Use of Cytokine Filters During Cardiopulmonary Bypass: Systematic Review and Meta-Analysis

INTRODUCTION

Cardiac surgery involving cardiopulmonary bypass (CPB) activates an inflammatory response releasing cytokines that are associated with less favourable outcomes. This study aims to compare i) CPB during cardiac surgery (control) versus ii) CPB with haemoadsorption therapy; and assess the effect of adding this therapy in reducing the inflammatory cytokines burden.

METHODS

A systematic literature review with metanalysis was conducted regarding the main outcomes (operative mortality, ventilation duration, intensive care unit [ICU] and hospital stays) and day-1 inflammatory markers levels post-surgery. Fifteen (15) studies were included for final analysis (eight randomised controlled trials, seven observational studies) with no evidence of publication bias.

RESULTS

Subgroup analysis of non-elective surgeries across observational studies (emergency and infective endocarditis) significantly favoured cytokine filters in terms of 30-day mortality (OR 0.40, 95% CI 0.20, 0.83; p=0.01) and shorter ICU stay (MD -42.36, 95% CI -68.07, -16.65; p=0.001). At day-1 post-surgery, there was a significant difference favouring the cytokine filter group in c-reactive protein (CRP) (MD -0.71, 95% CI -0.84, -0.59; p<0.001) with no differences in white blood count (WBC), procalcitonin (PCT), tumour necrosis factor-alpha (TNF-α), IL-6, IL-8 and lactate. When comparing cytokine filters and control across all studies there was no significant difference in operative mortality, ventilation duration, hospital stay and ICU length of stay. Also, there were no statistical differences in randomised controlled trials (RCTs) using haemadsorption filters.

CONCLUSIONS

A significant reduction in 30-day mortality and ICU stay could be obtained by using haemadsorption therapy during non-elective cardiac surgery, especially emergency surgery and in patients with higher inflammatory burden such as infective endocarditis.

Advances in the Development of Biomaterials for Endotoxin Adsorption in Sepsis

Sepsis, a life-threatening and intractable disease without any specific treatment, is activated by endotoxin. Some attempts at removing endotoxin to treat sepsis from the blood circulation using different hemoperfusion cartridges have been proposed recently, but they have failed to reduce the mortality of severe septic patients. This review summarizes the latest advances in the development of endotoxin adsorbents. In particular, we highlight two critical parameters for endotoxin adsorbents when they are applied in blood purification: the dissociation constant and the maximum adsorption capacity. We also discuss potential challenges and research directions for the future development of endotoxin adsorbents.

RECCAS - REmoval of Cytokines during CArdiac Surgery: study protocol for a randomised controlled trial

Background

On-pump cardiac surgery triggers a significant postoperative systemic inflammatory response, sometimes resulting in multiple-organ dysfunction associated with poor clinical outcome. Extracorporeal cytokine elimination with a novel haemoadsorption (HA) device (CytoSorb®) promises to attenuate inflammatory response. This study primarily assesses the efficacy of intraoperative HA during cardiopulmonary bypass (CPB) to reduce the proinflammatory cytokine burden during and after on-pump cardiac surgery, and secondarily, we aim to evaluate effects on postoperative organ dysfunction and outcomes in patients at high risk.

Methods/design

This will be a single-centre randomised, two-arm, patient-blinded trial of intraoperative HA in patients undergoing on-pump cardiac surgery. Subjects will be allocated to receive either CPB with intraoperative HA or standard CPB without HA. The primary outcome is the difference in mean interleukin 6 (IL-6) serum levels between the two study groups on admission to the intensive care unit. A total number of 40 subjects was calculated as necessary to detect a clinically relevant 30 % reduction in postoperative IL-6 levels. Secondary objectives evaluate effects of HA on markers of inflammation up to 48 hours postoperatively, damage to the endothelial glycocalyx and effects on clinical scores and parameters of postoperative organ dysfunction and outcomes.

Discussion

In this pilot trial we try to assess whether intraoperative HA with CytoSorb® can relevantly reduce postoperative IL-6 levels in patients undergoing on-pump cardiac surgery. Differences in secondary outcome variables between the study groups may give rise to further studies and may lead to a better understanding of the mechanisms of haemoadsorption.

Trial registration

German Clinical Trials Register number DRKS00007928 (Date of registration 3 Aug 2015)

Endotoxin Elimination in Patients with Septic Shock: An Observation Study

To evaluate the effectiveness of endotoxin elimination with an adsorption column in patients with septic shock and endotoxemia. The elimination therapy was guided by a new bedside method of measuring endotoxin activity (EA). Intensive care unit (ICU) patients with septic shock and suspected Gram-negative infection were consecutively added to the study group within the first 24 h. Endotoxin elimination was performed using hemoperfusion with the Alteco LPS Adsorber. The primary endpoint was improvement in organ function within the first 24 h of treatment. A secondary objective was to assess the usefulness of a new method of measuring EA to help guide endotoxin elimination therapy. Out of 64 patients 18 had a high baseline EA [0.70 EA units (0.66–0.77)]. Those patients had endotoxin elimination treatment in addition to conventional medical therapy. At 24 h after endotoxin elimination, the EA had decreased to 0.56 EA units (0.43–0.77), (p = 0.005); MAP increased from 69 (62–80) to 80 mm Hg (68–88), (p = 0.002), and noradrenaline use decreased from 0.28 (0.15–0.80) to 0.1 μg/kg/min (0.00–0.70) at the same time (p = 0.04). The SOFA score had decreased from 11 (9–15) to 9 (7–14) points 24 h after endotoxin elimination (p = 0.01) with a median delta SOFA –2 points. Endotoxin elimination did not have a significant effect on the ICU length of stay or ICU mortality. Effective endotoxin elimination resulted in a significant improvement in hemodynamic parameters and of organ function. The application of the EA assay was useful for the bedside monitoring of endotoxemia in critically ill ICU patients.

Endotoxin adsorbents in extracorporeal blood purification: do they fulfill expectations?

INTRODUCTION

Lipopolysaccharides (LPS) are extremely strong stimulators of inflammatory reactions, act at very low concentrations, and are involved in the pathogenesis of sepsis and septic shock. Because of its toxicity, the efficient removal of endotoxin from patients' blood is very important in clinical medicine. The purpose of this study was to determine the endotoxin adsorption capacities of commercial endotoxin adsorbers for endotoxin removal in buffer solution, protein solution, serum and heparinized plasma; some of these were also characterized in whole blood. The tested LPS adsorbers were Toraymyxin® PMX-20R, Alteco® LPS Adsorber, DEAE-Sepharose, Polymyxin B-Agarose, and EndoTrap® red.

METHODS

The adsorber materials were tested in buffer and protein solutions spiked with fluorescently labeled LPS (100 ng/ml). Additionally, batch tests with LPS-spiked serum, heparinized plasma and whole blood were performed with an LPS concentration of 5 ng/ml. Additionally, the washing solutions of the two tested Polymyxin B (PMB)-based adsorbers were analyzed for PMB release to determine if the resulting LPS inactivation was caused by PMB leakage.

RESULTS

The results show that DEAE-Sepharose was most effective in LPS adsorption. Of the other tested endotoxin removal materials, only the PMB-based adsorbers were able to reduce the LPS activity. However, we were able to show that the reduction in LPS activity was caused by desorbed PMB, which inactivates endotoxins.

CONCLUSIONS

None of the adsorbents that were tested in this study showed promising results for potential use in extracorporeal blood purification.

Prognostic value of endotoxin activity assay in patients with severe sepsis after cardiac surgery

Background

To evaluate the prognostic value of endotoxin activity assay (EAA) in adult patients with suspected or proven severe sepsis after cardiac surgery

Methods

Blood samples taken from 81 patients immediately after the diagnosis of severe sepsis were tested with the EAA. Patients were divided into 3 groups: low (<0.4, n = 20), moderate (0.4-0.59, n = 35) and high (≥0.6, n = 26) EAA levels.

Results

Gram-negative bacteraemia was found in 19/55 (35%) of cases with ЕАА <0.6 and in 11/26 (42%) of cases with higher ЕАА, p = 0.67. Mortality at 28 days in Groups 1, 2 and 3 was 20%, 43% and 54%, respectively. Patients with an EAA higher than 0.65 had a higher 28-day mortality than those with lower EAA values (18/26 – 69% vs. 19/55 – 34.5%; p = 0.0072). ROC analysis for the prediction of 28-day mortality revealed an AUC for APACHE II scores, EAA and PCT of 0.81, 0.73 and 0.66, respectively.

Conclusions

EАА might be useful for recognising patients who have an increased risk of mortality due to severe sepsis.

A new endotoxin adsorber in septic shock: observational case series

AIMS

Effects of a new endotoxin adsorber on the length of noradrenaline (NA) treatment, LPS (lipopolysaccharide) levels and SOFA (sequential organ failure assessment) scores in septic shock were evaluated.

METHODS

Two-hour hemoperfusion with LPS adsorber was initiated in patients with septic shock and endotoxemia. Controls were matched for age, focus and severity of illness.

RESULTS

Adsorption treatment (n = 9) exhibited a significant decrease in EAA (endotoxin activity assay) activity (0.55 [0.44-0.68] vs. 0.25 [0.13-0.41], p = 0.019) and NA infusion rate (0.217 μg/kg/min [0.119-0.0508] vs. 0 μg/kg/min [0-0.09], p = 0.026) from pretreatment to 24 h post-treatment. The median decrease in SOFA scores from pretreatment to 24 h was 3.0 points (1.5-4.5), p = 0.002. Duration of NA infusion was significantly shorter compared to controls (39 h [31-48] vs. 54 h [43-151], p = 0.03).

CONCLUSIONS

LPS adsorber treatment was associated with a decrease in NA dose, decrease in SOFA scores and LPS concentrations.

Endotoxemia related to cardiopulmonary bypass is associated with increased risk of infection after cardiac surgery: a prospective observational study

Introduction

Previous studies have documented a high frequency of endotoxemia associated with cardiopulmonary bypass (CPB). Endotoxemia may be responsible for some of the complications associated with cardiac surgery. The purpose of the study was to examine the prevalence of endotoxemia during cardiopulmonary bypass supported aortocoronary bypass grafting surgery (ACB) using a new assay, the Endotoxin Activity Assay (EAA), and explore the association between endotoxemia and post-operative infection.

Methods

The study was a single center prospective observational study measuring EAA during the perioperative period for elective ACB. Blood samples were drawn at induction of anesthesia (T1), immediately prior to release of the aortic cross-clamp (T2), and on the first post-operative morning (T3). The primary outcome was the prevalence of endotoxemia. Secondary outcomes assessed included infection rates, intensive care unit (ICU) and hospital length of stay. An EAA of < 0.40 units was interpreted as "low", 0.41 to 0.59 units as "intermediate", and ≥0.60 units as "high".

Results

A total of 57 patients were enrolled and 54 patients were analyzable. The mean EAA at T1 was 0.38 +/- 0.14, at T2 0.39 +/- 0.18, and at T3 0.33 +/- 0.18. At T2 only 13.5% (7/52) of patients had an EAA in the high range. There was a positive correlation between EAA and duration of surgery (P = 0.02). In patients with EAA ≥0.40 at T2, 26.1% (6/23) of patients developed post-operative infections compared to 3.5% (1/29) of those that had a normal EAA (P = 0.0354). Maximum EAA over the first 24 hours was also strongly correlated with risk of post-operative infection (P = 0.0276).

Conclusions

High levels of endotoxin occur less frequently during ACB than previously documented. However, endotoxemia is associated with a significantly increased risk of the development of post-operative infection. Measuring endotoxin levels during ACB may provide a mechanism to identify and target a high risk patient population.

Endotoxin removal devices for the treatment of sepsis and septic shock

A substantial body of experimental and clinical evidence suggests that neutralising or removing lipopolysaccharide endotoxin would be an effective adjunctive approach to the management of Gram-negative sepsis. Polymyxins are a group of cyclic cationic polypeptide antibiotics. Although they have useful antimicrobial activity against Gram-negative bacteria, their clinical use has been limited because of toxicity. However, in addition to their antimicrobial property, polymyxins can bind to and neutralise endotoxin. Thus, investigators have explored the possibility of using polymyxin bound to a solid-phase carrier for specific haem-adsorption in patients with sepsis, thereby retaining the lipopolysaccharide-binding properties but minimising systemic toxic effects. This system has been widely used in Japan for many years, but convincing clinical evidence of efficacy is lacking. A recent Italian study has some promising data. Although polymyxin has been the principal agent used to explore this approach, other molecules have the ability to bind endotoxin, and some of these have very recently been proposed as the basis for other endotoxin-removal devices. The available evidence is reviewed to assess the potential use of such devices in clinical practice.

Up-regulation of the Apo/Fas (CD95) complex on neutrophils harvested during cardiac surgery: distinct findings in patients operated on with or without the use of cardiopulmonary bypass

Aims: In a group of patients undergoing cardiac surgery performed both with (“on-pump”) and without the use (“offpump”) of cardiopulmonary bypass (CPB), we studied the changes of neutrophil membrane apoptosis-inducing complex Apo/Fas.

Methods: Expression of Apo/Fas (CD95) on leukocytes was evaluated by flow cytometry.

Results: In “on-pump” patients, we found an increase in the expression of CD95 median intensity fluorescence (MFI) on granulocytes from a baseline level median=56, (Q 1=45.5, Q3=64) to a median=88, (Q1=62, Q 3=109.5; p<0.01) at the 3rd postoperative day and median=74, (Q1=63, Q3=84.5; p<0.01) at the 7th postoperative day. In “off-pump” patients, granulocyte CD95 MFI was median=55, (Q1=51, Q3=84) before surgery. The significant increase was found on the 3rd postoperative day only; median=90, (Q 1=66; Q3=98; p<0.05). A similar pattern in the CD95 expression was also found if percentage changes of granulocyte CD95 MFI were followed. Moreover, the significantly increased Apo/Fas expression expressed as a percentage change of CD95 MFI was found in “on-pump” patients compared to “off-pump” patients, both at the 3rd postoperative day (p<0.05) and at the 7th postoperative day (p<0.01).

Conclusions: This is the first direct evidence of increasing densities of the Apo/Fas complex on neutrophils in cardiac surgical patients.