Substitution of Citrate with Tissue Plasminogen Activator (rt-PA) for Catheter Lock Does Not Improve Patency of Tunneled Hemodialysis Catheters in a Randomized Trial

Abstract Background: The study aim was to establish if substitution of citrate with rt-PA for catheter lock once weekly can reduce the incidence of catheter-related blood stream infections (CR-BSI) or improve patency of tunneled hemodialysis catheters.Methods: All incident patients undergoing insertion of a tunneled hemodialysis catheter were screened and included except those suffering infection or using oral anticoagulation. Study participants were randomized into two arms according to the solution applied as catheter lock: receiving either trisodium citrate (Citra-LockTM 4%) only or rt-PA (Actilyse® 1mg/ml) on the middle session each week with citrate used on the first and third sessions. The incidence of CR-BSI (confirmed by positive blood culture), catheter non-function (complete obstruction), and malfunction (blood flow <250ml/min) was recorded. Statistical significance was tested with ANOVA, post hoc analysis was performed by means of multiple linear regression.Results: Totally, 18 patients were included and followed during 655 hemodialysis sessions. No episode of CR-BSI was detected while 6 catheter non-functions (0.9% sessions) and 101 malfunctions (15.4% sessions) were recorded. The incidence of both events was equal between the study arms: 4 non-functions and 55 malfunctions in the rt-PA arm and 2 non-functions and 46 malfunctions in the citrate arm (p=0.47 and p=0.24, respectively). Additionally, the mean blood flow achieved did not differ significantly between the arms: 326±1,8 and 326±1,9 ml/min (p=0.95) in rt-PA and citrate arms, respectively. Post hoc analysis identified time elapsed since previous session (β=0.12, p=0.005) and malfunction on previous session (β=0.25, p<0.001) as significant factors affecting the occurrence of malfunction. By contrast, the study arm, rt-PA application on previous session, and catheter vintage did not enter the model.Conclusion: Substitution of citrate with rt-PA for catheter lock does not reduce the incidence of catheter malfunction neither does it affect the blood flow achieved during hemodialysis. Catheter patency is related rather to the time interval between sessions and to previous malfunction (thus probably reflecting undefined individual factors). The incidence of CR-BSI within pre-selected hemodialysis population is sporadic (less than 1 per 4.3 patient years in our sample).Trial registration: The study was registered on the ACTRN 12612000152820