Measurement of the Concentration of Citrate in Human Biofluids in Patients Undergoing Continuous Renal Replacement Therapy Using Regional Citrate Anticoagulation: Application of a Two-Step Enzymatic Assay

Safety of Citrate Anticoagulation in CKRT: Monocentric Experience of a Dynamic Protocol of Calcium Monitoring

Regional Citrate Anticoagulation (RCA) is considered the first-line anticoagulation for Continuous Kidney Replacement Therapy (CKRT). The RCA requires strict protocols and trained staff to avoid unsafe use and ensure its benefit. We have analyzed all our CKRT prescriptions from December 2020 to April 2022 anonymously, collecting data on CKRT, lab tests, clinical conditions, and complications of RCA. In addition, in order to better detect citrate accumulation, we have performed an RCA protocol by reducing the CaTot/Ca2+ ratio cut-off from 2.50 to 2.40 and increasing the number of calcium checks according to its trend. Among the 374 patients in CKRT, 104 received RCA prescriptions, of which 11 (10.6%) were discontinued: 4 for the suspicion of citrate accumulation, 1 for the development of metabolic alkalosis, 1 for the shift to a different CKRT procedure due to the need for a higher bicarbonate dose, 4 for the elevation of hepatocytolysis indexes, and 1 due to a preemptive discontinuation following massive post-surgery bleeding. None of the patients have had citrate toxicity as indicated by a CaTot/Ca2+ greater than 2.50, and our protocol has allowed the early identification of patients who might develop clinical citrate toxicity.

Management of regional citrate anticoagulation for continuous renal replacement therapy: guideline recommendations from Chinese emergency medical doctor consensus

Continuous renal replacement therapy (CRRT) is widely used for treating critically-ill patients in the emergency department in China. Anticoagulant therapy is needed to prevent clotting in the extracorporeal circulation during CRRT. Regional citrate anticoagulation (RCA) has been shown to potentially be safer and more effective and is now recommended as the preferred anticoagulant method for CRRT. However, there is still a lack of unified standards for RCA management in the world, and there are many problems in using this method in clinical practice. The Emergency Medical Doctor Branch of the Chinese Medical Doctor Association (CMDA) organized a panel of domestic emergency medicine experts and international experts of CRRT to discuss RCA-related issues, including the advantages and disadvantages of RCA in CRRT anticoagulation, the principle of RCA, parameter settings for RCA, monitoring of RCA (mainly metabolic acid-base disorders), and special issues during RCA. Based on the latest available research evidence as well as the paneled experts' clinical experience, considering the generalizability, suitability, and potential resource utilization, while also balancing clinical advantages and disadvantages, a total of 16 guideline recommendations were formed from the experts' consensus.

A Comparison of the Commonly Used Surrogate Markers for Citrate Accumulation and Toxicity during Continuous Renal Replacement Therapy with Regional Citrate Anticoagulation

INTRODUCTION

Continuous renal replacement therapy using regional citrate anticoagulation is commonly used as a modality of organ support in the critically ill population. Currently, citrate accumulation or toxicity is assessed using surrogate markers, notably the uncorrected total-to-ionized calcium ration. The accuracy and utility of this method have been questioned.

OBJECTIVES/AIMS

The aim of this study was to compare the surrogate markers used for assessing citrate accumulation or toxicity using the measurement of plasma citrate as the gold standard.

METHODS

Blood was sampled from 20 patients before, during, and after episodes of filtration with citrate concentration measured using spectrophotometry. Demographic and other clinical and biochemical data were also collected. According to protocol, a 15 mmol/L solution of trisodium citrate was used as the prefilter anticoagulant. Results were analyzed using STATA (v16.0) and presented as mean (SD), median (IQR), or simple proportion. Univariate linear regression using citrate concentration as the dependent variable was performed with all surrogate markers.

RESULTS

Twenty patients (17 males) were enrolled in the study with a mean (SD) age of 62.7 (9.9) years. The uncorrected calcium ratio had the best fit to the citrate data with an R2 value of 0.39. The albumin-corrected calcium ratio, pH, anion gap (AG), albumin-corrected AG, standard base excess, and strong ion gap all had R2 values less than 0.05.

CONCLUSION(S)

In the absence of direct measurement of citrate concentration, uncorrected total-to-ionized calcium ratio is superior to other surrogate markers, though not ideal, in assessing citrate accumulation or toxicity.