Content area
Full Text
In the second of her articles on iodinated contrast agents, Gill Marshall focuses now on induced nephrotoxicity and why it is an increasing problem.
Introduction
As radiographers' roles extend and you increasingly perform delegated medical tasks, such as contrast agent injection under written schemes of work, it is essential that you understand these agents, their possible adverse effects and how such effects can be minimised. This is vital for both the safety of patients and the continuous professional development of radiographers.
Having considered the state of the art in iodinated contrast agents in last month's article, we now turn our attention to contrast agent induced nephrotoxicity (CIN) and why it is an increasing clinical problem. Reading the first article may enhance your understanding of various terms used in this article.
The annual sale of contrast agents now represents 60 million doses and CIN is known to be the third leading cause of hospital-acquired acute renal failure (ARF)1-3. Whilst the incidence of nephropathy is less than 2% in the general population4, in patients with increased risk this rises to 12-50%5-7. In patients with good renal function, the choice of contrast agent seems to have little effect on the development of CIN8, but this is not so in high risk patients7,11.
ARF is the rapid deterioration in kidney function that results in the failure of the kidney to excrete nitrogenous wastes and to maintain fluid and electrolyte homeostasis". ARF, induced by contrast agents, is defined as a greater than 25% increase in serum creatinine or a serum creatinine value of above 44µmol/L (0.5mg/dl), occurring less than 72 hours after contrast agent injection13,14. Typically, creatinine levels increase within 48 hours and then start to decrease by day3. Complete recovery occurs in 10-14 days13 and diuresis is usually maintained. Dialysis is rarely needed and if so these are high risk patients.
So whilst CIN is generally benign, it causes an increase in mortality between 3.8% and 64% depending on the increase in the creatinine concentration2, and patients experiencing CIN have a much worse outcome than patients without CIN15,16. Consequently, as the use of iodinated agents increases with higher volumes and concentrations in sicker patients, CIN is a growing clinical crisis12.
Pathogenesis of CIN17-19
The injection of contrast...