Blood and ultrafiltrate dosage of citrate as a useful and routine tool during continuous venovenous haemodiafiltration in septic shock patients

Background. Citrate anticoagulation is gaining popularity in renal replacement therapies(RRT) for critically ill patients. In order to study whether citrate accumulates in septic shockpatients, we determined citrate in plasma and dialysate during continuous venovenous haemodiafiltration (CVVHDF). Methods. An automated routine determination of citrate was set up using a commercial kit (citrate lyase method). Twelve patients with septic shockon CVVHDF and citrate anticoagulation were studied ex vivo for citrate levels in systemic and circuit blood and in the ultrafiltrate (at 0, 0.5, 1, 3, 6, 9, 12, 24, 48 and 72 h). Results. In vitro blood studies showed a near unit correlation between the plasma measured and predicted citrate concentrations for an exclusive extracellular distribution of citrate. Median systemic arterial citratemias were 0.09 (0.06–0.12) mmol/L (Time 0) and 0.23 (0.18–0.31) mmol/ L during treatment; median sieving coefficientfor citrate was 0.95 (0.88–1.02) and did not change with different volumes of CVVHDF effluent (from 1350 to 5100 mL/h). Net citrate and calcium removal by filter significantly correlated with effluent volume (r ¼ 0.85 and 0.78, respectively). Median citrate load entering in the patients’ bloodstream was 13.60 (9.1–19.6, n ¼ 68) mmol/h. Although cost analysis of the citrate testdemonstrated a minimally increased daily cost (from 2.96 to 3.51V), saving costs could be potentially relevant with more extended use of citrate anticoagulation. Conclusions. In septic shockpatients with liver dysfunction citratemia is useful in guiding clinical application of RRT, where the citrate losses in the ultrafiltrate can be efficiently modulated by increasing the effluent volume.