Contrast induced nephropathy is one of the common complications of various diagnostic and therapeutic angiographic procedures. It results due to administration of contrast media. It is the third most common cause of hospital acquired acute renal injury which constitutes up to 12% of the cases in the US . Treatment of contrast induced nephropathy is currently limited to management of fluid and electrolyte imbalances and by dialysis in severe cases. The limited treatment options make prevention of contrast induced nephropathy cornerstone of management.
Contrast-induced nephropathy (CIN) is defined as the impairment of kidney function 48-72 hours after intravenous contrast administration. The impairment is measured as either a 25% increase in serum creatinine (SCr) from baseline or a 0.5 mg/dL (44 µmol/L) increase in absolute Serum Creatinine value .
Steps to be taken for Prevention of Contrast Induced Nephropathy
The following steps should be taken for prevention of contrast induced nephropathy before an angiographic procedure :
- Basic renal function tests (namely, glomerular filtration rate [GFR] and serum creatinine) to be done for all cases before hand
- Screening for potential nephrotoxic drugs should be done for every patient undergoing an angiography
- Identification of high-risk patients: High risk patients should be identified by taking their past history. Patient should be asked for preexisting impaired renal function (baseline GFR < 60 mL/ min) or other comorbid conditions, such as diabetes, congestive heart failure, and hypertension. The rates of contrast-induced nephropathy (CIN) in those high-risk patient groups can be as high as 10 to 26%.
- Stopping Metformin: All patients with diabetes who take metformin should have the drug discontinued for at least 24 hours (or 48 hours in patients with abnormal renal function) prior to contrast media administration to decrease the risk of developing lactic acidosis, which can occur if acute kidney injury develops. Metformin can be restarted 48 hours after the administration of contrast media.
- Stopping other Nephrotoxic Drugs: Other nephrotoxic drugs, such as nonsteroidal antiinflammatory agents and angiotensin-converting enzyme (ACE) inhibitors, are potentially nephrotoxic and should be discontinued prior to contrast administration.
- Avoid Volume Depletion and Aggressive Periprocedural Hydration: The CIN Consensus Working Panel recommends intravenous (IV) hydration with isotonic 0.9% saline at the rate of 1.0 to 1.5 mL/kg/h for 3 to 12 hours before and for 6 to 24 hours in high-risk patients.
- Role of IV Sodium Bicarbonate and N-acetylcysteine in CIN prevention: The role of IV Sodium Bicarbonate and N-acetylcysteine in CIN prevention is still controversial with no strong evidence supporting their routine usage.
Treatment of CIN
There is a decrease of renal perfusion for up to 20 hours following contrast administration. Intravascular volume expansion is one of the first and most important treatment options. It maintains renal blood flow, preserves nitric oxide production, prevents medullary hypoxemia, and enhances contrast elimination .
A number of other treatments for Contrast Induced Nephropathy have been investigated, including the following:
- Sodium bicarbonate
- N-acetylcysteine (NAC)
- Ascorbic acid
- The adenosine antagonists theophylline and aminophylline
- Forced diuresis
- Renal replacement therapy
- Prostaglandin E1
On systematic review and meta-analysis of prevention strategies for Contrast Induced Nephropathy following were found to have statistically significant benefit :
- Low-dose NAC: Risk ratio (RR), 0.75
- NAC, in patients receiving low-osmolar contrast media: RR, 0.69
- Statins plus NAC (versus NAC plus IV saline): RR, 0.52
Renal replacement therapy is required in fewer than 1% of normal patients with CIN and in up to 3.1% in patients with underlying renal impairment .
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 Perrin T, Descombes E, Cook S. Contrast-induced nephropathy in invasive cardiology. Swiss Med Wkly. 2012;142:w13608. [PubMed]
 Subramaniam RM, Suarez-Cuervo C, Wilson RF, et al. Effectiveness of prevention strategies for contrast-induced nephropathy: a systematic review and meta-analysis. Ann Intern Med. 2016 Mar 15. 164(6):406-16. [QxMD MEDLINE Link].