Safety and efficacy of regional citrate anticoagulation for continuous renal replacement therapy in liver failure patients: a systematic review and meta-analysis

Regional citrate anticoagulation versus LMWH anticoagulation for CRRT in liver failure patients without increased bleeding risk

BACKGROUND

The optimal anticoagulation regimen for continuous renal replacement therapy (CRRT) in liver failure (LF) patients without increased bleeding risk remains controversial. Therefore, we conducted a monocentric retrospective study to evaluate the efficacy and safety of the regional citrate anticoagulation (RCA) versus low molecular weight heparin (LMWH) anticoagulation for CRRT in LF without increased bleeding risk.

METHOD

According to the anticoagulation strategy for CRRT, patients were divided into the RCA and LMWH-anticoagulation groups. The evaluated endpoints were patient survival, filter lifespan, bleeding, citrate accumulation, and totCa/ionCa ratio.

RESULT

Totally 167 and 164 filters were used in the RCA and LMWH group, respectively. The median filter lifespan was significantly longer in the RCA group (34 h (IQR = 24-54) versus 24 h (IQR = 18-45.5) [95%CI, 24.5-33]; p < 0.001). The 4-week mortality rate was significantly higher in the LMWH-anticoagulation group (71 (57.72%) vs 53 (40.46%); p = 0.006). After adjusted the important parameters in the multivariate COX regression model, the mortality risk was significantly reduced in the RCA group (HR = 0.668 [95%CI, 0.468-0.955]; p = 0.027). In the LMWH group, 30 bleeding episodes (24,19%) were observed, whereas only 7 (5.34%) occurred in the RCA group (p < 0.001). Two patients (1.5%) in the RCA group occurred citrate accumulation.

CONCLUSIONS

In LF patients without increased bleeding risk who underwent CRRT, RCA significantly extended the filter lifespan and improved patient survival rate. There was no significant difference in the rate of adverse events between the two groups.

Deciphering simplified regional anticoagulation with citrate in intermittent hemodialysis: a clinical and computational study

Regional citrate anticoagulation use in intermittent hemodialysis is limited by the increased risk of metabolic complications due to faster solute exchanges than with continuous renal replacement therapies. Several simplifications have been proposed. The objective of this study was to validate a mathematical model of hemodialysis anticoagulated with citrate that was then used to evaluate different prescription scenarios on anticoagulant effectiveness (free calcium concentration in dialysis filter) and calcium balance. A study was conducted in hemodialyzed patients with a citrate infusion into the arterial line and a 1.25 mmol/L calcium dialysate. Calcium and citrate concentrations were measured upstream and downstream of the citrate infusion site and in the venous line. The values measured in the venous lines were compared with those predicted by the model using Bland and Altman diagrams. The model was then used with 22 patients to make simulations. The model can predict the concentration of free calcium, bound to citrate or albumin, accurately. Irrespective of the prescription scenario a decrease in free calcium below 0.4 mmol/L was obtained only in a fraction of the dialysis filter. A zero or slightly negative calcium balance was observed, and should be taken into account in case of prolonged use.

How to safeguard the continuous renal replacement therapy circuit: a narrative review

The high prevalence of acute kidney injury (AKI) in ICU patients emphasizes the need to understand factors influencing continuous renal replacement therapy (CRRT) circuit lifespan for optimal outcomes. This review examines key pharmacological interventions-citrate (especially in regional citrate anticoagulation), unfractionated heparin (UFH), low molecular weight heparin (LMWH), and nafamostat mesylate (NM)-and their effects on filter longevity. Citrate shows efficacy with lower bleeding risks, while UFH remains cost-effective, particularly in COVID-19 cases. LMWH is effective but associated with higher bleeding risks. NM is promising for high-bleeding risk scenarios. The review advocates for non-tunneled, non-cuffed temporary catheters, especially bedside-inserted ones, and discusses the advantages of surface-modified dual-lumen catheters. Material composition, such as polysulfone membranes, impacts filter lifespan. The choice of treatment modality, such as Continuous Veno-Venous Hemodialysis (CVVHD) or Continuous Veno-Venous Hemofiltration with Dialysis (CVVHDF), along with the management of effluent volume, blood flow rates, and downtime, are critical in prolonging filter longevity in CRRT. Patient-specific conditions, particularly the type of underlying disease, and the implementation of early mobilization strategies during CRRT are identified as influential factors that can extend the lifespan of CRRT filters. In conclusion, this review offers insights into factors influencing CRRT circuit longevity, supporting evidence-based practices and suggesting further multicenter studies to guide ICU clinical decisions.

Continuous renal replacement therapy and therapeutic plasma exchange in pediatric liver failure

Patients with acute liver failure (ALF) and acute on chronic liver failure (ACLF) have significant morbidity and mortality. They require extracorporeal blood purification modalities like continuous renal replacement therapy (CRRT) and therapeutic plasma exchange (TPE) as a bridge to recovery or liver transplantation. Limited data are available on the outcomes of patients treated with these therapies. This is a retrospective single-center study of 23 patients from 2015 to 2022 with ALF/ACLF who underwent CRRT and TPE. We aimed to describe the clinical characteristics and outcomes of these patients. Median (IQR) age was 0.93 years (0.57, 9.88), range 16 days to 20 years. Ten (43%) had ALF and 13 (57%) ACLF. Most (n = 19, 82%) started CRRT for hyperammonemia and/or hepatic encephalopathy and all received TPE for refractory coagulopathy. CRRT was started at a median of 2 days from ICU admission, and TPE started on the same day in most. The liver transplant was done in 17 (74%), and 2 recovered native liver function. Four patients, all with ACLF, died prior to ICU discharge without a liver transplant. The median peak ammonia pre-CRRT was 131 µmol/L for the whole cohort. The mean (SD) drop in ammonia after 48 h of CRRT was 95.45 (43.72) µmol/L in those who survived and 69.50 (21.70) µmol/L in those who did not (p 0.26). Those who survived had 0 median co-morbidities compared to 2.5 in non-survivors (aOR (95% CI) for mortality risk of 2.5 (1.1-5.7), p 0.028).  Conclusion: In this cohort of 23 pediatric patients with ALF or ACLF who received CRRT and TPE, 83% survived with a liver transplant or recovered with their native liver. Survival was worse in those who had ACLF and those with co-morbid conditions. What is Known: •  Pediatric acute liver failure is associated with high mortality. •  Patients may require extracorporeal liver assist therapies (like CRRT, TPE, MARS, SPAD) to bridge them over to a transplant or recovery of native liver function. What is New: • Standard volume plasma exhange has not been evaluated against high volume plasma exchange for ALF. • The role, dose, and duration of therapeutic plasma exchange in patients with acute on chronic liver failure is not well described.

Standard vs. carbone dioxide adapted kidney replacement therapy in hypercapnic ARDS patients: a randomized controlled pilot trial (BigBIC)

BACKGROUND

Current continuous kidney replacement therapy (CKRT) protocols ignore physiological renal compensation for hypercapnia. This study aimed to explore feasibility, safety, and clinical benefits of pCO2-adapted CKRT for hypercapnic acute respiratory distress syndrome (ARDS) patients with indication for CKRT.

METHODS

We enrolled mechanically ventilated hypercapnic ARDS patients (pCO2 > 7.33 kPa) receiving regional citrate anticoagulation (RCA) based CKRT in a prospective, randomized-controlled pilot-study across five intensive care units at the Charité-Universitätsmedizin Berlin, Germany. Patients were randomly assigned 1:1 to the control group with bicarbonate targeted to 24 mmol/l or pCO2-adapted-CKRT with target bicarbonate corresponding to physiological renal compensation. Study duration was six days. Primary outcome was bicarbonate after 72 h. Secondary endpoints included safety and clinical endpoints. Endpoints were assessed in all patients receiving treatment.

RESULTS

From September 2021 to May 2023 40 patients (80% male) were enrolled. 19 patients were randomized to the control group, 21 patients were randomized to pCO2-adapted-CKRT. Five patients were excluded before receiving treatment: three in the control group (consent withdrawal, lack of inclusion criteria fulfillment (n = 2)) and two in the intervention group (lack of inclusion criteria fulfillment, sudden unexpected death) and were therefore not included in the analysis. Median plasma bicarbonate 72 h after randomization was significantly higher in the intervention group (30.70 mmol/l (IQR 29.48; 31.93)) than in the control group (26.40 mmol/l (IQR 25.63; 26.88); p < 0.0001). More patients in the intervention group received lung protective ventilation defined as tidal volume < 8 ml/kg predicted body weight. Thirty-day mortality was 10/16 (63%) in the control group vs. 8/19 (42%) in the intervention group (p = 0.26).

CONCLUSION

Tailoring CKRT to physiological renal compensation of respiratory acidosis appears feasible and safe with the potential to improve patient care in hypercapnic ARDS.

TRIAL REGISTRATION

The trial was registered in the German Clinical Trials Register (DRKS00026177) on September 9, 2021 and is now closed.

APASL clinical practice guidelines on the management of acute kidney injury in acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is a syndrome that is characterized by the rapid development of organ failures predisposing these patients to a high risk of short-term early death. The main causes of organ failure in these patients are bacterial infections and systemic inflammation, both of which can be severe. For the majority of these patients, a prompt liver transplant is still the only effective course of treatment. Kidneys are one of the most frequent extrahepatic organs that are affected in patients with ACLF, since acute kidney injury (AKI) is reported in 22.8-34% of patients with ACLF. Approach and management of kidney injury could improve overall outcomes in these patients. Importantly, patients with ACLF more frequently have stage 3 AKI with a low rate of response to the current treatment modalities. The objective of the present position paper is to critically review and analyze the published data on AKI in ACLF, evolve a consensus, and provide recommendations for early diagnosis, pathophysiology, prevention, and management of AKI in patients with ACLF. In the absence of direct evidence, we propose expert opinions for guidance in managing AKI in this very challenging group of patients and focus on areas of future research. This consensus will be of major importance to all hepatologists, liver transplant surgeons, and intensivists across the globe.

Safety and Feasibility of Regional Citrate Anticoagulation for Continuous Renal Replacement Therapy With Calcium-Containing Solutions: A Randomized Controlled Trial

BACKGROUND

Calcium-free (Ca-free) solutions are theoretically the most ideal for regional citrate anticoagulation (RCA) in continuous renal replacement therapy (CRRT). However, the majority of medical centers in China had to make a compromise of using commercially available calcium-containing (Ca-containing) solutions instead of Ca-free ones due to their scarcity. This study was designed to probe into the potential of Ca-containing solution as a secure and efficient substitution for Ca-free solutions.

METHODS

In this prospective, randomized single-center trial, 99 patients scheduled for CRRT were randomly assigned in a 1:1:1 ratio to one of three treatment groups: continuous veno-venous hemodialysis Ca-free dialysate (CVVHD Ca-free) group, continuous veno-venous hemodiafiltration calcium-free dialysate (CVVHDF Ca-free) group, and continuous veno-venous hemodiafiltration Ca-containing dialysate (CVVHDF Ca-containing) group at cardiac intensive care unit (CICU). The primary endpoint was the incidence of metabolic complications. The secondary endpoints included premature termination of treatment, thrombus of filter, and bubble trap after the process.

RESULTS

The incidence of citrate accumulation (18.2% vs. 12.1% vs. 21.2%) and metabolic alkalosis (12.1% vs. 0% vs. 9.1%) did not significantly differ among three groups (p > 0.05 for both). The incidence of premature termination was comparable among the groups (18.2% vs. 9.1% vs. 9.1%, p = 0.582). The thrombus level of the filter and bubble trap was similar in the three groups (p > 0.05 for all).

CONCLUSIONS

In RCA-CRRT for CICU population, RCA-CVVHDF with Ca-containing solutions and traditional RCA with Ca-free solutions had a comparable safety and feasibility.

TRIAL REGISTRATION

ChiCTR2100048238 in the Chinese Clinical Trial Registry.

Anticoagulation in renal replacement therapies: Why heparin should be abandoned in critical ill patients?

Extracorporeal circuits used in renal replacement therapy (RRT) can develop thrombosis, leading to downtimes and reduced therapy efficiency. To prevent this, anticoagulation is used, but the optimal anticoagulant has not yet been identified. Heparin is the most widely used anticoagulant in RRT, but it has limitations, such as unpredictable pharmacokinetics, nonspecific binding to plasma proteins and cells, and the possibility of suboptimal anticoagulation or bleeding complications, specifically in critically ill patients with acute renal failure who are already at high risk of bleeding. Citrate anticoagulation is a better alternative, being considered a standard for continuous renal replacement therapy, since it is associated with a lower risk of bleeding complications and better efficacy, even in patients with acute renal failure or liver disease. The aim of this article is to provide an updated review of the different strategies of anticoagulation in renal replacement therapies that can be implemented in critical scenarios, focusing on the advantages and disadvantages of each one and the beneficial aspects of using citrate over heparin in critical ill patients.

Renal Replacement Therapy in Cirrhosis: A Contemporary Review

Acute kidney injury is a common complication of decompensated cirrhosis, frequently requires hospitalization, and carries a high short-term mortality. This population experiences several characteristic types of acute kidney injury: hypovolemic-mediated (prerenal), ischemic/nephrotoxic-mediated (acute-tubular necrosis), and hepatorenal syndrome. Prerenal acute kidney injury is treated with volume resuscitation. Acute-tubular necrosis is treated by optimizing perfusion pressure and discontinuing the offending agent. Hepatorenal syndrome, a unique physiology of decreased effective arterial circulation leading to renal vasoconstriction and ultimately acute kidney injury, is treated with plasma expansion with albumin and splanchnic vasoconstrictors such as terlipressin or norepinephrine. Common acute stressors such as bleeding, infection, and volume depletion often contribute to multifactorial acute kidney injury. Even with optimal medical management, many clinicians are faced with the challenge of initiating renal replacement therapy in these patients. This article reviews the epidemiology, indications, and complex considerations of renal replacement therapy for acute kidney injury in decompensated cirrhosis.

A single center retrospective study: Comparison between centrifugal separation plasma exchange with ACD-A and membrane separation plasma exchange with heparin on acute liver failure and acute on chronic liver failure

The purpose of this retrospective study is to compare the efficacy and safety of the centrifugal separation therapeutic plasma exchange (TPE) using citrate anticoagulant (cTPEc) with membrane separation TPE using heparin anticoagulant (mTPEh) in liver failure patients. The patients treated by cTPEc were defined as cTPEc group and those treated by mTPEh were defined as mTPEh group, respectively. Clinical characteristics were compared between the two groups. Survival analyses of two groups and subgroups classified by the model for end-stage liver disease (MELD) score were performed by Kaplan-Meier method and were compared by the log-rank test. In this study, there were 51 patients in cTPEc group and 18 patients in mTPEh group, respectively. The overall 28-day survival rate was 76% (39/51) in cTPEc group and 61% (11/18) in mTPEh group (P > .05). The 90-day survival rate was 69% (35/51) in cTPEc group and 50% (9/18) in mTPEh group (P > .05). MELD score = 30 was the best cut-off value to predict the prognosis of patients with liver failure treated with TPE, in mTPEh group as well as cTPEc group. The median of total calcium/ionized calcium ratio (2.84, range from 2.20 to 3.71) after cTPEc was significantly higher than the ratio (1.97, range from 1.73 to 3.19) before cTPEc (P < .001). However, there was no significant difference between the mean concentrations of total calcium before cTPEc and at 48 h after cTPEc. Our study concludes that there was no statistically significant difference in survival rate and complications between cTPEc and mTPEh groups. The liver failure patients tolerated cTPEc treatment via peripheral vascular access with the prognosis similar to mTPEh. The prognosis in patients with MELD score < 30 was better than in patients with MELD score ≥ 30 in both groups. In this study, the patients with acute liver failure (ALF) and acute on chronic liver failure (ACLF) treated with cTPEc tolerated the TPE frequency of every other day without significant clinical adverse event of hypocalcemia with similar outcomes to the mTPEh treatment. For liver failure patients treated with cTPEc, close clinical observation and monitoring ionized calcium are necessary to ensure the patients' safety.

Regional Citrate Anticoagulation versus No Anticoagulation for CKRT in Patients with Liver Failure with Increased Bleeding Risk

BACKGROUND

The opinions on the efficacy and safety of no anticoagulation versus regional citrate anticoagulation for continuous KRT (CKRT) were controversial in patients with severe liver failure with a higher bleeding risk. We performed a randomized controlled trial to assess no anticoagulation versus regional citrate anticoagulation for CKRT in these patients.

METHODS

Adult patients with liver failure with a higher bleeding risk who required CKRT were considered candidates. The included participants were randomized to receive regional citrate anticoagulation or no-anticoagulation CKRT. The primary end point was filter failure.

RESULTS

Of the included participants, 44 and 45 were randomized to receive regional citrate anticoagulation and no-anticoagulation CKRT, respectively. The no-anticoagulation group had a significantly higher filter failure rate (25 [56%] versus 12 [27%], P = 0.003), which was confirmed by cumulative incidence function analysis and sensitive analysis including only the first CKRT sessions. In the cumulative incidence function analysis, the cumulative filter failure rates at 24, 48, and 72 hours of the no-anticoagulation and regional citrate anticoagulation groups were 31%, 58%, and 76% and 11%, 23%, and 35%, respectively. Participants in the regional citrate anticoagulation group had significantly higher incidences of Ca 2+tot /Ca 2+ion >2.5 (7% versus 57%, P < 0.001), hypocalcemia (51% versus 82%, P = 0.002), and severe hypocalcemia (13% versus 77%, P < 0.001). However, most (73%) of the increased Ca 2+tot /Ca 2+ion ratios were normalized after the upregulation of the calcium substitution rate. In the regional citrate anticoagulation group, there was no significant additional increase in the systemic citrate concentration after 6 hours.

CONCLUSIONS

For patients with liver failure with a higher bleeding risk who required CKRT, regional citrate anticoagulation resulted in significantly longer filter lifespan than no anticoagulation. However, regional citrate anticoagulation in patients with liver failure was associated with a significantly higher risk of hypocalcemia, severe hypocalcemia, and Ca 2+tot /Ca 2+ion >2.5.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

RCA for CRRT in Liver Failure and High Risk Bleeding Patients, NCT03791190 .

Construction and validation of a prediction model for the risk of citrate accumulation in patients with hepatic insufficiency receiving continuous renal replacement therapy with citrate anticoagulation

BACKGROUND

To construct and validate a prediction model of the risk of citrate accumulation in patients with hepatic dysfunction receiving continuous renal replacement therapy with regional citrate anticoagulation (RCA-CRRT), which reduces the risk of citrate accumulation.

METHODS

All patients who received RCA-CRRT from 2021 to 2022 and were hospitalized in the First Affiliated Hospital of Zhejiang University were considered for study participation. Logistic regression analysis was used to identify the risk factors for citrate accumulation, based on which a nomogram model was constructed and validated in the validation group.

RESULTS

Six factors were finally identified, from which a nomogram was created to predict the risk of citrate accumulation. The area under the curve of the prediction model was 0.814 in the training group and 0.819 in the validation group, and the model showed acceptable agreement between the actual and predicted probabilities. Decision curve analysis also demonstrated that the model was clinically useful.

CONCLUSIONS

The model constructed from six factors reliably predicted the risk of citrate accumulation in patients with hepatic insufficiency who received RCA-CRRT.

Heparin anticoagulation versus regional citrate anticoagulation for membrane therapeutic plasma exchange in patients with increased bleeding risk

Background Heparin anticoagulation (HA) is commonly employed for membrane therapeutic plasma exchange (mTPE). However, for patients with increased bleeding risk, there were controversial opinions on the use of HA versus regional citrate anticoagulation (RCA) for mTPE. Our present study aimed to evaluate the efficacy and safety of HA vs. RCA for mTPE in patients with increased bleeding risk.Methods Patients with increased bleeding risk who underwent mTPE between 2014 and 2021 in our center were screened. Observations of anticoagulation efficacy and safety were used as the study endpoints.Results A total of 108 patients with 368 mTPE sessions were included. Of the included patients, 38 and 70 received HA and RCA mTPE, respectively. There was no significant difference in the clotting of extracorporeal circuits between the HA and RCA groups (4.1% vs. 4.4%, p = 0.605). More bleeding episodes were observed in the HA group compared to the RCA group (16.4% vs. 4.4% mTPE sessions, p < 0.001). The frequency of postoperative transfusion within 24 h (11% vs. 3.4%, p = 0.007) was significantly different in the HA and RCA group. Anticoagulation strategy (HA vs. RCA; OR 5.659, 95%CI 2.266-14.129; p < 0.001), and mean arterial pressure (prior treatment, OR 1.052, 95%CI 1.019-1.086; p = 0.002) were independent risk factors of bleeding episodes. At the end of mTPE treatment, the incidence of metabolic alkalosis (16.7% vs. 54.1%, p = 0.027) and hypocalcemia (41.7% vs. 89.2%, p = 0.001) was significantly different in the HA (n = 5, 12 sessions) and RCA (n = 22, 74 sessions) groups, respectively.Conclusion RCA is as effective as HA for mTPE. However, for patients with increased bleeding risk, RCA is associated with a lower risk of bleeding, compared with HA. With careful monitoring and timely adjustment, RCA most likely is a safe and effective anticoagulation option for mTPE in patients with increased bleeding risk.

Nanobody-functionalized conduit with built-in static mixer for specific elimination of cytokines in hemoperfusion

Removing excessively produced cytokines is of paramount significance in blood purification therapy for hypercytokinemia-associated diseases. In this study, we devised a conduit that is modified with nanobodies (Nb) and incorporates static mixers (Nb-SMC) to eliminate surplus cytokines from the bloodstream. The low-pressure-drop (LPD) static mixer, with each unit featuring two 90°-crossed blades, was strategically arranged in a tessellated pattern on the inner wall of the conduit to induce turbulent mixing effects during the flow of blood. This arrangement enhances mass transfer and molecular diffusion, thereby assisting in the identification and elimination of cytokines. By utilizing computational fluid dynamics (CFD) studies, the Nb-SMC was rationally designed and prepared, ensuring an optimal interval between two mixer units (H/G = 2.5). The resulting Nb-SMC exhibited a remarkable selective clearance of IL-17A, reaching up to 85 %. Additionally, the process of Nb immobilization could be adjusted to achieve the simultaneous removal of multiple cytokines from the bloodstream. Notably, our Nb-SMC displayed good blood compatibility without potential adverse effects on the composition of human blood. As the sole documented static mixer-integrated conduit capable of selectively eliminating cytokines at their physiological concentrations, it holds promise in the clinical potential for hypercytokinemia in high-risk patients. STATEMENT OF SIGNIFICANCE: High-efficient cytokines removal in critical care still remains a challenge. The conduit technique we proposed here is a brand-new strategy for cytokines removal in blood purification therapy. On the one hand, nanobody endows the conduit with specific recognition of cytokine, on the other hand, the build-in static mixer enhances the diffusion of antigenic cytokine to the ligand. The combination of these two has jointly achieved the efficient and specific removal of cytokine. This innovative material is the only reported artificial biomaterial capable of selectively eliminating multiple cytokines under conditions close to clinical practice. It has the potential to improve outcomes for patients with hypercytokinemia and reduce the risk of adverse events associated with current treatment modalities.

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.

Simplified regional citrate anticoagulation protocol for CVVH, CVVHDF and SLED focused on the prevention of KRT-related hypophosphatemia while optimizing acid-base balance

BACKGROUND

Hypophosphatemia is a common electrolyte disorder in critically ill patients undergoing prolonged kidney replacement therapy (KRT). We evaluated the efficacy and safety of a simplified regional citrate anticoagulation (RCA) protocol for continuous venovenous hemofiltration (CVVH), continuous venovenous hemodiafiltration (CVVHDF) and sustained low-efficiency dialysis filtration (SLED-f). We aimed at preventing KRT-related hypophosphatemia while optimizing acid-base equilibrium.

METHODS

KRT was performed by the Prismax system (Baxter) and polyacrylonitrile AN69 filters (ST 150, 1.5 m2, Baxter), combining a 18 mmol/L pre-dilution citrate solution (Regiocit 18/0, Baxter) with a phosphate-containing solution (HPO42- 1.0 mmol/L, HCO3- 22.0 mmol/L; Biphozyl, Baxter). When needed, phosphate loss was replaced with sodium glycerophosphate pentahydrate (Glycophos™ 20 mmol/20 mL, Fresenius Kabi Norge AS, Halden, Norway). Serum citrate measurements were scheduled during each treatment. We analyzed data from three consecutive daily 8-h SLED-f sessions, as well as single 72-h CVVH or 72-h CVVHDF sessions. We used analysis of variance (ANOVA) for repeated measures to evaluate differences in variables means (i.e. serum phosphate, citrate). Because some patients received phosphate supplementation, we performed analysis of covariance (ANCOVA) for repeated measures modelling phosphate supplementation as a covariate.

RESULTS

Forty-seven patients with acute kidney injury (AKI) or end stage kidney disease (ESKD) requiring KRT were included [11 CVVH, 11 CVVHDF and 25 SLED-f sessions; mean Acute Physiology and Chronic Health Evaluation II (APACHE II) score 25 ± 7.0]. Interruptions for irreversible filter clotting were negligible. The overall incidence of hypophosphatemia (s-P levels <2.5 mg/dL) was 6.6%, and s-P levels were kept in the normality range irrespective of baseline values and the KRT modality. The acid-base balance was preserved, with no episode of citrate accumulation.

CONCLUSIONS

Our data obtained with a new simplified RCA protocol suggest that it is effective and safe for CVVH, CVVHDF and SLED, allowing to prevent KRT-related hypophosphatemia and maintain the acid-base balance without citrate accumulation.

TRIAL REGISTRATION

NCT03976440 (registered 6 June 2019).

Austrian consensus on the diagnosis and management of portal hypertension in advanced chronic liver disease (Billroth IV)

The Billroth IV consensus was developed during a consensus meeting of the Austrian Society of Gastroenterology and Hepatology (ÖGGH) and the Austrian Society of Interventional Radiology (ÖGIR) held on the 26th of November 2022 in Vienna.Based on international recommendations and considering recent landmark studies, the Billroth IV consensus provides guidance regarding the diagnosis and management of portal hypertension in advanced chronic liver disease.

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.

Impact of Transfused Citrate on Pathophysiology in Massive Transfusion

This narrative review article seeks to highlight the effects of citrate on physiology during massive transfusion of the bleeding patient.

DATA SOURCES

A limited library of curated articles was created using search terms including "citrate intoxication," "citrate massive transfusion," "citrate pharmacokinetics," "hypocalcemia of trauma," "citrate phosphate dextrose," and "hypocalcemia in massive transfusion." Review articles, as well as prospective and retrospective studies were selected based on their relevance for inclusion in this review.

STUDY SELECTION

Given the limited number of relevant studies, studies were reviewed and included if they were written in English. This is not a systematic review nor a meta-analysis.

DATA EXTRACTION AND SYNTHESIS

As this is not a meta-analysis, new statistical analyses were not performed. Relevant data were summarized in the body of the text.

CONCLUSIONS

The physiologic effects of citrate independent of hypocalcemia are poorly understood. While a healthy individual can rapidly clear the citrate in a unit of blood (either through the citric acid cycle or direct excretion in urine), the physiology of hemorrhagic shock can lead to decreased clearance and prolonged circulation of citrate. The so-called "Diamond of Death" of bleeding-coagulopathy, acidemia, hypothermia, and hypocalcemia-has a dynamic interaction with citrate that can lead to a death spiral. Hypothermia and acidemia both decrease citrate clearance while circulating citrate decreases thrombin generation and platelet function, leading to ionized hypocalcemia, coagulopathy, and need for further transfusion resulting in a new citrate load. Whole blood transfusion typically requires lower volumes of transfused product than component therapy alone, resulting in a lower citrate burden. Efforts should be made to limit the amount of citrate infused into a patient in hemorrhagic shock while simultaneously addressing the induced hypocalcemia.

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.

Evaluation of the registry DIALYREG for the assessment of continuous renal replacement techniques in the critically ill patient

Continuous renal replacement techniques (CRRT) can induce complications and monitoring is crucial to ensure patient safety. We designed a prospective multicenter observational and descriptive study using the DIALYREG registry, an online database located on a REDCap web-based platform that allows real-time data analysis. Our main objective was to identify CRRT-related complications in our intensive care units (ICUs) and implement security measures accordingly. From January 2019 to December 2020, we included 323 patients with admission diagnoses of medical illness (54%), sepsis (24%), postoperative care (20%), and trauma (2%). CRRT indications were homeostasis (42%), oliguria (26%), fluid overload (15%), and hemodynamic optimization (13%). The median initial therapy dose was 30 ml/kg/h (IQR 25-40), and dynamic adjustment was performed in 61% of the treatments. Sets were anticoagulated with heparin (40%), citrate (38%) or no anticoagulation (22%). Citrate anticoagulation had several advantages: more frequent dynamic CRRT dose adjustment (77% vs. 58% with heparin and 56% without anticoagulation, p < 0.05), longer duration of set (median of 55 h, IQR 24-72 vs. 23 h, IQR 12-48 with heparin and 12 h, IQR 12-31 without anticoagulation, p < 0.05), less clotting of the set (26% vs. 46.7% with heparin, p < 0.05), and lower incidence of hypophosphatemia (1% citrate vs. 6% with heparin and 5% without anticoagulation). It was also safe and effective in subgroup analysis of patients with liver disease or sepsis. The main global complications were hypothermia (16%), hypophosphatemia (13%) and metabolic acidosis (10%). Weaning of the therapy was achieved through early discontinuation (56%), nocturnal therapy transition (26%) and progressive SLED (18%). 52% of the patients were discharged from the hospital, while 43% died in the ICU and 5% died during hospitalization. We can conclude that the DIALYREG registry is a feasible tool for real-time control of CRRT in our ICU.

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.

Pharmacological methods for blood stabilization in the extracorporeal circuit (review of literature)

We summarize the possible benefits and risks of using various anticoagulants during hemoperfusion. Clotting in the extracorporeal circuit can lead to a decrease in the effectiveness of therapy,  additional workload,  risk to the patient and economic losses. At the same time, relatively excessive anticoagulation against the background of existing hemostasis  disorders  can lead to severe hemorrhagic complications, which in turn  worsen the prognosis of patients. The article describes the causes of heparin resistance, the main techniques for overcoming it, and provides practical guidelines for anticoagulant therapy during hemoperfusion. It is well known that routine methods of monitoring hemostasis (such as platelet count, activated partial thromboplastin time) are unable to assess the balance of pro/anticoagulants. The authors have proposed a reasonable personalized approach to anticoagulant therapy  of extracorporeal blood purification depending  on the pathology  in patient and thromboelastography (TEG) data, and antithrombin III levels.

Continuous KRT: A Contemporary Review

AKI is a common complication of critical illness and is associated with substantial morbidity and risk of death. Continuous KRT comprises a spectrum of dialysis modalities preferably used to provide kidney support to patients with AKI who are hemodynamically unstable and critically ill. The various continuous KRT modalities are distinguished by different mechanisms of solute transport and use of dialysate and/or replacement solutions. Considerable variation exists in the application of continuous KRT due to a lack of standardization in how the treatments are prescribed, delivered, and optimized to improve patient outcomes. In this manuscript, we present an overview of the therapy, recent clinical trials, and outcome studies. We review the indications for continuous KRT and the technical aspects of the treatment, including continuous KRT modality, vascular access, dosing of continuous KRT, anticoagulation, volume management, nutrition, and continuous KRT complications. Finally, we highlight the need for close collaboration of a multidisciplinary team and development of quality assurance programs for the provision of high-quality and effective continuous KRT.

Cirrhosis Management in the Intensive Care Unit

Patients with cirrhosis frequently require admission to the intensive care unit as complications arise in the course of their disease. These admissions are associated with high short- and long-term morbidity and mortality. Thus, understanding and characterizing complications and unique needs of patients with cirrhosis and acute-on-chronic liver failure helps providers identify appropriate level of care and evidence-based treatments. While there is no widely accepted critical care admission criteria for patients with cirrhosis, the presence of organ failure and primary or nosocomial infections are associated with particularly high in-hospital mortality. Optimal management of patients with cirrhosis in the critical care setting requires a system-based approach that acknowledges deviations from canonical pathophysiology. In this review, we discuss appropriate considerations and evidence-based practices for the general care of patients with cirrhosis and critical illness.

Regional Citrate Anticoagulation or Heparin Anticoagulation for Renal Replacement Therapy in Patients With Liver Failure: A Systematic Review and Meta-Analysis

In patients with liver failure complicated by acute kidney injury, renal replacement therapy (RRT) is often required to improve the internal environment. The use of anticoagulants for RRT in patients with liver failure remains controversial. We searched the PubMed, Embase, Cochrane Library, and Web of Science databases for studies. The methodological quality of the included studies was assessed using the Methodological Index for Nonrandomized Studies. A meta-analysis was performed using R software (version 3.5.1) and Review Manager (version 5.3.5). During RRT, 348 patients from 9 studies received regional citrate anticoagulation (RCA), and 127 patients from 5 studies received heparin anticoagulation (including heparin and LMWH). Among patients who received RCA, the incidence of citrate accumulation, metabolic acidosis, and metabolic alkalosis were 5.3% (95% confidence interval [CI]: 0%-25.3%), 26.4% (95% CI: 0-76.9), and 1.8% (95% CI: 0-6.8), respectively. The potassium, phosphorus, total bilirubin (TBIL), and creatinine levels were lower, whereas the serum pH, bicarbonate, base excess levels, and total calcium/ionized calcium ratio were higher after treatment than before treatment. Among patients who received heparin anticoagulation, the TBIL levels were lower, whereas the activated partial thromboplastin clotting time and D-dimer levels were higher after treatment than before treatment. The mortality rates in the RCA and heparin anticoagulation groups were 58.9% (95% CI: 39.2-77.3) and 47.4% (95% CI: 31.1-63.7), respectively. No statistical difference in mortality was observed between the 2 groups. For patients with liver failure, the administration of RCA or heparin for anticoagulation during RRT under strict monitoring may be safe and effective.

Comparison of nafamostat mesilate to citrate anticoagulation in pediatric continuous kidney replacement therapy

BACKGROUND

Regional citrate anticoagulation (RCA) is the preferred continuous kidney replacement therapy (CKRT) anticoagulation strategy for children in the USA. Nafamostat mesilate (NM), a synthetic serine protease, is used widely for CKRT anticoagulation in Japan and Korea. We compared the safety and efficacy of NM to RCA for pediatric CKRT.

METHODS

Starting June 2019, the most recent 100 medical records of children receiving CKRT with either RCA or NM were reviewed retrospectively, at one children's hospital in Japan (NM) and one in the USA (RCA). The number of hours a single CKRT filter was in use, was the primary outcome. Safety was assessed by bleeding complications for the NM group and citrate toxicity leading to RCA discontinuation or electrolyte imbalance in the RCA group.

RESULTS

Eighty patients received NM and 78 patients received RCA. Median filter life was longer for the NM group (NM: 38 [22, 74] vs. RCA: 36 [17, 66] h, p = 0.02). When filter life was censored for discontinuation other than clotting, the 60-h survival rate was higher for RCA (71% vs. 54%). The hazard ratio comparing NM over RCA varied over time (HR 0.7; 0.2-1.5, p = 0.33 at 0 h to HR 5.5; 1.3-23.7, p = 0.334 at 72 h). The lack of difference in filter survival persisted controlling for filter surface area, catheter diameter, and pre-CKRT platelet count. Major bleeding rates did not differ between groups (NM: 5% vs. RCA: 9%).

CONCLUSIONS

RCA and NM provide satisfactory anticoagulation for CKRT in children with no difference in major bleeding rates. A higher resolution version of the Graphical abstract is available as Supplementary information.

Calcium-containing versus calcium-free replacement solution in regional citrate anticoagulation for continuous renal replacement therapy: a randomized controlled trial

BACKGROUND

A simplified protocol for regional citrate anticoagulation (RCA) using a commercial calcium-containing replacement solution, without continuous calcium infusion, is more efficient for use in continuous renal replacement therapy (CRRT). We aim to design a randomized clinical trial to compare the safety and efficacy between calcium-free and calcium-containing replacement solutions in CRRT with RCA.

METHODS

Of the 64 patients receiving RCA-based postdilution continuous venovenous hemodiafiltration (CVVHDF) enrolled from 2017 to 2019 in West China Hospital of Sichuan University, 35 patients were randomized to the calcium-containing group and 29 to the calcium-free replacement solution group. The primary endpoint was circuit lifespan and Kaplan-Meier survival analysis was performed. Secondary endpoints included hospital mortality, kidney function recovery rate, and complications. The amount of 4% trisodium citrate solution infusion was recorded. Serum and effluent total (tCa) and ionized (iCa) calcium concentrations were measured during CVVHDF.

RESULTS

A total of 149 circuits (82 in the calcium-containing group and 67 in the calcium-free group) and 7609 circuit hours (4335 h vs. 3274 h) were included. The mean circuit lifespan was 58.1 h (95% CI 53.8-62.4 h) in the calcium-containing group vs. 55.3 h (95% CI 49.7-60.9 h, log rank P = 0.89) in the calcium-free group. The serum tCa and iCa concentrations were slightly lower in the calcium-containing group during CRRT, whereas the postfilter iCa concentration was lower in the calcium-free group. Moreover, the mean amounts of 4% trisodium citrate solution infusion were not significantly different between the groups (171.1 ± 15.9 mL/h vs. 169.0 ± 15.1 mL/h, P = 0.49). The mortality (14/35 [40%] vs. 13/29 [45%], P = 0.70) and kidney function recovery rates of AKI patients (19/26, 73% vs. 14/24, 58%, P = 0.27) were comparable between the calcium-containing and calcium-free group during hospitalization, respectively. Six (three in each group) patients showed signs of citrate accumulation in this study.

CONCLUSIONS

When compared with calcium-free replacement solution, RCA-based CVVHDF with calcium-containing replacement solution had a similar circuit lifespan, hospital mortality and kidney outcome. Since the calcium-containing solution obviates the need for a separate venous catheter and a large dose of intravenous calcium solution preparation for continuous calcium supplementation, it is more convenient to be applied in RCA-CRRT practice.

REGISTRATION

Chinese Clinical Trial Registry (www.chictr.org.cn, ChiCTR-IPR-17012629).

The conundrum of the complex relationship between acute kidney injury and cardiac arrhythmias

Acute kidney injury (AKI) is defined by a rapid increase in serum creatinine levels, reduced urine output, or both. Death may occur in 16%-49% of patients admitted to an intensive care unit with severe AKI. Complex arrhythmias are a potentially serious complication in AKI patients with pre-existing or AKI-induced heart damage and myocardial dysfunction, fluid overload, and especially electrolyte and acid-base disorders representing the pathogenetic mechanisms of arrhythmogenesis. Cardiac arrhythmias, in turn, increase the risk of poor renal outcomes, including AKI. Arrhythmic risk in AKI patients receiving kidney replacement treatment may be reduced by modifying dialysis/replacement fluid composition. The most common arrhythmia observed in AKI patients is atrial fibrillation. Severe hyperkalemia, sometimes combined with hypocalcemia, causes severe bradyarrhythmias in this clinical setting. Although the likelihood of life-threatening ventricular arrhythmias is reportedly low, the combination of cardiac ischemia and specific electrolyte or acid-base abnormalities may increase this risk, particularly in AKI patients who require kidney replacement treatment. The purpose of this review is to summarize the available epidemiological, pathophysiological, and prognostic evidence aiming to clarify the complex relationships between AKI and cardiac arrhythmias.

Utility of Citrate Dialysis in Patients with Contraindication for Heparin in a Limited-Resource Setting

Background: Hemodialysis among critical care patients with acute kidney injury (AKI) is challenging, especially if heparin is contraindicated. Objectives: This study assessed the utility of citrate dialysis for such patients in a limited-resource setting. Methods: In this prospective study, patients were divided into group A (heparin-free saline flush dialysis), group B (heparin-free citrate dialysis without flushing), and group C (heparin-free citrate dialysis with flushing). The subjects underwent completed sustained low-efficiency daily dialysis (blood flow = 150 mL/minute, dialysate = 300 mL/minute) or intermittent hemodialysis (blood flow = 250 mL/minute, dialysate flow = 500 mL/minute). Statistical tests using SPSS software (version 26) were used to determine safety and effectiveness differences. Results: Among 25 patients studied with multiple hemodialysis sessions, blood flow and dialysate flow were observed to be better in heparin-free citrate dialysis with flushing. There were further advantages of lesser dialyzer clotting and more reuse of dialyzers. Metabolic differences were insignificant. Heparin-free citrate dialysis with or without flushing was equally effective and safe, compared to heparin-free saline flush dialysis, in patients with or without liver impairment. Conclusions: Citrate dialysis is observed to be a safe and effective alternative to heparin-free saline flushing dialysis in intensive care unit patients with AKI. More such studies are required in limited-resource settings to utilize citrate dialysis in patients with heparin contraindication.

Management of hepatorenal syndrome in liver cirrhosis: a recent update

Hepatorenal syndrome (HRS) is a serious form of renal dysfunction in patients with cirrhosis and ascites. It is an important component of the acute-on-chronic liver failure (ACLF) syndrome. Significant recent changes in the understanding of the pathophysiology of renal dysfunction in cirrhosis include the role of inflammation in addition to hemodynamic changes. The term acute kidney injury (AKI) is now adopted to include all functional and structural forms of acute renal dysfunction in cirrhosis, with various stages describing the severity of the condition. Type 1 hepatorenal syndrome (HRS1) is renamed HRS-AKI, which is stage 2 AKI [doubling of baseline serum creatinine (sCr)] while fulfilling all other criteria of HRS1. Albumin is used for its volume expanding and anti-inflammatory properties to confirm the diagnosis of HRS-AKI. Vasoconstrictors are added to albumin as pharmacotherapy to improve the hemodynamics. Terlipressin, although not yet available in North America, is the most common vasoconstrictor used worldwide. Patients with high grade of ACLF treated with terlipressin are at risk for respiratory failure if there is pretreatment respiratory compromise. Norepinephrine is equally effective as terlipressin in reversing HRS1. Recent data show that norepinephrine may be administered outside the intensive care setting, but close monitoring is still required. There has been no improvement in overall or transplant-free survival shown with vasoconstrictor use, but response to vasoconstrictors with reduction in sCr is associated with improvement in survival. Non-responders to vasoconstrictor plus albumin will need liver transplantation as definite treatment with renal replacement therapy as a bridge therapy. Combined liver and kidney transplantation is recommended for patients with prolonged history of AKI, underlying chronic kidney disease or with hereditary renal conditions. Future developments, such as the use of biomarkers and metabolomics, may help to identify at risk patients with earlier diagnosis to allow for earlier treatment with improved outcomes.

Continuous Renal Replacement Therapy with Regional Citrate Anticoagulation in Children with Liver Dysfunction/Failure

Regional citrate anticoagulation (RCA) is an option but citrate accumulation is risk and it is a giving up cause for this situation. This retrospective study was conducted in the pediatric intensive care unit (PICU) between May 2019 and April 2021. We investigated 47 patients with liver failure (LF) in our PICU, and RCA during continuous renal replacement therapy (CRRT) was applied to 10 (21.3%) of them. Half of them were male (n: 5/10), their mean age was 104.7 ± 66.20 months. Nine of them needed vasoactive support during follow-up. The most common indication for CRRT was hepatorenal syndrome (40%). There was no significant difference between liver transaminases and liver function tests before and after CRRT (p > 0.05). In terms of citrate toxicity of the patients, there was no significant difference between total calcium/ionized calcium, lactate level, pH and bicarbonate values before and after CRRT (p > 0.05). The mean total CRRT time was 110.2 ± 118.2 h, and the mean circuit lifespan was 43.8 ± 48.7 h; the mean number of circuits was 2.7 ± 2.4. Total Ca/ionized Ca >2.5 was a clinically relevant endpoint, but no patient interrupted dialysis for this cause. There was no complication about RCA. This study did not observe any adverse effects on acid-base status, transaminases, an increase in bilirubin during RCA-CRRT treatment in pediatric patients with LF. Total calcium/ionized calcium ratio, serum lactate level and prothrombin time level should be closely monitored daily in terms of citrate accumulation in this patient group.

Kidney Replacement Therapy in Patients with Acute Liver Failure and End-Stage Cirrhosis Awaiting Liver Transplantation

Providing dialysis to patients with liver failure is challenging because of their tenuous hemodynamics and refractory ascites. With better machinery and increased availability, continuous kidney replacement therapy has been successfully delivered to acutely ill patients in liver failure over the past few decades. Intermittent hemodialysis continues to remain the modality of choice outside the intensive care unit and on occasion needs to be complemented with paracentesis. Peritoneal dialysis has not been widely used, but recent literature shows promising outcomes barring for publication bias. Albumin dialysis could be a lifesaving procedure for a carefully selected subgroup of patients with liver failure.

Review of Anticoagulation in Continuous Renal Replacement Therapy

Continuous renal replacement therapy is an important, yet challenging, treatment of critically ill patients with kidney dysfunction. Clotting within the dialysis filter or circuit leads to time off therapy and impaired delivery of prescribed treatment. Anticoagulation can be used to prevent this complication; however, doing so introduces risk for unintended complications such as bleeding or metabolic derangements in patients who are already critically ill. A thorough understanding of indications, therapeutic options, and monitoring principles is necessary for safe and effective use of this strategy. This review provides clinicians important information regarding when to anticoagulate, differences in pharmacologic agents, recommended doses, routes of drug delivery, and appropriate laboratory monitoring for patients receiving anticoagulation to support continuous renal replacement therapy.

Citrate pharmacokinetics in critically ill liver failure patients receiving CRRT

Citrate has been proposed as anticoagulation of choice in continuous renal replacement therapy (CRRT). However, little is known about the pharmacokinetics (PK) and metabolism of citrate in liver failure patients who require CRRT with regional citrate anticoagulation (RCA). This prospective clinical PK study was conducted at King Chulalongkorn Memorial Hospital between July 2019 to April 2021, evaluating seven acute liver failure (ALF) and seven acute-on-chronic liver failure (ACLF) patients who received CRRT support utilizing RCA as an anticoagulant at a citrate dose of 3 mmol/L. For evaluation of the citrate PK, we delivered citrate for 120 min and then stopped for a further 120 min. Total body clearance of citrate was 152.5 ± 50.9 and 195.6 ± 174.3 mL/min in ALF and ACLF, respectively. The ionized calcium, ionized magnesium, and pH slightly decreased after starting citrate infusion and gradually increased to baseline after stopping citrate infusion. Two of the ACLF patients displayed citrate toxicity during citrate infusion, while, no ALF patient had citrate toxicity. In summary, citrate clearance was significantly decreased in critically ill ALF and ACLF patients receiving CRRT. Citrate use as an anticoagulation in these patients is of concern for the risk of citrate toxicity.

Management of acute renal replacement therapy in critically ill cirrhotic patients

Renal replacement therapy (RRT) in cirrhotic patients encompasses a number of issues related to the particular characteristics of this population, especially in the intensive care unit (ICU) setting. The short-term prognosis of cirrhotic patients with acute kidney injury is poor, with a mortality rate higher than 65% in patients with RRT requirement, raising questions about the futility of its initiation. Regarding the management of the RRT itself, there is still no consensus with respect to the modality (continuous versus intermittent) or the anticoagulation required to improve the circuit life, which is shorter than similar at-risk populations, despite the altered haemostasis in traditional coagulation tests frequently found in these patients. Furthermore, volume management is one of the most complex issues in this cohort, where tools used for ambulatory dialysis have not yet been successfully reproducible in the ICU setting. This review attempts to shed light on the management of acute RRT in the critically ill cirrhotic population based on the current evidence and the newly available tools. We will discuss the timing of RRT initiation and cessation, the modality, anticoagulation and fluid management, as well as the outcomes of the RRT in this population, and provide a brief review of the albumin extracorporeal dialysis from the point of view of a nephrologist.

Clinical application of regional citrate anticoagulation for continuous renal replacement therapy in children with liver injury

BACKGROUND

Regional citrate anticoagulation (RCA) is increasingly used for continuous renal replacement therapy (CRRT) in children, but it is rarely used in children with liver injury, especially liver failure (LF). We analyze this issue through the following research.

METHODS

We retrospectively analyzed 75 children with liver injury who underwent RCA-CRRT in the Pediatric Intensive Care Unit (PICU) of Children's Hospital of Chongqing Medical University. The patients were divided into the LF group and liver dysfunction (LD) group. The two groups were compared to evaluate the clinical safety and efficacy of RCA-CRRT in children with liver injury and to explore RCA-CRRT management strategies, in terms of the following indicators: the incidence of bleeding, clotting, citrate accumulation (CA), acid-base imbalance, and electrolyte disturbance, as well as filter lifespans, changes in biochemical indicators, and CRRT parameters adjustment.

RESULTS

The total incidence of CA (TCA) and persistent CA (PCA) in the LF group were significantly higher than those in the LD group (38.6 vs. 16.2%, p < 0.001; 8.4 vs. 1.5%, p < 0.001); and the CA incidence was significantly reduced after adjustment both in the LF (38.6 vs. 8.4%, p < 0.001) and LD groups (16.2 vs. 1.5%, p < 0.001). The incidence of hypocalcemia was significantly higher in the LF group than in the LD group either before (34.9 vs. 8.8%, p < 0.001) or after treatment (12.0 vs. 0%, p < 0.001). The speed of the blood and citrate pumps after adjustment was lower than the initial setting values in both the LF and LD groups. The dialysis speed plus replacement speed were higher than the initial settings parameters.

CONCLUSION

For children undergoing RCA-CRRT, the risks of CA and hypocalcemia are significantly higher in children with liver failure than those with liver dysfunction, but through the proper adjustment of the protocol, RCA-CRRT can still be safely and effectively approached for children with LD and even LF.

Hemorrhage and venous thromboembolism in critically ill patients with COVID-19

Objective:

The majority of patients with COVID-19 showed mild symptoms. However, approximately 5% of them were critically ill and require intensive care unit admission for advanced life supports. Patients in the intensive care unit were high risk for venous thromboembolism and hemorrhage due to the immobility and anticoagulants used during advanced life supports. The aim of the study was to report the incidence and treatments of the two complications in such patients.

Method:

Patients with COVID-19 (Group 1) and patients with community-acquired pneumonia (Group 2) that required intensive care unit admission were enrolled in this retrospective study. Their demographics, laboratory results, ultrasound findings and complications such as venous thromboembolism and hemorrhage were collected and compared.

Results:

Thirty-four patients with COVID-19 and 51 patients with community-acquired pneumonia were included. The mean ages were 66 and 63 years in Groups 1 and 2, respectively. Venous thromboembolism was detected in 6 (18%) patients with COVID-19 and 18 (35%) patients with community-acquired pneumonia (P = 0.09). The major type was distal deep venous thrombosis. Twenty-one bleeding events occurred in 12 (35%) patients with COVID-19 and 5 bleeding events occurred in 5 (10%) patients with community-acquired pneumonia, respectively (P = 0.01). Gastrointestinal system was the most common source of bleeding. With the exception of one death due to intracranial bleeding, blood transfusion with or without surgical/endoscopic treatments was able to manage the bleeding in the remaining patients. Multivariable logistic regression showed increasing odds of hemorrhage with extracorporeal membrane oxygenation (odds ratio: 13.9, 95% confidence interval: 4.0–48.1) and COVID-19 (odds ratio: 4.7, 95% confidence interval: 1.2–17.9).

Conclusion:

Venous thromboembolism and hemorrhage were common in both groups. The predominant type of venous thromboembolism was distal deep venous thrombosis, which presented a low risk of progression. COVID-19 and extracorporeal membrane oxygenation were risk factors for hemorrhage. Blood transfusion with or without surgical/endoscopic treatments was able to manage it in most cases.

Electrolyte monitoring during regional citrate anticoagulation in continuous renal replacement therapy

Patients with acute kidney injury who need continuous renal replacement therapy with locoregional citrate anticoagulation are at risk of citrate accumulation with disruption of the calcium balance. We aimed to evaluate the safety of detecting citrate accumulation and adjusting electrolyte disbalances during continuous venovenous hemodialysis (CVVHD) in critically ill patients with acute kidney injury using a blood sample frequency every 6 h. A prospective single center study in critically ill intensive care unit patients who suffered from acute kidney injury with the need of renal replacement therapy. We evaluated the deviations in pH, bicarbonate and calcium during CVVHD treatment with local regional citrate anticoagulation. Values indicate median and interquartile range. Severe hypocalcemia (below 1.04 mmol/L) or hypercalcemia (above 1.31 mmol/L) occurred in 10.5% and 4.8% respectively. During treatment changes of systemic ionized calcium, post-filter ionized calcium, pH and bicarbonate were corrected with protocolized adjustments. No arrhythmias or citrate accumulation were seen. The values stabilized after 42 h and after that no statistically significant changes were observed. After 42 h of citrate CVVHD, systemic ionized calcium, pH and bicarbonate levels stabilized. A blood sample frequency every 6 h is probably safe to detect citrate accumulation and to adjust the settings of electrolytes to avoid serious electrolyte disturbances in ICU patients without severe metabolic acidosis or severe liver failure.

Development of a Multivariable Prediction Model for Citrate Accumulation in Liver Transplant Patients Undergoing Continuous Renal Replacement Therapy with Regional Citrate Anticoagulation

INTRODUCTION

Patients with impaired citrate metabolism may experience citrate accumulation (CA), which causes life-threatening metabolic acidosis and hypocalcemia. CA poses a challenge for clinicians when deciding on the use of regional citrate anticoagulation (RCA) for patients with liver dysfunction. This study aimed to develop a prediction model integrating multiple clinical variables to assess the risk of CA in liver transplant patients.

METHODS

This single-center prospective cohort study included postoperative liver transplant patients who underwent continuous renal replacement therapy (CRRT) with RCA. The study end point was CA. A prediction model was developed using a generalized linear mixed-effect model based on the Akaike information criterion. The predictive values were assessed using the receiver operating characteristic curve and bootstrap resampling (times = 500) to estimate the area under the curve (AUC) and the corresponding 95% confidence interval (CI). A nomogram was used to visualize the model.

RESULTS

This study included 32 patients who underwent 133 CRRT sessions with RCA. CA occurred in 46 CRRT sessions. The model included lactate, norepinephrine >0.1 μg/kg/min, alanine aminotransferase, total bilirubin, and standard bicarbonate, which were tested before starting each CRRT session and body mass index, diabetes mellitus, and chronic kidney disease as predictors. The AUC of the model was 0.867 (95% CI 0.786-0.921), which was significantly higher than that of the single predictor (p < 0.05). A nomogram visualized the prediction model.

CONCLUSIONS

The prediction model integrating multiple clinical variables showed a good predictive value for CA. A nomogram visualized the model for easy application in clinical practice.

Regional Citrate Anticoagulation for Continuous Kidney Replacement Therapy With Calcium-Containing Solutions: A Cohort Study

OBJECTIVE

Regional citrate anticoagulation (RCA) is the preferred anticoagulation method for continuous kidney replacement therapy (CKRT) recommended by KDIGO. Limited availability of calcium-free solutions often imposes challenges to the implementation of RCA for CKRT (RCA-CKRT). The principal purpose of this study was to characterize the outcomes of RCA-CKRT using calcium-containing solutions.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

We evaluated the safety and efficacy of RCA-CKRT with calcium-containing dialysate and replacement fluid used for 128 patients. A total of 571 filters and 1,227 days of CKRT were analyzed.

EXPOSURES

Liver disease, sepsis in the absence of liver disease, and sepsis with liver disease.

OUTCOMES

Filter life and metabolic complications per 100 CKRT days.

ANALYTICAL APPROACH

Linear mixed-effects model and generalized linear mixed-effects models.

RESULTS

The majority of patients were male (91; 71.1%), 32 (25%) had liver disease, and 29 (22.7%) had sepsis without liver disease. Median filter life was 50.0 (interquartile range, 22.0-118.0) hours, with a maximum of 322 hours, and was significantly lower (33.5 [interquartile range, 17.5-60.5] h) in patients with liver disease. Calcium-containing replacement solutions were used in 41.6% of all CKRT hours and reduced intravenous calcium requirements by 31.7%. Hypocalcemia (ionized calcium<0.85mmol/L) and hypercalcemia (total calcium>10.6mg/dL) were observed in 6.0 and 6.7 per 100 CKRT days, respectively. Citrate accumulation was observed in 13.3% of all patients and was associated with metabolic acidosis in 3.9%, which was not significantly different in patients with liver disease (9.3%; P = 0.2).

LIMITATIONS

Lack of control groups that used calcium-free dialysate and replacement solutions with RCA-CKRT. Possible overestimation of filter life from incomplete data on cause of filter failure.

CONCLUSIONS

Our study suggests that RCA-CKRT with calcium-containing solutions is feasible and safe in critically ill patients, including those with sepsis and liver disease.

Anticoagulation strategies in continuous renal replacement therapy

The most common anticoagulant options for continuous renal replacement therapy (CRRT) include unfractionated heparin (UFH), regional citrate anticoagulation (RCA), and no anticoagulation. Less common anticoagulation options include UFH with protamine reversal, low-molecular weight heparin (LMWH), thrombin antagonists, and platelet inhibiting agents. The choice of anticoagulant for CRRT should be determined by patient characteristics, local expertise, and ease of monitoring. The Kidney Disease Improving Global Outcomes (KDIGO) acute kidney injury guidelines recommend using RCA rather than UFH in patients who do not have contraindications to citrate and are with or without increased risk of bleeding. Monitoring should include evaluation of the anticoagulant effect, circuit life, filter efficacy, and complications.

Renal replacement therapy in critically ill patients with acute kidney injury: 2020 nephrologist's perspective

Renal replacement therapies (RRT) as support for acute kidney injury in critically ill patients have become a routine and essential practice in their management, resulting in the widespread use of various techniques among these patients, such as intermittent hemodialysis (IHD), extended hemodialysis and continuous RRT (CRRT). In this review we aim to summarize current evidence of indication, choice of modality, timing of initiation, dosing and technical aspects of RRT. We carried out a narrative review based on guidelines, consensus documents by main working groups and the latest relevant clinical trials on RRT in the critically ill. We did not find enough evidence of any RRT modality having superior benefits in terms of patient survival, length of intensive care unit/hospital stay or renal outcomes among critically ill patients, in spite of optimization of clinical indication, modality, timing of initiation and intensity of initial therapy. This is still a controverted matter, since only early start of high-flux CRRT has been proven beneficial over IHD among hemodynamically unstable postoperative patients. Our objective is to portrait current RRT practices in multidisciplinary management of critically ill patients by intensive care and nephrology professionals. Implication of a nephrologist in the assessment of hemodynamic status, coexisting medical conditions, renal outcome expectations and management of resources could potentially have benefits at the time of RRT selection and troubleshooting.

Continuous Renal Replacement Therapy: A Review of Use and Application in Pediatric Hematopoietic Stem Cell Transplant Recipients

Hematopoietic stem cell transplant (HSCT) is a curative therapy for malignant and non-malignant conditions. However, complications post-HSCT contribute to significant morbidity and mortality in this population. Acute kidney injury (AKI) is common in the post-allogeneic transplant phase and contributes to morbidity in this population. Continuous renal replacement therapy (CRRT) is used often in the setting of AKI or multiorgan dysfunction in critically ill children. In addition, CRRT can be useful in many disease processes related to transplant and can potentially improve outcomes in this population. This review will focus on the use of CRRT in critically ill children in the post-HSCT setting outside the realm of acute renal failure and highlight the benefits and applications of this modality in this high-risk population.

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

BACKGROUND

Continuous renal replacement therapy (CRRT) with regional citrate anticoagulation (RCA) is now commonly used to treat acute kidney injury in critically ill patients. The concentration of citrate is not routinely measured, with citrate accumulation and/or toxicity primarily assessed using surrogate measures.

OBJECTIVES

The aim of this study was to measure the concentration of citrate in plasma and ultrafiltrate in patients receiving CRRT with RCA using a modified commercial enzymatic assay.

METHODS

After meeting inclusion criteria, blood was sampled from 20 patients before, during, and after episodes of filtration. Using spectrophotometry, samples were tested for citrate concentration. Demographic and other clinical and biochemical data were also collected. Throughout, a 15 mmol/L solution of trisodium citrate was used as the prefilter anticoagulant. Results were analysed using STATA (v15.0) and presented as mean (SD), median (IQR), or simple proportion. Comparisons were made using either the Student t test or the Wilcoxon rank-sum test. Correlation was assessed using Pearson's r.

RESULTS

Twenty patients (17 males) were enrolled in the study. Mean (SD) age was 63.7 years (9.9). Median (IQR) ICU length of stay was 281 h (199, 422) with 85% undergoing intermittent positive pressure ventilation. Median APACHE 3 score was 95 (87, 117) with an overall 30% mortality rate. Median filtration time was 85 h (46, 149). No difference was found between pre- and post-filtration plasma citrate concentrations (79 µmol/L [50] vs. 71 µmol/L [42], p = 0.65). Mean citrate concentration during filtration was 508 µmol/L (221) with a maximum of 1,070 µmol/L. This was significantly higher than the pre/post levels (p < 0.001).

CONCLUSIONS

Plasma concentrations of citrate rose significantly during episodes of CRRT using RCA returning back to normal after cessation of treatment.