Intermittent high permeability hemofiltration in septic patients with acute renal failure

A hypothesis on treatment strategy of severe multicentric Castleman disease with continuous renal replacement therapy

Castleman disease (CD) is a rare lymphoproliferative disorder, with non-specific clinical manifestations, often delayed diagnosis and treatment, which pose a significant challenge in the present times. Patients diagnosed with this disease have poor prognosis due to the limited treatment options. Multicentric CD occurs at multiple lymph node stations and is associated with a proinflammatory response that leads to the development of the so-called 'B symptoms'. IL-6 seems to be a key cytokine involved in various manifestations such as lymphadenopathies, hepatosplenomegaly, and polyclonal hypergammaglobulinemia. Its levels correlate with the activity of the disease. Other consequences of MCD include increased fibrinogen levels leading to deep vein thrombosis and thromboembolic disorders, high hepcidin levels causing anaemia, elevated VEGF levels promoting angiogenesis and vascular permeability, which, along with hypoalbuminemia, induce oedema, ascites, pleural and pericardial effusions, and in severe cases, generalized anasarca. In extreme cases multiple organ failure can occur, often resulting in death. We propose the use of continuous renal replacement therapy (CRRT) in managing severe multicentric CD. Our arguments are based on the principles that CRRT is able to remove IL-6 from circulation thus attenuating the cytokine storm, can influence hepcidin levels, and reduction in oedema, and is often used in multiple organ failure to regain homeostasis control. Therefore, it could be used as a therapy or bridge therapy in severe cases. To sustain our hypothesis with evidence, we have gathered several studies from the literature confirming the successful removal of cytokines, especially IL-6 from circulation, which can be used as a starting point.

The Techniques of Blood Purification in the Treatment of Sepsis and Other Hyperinflammatory Conditions

Even in the absence of strong indications deriving from clinical studies, the removal of mediators is increasingly used in septic shock and in other clinical conditions characterized by a hyperinflammatory response. Despite the different underlying mechanisms of action, they are collectively indicated as blood purification techniques. Their main categories include blood- and plasma processing procedures, which can run in a stand-alone mode or, more commonly, in association with a renal replacement treatment. The different techniques and principles of function, the clinical evidence derived from multiple clinical investigations, and the possible side effects are reviewed and discussed along with the persisting uncertainties about their precise role in the therapeutic armamentarium of these syndromes.

High-cutoff hemodialysis in multiple myeloma patients with acute kidney injury

Multiple myeloma (MM), an incurable hematological malignancy with clonal proliferation of plasma cells, is mainly characterized by excessive production of monoclonal immunoglobulins and free light chains (FLCs). Kidney injury is one of the main clinical manifestations and is also a significant predictor of the prognosis of symptomatic MM patients, especially those who require dialysis-supported treatment. Overproduction of FLCs is the trigger for kidney injury, as they can induce the transcription of inflammatory and profibrotic cytokines in the proximal tubule and bind to Tamm-Horsfall protein in the distal tubules to form casts that obstruct the tubules, leading to kidney injury and even renal fibrosis. In addition to traditional antimyeloma treatment, high-cutoff hemodialysis (HCO-HD), which can effectively remove FLCs in vitro, has attracted much attention in recent years. Due to its greater membrane pore size, it has significant advantages in removing larger molecules and can be applied in rhabdomyolysis, sepsis, and even myeloma cast nephropathy. However, mounting questions have recently been raised regarding whether HCO-HD can truly provide clinical benefits in MM patients with acute kidney injury (AKI). Therefore, in this study, we discussed the pathological causes of AKI secondary to MM and summarized the current situation of HCO-HD in MM patients compared with other available extracorporeal techniques. In addition, pivotal clinical trials that reflect the ability of the clearance of FLCs and the side effects of HCO-HD are highlighted, and the relevant protocol of HCO-HD is also provided to assist clinicians in decision-making.

Extrakorporale Behandlungsstrategien der Sepsis

Hintergrund Die Mortalität der Sepsis bleibt auch im 21. Jahrhundert sehr hoch. Verschiedene adjuvante Strategien zur extrakorporalen Zytokinelimination wurden als zusätzliche therapeutische Maßnahmen bei Sepsis und septischem Schock untersucht.

Ziele Zusammenfassung einer Auswahl extrakorporaler Blutreinigungstechniken und der aktuellen Erkenntnisse in der klinischen Anwendung mit besonderem Schwerpunkt auf dem therapeutischen Plasmaaustausch.

Methoden Nicht systematische Literaturrecherche.

Ergebnisse Verschiedene extrakorporale Blutreinigungstechniken mit unterschiedlichen Evidenzniveaus hinsichtlich Zytokinelimination, Verbesserung der Hämodynamik und Verringerung der Mortalität werden derzeit klinisch eingesetzt. Die am ausführlichsten untersuchten Modalitäten umfassen die hochvolumige Hämofiltration/Dialyse mit und ohne High-Cut-off-Filter sowie Hämoadsorptionstechniken (einschließlich CytoSorb- und Polymyxin-B-Filter). Trotz teilweise ermutigender Beobachtungen bezüglich der Entfernung proinflammatorischer Zytokine und verbesserten Hämodynamik zeigten randomisierte Outcome-Studien bislang keinen positiven Einfluss auf das Überleben. Aufgrund der Verwendung von Spenderplasma als Substitutionsflüssigkeit stellt der therapeutische Plasmaaustausch das einzige Verfahren dar, das neben einer reinen Elimination zusätzlich verbrauchte protektive Faktoren ersetzen kann.

Schlussfolgerungen Die Anwendung extrakorporaler Blutreinigungsmethoden kann für Sepsispatienten außerhalb klinischer Studien bisher nicht empfohlen werden, da derzeit keine Beweise für ihre Wirksamkeit vorliegen. Zukünftige Untersuchungen sollten darauf abzielen, das Patientenkollektiv hinsichtlich des klinischen Schweregrads, des Zeitpunkts der Intervention und verschiedener inflammatorischer (Sub-)Phänotypen zu homogenisieren.

Renal Replacement Techniques in Septic Shock

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to an infection; it carries a risk for mortality, considerably exceeding that of a mere infection. Sepsis is the leading cause for acute kidney injury (AKI) and the requirement for renal replacement therapy (RRT) in intensive care unit (ICU) patients. Almost every second critically ill patient with sepsis will develop AKI. In septic shock, the dysregulated host response to infectious pathogens leads to a cytokine storm with uncontrolled production and release of humoral proinflammatory mediators that evoke cellular toxicity and promote the development of organ dysfunction and increased mortality. In addition to treating AKI, RRT techniques can be employed for extracorporeal adsorption of inflammatory mediators using specifically developed adsorption membranes, hemoperfusion sorbent cartridges or columns; these techniques are intended to decrease the level and early deleterious effects of circulating proinflammatory cytokines and endotoxins during the first hours and days of septic shock treatment, in order to improve patient outcomes. Several methods and devices, such as high cut-off membranes, the Oxiris®-AN69 membrane, CytoSorb® and HA380 cytokine hemoadsorption, polymyxin B endotoxin adsorption, and plasmapheresis have been examined in small study series or are under evaluation as ways of improving patient outcomes in septic shock. However, to date, the data on actual outcome benefits have remained controversial, as discussed in this review.

The role of continuous renal replacement therapy (Crrt) in Coronavirus disease 2019 (Covid-19) patients

Even without the presence of the novel Coronavirus disease 2019 (COVID-19), acute kidney injury has been a serious problem in medicine for decades, with mortality rate up to 70% among those who eventually required renal replacement therapy, and the number has not changed significantly for the last 30 years despite major advances in technology and experience. On the other hand, even without acute kidney injury, COVID-19 was a major cause of death globally in the year 2020, but the occurrence of acute kidney injury among COVID-19 patients is an independent risk factor of increased mortality. Continuous renal replacement therapy has been recommended to treat acute kidney injury in COVID-19 patients instead of conventional intermittent hemodialysis. Moreover, its use might have another beneficial role in stopping the progression of severe COVID-19 by removing pro-inflammatory cytokines during cytokine storm syndrome, which is postulated as the pathophysiology behind severe and critically severe cases of COVID-19. This review will cover a brief history of continuous renal replacement therapy and its modalities, before digging up more into its use in COVID-19 patients, including the optimum filtration dose and timing, membrane filtration used, vascular access, anticoagulation therapy, and drug dosing adjustment during continuous renal replacement therapy.

Immune Modulation in Critically Ill Septic Patients

Sepsis is triggered by infection-induced immune alteration and may be theoretically improved by pharmacological and extracorporeal immune modulating therapies. Pharmacological immune modulation may have long lasting clinical effects, that may even worsen patient-related outcomes. On the other hand, extracorporeal immune modulation allows short-term removal of inflammatory mediators from the bloodstream. Although such therapies have been widely used in clinical practice, the role of immune modulation in critically ill septic patients remains unclear and little evidence supports the role of immune modulation in this clinical context. Accordingly, further research should be carried out by an evidence-based and personalized approach in order to improve the management of critically ill septic patients.

Blood purification for sepsis: an overview

Sepsis is a life-threatening organ failure exacerbated by a maladaptive infection response from the host, and is one of the major causes of mortality in the intensive care unit. In recent decades, several extracorporeal blood purification techniques have been developed to manage sepsis by acting on both the infectious agents themselves and the host immune response. This research aims to summarize recent progress on extracorporeal blood purification technologies applied for sepsis, discuss unanswered questions on renal replacement therapy for septic patients, and present a decision-making strategy for practitioners.

Clearance of inflammatory cytokines in patients with septic acute kidney injury during renal replacement therapy using the EMiC2 filter (Clic-AKI study)

BACKGROUND

The EMiC2 membrane is a medium cut-off haemofilter (45 kiloDalton). Little is known regarding its efficacy in eliminating medium-sized cytokines in sepsis. This study aimed to explore the effects of continuous veno-venous haemodialysis (CVVHD) using the EMiC2 filter on cytokine clearance.

METHODS

This was a prospective observational study conducted in critically ill patients with sepsis and acute kidney injury requiring kidney replacement therapy. We measured concentrations of 12 cytokines [Interleukin (IL) IL-1β, IL-1α, IL-2, IL-4, IL-6, IL-8, IL-10, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, vascular endothelial growth factor, monocyte chemoattractant protein (MCP)-1, epidermal growth factor (EGF)] in plasma at baseline (T0) and pre- and post-dialyzer at 1, 6, 24, and 48 h after CVVHD initiation and in the effluent fluid at corresponding time points. Outcomes were the effluent and adsorptive clearance rates, mass balances, and changes in serial serum concentrations.

RESULTS

Twelve patients were included in the final analysis. All cytokines except EGF concentrations declined over 48 h (p < 0.001). The effluent clearance rates were variable and ranged from negligible values for IL-2, IFN-γ, IL-1α, IL-1β, and EGF, to 19.0 ml/min for TNF-α. Negative or minimal adsorption was observed. The effluent and adsorptive clearance rates remained steady over time. The percentage of cytokine removal was low for most cytokines throughout the 48-h period.

CONCLUSION

EMiC2-CVVHD achieved modest removal of most cytokines and demonstrated small to no adsorptive capacity despite a decline in plasma cytokine concentrations. This suggests that changes in plasma cytokine concentrations may not be solely influenced by extracorporeal removal.

TRIAL REGISTRATION

NCT03231748, registered on 27th July 2017.

Severe acute kidney injury in COVID-19 patients is associated with in-hospital mortality

Although the lungs are major targets for COVID-19 invasion, other organs-such as the kidneys-are also affected. However, the renal complications of COVID-19 are not yet well explored. This study aimed to identify the incidence of acute kidney injury (AKI) in patients with COVID-19 and to evaluate its impact on patient outcomes. This retrospective study included 704 patients with COVID-19 who were hospitalized at two hospitals in Daegu, Korea from February 19 to March 31, 2020. AKI was defined according to the serum creatinine criteria in the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. The final date of follow-up was May 1, 2020. Of the 704 patients, 28 (4.0%) developed AKI. Of the 28 patients with AKI, 15 (53.6%) were found to have AKI stage 1, 3 (10.7%) had AKI stage 2, and 10 (35.7%) had AKI stage 3. Among these patients, 12 (42.9%) recovered from AKI. In the patients with AKI, the rates of admission to intensive care unit (ICU), administration of mechanical ventilator (MV), and in-hospital mortality were significantly higher than in patients without AKI. Multivariable analysis revealed that old age (Hazard ratio [HR] = 4.668, 95% confidence interval [CI] = 1.250-17.430, p = 0.022), high neutrophil-to-lymphocyte ratio (HR = 1.167, 95% CI = 1.078-1.264, p < 0.001), elevated creatinine kinase (HR = 1.002, 95% CI = 1.001-1.004, p = 0.007), and severe AKI (HR = 12.199, 95% CI = 4.235-35.141, p < 0.001) were independent risk factors for in-hospital mortality. The Kaplan-Meier curves showed that the cumulative survival rate was lowest in the AKI stage 3 group (p < 0.001). In conclusion, the incidence of AKI in patients with COVID-19 was 4.0%. Severe AKI was associated with in-hospital death.

Is there a role for blood purification therapies targeting cytokine storm syndrome in critically severe COVID-19 patients?

The coronavirus disease-19 (COVID-19) has spread over many countries and regions since the end of 2019, becoming the most severe public health event at present. Most of the critical cases developed multiple organ dysfunction, including acute kidney injury (AKI). Cytokine storm syndrome (CSS) may complicate the process of severe COVID-19 patients. This manuscript reviews the different aspects of blood purification in critically ill patients with AKI and increased inflammatory factors, and examines its potential role in severe COVID-19 treatment. Continuous renal replacement therapy (CRRT) has been practiced in many sepsis patients with AKI. Still, the timing and dosing need further robust evidence. In addition to the traditional CRRT, the high-throughput membrane with adsorption function and cytokine adsorption column are two representatives of recently emerging novel membrane technologies. Their potential in removing inflammatory factors and other toxins prospects for the treatment of severe COVID-19.

[Extracorporeal techniques for blood purification in sepsis: an update]

BACKGROUND

Despite ongoing development, mortality in sepsis remains considerable. Various techniques for extracorporeal cytokine removal have been described, but evidence remains conflicting.

OBJECTIVES

The aim of this article is to summarize currently used extracorporeal blood purification techniques and their evidence.

METHODS

Non-systematic literature review RESULTS: There are currently various blood purification techniques used with different levels of evidence regarding cytokine removal, vasopressor sparing effects and reduction of mortality, including high-volume dialysis with and without high cut-off filters, special adsorption filters (including CytoSorb®, CytoSorbents Europe, Berlin, Germany, and polymyxin‑B filters). There is development regarding therapeutic plasma exchange. For some blood purification techniques such as combined plasma filtration and adsorption, multicentric randomized studies found a negative effect on survival.

CONCLUSIONS

Despite a theoretical rationale, the use of blood purification methods cannot be recommended for sepsis patients due to the lack of evidence of their efficacy. Heterogeneous inflammatory responses in sepsis render conduction of larger trials difficult. Thus, future studies should cautiously identify appropriate sepsis subtypes to be included. Available techniques should be chosen as individualized complementary treatments and not as competing systems.

Blood Purification Techniques for Sepsis and Septic AKI

Sepsis is the primary cause of acute kidney injury in critically ill patients. During the past decades, several extracorporeal blood purification techniques have been developed for sepsis and sepsis-induced acute kidney injury management. These therapies could act on both the infectious agent itself and the host immune response. In this article, we review the available literature discussing the different extracorporeal blood purification techniques, including high-volume hemofiltration, cascade hemofiltration, hemoperfusion, coupled plasma filtration adsorption, plasma exchange, and specific optimized renal replacement therapy membranes.

A Double-Blind Randomized Controlled Trial of High Cutoff Versus Standard Hemofiltration in Critically Ill Patients With Acute Kidney Injury

OBJECTIVES

In critically ill patients with acute kidney injury receiving vasopressors, high cytokine levels may sustain the shock state. High cutoff hemofiltration achieves greater cytokine removal in ex vivo and in animal models and may reduce the duration of shock but may also increase albumin losses.

DESIGN

This was a single-center double-blind randomized controlled trial comparing continuous venovenous hemofiltration-high cutoff to continuous venovenous hemofiltration-standard.

SETTING

Tertiary care hospital in Australia.

PATIENTS

Vasopressor-dependent patients in acute kidney injury who were admitted to the ICU.

INTERVENTIONS

Norepinephrine-free time were calculated in critically ill vasopressor-dependent patients in acute kidney injury, randomized to either continuous venovenous hemofiltration-high cutoff or continuous venovenous hemofiltration-standard.

MEASUREMENT AND MAIN RESULTS

A total of 76 patients were randomized with the following characteristics (continuous venovenous hemofiltration-high cutoff vs continuous venovenous hemofiltration-standard); median age of 65 versus 70 year, percentage of males 47% versus 68%, and median Acute Physiology and Chronic Health Evaluation scores of 25 versus 23.5. The median hours of norepinephrine-free time at day 7 were 32 (0-110.8) for continuous venovenous hemofiltration-high cutoff and 56 hours (0-109.3 hr) (p = 0.520) for continuous venovenous hemofiltration-standard. Inhospital mortality was 55.6% with continuous venovenous hemofiltration-high cutoff versus 34.2% with continuous venovenous hemofiltration-standard (adjusted odds ratio, 2.49; 95% CI, 0.81-7.66; p = 0.191). There was no significant difference in time to cessation of norepinephrine (p = 0.358), time to cessation of hemofiltration (p = 0.563), and filter life (p = 0.21). Serum albumin levels (p = 0.192) were similar and the median dose of IV albumin given was 90 grams (20-212 g) for continuous venovenous hemofiltration-high cutoff and 80 grams (15-132 g) for continuous venovenous hemofiltration-standard (p = 0.252).

CONCLUSIONS

In critically ill patients with acute kidney injury, continuous venovenous hemofiltration-high cutoff did not reduce the duration of vasopressor support or mortality or change albumin levels compared with continuous venovenous hemofiltration-standard.

Albumin handling in different hemodialysis modalities

Hypoalbuminemia is a major risk factor for morbidity and mortality in dialysis patients. With increasing interest in highly permeable membranes and convective therapies to improve removal of middle molecules, transmembrane albumin loss increases accordingly. Currently, the acceptable upper limit of albumin loss for extracorporeal renal replacement therapies is unknown. In theory, any additional albumin loss should be minimized because it may contribute to hypoalbuminemia and adversely affect the patient's prognosis. However, hypoalbuminemia-associated mortality may be a consequence of inflammation and malnutrition, rather than low albumin levels per se. The purpose of this review is to give an overview of albumin handling with different extracorporeal renal replacement strategies. We conclude that the acceptable upper limit of dialysis-related albumin loss remains unknown. Whether enhanced middle molecule removal outweighs the potential adverse effects of increased albumin loss with novel highly permeable membranes and convective therapies is yet to be determined.

Early continuous renal replacement therapy during infant extracorporeal life support is associated with decreased lung opacification

Lung opacification on chest radiography (CXR) is common during extracorporeal life support (ECLS), often resulting from pulmonary edema or inflammation. Concurrent use of continuous renal replacement therapy (CRRT) during ECLS is associated with improved fluid balance and cytokine filtration; through modification of these pathologic states, CRRT may modulate lung opacification observed on CXRs. We hypothesize that early CRRT use during infant ECLS decreases lung opacification on CXR. We conducted a retrospective cohort study comparing CXRs from infants receiving ECLS and early CRRT (n = 7) to matched infants who received ECLS alone (n = 7). The CXR obtained prior to ECLS, all CXRs obtained within the first 72 h of ECLS, and daily CXRs for the remainder of the ECLS course were analyzed. The outcome measure was the degree of opacification, determined by independent assessment of two, blinded pediatric radiologists using a modified Edwards et al.'s lung opacification scoring system (from Score 0: no opacification to Score 5: complete opacification). 220 CXRs were assessed (cases: 93, controls: 127). Inter-rater reliability was established (Cohen's weighted к = 0.74; p < 0.0001, good agreement). At baseline, the mean opacification score difference between cases and controls was 1 point (cases: 1.8, controls 2.8; p = 0.049). Using mixed modeling analysis for repeated measures accounting for differences at baseline, the average overall opacification score was 1.2 points lower in cases than controls (cases: 2.1, controls: 3.3; p < 0.0001). The overall distribution of scores was lower in cases than controls. Early CRRT utilization during infant ECLS was associated with decreased lung opacification on CXR.

Acute kidney injury from sepsis: current concepts, epidemiology, pathophysiology, prevention and treatment

Sepsis-associated acute kidney injury (S-AKI) is a frequent complication of the critically ill patient and is associated with unacceptable morbidity and mortality. Prevention of S-AKI is difficult because by the time patients seek medical attention, most have already developed acute kidney injury. Thus, early recognition is crucial to provide supportive treatment and limit further insults. Current diagnostic criteria for acute kidney injury has limited early detection; however, novel biomarkers of kidney stress and damage have been recently validated for risk prediction and early diagnosis of acute kidney injury in the setting of sepsis. Recent evidence shows that microvascular dysfunction, inflammation, and metabolic reprogramming are 3 fundamental mechanisms that may play a role in the development of S-AKI. However, more mechanistic studies are needed to better understand the convoluted pathophysiology of S-AKI and to translate these findings into potential treatment strategies and add to the promising pharmacologic approaches being developed and tested in clinical trials.

Middle molecule clearance with high cut-off dialyzer versus high-flux dialyzer using continuous veno-venous hemodialysis with regional citrate anticoagulation: A prospective randomized controlled trial

BACKGROUND

Regional anticoagulation with citrate during renal replacement therapy (RRT) reduces the risk of bleeding, extends dialyzer lifespan and is cost-effective. Therefore, current guidelines recommend its use if patients are not anticoagulated for another reason and if there are no contraindications against citrate. RRT with regional citrate anticoagulation has been established in critically ill patients as continuous veno-venous hemodialysis (CVVHD) to reduce citrate load. However, CVVHD is inferior regarding middle molecule clearance compared to continuous veno-venous hemofiltration (CVVH). The use of a high cut-off dialyzer in CVVHD may thus present an option for middle molecule clearance similar to CVVH. This may allow combining the advantages of both techniques.

METHODS

In this prospective, randomized, single-blinded single-center-trial, sixty patients with acute renal failure and established indication for renal replacement therapy were randomized 1:1 into two groups. The control group was put on CVVHD using regional citrate anticoagulation and a high-flux dialyzer, while the intervention group was on CVVHD using regional citrate anticoagulation and a high-cut-off dialyzer. The concentrations of urea, creatinine, β2-microglobulin, myoglobin, interleukin 6 and albumin were measured pre- and post-dialyzer 1, 6, 12, 24 and 48 hours after initiating CVVHD.

RESULTS

Mean plasma clearance for β2-microglobulin was 19.6±5.8 ml/min in the intervention group vs. 12.2±3.6 ml/min in the control group (p<0.001). For myoglobin (8.0±4.5 ml/min vs. 0.2±3.6 ml/min, p<0.001) and IL-6 (1.5±4.3 vs. -2.5±3.5 ml/min, p = 0.002) a higher mean plasma clearance using high-cut-off dialyzer could be detected too, but no difference for urea, creatinine and albumin could be observed concerning this parameter between the two groups.

CONCLUSION

CVVHD using a high cut-off dialyzer results in more effective middle molecule clearance than that with high-flux dialyzer.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS00005254, registered 26th November 2013).

Hemodynamic efficiency of hemodialysis treatment with high cut-off membrane during the early period of post-resuscitation shock: The HYPERDIA trial

BACKGROUND

After resuscitation of cardiac arrest (CA), an acute circulatory failure occurs in about 50% of cases, which shares many characteristics with septic shock. Most frequently, supportive treatments are poorly efficient to prevent multiple organ failure and death. We evaluated whether an early plasma removal of inflammatory mediators using high cut-off continuous veno-venous hemodialysis (HCO-CVVHD) could improve hemodynamic status and outcome of these patients.

PATIENTS AND METHODS

We performed a randomized open-label trial. Patients with post-cardiac arrest shock (defined as requirement of norepinephrine or epinephrine infusion > 1 mg/h) were included. The experimental group received 2 distinct sessions of HCO-CVVHD during the first 48 h following ICU admission. The control group received continuous veno-venous hemofiltration (CVVH) with standard membranes if needed. The primary endpoint was the delay to shock resolution asssessed by the length of catecholamine infusion. Number of vasopressors-free days at day 28, arterial blood pressure measures every 6-hours, daily fluid balance and mortality (ICU and day-28) were evaluated as secondary endpoints.

RESULTS

35 patients were included: 17 (median age 68.4, 59% male) in the HCO-CVVHD group and 18 (median age 66.3, 83% male) in the control group. Baseline characteristics did not differ between the two groups. Day-28 mortality rate was 64.7% and 72.2% in the HCO-CVVHD and control group, respectively (p = 0.72). Probability of vasopressors discontinuation over time was similar in the two groups (p for logrank test = 0.67). Number of day-28 catecholamine-free days was 25.1 [0, 26.5] and 24.5 [0, 26.2] in the HCO-CVVHD and control group, respectively (p = 0.65). No difference was observed regarding the daily-dose of vasopressors, arterial pressure profile and fluid balance.

CONCLUSION

In cardiac arrest patients, HCO-CVVHD did not decrease the lenght of post-resuscitation shock and had no significant effect on hemodynamic profile.

REGISTRATION

NCT00780299.

High Efficiency Removal of Cytokines and HMGB-1 by Continuous Hemofiltration With a Dual Layered Polyethersulfone Membrane: An Ex Vivo Study

Cytokines and high mobility group box chromosomal protein-1 (HMGB-1) play key roles in inflammatory conditions. While hemofiltration has been shown to remove cytokines, removal of cytokines and HMGB-1 by hemofiltration using a polyethersulfone membrane has not been reported. This study aimed to test the hypothesis that the polyethersulfone membrane will achieve higher removal performance for substances including inflammatory cytokines compared to other hemofilters, while retaining low albumin removal capacity. Subjects were eight healthy volunteers. We collected 400 mL each of blood samples into containers with heparin and added 30 mg of lipopolysaccharide to spike cytokines and HMGB-1. After incubation at 39ºC for 12 h, each blood sample was circulated through a hemofiltration circuit with a polyethersulfone hemofilter (2.1 m² or 1.1 m² ) at a filtration flow rate of 2 L/h. Measurement samples were collected from arterial, venous, and ultrafiltrate sampling points. Concentrations of cytokines (IL-1ß, IL-4, IL-6, IL-8, IL- 10, and tumor necrosis factor [TNF-a]), HMGB-1, and albumin were determined at each time point (1, 4, 8, 12, and 24h). High sieving coefficients (SCs) above 0.8 were obtained for all cytokines except for TNF-a as well as HMGB-1, whereas the SC for albumin was less than 0.04 with both hemofilters. The hemofilter with a larger membrane area achieved significantly higher clearances for TNF-a and HMGB-1, and slower decreases in SCs over time for IL-1ß, IL-6, IL-8, TNF-a, and albumin. Continuous hemofiltration with a polyethersulfone membrane achieved high efficiency removal of cytokines and HMGB-1, without excessive removal of albumin.

Extracorporeal techniques for the treatment of critically ill patients with sepsis beyond conventional blood purification therapy: the promises and the pitfalls

Sepsis is one of the leading causes of morbidity and mortality worldwide. It is characterized by a dysregulated immune response to infections that results in life-threatening organ dysfunction and even death. Bacterial cell wall components (endotoxin or lipopolysaccharide), known as pathogen-associated molecular patterns (PAMPs), as well as damage-associated molecular patterns (DAMPs) released by host injured cells, are well-recognized triggers resulting in the elevation of both pro-inflammatory and anti-inflammatory cytokines. Understanding this complex pathophysiology has led to the development of therapeutic strategies aimed at restoring a balanced immune response by eliminating/deactivating these inflammatory mediators. Different extracorporeal techniques have been studied in recent years in the hope of maximizing the effect of renal replacement therapy in modulating the exaggerated host inflammatory response, including the use of high volume hemofiltration (HVHF), high cut-off (HCO) membranes, adsorption alone, and coupled plasma filtration adsorption (CPFA). These strategies are not widely utilized in practice, depending on resources and local expertise. The literature examining their use in septic patients is growing, but the evidence to support their use at this stage is considered of low level. Our aim is to provide a comprehensive overview of the technical aspects, clinical applications, and associated side effects of these techniques.

Confirmation of High Cytokine Clearance by Hemofiltration with a Cellulose Triacetate Membrane with Large Pores: An in vivo Study

Objective

To confirm in vivo the hypothesis that hemofiltration with a large pore membrane can achieve significant cytokine clearance.

Method

We used a well-known animal model of endotoxinic shock (0.5 mg/kg of lipopolysaccharide from Escherichia Coli over a period of 30 mins). Six pigs were hemofiltrated for 3 hours with a large pore membrane (78 Å pore, 80 kDa cut off) (Sureflux FH 70, Nipro, Osaka, Japan). The ultrafiltration rate was 45 ml/kg/min. Samples were taken from arterial, venous line and in the ultrafiltrate at T120 and T240. We measured concentrations of interleukin 6, interleukin 10 and albumin.

Results

At T120 and T240, the IL-6 clearances were 22 ± 7 and 15 ± 3 ml/min, respectively. The IL-6 sieving coefficients were 0.97 and 0.7 at T120 and T240, respectively. At T120 and T240, the IL-10 clearances were 14 ± 4 and 10 ± 7 ml/min, respectively. The sieving coefficients were 0.63 and 0.45 at T120 and T240, respectively. The concentrations of IL-6 and IL-10 were the same at T0 and T240. At T60 and T240, the plasmatic albumin concentrations were 24 ± 4 g/L and 23 ± 4 g/L, respectively (p = 0.13).

Conclusions

In this animal model of endotoxinic shock, we confirm the high cytokine clearance observed when hemofiltration is applied to a large pore membrane. The loss of albumin seems negligible. The impact of such clearances on hemodynamic stability and survival remains to be proved.

High Cut-off Point Membranes in Septic Acute Renal Failure: A Systematic Review

Objectives

To review the literature on the experimental, physiological and clinical effects of blood purification with high cut-off (HCO) point membranes in septic acute renal failure (ARF).

Study Design

MEDLINE and PubMed database search combining relevant terms and integrating data from studies on the use of HCO membranes.

Setting and Population

Ex vivo studies of endotoxemia, animal studies of bacteremia and clinical studies using HCO membranes in patients with septic ARF. Selection Criteria for Studies: Original data from primary publications. Interventions: HCO membrane-based hemodialysis, hemodiafiltration or hemofiltration. Outcomes: Plasma cytokine clearance, immunological and physiological effects and safety parameters of HCO membranes.

Results

HCO membranes effectively remove cytokines from blood. Treatment using HCO membranes has beneficial effects on immune cell function and increases survival in animal models of sepsis. Preliminary clinical studies show that HCO membranes decrease plasma cytokine levels and the need for vasopressor therapy. HCO membrane-based blood purification has now been applied in four pilot randomized controlled studies of 70 patients with septic ARF with no reports of serious adverse effects.

Limitations

Because of substantial heterogeneity, no formal quantitative analysis could be performed.

Conclusions

The available evidence on HCO blood purification justifies larger randomized controlled trials in patients with septic ARF.

Treatment of Acute Kidney Injury Complicating Septic Shock with EMiC2 High-cutoff Hemofilter: Case Series

Introduction:

Extracorporeal blood purification therapies have been proposed to improve outcomes of patients with severe sepsis, with or without accompanying acute kidney injury (AKI), by removal of excessive inflammatory mediators.

Materials and Methods:

We report our experience with EMiC2 high-cutoff continuous venovenous hemofiltration/hemodialysis (HCO-CVVH/HD) in seven patients with AKI complicating septic shock.

Results:

The median treatment duration was 71 h, and the procedure was well tolerated. Trough serum albumin level of 20 g/L was observed after 2 h of treatment and none of the patients required albumin supplement. The hospital mortality rate was 29%, which appeared more favorable than the predicted mortality of 60%–78% based on disease severity scores. Circulating levels of interleukin-6 (IL-6), IL-10, and tumor necrosis factor-alpha improved over time.

Conclusion:

This case series shows that HCO-CVVH/CVVHD using EMiC2 hemofilter may provide good cytokine modulation, when used along with good quality standard sepsis therapy. A further large-scale prospective randomized controlled trial is recommended.

High Cut-off Membranes in Acute Kidney Injury and Continuous Renal Replacement Therapy

Innovation in continuous renal replacement therapies (CRRT) utilized to treat acute kidney injury (AKI) and sepsis, has brought new machines and techniques. Part of these new advances are due to the availability of innovative biomaterials and the construction of membranes with larger pores and wide distribution of pore sizes. This includes the creation of a new generation of high cut-off membranes whose utilization in clinical practice is promising for the wide spectrum of solutes that are removed during extracorporeal therapies.

However, the enlargement of pore diameters brings some loss of albumin during treatment and this effect is still under evaluation, since there is a possibility that this is detrimental for the patient. A thorough review of the available clinical literature is reported in this paper with a reappraisal of the potential application of these new technologies.

Clearance of Selected Plasma Cytokines with Continuous Veno-Venous Hemodialysis Using Ultraflux EMiC2 versus Ultraflux AV1000S

BACKGROUND

High cutoff hemofilters might support the restoration of immune homeostasis in systemic inflammation by depleting inflammatory mediators from the circulation.

METHODS

Interleukin (IL)-6, IL-8, IL-10, and tumor necrosis factor-alpha depletion was assessed in 30 sepsis patients with acute renal failure using continuous veno-venous hemodialysis with high cutoff versus standard filters (CVVHD-HCO vs. CVVHD-STD) over 48 h.

RESULTS

The transfer of IL-6 and IL-8 was significantly higher for CVVHD-HCO, as shown by increased IL-6 and IL-8 effluent concentrations. The mean plasma cytokine concentrations decreased over time for all cytokines without detectable differences for the treatment modalities. No transfer of albumin was observed for either of the filters. C-reactive protein remained stable over time and did not differ between CVVHD-HCO and CVVHD-STD, while procalcitonin decreased significantly over 48 h for both treatment modalities.

CONCLUSION

CVVHD-HCO achieved enhanced removal of IL-6 and IL-8 as compared to CVVHD-STD, without differentially reducing plasma cytokine levels.

High cut-off hemofiltration versus standard hemofiltration: effect on plasma cytokines

PURPOSE

To study the effects of continuous veno-venous hemofiltration (CVVH) with high cut-off filters (CVVH-HCO) on plasma cytokine levels, sieving coefficient and clearance compared to CVVH using standard filters (CVVH-Std) in a nested cohort within a double-blind randomized controlled trial in severe acute kidney injury (AKI) patients.

METHODS

We measured plasma and post-filter levels of IL-6, TNF-alpha, IL-8, IL-1 beta, RANTES, IL-10, IFN-gamma and IFN-alpha in both study groups. We also measured cytokine levels in the ultrafiltrate and calculated sieving coefficients and clearances.

RESULTS

By 72 hours of treatment, IL-6 had decreased during both treatments (p = 0.009 and 0.005 respectively). In contrast, IL-10 had decreased with CVVH-Std (p = 0.03) but not CVVH-HCO (p = 0.135). None of the other cytokines showed changes over time. There were also no significant between group differences in plasma levels for each cytokine over the 72-hour treatment period. For all cytokines combined, however, the median sieving coefficient was higher for CVVH-HCO (0.31 vs. 0.16; p = 0.042) as was the mass removal rate by ultrafiltration (p = 0.027). While overall combined cytokine levels had fallen to 62.2% of baseline at 72 hours for CVVH-HCO (p&lt;0.0001) and to 75.9% of baseline with CVVH-Std (p = 0.008) there were no between group differences.

CONCLUSIONS

CVVH-HCO achieved greater combined sieving coefficient and mass removal rate by ultrafiltration for a group of key cytokines than CVVH-Std. However, this effect did not differentially lower their plasma level over the first 72 hours. Our study does not support the use of CVVH-HCO to lower cytokines in critically ill patients with AKI.

High cutoff membrane to reduce systemic inflammation due to differentiation syndrome: a case report

BACKGROUND

Differentiation syndrome is a life-threatening complication of therapy that is carried out with agents used for acute promyelocytic leukemia. Its physiopathology comprehends the production of inflammatory mediators by differentiating granulocytes, endothelial and alveolar cells due to stimulation by all-trans retinoic acid and leading to sustained systemic inflammation.

METHODS

Treatment with high cut-off continuous veno-venous hemodialysis (HCO-CVVHD) was performed to reduce the circulating mediators of systemic inflammation.

RESULTS

After 52 h of treatment, an important reduction was observed in inflammatory mediators (IL-1β: from 10 to 2 pg/ml; IL-8: from 57 to 40 pg/ml; TNF-α: from 200 to 105 pg/ml; IL-6: from 263 to 91 pg/ml), as well as in anti-inflammatory mediators (IL-10: from 349 to 216 pg/ml).

CONCLUSIONS

HCO-CVVHD should be explored as a part of treatment in systemic inflammation states other than sepsis (e.g., differentiation syndrome). Furthermore, its immunomodulatory effects could be particularly useful in immunocompromised patient treated with corticosteroids.

Cytokine removal with high cut-off membrane: review of literature

During the last decade, blood purification therapies have been proposed as an effective therapy to control the cytokines dysregulation in systemic inflammatory syndromes. Among them, the treatment with high cut-off membranes is characterized by larger pore size and more effective clearance for middle molecular weight molecules (cytokines). In this paper, we performed a thoughtful review of the literature on HCO being used for blood purification indications in all systemic inflammation syndromes. Clinical and experimental studies show that the use of high effluent flows in a pure diffusive treatment effectively removes serum cytokines with a safe profile in albumin clearance. In clinical studies, the removal of these inflammatory mediators is associated with a significant improvement in hemodynamic condition, oxygenation indices, and organ dysfunction.

High cut-off hemofiltration versus standard hemofiltration: a pilot assessment of effects on indices of apoptosis

OBJECTIVES

To measure plasma pro-apoptotic and pro-necrotic activity in severe acute kidney injury (AKI) patients within a randomized controlled trial of continuous veno-venous hemofiltration with high cut-off filters (CVVH-HCO) versus standard filters (CVVH-Std).

METHODS

We measured pro-apoptotic and pro-necrotic plasma activity by trypan blue exclusion cell viability assay, detection of DNA fragmentation, and by determination of caspase-3 activity and annexin V-based apoptosis and necrosis detection assay.

RESULTS

Compared to no apoptosis or necrosis after incubation with healthy plasma, 14-18% of cells showed apoptosis and 4-8% showed necrosis after incubation with plasma from AKI patients. When comparing different measures of pro-apoptotic or pro-necrotic activity, CVVH-HCO and CVVH-Std showed no differential effects on such activity, which remained high over the first 3 days of treatment. However, using annexin V-FITC, there was a significant drop in pro-apoptotic activity across the filter for the CVVH-HCO group (p = 0.043) but not for the CVVH-Std group (p = 0.327) and a significant difference between the two groups (CVVH-HCO vs. CVVH-Std p = 0.006).

CONCLUSIONS

Patients with severe AKI have increased pro-apoptotic and pro-necrotic activity. Although on single-pass effect assessment, CVVH-HCO was superior to CVVH-Std in decreasing annexin V-FITC-assessed pro-apoptotic activity, there was no overall attenuation of such activity during the first 3 days of treatment.

Techniques of extracorporeal cytokine removal: a systematic review of human studies

BACKGROUND AND AIMS

Hypercytokinemia is believed to be harmful and reducing cytokine levels is considered beneficial. Extracorporeal blood purification (EBP) techniques have been studied for the purpose of cytokine reduction. We aimed to study the efficacy of various EBP techniques for cytokine removal as defined by technical measures.

METHOD

We conducted a systematic search for human clinical trials which focused on technical measures of cytokine removal by EBP techniques. We identified 41 articles and analyzed cytokine removal according to clearance (CL), sieving coefficient (SC), ultrafiltrate (UF) concentration and percentage removed.

RESULTS

We identified the following techniques for cytokine removal: standard hemofiltration, high volume hemofiltration (HVHF), high cut-off (HCO) hemofiltration, plasma filtration techniques, and adsorption techniques, ultrafiltration (UF) techniques relating to cardiopulmonary bypass (CPB), extracorporeal liver support systems and hybrid techniques including combined plasma filtration adsorption. Standard filtration techniques and UF techniques during CPB were generally poor at removing cytokines (median CL for interleukin 6 [IL-6]: 1.09 mL/min, TNF-alpha 0.74 mL/min). High cut-off techniques consistently offered moderate cytokine removal (median CL for IL-6: 26.5 mL/min, interleukin 1 receptor antagonist [IL-1RA]: 40.2 mL/min). Plasma filtration and extracorporeal liver support appear promising but data are few. Only one paper studied combined plasma filtration and adsorption and found low rates of removal. The clinical significance of the cytokine removal achieved with more efficacious techniques is unknown.

CONCLUSION

Human clinical trials indicate that high cut-off hemofiltration techniques, and perhaps plasma filtration and extracorporeal liver support techniques are likely more efficient in removing cytokines than standard techniques.

First level prevention instead of third level intervention-review of research to improve biocompatibility and performance of capillary membrane apheresis in critically ill patients

In intensive care medicine, convection-based apheresis is of growing interest. Applying extracorporeal systems in the critically ill patient can cause severe complications like nosocomial infections and bleeding, which can be worsened or even initialized by the anticoagulation protocol used. Furthermore, the filter modules (hemo- and plasmafilters) often tend to a fast blockage. A decrease in sieving performance due to membrane fouling may be tolerable for some time, but the complete blockage of high percentages of hollow fibers, which is named "clotting," often requires the immediate exchange of the filter. Extracorporeal detoxification and high clearance renal replacement regimes both require high blood flow and filtration rates. As a consequence, filter clotting and anticoagulation-associated bleeding are the most sensitive aspects in these applications. We were interested in the paradox phenomenon of the parallel occurrence of intra vitam bleeding and filter clotting in critically ill patients. Through stepwise investigations based on in vitro and animal experiments, we identified a stasis of blood flow followed by blood cell sedimentation and aggregation ("clogging") as the main factor of hollow fiber blockage in hemo- and plasma filters. As a result, various aspects which increase the risk of stasis inside the hollow fibers were investigated, for example, patient's hemorheology, configuration of an extracorporeal treatment system including interaction of catheter features with the filtration procedure, and basic therapeutic approaches such as colloidal volume substitutes and tolerated acidosis. Finally, an etiological triad for the blockage of hollow fibers due to filter clogging and consecutive filter failure was formed.

Novel renal replacement strategies for the elimination of serum free light chains in patients with kappa light chain nephropathy

Multiple myeloma (MM) is a malignancy with excessive production of monoclonal proteins. At disease presentation 30% of MM patients have significant renal impairment which may progress to renal failure requiring dialysis. Besides chemotherapy extracorporeal elimination procedures such as plasma exchange have been applied as adjuvant strategies to eliminate free light chains from circulating blood, however the efficacy was poor with older techniques. We report about a highly efficient method to eliminate serum free light chain (sFLC) using a newly designed protein leaking membrane in patients suffering from sFLC induced acute renal failure. The protein leaking membrane (HCO 1100) is characterized by increased pore size facilitating elimination of middle molecules such as sFLC kappa (22.5 kD). The HCO 1100 membrane was applied in a hemodialysis and hemodiafiltration mode and compared to standard procedures (high flux hemodialysis, hemodiafiltration and plasma exchange). Hemodiafiltration with the protein leaking membrane HCO 1100 was superior to all other extracorporeal replacement strategies in eliminating sFLC-kappa from circulating blood. A median blood reduction rate of 40.8% (range 13.9% - 66.4%) was achieved during hemodiafiltration. The corresponding peak clearance rate was 25 ml/min. Importantly, the poorest elimination rate was achieved by plasma exchange followed by standard high flux hemodialysis. Extracorporeal elimination strategies with the protein leaking membrane HCO 1100 may be a promising adjuvant treatment strategy for patients with sFLC nephropathy requiring dialysis. Hemodiafiltration and to lesser extend also hemodialysis with the HCO 1100 hemofilter are able to eliminate substantial amounts of sFLC kappa in MM patients.

Removal of 17 cytokines, HMGB1, and albumin by continuous hemofiltration using a cellulose triacetate membrane: an ex vivo study

BACKGROUND

Hemofiltration is often used to treat critically ill patients with renal failure and septic shock. Although hemofiltration has been reported to remove humoral mediators such as cytokines, most studies have investigated the removal of only limited kinds of cytokines. Here, we assessed the removal of 17 cytokines, HMGB1, and albumin by continuous hemofiltration (CHF) with a cellulose triacetate membrane (2.1 m(2) or 1.1 m(2)).

METHODS

The subjects were six healthy volunteers. We collected 400 mL blood into containers with heparin. After adding 1 mg/mL lipopolysaccharide, the blood was incubated at 39°C for 12 h and then filtered through a closed hemofiltration circuit (1 or 2 L/h). Sixty and 240 min after beginning hemofiltration, samples were collected from the outlet (arterial) side, inlet (venous) side, and filtrate port. Blood levels of cytokines, HMGB1, and albumin were determined at each time point.

RESULTS

Increasing the flow rate significantly increased cytokine clearance. Increasing the membrane area of the hemofilter significantly changed the sieving coefficient of only five cytokines (IL-1β, IL-6, MCP-1, MIP-1β, HMGB1). For many cytokines, the sieving coefficient did not decline during the 240-min CHF procedure.

CONCLUSION

Although all 17 cytokines, HMGB1, and albumin were detected in the filtrate, the SC and clearance varied widely. For numerous cytokines, clearance increased with the higher filtration flow rate. We demonstrated that CHF removed many cytokines and HMGB1, but was inefficient at removing albumin.

High cut-off dialysis membranes: current uses and future potential

The removal of larger uremic toxins by conventional dialysis membranes is restricted by their molecular weight cut-offs. The recent availability of a new generation of hemodialysis membranes with molecular weight cut-offs closer to that of the native kidney (65 kDa) has led to work assessing their potential utility across several different clinical scenarios. Initially designed to remove proinflammatory cytokines in patients with severe sepsis syndrome, clinicians are now using these membranes for the treatment of myeloma kidney and rhabdomyolysis. Further early pilot studies have demonstrated a potential utility for the removal of larger middle molecules in the population with end-stage renal failure. The purpose of this review was to summarize the current evidence base for the use of high cut-off hemodialysis membranes and discuss their future clinical relevance.

Review article: Renal support in critical illness

PURPOSE

This review provides a focused and comprehensive update on established and emerging evidence in acute renal replacement therapy (RRT) for critically ill patients with acute kidney injury (AKI).

PRINCIPAL FINDINGS

There have been considerable technological innovations in the methods and techniques for provision of extracorporeal RRT in critical illness. These have greatly expanded our capability to provide both renal and non-renal life-sustaining organ support for critically ill patients. Recent data suggest earlier initiation of RRT in AKI may confer an advantage for survival and renal recovery. Two large trials have recently shown no added benefit to augmented RRT dose delivery in AKI. Observational data have also suggested that fluid accumulation in critically ill patients with AKI is associated with worse clinical outcome. However, several fundamental clinical questions remain to be answered, including issues regarding the time to ideally initiate/discontinue RRT, the role of high-volume hemofiltration or other blood purification techniques in sepsis, and extracorporeal support for combined liver-kidney failure. Extracorporeal support with RRT in sepsis, rhabdomyolysis, and liver failure are discussed, along with strategies for drug dosing and management of RRT in sodium disorders.

CONCLUSIONS

We anticipate that this field will continue to expand to promote research and innovation, hopefully for the benefit of sick critically ill patients.

Regional citrate anticoagulation for intermittent predilution online hemofiltration

There is no consensus on the optimal renal replacement treatment in intensive care units. Among intermittent dialysis methods, hemofiltration (HF) is preferred by some because of better hemodynamic stability and cytokine removal. We report our experience with regional citrate anticoagulation for intermittent predilution online HF. Forty-one patients (age 69 +/- 10 years, 73% male) with acute renal failure and an increased bleeding risk in intensive care units were included in this retrospective analysis. Citrate anticoagulation was performed with 4% citrate (starting at 400 mL/h) and 1 mol/L calcium chloride (starting at 7 mL/h). Calcium-containing (1.25 mmol/L) infusate, prepared online, was used. Anticoagulation was assessed visually after HF in a subgroup of 36 procedures using a score of 5 (no clotting) to 1 (total occlusion). The duration of the 94 HF sessions performed was 4 h 50 min +/- 47 min, and the infusate volume reached was 77 +/- 9 L. During HF, ionized calcium increased (1.01 +/- 0.14 to 1.13 +/- 0.09 mmol/L, P < 0.001), and the increases in sodium (141 +/- 5 to 143 +/- 3 mmol/L, P < 0.001) and bicarbonate (23 +/- 6 to 25 +/- 4 mmol/L, P < 0.01) were significant, but small. There were two cases of metabolic alkalosis (pH > 7.5) not requiring any intervention. None of the circuits clotted. The mean anticoagulation assessment scores were 4.6 +/- 0.6 at the arterial bubble trap, 4.2 +/- 1.0 at the dialyzer, and 4.2 +/- 0.9 at the venous bubble trap. To conclude, regional citrate anticoagulation for predilution online hemofiltration with calcium-containing infusate provides a good anti-thrombotic effect and has rare metabolic side effects.

Continuous renal replacement therapy in sepsis and multisystem organ failure

This study reviews the role of continuous renal replacement therapy (CRRT) in sepsis with acute kidney injury (AKI) and septic shock with multiple organ failure. In addition to the conventional aim of replacing renal function in AKI, CRRT is often used with the concept of modulating immune response in sepsis. With the intention of influencing circulating levels of inflammatory mediators like cytokines and chemokines, the complement system, as well as factors of the coagulation system, several modifications of CRRT have been developed over the last years. These include high volume hemofiltration, high adsorption hemofiltration, use of high cut-off membranes, and hybrid systems like coupled plasma filtration absorbance. One of the most promising concepts may be the development of renal assist devices using renal tubular cells for implementing renal tubular function into CRRT.

Impact of continuous venovenous hemofiltration on organ failure during the early phase of severe sepsis: a randomized controlled trial

OBJECTIVE

The impact of continuous venovenous hemofiltration on sepsis-induced multiple organ failure severity is controversial. We sought to assess the effect of early application of hemofiltration on the degree of organ dysfunction and plasma cytokine levels in patients with severe sepsis or septic shock.

DESIGN

Prospective, randomized, open, multicenter study setting, 12 French intensive care units.

PATIENTS

A total of 80 patients were enrolled within 24 hours of development of the first organ failure related to a new septic insult.

INTERVENTIONS

Patients were randomized to group 1 (HF), who received hemofiltration (25 mL/kg/hr) for a 96-hour period, or group 2 (C) who were managed conventionally.

MEASUREMENTS AND MAIN RESULTS

The primary end point was the number, severity, and duration of organ failures during 14 days, as evaluated by the Sepsis-Related Organ Failure Assessment score, on an intention-to-treat analysis. Strict guidelines were provided to perform continuous hemofiltration under the same conditions and bearing the same objectives in all centers. Because of inclusion stagnation, the trial was discontinued after an interim analysis by which time 76 patients had been randomized. The number and severity of organ failures were significantly higher in the HF group (p < 0.05). No modifications in plasma cytokine levels could be detected.

CONCLUSION

These data suggest that early application of standard continuous venovenous hemofiltration is deleterious in severe sepsis and septic shock. This study does not rule out an effect of high-volume hemofiltration (>35 mL/kg/hr) on the course of sepsis.

Circulating pro-apoptotic mediators in burn septic acute renal failure

The pathogenesis of septic acute kidney injury (AKI) is not well understood. In the present issue of Critical Care, the combined clinical and experimental study from Mariano's group provides new insight into the disease. The study shows that plasma from septic burn patients with acute renal failure initiated pro-apoptotic effects and functional alterations in renal tubular cells and podocytes in vitro that correlated with the degree of proteinuria and renal dysfunction. Pro-apoptotic effects were not attributable to antibiotic or uremic toxicity, but were partially attributable to endotoxin. Sepsis and burn had additive effects. Apart from increasing our understanding of the pathogenesis of septic AKI, the study justifies further research on therapeutic interventions in several directions. These include the binding and elimination of the source of endotoxin by selective decontamination of the digestive tract, the blocking of apoptotic pathways, or the extracorporeal removal of circulating toxic mediators using high permeability hemofiltration or coupled plasma filtration and absorption.

Renal replacement strategies in the ICU

Acute renal failure (ARF) with the concomitant need for renal replacement therapy (RRT) is a common complication of critical care medicine that is still associated with high mortality. Different RRT strategies, like intermittent hemodialysis, continuous venovenous hemofiltration, or hybrid forms that combine the advantages of both techniques, are available and will be discussed in this article. Since a general survival benefit has not been demonstrated for either method, it is the task of the nephrologist or intensivist to choose the RRT strategy that is most advantageous for each individual patient. The underlying disease, its severity and stage, the etiology of ARF, the clinical and hemodynamic status of the patient, the resources available, and the different costs of therapy may all influence the choice of the RRT strategy. ARF, with its risk of uremic complications, represents an independent risk factor for outcome in critically ill patients. In addition, the early initiation of RRT with adequate doses is associated with improved survival. Therefore, the "undertreatment" of ARF should be avoided, and higher RRT doses than those in patients with chronic renal insufficiency, independent of whether convective or diffusive methods are used, are indicated in critically ill patients. However, clear guidelines on the dose of RRT and the timing of initiation are still lacking. In particular, it remains unclear whether hemodynamically unstable patients with septic shock benefit from early RRT initiation and the use of increased RRT doses, and whether RRT can lead to a clinically relevant removal of inflammatory mediators.

Hemodialysis membrane with a high-molecular-weight cutoff and cytokine levels in sepsis complicated by acute renal failure: a phase 1 randomized trial

BACKGROUND

Sepsis is the leading cause of acute renal failure. Intermittent hemodialysis (IHD) is a common treatment for patients with acute renal failure. However, standard hemodialysis membranes achieve only little diffusive removal of circulating cytokines. Modified membranes may enable both successful IHD treatment and simultaneous diffusive cytokine removal.

STUDY DESIGN

Double-blind, crossover, randomized, controlled, phase 1 trial.

SETTING & PARTICIPANTS

Tertiary intensive care unit. 10 septic patients with acute renal failure according to RIFLE class F.

INTERVENTION

Each patient was treated with 4 hours of high-cutoff (HCO)-IHD and 4 hours of high-flux (HF)-IHD.

OUTCOMES & MEASUREMENTS

We chose relative change in plasma interleukin 6 (IL-6) concentrations from baseline to 4 hours as the primary outcome for effective cytokine removal. We measured plasma and effluent concentrations of cytokines (IL-6, IL-8, IL-10, and IL-18) and albumin.

RESULTS

Median age was 53 years (25(th) to 75(th) percentiles, 43 to 71 years). Both treatments achieved equal control of uremia. Four hours of HCO-IHD accomplished a greater decrease in plasma IL-6 levels (-30.3%) than 4 hours of HF-IHD (1.1%; P = 0.05). HCO-IHD, but not HF-IHD, achieved substantial diffusive clearance of several cytokines (IL-6, 14.1 mL/min; IL-8, 75.2 mL/min; and IL-10, 25.5 mL/min). Such clearance also was associated with greater relative decreases in plasma IL-8 and IL-10 levels in favor of HCO-IHD (P = 0.02, P = 0.04). We found significantly greater relative changes from prefilter to postfilter plasma IL-6, IL-8, and IL-10 values in favor of HCO-IHD (P = 0.02, P = 0.01, P < 0.01). During HCO-IHD, cumulative albumin loss into the effluent was 7.7 g (25(th) to 75(th) percentiles, 4.8 to 19.6) versus less than 1.0 g for HF-IHD (P < 0.01).

LIMITATIONS

Small phase 1 trial.

CONCLUSION

In septic patients with acute renal failure, HCO-IHD achieved simultaneous uremic control and diffusive cytokine clearances and a greater relative decrease in plasma cytokine concentrations than standard HF-IHD.

Renal replacement therapy in the treatment of acute renal failure-intermittent and continuous

Renal replacement therapy (RRT) is increasingly used in intensive care as acute renal failure (ARF) is a common and constantly increasing complication in this setting. Different forms of RRT such as intermittent hemodialysis, continuous hemofiltration, or hybrid forms, which combine advantages of both, are available and will be discussed in this article. As a general survival benefit for neither method has been demonstrated, it is the task of the nephrologist or intensivist to choose the RRT strategy that is most advantageous for each individual patient. The choice of RRT might depend not only on the underlying disease, the time course of the disease, the etiology of ARF, the actual clinical status of the patient but also on the resources available and the cost of therapy. An adequate dose of RRT seems to result in improved survival in patients with ARF. However, clear guidelines on the dose of RRT and the timing of initiation are still lacking. Moreover, it will be discussed whether patients with sepsis and septic shock benefit from early RRT initiation, the use of increased RRT doses, and increased removal of inflammatory mediators by RRT.

Hemofiltration in sepsis and systemic inflammatory response syndrome: the role of dosing and timing

INTRODUCTION

The benefit of hemofiltration (HF) as an adjunctive treatment of sepsis or the systemic inflammatory response syndrome (SIRS) in critically ill patients is a subject of severe debate. Firm conclusions on this subject are hampered by the heterogeneity in study populations and HF treatments, and the lack of adequately sized randomized controlled clinical trials. The aim of this review was to determine the importance of ultrafiltration dose and timing on the physiologic and clinical effects of HF in sepsis and SIRS. In addition, we discuss the issue of filter pore size.

METHODS

Literature search was done in Embase and PubMed database for animal and human studies.

RESULTS

Animal studies suggest beneficial effects of HF on hemodynamics; gas exchange; sepsis-induced immunoparalysis; histology of gut, lung, and kidney; and (short-term) survival. These effects were more prominent with "very high" ultrafiltrate rates (> or =100 mL/kg per hour) and early initiation of HF (ie, before or very early after the septic challenge). Three small randomized studies and 3 observational studies in patients with sepsis or SIRS show beneficial effects of short-term or pulse HF using very high ultrafiltrate rates and/or early initiation of HF on physiologic endpoints and survival. However, the studies were underpowered for survival. The first observations of high permeability HF (pore size, about 10 nm; in vitro cutoff, 100 kd) are promising, but so far, it has not been sufficiently examined to allow strong conclusions.

CONCLUSION

Human and animal studies suggest that early initiation and high ultrafiltrate volumes are determinants of the beneficial physiologic and clinical effect of HF in sepsis and SIRS. As yet, the evidence in humans is too low to recommend HF as an adjunctive therapy for critically ill patients with sepsis or SIRS. Regarding the many uncertainties about optimal volume (high or very high) and type of membrane, clinical studies should first focus on endpoints as recovery from organ failure and length of treatment before survival studies are started.

Pilot study on the effects of high cutoff hemofiltration on the need for norepinephrine in septic patients with acute renal failure

OBJECTIVE

High cutoff hemofilters are characterized by an increased effective pore size designed to facilitate the elimination of inflammatory mediators in sepsis. Clinical data on this new renal replacement modality are lacking.

DESIGN

Prospective, randomized clinical trial.

SETTING

University hospital, intensive care units.

PATIENTS

: Thirty patients with sepsis-induced acute renal failure.

INTERVENTION

Patients were allocated to high cutoff (n = 20) or conventional (n = 10) hemofiltration in a 2:1 ratio. Median renal replacement dose was 31 mL/kg/hr. For high cutoff hemofiltration, a high-flux hemofilter with an in vivo cutoff point of approximately 60 kilodaltons was used. Conventional hemofiltration was performed with a standard high-flux hemofilter (PF11S). The impacts of high cutoff hemofiltration on the need for norepinephrine and on plasma levels and clearance rates for interleukin (IL)-6 and IL-1 receptor antagonist (IL-1ra) were analyzed. Absolute values, but also adjusted values (expressed as proportion of baseline), were analyzed. The observation period was restricted to 48 hrs.

MAIN RESULTS

Apart from higher antithrombin III levels at entry into the study, main clinical and laboratory parameters were comparable between both groups. The median norepinephrine dose at entry into the study was 0.30 microg/kg/min in the high cutoff group and 0.21 microg/kg/min in the conventional hemofiltration group (p = .448). Only the high cutoff group showed a significant decline (p = .0002) in "adjusted" norepinephrine dose over time. Clearance rates for IL-6 and IL-1ra were significantly higher in the high cutoff hemofiltration group (p < .0001), which translated into a significant decline of the corresponding plasma levels (p = .0465 for IL-6; p = .0293 for IL-1ra).

CONCLUSION

In this pilot study, high cutoff hemofiltration has been shown to exert a beneficial effect on the need for norepinephrine in septic patients with acute renal failure. In addition, we demonstrate that high cutoff hemofiltration is superior to conventional hemofiltration in the elimination of IL-6 and IL-1ra from the circulating blood of septic patients.

Increased interleukin-6 after cardiac surgery predicts infection

Early diagnosis and treatment of infection after cardiac surgery with cardiopulmonary bypass (CPB) improves outcome. Conventional laboratory tests, such as C-reactive protein and white blood cell count can not distinguish patients with early infection from those with systemic inflammatory response syndrome but without infection. After CPB, there is a systemic release of proinflammatory and antiinflammatory cytokines, including tumor necrosis factor-alpha, interleukin (IL)-6, and IL-10. We investigated the predictive ability of these variables for infection after cardiac surgery. Forty-six patients with impaired left ventricular ejection fraction (<60%), scheduled for cardiac surgery, were included. Plasma samples were drawn 1 day before and immediately before surgery, on admission to the intensive care unit, and on days 1, 3, and 7 after surgery. Infection was identified according to the criteria of the Centers for Disease Control and Prevention. After surgery 13 patients developed an infection. In patients with infection, confirmed a median of 4 days after surgery, all measurements of IL-6, and IL-10 on postoperative day 3 were significantly increased. Tumor necrosis factor-alpha, leukocytes, and C-reactive protein were not increased in these patients. Immediately after surgery blood glucose was significantly increased in patients with infection. Increased IL-6 after CPB is predictive of infection after cardiac surgery in patients with impaired left ventricular function.