Efficacy, Safety, and Calcium Balance of an Accelerated Citrate Anticoagulated Membrane-Based Plasma Exchange Algorithm

Abstract

Introduction: To assess the safety, efficacy, and calcium flux of an accelerated algorithm for regional citrate anticoagulation in membrane-based plasma exchange. Methods: This was an observational study in patients receiving citrate anticoagulated, membrane-based plasma exchange at the Canberra Hospital between July 2017 and May 2020. Data were collected prospectively using an electronic medical record and compared to data from our previous published algorithm. Results: There were 134 plasma exchange sessions performed during the observational period. Circuit clotting occurred in 4 sessions, and 1 session was affected by symptomatic hypocalcaemia. A systemic ionized calcium <0.96 mmol/L was seen in 19.4% of sessions, which was a similar frequency to that seen in our previous algorithm. A systemic ionized Ca <0.81 mmol/L occurred in 4 sessions (all asymptomatic). This hypocalcaemia occurred towards the end of the sessions, after switching from albumin to fresh frozen plasma replacement fluid. Median treatment time was 135 min, compared to 219 min in our previously published algorithm. Mean net Ca gain/session was 7.7 ± 2.3 mmol. Conclusion: An accelerated algorithm for regional citrate anticoagulation achieves substantial time saving while maintaining efficacy and safety. The 4 episodes of systemic ionized calcium <0.81 mmol/L may have been due to recirculation of infused citrate but, probably more likely, are due to the additional citrate load imposed by use of fresh frozen plasma in these sessions. Future algorithms need to better account for the citrate load present in fresh frozen plasma.