Relationship between viscosity and determined injection pressure in angiography catheters for common roentgen contrast media.

The viscosity of 8 commercially available contrast media (CM) at 2 or 3 concentrations were measured as a function of concentration and temperature, using a rotational viscosmeter. Further on, by use of an automated injector, injection pressures were measured for 3 of the CM at various concentrations, temperatures, catheter lengths, catheter diameters and flow rates. The experiments were performed as fractional factorial designs. The correlation between the injection pressure and the viscosity was found to be log-linear, and an empiric equation was established for this relationship. The relative reduction of viscosity - and therby injection pressure - with increasing injection temperature, was largest for the most concentrated CM. Iodixanol and iotrolan, the 2 nonionic dimers investigated, demonstrated an increased viscosity compared to the nonionic monomers at equal concentrations. However, all CM investigated could be used with an acceptable injection pressure either by relatively small changes in catheter conditions or by adjustment of injection temperature closer to body temperature.