Caroline Schultheiss, Bernd Saugel, Veit Phillip, Philipp Thies, Ulrich Mayr, Sebastian Noe, Bernhard Haller, Henrik Einwachter, Roland M Schmid, Wolfgang Huber Critical Care 2012, 16:R162 (22 August 2012)
Introduction: Liver failure patients might be at risk for citrate accumulation during continuous venovenous hemodialysis (CVVHD) with regional citrate anticoagulation. The aim of this study was to investigate the predictive capability of baseline liver function parameters regarding citrate accumulation expressed as an increase in the calcium total/calcium ionized (Catot/Caion) ratio of [greater than or equal to]2.5 and to describe the feasibility of citrate CVVHD in liver failure patients.
Methods: We conducted a prospective observational study in medical intensive care unit patients treated in a German university hospital. We performed 43 CVVHD runs using citrate for regional anticoagulation in 28 critically ill patients with decompensated liver cirrhosis or acute liver failure (maximum of 2 CVVHD runs per patient). Liver function was characterized before CVVHD using laboratory parameters, calculation of Child-Pugh- and MELD-score, and determination of the plasma disappearance rate of indocyanine green (ICG-PDR). In addition to blood gas analysis, we measured total calcium and citrate in serum at baseline and after definitive time points of each CVVHD run.
Results: Accumulation of citrate in serum correlated with an increase in the Catot/Caion ratio. Although the critical upper threshold of Catot/Caion ratio of [greater than or equal to]2.5 was exceeded 10 times in 7 different CVVHD runs, equalization of initial metabolic acidosis was possible without major disturbances of acid-base and electrolyte status. Standard laboratory liver function parameters showed poor predictive capabilities regarding citrate accumulation in terms of an elevated Catot/Caion ratio of [greater than or equal to]2.5. In contrast, serum lactate [greater than or equal to]3.4 mmol/L and prothrombin time [less than or equal to]26% predicted an increase in the Catot/Caion ratio of [greater than or equal to]2.5 with high sensitivity (86% for both lactate and prothrombin time) and specificity (86% for lactate, 92% for prothrombin time).
Conclusions: Despite substantial accumulation of citrate in serum, CVVHD with regional citrate anticoagulation seems feasible in patients with severly impaired liver function. Citrate accumulation in serum is reflected by an increase in the Catot/Caion ratio. In order to identify patients who are at risk for citrate accumulation in terms of a Catot/Caion ratio of [greater than or equal to]2.5, baseline serum lactate (threshold [greater than or equal to]3.4 mmol/L) and prothrombin time (threshold [less than or equal to]26%) may be useful for risk prediction in daily clinical practice. Careful monitoring of electrolytes and acid-base-status is mandatory to ensure patient safety.
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