Regional anticoagulation with citrate: expanding its indications

Regional citrate anticoagulation for replacement therapy in patients with liver failure: A systematic review and meta-analysis

Background

Citrate refers to an anticoagulant agent commonly used in extracorporeal organ support. Its application is limited in patients with liver failure (LF) due to the increased risk of citrate accumulation induced by liver metabolic dysfunction. This systematic review aims to assess the efficacy and safety of regional citrate anticoagulation in extracorporeal circulation for patients with liver failure.

Methods

PubMed, Web of Science, Embase, and Cochrane Library were searched. Studies regarding extracorporeal organ support therapy for LF were included to assess the efficacy and safety of regional citrate anticoagulation. Methodological quality of included studies were assessed using the Methodological Index for Non-randomized Studies (MINORS). Meta-analysis was performed using R software (version 4.2.0).

Results

There were 19 eligible studies included, involving 1026 participants. Random-effect model showed an in-hospital mortality of 42.2% [95%CI (27.2, 57.9)] in LF patients receiving extracorporeal organ support. The during-treatment incidence of filter coagulation, citrate accumulation, and bleeding were 4.4% [95%CI (1.6-8.3)], 6.7% [95%CI (1.5-14.4)], and 5.0% [95%CI (1.9-9.3)], respectively. The total bilirubin(TBIL), alanine transaminase (ALT), aspartate transaminase(AST), serum creatinine(SCr), blood urea nitrogen(BUN), and lactate(LA) decreased, compared with those before the treatment, and the total calcium/ionized calcium ratio, platelet(PLT), activated partial thromboplastin time(APTT), serum potential of hydrogen(pH), buffer base(BB), and base excess(BE) increased.

Conclusion

Regional citrate anticoagulation might be effective and safe in LF extracorporeal organ support. Closely monitoring and timely adjusting during the process could reduce the risk for complications. More prospective clinical trials of considerable quality are needed to further support our findings.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42022337767.

Effectiveness and Safety Assessment of Citrate Anticoagulation During Albumin Dialysis in Comparison to Other Methods of Anticoagulation

Liver failure is a serious and often deadly disease often requiring MARS (Molecular Adsorbent Recirculating System) therapy. Choosing the safe and effective method of anticoagulation during artificial liver support systems seems to be very difficult and extremely important. The aim of this study was to assess effectiveness and safety of regional anticoagulation with citrate in liver failure patients during MARS. We used a single center observational study. We analyzed 158 MARS sessions performed in 65 patients: 105 (66.5%) sessions in 41 patients with heparin anticoagulation, 40 (25.3%) sessions in 19 patients with citrate, and 13 (8%) sessions in only five patients without anticoagulation, that were excluded from part of the analysis. To determine the effectiveness of regional anticoagulation with citrate, probability of filter survival and changes in laboratory parameters were analyzed according to the applied method of anticoagulation. The safety of citrate was determined by Ca/Ca²⁺ ratio, acid-base balance, bleeding complications, and the need for blood product transfusions. The probability of filter survival in the citrate group was 94% and in the heparin group 82% (P = 0.204). There was no relationship between the method of anticoagulation and effectiveness of MARS therapy in lowering the levels of the analyzed parameters. Only one patient had a Ca/Ca²⁺ ratio higher than he safety margin. There were no statistically significant changes in pH and lactate level irrespective of anticoagulation; bicarbonate dropped significantly only in the heparin group (P = 0.03). The frequency of bleeding complications and the need for transfusions did not differ significantly between groups. Regional anticoagulation with citrate can be an effective and safe method of anticoagulation during MARS therapy, but requires attentive monitoring and further studies in liver failure patients.

Sustained low-efficiency dialysis with regional citrate anticoagulation in medical intensive care unit patients with liver failure: A prospective study

PURPOSE

Patients with liver failure requiring dialysis are at increased risk for citrate accumulation during sustained low-efficiency dialysis (SLED). The aim of this study was to evaluate the feasibilty of citrate SLED in critical ill patients with liver failure and investigate predictive parameters regarding citrate accumulation.

MATERIALS AND METHODS

This is a prospective study in 24 medical intensive care unit patients with liver failure and a total of 43 SLED runs (maximum of 3 runs per patient) using citrate anticoagulation. Liver function was characterized before SLED using not only laboratory parameters but also determination of the plasma disappearance rate of indocyanine green. In addition, blood gas parameters as well total calcium and citrate in serum were measured at baseline and defined time points during SLED.

RESULTS

Accumulation of citrate could be observed in all SLED runs, which were nearly normalized until the end of SLED and 24 hours after SLED, respectively. However, the critical threshold of total calcium/ionized calcium on ratio of greater than 2.5 was exceeded in only 1 patient. Equalization of initial metabolic acidosis was possible without major disturbances of acid base and electrolyte status. Liver function parameters showed poor predicitve capabilities regarding citrate accumulation.

CONCLUSIONS

Despite substantial accumulation of citrate in serum, SLED is save and feasible in patients with liver failure using a citrate anticoagulation. Careful monitoring of electrolytes and acid base status is mandatory to ensure patient safety.

Continuous venovenous hemodialysis with regional citrate anticoagulation in patients with liver failure: a prospective observational study

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 (Ca_tot/Ca_ion) ratio ≥2.5, and to describe the feasibility of citrate CVVHD in liver failure patients.

Methods

We conducted a prospective observational study in medical ICU 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 two CVVHD runs per patient). Liver function was characterized before CVVHD using laboratory parameters, calculation of Child-Pugh and Model of End-stage Liver Disease scores, and determination of the plasma disappearance rate of indocyanine green. In addition to blood gas analysis, we measured total calcium and citrate in serum at baseline and after definitive time points for each CVVHD run.

Results

Accumulation of citrate in serum correlated with an increase in the Ca_tot/Ca_ion ratio. Although the critical upper threshold of Ca_tot/Ca_ion ratio ≥2.5 was exceeded 10 times in seven 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 Ca_tot/Ca_ion ratio ≥2.5. In contrast, serum lactate ≥3.4 mmol/l and prothrombin time ≤26% predicted an increase in the Ca_tot/Ca_ion ratio ≥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 severely impaired liver function. Citrate accumulation in serum is reflected by an increase in the Ca_tot/Ca_ion ratio. To identify patients at risk for citrate accumulation in terms of a Ca_tot/Ca_ion ratio ≥2.5, baseline serum lactate (threshold ≥3.4 mmol/l) and prothrombin time (threshold ≤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.

[Continuous haemodialysis with citrate anticoagulation in patients with liver failure: three cases]

Regional citrate anticoagulation for continuous renal replacement therapy provides an efficient alternative to heparin as it reduces the likelihood of haemorrhage in critically ill patients with bleeding risk or coagulopathy and increases the haemofilter survival time. Liver failure is a classic contraindication of regional citrate anticoagulation since it carries the risk of citrate accumulation and its metabolic complications, although it could be attractive for this population of patients with high bleeding risk. We report three cases of continuous haemodialysis with regional citrate anticoagulation performed in patients with severe acute liver failure, without accumulation in two cases and with a suspected beginning of accumulation in the third case. For these patients, close monitoring of the total-to-ionized calcium ratio, pH and anion gap is particularly essential to control the safety of citrate infusion. Increasing effluent flow rate eliminates more calcium-bound citrate and therefore limits citrate accumulation and its consequences.

A prospective randomized open-label crossover trial of regional citrate anticoagulation vs. anticoagulation free liver dialysis by the Molecular Adsorbents Recirculating System

Introduction

The Molecular Adsorbent Recycling System (MARS) is used to treat patients with liver failure. Observational data suggest that citrate anticoagulation during MARS is feasible. Comparative studies on the optimal anticoagulation regimen during MARS are lacking. The aim of the current study was to evaluate two heparin-free anticoagulation regimens.

Methods

We performed a prospective randomized open-label crossover study of regional citrate anticoagulation against no anticoagulation. Ten patients (age 55 ± 11 years) with liver failure undergoing MARS treatment were included. The primary endpoint was completion of MARS sessions. Secondary endpoints included treatment efficacy and safety. Longevity of MARS treatment was plotted as a Kaplan-Meier estimate. Fisher's exact test was used for contingency table analysis.

Results

Of a total of 27 6-hour sessions, four sessions had to be terminated prematurely, three due to occlusive clotting of the extracorporeal circuit and one due to uncontrollable bleeding from the vascular access site. All four events occurred in the group without anticoagulation. Between group comparison demonstrated citrate anticoagulation to significantly increase the likelihood of completed MARS treatment (Fisher's exact test, P 0.04). This translates into higher bilirubin reduction ratios when citrate was applied (reduction ratio 0.25 vs. 0.15, P 0.02). Systemic ionized calcium concentrations were significantly reduced during citrate anticoagulation (P < 0.001) but remained within a safe range. We observed no major adverse events.

Conclusions

Regional citrate anticoagulation in patients with liver failure is feasible. Citrate anticoagulation provides superior patency of the extracorporeal circuit. Avoidance of anticoagulation during MARS results in significant loss of treatment efficacy, due to treatment downtime. Additional studies are required to identify the optimal anticoagulation regimen for extracorporeal circulation in patients with liver failure.

Regional citrate versus heparin anticoagulation for continuous renal replacement therapy: a meta-analysis of randomized controlled trials

BACKGROUND

Anticoagulation of the extracorporeal circuit is required in continuous renal replacement therapy (CRRT). Heparin is the classic choice for anticoagulation, although it may increase the risk of bleeding. Regional citrate anticoagulation reduces the risk of bleeding, but may cause hypocalcemia and metabolic disturbances.

STUDY DESIGN

Systematic review and meta-analysis of randomized controlled trials (RCTs).

SETTING & POPULATION

Patients admitted to the intensive care unit with acute kidney injury that required CRRT.

SELECTION CRITERIA FOR STUDIES

RCTs regardless of publication status or language.

INTERVENTION

Regional citrate versus heparin anticoagulation in CRRT.

OUTCOMES

The primary outcomes were circuit survival time, the occurrence of major bleeding defined as a site of gross bleeding with a decrease in blood pressure or requiring transfusion of 2 or more units of red blood cells, metabolic alkalosis, hypocalcemia, and thrombocytopenia. The secondary outcome was cost.

RESULTS

6 RCTs with 488 patients were identified. Citrate anticoagulation was associated with a significant decrease in bleeding (RR, 0.34; 95% CI, 0.17-0.65). Circuit survival time, the incidence of metabolic alkalosis, and thrombocytopenia showed no significant difference between groups. Hypocalcemia was more common in patients receiving citrate, although no clinical adverse event was reported in the included studies.

LIMITATIONS

Significant heterogeneity in the primary outcome.

CONCLUSION

The efficacy of citrate and heparin anticoagulation for CRRT was similar. However, citrate anticoagulation decreased the risk of bleeding with no significant increase in the incidence of metabolic alkalosis. We recommend citrate as an anticoagulation agent in patients who require CRRT but are at high risk of bleeding.