The antithrombic agent might disrupt catheter-lumen biofilms, which could predispose to infection.
Intra-dialytic instillation of tissue plasminogen activator (tPA) may be associated with increased catheter-related bacteremia (CRB).
“Perhaps by using tPA we are disrupting the biofilm [inside catheter lumens], which could possibly lead to an increased risk of infection,” said lead investigator Carol Manierski, PharmD, clinical pharmacy specialist in the department of nephrology at the Henry Ford Health System in Detroit. “We use this agent but we are not sure if we are doing more harm than good. We have demonstrated that we might be harming patients but this is a retrospective study so we need to better look at what may be happening here.”
The use of tPA is growing in popularity as a catheter-locking agent to prevent catheter occlusion even though long-term safety and efficacy data are lacking.

Dr. Manierski and her colleagues conducted a case-control study over a 12-month period (January 2005 through December 2005) of all tunneled dialysis catheters at Henry Ford. Overall, the researchers evaluated 673 tunneled catheter months in 144 patients. The catheters were present in patients for a mean 5.3 months; they were jugular in 82.6% of cases and femoral in 17.4%.

Catheters were locked with tPA in 45% of patients, heparin in 53%, or gentamicin/vancomycin/heparin in 2%. A total of 57 episodes of CRB occurred, with a unit rate of 8.5 episodes per 100 catheter months or 2.92/1,000 catheter days.

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A total of 471 catheter months were locked 100% with tPA or heparin. The CRB rate was 13.1% for the tPA group compared to 6.0% in the heparin group. Femoral catheters had a higher rate of CRB compared with jugular catheters (18.2% vs. 7.5%).  Catheter age was not associated with increased rates of CRB. “Using tPA in femoral catheters exponentially increases the risk,” Dr. Manierski told Renal & Urology News.

“Perhaps if we can reconstitute tPA in bacteriostatic water instead of sterile water, which is current practice, we could mitigate the increased risk for CRB that we are seeing here. However, the package insert recommends reconstituting it in sterile water so it would be an off-label use.”

It is important to use tPA for certain groups of patients, so new ways to use the medication more safely are needed, she said.