Risk Factors Associated with Hemodialysis Central Venous Catheter Malfunction; A Retrospective Analysis of a Randomized Controlled Trial

Abstract

BackgroundWe previously reported a reduction in central venous catheter (CVC) malfunction when using once-weekly recombinant tissue-plasminogen activator (rt-PA) as a locking solution, compared with thrice-weekly heparin.ObjectivesTo identify risk factors for CVC malfunction to inform a targeted strategy for rt-PA use.DesignRetrospective analysis.SettingCanadian hemodialysis (HD) units.PatientsAdults with newly placed tunnelled upper venous system CVCs randomized to a locking solution of rt-PA(1 mg/mL) mid-week and heparin (5000 u/ml) on the other HD sessions, or thrice-weekly heparin (5000 u/ml).MeasurementsCVC malfunction (the primary outcome) was defined as: peak blood flow less than 200 mL/min for thirty minutes during a HD session; mean blood flow less than 250 mL/min for two consecutive HD sessions; inability to initiate HD.MethodsCox regression was used to determine the association between patient demographics, HD session CVC-related variables and the outcome of CVC malfunction.ResultsPatient age (62.4 vs 65.4 yr), proportion female sex (35.6 vs 48.4%), and proportion with first catheter ever (60.7 vs 61.3%) were similar between patients with and without CVC malfunction. After multivariate analysis, risk factors for CVC malfunction were mean blood processed < 65 L when compared with ≥ 85 L in the prior 6 HD sessions (HR 4.36; 95% CI, 1.59 to 11.95), and mean blood flow < 300 mL/min, or 300 – 324 mL/min in the prior 6 HD sessions (HR 7.65; 95% CI, 2.78 to 21.01, and HR 5.52; 95% CI, 2.00 to 15.23, respectively) when compared to ≥ 350 mL/min.LimitationsThis pre-specified post-hoc analysis used a definition of CVC malfunction that included blood flow, which may result in an overestimate of the effect size. Generalizability of results to HD units where trisodium citrate locking solution is used may also be limited.ConclusionsHD session characteristics including mean blood processed and mean blood flow were associated with CVC malfunction, while patient characteristics were not. Whether targeting these patients at greater risk of CVC malfunction with rt-PA as a locking solution improves CVC longevity remains to be determined.