In Vitro Investigations of Citrate Clearance with Different Dialysis Filters

An individualized regional citrate anticoagulation protocol for hemodialysis: a real-world retrospective study

OBJECTIVE

To evaluate the safety and effectiveness of an individualized regional citrate anticoagulation (RCA) protocol for hemodialysis.

METHODS

In this single-center, retrospective study, blood coagulation in the extracorporeal circulation, adverse reactions, in vivo ionized calcium (iCa2+) concentrations, and the infusion dose of citrate during RCA in hemodialysis were observed in 98 patients from February 2021 to March 2022.

RESULTS

A total of 98 patients underwent RCA during hemodialysis 362 times, and blood coagulation occurred in the extracorporeal circulation 29 times. Among the 29 cases of coagulation, most of the patients exhibited hypercoagulability, and among approximately 80% of the treatments, the deviation between the actual infusion rate of citrate in the extracorporeal circulation and the theoretical value was ± 10%. After hemodialysis, pH values and bicarbonate ion (HCO3-) levels were clearly improved, and online conductivity monitoring (OCM) values and blood coagulation scores in the extracorporeal circulation were identical to those measured in similar studies.

CONCLUSION

An individualized RCA protocol for hemodialysis is safe, effective, simple, and inexpensive and can meet the needs of individualized treatment; therefore, its application is worthy of promotion.

Regional Citrate Anticoagulation: A Tale of More Than Two Stories

Calcium is a key clotting factor, and several inorganic molecules that bind to calcium have been found to reduce the clotting propensity of blood. Citrate, a calcium chelator, is used as inhibitor of the coagulation cascade in blood transfusion. Also, it is used as an anaticoagulant during dialysis to maintain patency of the extracorporeal circuit, known as regional citrate anticoagulation (RCA). The amount of citrate should be chosen such that ionized calcium concentrations in the extracorporeal circuit are reduced enough to minimize propagation of the coagulation cascade. The dialytic removal of the calcium-citrate complexes combined with reduced ionized calcium concentrations makes necessary calcium supplementation of the blood returning to the patient. This can be achieved in different ways. In classical RCA, citrate and calcium are infused in the afferent and efferent tubing, respectively, whereas the dialysate does not contain calcium. This setup has been shown to be highly efficacious with a very low clotting propensity. Strict monitoring of blood electrolytes is required. Alternatively, the use of a high-calcium dialysate leads to calcium loading, obviating the need for a separate calcium infusion pump. The main advantages are simplified delivery of RCA and less fluctuation of systemic calcium concentrations. Currently, citric acid is sometimes added to the acid concentrate as a replacement for acetic acid. Differences and similarities between RCA and citrate-containing dialysate are discussed. RCA is an excellent alternative to heparin for patients at high risk of bleeding.

A simplified protocol for individualized regional citrate anticoagulation for hemodialysis: A single-center, randomized clinical study

INTRODUCTION

The lack of individualized treatment protocols and complicated procedures are important factors limiting the use of regional citrate anticoagulation (RCA) technology in hemodialysis. This study aims to validate the safety and efficacy of a simplified individualized RCA protocol for hemodialysis.

MATERIALS AND METHODS

From June 2019 to August 2019, 45 patients with active bleeding or bleeding tendency undergoing maintenance hemodialysis in the Nephrology Department of the First Affiliated Hospital of Nanchang University were randomly divided into a modified conventional RCA protocol group with a low-flux dialyzer, a simplified individualized RCA protocol group with a high-flux dialyzer, and a simplified individualized RCA protocol group with a low-flux dialyzer.

RESULTS

A total of 45 patients were included in this study. The mean age of the patients was 57.38 ± 19.05 years, and 78% were men. Forty-three patients completed 4 hours of hemodialysis, and the median total clotting scores in the 3 groups were 11, 12, and 12. Compared with the modified conventional RCA protocol group with a low-flux dialyzer, the 2 simplified individualized RCA protocol groups had better clotting scores for the dialyzer, arterial bubble trap, and single-pool urea clearance index (spKt/VBUN) and lower costs. Moreover, these parameters did not differ between the 2 simplified individualized RCA protocol groups. No electrolyte or acid-base imbalances or citrate poisoning was observed in any of the 3 groups. Adverse events did not differ significantly among the 3 groups.

CONCLUSIONS

The simplified individualized RCA protocol is safe, effective, and easy to implement. Therefore, this protocol can be promoted for clinical practice.

TRIAL REGISTRATION

This study was registered in the Chinese Clinical Study Registry under registration number ChiCTR1900023801.

Chemical and microbiological stability, anticoagulant efficacy and toxicity of 35 and 90 mM trisodium citrate solutions stored in plastic syringes

Background

Trisodium citrate is an interesting alternative to heparin for the prevention of circuit clotting during extracorporeal procedures, but some protocols require non-commercially available citrate concentrations. Little published information is available about the stability of diluted citrate solutions.

Objectives

To evaluate the long-term stability, efficacy and toxicity of 35 mM and 90 mM trisodium citrate solutions prepared by diluting a commercially available sterile solution, stored in plastic syringes and used as an anticoagulant during citrate bag changes in the coupled plasma filtration adsorption (CPFA) technique in the COMPACT-2 clinical trial.

Methods

The chemical stability of trisodium citrate solutions was evaluated by high-performance liquid chromatography after 7, 14, 21 and 28 days of storage. Sterility tests were performed both immediately after preparation and after 28 days of storage.

Results

After 28 days of storage, the concentration of trisodium citrate had not changed in comparison with day 1, and both solutions passed the sterility test. A preliminary test indicated that a 35 mM solution is insufficient to ensure an effective anticoagulant action on an extracorporeal circuit, but the 90 mM solution was successfully used for 7 CPFA treatments in 2 patients, without clinical signs of toxicity.

Conclusions

Both the 35 mM and 90 mM solutions are chemically and microbiologically stable for 28 days when stored at room temperature in 50 mL syringes protected by light. The 90 mM solution is an effective and safe regional anticoagulant in the CPFA protocol.

Trial registration number

NCT01639664.

A prediction and simulation model for target-oriented regional citrate-calcium anticoagulation in extracorporeal blood purification

AIMS

Regional citrate-calcium anticoagulation is becoming more and more attractive for extracorporeal treatments in the clinical routine.

METHODS

A prediction and simulation tool for the safe application of RCA during extracorporeal treatments was introduced. The model predicts the course of the ionized calcium level in the patient and the current anticoagulation status in the extracorporeal circuit based on the actual settings of the dialysis machine.

RESULTS

The simulation tool delivers areas in which the blood and dialysate flow can be adjusted to reach the desired target values for RCA and predicts the time course of several parameters during treatment.

Heparin albumin priming in a clinical setting for hemodialysis patients at risk for bleeding

INTRODUCTION

Intermittent hemodialysis (IHD) is sometimes necessary in patients with a bleeding risk, i.e., before/after surgery or brain hemorrhage. In such case IHD has to be modified to limit the conventional anticoagulation used to avoid clotting of the extracorporeal circuit (ECC). We evaluated if priming using a heparin and albumin (HA) mixture could minimize the exposure to heparin.

METHODS

Retrospective data from 1995 to 2013 were collected from 1408 acute dialysis treatment protocols that included 321 patients. Comparisons were made between IHD patients that had increased risk for bleeding and were treated by standard anticoagulation (Group-S), and patients at increased risk of bleeding (Group-HA). The ECC in Group-HA was primed with a solution of unfractioned heparin (UFH) (5000 Units/L) and albumin (1 g/L) in saline that was discarded after priming. There were 16 different dialyzers in the material.

FINDINGS

Comparing Group-S (n = 883) with Group-HA (n = 221), the mean age was 61.6 vs. 62.2 years (P = 0.8), dialysis time was 197 vs. 190 minutes (P = 0.002), and total dose of intravenous anticoagulant/IHD was at median 5000 Units vs. 1200 Units (P = 0.001). Twenty-four percent of patients were treated without any additional heparin. Clotting resulting in interrupted dialysis was similar in both groups (0.8% for Group-S vs. 1.0% for Group-HA, P = 0.8). No secondary bleeding was reported in either group.

DISCUSSION

HA priming minimized the risk of clotting and enabled acute IHD in vulnerable patients without increased bleeding, thus allowing completion of IHD to the same extent as for standard HD.

Dieter Falkenhagen (1942–2015): A Multifaceted Scientist

Dieter Falkenhagen was born in 1942 in Dresden, Germany and died in 2015. He specialized in internal medicine and nephrology. Focusing on artificial organ research, he investigated various aspects of the efficacy and safety of hemodialysis and adsorption technologies, including biocompatibility issues related to blood versus surface interactions and the adverse effects of endotoxin contamination. He studied various mathematical models to analyze efficacy and safety, and animal models to help clarify uncertainty issues. Through his studies, adsorbents were developed, resulting in Prometheus, an artificial liver support device. Anticoagulation models, including citrate perfusion, were improved and made safer by his work. He also stepped into bioreactor research to increase efficacy of liver support devices.

A target-oriented algorithm for citrate-calcium anticoagulation in clinical practice

BACKGROUND/AIMS

Because of a high monitoring demand and an ensuing need for automation of regional citrate anticoagulation (RCA), a new semi-automated target-oriented algorithm was developed. The aim of this study was the evaluation of its functionality and safety.

METHODS

Fourteen haemodialysis patients were treated 5 times consecutively with RCA. Samples were drawn pre- and post-infusion once per hour. Electrolytes, blood cell counts, acid-base and coagulation parameters were analyzed.

RESULTS

Mean ionized calcium (Ca(2+)) values pre-filter were 0.23 and 0.33 mmol/l in the 0.2 and 0.3 mmol/l target groups, respectively. Extraction ratios for citrate and total calcium through the dialysis filter were constant during the entire treatment (83 and 68%, respectively). Citrate accumulation was avoided.

CONCLUSION

The new algorithm enables safe and accurate RCA. By regulating Ca(2+) pre-filter using the target-oriented algorithm, the degree of anticoagulation may be easily controlled.