For the critically ill patient with complex and prolonged needs, multiple drug infusions and, when indicated, peripheral hyperalimentation require simultaneous administration through a simple peripheral catheter site with a multilumen catheter. We studied a double-lumen peripheral venous catheter. Ten domestic swine, 10 to 20 kg, were divided into two groups of five each. Total parenteral nutrition was administered through the distal port and phenytoin was administered as a bolus and as an infusion in each group. Samples were taken from two sites during the bolus and at 1, 5, and 15 min during phenytoin infusion. Electromagnetic flowmeter measurements were obtained for validation of flow. In all instances, our study showed that either the particle size was too small or the concentration of particles was less than 3 X 10(3)/microL: too small to be recovered in the study samples.