CONTRAST NEPHROPATHY PROPHYLAXIS

Nephropathy due to contrast medium is defined as impairment in renal function occurring within 72 hours of contrast medium being administered. It is characterised by renal vasoconstriction and avid sodium retention.

It accounts for approximately 12% of hospital acquired acute renal failure (the third commonest cause of hospital acquired acute renal failure), and 7 % cases need dialysis

Risk factors for the development of contrast nephropathy include:
 

• Pre-existing renal insufficiency (most important risk factor) 
• Diabetes mellitus 
  Age > 75 years
• Concurrent use of nephrotoxic drugs (NSAIDS, aminoglycosides, metformin)
• Dehydration 
• Hypotension
• Heart failure 
• Cirrhosis 
• Nephrotic syndrome 
• Hypertension

 
Suggested protocol for managing potential contrast nephropathy:

1. Consider prophylaxis in all patients with eGFR < 50 mL/min

2. Avoid nephrotoxic drugs for 24 hours pre-procedure (metformin for 48 hours)
 

3. Measure creatinine pre-procedure, at 24 and 48 hours post-procedure
 

4. Give normal saline 1 mL/kg/hour 12 hours pre and 12 hours post-procedure

Author: Dr J Taylor Number: 0319.3 Publication Date: Apr 07 Review Date: Apr 08 N.B. Paper copies maybe out of date

5. In high-risk cases (eGFR < 30 mL/min, and/or large contrast load e.g. coronary angiogram), use N-acetylcysteine in addition to saline rehydration.
 

6. Use iso-osmolar contrast medium (Aspelin P et al, N Engl J Med 2003; 348: 491 – 9)

Protocol for N-acetylcysteine administration (Marenzi G et al N Engl J Med 2006; 354:2773 – 82):

 
1200mg IV pre-procedure
 

1200mg bd PO for 48 hours post-procedure
 

IV bolus 1200mg = 6mL of 200mg/mL vial in 100 mL normal saline over 30 minutes

Oral N-acetylcysteine = oral administration of 6 mL of IV solution undiluted

One study has suggested that 1.26% sodium bicarbonate hydration (3mL/kg/hour for 1 hour pre-procedure followed by 1ml/kg/hour for 6 hours post-procedure) may be more effective than saline rehydration (Merten G et al JAMA 2004; 291: 2328 – 2334), but this requires further study for confirmation.