Heparin-free regional anticoagulation of haemodialysis filters with calcium-free dialysate: is citrate mandatory?

Background. There is an unmet need to develop safe and successful heparin-free regional anticoagulation modalities in haemodialysed patients at risk of bleeding. Whether the addition of citrate as a prefilter injection or in the dialysate itself is required to reach anticoagulation objectives when calcium-free dialysate is used as regional anticoagulation remains unclear. Methods. In this monocentric retrospective study, we report our experience of 908 dialysis sessions performed with a calcium-free citrate-containing dialysate and calcium reinjection according to the ionic dialysance, without additional heparin. Results. Premature termination for filter clotting occurred in 20 sessions (2.2%) and duration of session was >4.5h in 135 (15%; maximum duration 6h). In addition, we could investigate the citrate, calcium and acid-basis status during haemodialysis sessions performed with (citrate group, n=20 sessions) or without (citrate-free group, n=19 sessions) citrate in the dialysate. In 20 sessions performed in patients with underlying liver disorders and using calcium-free citrate-containing dialysate, patients' ionized calcium (iCa) and serum citrate levels were stable and remained within the normal range, respectively. Post-filter iCa was below 0.4mmol/L in 19/20 sessions and citrate was 0.304mmol/L (range: 0.011; 0.548). In 19 sessions that used calcium and citrate-free dialysate, post-filter iCa was 0.41mmol/L (0.34; 0.5) and all sessions extended to 4h or beyond. Conclusions. Regional anticoagulation of haemodialysis with a calcium-free dialysate and calcium reinjection according to the ionic dialysance is safe. Adding citrate to the dialysate is not mandatory to prevent dialysis circuit clotting in most patients.