The effectiveness of hemodialysis depends, in part, on the delivery of the prescribed rate of blood flow and the amount of blood recirculation. Studies evaluating the magnitude of recirculation in double-lumen catheters at blood flow rates > or = 300 mL/min have not been performed. We therefore examined the effects of prescribed blood flow rate and placement site on measure blood flow, recirculation and effective clearance using double-lumen catheters in 17 patients. Double-lumen catheters were placed in the internal jugular (12.5 cm), subclavian (20 cm), and femoral veins (15 cm and 24 cm). Recirculation studies were performed in triplicate with a two-needle method at blood flow rates of 250, 300, 350, and 400 mL/min. Blood flow rate was measured with an ultrasonic flow meter placed on the venous line. The arterial line pressure was continuously monitored. Mean arterial line pressure was -105 +/- mm Hg at 250 mL/min and -231 +/- mm Hg at 400 mL/min prescribed blood flow rates in the internal jugular, subclavian, and 15-cm femoral vein catheters. Patients with 24-cm femoral catheters had a mean arterial line pressure of -196 +/- mm Hg at 250 mL/min and -327 +/- mm Hg at 400 mL/min. In spite of the change in arterial line pressure, measured blood flow rate increased appropriately at all set blood flows and with all catheter sites studied.(ABSTRACT TRUNCATED AT 250 WORDS)