Consensus Report from Oncology Advisory Board Meeting

Researchers point out that the mechanisms of nephropathy due to chemotherapy and contrast medium (CM) use are similar, involving vasoconstriction, inflammation, tissue damage, and direct cytotoxic effects. Thus, it is not surprising that acute kidney injury (AKI) develops more frequently in chemotherapy recipients exposed to CM. Structures and Properties of CM y y Contrast media are tri-iodinated benzene derivatives with iodine atoms in positions 2, 4, and 6. y y Other ring positions are occupied by side chains, aimed at improving solubility, osmolality, protein binding, and tolerance. Contrast Media Profiles Many iodinated CM are available, each with its own unique profile, including pharmacological characteristics such as structure, ionicity, iodine content, viscosity, and osmolality. Pharmacokinetic Properties of CM y y Following intravenous (IV) administration, CM have a short distribution half-life (t½ d ). y y Usually, the time for the CM to distribute evenly over the fluids ranges from 2 to 30 mins. y y Plasma protein binding is approximately 1-3%. y y Patients with normal renal function can excrete approximately 100% of the CM in the first 24 h after administration. Burden of AKI in Oncology Patients – Does the Choice of Contrast Media Matter? y y In patients with decreased renal function the t½ el can increase to 40 h or more. Osmolality of CM While the viscosity and osmolality of these agents vary, all have iodine concentrations between 270 and 400 mg/ml, which is sufficient to provide adequate radiographic opacification. High-osmolar contrast media (HOCM) and low-osmolar contrast media (LOCM) are hyperosmolar to blood, whereas iso-osmolar contrast media (IOCM), such as iodixanol has same physiological osmolality as blood (290 mOSm/kg H 2 O). When a CM has a higher osmolality than blood, water can be drawn from the vascular endothelial cells, red blood cells and extravascular interstitium. Consequently, these agents may pose a significant risk in patients with low cardiac output and pulmonary congestion, as the osmotic pressure (and the amount) of contrast material may have negative effects on the volume balance in these patients. Iodixanol is isosmolar to blood and induces less fluid shift from the red blood cells (RBCs) and across the vessel walls. The net transfer of fluid from the RBCs may lead to morphological changes making them less able to bend and conform as they pass through smaller capillaries (Fig. 1). Table 1 describes the structure and properties of various CM used in radiological settings. Is Isosmolar Contrast Medium (IOCM) Better Than Low Osmolar Contrast Medium (LOCM) – Clinical Evidence A retrospective study recently compared the rates of AKI, emergent dialysis, and mortality between patients who