Caspase-3 and -8 activation and cytokine removal with a novel cellulose triacetate super-permeable membrane in an in vitro sepsis model

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

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

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.

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.

Polymyxin-B hemoperfusion inactivates circulating proapoptotic factors

Objective

To test the hypothesis that extracorporeal therapy with polymyxin B (PMX-B) may prevent Gram-negative sepsis-induced acute renal failure (ARF) by reducing the activity of proapoptotic circulating factors.

Setting

Medical-Surgical Intensive Care Units.

Patients and interventions

Sixteen patients with Gram-negative sepsis were randomized to receive standard care (Surviving Sepsis Campaign guidelines) or standard care plus extracorporeal therapy with PMX-B.

Measurements and results

Cell viability, apoptosis, polarity, morphogenesis, and epithelial integrity were evaluated in cultured tubular cells and glomerular podocytes incubated with plasma from patients of both groups. Renal function was evaluated as SOFA and RIFLE scores, proteinuria, and tubular enzymes. A significant decrease of plasma-induced proapoptotic activity was observed after PMX-B treatment on cultured renal cells. SOFA and RIFLE scores, proteinuria, and urine tubular enzymes were all significantly reduced after PMX-B treatment. Loss of plasma-induced polarity and permeability of cell cultures was abrogated with the plasma of patients treated with PMX-B. These results were associated to a preserved expression of molecules crucial for tubular and glomerular functional integrity.

Conclusions

Extracorporeal therapy with PMX-B reduces the proapoptotic activity of the plasma of septic patients on cultured renal cells. These data confirm the role of apoptosis in the development of sepsis-related ARF.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-008-1124-6) contains supplementary material, which is available to authorized users.

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.