ontrast medium-induced nephropathy (CIN) is a common cause of acute renal dysfunction. During the past few years, several publications have provided clinical and experimental data on this topic. Our review focuses on 4 major concerns of CIN relevant in clinical practice: (1) What is the evidence that CIN is a clinically relevant and a dangerous condition for the patient? (2) Is there a difference in CIN rate among different contrast media, and how is that related to the physicochemical properties of different available contrast media? (3) What is the evidence that periprocedural hydration is an effective, appropriate, and safe method to prevent CIN? (4) What is the evidence for the use of a drug, in particular acetylcysteine, to prevent CIN?
Clinical RelevanceCIN has gained increased attention in the clinical setting, particularly during cardiac intervention but also in many other radiological procedures in which iodinated contrast media are used. There is at present good clinical evidence from well-controlled randomized studies that CIN is a common cause of acute renal dysfunction. 1,2 CIN is the acute deterioration of renal function after parenteral administration of radiocontrast media in the absence of other causes. CIN is generally defined as an increase in serum creatinine concentration of Ͼ0.5 mg/dL (Ͼ44 mol/L) or 25% above baseline within 48 hours after contrast administration. [3][4][5][6][7] Although the exact mechanisms of CIN have yet to be fully elucidated, several causes have been described. Increased adenosine-, endothelin-, and free radical-induced vasoconstriction and reduced nitric oxide-and prostaglandin-induced vasodilatation have been observed. These mechanisms cause ischemia in the deeper portion of the outer medulla, an area with high oxygen requirements and remote from the vasa recta supplying the renal medulla with blood. Contrast agents also have direct toxic effects on renal tubular cells, causing vacuolization, altered mitochondrial function, and apoptosis. 8 Atopy does not play a role in the pathogenesis of CIN.The incidence of CIN in the general population has been calculated to be Ͻ2%. In high-risk patients, ie, patients with chronic renal impairment, diabetes mellitus, congestive heart failure, and older age, the incidence has been calculated to be Ͼ20% to 30%. 3-7 CIN has been associated with increased morbidity, extended length of hospital stay, and increased costs. 9 Several risk factors have been described for CIN. 10 -12 A risk score for prediction of CIN after percutaneous coronary intervention has been reported by Mehran et al. 12 That risk score includes hypotension (5 points, if systolic blood pressure Ͻ80 mm Hg for at least 1 hour requiring inotropic support), use of intra-aortic balloon pump (5 points), congestive heart failure (5 points, if class III/IV by New York Heart Association classification or history of pulmonary edema), age (4 points, if Ͼ75 years), anemia (3 points, if hematocrit Ͻ39% for men and Ͻ36% for women), diabetes mellitus (3 points), contrast media...