Adequacy of haemodialysis with cuffed central-vein catheters

Abstract

Cuffed central-venous haemodialysis catheters are emerging as an alternative permanent haemodialysis vascular access. There is limited data regarding the adequacy of dialysis with prolonged used of these catheters. We conducted a prospective study comparing three commonly used cuffed central-venous haemodialysis catheters: (1) PermCath, Quinton Instrument Co, Seattle; (2) Tesio, Med Comp, Inc, Harleysville PA; (3) VasCath Soft Cell, Bard Instrument Company, Toronto, and compared them with control patients dialysing with arteriovenous access (AV) access. We randomly assigned 64 patients who needed prolonged temporary vascular access to placement of one of three catheters. The control group comprised 222 patients dialysing simultaneously in the same units with AV access.

Methods: All patients were dialysed with identical machines and kidneys. Maximal effort were made with every catheter to optimize achievable blood flow. Catheters with mechanical problems were treated first with urokinase and then fibrin sheath catheter stripping. The mean blood flow was determined by averaging mean blood flows from 30 consecutive treatments. Reliability of catheter was defined as percentage of treatments that were performed at a median blood flow of 350 ml/min or above during these 30 treatments. Kt/V was measured monthly and calculated using the single-pool Daugirdas formula. Haemodialysis prescription were adjusted for Kt/V above 1.2. Recirculation was measured using two-needle low-blood-flow technique.

Results: The mean blood flows were (PermCath 383.6 ml/min, Tesio 396.3 ml/min, VasCath 320.4 ml/min). PermCath and Tesio had comparable mean blood flows and were significantly higher than VasCath (P<0.005). Reliability of catheters were (PermCath 86.9%, Tesio 81.6%, VasCath 42.3%). Tesio and PermCath were equally reliable and both were more reliable than VasCath (P<0.005). Had the target for reliability been 300 ml/min all three catheters would have been equally reliable. Negative arterial pressure in excess of 300 mmHg prevented faster blood flows in 98% of instances. None of the catheters performed as well as the control population with AV access (mean blood flow 437ml/min, reliability 96%, P<0.005). Recirculation rates were 3.7% for PermCath 3.9% for Tesio, and 4% for VasCath. All patients weighing less than 85 kg acheived a Kt/V of 1.2 with a 4-h treatment. For comparison purposes when Kt/V was normalized to a 70-kg patient the results were PermCath 1.42. Tesio 1.44, VasCath 1.19, AV access 1.64.

Summary: All three catheters are capable of providing adequate haemodialysis although large patients will need extended treatment times. The PermCath and Tesio provide blood flow and reliability superior to the VasCath. Blood flow is limited in all catheters by inflow, as evidenced by negative arterial pressure. All catheters had acceptable recirculation. AV access is superior in terms of blood flow and reliability to all tested catheters.