[Contrast induced nephropathy]

Abstract

Contrast media induced nephropathy is a common complication, particularly in high risk patients, such as patients with chronic kidney disease (CKD) and diabetes. The majority of studies show an increased in-hospital mortality and an unfavourable long-term prognosis after manifestation of contrast media induced nephropathy. The course and the potential risk factors of this type of acute renal failure are known. Therefore, an effective prophylaxis should allow to prevent this complication. In low risk patients oral or intravenous volume expansion is probably sufficient combined with the withdrawal of non-steroidal anti-inflammatory drugs. In high risk patients additional prophylactic measures are needed but their efficacy is not clearly defined. Therefore, heterogeneous recommendations exist. Hydration reduces (afferent) renovasoconstriction, the tubuloglomerular feedback, the tubulotoxic effects of contrast media (via dilution) and the oxygen radical formation. The optimal composition, timing and amount of fluid which should be administered to the patients remain unclear. Most studies show that intravenous administration of volume is more effective than oral fluid intake. The majority of studies found a benefit of isotonic sodium bicarbonate in comparison to isotonic saline solutions, even if meta-analyses displayed only a positive trend for sodium bicarbionate due to the heterogeneity of the data. Controversies exist for N-acetylcysteine, vitamin C, fenoldopam, theophylline or statins. Due to low cost and low side effects, N-Acetylcysteine is widely used. Theophyllin (given intravenously 30 minutes before contrast media injection) is renoprotective, particularly in intensive care unit patients. Very important is the reduction of contrast media volume (if possible <30 ml for diagnostic procedures and <100 ml for interventions). Iso-osmolar and low-osmolar contrast media may have a comparable low risk for the induction of contrast media induced nephropathy. This risk is probably higher after intra-arterial as compared to intravenous administration of contrast media. Controversies exist with respect to the reduction of contrast media induced nephropathy and mortality by prophylactic hemodialysis or hemofiltration. A possible benefit of these procedures consists probably for patients with advanced chronic kidney disease (stage 5). With the further increase of investigations using contrast media, with the further increase in vascular interventions, in age and comorbidities of the patients one may suggest that the problem of contrast media induced nephropathy will further increase, despite all prophylactic procedures so far recommended.