Choice of Iodinated Contrast MediumBarrett and Carlisle [73] reported a meta-analysis of the literature concerning the relative nephrotoxicity of highosmolality contrast media (HOCM) and low osmolality contrast media (LOCM). They concluded that LOCMare less nephrotoxic than HOCM in patients with underlying renal insufficiency. LOCM were not shown to besignificantly different in patients with normal renal function. Most centers no longer use intravascular HOCMdue to the greater incidence of various adverse effects associated with its use.Studies [74-77] have failed to establish a clear advantage of IV iso-osmolality iodixanol over IV LOCM withregard to PC-AKI or CIN. A 2009 meta-analysis using data pooled from 25 trials found no difference in the rateof PC-AKI between iodixanol and low osmolality agents after intravenous administration [78].Volume ExpansionThe major preventive action to mitigate the risk of CIN is to provide intravenous volume expansion prior tocontrast medium administration [79-85]. The ideal infusion rate and volume is unknown, but isotonic fluids arepreferred (Lactated Ringer’s or 0.9% normal saline). One possible protocol would be 0.9% saline at 100 mL/hr,beginning 6 to 12 hours before and continuing 4 to 12 hours after, but this is only practical in the inpatient setting.Oral hydration has also been utilized, but with less demonstrated effectiveness.Not all clinical studies have shown dehydration to be a major risk factor for PC-AKI. However, in the dehydratedstate, renal blood flow and GFR are decreased, the effect of iodinated contrast medium on these parameters isaccentuated, and there is a theoretical concern of prolonged tubular exposure to iodinated contrast medium dueto low tubular flow rates. Solomon et al [86] studied adult patients with chronic kidney disease who underwentcardiac angiography. The reported incidence of PC-AKI was decreased by periprocedural IV volume expansion(0.45% or 0.9% saline, 100 mL/h, 12 hours before to 12 hours after intravascular contrast mediumadministration). In another study, IV volume expansion with 0.9% saline was superior to IV volume expansionwith 0.45% saline in PC-AKI risk reduction [80].general population