Respiratory and metabolic acidosis correction with the ADVanced Organ Support system

Extracorporeal albumin dialysis in critically ill patients with liver failure: Comparison of four different devices-A retrospective analysis

BACKGROUND

Besides standard medical therapy and critical care monitoring, extracorporeal liver support may provide a therapeutic option in patients with liver failure. However, little is known about detoxification capabilities, efficacy, and efficiency among different devices.

METHODS

Retrospective single-center analysis of patients treated with extracorporeal albumin dialysis. Generalized Estimating Equations with robust variance estimator were used to account for repeated measurements of several cycles and devices per patient.

RESULTS

Between 2015 and 2021 n = 341 cycles in n = 96 patients were eligible for evaluation, thereof n = 54 (15.8%) treatments with Molecular Adsorbent Recirculating System, n = 64 (18.7%) with OpenAlbumin, n = 167 (48.8%) Advanced Organ Support treatments, and n = 56 (16.4%) using Single Pass Albumin Dialysis. Albumin dialysis resulted in significant bilirubin reduction without differences between the devices. However, ammonia levels only declined significantly in ADVOS and OPAL. First ECAD cycle was associated with highest percentage reduction in serum bilirubin. With the exception of SPAD all devices were able to remove the water-soluble substances creatinine and urea and stabilized metabolic dysfunction by increasing pH and negative base excess values. Platelets and fibrinogen levels frequently declined during treatment. Periprocedural bleeding and transfusion of red blood cells were common findings in these patients.

CONCLUSIONS

From this clinical perspective ADVOS and OPAL may provide higher reduction capabilities of liver solutes (i.e. bilirubin and ammonia) in comparison to MARS and SPAD. However, further prospective studies comparing the effectiveness of the devices to support liver impairment (i.e. bile acid clearance or albumin binding capacity) as well as markers of renal recovery are warranted.

Trends, Advantages and Disadvantages in Combined Extracorporeal Lung and Kidney Support From a Technical Point of View

Extracorporeal membrane oxygenation (ECMO) provides pulmonary and/or cardiac support for critically ill patients. Due to their diseases, they are at high risk of developing acute kidney injury. In that case, continuous renal replacement therapy (CRRT) is applied to provide renal support and fluid management. The ECMO and CRRT circuits can be combined by an integrated or parallel approach. So far, all methods used for combined extracorporeal lung and kidney support present serious drawbacks. This includes not only high risks of circuit related complications such as bleeding, thrombus formation, and hemolysis, but also increase in technical workload and health care costs. In this sense, the development of a novel optimized artificial lung device with integrated renal support could offer important treatment benefits. Therefore, we conducted a review to provide technical background on existing techniques for extracorporeal lung and kidney support and give insight on important aspects to be addressed in the development of this novel highly integrated artificial lung device.

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.

The Pyruvate Dehydrogenase Complex in Sepsis: Metabolic Regulation and Targeted Therapy

Anaerobic glycolysis is the process by which glucose is broken down into pyruvate and lactate and is the primary metabolic pathway in sepsis. The pyruvate dehydrogenase complex (PDHC) is a multienzyme complex that serves as a critical hub in energy metabolism. Under aerobic conditions, pyruvate translocates to mitochondria, where it is oxidized into acetyl-CoA through the activation of PDHC, thereby accelerating aerobic oxidation. Both phosphorylation and acetylation affect PDHC activity and, consequently, the regulation of energy metabolism. The mechanisms underlying the protective effects of PDHC in sepsis involve the regulation on the balance of lactate, the release of inflammatory mediators, the remodeling of tricarboxylic acid (TCA) cycle, as well as on the improvement of lipid and energy metabolism. Therapeutic drugs that target PDHC activation for sepsis treatment include dichloroacetate, thiamine, amrinone, TNF-binding protein, and ciprofloxacin. In this review, we summarize the recent findings regarding the metabolic regulation of PDHC in sepsis and the therapies targeting PDHC for the treatment of this condition.

Possibility of Venous Serum Cl- Concentration ([Cl-]s) as a Marker for Human Metabolic Status: Correlation of [Cl-]s to Age, Fasting Blood Sugar (FBS), and Glycated Hemoglobin (HbA1c)

The HCO₃⁻ concentration in venous serum ([HCO₃⁻]_s) is a factor commonly used for detecting the body pH and metabolic conditions. To exactly detect [HCO₃⁻]_s, the venous CO₂ pressure should be kept as it is in the vein. The [HCO₃⁻]_s measurement is technically complicated to apply for huge numbers of almost heathy persons taking only basic medical examinations. The summation of [HCO₃⁻]_s and the venous serum Cl⁻ concentration ([Cl⁻]_s) is approximately constant; therefore, we studied if [Cl⁻]_s could be a marker detecting metabolic conditions instead of [HCO₃⁻]_s. Venous blood was obtained from persons taking basic medical examinations (the number of persons = 107,630). Older persons showed higher values of [Cl⁻]_s, fasting blood sugar (FBS), and glycated hemoglobin (HbA1c) than younger ones. [Cl⁻]_s showed positive correlation to age and negative correlation to FBS and HBA1c. The negative correlation of [Cl⁻]_s to FBS/HbA1c was obvious in persons with high FBS/HbA1c, leading us to an idea that persons with high FBS/HbA1c show high [HCO₃⁻]_s, which might be caused by low activity of carbonic anhydrase in the lung observed in persons with diabetes mellitus under acidotic conditions. Taken together, an easily measured serum electrolyte, [Cl⁻]_s, could be a useful marker estimating metabolic conditions.

Extracorporeal carbon dioxide Removal (ECCO2 R) with the Advanced Organ Support (ADVOS) system in critically ill COVID-19 patients

Disturbed oxygenation is foremost the leading clinical presentation in COVID‐19 patients. However, a small proportion also develop carbon dioxide removal problems. The Advanced Organ Support (ADVOS) therapy (ADVITOS GmbH, Munich, Germany) uses a less invasive approach by combining extracorporeal CO₂‐removal and multiple organ support for the liver and the kidneys in a single hemodialysis device. The aim of our study is to evaluate the ADVOS system as treatment option in‐COVID‐19 patients with multi‐organ failure and carbon dioxide removal problems. COVID‐19 patients suffering from severe respiratory insufficiency, receiving at least two treatments with the ADVOS multi system (ADVITOS GmbH, Munich, Germany), were eligible for study inclusion. Briefly, these included patients with acute kidney injury (AKI) according to KDIGO guidelines, and moderate or severe ARDS according to the Berlin definition, who were on invasive mechanical ventilation for more than 72 hours. In total, nine COVID‐19 patients (137 ADVOS treatment sessions with a median of 10 treatments per patient) with moderate to severe ARDS and carbon dioxide removal problems were analyzed. During the ADVOS treatments, a rapid correction of acid‐base balance and a continuous CO₂ removal could be observed. We observed a median continuous CO₂ removal of 49.2 mL/min (IQR: 26.9‐72.3 mL/min) with some treatments achieving up to 160 mL/min. The CO₂ removal significantly correlated with blood flow (Pearson 0.421; P < .001), PaCO₂ (0.341, P < .001) and HCO3‐ levels (0.568, P < .001) at the start of the treatment. The continuous treatment led to a significant reduction in PaCO₂ from baseline to the last ADVOS treatment. In conclusion, it was feasible to remove CO₂ using the ADVOS system in our cohort of COVID‐19 patients with acute respiratory distress syndrome and multiorgan failure. This efficient removal of CO₂ was achieved at blood flows up to 300 mL/min using a conventional hemodialysis catheter and without a membrane lung or a gas phase.

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.

Extracorporeal multiorgan support including CO2-removal with the ADVanced Organ Support (ADVOS) system for COVID-19: A case report

A substantial part of COVID-19-patients suffers from multi-organ failure (MOF). We report on an 80-year old patient with pulmonary, renal, circulatory, and hepatic failure. We decided against the use of extracorporeal membrane oxygenation (ECMO) due to old age and a SOFA-score of 13. However, the patient was continuously treated with the extracorporeal multi-organ- “ADVanced Organ Support” (ADVOS) device (ADVITOS GmbH, Munich, Germany). During eight 24h-treatment-sessions blood flow (100–300 mL/min), dialysate flow (160–320 mL/min) and dialysate pH (7.6–9.0) were adapted to optimize arterial PaCO₂ and pH. Effective CO₂ removal and correction of acidosis could be demonstrated by mean arterial- versus post-dialyzer values of pCO₂ (68.7 ± 13.8 vs. 26.9 ± 11.6 mmHg; p < 0.001). The CO₂-elimination rate was 48 ± 23mL/min. The initial vasopressor requirement could be reduced in parallel to pH-normalization. Interruptions of ADVOS-treatment repeatedly resulted in reversible deteriorations of p_aCO₂ and pH. After 95 h of continuous extracorporeal decarboxylating therapy the patient had markedly improved circulatory parameters compared to baseline. In the context of secondary pulmonary infection and progressive liver failure, the patient had a sudden cardiac arrest. In accordance with the presumed patient will, we decided against mechanical resuscitation. Irrespective of the outcome we conclude that extracorporeal CO₂ removal and multiorgan-support were feasible in this COVID-19-patient. Combined and less invasive approaches such as ADVOS might be considered in old-age-COVID-19 patients with MOF.

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.

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.)