Update: Prevention of contrast-induced nephropathy in the emergency department.

STUDY OBJECTIVE Some studies have suggested that there exist therapies that can prevent contrast-induced nephropathy, which are practical in an emergency setting. This evidence-based emergency medicine (EBEM) critical appraisal reviews the literature, including additional studies appearing since the publication of an earlier EBEM review in 2007. METHODS The updated search for randomized controlled trials from 2006 to 2008 complemented the previous search from 1966 to 2005. The methodological quality of the studies was assessed. Qualitative methods were used to summarize the study results. RESULTS The search identified 2 studies not included in the previously published review of prophylactic therapies against contrast-induced nephropathy, yielding a total of 4 blinded, randomized, placebo-controlled trials involving bicarbonate and ascorbic acid. The present study of bicarbonate found a similar benefit as the previously reviewed bicarbonate trial. The early termination of both bicarbonate studies presents significant analytical concerns. The present study of ascorbic acid failed to reproduce the prophylactic effect of ascorbic acid observed in the previously reviewed trial. This difference in outcomes of the 2 ascorbic acid trials is related to variations in the volume of contrast and procedural hydration between the studies. CONCLUSION Although bicarbonate should still be considered a low-risk prophylactic agent, it appears that other factors (type of contrast agent, volume of contrast, and procedural hydration protocol) have an important influence on the risk of contrast-induced nephropathy. For the emergency physician, limiting exposure to contrast agents and adequate precontrast hydration are still the first line of defense against contrast-induced nephropathy.