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

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 .

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.

Liver-Support Therapies in Critical Illness-A Comparative Analysis of Procedural Characteristics and Safety

Extracorporeal liver-support therapies remain controversial in critically ill patients, as most studies have failed to show an improvement in outcomes. However, heterogeneous timing and inclusion criteria, an insufficient number of treatments, and the lack of a situation-dependent selection of available liver-support modalities may have contributed to negative study results. We retrospectively investigated the procedural characteristics and safety of the three liver-support therapies CytoSorb, Molecular Adsorbent Recirculating System (MARS) and therapeutic plasma exchange (TPE). Whereas TPE had its strengths in a shorter treatment duration, in clearing larger molecules, affecting platelet numbers less, and improving systemic coagulation and hemodynamics, CytoSorb and MARS were associated with a superior reduction in particularly small protein-bound and water-soluble substances. The clearance magnitude was concentration-dependent for all three therapies, but additionally related to the molecular weight for CytoSorb and MARS therapy. Severe complications did not appear. In conclusion, a better characterization of disease-driving as well as beneficial molecules in critically ill patients with acute liver dysfunction is crucial to improve the use of liver-support therapy in critically ill patients. TPE may be beneficial in patients at high risk for bleeding complications and impaired liver synthesis and hemodynamics, while CytoSorb and MARS may be considered for patients in whom the elimination of smaller toxic compounds is a primary objective.

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

Background

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

Methods

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

Results

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

Conclusion

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

Systematic review registration

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

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.

Artificial liver support in patients with liver failure: a modified DELPHI consensus of international experts

The present narrative review on albumin dialysis provides evidence-based and expert opinion guidelines for clinicians caring for adult patients with different types of liver failure. The review was prepared by an expert panel of 13 members with liver and ntensive care expertise in extracorporeal liver support therapies for the management of patients with liver failure. The coordinating committee developed the questions according to their importance in the management of patients with liver failure. For each indication, experts conducted a comprehensive review of the literature aiming to identify the best available evidence and assessed the quality of evidence based on the literature and their experience. Summary statements and expert's recommendations covered all indications of albumin dialysis therapy in patients with liver failure, timing and intensity of treatment, efficacy, technical issues related to the device and safety. The panel supports the data from the literature that albumin dialysis showed a beneficial effect on hepatic encephalopathy, refractory pruritus, renal function, reduction of cholestasis and jaundice. However, the trials lacked to show a clear beneficial effect on overall survival. A short-term survival benefit at 15 and 21 days respectively in acute and acute-on-chronic liver failure has been reported in recent studies. The technique should be limited to patients with a transplant project, to centers experienced in the management of advanced liver disease. The use of extracorporeal albumin dialysis could be beneficial in selected patients with advanced liver diseases listed for transplant or with a transplant project. Waiting future large randomized controlled trials, this panel experts' statements may help careful patient selection and better treatment modalities.

Apixaban in patients on haemodialysis: a single-dose pharmacokinetics study

BACKGROUND

Apixaban, a direct oral anticoagulant inhibiting factor Xa, has been proven to reduce the risk of atrial fibrillation-related stroke and thromboembolism in patients with mild to moderate renal insufficiency. Patients on renal replacement therapy, however, were excluded from randomized controlled trials. Therefore, uncertainty remains concerning benefits, dosing and timing of intake in haemodialysis population.

METHODS

We conducted a Phase II pharmacokinetics study in which 24 patients on maintenance haemodialysis were given a single dose (2.5 mg or 5 mg) of apixaban, either 30 min before or immediately after dialysis on the mid-week dialysis day.

RESULTS

Apixaban 5 mg resulted in higher area under the curve (AUC0-48) in comparison with 2.5 mg, although significance could only be reached for dosing pre-dialysis (2.5 mg versus 5 mg, P = 0.008). In line, peak concentrations (Cmax) after dosing pre-dialysis were significantly higher in the 5 mg than in the 2.5 mg groups (P = 0.02). In addition, dialysis resulted in significant reduction of drug exposure. AUC0-48 pre-dialysis were on average 48% (2.5 mg) and 26% (5 mg) lower than the AUC0-48 post-dialysis, in line with Cmax. As a result, a dose of 2.5 mg post-dialysis and a dose of 5 mg pre-dialysis resulted in similar AUC0-48. In contrast, significant differences were found between the 5 mg group post-dialysis and the 2.5 mg group pre-dialysis (P = 0.02).

CONCLUSIONS

Our data suggest that exposure to apixaban in patients on maintenance haemodialysis is dependent not only on drug dose but also on timing of intake relative to the haemodialysis procedure.

MARS: Should I Use It?

Severe liver failure, including acute liver failure and acute-on-chronic liver failure, is associated with high mortality, and many patients die despite aggressive medical therapy. While liver transplantation is a viable treatment option for liver failure patients, a large proportion of these patients die given the shortage in the liver donation and the severity of illness, leading to death while waiting for a liver transplant. Extracorporeal liver support devices, including molecular adsorbent recirculating system (MARS), have been developed as bridge to transplantation (bridge for patients who are decompensating while waiting for liver transplantation) and bridge to recovery (for whom recovery is deemed reasonable). In addition to its uses in acute liver failure and acute-on-chronic liver failure, the MARS system has also been applied in various clinical settings, such as drug overdosing and poisoning and intractable cholestatic pruritus refractory to pharmacological treatment. This review aims to discuss the controversies, potential benefits, practicalities, and disadvantages of using MARS in clinical practice.

A novel predictive score for citrate accumulation among patients receiving artificial liver support system therapy with regional citrate anticoagulation

Patients with liver failure may suffer citrate accumulation when using regional citrate anticoagulation for artificial liver support system therapy (RCA-ALSS therapy). This study aimed to develop a predictive scoring system to stratify the risk of citrate accumulation. A total of 338 patients treated with RCA-ALSS therapy were retrospectively enrolled and randomly divided into derivation and validation cohorts. Longer duration of citrate accumulation (LDCA) was defined as the presence of citrate accumulation 2 h after RCA-ALSS therapy. Four baseline variables were found to be independently associated with LDCA: gender, international normalized ratio of prothrombin time, serum creatinine, and serum chloride. A predictive R-CA model and its simplified R-CA score were developed. The R-CA model (AUROC = 0.848) was found to be superior to the MELD score (AUROC = 0.725; p = 0.022) and other univariate predictors (AUROCs < 0.700; all p ≤ 0.001) in predicting LDCA. The R-CA score (AUROC = 0.803) was as capable as the R-CA model (p = 0.369) and the MELD score (p = 0.174), and was superior to other univariate predictors (all p < 0.05) in predicting LDCA. An R-CA score of 0–2 had a negative predictive value of 90.2% for LDCA. Our R-CA score reliably predicts LDCA in patients with RCA-ALSS therapy, and it is easy to use. Patients with R-CA score of 0–2 can safely receive RCA-ALSS therapy, while others should be carefully evaluated before treatment.

Trial registration: Chinese Clinical Trial Registry, ChiCTR2000029179. Registered 17 January 2020, https://www.chictr.org.cn/showproj.aspx?proj=48084.

Artificial liver support systems: what is new over the last decade?

The liver is a complex organ that performs vital functions of synthesis, heat production, detoxification and regulation; its failure carries a highly critical risk. At the end of the last century, some artificial liver devices began to develop with the aim of being used as supportive therapy until liver transplantation (bridge-to-transplant) or liver regeneration (bridge-to-recovery). The well-recognized devices are the Molecular Adsorbent Recirculating System™ (MARS™), the Single-Pass Albumin Dialysis system and the Fractionated Plasma Separation and Adsorption system (Prometheus™). In the following years, experimental works and early clinical applications were reported, and to date, many thousands of patients have already been treated with these devices. The ability of artificial liver support systems to replace the liver detoxification function, at least partially, has been proven, and the correction of various biochemical parameters has been demonstrated. However, the complex tasks of regulation and synthesis must be addressed through the use of bioartificial systems, which still face several developmental problems and very high production costs. Moreover, clinical data on improved survival are conflicting. This paper reviews the progress achieved and new data published on artificial liver support systems over the past decade and the prospects for these devices.

[Regional citrate anticoagulation in renal replacement therapy in the intensive care station : Recommendations from the renal section of the DGIIN, ÖGIAIN and DIVI]

BACKGROUND

Regional citrate anticoagulation (RCA) in continuous renal replacement therapy can effectively anticoagulate dialysis circuits without having adverse effects on systemic heparin application. In particular, in continuous renal replacement therapy RCA is well established and represents a safe procedure with longer filter lifetimes and fewer bleeding complications.

OBJECTIVES

To provide guidance on the indications, advantages and disadvantages, and use of RCA, current recommendations from the renal section of the DGIIN (Deutschen Gesellschaft für Internistische Intensivmedizin und Notfallmedizin), ÖGIAIN (Österreichischen Gesellschaft für Internistische und Allgemeine Intensivmedizin und Notfallmedizin) and DIVI (Deutschen Interdisziplinären Vereinigung für Intensiv- und Notfallmedizin) are stated.

MATERIALS AND METHODS

The recommendations in this paper are based on the current KDIGO (Kidney Disease: Improving Global Outcomes) guidelines, other published guidelines and protocols as well as the expert knowledge and clinical experience of the authors.

RESULTS

The use of commercially available machines with coupled pumps and integrated safety features, effective personal training and standardized protocols for clinical usage (SOP) is particularly important for the safe clinical use of RCA in renal replacement therapy. Contrary to previous recommendations, even liver failure or shock with lactic acidosis may no longer be an absolute contra-indication for RCA. However, these particular patients have to be carefully monitored for signs of citrate accumulation.

Good Tolerance of Citrate Accumulation due to Plasma Exchange among Patients with Acute-on-Chronic Liver Failure: A Prospective, Observational Study

Aim

To assess the tolerance of citrate accumulation due to plasma exchange (PE) among patients with acute-on-chronic liver failure (ACLF).

Methods

A prospective, observational study was conducted among patients with ACLF who received heparin anticoagulation during PE-centered therapy without filtration and dialysis. Citrate accumulation was defined as the value of total calcium (Catot) to ionized calcium (Caion) ratio (Catot/Caion) greater than or equal to 2.5 (Catot/Caion ≥ 2.5).

Results

Fifty-four patients were enrolled. The mean age and MELD score were 50.0 ± 11.3 years old and 25 ± 7, respectively. Thirty-three patients had liver cirrhosis. The total 3-month survival rate was 57.4% (31/54). The mean Catot/Caion at the time before PE was 2.05 ± 0.14. Catot/Caion ≥ 2.5 occurred in 100.0% (54/54) and 29.6% (16/54) of patients with mean Catot/Caion of 4.34 ± 1.52 and 2.36 ± 0.32 immediately after PE and 1 hour after PE, respectively, and these levels were much higher than those before PE (p < 0.01). However, all values returned to lower than 2.5 by the next morning with no difference from those before PE (2.10 ± 0.14 versus 2.05 ± 0.14, p > 0.05). Hypocalcemia (ionized calcium) and mild alkalosis were the main metabolic alterations. No symptoms associated with hypocalcemia occurred.

Conclusions

Citrate accumulation is well tolerated by patients with ACLF who receive PE-centered therapy without filtration and dialysis. This study is regeristed with ChiCTR-OOC-17013618.

The molecular adsorbent recirculating system in posthepatectomy liver failure: Results from a prospective phase I study

Posthepatectomy liver failure (PHLF) represents the single most important cause of postoperative mortality after major liver resection, yet no effective treatment option is available. Extracorporeal liver support devices might be helpful, but systematic studies are lacking. Accordingly, we aimed to assess the safety and feasibility of the Molecular Adsorbent Recirculating System (MARS) in patients with PHLF. Between December 2012 and May 2015, a total of 206 patients underwent major or extended hepatectomy, and 10 consecutive patients with PHLF (according to the Balzan 50:50 criteria) were enrolled into the study. MARS treatment was initiated on postoperative day 5-7, and five to seven consecutive treatment sessions were completed for each patient. In total, 59 MARS cycles were implemented, and MARS was initiated and completed without major complications in any patient. However, 1 patient developed an immense asymptomatic hyperbilirubinemia (without encephalopathy), 1 had repeated clotting problems in the MARS filter, and 2 patients experienced access problems with the central venous line. Otherwise, no adverse events were observed. In 9 patients, the bilirubin level and international normalized ratio decreased significantly (P < 0.05) during MARS treatment. The 60- and 90-day mortality was 0% and 10%, respectively. Among the 9 survivors, 4 still had liver dysfunction at 90 days postoperatively. Five patients were alive 1 year postoperatively without any signs of liver dysfunction or disease recurrence. Conclusion: The use of MARS in PHLF is feasible and safe and improves liver function in patients with PHLF. In the present study, 60- and 90-day mortality rates were unexpectedly low compared to a historical control group. The impact of MARS treatment on mortality in PHLF should be further evaluated in a randomized controlled clinical trial. (Hepatology Communications 2018;2:445-454).

Therapeutic plasma exchange: A prospective randomized trial to evaluate 2 strategies in patients with liver failure

OBJECTIVE

To compare two means of performing therapeutic plasma exchange (TPE) in patients with liver failure.

METHOD

This open-label monocentric randomized trial, conducted in a single prestigious general healthcare facility, recruited liver failure patients with an indication to receive artificial liver support therapy for TPE. All patients underwent TPE procedures and were administered in a random sequence: heparin-free or systemic heparinization with unfractionated heparin. The primary endpoint was completion of TPE sessions, and the secondary endpoints included the safety and efficacy.

RESULTS

In the period of the studying, there were 164 patients being recruited in and underwent total of 398 randomized TPEs: 168 with unfractionated heparin and 230 with heparin-free. In unfractionated heparin group, there were 3 cases (1.79%) being interrupted due to uncontrollable intraoperative pulmonary hemorrhages and gastrointestinal bleeding. In heparin-free group, 228 (99.13%) were completed successfully and 2 of them (0.87%) were switched from heparin-free to unfractionated heparin eventually. No significant differences were found between the two groups for either RRs or IRs (P > 0.05).

CONCLUSION

Heparin-free regimen is feasible and safer than systemic heparinization with unfractionated heparin in the process of TPEs in patients with liver failure.

Application of regional citrate anticoagulation during plasma adsorption and plasma exchange for patients with liver failure at high risk of bleeding

AIM

To analyze the feasibility and safety of regional citrate anticoagulation (RCA) during plasma adsorption (PA) plus plasma exchange (PE) therapy for patients with liver failure at high risk of bleeding.

METHODS

This was a retrospective study conducted at the Center of Infectious Diseases, West China Hospital of Sichuan University from October 2016 to July 2017. The clinical data of patients with liver failure at high risk of bleeding who received RCA during PA plus PE therapy were collected. The therapeutic effects, citrate accumulation, electrolytes, and acid-base changes were retrospectively analyzed. Citrate accumulation was defined as the total calcium (Ca_tot) to ionized calcium (Ca_ion) ratio (Ca_tot/Ca_ion) ≥ 2.5.

RESULTS

Of the seven patients included, two survived and five died. Twenty four sessions of RCA for PA plus PE therapy were accomplished. The mean Ca_ionin vitro during PA therapy was 0.28 mmol/L ± 0.09 mmol/L. Citrate accumulation occurred in 45.8% (11/24) of sessions during PA therapy and in all the sessions at the end of PE therapy. Although citrate accumulation still occurred in 41.7% (10/24) of sessions 2 h after PE therapy, it had been decreased obviously when compared with that at the end of PE therapy (P < 0.01) and it was not present by the next morning. No new bleeding occurred and the original bleeding did not deteriorate during and after PA plus PE therapy. The main side effects were alkalosis and transient low level of Ca_ion and high level of Ca_tot.

CONCLUSION

Patients with liver failure still have certain ability to metabolize citrate and tolerate citrate accumulation. RCA may be feasible and safe in the PA plus PE therapy for patients with liver failure.

Long-term continuous renal replacement therapy and anticoagulation with citrate in critically ill patients with severe liver dysfunction

Background

As of 2009, anticoagulation with citrate was standard practice in continuous renal replacement therapy (CRRT) for critically ill patients at the University Medical Centre of Saarland, Germany. Partial hepatic metabolism of citrate means accumulation may occur during CRRT in critically ill patients with impaired liver function. The aim of this study was to evaluate the actual influence of hepatic function on citrate-associated complications during long-term CRRT.

Methods

In a retrospective study conducted between January 2009 and November 2012, all cases of dialysis therapy performed in the interdisciplinary surgical intensive care unit were analysed. Inclusion criteria were CRRT and regional anticoagulation with citrate, pronounced liver dysfunction, and pathologically reduced indocyanine green plasma disappearance rate (ICG-PDR).

Results

A total of 1339 CRRTs were performed in 69 critically ill patients with liver failure. At admission, the mean Model for End-stage Liver Disease score was 19.2, and the mean ICG-PDR was 9.8%. Eight patients were treated with liver replacement therapy, and 30 underwent transplants. The mortality rate was 40%. The mean duration of dialysis was 19.4 days, and the circuit patency was 62.2 h. Accumulation of citrate was detected indirectly by total serum calcium/ionised serum calcium (tCa/iCa) ratio > 2.4. This was noted in 16 patients (23.2%). Dialysis had not to be discontinued for metabolic disorder or accumulation of citrate in any case. In 26% of cases, metabolic alkalosis occurred with pH > 7.5. Interestingly, no correlation between citrate accumulation and liver function parameters was detected. Moreover, most standard laboratory liver function parameters showed poor predictive capabilities for accumulation of citrate.

Conclusions

Our findings indicate that extra-hepatic metabolism of citrate seems to exist, avoiding in most cases citrate accumulation in critically ill patients despite impaired liver function. Because the citric acid cycle is oxygen-dependent, disturbed microcirculation would result in inadequate citrate metabolism. Raising the tCa/iCa ratio would therefore be an indicator of severity of illness and mortality rather than of liver failure. However, further studies are warranted for confirmation.

Current Evidence for Extracorporeal Liver Support Systems in Acute Liver Failure and Acute-on-Chronic Liver Failure

Artificial (nonbiological) extracorporeal liver support devices aim to remove albumin-bound and water-soluble toxins to restore and preserve hepatic function and mitigate or limit the progression of multiorgan failure while hepatic recovery or liver transplant occurs. The following beneficial effects have been documented: improvement of jaundice, amelioration of hemodynamic instability, reduction of portal hypertension, and improvement of hepatic encephalopathy. The only randomized prospective multicenter controlled trial to show an improvement in transplant-free survival was for high-volume plasmapheresis. Biological (cell-based) extracorporeal liver support systems aim to support the failing liver through detoxification and synthetic function and warrant further study for safety and benefit.

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

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

Non-bioartificial liver support system for treating patients with severe hepatitis: Common problems and nursing countermeasures

Non-bioartificial liver support system, a common and effective therapy to salvage patients with severe hepatitis and a temporary substitution of the liver function, may "bridge" patients to liver transplantation or recovery. However, nurses play a pivotal role in the process of non-bioartificial liver support system, so it is key for successful treatment that they are able to timely identify and effectively manage adverse reactions during the process. Given all this, this review discusses common problems and nursing countermeasures encountered during treatment with the non-bioartificial liver support system in patients with severe hepatitis, aiming at improving their capacity of detecting and dealing with adverse reactions, and thus increasing the efficacy.

Heparin-coated dialyzer membranes: is non-inferiority good enough?

Evidence on the optimal anticoagulation regimen for hemodialysis in patients at high bleeding risk is scarce. The HepZero study is the first large multinational study comparing two different anticoagulation strategies to avoid systemic heparinization. The use of a heparin-coated dialysis membrane proved to be non-inferior to saline infusion. Superiority of either treatment, however, could not be demonstrated. These findings challenge current guidelines but equally raise questions on the choice of either strategy as compared with regional citrate anticoagulation.

Dialysis-dependent acute kidney injury in children with end-stage liver disease: prevalence, dialysis modalities and outcome

BACKGROUND

Acute kidney injury (AKI) is a major complication in children with hepatic failure which leads to increased morbidity and mortality. The aim of this study was to provide paediatric data on the prevalence of dialysis-dependent AKI (dAKI), the feasibility and efficacy of dialysis methods and outcome.

METHODS

We conducted a retrospective analysis of 367 children listed for orthotopic liver transplantation (OLT) in our centre during the past decade.

RESULTS

Data on 30 children (15 boys, 15 girls) were compiled for retrospective analysis, and data on dialysis feasibility and efficacy were available for 26 of these. Median age was 3.5 (range 0.4-17.7) years. Median MELD (Model For End-Stage Liver Disease) score was 33. dAKI was caused by hepato-renal syndrome in 16 of the 30 children. Twenty-one patients were treated with continuous veno-venous haemofiltration (CVVH), and nine patients received peritoneal dialysis (PD). Overall mortality was 77%. Mortality within the PD-group was 100 % versus 67% in the CVVH-group (p = 0.039). Urea reduction rate within the first 24 h of treatment was 12.9% in the PD group and 23.5% in the CVVH group (p = 0.019).

CONCLUSIONS

Children with end-stage liver disease have a high risk for dAKI associated with high mortality. CVVH is associated with better efficacy and less mortality than PD.

Regional citrate anticoagulation for RRTs in critically ill patients with AKI

Hemorrhagic complications have been reported in up to 30% of critically ill patients with AKI undergoing RRT with systemic anticoagulation. Because bleeding is associated with significantly increased mortality risk, strategies aimed at reducing hemorrhagic complications while maintaining extracorporeal circulation should be implemented. Among the alternatives to systemic anticoagulation, regional citrate anticoagulation has been shown to prolong circuit life while reducing the incidence of hemorrhagic complications and lowering transfusion needs. For these reasons, the recently published Kidney Disease Improving Global Outcomes Clinical Practice Guidelines for Acute Kidney Injury have recommended regional citrate anticoagulation as the preferred anticoagulation modality for continuous RRT in critically ill patients in whom it is not contraindicated. However, the use of regional citrate anticoagulation is still limited because of concerns related to the risk of metabolic complications, the complexity of the proposed protocols, and the need for customized solutions. The introduction of simplified anticoagulation protocols based on citrate and the development of dialysis monitors with integrated infusion systems and dedicated software could lead to the wider use of regional citrate anticoagulation in upcoming years.

Year in review 2012: Critical Care--Cardiology

In this review I discuss key research papers in cardiology and intensive care published in Critical Care during 2012 with related studies published in other journals quoted whenever appropriate. These studies are grouped into the following categories: cardiovascular therapies, mechanical therapies, pathophysiologic mechanisms, hemodynamic monitoring, ultrasound in respiratory failure, microcirculation, and miscellaneous.

Extracorporeal liver support

PURPOSE OF REVIEW

The mortality in patients suffering from liver failure decreased in line with medical progress over the past decades. However, it still remains unacceptably high and liver transplantation still provides the only definite treatment for many patients. The goal of extracorporeal liver support systems is to improve the clinical condition of patients waiting for liver transplantation and/or enhance the regeneration of native injured liver. Nonbiological liver support systems with pure detoxification and biological liver support systems with assumed synthesis and metabolism in addition to detoxification are currently under clinical investigation. Since patient survival is the most significant outcome parameter, we focus in this review on prospective randomized trials with survival rate as primary outcome parameter.

RECENT FINDINGS

Although a short-term outcome benefit in patients with acute-on-chronic liver failure was shown in some of these trials, long-term outcome has not been improved significantly with either of the support systems. In spite of more favourable but yet limited data in patients with acute liver failure, it is too early to draw definite conclusions.

SUMMARY

The future development of liver support systems may provide different combinations of new adsorbents, integrated regional citrate anticoagulation and eventual substitution of irreversibly damaged albumin.

The role of molecular adsorbent recirculating system dialysis for extracorporeal liver support in children

The majority of children with acute, acute-on-chronic, and progressive chronic liver failure require liver transplantation. Since organ availability is limited, extracorporeal liver support systems are increasingly applied to bridge the time until transplantation. At present, four different devices are available: the molecular adsorbent recirculating system (MARS), Prometheus dialysis, plasma exchange combined with hemodialysis (PE/HD), and single-pass albumin dialysis (SPAD). Randomized trials in adults have demonstrated efficient toxin removal, improved portal hypertension, hemodynamic stability, and improved hepatic encephalopathy compared with standard medical therapy. None of the liver support systems has yet been evaluated systematically in children. Knowledge of the specific indications and technical features of the different devices is essential if applied in children. MARS combines albumin dialysis with conventional hemodialysis and allows for efficient removal of water and protein-bound toxins without exogenous protein delivery and the associated infectious and allergic risks. It has successfully been applied in children with otherwise intractable cholestatic pruritus and with liver failure. The benefits, however, need to be balanced against the costs and the risk of volume and nitrogen overload if repeated plasma infusion is required. In cases of active bleeding, plasma exchange in combination with hemodialysis should be preferred.

Efficacy and safety of a citrate-based protocol for sustained low-efficiency dialysis in AKI using standard dialysis equipment

BACKGROUND AND OBJECTIVES

A simple anticoagulation protocol was developed for sustained low-efficiency dialysis (SLED) in patients with AKI, based on the use of anticoagulant citrate dextrose solution formulation A (ACD-A) and standard dialysis equipment. Patients' blood recalcification was obtained from calcium backtransport from dialysis fluid.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

All patients treated with SLED (8- to 12-hour sessions) for AKI in four intensive care units of a university hospital were studied over a 30-month period, from May 1, 2008 to September 30, 2010. SLED interruptions and their causes, hemorrhagic complications, as well as coagulation parameters, ionized calcium, and blood citrate levels were recorded.

RESULTS

This study examined 807 SLED sessions in 116 patients (mean age of 69.7 years [SD 12.1]; mean Acute Physiology and Chronic Health Evaluation II score of 23.8 [4.6]). Major bleeding was observed in six patients (5.2% or 0.4 episodes/100 person-days follow-up while patients were on SLED treatment). Citrate accumulation never occurred, even in patients with liver dysfunction. Intravenous calcium for ionized hypocalcemia (< 3.6 mg/dl or < 0.9 mmol/L) was needed in 28 sessions (3.4%); in 8 of these 28 sessions (28.6%), low ionized calcium was already present before SLED start. In 92.6% of treatments, SLED was completed within the scheduled time (median 8 hours). Interruptions of SLED by impending/irreversible clotting were recorded in 19 sessions (2.4%). Blood return was complete in 98% of the cases. In-hospital mortality was 45 of 116 patients (38.8%).

CONCLUSIONS

This study protocol affords efficacious and safe anticoagulation of the SLED circuit, avoiding citrate accumulation and, in most patients, systematic calcium supplementation; it can be implemented with commercial citrate solutions, standard dialysis equipment, on-line produced dialysis fluid, and minimal laboratory monitoring.

Extracorporeal detoxification for hepatic failure using molecular adsorbent recirculating system: depurative efficiency and clinical results in a long-term follow-up

Acute liver failure and acute-on-chronic liver failure still show a poor prognosis. The molecular adsorbent recirculating system (MARS) has been extensively used as the most promising detoxifying therapy for patients with these conditions. Sixty-four patients with life-threatening liver failure were selected, and 269 MARS treatments were carried out as a bridge for orthotopic liver transplantation (OLT) or for liver function recovery. All patients were grouped according to the aim of MARS therapy. Group A consisted of 47 patients treated for liver function recovery (median age 59 years, range 23-82). Group B consisted of 11 patients on the waiting list who underwent OLT (median age 47 years, range 32-62). Group C consisted of 6 patients on the waiting list who did not undergo OLT (median age 45.5 years, range 36-54, P = 0.001). MARS depurative efficiency in terms of liver toxins, cytokines, and growth factors was assessed together with the clinical outcome of the patients during a 1-year follow-up. Total bilirubin reduction rate per session (RRs) for each MARS session was 23% (range 17-29); direct bilirubin RRs was 28% (21-35), and indirect bilirubin RRs was 8% (3-21). Ammonia RRs was 34% (12-86). Conjugated cholic acid RRs was 58% (48-61); chenodeoxycholic acid RRs was 34% (18-48). No differences were found between groups. Hepatocyte growth factor (HGF) values on starting MARS were 4.1 ng/mL (1.9-7.9) versus 7.9 ng/mL (3.2-14.1) at MARS end (P < 0.01). Cox regression analysis to determine the risk factors predicting patient outcomes showed that age, male gender, and Sequential Organ Failure Assessment score (but not Model for End-stage Liver Disease score) were factors predicting death, whereas the number of MARS sessions and the ΔHGF proved protective factors. Kaplan-Meier survival analysis was also used; after 12 months, 21.3% of patients in Group A survived, while 90.9% were alive in Group B and 16.7% in Group C (log rank = 0.002). In conclusion, MARS was clinically well tolerated by all patients and significantly reduced hepatic toxins. Better survival rates were linked to an OLT program, but patients' clinical characteristics on starting MARS therapy were the main factors predicting survival. The role of HGF should be evaluated in larger clinical trials.

Bench-to-bedside review: Citrate for continuous renal replacement therapy, from science to practice

To prevent clotting in the extracorporeal circuit during continuous renal replacement therapy (CRRT) anticoagulation is required. Heparin is still the most commonly used anticoagulant. However, heparins increase the risk of bleeding, especially in critically ill patients. Evidence has accumulated that regional anticoagulation of the CRRT circuit with citrate is feasible and safe. Compared to heparin, citrate anticoagulation reduces the risk of bleeding and requirement for blood products, not only in patients with coagulopathy, but also in those without. Metabolic complications are largely prevented by the use of a strict protocol, comprehensive training and integrated citrate software. Recent studies indicate that citrate can even be used in patients with significant liver disease provided that monitoring is intensified and the dose is carefully adjusted. Since the citric acid cycle is oxygen dependent, patients at greatest risk of accumulation seem to be those with persistent lactic acidosis due to poor tissue perfusion. The use of citrate may also be associated with less inflammation due to hypocalcemia-induced suppression of intracellular signaling at the membrane and avoidance of heparin, which may have proinflammatory properties. Whether these beneficial effects increase patient survival needs to be confirmed. However, other benefits are the reason that citrate should become the first choice anticoagulant for CRRT provided that its safe use can be guaranteed.

Regional citrate anticoagulation in patients with liver failure--time for a rethink?

Regional citrate anticoagulation (RCA) for continuous renal replacement therapy (CRRT) has become increasingly attractive in recent years due to its favourable low bleeding risk profile. Its use in liver failure, however, has been limited due to the risk of citrate accumulation and toxicity. In the previous issue of Critical Care, Schultheiss and colleagues look at CRRT using RCA in liver failure patients. They demonstrate that citrate accumulation can be predicted using the total calcium (Ca_tot) to ionised calcium (Ca_ion) ratio (Ca_tot/Ca_ion), and determine that despite the occurrence of significant citrate accumulation, the effects of citrate accumulation are not as severe as might have been expected. This study raises interesting prospects with regard to RCA use in liver failure, and we postulate that citrate may have a role as a prognostic marker of metabolic capacity much as in the way of lactate and methacetin. However, further studies are warranted, in particular examining its application in subgroups of liver failure (chronic, acute, hyperacute and subacute), before its use becomes commonplace.