Principles regarding contrast media utilization and associated adverse events are generally similar between children and adults. This section will address specific areas in which pediatric use of contrast material differs from adult use and attempt to avoid repeating recommendations that are similar for both patient populations. contrast media. As viscosity increases, the pressure associated with IV contrast medium injection increases. This physical property is especially important for pediatric patients due to the use of small gauge angiocatheters in tiny blood vessels. Contrast medium viscosity and angiocatheter size are important factors in determining maximum injection rates. If a rapid injection rate is desired through a small angiocatheter and contrast medium viscosity is high, two problems can potentially result. First, the desired injection flow rate may not be achieved. Second, high pressure may cause catheter failure and vessel injury. There is distinct variation in viscosity between different contrast agents (see Appendix A). Additionally, contrast medium viscosity is not directly proportional to the concentration of iodine. Using iopamidol (Isovue) as an example, at body temperature, viscosity increases from 2.0 centipoise (cps) at 200 mg/ml to 9.4 cps at 370 mg/ml at body temperature. Viscosity of contrast media is affected by temperature (see Appendix A). As temperature increases, viscosity decreases allowing for increased flow rates at lower pressures. A study by Vergara and Seguel  that included both adult and pediatric patients showed that warming contrast media resulted in fewer adverse events following injection when compared to contrast media administered at room temperature. Other Unique Issues in Children Several additional issues complicate the administration of IV contrast media to neonates and children, including the use of small volumes of contrast medium, the use of small gauge angiocatheters, and unusual vascular access sites. First, very small volumes of contrast media are typically administered to neonates and infants (typically 2 ml/kg). As a result, timing of image acquisition with regard to contrast medium administration may be important when performing certain imaging studies, such as computed tomography (CT) angiography. A
Iodinated Intravascular Contrast Media Unique Considerations in Children Contrast Agent Osmolality Osmolality is an important physical property of contrast media. A variety of the adverse effects attributed to intravascularly administered iodinated contrast agents seem to be related, at least in part, to this physical property, including physiologic side effects, allergic-like reactions, complications following contrast medium extravasation, and fluid shifts. There is noteworthy variation in the osmolality of the various nonionic iodinated contrast agents approved for use in the United States with equivalent iodine concentrations (see Appendix A). Contrast media osmolality is of particular importance in neonates and small children. These patients are thought to be especially susceptible to fluid shifts and have a lower tolerance for intravascular (IV) osmotic loads when compared to adults. IV administration of a hyperosmolality contrast medium may theoretically result in migration of fluid from extravascular soft tissues into blood vessels, consequently expanding blood volume. If the fluid shift is large, cardiac failure and pulmonary edema can result. In children with significant pre-existing cardiac dysfunction, consideration should be given to the use of an iso-osmolality intravascular contrast agent. Contrast Media Viscosity Viscosity, a measure of fluid resistance to stress, is another important physical property of
Manual on Contrast Media – Version 7, 2010
Contrast Media in Children / 1
slower injection rate (compared to that used in older children and adults) may be useful to prolong IV enhancement. Second, small gauge...