The persistent potential of extracorporeal therapies in liver failure

Update on the management of acute liver failure

PURPOSE OF REVIEW

Acute liver failure (ALF) is a rare, life-threatening but potentially reversible clinical syndrome characterized by multiple organ failure secondary to the rapid loss of liver function. Key management challenges include severe cerebral oedema and complex treatments to support multiple organ failure. This review focuses on the fundamental principles of management and recent treatment advances.

RECENT FINDINGS

Identifying the cause of ALF is key to guiding specific therapies. The early commencement of continuous renal replacement therapy (CRRT) to control hyperammonaemia can now be considered an important standard of care, and plasma exchange may have a role in the sickest of ALF patients; however, other blood purification modalities still lack supporting evidence. Close monitoring, regular investigations, careful attention to neuroprotective measures, as well as optimizing general physiological supports is essential. Where possible, patients should be transferred to a liver transplant centre to achieve the best chance of transplant-free survival, or to undergo emergency liver transplantation if required.

SUMMARY

This review outlines current principles of ALF management, emerging treatment strategies, and a practical approach to management in the ICU. These recommendations can form the development of local guidelines, incorporating current best evidence for managing this rare but often lethal condition.

Outcome of patients with different stages of acute-on-chronic liver failure treated with artificial liver support system

Background

Elevated international normalized ratio of prothrombin time (PT-INR) is one of the key characteristics of acute-on-chronic liver failure (ACLF). Whether the staging of PT-INR has the ability to screen out subgroups of ACLF patients who would be more eligible for artificial liver support system (ALSS) treatment has not been studied in detail.

Methods

A previous study enrolled patients receiving ALSS treatment with regional citrate anticoagulation from January 2018 to December 2019. Patients with different PT-INR intervals were retrospectively enrolled: 1.3 ≤ PT-INR < 1.5 (Pre-stage), 1.5 ≤ PT-INR < 2.0 (Early-stage), 2.0 ≤ PT-INR < 2.5 (Mid-stage), and PT-INR ≥ 2.5 (End-stage). The Cox proportional hazards models were used to estimate the association between stages of ACLF or sessions of ALSS treatment and 90 day mortality.

Results

A total of 301 ACLF patients were enrolled. The 90 day mortality risk of Early-stage ACLF patients (adjusted hazard ratio (aHR) (95% confidence interval (CI)), 3.20 (1.15-8.89), p = 0.026), Mid-stage ACLF patients (3.68 (1.34-10.12), p = 0.011), and End-stage ACLF patients (12.74 (4.52-35.91), p < 0.001) were higher than that of Pre-stage ACLF patients, respectively. The 90 day mortality risk of Mid-stage ACLF patients was similar to that of Early-stage ACLF patients (1.15 (0.69-1.94), p = 0.591). The sessions of ALSS treatment was an independent protective factor (aHR (95% CI), 0.81 (0.73-0.90), p < 0.001). The 90 day mortality risk in ACLF patients received 3-5 sessions of ALSS treatment was lower than that of patients received 1-2 sessions (aHR (95% CI), 0.34 (0.20-0.60), p < 0.001), whereas the risk in patients received ≥6 sessions of ALSS treatment was similar to that of patients received 3-5 sessions (0.69 (0.43-1.11), p = 0.128).

Conclusion

ACLF patients in Pre-, Early-, and Mid-stages might be more eligible for ALSS treatment. Application of 3-5 sessions of ALSS treatment might be reasonable.

A breakthrough trial of an artificial liver without systemic heparinization in hyperbilirubinemia beagle models

The development of wearable artificial livers was restricted to device miniaturization and bleeding risk with water-soluble anticoagulants. Herein, a double-deck column filled with solid anticoagulant microspheres and Kevlar porous microspheres (KPMs, bilirubin adsorbents) was connected with the principle machine of wearable artificial liver (approximately 9 kg) to treat hyperbilirubinemia beagles for the first time. With the initial normal dose of heparin, the double-deck column could afford 3 h hemoperfusion in whole blood without thrombus formation. The removal efficiency of the double-deck column for total bilirubin (TBIL) was 31.4%. Interestingly, the excessive amounts of hepatocyte metabolites were also decreased by approximately 25%. The "anticoagulant + column" realized safe and effective whole blood hemoperfusion without the plasma separation system and heparin pump; however, the proposed principle machine of wearable artificial liver and "anticoagulant + column" cannot completely replace the bio-liver now. The intelligence of the device and the versatility of the adsorbent need to be improved; moreover, advanced experimental techniques need to be developed to validate the survival rates in animals. Overall, this study is a meaningful trial for the development of wearable artificial livers in the future.

Voriconazole Pharmacokinetics Are Not Altered in Critically Ill Patients with Acute-on-Chronic Liver Failure and Continuous Renal Replacement Therapy: An Observational Study

Infection and sepsis are a main cause of acute-on-chronic liver failure (ACLF). Besides bacteria, molds play a role. Voriconazole (VRC) is recommended but its pharmacokinetics (PK) may be altered by ACLF. Because ACLF patients often suffer from concomitant acute renal failure, we studied the PK of VRC in patients receiving continuous renal replacement therapy (RRT) with ACLF and compared it to PK of VRC in critically ill patients with RRT without concomitant liver failure (NLF). In this prospective cohort study, patients received weight-based VRC. Pre- and post-dialysis membrane, and dialysate samples obtained at different time points were analyzed by high-performance liquid chromatography. An integrated dialysis pharmacometric model was used to model the available PK data. The recommended, 50% lower, and 50% higher doses were analyzed by Monte-Carlo simulation (MCS) for day 1 and at steady-state with a target trough concentration (TC) of 0.5–3mg/L. Fifteen patients were included in this study. Of these, 6 patients suffered from ACLF. A two-compartment model with linear clearance described VRC PK. No difference for central (V1) or peripheral (V2) volumes of distribution or clearance could be demonstrated between the groups. V1 was 80.6L (95% confidence interval: 62.6–104) and V2 106L (65–166) with a body clearance of 4.7L/h (2.87–7.81) and RRT clearance of 1.46L/h (1.29–1.64). MCS showed TC below/within/above target of 10/74/16% on day 1 and 9/39/52% at steady-state for the recommended dose. A 50% lower dose resulted in 26/72/1% (day 1) and 17/64/19% at steady-state and 7/57/37% and 7/27/67% for a 50% higher dose. VRC pharmacokinetics are not significantly influenced by ACLF in critically ill patients who receive RRT. Maintenance dose should be adjusted in both groups. Due to the high interindividual variability, therapeutic drug monitoring seems inevitable.