Effect of polymyxin B-immobilized fiber on bone resorption in patients with 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.

Up-to-date information on polymyxin B-immobilized fiber column direct hemoperfusion for septic shock

Endotoxin adsorption therapy by polymyxin B-immobilized fiber column direct hemoperfusion (PMX-DHP) has been used for the treatment of septic shock patients. Endotoxin, an outer membrane component of Gram-negative bacteria, plays an important role in the pathogenesis of septic shock. Endotoxin triggers a signaling cascade for leukocytes, macrophage, and endothelial cells to secrete various mediators including cytokines and nitric oxide, leading to septic shock and multiple organ dysfunction syndrome. PMX-DHP directly adsorbed not only endotoxin but also monocytes and anandamide. It reduced blood levels of inflammatory cytokines such as interleukin (IL)-1, IL-6, tumor necrosis factor-alpha and IL-17A, adhesion molecules, plasminogen activator inhibitor 1, and high mobility group box-1. As a result, PMX-DHP increased blood pressure and reduced the dose of vasoactive-inotropic agents. PMX-DHP improved monocyte human leukocyte antigen-DR expression in patients with severe sepsis and septic shock. A post hoc analysis of EUPHRATES (Evaluating the Use of Polymyxin B Hemoperfusion in Randomized Controlled Trial of Adults Treated for Endotoxemia and Septic Shock) trial has shown that PMX-DHP significantly reduced 28-day mortality compared with the control group in septic shock patients with endotoxin activity assay level between 0.60 and 0.89. Longer duration of PMX-DHP may be another strategy to bring out the beneficial effects of PMX-DHP. Further studies are needed to confirm the efficacy of PMX-DHP treatment for septic shock.

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.

Polymyxin B-immobilized hemoperfusion and mortality in critically ill adult patients with sepsis/septic shock: a systematic review with meta-analysis and trial sequential analysis

PURPOSE

Polymyxin B-immobilized hemoperfusion (PMX-HP) is an adjuvant therapy for sepsis or septic shock that clears circulating endotoxin. Prior trials have shown that PMX-HP improves surrogate endpoints. We aimed to conduct an evidence synthesis to evaluate the efficacy and safety of PMX-HP in critically ill adult patients with sepsis or septic shock.

METHODS

We searched for randomized controlled trials (RCTs) in MEDLINE, EMBASE, the Cochrane Library, the Health Technology Assessment Database, CINAHL, "Igaku Chuo Zasshi", the National Institute of Health Clinical Trials Register, the World Health Organization International Clinical Trials Registry Platform, the University Hospital Medical Information Network Clinical Trials Registry, the reference lists of retrieved articles, and publications by manufacturers of PMX-HP. The primary outcomes were 28-day all-cause mortality, the number of patients with at least one serious adverse event, and organ dysfunction scores. The GRADE methodology for the certainty of evidence was used.

RESULTS

Six trials (857 participants; weighted mean age 62.5 years) proved eligible. Patient-oriented primary outcomes were assessed. The pooled risk ratio (RR) for 28-day mortality associated with PMX-HP was 1.03 [95% confidence interval (CI) 0.78-1.36; I ² = 25%; n = 797]. The pooled RR for adverse events was 2.17 (95% CI 0.68-6.94; I ² = 0%; n = 717). Organ dysfunction scores over 24-72 h after PMX-HP treatment did not change significantly (standardized mean difference - 0.26; 95% CI - 0.64 to 0.12; I ² = 78%; n = 797). The certainty of the body of evidence was judged as low for both benefit and harm using the GRADE methodology.

CONCLUSIONS

There is currently insufficient evidence to support the routine use of PMX-HP to treat patients with sepsis or septic shock.

REGISTRATION

PROSPERO International Prospective Register of Systematic Reviews (CRD42016038356).

Polymyxin B-immobilized fiber column hemoperfusion mainly helps to constrict peripheral blood vessels in treatment for septic shock

BACKGROUND

Polymyxin B-immobilized fiber column hemoperfusion (PMX) has been reported to be effective for patients with septic shock. It remains unclear, however, how the efficacy of PMX varies according to the characteristics and underlying conditions of the patients treated. The objective of the present study was to clarify the factors that result in clinical efficacy of PMX treatment.

METHODS

We retrospectively investigated 78 consecutive patients with severe sepsis or septic shock who underwent PMX treatment. We reviewed the demographic data, routine biochemistry, microbiological data, infection focus, Acute Physiology and Chronic Health Evaluation (APACHE) II score, Sequential Organ Failure Assessment (SOFA) score, change in mean arterial pressure (MAP), inotropic score, vasopressor dependency index, plasma levels of endotoxin and lactate, PaO2/FIO2 ratio, and survival time. We also divided the patients into two groups for comparison, namely, those whose inotropic scores improved after PMX treatment (improvement group) and those whose inotropic scores did not improve (non-improvement group).

RESULTS

The inotropic score and the vasopressor dependency index significantly decreased from 18.1 to 9.9 (p < 0.05) and from 0.27 to 0.14 (p < 0.05), respectively, after PMX treatment in the overall study population, while no significant change in the PaO2/FIO2 ratio was observed (p = 0.96). The inotropic score at pre-PMX treatment was significantly higher in the improvement group than in the non-improvement group (p < 0.01). The improvement of the PaO2/FIO2 ratio after PMX treatment was significant in the improvement group (p < 0.05).

CONCLUSIONS

The improvement group's inotropic score was higher, because of peripheral blood vessels dilatation and requirement for more catecholamines. Therefore, our study suggests that PMX treatment is particularly useful for improving hemodynamics in septic shock patients with excessively dilated peripheral blood vessels.

Blood purification and mortality in sepsis: a meta-analysis of randomized trials

OBJECTIVES

Although blood purification improves outcomes in animal studies of sepsis, results of clinical trials have been mixed. We conducted a systematic review and meta-analysis of randomized trials to determine the association between various blood purification techniques and all-cause mortality in humans with sepsis.

DATA SOURCES

We searched for relevant studies in MEDLINE, EMBASE, and the Cochrane Library database from January 1966 to May 2012.

STUDY SELECTION

Inclusion required a diagnosis of sepsis and comparison of blood purification techniques including hemofiltration, hemoperfusion, plasma exchange, or hemodialysis with no blood purification (control group).

DATA EXTRACTION

Two authors independently selected studies and extracted data. Summary statistics, risk ratios, and CIs were calculated using random-effects modeling. Study quality was assessed using Jadad score, and publication bias was assessed using funnel plots and Egger's statistic.

DATA SYNTHESIS

Overall, blood purification decreased mortality compared with no blood purification (35.7% vs 50.1%; risk ratio, 0.69 [95% CI, 0.56-0.84]; p<0.001; 16 trials, n=827). However, these results were driven mainly by hemoperfusion (risk ratio, 0.63 [95% CI, 0.50-0.80]; p<0.001; 10 trials, n=557) and plasma exchange (risk ratio, 0.63 [95% CI, 0.42-0.96]; p=0.03; two trials, n=128). Pooling of all trials of blood purification for treatment of sepsis was no longer associated with lower mortality (risk ratio, 0.89 [95% CI, 0.71-1.13]; p=0.36; eight trials, n=457) after excluding trials using polymyxin B hemoperfusion.

CONCLUSIONS

Blood purification techniques including hemoperfusion, plasma exchange, and hemofiltration with hemoperfusion were associated with lower mortality in patients with sepsis. These results were mainly influenced by studies using polymyxin B hemoperfusion from Japan.

Immunomodulation in sepsis: the role of endotoxin removal by polymyxin B-immobilized cartridge

Severe sepsis results in high morbidity and mortality. Immunomodulation strategies could be an adjunctive therapy to treat sepsis. Endotoxin is a component of gram-negative bacteria and plays an important role in the pathogenesis of septic shock when it is recognized by immune cells. Removal of endotoxin could be an effective adjunctive approach to the management of sepsis. Devices to adsorb endotoxin or inflammatory cytokines have been designed as a strategy to treat severe sepsis, especially sepsis caused by gram-negative bacteria. Polymyxin B-immobilized cartridge has been successfully used to treat patients with sepsis of abdominal origin. Although this cartridge was conceived to adsorb endotoxin, several other immunological mechanisms have been elucidated, and this device has also yielded promising results in patients with nonseptic respiratory failure. In this paper, we summarize the immune modulation actions of Polymyxin B-immobilized cartridge to explore its potential usefulness beyond endotoxin elimination.

Polymyxin B-immobilized fiber column hemoperfusion therapy for septic shock

Endotoxin, an outer membrane component of gram-negative bacteria, plays an important role in the pathogenesis of septic shock. Endotoxin adsorption therapy by polymyxin B-immobilized fiber column hemoperfusion (PMX) has been used for the treatment of septic shock patients in Japan since 1994. The covalent binding of polymyxin B onto the surface of the polystyrene-based carrier fiber in PMX inactivates the endotoxin in the blood without exerting toxicity. This study was performed as a systematic review to evaluate the efficacy and mechanism of PMX treatment in patients with septic shock. The PubMed database and references from identified articles were used to search and review the literature relating to the efficacy and mechanism of PMX treatment in patients with septic shock. Polymyxin B-immobilized fiber column hemoperfusion adsorbed monocytes, activated neutrophils, and anandamide, as well as endotoxin through direct covalent bond, hydrophobic and ionic interactions, and hydrodynamics, and reduced the blood concentrations of inflammatory cytokines, plasminogen activator inhibitor 1 and adhesion molecules. Polymyxin B-immobilized fiber column hemoperfusion increased blood pressure and reduced the dosage requirements for vasopressive/inotropic agents. The meta-analysis showed that PMX treatment had beneficial effects on the hemodynamics, pulmonary oxygenation, and mortality. These beneficial effects may be attributable to the direct adsorption of endotoxin, monocytes, activated neutrophils, and anandamide, as well as indirect decrease in inflammatory cytokines and other mediators. Polymyxin B-immobilized fiber column hemoperfusion treatment has additional effects on reducing endothelial damage, proapoptotic activity, and immunosuppression. Further studies will be needed to confirm the efficacy and mechanism of PMX treatment in septic shock.

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.

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.

New concepts in the pathogenesis, diagnosis and treatment of bacteremia and sepsis

Bacteremia and sepsis are major health concerns. Despite intensive research, there are only a limited number of successful treatment options, and it is difficult to see the forest for the trees when considering the pathogenesis of this condition. Studies in the last decade have shown that a major pathophysiologic event in sepsis is the progression from proinflammation to an immunosuppressive state. However, recent genome-based data indicate that sepsis-related inflammatory responses are highly variable, which calls in question the classic two-phase model of sepsis. Adequate and timely antimicrobial treatment is a cornerstone for survival in patients with bacteremia and sepsis. However, microbial resistance has emerged as an increasing challenge for clinicians and with an increasing number of resistant pathogens causing infections, selection of empiric antimicrobial treatment has become difficult. Treatment options currently under way are targeted to enhance immune responses, rebalance the regulation of the dysregulated immune system, remove endotoxin and block/inhibit apoptosis.

Direct hemoperfusion with polymyxin-B-immobilized fiber columns improves septic hypotension and reduces inflammatory mediators in septic patients with colorectal perforation

PURPOSE

Although some studies have reported favorable effects of direct hemoperfusion with polymyxin-B-immobilized fiber columns (PMX) for the treatment of septic shock, few studies have demonstrated the efficacy of PMX in studies with a uniform case definition and without any other blood purification techniques.

MATERIALS AND METHODS

Fifty-two patients with severe sepsis or septic shock secondary to colorectal perforation were treated with PMX. Hemodynamic alterations and plasma concentrations of endotoxin, interleukin (IL)-1beta, IL-1 receptor antagonist (IL-1Ra), IL-6, IL-8, and IL-10 were evaluated following PMX treatment.

RESULTS

We observed a significant reduction in plasma endotoxin in the nonsurvivors immediately after PMX treatment compared to before treatment. Systolic blood pressure was markedly increased and circulating levels of IL-1beta, IL-1Ra, and IL-8 were significantly reduced during a 2-h interval of PMX.

CONCLUSIONS

Our findings suggested that PMX treatment appears to adsorb endotoxin and also modulates circulating cytokine during a 2-h interval of direct hemoperfusion in septic patients with such condition.

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.

Endotoxin apheresis for sepsis

The principle use of apheresis in the treatment of sepsis may be summarized as the removal of toxic substances and the restoration of normal organs function. It is ideal to control the early phases of inflammatory cascade when treating sepsis by removing microbial components, such as endotoxin or peptidoglycan. This review discusses endotoxin apheresis with particular emphasis on treatment using polymyxin B immobilized fiber columns (Toraymyxin) which are used widely in Japan for endotoxin removal therapy in patients with septic shock. Lixelle and CTR which have recently been shown to remove circulating bacterial components are also included in this review.