodium bicarbonate 3.