The Effect of Acetylcysteine and Ascorbic Acid on the Prevention of Radiographic-contrast-agent Induced Reduction in Renal Function in ICU Patients.

Introduction: Administration of radiographic contrast agents often result in a reversible acute reduction in renal function that begins soon after contrast dye administration.

The incidence of contrast induced nephropathy varies from 5% to 50% depending on the patients' population and the criteria for contrast induced nephropathy (CIN), definition used and it is considered as one of the leading causes of hospital acquired acute renal failure.

The pathogenesis of contrast-induced nephropathy is uncertain. There are two main theories. According to the first one a possible influence on renal hemodynamics, mainly vasoconstriction, resulting in medullary ischemia possibly mediated by an alteration in endothelin and adenosine. In addition to direct vasoconstriction of renal vessels, iodinated contrast agents also block an important pathway for vasodilation and autoregulation possibly by reducing the production of nitric oxide. And according to the other main theory contrast agents exert direct toxic effects on tubular epithelial cells. It seems that reactive oxygen species have a role in CIN.

A lot of studies had examined the incidence of contrast agent-associated nephrotoxicity mainly in stable patients undergoing elective radiographic procedures.

Numerous agents have been examined for their ability to prevent contrast-induced decreases in renal function. Among them the use of low-osmolarity, non anionic contrast agents, and prophylactic hydration have reduced the incidence of CIN. Administration of drugs such as calcium antagonists, theophyllin, dopamine and atrial natriuretic peptide does not prevent CIN. In some studies antioxidant agents like acetylcysteine and ascorbic acid seem to reduce the incidence of CIN.