Evaluation of an ADVanced Organ Support (ADVOS) system in a two-hit porcine model of liver failure plus endotoxemia

The role of the ADVanced Organ Support (ADVOS) system in critically ill patients with multiple organ failure

Background

Multi‐organ failure characterized by acute kidney injury, liver dysfunction, and respiratory failure is a complex condition associated with high mortality, for which multiple individual support devices may be simultaneously required. This review aims to appraise the current evidence for the ADVanced Organ Support (ADVOS) system, a novel device integrating liver, lung, and kidney support with blood detoxification.

Methods

We performed a literature review of the PubMed database to identify human and animal studies evaluating the ADVOS system.

Results

In porcine models of acute liver injury and small clinical studies in humans, ADVOS significantly enhanced the elimination of water‐soluble and protein‐bound toxins and metabolites, including creatinine, ammonia, blood urea nitrogen, and lactate. Cardiovascular parameters (mean arterial pressure, cerebral perfusion pressure, and cardiac index) and renal function were improved. ADVOS clears carbon dioxide (CO₂) effectively with rapid correction of pH abnormalities, achieving normalization of CO₂, and bicarbonate levels. In patients with COVID‐19 infection, ADVOS enables rapid correction of acid–base disturbance and respiratory acidosis. ADVOS therapy reduces mortality in multi‐organ failure and has been shown to be safe with minimal adverse events.

Conclusions

From the small observational studies analyzed, ADVOS demonstrates excellent detoxification of water‐soluble and protein‐bound substances. In particular, ADVOS permits the correction of metabolic and respiratory acidosis through the fluid‐based direct removal of acid and CO₂. ADVOS is associated with significant improvements in hemodynamic and biochemical parameters, a trend toward improved survival in multi‐organ failure, and is well‐tolerated. Larger randomized trials are now necessary to further validate these encouraging results.

Registry on extracorporeal multiple organ support with the advanced organ support (ADVOS) system: 2-year interim analysis

The objective of this registry is to collect data on real-life treatment conditions for patients for whom multiple organ dialysis with Advanced Organ Support (ADVOS) albumin hemodialysis is indicated.This registry was performed under routine conditions and without any study-specific intervention, diagnostic procedures, or assessments. Data on clinical laboratory tests, health status, liver function, vital signs, and examinations were collected (DRKS-ID: DRKS00017068). Mortality rates 28 and 90 days after the first ADVOS treatment, adverse events and ADVOS treatment parameters, including treatment abortions, were documented.This analysis was performed 2 years after the first patient was included on January 18, 2017. As of February 20, 2019, 4 clinical sites in Germany participated and enrolled 118 patients with a median age of 60 (IQR: 45, 69) of whom 70 were male (59.3%). Patients had a median SOFA Score of 14 (IQR: 11, 16) and a predicted mortality of 80%. The median number of failing organs was 3 (IQR: 2, 4).Four hundred twenty nine ADVOS treatments sessions were performed with a median duration of 17 hours (IQR: 6, 23). A 5.8% of the ADVOS sessions (25 of 429) were aborted due to device related errors, while 14.5% (62 of 429) were stopped for other reasons. Seventy nine adverse events were documented, 13 of them device related (all clotting, and all recovered without sequels).A significant reduction in serum creatinine (1.5 vs 1.2 mg/dl), blood urea nitrogen (24 vs 17 mg/dl) and bilirubin (6.9 vs 6.5 mg/dl) was observed following the first ADVOS treatment session. Blood pH, bicarbonate (HCO3-) and base excess returned to the physiological range, while partial pressure of carbon dioxide (pCO2) remained unchanged. At the time of the analysis, 28- and 90-day mortality were 60% and 65%, respectively, compared to an expected ICU-mortality rate of 80%. SOFA score was an independent predictor for outcome in a multivariable logistic regression analysis.The reported data show a high quality and completion of all participating centers. Data interpretation must be cautious due to the small number of patients, and the nature of the registry, without a control group. However, the data presented here show an improvement of expected mortality rates. Minor clotting events similar to other dialysis therapies occurred during the treatments.

pH-Dependent Protein Binding Properties of Uremic Toxins In Vitro

Protein-bound uremic toxins (PBUTs) are difficult to remove using conventional dialysis treatment owing to their high protein-binding affinity. As pH changes the conformation of proteins, it may be associated with the binding of uremic toxins. Albumin conformation at pH 2 to 13 was analyzed using circular dichroism. The protein binding behavior between indoxyl sulfate (IS) and albumin was examined using isothermal titration calorimetry. Albumin with IS, and serum with IS, p-cresyl sulfate, indole acetic acid or phenyl sulfate, as well as serum from hemodialysis patients, were adjusted pH of 3 to 11, and the concentration of the free PBUTs was measured using mass spectrometry. Albumin was unfolded at pH < 4 or >12, and weakened interaction with IS occurred at pH < 5 or >10. The concentration of free IS in the albumin solution was increased at pH 4.0 and pH 11.0. Addition of human serum to each toxin resulted in increased free forms at acidic and alkaline pH. The pH values of serums from patients undergoing hemodialysis adjusted to 3.4 and 11.3 resulted in increased concentrations of the free forms of PBUTs. In conclusion, acidic and alkaline pH conditions changed the albumin conformation and weakened the protein binding property of PBUTs in vitro.

Advanced organ support (ADVOS) in the critically ill: first clinical experience in patients with multiple organ failure

Background

Prevalence of multiple organ failure (MOF) in critically ill patients is increasing and associated mortality remains high. Extracorporeal organ support is a cornerstone in the management of MOF. We report data of an advanced hemodialysis system based on albumin dialysis (ADVOS multi device) that can regulate acid–base balance in addition to the established properties of renal replacement therapy and albumin dialysis systems in critically ill patients with MOF.

Methods

34 critically ill patients with MOF received 102 ADVOS treatment sessions in the Department of Intensive Care Medicine of the University Medical Center Hamburg-Eppendorf. Markers of metabolic detoxification and acid–base regulation were collected and blood gas analyses were performed. A subgroup analyses were performed in patients with severe acidemia (pH < 7.2).

Results

Median number of treatment sessions was 2 (range 1–9) per patient. Median duration of treatment was 17.5 (IQR 11–23) hours per session. Treatment with the ADVOS multi-albumin dialysis device caused a significant decrease in bilirubin levels, serum creatinine, BUN and ammonia levels. The relative elimination rate of bilirubin was concentration dependent. Furthermore, a significant improvement in blood pH, HCO₃⁻ and PaCO₂, was achieved during ADVOS treatment including six patients that suffered from severe metabolic acidosis refractory to continuous renal replacement therapy. Delta pH, HCO₃⁻ and PaCO₂ were significantly affected by the ADVOS blood flow rate and pH settings. This improvement in the clinical course during ADVOS treatments allowed a reduction in norepinephrine during ADVOS therapy. Treatments were well tolerated. Mortality rates were 50% and 62% for 28 and 90 days, respectively.

Conclusions

In this case series in patients with MOF, ADVOS was able to eliminate water-soluble and albumin-bound substances. Furthermore, the device corrected severe metabolic and respiratory acid–base disequilibrium. No major adverse events associated with the ADVOS treatments were observed.

Comparison of albumin dialysis devices molecular adsorbent recirculating system and ADVanced Organ Support system in critically ill patients with liver failure-A retrospective analysis

Extracorporeal albumin dialysis (ECAD) represents a supplemental therapy for patients with liver failure. Most experience was gained with the molecular adsorbent recirculating system (MARS). However, the ADVanced Organ Support (ADVOS) system was recently introduced. This study aims to compare effects of MARS and ADVOS on biochemical and clinical parameters in critically ill patients with liver failure using a retrospective analysis of ECAD at Jena University Hospital. Laboratory parameters, health scoring values, and need for transfusion were recorded before and after treatment. Generalized estimating equations were used to account for repeated measurements of multiple ECAD cycles per patient. Between 2012 and 2017, n = 75 MARS and n = 58 ADVOS cycles were evaluated. Although ADVOS runs significantly longer, both devices provided comparable reduction rates of bilirubin (MARS: -48 [-80.5 to -18.5] μmol/L vs ADVOS: -35 [-87.8 to -2.0] μmol/L, P = .194), a surrogate for detoxification capacity, while urea and lactate levels were more significantly lowered by the ADVOS system. In cycles with similar treatment times, both systems provided comparable reduction rates for bilirubin, renal replacement, coagulation, and metabolic parameters. Citrate was the preferred anticoagulant in case of bleeding. Neither bleeding tendency nor fibrinogen levels or platelets were altered by the type of anticoagulation. No adverse events were reported, but two sessions (one MARS and one ADVOS) were terminated early due to filter clotting. Experience is needed in the application of ADVOS and more prospective trials comparing the detoxification capacity of ECAD devices are needed to support and enlarge the findings of the current evaluation.

Options in extracorporeal support of multiple organ failure

Multiorgan failure is among the most frequent reasons of death in critically ill patients. Based on extensive and long-term use of renal replacement therapy, extracorporeal organ support became available for other organ failures. Initially, most of these techniques (e.g. extracorporeal membrane oxygenation, extracorporeal CO₂ removal [ECCO2R] and extracorporeal liver support) were used as stand-alone single organ support systems. Considering multiple interactions between native organs (“crosstalk”), combined or integrated extracorporeal organ support (ECOS) devices are intriguing. The concept of multiple organ support therapy (MOST) providing simultaneous and combined support for different failing organs was described more than 15 years ago by Ronco and Bellomo. This concept also implicates overcoming the “compartmentalized” approach provided by different single organ specialized professionals by a multidisciplinary and multiprofessional strategy. The idea of MOST is supported by the failure of several recent studies on single organ support including liver and lung support. Improvement of outcome by ECOS necessarily depends on optimized patient selection, integrated organ support and limitation of its side effects. This implicates challenges for engineers, industry and healthcare professionals. From a technical viewpoint, modular combination of pre-existing technologies such as renal replacement, albumin-dialysis, ECCO2R and potentially cytokine elimination can be considered as a first step. While this allows for stepwise and individual combination of standard organ support facilities, it carries the disadvantage of large extracorporeal blood volume and surfaces as well as additive costs. The more intriguing next step is an integrated platform providing the capacity of multiple organ support within one device. (This article is freely available.)

Respiratory and metabolic acidosis correction with the ADVanced Organ Support system

Background

The lung, the kidney, and the liver are major regulators of acid-base balance. Acidosis due to the dysfunction of one or more organs can increase mortality, especially in critically ill patients. Supporting compensation by increasing ventilation or infusing bicarbonate is often ineffective. Therefore, direct removal of acid may represent a novel therapeutic approach. This can be achieved with the ADVanced Organ Support (ADVOS) system, an enhanced renal support therapy based on albumin dialysis. Here, we demonstrate proof of concept for this technology.

Methods

An ex vivo model of either hypercapnic (i.e., continuous CO₂ supply) or lactic acidosis (i.e., lactic acid infusion) using porcine blood was subjected to hemodialysis with ADVOS. A variety of operational parameters including blood and dialysate flows, different dialysate pH settings, and acid and base concentrate compositions were tested. Comparisons with standard continuous veno-venous hemofiltration (CVVH) using high bicarbonate substitution fluid and continuous veno-venous hemodialysis (CVVHD) were also performed.

Results

Sixty-one milliliters per minute (2.7 mmol/min) of CO₂ was removed using a blood flow of 400 ml/min and a dialysate pH of 10 without altering blood pCO₂ and HCO₃⁻ (36 mmHg and 20 mmol/l, respectively). Up to 142 ml/min (6.3 mmol/min) of CO₂ was eliminated if elevated pCO₂ (117 mmHg) and HCO₃⁻ (63 mmol/l) were allowed. During continuous lactic acid infusion, an acid load of up to 3 mmol/min was compensated. When acidosis was triggered, ADVOS multi normalized pH and bicarbonate levels within 1 h, while neither CVVH nor CVVHD could. The major determinants to correct blood pH were blood flow, dialysate composition, and initial acid-base status.

Conclusions

In conclusion, ADVOS was able to remove more than 50% of the amount of CO₂ typically produced by an adult human. Blood pH was maintained stable within the physiological range through compensation of a metabolic acid load by albumin dialysate. These in vitro results will require confirmation in patients.

Part I: Minimum Quality Threshold in Preclinical Sepsis Studies (MQTiPSS) for Study Design and Humane Modeling Endpoints

Preclinical animal studies are mandatory before new treatments can be tested in clinical trials. However, their use in developing new therapies for sepsis has been controversial because of limitations of the models and inconsistencies with the clinical conditions. In consideration of the revised definition for clinical sepsis and septic shock (Sepsis-3), a Wiggers-Bernard Conference was held in Vienna in May 2017 to propose standardized guidelines on preclinical sepsis modeling. The participants conducted a literature review of 260 most highly cited scientific articles on sepsis models published between 2003 and 2012. The review showed, for example, that mice were used in 79% and euthanasia criteria were defined in 9% of the studies. Part I of this report details the recommendations for study design and humane modeling endpoints that should be addressed in sepsis models. The first recommendation is that survival follow-up should reflect the clinical time course of the infectious agent used in the sepsis model. Furthermore, it is recommended that therapeutic interventions should be initiated after the septic insult replicating clinical care. To define an unbiased and reproducible association between a new treatment and outcome, a randomization and blinding of treatments as well as inclusion of all methodological details in scientific publications is essential. In all preclinical sepsis studies, the high standards of animal welfare must be implemented. Therefore, development and validation of specific criteria for monitoring pain and distress, and euthanasia of septic animals, as well as the use of analgesics are recommended. A set of four considerations is also proposed to enhance translation potential of sepsis models. Relevant biological variables and comorbidities should be included in the study design and sepsis modeling should be extended to mammalian species other than rodents. In addition, the need for source control (in case of a defined infection focus) should be considered. These recommendations and considerations are proposed as "best practices" for animal models of sepsis that should be implemented.

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.