[Determination of dobutamine levels in human plasma--methodological and clinical aspects].

We developed a simple method for the routine determination of dobutamine in human plasma. With a relatively small amount of equipment--such as HPLC pump, RP 18-column, sample valve, fluorescence detector and an integrator--dobutamine levels could be determined quickly after a simple extraction procedure on Bond-Elut-CN-columns. In the case of critically ill patients suffering from different kinds of shock we found a wide variation of plasma levels in arterial blood samples. Even with an exact application of dobutamine in relatively low doses of about 2.5 micrograms/kg BW/min to 5 micrograms/kg BW/min, levels reached from 26.8 to 181 micrograms/ml. In our opinion, one reason for these variations might be a differing volume of distribution caused by varying intravascular volumes in critically ill patients. A further possibility might be a different degree of sulfoconjugation of dobutamine. Therefore, the occasional occurrence of tachycardia under dobutamine therapy could be caused by relatively high plasma levels of free dobutamine.