Acute renal failure and multiple organ dysfunction in the ICU: from renal replacement therapy (RRT) to multiple organ support therapy (MOST)

Toward microfluidic integration of respiratory and renal organ support in a single cartridge

BACKGROUND

Extracorporeal organ assist devices provide lifesaving functions for acutely and chronically ill patients suffering from respiratory and renal failure, but their availability and use is severely limited by an extremely high level of operational complexity. While current hollow fiber-based devices provide high-efficiency blood gas transfer and waste removal in extracorporeal membrane oxygenation (ECMO) and hemodialysis, respectively, their impact on blood health is often highly deleterious and difficult to control. Further challenges are encountered when integrating multiple organ support functions, as is often required when ECMO and ultrafiltration (UF) are combined to deal with fluid overload in critically ill patients, necessitating an unwieldy circuit containing two separate cartridges.

METHODS

We report the first laboratory demonstration of simultaneous blood gas oxygenation and fluid removal in single microfluidic circuit, an achievement enabled by the microchannel-based blood flow configuration of the device. Porcine blood is flowed through a stack of two microfluidic layers, one with a non-porous, gas-permeable silicone membrane separating blood and oxygen chambers, and the other containing a porous dialysis membrane separating blood and filtrate compartments.

RESULTS

High levels of oxygen transfer are measured across the oxygenator, while tunable rates of fluid removal, governed by the transmembrane pressure (TMP), are achieved across the UF layer. Key parameters including the blood flow rate, TMP and hematocrit are monitored and compared with computationally predicted performance metrics.

CONCLUSIONS

These results represent a model demonstration of a potential future clinical therapy where respiratory support and fluid removal are both realized through a single monolithic cartridge.

Effect of extracorporeal hemoadsorption in critically ill patients with COVID-19: A narrative review

COVID-19 has been affecting the world unprecedentedly and will remain widely prevalent due to its elusive pathophysiological mechanism and the continuous emergence of new variants. Critically ill patients with COVID-19 are commonly associated with cytokine storm, multiple organ dysfunction, and high mortality. To date, growing evidence has shown that extracorporeal hemoadsorption can exert its adjuvant effect to standard of care by regulating immune homeostasis, reducing viremia, and decreasing endotoxin activity in critically ill COVID-19 cases. However, the selection of various hemofilters, timing of initiation and termination of hemoadsorption therapy, anticoagulation management of extracorporeal circuits, identification of target subgroups, and ultimate survival benefit remain controversial. The purpose of this narrative review is to comprehensively summarize the rationale for the use of hemoadsorption in critically ill patients with COVID-19 and to gather the latest clinical evidence in this field.

Clinical Assessment of Continuous Hemodialysis with the Medium Cutoff EMiC®2 Membrane in Patients with Septic Shock

INTRODUCTION

At the time of renal replacement therapy, approximately 20% of critically ill patients have septic shock. In this study, medium cutoff (MCO) continuous venovenous hemodialysis (CVVHD) was compared to high-flux membrane continuous venovenous hemodiafiltration (CVVHDF) in terms of hemodynamic improvement, efficiency, middle molecule removal, and inflammatory system activation.

METHODS

This is a monocenter crossover randomized study. Between December 31, 2017, and December 31, 2019, 20 patients with septic shock and stage 3 acute kidney injury (AKI) admitted to 2 Italian ICUs were enrolled. All patients underwent CVVHD with Ultraflux® EMiC®2 and CVVHDF with AV1000S® without washout. Each treatment lasted 24 h.

RESULTS

Compared to AV1000S®-CVVHDF, EMIC®2-CVVHD normalized cardiac index (β = -0.64; p = 0.02) and heart rate (β = 5.72; p = 0.01). Interleukin-8 and myeloperoxidase removal were greater with AV1000S®-CVVHDF than with EMiC®2-CVVHD (β = 0.35; p < 0.001; β = 0.43; p = 0.03, respectively). Leukocytosis improved over 24 h in EMiC®2-CVVHD-treated patients (β = 4.13; p = 0.03), whereas procalcitonin levels decreased regardless of the modality (β = 0.89; p = 0.01) over a 48-h treatment period. Reduction rates, instantaneous plasmatic clearance of urea, creatinine, and β2-microglobulin were similar across modalities. β2-Microglobulin removal efficacy was greater in the EMiC®2 group (β = 0-2.88; p = 0.002), while albumin levels did not differ. Albumin was undetectable in the effluent in both treatments.

DISCUSSION

In patients with septic shock and severe AKI, the efficacy of uremic toxin removal was comparable between MCO-CVVHD and CVVHDF. Further, MCO-CVVHD was associated with improved hemodynamics. Fraction of filtration and transmembrane pressure reduction and the maintenance of equal efficacy might be the key features of CVVHD with MCO membranes in critically ill patients.

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.

Continuous Renal Replacement Therapy in the Critically Ill Patient: From Garage Technology to Artificial Intelligence

The history of continuous renal replacement therapy (CRRT) is marked by technological advances linked to improvements in the knowledge of the mechanisms and kinetics of extracorporeal removal of solutes, and the pathophysiology of acute kidney injury (AKI) and other critical illnesses. In the present article, we review the main steps in the history of CRRT, from the discovery of continuous arteriovenous hemofiltration to its evolution into the current treatments and its early use in the treatment of AKI, to the novel sequential extracorporeal therapy. Beyond the technological advances, we describe the development of new medical specialties and a shared nomenclature to support clinicians and researchers in the broad and still evolving field of CRRT.

Management of Acute Kidney Injury/Renal Replacement Therapy in the Intensive Care Unit

Common causes of acute kidney injury (AKI) in the ICU setting include acute tubular necrosis (due to shock, hemolysis, rhabdomyolysis, or procedures that compromise renal perfusion), abdominal compartment syndrome, urinary retention, and interstitial nephritis. Treatment is geared toward addressing the underlying cause. Dialysis may be required if renal injury does not resolve. Early initiation of dialysis based on the stage of AKI alone has not been shown to provide a mortality benefit. Dialysis modalities are based on the dialysis indication and the patient's clinical status. Providers should pay close attention to nutritional requirements and medication dosing according to renal function and dialysis modality.

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.)

Hemofiltration in Patients with Severe Acute Pancreatitis (Review)

Questions regarding the application of extracorporeal detoxification to patients with severe acute pancreatitis have been considered. Hemodialysis, the historically first method of extracorporeal detoxification for such patients, has been also described in the review. Appropriateness of using renal replacement therapy methods and among them continued renal replacement therapy has been shown. Hemofiltration and hemodiafiltration technologies are described in detail including different modes of their application and the possibility of using various types of filters. Available data on hemofiltration for patients with severe acute pancreatitis have been analyzed. Great attention is paid to the unsolved aspects of hemofiltration in severe acute pancreatitis such as determining renal and extrarenal indices; time of starting hemofiltration; selection of volume replacement modes and a buffer system; procedure duration; anticoagulation measures, defining criteria to assess the adequacy of hemofiltration, state severity, and organ dysfunction degree. Further multicenter investigations are necessary to be able to assess the efficacy of the hemofiltration procedures on the basis of the thoroughly worked out and pathogenically grounded protocol using adequate control methods taking into consideration endogenic intoxication phases and intensity of the multiple organ failure syndrome.

The Big Bang of Hemofiltration: The Beginning of a New Era in the Third Millennium for Extra-Corporeal Blood Purification!

Since the last decade, hemofiltration and especially high volume hemofiltration has rapidly evolved from a somewhat experimental treatment towards a potentially effective “adjunctive” therapy in severe septic shock and especially refractory or catecholamine resistant hypodynamic septic shock. Nevertheless, this approach lacks prospective randomized studies (PRT'S) evaluating the critical role of early hemofiltration in sepsis. An important step forward which could be called the “big bang” in term of hemofiltration was the publication of a PRT in patients with acute renal failure (ARF) (1). Before this study (2), nobody believed that hemofiltration could change the survival rate in intensive care. Since that big bang, many physicians consider that hemofiltration at a certain dose can change the survival rate in intensive care. So the world of hemofiltration in ICU is not a definitive world, it is still in expansion. Indeed, we now have to try to define what will be the exact dose we need in septic acute renal failure. This dose might well be “higher” than 35 ml/kg/hour in the septic acute renal failure “group” as suggested by many studies (2–5). At present, it is the issue of continuous dose of high volume hemofiltration that has to be tested in future randomized studies. Since the Vicenza study (2) has shown that 35 ml/kg/h is the best dose in terms of survival, dealing with non septic acute renal failure in ICU, several studies from different groups have shown that, in septic acute renal failure, a higher dose might correlate with better survival. This has also been shown in some way by the study of the “Vicenza group” but not with a statistically significant value (2). New PRT'S have just started in Europe like the IVOIRE study (hIgh VOlume in Intensive caRE) (6) and the RENAL study. Another large study is looking more basically at dose in non septic acute renal failure in Australasia and is led by the group of Rinaldo Bellomo in Melbourne (7) as well as the ATN study (8) led by Palevsky and colleagues in the USA, also testing the importance of dose in the treatment for ARF. Nevertheless, “early goal-directed hemofiltration therapy” like early goal directed therapy (9) has to be studied in our critical ill patients. Regarding this issue, fewer studies, mainly retrospective exist, but again the IVOIRE study (6) will address this issue by studying septic patients with acute renal injury according to the Rifle classification (10). So, this review focuses on the early application and on the adequate dose of continuous high volume hemofiltration in septic shock in order to improve not only hemodynamics, but survival in this very severely ill cohort of patients. This could well be called the “big bang of hemofiltration” as one could never have anticipated that an adequate dose of hemofiltration could markedly influence the survival rate of ICU-septic acute renal failure patients. On top of the use of early and adequate dose of hemofiltration in sepsis, a higher dose could also provide better renal recovery rate and reduce the risk of associate chronic dialysis in these patients. Furthermore, this paper also reviews “brand” new theories regarding the rationale for hemofiltration in sepsis. Finally, this paper also addresses the so-called negative studies as well anticipated side effects.

First Clinical Trial for a New Crrt Machine: The Prismaflex

A new CRRT machine has been designed to fulfill the expectations of nephrologists and intensivists operating in the common ground of critical care nephrology. The new equipment is called “Prismaflex” (Gambro-Dasco, Mirandola, Modena) and it is the natural evolution of the Prisma machine that has been utilized worldwide for CRRT in the last decade.

We performed a preliminary “alfa trial” to establish usability, flexibility and realiability of the new device. Accuracy was also tested by recording various operational parameters during different intermittent and continuous renal replacement modalities. Forty-one runs were conducted on 13 patients and the difference between delivered and prescribed parameters was always lower than 2%. We concluded that the new Prismaflex is a well designed new machine for CRRT and can be safely and effectively utilized in the critical care nephrology setting.

Plasma Filtration Adsorption Dialysis (PFAD): A New Technology for Blood Purification

Severe sepsis is one of the most significant challenges in critical care. Despite all the developments achieved in infectious diseases and critical care, along with numerous attempts to develop treatments, the mortality rate of severe sepsis and septic shock remains unacceptably high. The pathophysiology of severe sepsis and septic shock is only partially understood. Circulating pro-inflammatory and anti-inflammatory mediators appear to participate in the complex cascade of events which leads to deranged microcirculatory function, as we know from the peak concentration hypothesis.

Therapeutic trials targeting single pro-inflammatory and anti-inflammatory mediators failed to demonstrate any benefit, suggesting that the unselective removal of different mediators may be a more appropriate approach.

In severe sepsis several blood purification techniques, such as continuous hemofiltration (CVVH), high volume hemofiltration (HVHF), pulse high volume hemofiltration (HVHF), plasma filtration, plasma adsorption, coupled plasma filtration adsorption (CPFA), have been proposed but such techniques appear to have both theorical as well as practical limitations.

Plasma Filtration Adsorption Dialysis (PFAD) is a new extracorporeal treatment which combines different principles of blood purification in a single device. The core of this technique is a new dialyzer composed by three suitable compartments that provide specific functions. The association of multiple principles permits specific removal of molecules implicated in the pathophysiology of patient's disease and re-establishment of hydro-electrolyte, acid-base equilibrium, if renal dysfunction-failure is present. The final target of PFAD is to obtain complete purification by combining principles of physics and chemistry to remove hydrophilic and hydrophobic molecules with a very wide range of weights.

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

Background

Novel extracorporeal procedures are constantly being developed and evaluated for use in patients with sepsis. Preclinical evaluation of such procedures usually requires testing in large animal models. In the present work, the safety and efficacy of a recently developed ADVanced Organ Support (ADVOS) system in a newly developed large animal two-hit model of liver failure combined with endotoxemia were tested.

Methods

After establishing the model in more than 50 animals, a randomized study was performed. An inflammatory cholestatic liver injury was initially provoked in pigs. Three days after surgery, endotoxin was gradually administered during 7½ h. Animals were randomized to receive standard medical treatment either with (ADVOS group, n = 5) or without ADVOS (control group, n = 5). The ADVOS treatment was started 2½ h after endotoxemia and continued for 7 h. Survival, cardiovascular, respiratory, renal, liver, coagulation, and cerebral parameters were analyzed.

Results

Three days after surgery, cholestatic injury resulted in hyperbilirubinemia [5.0 mg/dl (IQR 4.3–5.9 mg/dl)], hyperammonemia [292 μg/dl (IQR 291–296 μg/dl)], leukocytosis [20.2 10³/μl (IQR 17.7–21.8 10³/μl)], and hyperfibrinogenemia [713 mg/dl (IQR 654–803 mg/dl)]. After endotoxemia, the ADVOS procedure stabilized cardiovascular, respiratory, and renal parameters and eliminated surrogate markers as bilirubin [2.3 (IQR 2.3–3.0) vs. 5.5 (IQR 4.6–5.6) mg/dl, p = 0.001] and creatinine [1.4 (IQR 1.1–1.7) vs. 2.3 (IQR 2.1–3.1) mg/dl, p = 0.01]. Mortality: All animals in the ADVOS group survived, while all animals in the control group expired during the 10-h observation period (p = 0.002). No adverse events related to the procedure were observed.

Conclusions

The ADVOS procedure showed a promising safety and efficacy profile and improved survival in a sepsis-like animal model with dysfunction of multiple organs. An amelioration of major organ functions (heart and lung) combined with removal of markers for kidney and liver function was observed.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-017-0144-3) contains supplementary material, which is available to authorized users.

Continuous Renal Replacement Therapy: Forty-year Anniversary

In 1977 Peter Kramer performed the first CAVH (continuous arteriovenous hemofiltration) treatment in Gottingen, Germany. CAVH soon became a reliable alternative to hemo- or peritoneal dialysis in critically ill patients. The limitations of CAVH spurred new research and the discovery of new treatments such as CVVH and CVVHD (continuous veno-venous hemofiltration and continuous veno-venous hemodialysis). The alliance with industry led to development of new specialized equipment with improved accuracy and performance in delivering continuous renal replacement therapies (CRRTs). Machines and filters have progressively undergone a series of technological steps, reaching a high level of sophistication. The evolution of technology has continued, leading to the development and clinical application of new membranes, new techniques and new treatment modalities. With the progress of technology, the entire field of critical care nephrology moved forward, expanding the areas of application of extracorporeal therapies to cardiac, liver and pulmonary support. A great deal of research made extracorporeal therapies an interesting option for the treatment of sepsis and intoxication and the additional use of sorbents was explored. With the progress in understanding the pathophysiology of acute kidney injury (AKI), new guidelines were developed, driving indications, modalities of prescription, monitoring techniques and quality assurance programs. Information technology and precision medicine have recently contributed to further evolution of CRRT, with the possibility of collecting data in large databases and evaluating policies and practice patterns. This is likely to ultimately result in improved patient care. CRRTs are 40 years old today, but they are still young and full of potential for further evolution.

(R)evolution in the Management of Acute Kidney Injury in Newborns

The application of continuous renal replacement therapy (CRRT) in children, before roller pumps and dialysis monitors were available in the intensive care unit, was realized by continuous arteriovenous hemofiltration. Then hemofiltration was coupled with dialysis in order to increase dialytic dose and system efficiency, and the circuit and filters were specifically modified to optimize patency and session life span. After about 30 years, another revolution is ongoing, in that pediatric acute kidney injury (AKI) and fluid accumulation (for which critically ill newborns and children with multiple-organ dysfunction are greatly at risk) are recognized as independently associated with mortality and identified as primary conditions to prevent and aggressively treat. Today, novel technology specifically dedicated for very young patients will allow feasible and straightfoward application of CRRT to infants and children. This article discusses the authors' personal perspectives on how clinical and technical issues of dialysis in children have been addressed and how today, severe pediatric AKI can be managed with accurate and safe CRRT machines that will likely yield outcome improvements in the coming decades.

Continuous renal replacement therapy (CRRT) for rhabdomyolysis

BACKGROUND

Rhabdomyolysis is a condition that is characterised by the breakdown of skeletal muscle tissue and leakage of intracellular myocyte contents into circulating blood. Rhabdomyolysis can lead to acute kidney injury (AKI) and is a potentially life-threatening condition. Studies have indicated that continuous renal replacement therapy (CRRT) may provide benefits for people with rhabdomyolysis by removing potentially damaging myoglobin and stabilising haemodynamic and metabolic status.

OBJECTIVES

We aimed to: i) assess the efficacy of CRRT in removing myoglobin; ii) investigate the influence of CRRT on mortality and kidney-related outcomes; and iii) evaluate the safety of CRRT for the treatment of people with rhabdomyolysis.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 6 January 2014 through contact with the Trials' Search Co-ordinator using search terms relevant to this review. We also searched China National Knowledge Infrastructure (from 1 January 1979 to 16 April 2013) and the Chinese Clinical Trials Register (to 16 April 2013).

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs that investigated clinical outcomes of CRRT for people with rhabdomyolysis were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion and extracted data. We derived risk ratios (RR) for dichotomous data and mean differences (MD) for continuous data with 95% confidence intervals (CI). Methodological risk of bias was assessed using the Cochrane risk of bias tool.

MAIN RESULTS

Of the three included studies (101 participants), one evaluated continuous arteriovenous haemodialysis and two investigated continuous venovenous haemofiltration; all included conventional therapy as control.We found significant decreases in myoglobin in patients among whom CRRT therapy was initiated on days four, eight, and 10 (day 4: MD -11.00 (μg/L), 95% CI -20.65 to -1.35; Day 8: MD -23.00 (μg/L), 95% CI -30.92 to -15.08; day 10: MD -341.87 (μg/L), 95% CI -626.15 to -57.59) compared with those who underwent conventional therapy.Although CRRT was associated with improved serum creatinine, blood urea nitrogen, and potassium levels; reduced duration of the oliguria phase; and was associated with reduced time in hospital, no significant differences were found in mortality rates compared with conventional therapy (RR 0.17, 95% CI 0.02 to 1.37). The included studies did not report on long-term outcomes or prevention of AKI.Overall, we found that study quality was suboptimal: blinding and randomisation allocation were not reported by any of the included studies, leading to the possibility of selection, performance and detection bias.

AUTHORS' CONCLUSIONS

Although CRRT may provide some benefits for people with rhabdomyolysis, the poor methodological quality of the included studies and lack of data relating to clinically important outcomes limited our findings about the effectiveness of CRRT for people with rhabdomyolysis.There was insufficient evidence to discern any likely benefits of CRRT over conventional therapy for people with rhabdomyolysis and prevention of rhabdomyolysis-induced AKI.

A new machine for continuous renal replacement therapy: from development to clinical testing

A new continuous renal replacement therapy machine has been designed to fulfill the expectations of nephrologists and intensivists operating in the common ground of critical care nephrology. The new equipment is called Prismaflex and it is the natural evolution of the PRISMA machine that has been utilized worldwide for continuous renal replacement therapy in the last 10 years. The authors performed a preliminary alpha-trial to establish the usability, flexibility and reliability of the new device. Accuracy was also tested by recording various operational parameters during different intermittent and continuous renal replacement modalities during 62 treatments. This article will describe our first experience with this new device and touch upon the historic and technologic background leading to its development.

Cytokine removal on extracorporeal life support for treatment of acute endotoxemia: a randomized controlled animal study

BACKGROUND

We prospectively evaluated the effectiveness of resin adsorption incorporated in an extracorporeal life support (ELS) circuit in an animal model of sepsis for removal of cytokines and prevention of hemodynamic deterioration during the treatment of septic shock.

METHODS

Twelve female landrace pigs were randomly assigned to two groups, a study group(n=6), treated with high-flow resin adsorption (300 mL/min) and ELS, and a control group (n=6), treated only with ELS. Septic shock was induced by intravenous 0.02 μg/kg/min infusion was of Escherichia coli lipopolysaccharide (LPS). Measurements were carried out in the study group at baseline, at the end of LPS injection(t0) at 30(t1), 60(t2), 90(t3) and 120 min (t4) and 60 min after stopping resin-adsorption (t5). In the control group measurements were performed at baseline (t0), t1 and only t2, as no control animal survived beyond this latter experimental timepoint.

RESULTS

The final population consisted of 9 animals, five in the study group and 4 in the control group. Plasma values of both tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) were reduced during resin-adsorption (t1-t4) while these mediators increased in controls undergoing ELS only. With a clearance of TNF-α of 15,233 pg/min and IL-6 of 10,233 pg/min, 79.2% of TNF-α and 95.3% of IL-6 produced were adsorbed. Systemic vascular resistance decreased significantly in both groups at t0. While it further was reduced during the control experiments at t1 and t2, it returned to normal in the study animals. Cardiac output increased at t0, t1 and t2 in the control experiments. In contrast, in study animals after a peak at t0, it returned to the baseline value and did not vary thereafter.

CONCLUSIONS

Combined resin-adsorption and ELS improved hemodynamics resulting from effective removal of inflammatory mediators in a pig model of septic shock.

Simplified regional citrate anticoagulation using a calcium-containing replacement solution for continuous venovenous hemofiltration

Regional citrate anticoagulation (RCA) is not widely used because it requires complex therapeutic modalities, a specialized calcium-free replacement solution, and continuous intravenous calcium infusion. We designed a simplified protocol for RCA using a commercial calcium-containing replacement solution for continuous venovenous hemofiltration (CVVH). Thirty-six patients were treated with RCA-based pre-dilution CVVH using a calcium-containing replacement solution (ionized calcium 1.50 mmol/L). We pumped a 4 % trisodium citrate solution into the arterial line of extracorporeal circulation at a starting rate of 200 mL/h while adjusting the rate to achieve a post-filter ionized calcium level of between 0.25 and 0.5 mmol/L. The initial blood flow was set at 150 mL/min. The replacement solution was delivered at 35 mL/kg/h. We measured the serum and effluent citrate concentration during CVVH at 0, 24, 48, and 72 h. The mean hemofilter survival was 61.3 ± 21.6 h (range 14-122 h). The mean 4 % trisodium citrate solution pumped was 207 (190-230) mL/h, and the mean pre-filter and post-filter ionized calcium levels were 0.96-1.02 and 0.34-0.38 mmol/L, respectively. Ninety-two, 63, and 48 % of the hemofilters were patent at 24, 48, and 72 h. The mean serum citrate concentration was not significantly different at 24, 48, and 72 h. No bleeding episodes were found, and no patient showed the symptoms and signs of hypocalcemia or citrate toxicity. Our simplified RCA protocol using a calcium-containing replacement solution for CVVH is effective and safe, and obviates the need for a separate peripheral or central venous catheter for continuous intravenous calcium infusion.

Use of high-volume haemodiafiltration in patients with refractory septic shock and acute kidney injury

Background

High-volume haemofiltration (HVHF) has been used successfully in animal models with sepsis, and preliminary data have shown that this technique may improve the haemodynamics in patients with refractory septic shock. We used high-volume continuous venovenous haemodiafiltration (CVVHDF) in patients with acute kidney injury (AKI) and refractory septic shock to evaluate their outcome when compared with their prognosis predicted by scores of severity.

Methods

This is a cohort study in a Medical and Surgical Intensive Care Unit. Fifty-five patients with refractory septic shock and AKI were included in the study.

Results

High-volume CVVHDF was started in patients with AKI and septic shock requiring norepinephrine dose >0.2 µg/kg/min. AKI was classified according to the RIFLE criteria. Treatment was implemented within the first 24 h of refractory septic shock with a dialysis dose of 70 mL/kg/h until reversal of shock or death. Fifty-five patients were treated with high-volume CVVHDF with an observed mortality of 63%, similar to the mortality predicted by the APACHE II and SAPS II scores.

Conclusion

Survival rate in our patients with AKI and refractory septic shock treated with high-volume CVVHDF was identical to survival predicted by the severity scores. Treatment with high-volume haemodiafiltraton is applicable to severely ill patients with septic shock but does not confer any clear advantage in terms of survival. This therapy should not be implemented on a routine basis in patients with AKI and refractory septic shock.

Myoglobin clearance by continuous venous-venous haemofiltration in rhabdomyolysis with acute kidney injury: a case series

BACKGROUND

Clearance of circulating myoglobin is a critical measure to prevent further damage in patients with rhabdomyolysis (RM) and acute kidney injury (AKI). Continuous venous-venous haemofiltration has emerged to be a novel approach for this purpose. The objective of present study is to evaluate the efficacy and safety of CVVH in myoglobin clearance for patients with RM complicated with AKI.

METHOD

We prospectively analysed 15 patients with acute RM and AKI due to crush syndrome (n=7), bee stings (n=5), polymyositis (n=2) and heroin poisoning (n=1). All of them presented oliguria with high serum myoglobin and creatine kinase concentration. They were treated by CVVH for at least 48h until the conditions turned to be stable, then replaced by intermittent renal replacement therapy (intermittent haemofiltration or haemodialysis). Meanwhile intravascular volume expansion, urinary alkalinisation, and forced diuresis were administered. During the procedure, serum and effluent concentrations of myoglobin and creatinine were measured simultaneously at 2, 6, 12 and 24h.

RESULT

The mean sieving coefficients for myoglobin were 0.28±0.06, 0.21±0.06, 0.15±0.02 and 0.11±0.02 during 2, 6, 12 and 24h of CVVH intervention, whilst mean clearance of myoglobin was 14.3±3.1ml/min during 2h and reduced to 11.5±3.2, 7.5±0.9, 5.6±1.0ml/min during 6, 12 and 24h. In contrast to myoglobin, the sieving coefficient for creatinine remained stable at 0.95±0.25, 1.02±0.12, 0.89±0.32, 0.98±0.27 during 24h of CVVH. In all of the 15 patients, serum myoglobin and creatine kinase were dramatically decreased in 24h (-56.2 and -32.1%), 3 days (-72.9 and -50.3%) and in 7 days (-97.6 and -96.7%). Seven patients (46.7%) complicated with hypophosphatemia during CVVH intervention improved in natural course after the cessation of CVVH. After 16±12 days, all of 15 patients came to polyuria stage and finally, discharged with normal renal function after 31±15 days.

CONCLUSION

Our study showed CVVH can be employed to clear myoglobin effectively in patients with RM and AKI and presented oliguria. This indicate that CVVH would be better than other modes of renal replement treatment in acute RM with AKI because of the additional benefit of myoglobin removal, but large sample randomised controlled trials are still required to confirm it.

New insights regarding rationale, therapeutic target and dose of hemofiltration and hybrid therapies in septic acute kidney injury

Mediator removal from tissue (capillary blood compartment, CABC) and transport to the central circulation (central blood compartment, CEBC) must be effective. Effectiveness through a passive mechanism seems unlikely as the surface of CEBC (30 m(2)) is smaller than CABC (300 m(2)) whereby the former will be a limiting factor in passive transport. According to studies, a high exchange volume can induce an 80-fold increase in lymphatic flow. This results in displacement (active transport) of mediators to CEBC. Recent studies have shown that the delivered dose constitutes the mainstay of continuous renal replacement therapy. However, these results are not likely to change the recommendation: 35 ml/kg/h, adjusted for predilution, in septic acute kidney injury (AKI). Recently, studies were focusing on global intensive care unit AKI. In non-septic AKI, those studies show that 20-25 ml/kg/h was optimal. The DO-RE-MI trial underscored the importance of delivery which could be obtained by targeting doses between 5 and 10 ml/kg/h higher than prescribed. Until the IVOIRE trial becomes available, septic AKI should be treated by continuous veno-venous hemofiltration at 35 ml/kg/h. In non-septic AKI, 25 ml/kg/h remains optimal.

[Outcome of critically ill patients with acute renal failure and multiple organ failure treated with continuous venovenous haemodiafiltration]

OBJECTIVE

Acute renal failure (ARF) is associated to multiple organ failure (MOF) in critically ill patients and its mortality is high. The main objective was to evaluate the outcome of critically ill patients with ARF and MOF treated with continuous venovenous hemodiafiltration (CVVHDF).

DESIGN

Retrospective and observational study on critically ill patients.

SETTING

Medical-surgical Intensive Care Unit (ICU) in a University Hospital of Girona.

PATIENTS

Patients admitted in ICU that developed ARF and MOF and were treated with CVVHDF.

PRIMARY VARIABLES OF INTEREST

We collected data on demographic, and severity and organic dysfunction scores (SOFA). To study the risk factors for mortality, a comparative and multiple regression statistical analysis was performed, with the main effect of the study being mortality at 30 days.

RESULTS

We studied 139 patients. The most frequent predisposing factors were hypotension (98%) and sepsis (82%). the most frequently affected organs were cardiocirculatory (94%) and respiratory (47%) associated to ARF. Mean SOFA score was 11.4 + or - 2.7 points. Survival was better in traumatic and in non-oliguric patients. The 30-day mortality was 61% and the logistic regression analysis showed that age > or = 60 years [OR=3.3 (95% CI 95=1.5-7.0)] and SOFA score > or = 11 points [OR=2.5 (95% CI=1.1-5.3)] were related to mortality.

CONCLUSIONS

The mortality rate of critically ill patients with acute renal failure and multiple organ failure remains high. Traumatic and non-oliguric patients have a better survival. Age > or = 60 years and SOFA > or = 11 points were independent risk factors associated with mortality.

The future of extracorporeal support

Extracorporeal therapy has expanded significantly over the past few decades from solely artificial renal replacement therapy. In patients with multiple organ dysfunction syndrome, it becomes necessary to provide multiple organ support therapy. Technological advances have opened the door to a multifaceted intervention directed at supporting the function of multiple organs through the treatment of blood. Indications for "old" therapies such as hemofiltration and adsorption have been expanded, and using these therapies in combination further enhances blood detoxification capabilities. Furthermore, new devices are constantly in development. Nanotechnology allows us to refine membrane characteristics and design innovative monitoring/biofeedback devices. Miniaturization is leading down the path of wearable/implantable devices. With the incorporation of viable cells within medical devices, these instruments become capable not only of detoxification but synthetic functions as well, bringing us closer to the holy grail of complete replacement of organ function. This article provides a brief overview of current and future direction in extracorporeal support in the critical care setting.

Renal recovery after severe acute renal failure

BACKGROUND

There is limited information about renal recovery to independence from renal replacement therapy (RRT) and about factors associated with its occurrence after severe acute renal failure (ARF).

METHODS

We conducted a population-based surveillance among all adult residents of the Calgary Health Region surviving ICU admission from May 1, 1999 to April 30, 2002. The primary objective was to determine the rate of and the factors associated with 90-day survival and recovery to independence from RRT in critically ill patients with severe ARF.

RESULTS

At 90 days, 96 patients (40%) were alive. Of these, 72% were RRT independent with most (87%) requiring <4 weeks to recover. Prior to RRT, the median (IQR) serum creatinine and mean (SD) serum urea were 395 (252-517) micromol/L and 29.2 (18) mmol/L, respectively. Oliguria was present in 76%. Intermittent hemodialysis was the initial modality in 46% and continuous renal replacement therapy (CRRT) in 54%. By multivariate analysis, male sex (odds ratio (OR) 7.6, 95% CI, 2.2-27, p=0.01) and a diagnosis of septic shock (OR 3.9, 95% CI 1.02-14.5, p=0.05) were associated with an increased odds of recovery. Conversely, a higher Charlson co-morbidity index score (OR 0.71, 95% CI, 0.6-0.85, p=0.04) and a higher pre-RRT serum creatinine (OR 0.20, 95% CI, 0.05-0.80, p=0.02, p=0.02) were associated with reduced odds of recovery. Chronic kidney disease or the initial modality of RRT were not associated with recovery.

CONCLUSIONS

The majority of severe ARF patients who survive their acute illness are independent of RRT by 90 days. Male sex and a diagnosis of septic shock are independently associated with recovery while a greater co-morbidity score and a higher serum creatinine prior to RRT are predictive of non-recovery.

Efficacy and safety of a low-flow veno-venous carbon dioxide removal device: results of an experimental study in adult sheep

Introduction

Extracorporeal lung assist, an extreme resource in patients with acute respiratory failure (ARF), is expanding its indications since knowledge about ventilator-induced lung injury has increased and protective ventilation has become the standard in ARF.

Methods

A prospective study on seven adult sheep was conducted to quantify carbon dioxide (CO₂) removal and evaluate the safety of an extracorporeal membrane gas exchanger placed in a veno-venous pump-driven bypass. Animals were anaesthetised, intubated, ventilated in order to reach hypercapnia, and then connected to the CO₂ removal device. Five animals were treated for three hours, one for nine hours, and one for 12 hours. At the end of the experiment, general anaesthesia was discontinued and animals were extubated. All of them survived.

Results

No significant haemodynamic variations occurred during the experiment. Maintaining an extracorporeal blood flow of 300 ml/minute (4.5% to 5.3% of the mean cardiac output), a constant removal of arterial CO₂, with an average reduction of 17% to 22%, was observed. Arterial partial pressure of carbon dioxide (PaCO₂) returned to baseline after treatment discontinuation. No adverse events were observed.

Conclusion

We obtained a significant reduction of PaCO₂ using low blood flow rates, if compared with other techniques. Percutaneous venous access, simplicity of circuit, minimal anticoagulation requirements, blood flow rate, and haemodynamic impact of this device are more similar to renal replacement therapy than to common extracorporeal respiratory assistance, making it feasible not only in just a few dedicated centres but in a large number of intensive care units as well.

Recent evolution of renal replacement therapy in the critically ill patient

The epidemiology of severe acute renal failure has dramatically changed in the past decade. Its leading cause is sepsis and the syndrome develops mostly in the intensive care unit as part of multiple organ dysfunction syndrome. After the significant improvements obtained from the mid 1970s to the mid 1990s, the past decade has seen a dramatic evolution in technology leading to new machines and new techniques for renal and multiple organ support. Extracorporeal therapies are now performed using adequate treatment doses, which have resulted in improved survival in the general population. At the same time, patients with sepsis seem to benefit from the use of increased doses, as in the case of high-volume hemofiltration or of increased membrane permeability and sorbents as in the case of continuous plasmafiltration adsorption. The humoral theory of sepsis and the peak concentration hypothesis have spurred a significant interest in the use of such extracorporeal therapies for renal support and possibly for the therapy of sepsis. Ongoing research and prospective studies will further elucidate the role of such therapies in this setting.

Consensus development in acute renal failure: The Acute Dialysis Quality Initiative

PURPOSE OF REVIEW

Although acute renal failure is both common and highly lethal in the intensive care unit, our understanding of the epidemiology and pathophysiology of acute renal failure is limited, and treatment for acute renal failure is extremely variable around the world. The general lack of consensus with regard to definitions, prevention, and treatment of acute renal failure has limited progress in this field.

RECENT FINDINGS

Consensus in acute renal failure requires establishing a framework in which intensivists, nephrologists, pharmacologists, and others who care for critically ill patients with or at risk for acute renal failure can reach consensus and develop evidence-based practice guidelines. The Acute Dialysis Quality Initiative seeks to provide an objective, dispassionate distillation of the literature and description of the current state of practice of dialysis and related therapies as they are applied to acutely ill patients. The purposes of Acute Dialysis Quality Initiative are first, to develop a consensus of opinion, with evidence where possible, on best practice; and second, to articulate a research agenda to focus on important unanswered questions.

SUMMARY

Broad consensus in the diagnosis and management of acute renal failure and in the use of blood purification in nonrenal critical illness is achievable. Standardization of definitions, practice, and research methodology is urgently needed, and specific proposals have been made by an international, interdisciplinary group.

Acute renal failure in children and infants

PURPOSE OF REVIEW

This review provides an overview of various topics related to acute renal failure and summarizes the results of recent advancements of particular significance in the care of children with acute renal failure.

RECENT FINDINGS

Over the past two decades, the treatment and prognosis of children with acute renal failure has notably shifted owing to advances in continuous treatment modalities, improvements in vascular access, and increased acknowledgment and understanding of the importance of optimizing nutritional support.

SUMMARY

After discussing the various causes of acute renal failure in children and infants, this review focuses on recent advancements in the management of acute renal failure, including acute dialysis modalities and continuous renal replacement therapy.

Influence of continuous veno-venous hemofiltration on the course of acute pancreatitis

AIM: To investigate whether continuous veno-venous hemofiltration (CVVH) in different filtration rate to eliminate cytokines would result in different efficiency in acute pancreatitis, whether the saturation time of filter membrane was related to different filtration rate, and whether the onset time of CVVH could influence the survival of acute pancreatitis.

METHODS: Thirty-seven patients were classified into four groups randomly. Group 1 underwent low-volume CVVH within 48 h of the onset of abdominal pain (early CVVH, n = 9). Group 2 received low-volume CVVH after 96 h of the onset of abdominal pain (late CVVH, n = 10). Group 3 underwent high-volume CVVH within 48 h of the onset of abdominal pain (early CVVH, n = 9). Group 4 received high-volume CVVH after 96 h of the onset of abdominal pain (late CVVH, n = 9). CVVH was sustained for at least 72 h. Blood was taken before hemofiltration, and ultrafiltrate was collected at the start of CVVH and every 12 h during CVVH period for the purpose of measuring the concentrations of TNF-α, IL-1β and IL-6. The concentrations of TNF-α, IL-1β and IL-6 were measured by swine-specific ELISA. The Solartron 1 255 B frequency response analyzer (British) was used to observe the resistance of filter membrane.

RESULTS: The survival rate had a significant difference (94.44% vs 68.42%, P<0.01) high-volume and low-volume CVVH patients. The survival rate had also a significant difference (88.89% vs 73.68%, P<0.05) between early and late CVVH patients. The hemodynamic deterioration (MAP, HR, CVP) was less severe in groups 4 and 1 than that in group 2, and in group 3 than in group 4. The adsorptive saturation time of filters membranes was 120-180 min if the filtration rate was 1 000-4 000 mL/h. After the first, second and third new hemofilters were changed, serum TNF-α concentrations had a negative correlation with resistance (r: -0.91, -0.89, and -0.86, respectively in group 1; -0.89, -0.85, and -0.76, respectively in group 2; -0.88, -0.92, and -0.82, respectively in group 3; -0.84, -0.87, and -0.79, respectively in group 4). The decreasing extent of TNF-α, IL-1β and IL-6 was significantly different between group 3 and group 1 (TNF-α P<0.05, IL-1β P<0.05, IL-6 P<0.01), between group 4 and group 2 (TNF-α P<0.05, IL-1β P<0.05, IL-6 P<0.01), between group 1 and group 2 (TNF-α P<0.05, IL-1β P<0.05, IL-6 P<0.05), and between group 3 and group 4 (TNF-α P<0.01, IL-1β P<0.01, IL-6 P<0.05), respectively during CVVH period. The decreasing extent of TNF-α and IL-1β was also significantly different between survival patients and dead patients (TNF-α P<0.05, IL-1β P<0.05). In survival patients, serum concentration of TNF-α and IL-1β decreased more significantly than that in dead patients.

CONCLUSION: High-volume and early CVVH improve hemodynamic deterioration and survival in acute pancreatitis patients. High-volume CVVH can eliminate cytokines more efficiently than low-volume CVVH. The survival rate is related to the decrease extent of TNF-α and IL-1β. The adsorptive saturation time of filter membranes are different under different filtration rate condition. The filter should be changed timely once filter membrane adsorption is saturated.

Adjunctive therapies in sepsis: An evidence-based review

OBJECTIVE

In 2003, critical care and infectious disease experts representing 11 international organizations developed management guidelines for adjunctive therapies in sepsis that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and to improve outcome in severe sepsis.

DESIGN

The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee.

METHODS

The modified Delphi methodology used for grading recommendations built on a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along five levels to create recommendation grades from A to E, with A being the highest grade. Pediatric considerations to contrast adult and pediatric management are in the article by Parker et al. on p. S591.

CONCLUSION

Glycemic control (maintenance of glucose <150 mg/dL) is recommended. The beneficial effect of glycemic control appears to be related control of glucose and not the administration of insulin. Glycemic control should be combined with a nutritional protocol. The dialysis dose is important in sepsis-induced acute renal failure. Continuous hemofiltration offers easier management of fluid balance in hemodynamically unstable septic patients but in the absence of hemodynamic instability is equivalent to intermittent hemodialysis. It is uncertain whether high-volume hemofiltration improves prognosis in sepsis. Bicarbonate therapy is not recommended for the purpose of improving hemodynamics or reducing vasopressor requirements in the presence of lactic academia and pH >7.15.

MARS therapy in critically ill patients with advanced malignancy: a clinical and technical report

BACKGROUND/METHODS

Molecular Adsorbent Recirculating System (MARS) was used in three consecutive critically ill patients at the Singapore General Hospital with advanced malignancy and acute liver failure (ALF). Case 1 was a male patient with hepatocellular carcinoma (HCC) for which initial right hepatectomy was followed by left hepatectomy 5 months later for recurrent HCC. The postoperative course following second surgery was complicated by severe methicillin-resistant Staphylococcus aureus (MRSA) sepsis, mild azotaemia and subacute cholestatic liver failure. MARS was used thrice in this patient. Case 2 was a female patient with advanced acute lymphoblastic leukaemia (ALL) with post bone marrow transplantation (BMT) acute haemolytic-uraemic syndrome (HUS) secondary to cyclosporin A (Cy A), cytomegalovirus (CMV) infection, severe nosocomial pneumonia, acute renal failure (ARF) treated with continuous haemofiltration and acute veno-occlusive disease resulting in Budd-Chiari syndrome. The latter precipitated ALF. MARS was instituted twice. Case 3 was a male patient with advanced, refractory Hodgkin's disease previously treated with multiple courses of chemotherapy. ALF developed secondary to acute viral hepatitis B flare. He was given a trial of MARS once in the ICU. All the three patients eventually died.

RESULTS

Mean MARS intradialytic systemic pressures were as follows: systolic pressure range was 95 +/- 17 to 128 +/- 17 mmHg and diastolic pressure range was 51 +/- 5 to 67 +/- 7 mmHg. Pressure at albumin dialysate exit point from dialyser 1 (Ae) ranged from 253 +/- 11 to 339 +/- 15 mmHg and that at albumin dialysate entry point into dialyser 1 (Aa) ranged from 142 +/- 11 to 210 +/- 6 mmHg. Ultrafiltration (UF) was 633 +/- 622 mL over mean treatment duration of 6.3 +/- 0.9 h with a total heparin dose of 1583 +/- 817 IU. Coagulation status pre- and 6-h post-MARS was similar: aPTT (P=0.116) and platelet count (P=0.753). There were no bleeding complications or circuit thromboses. MARS had a significant de-uraemization effect (pre- and post-MARS serum creatinine and urea: P=0.046 and 0.028, respectively) but did not significantly attenuate blood lactate, ammonia or total bilirubin levels. Albumin dialysate (Ae - Aa) urea and creatinine concentrations appeared to be sharply attenuated after 6 h of MARS. In contrast, the removal of total bilirubin by albumin dialysate from the blood compartment appeared to plateau after 4 h of continuous MARS operation.

CONCLUSIONS

MARS was well-tolerated in critically ill patients with advanced and complicated cancer. Low-dose heparin was safe and did not compromise MARS circuit integrity. Although MARS had a significant de-uraemization effect, this appeared to be limited by the duration of MARS operation. Our data suggested that such a limit was reached earlier for total bilirubin. More data are needed to confirm the present findings and further delineate the saturation limit of MARS for different toxins that accumulate in ALF. This would affect the optimal duration of MARS therapy.

Artificial organ treatment for multiple organ failure, acute renal failure, and sepsis: recent new trends

Sepsis remains the major cause of mortality worldwide, claiming millions of lives each year. The past decade has seen major advances in the understanding of the biological mechanisms involved in this complex process. Unfortunately, no definitive therapy yet exists that can successfully treat sepsis and its complications. At variance with targeting single mediators, therapeutic intervention aimed at the nonselective removal of pro- and anti-inflammatory mediators seems a rational concept and a possible key to successful extracorporeal therapies. A further advantage may lie in the continuous nature of such therapy. With such continuous therapy, sequentially appearing peaks of systemic mediator overflow may be attenuated and persistently high plasma levels reduced. This theoretical framework is proposed as the underlying biological rationale for a series of innovative modalities in sepsis. In this editorial, we will review recent animal and human trials that lend support to this concept. We will also review the importance of treatment dose during continuous renal replacement therapy as a major factor affecting survival in critically ill patients with acute renal failure. Additionally, we will review novel information related to other blood purification techniques using large pore membranes or plasma filtration with adsorbent perfusion. Although these approaches are still in the early stages of clinical testing, they are conceptually promising and might represent an important advance.