Blood flow and recirculation rates in tunneled hemodialysis catheters.

Long-term catheters are widely used in some dialysis units. Because of higher dialysis dose targets, high flow catheters have been made available. We measured blood flow (Qb in ml/min) and recirculation rate (R%) in two types of tunneled dialysis catheters using ultrasound-dilution technology (Transonic). Thirty-seven catheters were evaluated (27 Opti-Flow, 10 High-Flow), as inserted in jugular or subclavian veins. Real Qb and R were measured at increasing pump blood flows (250, 300, 350, 400, and 450 ml/min) in absence of ultrafiltration. For all, real Qb was similar to pump Qb (261 vs. 250, 304 vs. 300, 349 vs. 350, 389 vs. 400, and 431 vs. 450 ml/min, respectively). Catheters with reversed lines were all recirculating (R between 18% and 24%). Sixteen nonreversed catheters had no R at all Qb, whereas four nonreversed catheters had minimal R (between 7% and 11%); R did not increase significantly with the rise in pump Qb. The two types of tunneled catheters deliver high Qb without high R if ports are not reversed. The relative decrease in treatment efficiency should be accounted for in dialysis prescription if such tunneled catheters are used as long-term access, especially if lines have to be reversed.