Continuous renal replacement therapy without anticoagulation in critically ill patients at high risk of bleeding: A systematic review and meta-analysis

Optimizing Continuous Renal Replacement Therapy with Regional Citrate Anticoagulation: Insights from the ORCA Trial-A Retrospective Study on 10 Years of Practice

(1) Background: Citrate is preferred in continuous renal replacement therapy (CRRT) for critically ill patients because it prolongs filter life and reduces bleeding risks compared to unfractionated heparin (UFH). However, regional citrate anticoagulation (RCA) can lead to acid-base disturbances, citrate accumulation, and overload. This study compares the safety and efficacy of citrate-based CRRT with UFH and no anticoagulation (NA) in acute kidney injury (AKI) patients. (2) Methods: A retrospective analysis was conducted on adult patients (≥18 years) who underwent CRRT from July 2010 to June 2021 in an intensive care unit. (3) Results: Among 829 AKI patients on CRRT: 552 received RCA, 232 UFH, and 45 NA. The RCA group had a longer filter lifespan compared to UFH and NA (56 h [IQR, 24-110] vs. 36.0 h [IQR, 17-63.5] vs. 22 h [IQR, 12-48]; all Padj < 0.001). Bleeding complications were fewer in the RCA group than in the UFH group (median 3 units [IQR, 2-7 units] vs. median 5 units [IQR, 2-12 units]; Padj < 0.001) and fewer in the NA group than in the UFH group (median 3 units [IQR, 1-5 units] vs. 5 units [IQR, 2-12 units]; Padj = 0.03). Metabolic alkalosis was more common in the RCA group (32.5%) compared to the UFH (16.2%) and NA (13.5%) groups, while metabolic acidosis persisted more in the UFH group and NA group (29.1% and 34.6%) by the end of therapy vs. the citrate group (16.8%). ICU mortality was lower in the RCA group (52.7%) compared to the UFH group (63.4%; Padj = 0.02) and NA group (77.8%; Padj = 0.003). (4) Conclusions: Citrate anticoagulation outperforms heparin-based and no anticoagulation in filter patency, potentially leading to better outcomes through improved therapy effectiveness and reduced transfusion needs. However, careful monitoring is crucial to limit potential complications attributable to its use.

Comparison of diluted vs concentrated regional citrate anticoagulation in continuous renal replacement therapy: A quasi-experimental study

BACKGROUND

The incidence of coagulation of continuous renal replacement therapy circuits remains high. To the best of our knowledge, no scholar has published a protocol to avoid management errors when different types of citrates coexist in the same Intensive Care Unit.

AIM

To assess the safety and efficacy of the unification of two protocols with different concentrations of citrate solution.

STUDY DESING

A prospective, quasi-experimental study was carried out in the intensive care unit of a tertiary referral hospital (in Barcelona, Spain), over 3 years. Consecutive adult patients requiring continuous renal replacement therapy with citrate were included. The sample was divided into two groups, a control group (concentrated citrate) and an intervention group (diluted citrate). The decision to initiate anticoagulation with diluted (18 mmol/L) or concentrated (136 mmol/L) citrate was made based on the machine available and the decision of the doctor responsible for the patient. It was not possible to randomize the sample. Both protocols were matched with a starting citrate dose of 3.5 mmol/L, and a dialysis solution was used. Post-filter replacement was not used, and the citrate solution was the only fluid administered pre-filter.

RESULTS

The analysis included 59 circuits in the concentrated citrate group and 40 circuits in the diluted citrate group. An increased need for electrolyte replacement was observed in the diluted group (p < .001). The concentrated citrate group had a longer filter life (p < .05), and there was a slight trend toward alkalosis.

CONCLUSION

The diluted citrate group had a higher incidence of electrolyte replacement. The concentrated citrate group had longer circuit lifespan and a trend toward metabolic alkalosis, although this was not statistically significant. If these conclusions are considered, the protocol can be unified.

RELEVANCE TO CLINICAL PRACTICE

The present work aims to provide information on the differences in the use of regional anticoagulation with diluted or concentrated citrate. The objective is to pay special attention to aspects that can lead to complications. The unified protocol proposed in this paper could be extrapolated to any machine on the market that uses either of these two types of citrate concentration.

Coagulation Risk Predicting in Anticoagulant-Free Continuous Renal Replacement Therapy

INTRODUCTION

Continuous renal replacement therapy (CRRT) is a prolonged continuous extracorporeal blood purification therapy to replace impaired renal function. Typically, CRRT therapy requires routine anticoagulation, but for patients at risk of bleeding and with contraindications to sodium citrate, anticoagulant-free dialysis therapy is necessary. However, this approach increases the risk of CRRT circuit coagulation, leading to treatment interruption and increased resource consumption. In this study, we utilized artificial intelligence machine learning methods to predict the risk of CRRT circuit coagulation based on pre-CRRT treatment metrics.

METHODS

We retrospectively analyzed 212 patients who underwent anticoagulant-free CRRT from October 2022 to October 2023. Patients were categorized into high-risk and low-risk groups based on CRRT circuit coagulation within 24 h. We employed eight machine learning methods to predict the risk of circuit coagulation. The performance of the model was evaluated using the area under the curve (AUC) of the receiver operating characteristic. 5-fold cross-validation was used to validate the machine learning models. Feature importance and SHAP plots were used to interpret the model's performance and key drivers.

RESULTS

We identified 88 patients (41.51%) at high risk of circuit coagulation within 24 h of CRRT. Our machine learning models showed excellent predictive performance, with ensemble learning achieving an AUC of 0.863 (95% CI: 0.860-0.868), outperforming individual algorithms. Random forest was the best single-algorithm model, with an AUC of 0.819 (95% CI: 0.814-0.823). The top three features identified as most important by the SHAP summary plot and feature importance graph are platelet, filtration fraction (FF), and triglycerides.

CONCLUSION

We created a model using machine learning to predict the risk of circuit coagulation during anticoagulant-free CRRT therapy. Our model performs well (AUC 0.863) and identifies key factors like platelets, FF, and triglycerides. This facilitates the development of personalized treatment strategies by clinicians aimed at reducing circuit coagulation risk, thereby enhancing patient outcomes and reducing healthcare expenses.

Dose of nafamostat mesylate during continuous kidney replacement therapy in critically ill patients: a two-centre observational study

BACKGROUND

Nafamostat mesylate is an anticoagulant used for critically ill patients during continuous kidney replacement therapy (CKRT), characterised by its short half-life. However, its optimal dosage remains unclear. This study aimed to explore the optimal dosage of nafamostat mesylate during CKRT.

METHODS

We conducted a two-centre observational study. We screened all critically ill adult patients who required CKRT in the intensive care unit (ICU) from September 2013 to August 2021; we included patients aged ≥ 18 years who received nafamostat mesylate during CKRT. The primary outcome was filter life, defined as the time from CKRT initiation to the end of the first filter use due to filter clotting. The secondary outcomes included safety and other clinical outcomes. The survival analysis of filter patency by the nafamostat mesylate dosage adjusted for bleeding risk and haemofiltration was performed using a Cox proportional hazards model.

RESULTS

We included 269 patients. The mean dose of nafamostat mesylate was 15.8 mg/hr (Standard deviation (SD), 8.8; range, 5.0 to 30.0), and the median filter life was 18.3 h (Interquartile range (IQR), 9.28 to 36.7). The filter survival analysis showed no significant association between the filter life and nafamostat mesylate dosage (hazard ratio 1.12; 95 CI 0.74-1.69, p = 0.60) after adjustment for bleeding risk and addition of haemofiltration to haemodialysis.

CONCLUSIONS

We observed no dose-response relationship between the dose of nafamostat mesylate (range: 5 to 30 mg/h) and the filter life during CKRT in critically ill patients. The optimal dose to prevent filter clotting safely needs further study in randomised controlled trials.

TRIAL REGISTRATION

Not applicable.

Anti-Xa level monitoring of low-molecular-weight heparin during intermittent venovenous hemofiltration

Low-molecular-weight heparin (LMWH) is an anticoagulant used to prevent clotting during blood purification treatments. This study aimed to evaluate the clinical use of the anti-factor Xa level (anti-Xa) for monitoring LMWH anticoagulant levels during intermittent venovenous hemofiltration (IVVHF). This prospective observational study enrolled patients who required IVVHF for renal failure in Beijing Hospital between May 2019 and February 2021. The LMWH anticoagulation was assessed by the coagulation grade of the filter and line. One hundred and ten participants were included. There were 90 patients with a filter and line coagulation grade of ≤ 1 and 20 patients with grade > 1. The anti-Xa level of 0.2 IU/mL was a critical value. The multivariable logistic regression analysis showed that anti-Xa level > 0.2 IU/mL (odd ratio [OR] = 2.263; 95% CI: 1.290-4.871, P = 0.034) and cardiovascular disease (OR = 10.028; 95% CI: 1.204-83.488; P = 0.033) were independently associated with the coagulation grade of the filter and line. Anti-Xa level could monitor LMWH anticoagulation during IVVHF.

Anticoagulation options for continuous renal replacement therapy in critically ill patients: a systematic review and network meta-analysis of randomized controlled trials

BACKGROUND

Continuous renal replacement therapy (CRRT) is a widely used standard therapy for critically ill patients with acute kidney injury (AKI). Despite its effectiveness, treatment is often interrupted due to clot formation in the extracorporeal circuits. Anticoagulation is a crucial strategy for preventing extracorporeal circuit clotting during CRRT. While various anticoagulation options are available, there were still no studies synthetically comparing the efficacy and safety of these anticoagulation options.

METHODS

Electronic databases (PubMed, Embase, Web of Science, and the Cochrane database) were searched from inception to October 31, 2022. All randomized controlled trials (RCTs) that examined the following outcomes were included: filter lifespan, all-cause mortality, length of stay, duration of CRRT, recovery of kidney function, adverse events and costs.

RESULTS

Thirty-seven RCTs from 38 articles, comprising 2648 participants with 14 comparisons, were included in this network meta-analysis (NMA). Unfractionated heparin (UFH) and regional citrate anticoagulation (RCA) are the most frequently used anticoagulants. Compared to UFH, RCA was found to be more effective in prolonging filter lifespan (MD 12.0, 95% CI 3.8 to 20.2) and reducing the risk of bleeding. Regional-UFH plus Prostaglandin I2 (Regional-UFH + PGI2) appeared to outperform RCA (MD 37.0, 95% CI 12.0 to 62.0), LMWH (MD 41.3, 95% CI 15.6 to 67.0), and other evaluated anticoagulation options in prolonging filter lifespan. However, only a single included RCT with 46 participants had evaluated Regional-UFH + PGI2. No statistically significant difference was observed in terms of length of ICU stay, all-cause mortality, duration of CRRT, recovery of kidney function, and adverse events among most evaluated anticoagulation options.

CONCLUSIONS

Compared to UFH, RCA is the preferred anticoagulant for critically ill patients requiring CRRT. The SUCRA analysis and forest plot of Regional-UFH + PGI2 are limited, as only a single study was included. Additional high-quality studies are necessary before any recommendation of Regional-UFH + PGI2. Further larger high-quality RCTs are desirable to strengthen the evidence on the best choice of anticoagulation options to reduce all-cause mortality and adverse events and promote the recovery of kidney function. Trial registration The protocol of this network meta-analysis was registered on PROSPERO ( CRD42022360263 ). Registered 26 September 2022.

Analysis of the extracorporeal anticoagulation effect of modified citrate infusion during continuous renal replacement therapy in critically ill patients

INTRODUCTION

To analyze the anticoagulation effect of different local infusion methods of citrate underwent continuous renal replacement therapy (CRRT) in critically ill patients.

METHODS

The study adopted a single-centre retrospective design. Critically ill patients were divided into conventional group and modified group based on the infusion methods of citrate.

RESULTS

The modified group had a longer mean treatment time (67.67 ± 18.69  hours vs. 52.11 ± 24.26 hours, p = 0.007), a lower transmembrane pressure (147.77 ± 66.85 cm H₂ O vs. 200.63 ± 118.66 cm H₂ O, p = 0.038), fewer citrate bag replacements (1.43 ± 0.50 times vs. 10.60 ± 3.19 times, p < 0.001), and more steady ionized calcium at the venous end (0.35 ± 0.06 mmol/L vs. 0.40 ± 0.05 mmol/L, p = 0.006) compared to the conventional group patients, with statistically significant differences. The incidences of citrate accumulation and tubing coagulation were marginally lower in the modified group.

CONCLUSION

The modified local citrate infusion method can prolong treatment time, while reducing both the nursing workload and the occurrence of citrate accumulation.

Regional citrate anticoagulation (RCA) in critically ill patients undergoing renal replacement therapy (RRT): expert opinion from the SIAARTI-SIN joint commission

Renal replacement therapies (RRT) are essential to support critically ill patients with severe acute kidney injury (AKI), providing control of solutes, fluid balance and acid-base status. To maintain the patency of the extracorporeal circuit, minimizing downtime periods and blood losses due to filter clotting, an effective anticoagulation strategy is required.Regional citrate anticoagulation (RCA) has been introduced in clinical practice for continuous RRT (CRRT) in the early 1990s and has had a progressively wider acceptance in parallel to the development of simplified systems and safe protocols. Main guidelines on AKI support the use of RCA as the first line anticoagulation strategy during CRRT in patients without contraindications to citrate and regardless of the patient's bleeding risk.Experts from the SIAARTI-SIN joint commission have prepared this position statement which discusses the use of RCA in different RRT modalities also in combination with other extracorporeal organ support systems. Furthermore, advise is provided on potential limitations to the use of RCA in high-risk patients with particular attention to the need for a rigorous monitoring in complex clinical settings. Finally, the main findings about the prospective of optimization of RRT solutions aimed at preventing electrolyte derangements during RCA are discussed in detail.

Unfractionated heparin versus nafamostat mesylate for anticoagulation during continuous kidney replacement therapy: an observational study

BACKGROUND

Unfractionated heparin sodium and nafamostat mesylate have long been used as anticoagulants in continuous kidney replacement therapy (CKRT) where citrate is unavailable. This study aimed to determine whether heparin or nafamostat mesylate used during CKRT was associated with a longer filter life.

METHODS

In this single-centre observational study, we included adult patients who required CKRT and used heparin or nafamostat mesylate for their first CKRT in the intensive care unit from September 1, 2013, to December 31, 2020. The primary outcome was filter life (from the start to the end of using the first filter). We used propensity score matching to adjust for the imbalance in patients' characteristics and laboratory data at the start of CKRT and compared the outcomes between the two groups. We also performed restricted mean survival time analysis to compare the filter survival times.

RESULTS

We included 286 patients, 157 patients on heparin and 129 patients on nafamostat mesylate. After propensity score matching, the mean filter life with heparin was 1.58 days (N = 91, Standard deviation [SD], 1.52) and with nafamostat mesylate was 1.06 days (N = 91, SD, 0.94, p = 0.006). Multivariable regression analysis adjusted for confounding factors supported that heparin was associated with a longer filter life compared with nafamostat mesylate (regression coefficient, days, 0.52 [95% CI, 0.15, 0.89]). The between group difference of the restricted mean filter survival time in the matched cohort was 0.29 (95% CI, 0.07-0.50, p = 0.008).

CONCLUSION

Compared to nafamostat mesylate, heparin was associated with one-third to one-half a day longer filter life.

TRIAL REGISTRATION

Not applicable.