Premature circuit clotting due to likely mechanical failure during continuous renal replacement therapy

Objective: Failure of extracorporeal circuit (EC) function during continuous renal replacement therapy (CRRT) appears most likely due to progressive circuit clotting or, in some cases, most likely due to mechanical problems that affect flow. We aimed to study the incidence of such likely mechanical circuit failure (MCF). Design and Setting: Retrospective observational study in an adult ICU of a tertiary hospital. Patients and Measurements: We studied 30 patients treated with CRRT via femoral vein vascular access. We obtained information on age, gender, diagnosis, mode of CRRT, circuit life, and blood chemistry. We defined MCF as 'likely' if there was a reduction of between 60 and 80% in circuit life compared to the previous or following circuit life and 'very likely' if such a reduction was between 81 and 100%. Results: We studied 166 circuits in 30 different patients. Of these 26 were electively disconnected leaving 140 circuits with unplanned cessation of function. Among these circuits, likely MCF affected 10 circuits (7.1%) and very likely MCF affected 9 circuits (6.4%) for a total of 19 (13.6%) circuits. Conclusion: Mechanical circuit failure appears to affect approximately 1 in 8 circuits. Prospective studies are needed to understand why MCF occurs.