An evaluation of different dilution modes on circuit lifespan during continuous veno-venous hemodiafiltration without anticoagulation.

Background: Circuit clotting remains a major problem during continuous kidney replacement therapy (CKRT), particularly in patients with contraindications to anticoagulant use. We hypothesized that the different options of alternative replacement fluid infusion sites might affect circuit lifespan. However, research-based evidence supporting an optimal replacement fluid infusion strategy is limited. Therefore, we aimed to evaluate the effect of three dilution modes (pre-dilution, post-dilution, and pre- to post-dilution) on circuit lifespan during continuous veno-venous hemodiafiltration (CVVHDF).

Methods: This prospective cohort study was conducted between December 2019 and December 2020. Patients requiring CKRT were enrolled to receive pre-dilution, post-dilution, or pre- to post-dilution fluid infusion with CVVHDF. The primary endpoint was circuit lifespan, and the secondary outcomes included the clinical parameters of patients, such as changes in serum creatinine (Scr) and blood urea nitrogen (BUN) levels, 28-day all-cause mortality, and length of stay. For all patients included in this study, only the first circuit used was recorded.

Results: Among the 132 patients enrolled in this study, 40 were in the pre-dilution mode, 42 were in the post-dilution mode, and 50 were in the pre- to post-dilution mode. The mean circuit lifespan was significantly longer in the pre- to post-dilution group (45.72 h, 95% CI, 39.75-51.69 h) than in the pre-dilution group (31.58 h, 95% CI, 26.33-36.82 h) and the post-dilution group (35.20 h, 95% CI, 29.62-40.78 h). There was no significant difference between the pre- and post-dilution group circuit lifespan (p > 0.05). Kaplan-Meier survival analysis revealed a significant difference between the three dilution modes (p = 0.001). No significant differences were observed in terms of changes in the Scr and BUN levels, admission day, and 28-day all-cause mortality among the three dilution groups (p > 0.05).

Conclusion: The pre- to post-dilution mode significantly prolonged circuit lifespan but did not reduce Scr and BUN levels, compared with the pre-dilution and post-dilution modes during CVVHDF when no anticoagulants were used.