Outpatient High-Dose Urokinase Infusion Improves Dialysis Catheter Longevity: A Prospective Observational Study

Abstract

C atheter thrombosis is a major limiting factor affecting catheter survival in hemodialysis (HD). A previous retrospective study highlighted the utility of outpatient intradialytic high-dose urokinase (HDU) infusion in the treatment of HD catheter thrombosis. The present study was designed to prospectively evaluate the effectiveness of 250 000 IU urokinase given as a 3-hour infusion during HD. The infusion would follow detection of a drop in blood flow thought to be secondary to thrombosis [a "thrombotic event" (TE)] after exclusion of nonthrombotic causes of drop in blood flow [a "nonthrombotic event" (NTE)], such as systemic hypotension or suboptimal position of the catheter on x ray. An "event" was defined as a drop in pump blood flow by greater than or equal to 20% of the prescribed blood flow. Twenty patients (mean age 57.7 years; 13 males) with documented or potentially long-term catheters were recruited (total catheters used, 30) from an outpatient HD unit. A variety of catheter types were used. Catheter position was confirmed on x ray. Hemodialysis sessions were monitored for 6 months or until catheter removal (whichever was earlier). Thrombotic and NTEs (mostly related to drop in blood flow) were noted. The use of intradialytic HDU infusions was monitored. Improvement was defined as reestablishment of blood flow to within 10% of prescription. There were 24 TEs in 11 patients and 15 NTEs in 7 patients. Twenty-one of 22 (95%) TEs responded to HDU, with complete restoration of blood flow; in 1/22 HDU-treated instances there was a partial response. For 2/24 TEs the patients underwent catheter stripping with good results. Twelve of 15 NTEs occurred in the first 2 weeks of catheter placement versus 6/24 TEs (p = 0.001, chi-square). Catheter survival was longer than 24 weeks in 12/30 catheters. Nine catheters were lost to NTEs. No catheter was lost secondary to a TE. It is therefore concluded that intradialytic outpatient HDU is useful for the treatment of HD catheter thrombosis. It may obviate/reduce the need for catheter stripping or replacement. Randomized controlled trials with this approach are needed. A higher proportion of NTEs tended to occur earlier after catheter placement compared to TEs.