Introduction. Thrombolytic agents are frequently used as an aid to restore catheter patency despite limited evidence supporting their use. We therefore conducted a systematic review to evaluate the efficacy of tPA (alteplase) and reteplase in restoring catheter patency.
Methods. We searched MEDLINE (1999 to May Week 3 2007) and the Cochrane Controlled Clinical Trials Register (Second Quarter 2007) and performed a manual search for further studies. Studies published before 1999 were excluded since they have been previously reviewed; furthermore, most such studies used urokinase, which is no longer used to restore catheter patency in North America. Studies were included if they described the efficacy of alteplase or reteplase in restoring patency of central venous catheters (either for hemodialysis or infusional treatment) and where more than 5 thrombotic episodes were reported. This latter exclusion criteria was used to reduce the likelihood of bias likely to be found in very small case series. Two independent researchers abstracted total thrombolytic dose administered, dwell times, catheter patency rates and adverse event (including bleeding rates). For purposes of comparison, dwell times were stratified as ≤ 30 minutes and 30 to 120 minutes.
Results. 25 articles were identified in the initial search, of which 17 met one or more exclusion criteria. Of the remaining 8 studies, 7 evaluated central venous catheters used for intravenous infusions and 1 study evaluated occluded hemodialysis catheters. Except for 1 randomized trial comparing thrombolytic agents to placebo in non-hemodialysis patients, all studies described uncontrolled cohorts or case series. The mean study size was 214 patients (range 6–995). At doses of 0.5–2.5 mg of alteplase, the range of catheter patency rates at dwell times of ≤ 30 minutes and 30 to 120 minutes were 52–54% (1301 total uses) and 69–91% (1466 total uses) respectively. In comparison when used with a ≤ 30 minute dwell time, reteplase was reported to restore catheter patency in 67–73% cases (154 total uses). In all reports bleeding complications attributed to thrombolytic therapy were uncommon.
Conclusion. Our review suggests that the installation of alteplase or reteplase will restore catheter patency in more than 50% of cases when used with a dwell time of at least 30 minutes. Longer dwell times appear to increase patency rates. Reteplase may be more effective than alteplase, although this observation should be validated in an adequately powered clinical trial. Overall, although modern thrombolytic agents appear to provide catheter patency in the majority of patients, the evidence supporting their use is of low quality and is not based on the results of randomized trials.