Effects of polymyxin B immobilized fiber on urinary N-acetyl-beta-glucosaminidase in patients with severe sepsis

Blood Purification for Adult Patients With Severe Infection or Sepsis/Septic Shock: A Network Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

This study aimed to conduct a comprehensive and updated systematic review with network meta-analysis (NMA) to assess the outcome benefits of various blood purification modalities for adult patients with severe infection or sepsis.

DATA SOURCES

We conducted a search of PubMed, MEDLINE, clinical trial registries, Cochrane Library, and Embase databases with no language restrictions.

STUDY SELECTION

Only randomized controlled trials (RCTs) were selected.

DATA EXTRACTION

The primary outcome was overall mortality. The secondary outcomes were the length of mechanical ventilation (MV) days and ICU stay, incidence of acute kidney injury (AKI), and kidney replacement therapy requirement.

DATA SYNTHESIS

We included a total of 60 RCTs with 4,595 participants, comparing 16 blood purification modalities with 17 interventions. Polymyxin-B hemoperfusion (relative risk [RR]: 0.70; 95% CI, 0.57-0.86) and plasma exchange (RR: 0.61; 95% CI, 0.42-0.91) were associated with low mortality (very low and low certainty of evidence, respectively). Because of the presence of high clinical heterogeneity and intransitivity, the potential benefit of polymyxin-B hemoperfusion remained inconclusive. The analysis of secondary outcomes was limited by the scarcity of available studies. HA330 with high-volume continuous venovenous hemofiltration (CVVH), HA330, and standard-volume CVVH were associated with shorter ICU stay. HA330 with high-volume CVVH, HA330, and standard-volume CVVH were beneficial in reducing MV days. None of the interventions showed a significant reduction in the incidence of AKI or the need for kidney replacement therapy.

CONCLUSIONS

Our NMA suggests that plasma exchange and polymyxin-B hemoperfusion may provide potential benefits for adult patients with severe infection or sepsis/septic shock when compared with standard care alone, but most comparisons were based on low or very low certainty evidence. The therapeutic effect of polymyxin-B hemoperfusion remains uncertain. Further RCTs are required to identify the specific patient population that may benefit from extracorporeal blood purification.

Effect of Extracorporeal Blood Purification on Mortality in Sepsis: A Meta-Analysis and Trial Sequential Analysis

OBJECTIVE

The objective of this study was to conduct a meta-analysis and trial sequential analysis (TSA) of published randomized controlled trials (RCTs) to determine whether mortality benefit exists for extracorporeal blood purification techniques in sepsis.

DATA SOURCES

A systematic search on MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials for RCTs was performed.

STUDY SELECTION

RCTs investigating the effect of extracorporeal blood purification device use on mortality among critically ill septic patients were selected.

DATA EXTRACTION

Mortality was assessed using Mantel-Haenszel models, and I2 was used for heterogeneity. Data are presented as odds ratios (OR); 95% confidence intervals (CIs); p values; I2. Using the control event mortality proportion, we performed a TSA and calculated the required information size using an anticipated intervention effect of a 14% relative reduction in mortality.

DATA SYNTHESIS

Thirty-nine RCTs were identified, with 2,729 patients. Fourteen studies used hemofiltration (n = 789), 17 used endotoxin adsorption devices (n = 1,363), 3 used nonspecific adsorption (n = 110), 2 were cytokine removal devices (n = 117), 2 used coupled plasma filtration adsorption (CPFA) (n = 207), 2 combined hemofiltration and perfusion (n = 40), and 1 used plasma exchange (n = 106). On conventional meta-analysis, hemofiltration (OR 0.56 [0.40-0.79]; p < 0.001; I2 = 0%), endotoxin removal devices (OR 0.40 [0.23-0.67], p < 0.001; I2 = 71%), and nonspecific adsorption devices (OR 0.32 [0.13-0.82]; p = 0.02; I2 = 23%) were associated with mortality benefit, but not cytokine removal (OR 0.99 [0.07-13.42], p = 0.99; I2 = 64%), CPFA (OR 0.50 [0.10-2.47]; p = 0.40; I2 = 64%), or combined hemofiltration and adsorption (OR 0.71 [0.13-3.79]; p = 0.69; I2 = 0%). TSA however revealed that based on the number of existing patients recruited for RCTs, neither hemofiltration (TSA-adjusted CI 0.29-1.10), endotoxin removal devices (CI 0.05-3.40), nor nonspecific adsorption devices (CI 0.01-14.31) were associated with mortality benefit.

CONCLUSION

There are inadequate data at present to conclude that the use of extracorporeal blood purification techniques in sepsis is beneficial. Further adequately powered RCTs are required to confirm any potential mortality benefit, which may be most evident in patients at greatest risk of death.

The Effect of Three Different Miniaturized Blood Purification Devices on Plasma Cytokine Concentration in an Ex Vivo Model of Endotoxinemia

Purpose

A novel type of adsorptive plasma filtering device (ETX-A) capable of removing endotoxin from blood in a single step has recently been developed using nanotechnology.

Methods

In a miniaturized, ex vivo model of extracorporeal circuits, we tested the capacity to reduce plasma cytokine concentration of ETX-A filters in comparison to standard high-flux (HF) filters, high cut-off (HCO) filters and a control. Blood from six healthy volunteers was spiked with endotoxin and then circulated through closed (ETX-A, control) or open (HF, HCO) circuits. Blood flow was set at 16 ml/min and filtration flow at 1 ml/min. Samples for measurement of IL-1ra and IL-6 were taken at baseline and at 4 hours.

Results

Compared to control (703.3 [850.6] pg/mL), in HCO (383.5 [1144.1] pg/mL) and ETX-A (490.1 [683.2] pg/mL) filters, plasma IL-1ra pooled pre- and postfilter concentrations were lower at the end of the experiment (P=0.002; P=0.050, respectively) whereas, in standard HF filters, IL-1ra concentration was higher than control. HCO showed a trend toward a reduced relative increase in IL-6 concentration from commencement to end of experiment compared to control (P=0.07). After pooling end-of-experiment plasma cytokine values of novel blood purification devices, we found HCO + ETX-A superior to H with regard to reduction of IL-1ra (-27.0 [−20.5]% vs. 8.1 [18.9]%; P<01) and IL-6 (-18.0 [38.3]% vs. −1.1 [24.3]%; P=0.050) compared to control.

Conclusions

HCO and ETX-A appeared to significantly reduce plasma IL-1ra and, when combined, plasma IL-6 concentration as well. It appears desirable to manufacture full-size blood purification devices using this technology and to explore their effect on cytokine removal.

Coupled plasma haemofiltration filtration in severe sepsis: systematic review and meta-analysis

INTRODUCTION

Coupled plasma filtration and adsorption (CPFA) has been used in the treatment of severe sepsis with the intention of removing the proinflammatory and anti-inflammatory mediators from the systemic circulation. It is believed that this interrupts and moderates the septic cascade, but there is uncertainty about the benefits of this therapy.

METHODS

A systematic review and meta-analysis were performed to estimate the effects of CPFA on mortality in severe sepsis. The Cochrane CENTRAL Register of Controlled Trials, CINAHL, EMBASE, MEDLINE-EBSCO-Host, MEDLINE and ProQuest, were searched from 1997 to 2013. Randomised controlled trials, prospective cohort studies and retrospective cohort studies were included using the Centre for Reviews and Dissemination (CRD) framework. Data were abstracted using standard pro forma, and studies independently reviewed by two authors to confirm inclusion criteria. Quality of studies and risk of bias were assessed using the Grading of Recommendations, Assessment, Development and Evaluation Working Group (GRADE) and Critical Appraisal Skills (CASP) criteria, respectively. Meta-analysis was performed using Review Manager (RevMan V.5.1) software. The primary outcome was 28-day mortality. Secondary outcomes were mediator adsorption (picograms/mL), mean arterial BP (mm Hg) and oxygenation ratio.

RESULTS

17 studies met the inclusion criteria (n=441 patients, 242 CPFA). 14 studies reported the primary outcome of 28-day mortality. There were 88 deaths in CPFA patients versus 118 in those receiving haemofiltration: OR 0.34 (95% CI 0.24 to 0.13). Point estimates of effect on the secondary outcomes of mean arterial pressure and oxygen ratio favoured CPFA. Studies were small and heterogenous.

CONCLUSIONS

Evidence for CPFA in severe sepsis is sparse, of poor quality and further research is required, however, this meta-analysis noted improvements in survival rates of those patients treated with CPFA.

Direct hemoperfusion with polymyxin B immobilized fiber for abdominal sepsis in Europe

Since direct hemoperfusion with polymyxin B immobilized fiber (PMX-DHP) received its product certification for use in Europe in 1998, several prospective randomized controlled trials (RCTs) have been conducted in European countries. The first RCT, performed in six European academic medical centers in 2005, concluded that PMX-DHP is associated with improved hemodynamic status and cardiac function. Subsequently, a meta-analysis of PMX-DHP was presented in Italy in 2007. This systematic review found positive effects of PMX-DHP on mean arterial pressure and dopamine/ dobutamine use, PaO2/FiO2 ratio, endotoxin removal, and mortality. However, like most trials on extracorporeal therapies, none of the studies was double-blinded. The EUPHAS study, a multicenter RCT performed in ten Italian intensive care units in 2009, found that PMX-DHP improved 28-day survival, blood pressure, vasopressor requirement, and degree of organ failure. However, investigators in Belgium and Canada pointed out that there was no statistical difference in 28-day survival. Two more RCTs, the ABDO-MIX and EUPHRATES studies, the primary end points of which are 28-day mortality, were started in Europe and the United States at the end of 2010. We are hoping that these RCTs will resolve this issue.

Preventing acute kidney injury after noncardiac surgery

PURPOSE OF REVIEW

In surgical patients, outcome is strictly dependent on the occurrence of postoperative complications, and a postoperative failing kidney has a significant independent effect on outcome. Acute kidney injury (AKI) occurs in 1% of noncardiac surgical patients and is commonly associated with more serious complications. It is important to prevent AKI wherever possible.

RECENT FINDINGS

The mainstay of postoperative AKI prevention is perioperative maintenance of blood volume with adequate cardiac output by hemodynamic monitoring and fluids/inotropes infusion. There is a growing interest for pharmacological and metabolic interventions. Most interventions, however, have been predominantly evaluated in cardiac surgery and no definite conclusion can be translated in other settings. Tight control of glycemia is still matter of debate and a role, if any, may be limited to cardiac surgical patients.

SUMMARY

Adopting adequate nephroprotective strategies is favored by knowing the moment of the actual insult to the kidney. Nevertheless, in the literature too many areas of uncertainty still exist due to the lack of renal risk stratification, of adequately powered studies, of uniform AKI definition, and of appropriate sample composition. The only recommendation for renal protection still consists in maintaining an optimal blood volume and an adequate cardiac output.

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.

Effectiveness of polymyxin B-immobilized fiber column in sepsis: a systematic review

INTRODUCTION

Severe sepsis and septic shock are common problems in the intensive care unit and carry a high mortality. Endotoxin, one of the principal components on the outer membrane of gram-negative bacteria, is considered important to their pathogenesis. Polymyxin B bound and immobilized to polystyrene fibers (PMX-F) is a medical device that aims to remove circulating endotoxin by adsorption, theoretically preventing the progression of the biological cascade of sepsis. We performed a systematic review to describe the effect in septic patients of direct hemoperfusion with PMX-F on outcomes of blood pressure, use of vasoactive drugs, oxygenation, and mortality reported in published studies.

METHODS

We searched PubMed, the Cochrane Collaboration Database, and bibliographies of retrieved articles and consulted with experts to identify relevant studies. Prospective and retrospective observational studies, pre- and post-intervention design, and randomized controlled trials were included. Three authors reviewed all citations. We identified a total of 28 publications - 9 randomized controlled trials, 7 non-randomized parallel studies, and 12 pre-post design studies - that reported at least one of the specified outcome measures (pooled sample size, 1,425 patients: 978 PMX-F and 447 conventional medical therapy).

RESULTS

Overall, mean arterial pressure (MAP) increased by 19 mm Hg (95% confidence interval [CI], 15 to 22 mm Hg; p < 0.001), representing a 26% mean increase in MAP (range, 14% to 42%), whereas dopamine/dobutamine dose decreased by 1.8 microg/kg per minute (95% CI, 0.4 to 3.3 microg/kg per minute; p = 0.01) after PMX-F. There was significant intertrial heterogeneity for these outcomes (p < 0.001), which became non-significant when analysis was stratified for baseline MAP. The mean arterial partial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio increased by 32 units (95% CI, 23 to 41 units; p < 0.001). PMX-F therapy was associated with significantly lower mortality risk (risk ratio, 0.53; 95% CI, 0.43 to 0.65). The trials assessed had suboptimal method quality.

CONCLUSION

Based on this critical review of the published literature, direct hemoperfusion with PMX-F appears to have favorable effects on MAP, dopamine use, PaO2/FiO2 ratio, and mortality. However, publication bias and lack of blinding need to be considered. These findings support the need for further rigorous study of this therapy.