Tailoring high-cut-off membranes and feasible application in sepsis-associated acute renal failure: in vitro studies

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.

Albumin Loss and Citrate Load in Pre-Dilution High Cut-Off-CVVHDF with Regional Citrate (18 mmol/L) and High Cut-Off CVVHD with Systemic Heparin: An in vitro Study

BACKGROUND

Convective therapies with high cut-off membranes (HCO) are usually not recommended because of theoretical excessive albumin loss. The aim of this in vitro study is to demonstrate the noninferior safety of pre-dilution hemodiafiltration with HCO (HCO-CVVHDF) with isotonic citrate anticoagulation (18 mmol/L) with respect to heparin anticoagulated hemodialysis with HCO (HCO-CVVHD) in terms of albumin removal and citrate load.

METHOD

-Albumin removal was compared in vitro between 3 pre--dilution-HCO-CVVHDF with citrate anticoagulation and 3 -HCO-CVVHD with heparin anticoagulation during 30-min single-pass and 180-min recirculation phases.

RESULTS

Considering concentrations and flows in the extracorporeal circuit, the transmembrane albumin removal was 2.06 (1.51; 2.09) g and 2.09 (1.9; 2.8) g respectively for HCO-CVVHDF and HCO-CVVHD, during the single-pass phase; 2.8 (2.67; 4.59) g and 2.54 (2.35; 4.67) g, respectively, for HCO-CVVHDF and HCO-CVVHD during the recirculation phase. Based on the citrate saturation coefficients, a citrate metabolic load of 8.86 mmol/h has been calculated for HCO-CVVHDF.

CONCLUSION

HCO-CVVHDF performed with regional anticoagulation with 18 mmol/L citrate solution does not induce higher -albumin transmembrane removal compared to HCO-CVVHD.

Super High-Flux Continuous Venovenous Hemodialysis Using Regional Citrate Anticoagulation: Long-Term Stability of Middle Molecule Clearance

Continuous renal replacement therapy is a standard treatment in critically ill patients with acute kidney injury. All CRRT techniques provide a high low-molecular weight clearance but even with hemofiltration, clearance of middle molecules is low. We investigated whether a new super high-flux hemofilter provides effective and sustained middle molecule clearance during citrate-anticoagulated continuous venovenous hemodialysis for up to 72 h. We included 14 critically ill patients with AKI-KDIGO-III in a prospective observational trial. We measured/calculated blood and urine concentrations, clearances and sieving coefficients of eight molecules with molecular weights from 60 to 66 kDa, hemodynamic parameters and SAPS-II scores. All filters were patent at 72 h. Clearance and sieving coefficients of small solutes were high and sustained over time, those for larger solutes decreased over 72 h but remained high enough to decrease blood concentrations of solutes up to 25 kDa. Albumin serum levels remained unaffected. Catecholamine doses and SAPS-II scores decreased significantly. This new hemofilter may improve blood purification in critically ill patients with AKI.

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.

Clinical Benefits of High-Volume Hemofiltration in Critically Ill Pediatric Patients with Severe Sepsis: A Retrospective Cohort Study

AIMS

The study aimed to assess the clinical benefits of high-volume hemofiltration (HVHF) in pediatric patients with severe sepsis compared with standard-volume continuous veno-venous hemofiltration (CVVH).

METHODS

We retrospectively analyzed the medical records of 155 pediatric patients with severe sepsis admitted to the pediatric intensive care unit of Shanghai Children's Hospital from January 2010 to June 2016. A total of 93 patients were treated with HVHF and 62 patients were treated with CVVH.

RESULTS

HVHF treatment did not significantly reduce 28-day mortality. Moreover, there was no significant difference in reducing the plasma level of inflammatory mediators and improving hemodynamic variables between HVHF and CVVH group. However, the incidence of hyperglycemia was significantly higher in HVHF group than in CVVH group.

CONCLUSIONS

There is no evidence to indicate that HVHF is superior to CVVH in reducing 28-day mortality as an adjunct to the treatment of severe sepsis in pediatric patients.

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.

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.

Acute kidney injury in the ICU: from injury to recovery: reports from the 5th Paris International Conference

The French Intensive Care Society organized its yearly Paris International Conference in intensive care on June 18-19, 2015. The main purpose of this meeting is to gather the best experts in the field in order to provide the highest quality update on a chosen topic. In 2015, the selected theme was: "Acute Renal Failure in the ICU: from injury to recovery." The conference program covered multiple aspects of renal failure, including epidemiology, diagnosis, treatment and kidney support system, prognosis and recovery together with acute renal failure in specific settings. The present report provides a summary of every presentation including the key message and references and is structured in eight sections: (a) diagnosis and evaluation, (b) old and new diagnosis tools,

Acute kidney injury in the ICU: from injury to recovery: reports from the 5th Paris International Conference

The French Intensive Care Society organized its yearly Paris International Conference in intensive care on June 18-19, 2015. The main purpose of this meeting is to gather the best experts in the field in order to provide the highest quality update on a chosen topic. In 2015, the selected theme was: "Acute Renal Failure in the ICU: from injury to recovery." The conference program covered multiple aspects of renal failure, including epidemiology, diagnosis, treatment and kidney support system, prognosis and recovery together with acute renal failure in specific settings. The present report provides a summary of every presentation including the key message and references and is structured in eight sections: (a) diagnosis and evaluation, (b) old and new diagnosis tools,

Effectiveness of High Cut-Off Hemofilters in the Removal of Selected Cytokines in Patients During Septic Shock Accompanied by Acute Kidney Injury-Preliminary Study

Background

In recent years there have been attempts to treat sepsis using various methods of extracorporeal blood purification in order to eliminate selected mediators of inflammation.

Material/Methods

This retrospective study assessed 28 patients (17 males, 11 females, age 60.3 ± 14.5 years) in septic shock, treated with continuous venovenous hemodialysis (CVVHD). Oligoanuric patients with acute kidney injury were qualified for 24-hour CVVHD using high cut-off (HCO) hemofilter. Before the start of dialysis and after 24 hours of treatment, the concentration levels of selected cytokines (IFN-α, IFN-γ, TNF-α, IL-1β, IL-2, IL-6, IL-10, IL-12) in serum were assessed. After 12 hours and 24 hours of treatment, the concentration of the same cytokines in the dialysis fluid was assessed. The aim of our study was to evaluate the effectiveness of HCO-CVVHD in the removal of selected cytokines.

Results

After 24-hour HCO-CVVHD treatment, IL-10 and IL-12 levels in serum were significantly lower. Concentrations of INF-α, IL-1β and IL-2 in dialysis fluid significantly increased during HCO-CVVHD, which corresponded with the parallel rise of related clearances. Clearance of IL-6 was approximately four times higher than IL-10. The rise of IL-6 during HCO-CVVHD significantly correlated with mortality due to sepsis.

Conclusions

Continuous venovenous hemodialysis using high cut-off hemofilter proved to be effective in the removal of IFN-α, IL-1β, IL-2 and IL-6, IL-10 and IL-12 from serum in patients during septic shock. The rise of IL-6 during HCO-CVVHD seems to be a marker of bad prognosis in septic shock patients.

High-Dose Versus Conventional-Dose Continuous Venovenous Hemodiafiltration and Patient and Kidney Survival and Cytokine Removal in Sepsis-Associated Acute Kidney Injury: A Randomized Controlled Trial

BACKGROUND

Soluble inflammatory mediators are known to exacerbate sepsis-induced acute kidney injury (AKI). Continuous renal replacement therapy (CRRT) has been suggested to play a part in immunomodulation by cytokine removal. However, the effect of continuous venovenous hemodiafiltration (CVVHDF) dose on inflammatory cytokine removal and its influence on patient outcomes are not yet clear.

STUDY DESIGN

Prospective, randomized, controlled, open-label trial.

SETTING & PARTICIPANTS

Septic patients with AKI receiving CVVHDF for AKI.

INTERVENTION

Conventional (40mL/kg/h) and high (80mL/kg/h) doses of CVVHDF for the duration of CRRT.

OUTCOMES

Patient and kidney survival at 28 and 90 days, circulating cytokine levels.

RESULTS

212 patients were randomly assigned into 2 groups. Mean age was 62.1 years, and 138 (65.1%) were men. Mean intervention durations were 5.4 and 6.2 days for the conventional- and high-dose groups, respectively. There were no differences in 28-day mortality (HR, 1.02; 95% CI, 0.73-1.43; P=0.9) or 28-day kidney survival (HR, 0.96; 95% CI, 0.48-1.93; P=0.9) between groups. High-dose CVVHDF, but not the conventional dose, significantly reduced interleukin 6 (IL-6), IL-8, IL-1b, and IL-10 levels. There were no differences in the development of electrolyte disturbances between the conventional- and high-dose groups.

LIMITATIONS

Small sample size. Only the predilution CVVHDF method was used and initiation criteria were not controlled.

CONCLUSIONS

High CVVHDF dose did not improve patient outcomes despite its significant influence on inflammatory cytokine removal. CRRT-induced immunomodulation may not be sufficient to influence clinical end points.

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.

Techniques of extracorporeal cytokine removal: a systematic review of the literature

BACKGROUND AND AIMS

Attempts at achieving cytokine homeostasis include blood purification to deliver cytokine removal. Assessment of ex vivo studies for optimal operating conditions is a vital step.

METHODS

We conducted a systematic search for ex vivo studies on cytokine removal using known modalities of extracorporeal circulation. We selected 29 articles and analyzed data according to clearance, sieving coefficient, ultrafiltrate concentration and percentage removal.

RESULTS

We identified four main techniques for cytokine removal: standard techniques, high cut-off (HCO) techniques, adsorption techniques and combined plasma filtration adsorption. HCO hemofiltration (HCO/HF) showed greatest consistency in cytokine removal among all approaches. Mean albumin clearance with HCO filters was 3.74 ml/min.

CONCLUSION

Ex vivo data support the view that HCO/HF is the most consistently effective approach in terms of sieving and clearance. Further investigation of HCO/HF in randomized controlled trials in animal models and humans seems desirable.

Extracorporeal therapies in sepsis

The treatment of sepsis is an ongoing challenge for clinicians; despite the wide choice of effective antibiotics to treat infection, sepsis remains the leading cause of morbidity and mortality for patients admitted to an intensive care unit. Dysregulation of the immune response is now recognized to be a key factor in multiple organ dysfunction, yet our therapy for inflammation remains ineffective. It has been advocated for more than a decade that cytokine reduction in blood compartment could lead to a reduction in mortality in sepsis. Over the years, multiple extracorporeal techniques have evolved, with the intent of influencing the circulating levels of inflammatory mediators like cytokines and chemokines, the complement system, as well as factors of the coagulation system. These include high-volume hemofiltration, use of high cutoff membranes, and systems based on adsorption, such as coupled plasma filtration adsorption and the polymyxin-B column. In addition, new experimental systems that utilize human phagocytic cells and immobilized antibodies for targeted immunomodulation have emerged. In the context of limited resources and growing expansion in the availability of technologies, a better understanding of these therapies is required before they can be properly integrated into standard clinical practice in the hope of influencing major clinical outcomes. In this article, we will provide a concise overview of selected extracorporeal modalities currently in clinical use and briefly introduce some new promising techniques for sepsis.

Cytokines in blood from septic patients interact with surface-immobilized heparin

When passing blood from septic patients through a column packed with surface heparinized beads, we were able to significantly reduce concentrations of the proinflammatory cytokine tumor necrosis factor (TNF)-alpha from initially very high levels. Passage of blood over nonheparinized beads did not affect the TNF levels. Meanwhile, concentrations of the regulated on activation, normal T-cells expressed, and secreted leukocyte activating cytokine (RANTES) remained unchanged following passage through the heparinized column, but rose significantly after passage through a column packed with the nonheparinized control beads. We conclude that surface heparinization may be a useful technique for selectively regulating the levels of heparin-binding cytokines from whole blood. This may have potential implications for the treatment of hyper-inflammatory conditions such as severe sepsis. Our data also suggests that surface activation and its associated inflammatory response may be avoided by using heparinization of the extracorporeal circuit.

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.

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.

Cystatin C in critically ill patients treated with continuous venovenous hemofiltration

Assessment of residual renal function in critically ill patients with acute renal failure (ARF) treated with continuous venovenous hemofiltration (CVVH) is difficult. Cystatin C (CysC) is a low-molecular-weight protein (13.3 kDa) removed from the body by glomerular filtration. Its serum concentration has been advocated for assessment of renal function in patients with kidney disease. To investigate whether the removal of CysC by CVVH is likely to influence its serum concentration, concentrations of CysC were measured in 3 consecutive samples in 18 patients with oliguric ARF treated with CVVH (2 L/hr). Samples were taken from the afferent and efferent blood lines and from the ultrafiltrate line. Concentrations of CysC did not change during the time interval studied. The mean serum concentrations of CysC were 2.25+/-0.45 mg/L in the afferent and 2.19+/-0.56 mg/L in the efferent samples (NS); ultrafiltrate concentrations of CysC were 1.01+/-0.45 mg/L. The sieving coefficient of CysC was 0.52+/-0.20; the clearance of CysC was 17.3+/-6.6 mL/min; and the quantity of CysC removed averaged 2.13 mg/hr. During CVVH (2 L/hr), the quantity of CysC removed is less than 30% of its production and no rapid changes in its serum concentration are observed. Therefore, CVVH (2 L/hr) is unlikely to influence serum concentrations of CysC significantly, which suggests that it can be used to monitor residual renal function during CVVH.

Oxidatively-modified and glycated proteins as candidate pro-inflammatory toxins in uremia and dialysis patients

End stage renal disease (ESRD) patients accumulate blood hallmarks of protein glycation and oxidation. It is now well established that these protein damage products may represent a heterogeneous class of uremic toxins with pro-inflammatory and pro-oxidant properties. These toxins could be directly involved in the pathogenesis of the inflammatory syndrome and vascular complications, which are mainly sustained by the uremic state and bioincompatibility of dialysis therapy. A key underlying event in the toxicity of these proteinaceous solutes has been identified in scavenger receptor-dependent recognition and elimination by inflammatory and endothelial cells, which once activated generate further and even more pronounced protein injuries by a self-feeding mechanism based on inflammation and oxidative stress-derived events. This review examines the literature and provides original information on the techniques for investigating proteinaceous pro-inflammatory toxins. We have also evaluated therapeutic - either pharmacological or dialytic - strategies proposed to alleviate the accumulation of these toxins and to constrain the inflammatory and oxidative burden of ESRD.

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.

Extracorporeal Therapies in the Treatment of Sepsis: Experience and Promise

Desire to restore the balance of body elements has enamored physicians since the ancient practice of bloodletting. More recently, extracorporeal techniques have been employed in both adults and children in treating sepsis. Extracorporeal therapies include continuous renal replacement (CRRT), plasma-based removal techniques, and extracorporeal membrane oxygenation (ECMO). These treatments could theoretically 1) provide immunohomeostasis of pro- and anti-inflammatory cytokines and other sepsis mediators, 2) decrease organ microthrombosis through removal of pro-coagulant factors and modulating the impaired septic coagulation response in sepsis, and 3) provide mechanical support of organ perfusion during the acute septic episode to allow time for response to traditional sepsis therapies and antimicrobials. CRRT is beneficial in managing fluid overload and acute renal failure in sepsis. Removal of sepsis mediators through the technique is variable, and the outcome impact of CRRT on sepsis has not been definitively determined. High-flow CRRT has demonstrated benefit in septic adults. Intriguing early results suggest that plasma exchange could improve outcomes in both adults and children. Based on experience, ECMO is recommended for refractory septic shock in neonates and should be considered for use in children. Ongoing trials may help determine whether the promise of extracorporeal therapies translates into outcome improvement in septic children.