Contrast-induced nephropathy

A 55-year-old man requires cerebral angiography and possible coiling of a large basilar aneurysm. He is diabetic with impaired renal function. Which of the following has been shown to reduce most the chances of the patient developing a contrast-induced nephropathy (CIN)?

a) An infusion of isotonic sodium bicarbonate commenced prior to contrast infusion

b) An N-acetylcysteine infusion commenced prior to contrast infusion

c) The use of the lowest dose of an iso-osmolar contrast medium possible

d) Commencement of an aminophylline infusion prior to contrast infusion

e) An infusion of 0.9% sodium chloride commenced prior to contrast infusion

Answer: e

Explanation

Contrast-induced nephropathy (CIN) is among the commonest causes of hospital-acquired

acute renal failure. There are a number of factors variably associated with increased rates of CIN including diabetes, age over 75 years, peri-procedure volume depletion, heart failure, cirrhosis or nephrosis, hypertension, proteinuria, concomitant use of non-steroidal anti-inflammatory drugs, and intra-arterial injection of contrast medium. High doses of contrast medium also increase the likelihood of renal dysfunction. The risk of a decline in kidney function after the administration of contrast medium rises exponentially with the number of risk factors present. Contrast-induced nephropathy is usually transient, with serum creatinine levels peaking at three days after administration of the medium and returning to baseline within ten days. A decline in kidney function after the administration of a contrast medium is associated with a prolonged hospital stay, adverse cardiac events, and high mortality both in the hospital and in the long term. However, the association between these outcomes and the decline in function may be explained, at least in part, by coexisting conditions, the severity of the acute illness and other causes of acute kidney failure. The pathogenesis of CIN in humans is not clear, but is probably related to a combination of toxic injury to the renal tubules and ischaemic injury partly mediated by reactive oxygen species. A large number of treatments have been tried to reduce the incidence of CIN. Of these there is clear evidence for peri-procedure infusion of 0.9% saline solution and the use of the smallest dose possible of a low osmolality contrast medium. The evidence for N-acetylcysteine, isotonic sodium bicarbonate or aminophylline infusions is equivocal and further data is needed on the benefits of iso-osmolar contrast media.

Reference

Barrett BJ, Parfrey PS. Clinical practice. Preventing nephropathy induced by contrast

medium. N Engl J Med 2006; 354(4): 379–86.