Continuous arteriovenous hemofiltration therapy for Staphylococcus aureus-induced septicemia in immature swine

Adjunctive immunotherapeutic agents in patients with sepsis and septic shock: a multidisciplinary consensus of 23

BACKGROUND

In the last decades, several adjunctive treatments have been proposed to reduce mortality in septic shock patients. Unfortunately, mortality due to sepsis and septic shock remains elevated and NO trials evaluating adjunctive therapies were able to demonstrate any clear benefit. In light of the lack of evidence and conflicting results from previous studies, in this multidisciplinary consensus, the authors considered the rational, recent investigations and potential clinical benefits of targeted adjunctive therapies.

METHODS

A panel of multidisciplinary experts defined clinical phenotypes, treatments and outcomes of greater interest in the field of adjunctive therapies for sepsis and septic shock. After an extensive systematic literature review, the appropriateness of each treatment for each clinical phenotype was determined using the modified RAND/UCLA appropriateness method.

RESULTS

The consensus identified two distinct clinical phenotypes: patients with overwhelming shock and patients with immune paralysis. Six different adjunctive treatments were considered the most frequently used and promising: (i) corticosteroids, (ii) blood purification, (iii) immunoglobulins, (iv) granulocyte/monocyte colony-stimulating factor and (v) specific immune therapy (i.e. interferon-gamma, IL7 and AntiPD1). Agreement was achieved in 70% of the 25 clinical questions.

CONCLUSIONS

Although clinical evidence is lacking, adjunctive therapies are often employed in the treatment of sepsis. To address this gap in knowledge, a panel of national experts has provided a structured consensus on the appropriate use of these treatments in clinical practice.

The Techniques of Blood Purification in the Treatment of Sepsis and Other Hyperinflammatory Conditions

Even in the absence of strong indications deriving from clinical studies, the removal of mediators is increasingly used in septic shock and in other clinical conditions characterized by a hyperinflammatory response. Despite the different underlying mechanisms of action, they are collectively indicated as blood purification techniques. Their main categories include blood- and plasma processing procedures, which can run in a stand-alone mode or, more commonly, in association with a renal replacement treatment. The different techniques and principles of function, the clinical evidence derived from multiple clinical investigations, and the possible side effects are reviewed and discussed along with the persisting uncertainties about their precise role in the therapeutic armamentarium of these syndromes.

Blood Purification Techniques for Sepsis and Septic AKI

Sepsis is the primary cause of acute kidney injury in critically ill patients. During the past decades, several extracorporeal blood purification techniques have been developed for sepsis and sepsis-induced acute kidney injury management. These therapies could act on both the infectious agent itself and the host immune response. In this article, we review the available literature discussing the different extracorporeal blood purification techniques, including high-volume hemofiltration, cascade hemofiltration, hemoperfusion, coupled plasma filtration adsorption, plasma exchange, and specific optimized renal replacement therapy membranes.

Obstructive jaundice in a patient with polycystic liver disease complicated with polycystic kidney and polycystic lung: A case report

RATIONALE

Polycystic liver disease (PLD) is an autosomal-dominant disorder that is commonly associated with autosomal-dominant polycystic kidney disease (PKD) but rarely complicated with polycystic lung. Here, we report the first case of severe obstructive jaundice caused by multiple liver cysts in a patient with PLD complicated by PKD and polycystic lung.

PATIENT CONCERNS

A 72-year-old man with a history of PLD complicated with polycystic kidney presented with progressive jaundice, hematuria, poor appetite, nausea, and weight loss since 3 months.

DIAGNOSIS

PLD complicated with PKD and polycystic lung was identified using computed tomography, and obstructive jaundice was identified using magnetic resonance imaging and magnetic resonance cholangiopancreatography.

INTERVENTIONS

The patient could not undergo surgery, and was therefore treated with combined bilirubin adsorption and continuous veno-venous hemofiltration.

OUTCOMES

The patient's symptoms and laboratory findings improved after bilirubin adsorption and continuous veno-venous hemofiltration. Unfortunately, the patient was unable to continue the treatment due to financial reasons, and died of shock most likely due to cyst rupture.

LESSONS

Imaging examination of the lungs is necessary for patients with PLD. Although infrequent, jaundice can occur in these patients and cause severe hyperbilirubinemia. When surgery is contraindicated, blood purification may serve as an alternative treatment for patients with PLD-related obstructive jaundice.

The outcome of critically ill elderly patients with severe acute renal failure treated by continuous hemodiafiltration

Objectives

To study the outcome of critically ill elderly patients with severe acute renal failure managed by continuous hemodiafiltration.

Design

Prospective study.

Setting

Intensive Care Unit of tertiary institution

Patients

Seventy-two consecutive critically ill patients of 65 years or older admitted to the ICU with severe acute renal failure. Seventy similar control patients of age < 65 years.

Intervention

Treatment of all patients with continuous hemodiafiltration. Measurements and main results: Safety and effectiveness of therapy were assessed. Main outcome measures were duration of oliguria, of ICU stay, and hospital stay for survivors, and survival to ICU discharge and to hospital discharge. Mean APACHE II score on admission was 29.8 (95% confidence interval: 28.5 to 31.1) and mean organ failure score prior to initiation of continuous hemodiafiltration was 3.9 (95% confidence interval: 3.6 to 4.2). Sepsis was present in 51 cases (70.8%) and bacteremia or fungemia in 24 (33.3%). Fifty-three (73.6%) required mechanical ventilation for > 3 days. Vasopressor drugs were used in 65 (90.2%). Continuous hemodiafiltration controlled azotemia in all patients and was only associated with minor complications. Thirty-four patients (47.2%) survived to ICU discharge and 30 (41.6%) to hospital discharge. Among survivors, duration of oliguria was 11.6 days (95% confidence interval: 9.1 to 14.1), mean duration of ICU stay 8.6 days (95% confidence interval: 6.1 to 11.) and mean duration of hospital stay 33.1 days (95% confidence interval: 28.8 to 37.4). No statistically significant difference in survival was found when these patients were compared to a control group of similar but younger patients who also received ICU care and continuous hemodiafiltration for the treatment of severe acute renal failure.

Conclusions

A greater than 40% survival was achieved in critically ill elderly patients with severe acute renal failure by the use of continuous hemodiafiltration. These patients had an in hospital survival comparable to that of younger patients. These findings support an aggressive renal replacement approach in such patients and suggest that continuous hemodiafiltration may be ideally suited to their management.

Super High Flux Hemodialysis at High Dialysate Flows: An Ex Vivo Assessment

Background and objectives

The removal of cytokines by standard hemofiltration is limited. Super high flux membranes may significantly improve removal even when used in dialysis mode. We sought to measure cytokine clearance using a large surface super high-flux membrane and a standard hemodialysis setting.

Setting

ICU laboratory of a tertiary institution.

Subjects

Six healthy volunteers.

Methods

Blood form healthy volunteers was incubated for 4 hours with E. coli endotoxin to stimulate cytokine production. Cytokine containing blood was then circulated through a dialysis circuit at 3 different dialysate flow rates. Blood and dialysate were sampled for cytokine and albumin measurements and calculation of clearances.

Results

Super high-flux dialysis achieved high median cytokine clearances (IL-1 clearance of 106 ml/min, IL-6 clearance of 66.8 ml/min, IL-8 clearance of 61.7 ml/min and TNF clearance of 36.1 ml/min). Increasing dialysate flow rate from 300 to 500 ml/min did not significantly increase cytokine clearances. Albumin clearances however were between 2.7 and 5.4 ml/min.

Conclusions

Cytokine dialysis is feasible at high dialysate flow rates yielding high cytokine clearances. Albumin loss, however, is appreciable and may require separate supplementation in the clinical setting.

Extracorporeal Blood Treatment (EBT) Methods in SIRS/Sepsis

Background

Extracorporeal blood purification treatment (EBT) methods have been used in the treatment of experimental and human SIRS/Sepsis in a variety of settings and with variable reports of efficacy and safety. Their role in the management of SIRS/Sepsis remains controversial.

Objectives

To develop consensus statements regarding important aspects of research, practice and technical management concerning EBT.

Methods

Systematic review of published study. Evidence-based grading of information available. Consensus development regarding fundamental questions about EBT.

Results

Consensus was achieved on all questions posed during the conference. It was agreed that there is currently a clear biological rational for EBT in SIRS and Sepsis. It was agreed that conventional CVVH has sufficiently been shown not to be effective in SIRS/Sepsis in the absence of concomitant ARF and that other therapies such as plasmapheresis or high-volume hemofiltration or coupled plasma filtration adsorption appear more promising and should be tested in multicentre randomized controlled trials. Patients with ARF and SIRS/Sepsis should be treated differently from those with ARF alone even though current practice in this field is not well known. Patients with refractory septic shock should be considered for EBT. Appropriate end points for clinical trials can be defined and chosen according to the goals of the trial. Different technologies exist for EBT and better understanding of the merits and safety of each is needed as well as better standardization of methodology and dose.

Conclusions

Broad consensus can be achieved on several aspects of EBT and can be used to inform clinical practice and to help guide the establishment of a future research agenda.

Continuous hemoadsorption with a cytokine adsorber during sepsis - a review of the literature

Sepsis is a well-recognized healthcare issue worldwide, ultimately resulting in significant mortality, morbidity and resource utilization during and after critical illness. In its most severe form, sepsis causes multi-organ dysfunction that produces a state of critical illness characterized by severe immune dysfunction and catabolism. Sepsis induces the activation of complement factor via 3 pathways and the release of inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin-1beta (IL-1β), resulting in a systemic inflammatory response. The inflammatory cytokines and nitric oxide release induced by sepsis decrease systemic vascular resistance, resulting in profound hypotension. The combination of hypotension and microvascular occlusion results in tissue ischemia and ultimately leads to multiple organ failure. Several clinical and experimental studies have reported that treatment using adsorption of cytokines is beneficial during endotoxemia and sepsis. This review article analyzes the efficacy of CytoSorb® adsorber in reducing the inflammatory response during sepsis. The CytoSorb® adsorber is known to have excellent adsorption rates for inflammatory cytokines such as IL-1β, IL-6, IL-8, IL-10, and TNF-α. Studies have demonstrated that treatment with cytokine adsorbing columns has beneficial effects on the survival rate and inflammatory responses in animal septic models. Additionally, several cases have been reported in which treatment with cytokine adsorbing columns is very effective in hemodynamic stabilization and in preventing organ failure in critically ill patients. Although further investigations and clinical trials are needed, treatment with cytokine adsorbing columns may play an important role in the treatment of sepsis in the near future.

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.

Blood hemoperfusion with resin adsorption combined continuous veno-venous hemofiltration for patients with multiple organ dysfunction syndrome

BACKGROUND

Blood hemoperfusion with resin adsorption can clean larger molecules that exceed the molecular weight cutoff of combined continuous veno-venous hemofiltration (CVVH). Hence blood hemoperfusion with resin adsorption combined CVVH (HP+CVVH) has higher ability of mediator clearance, and can improve clinical outcomes in theory. This study aimed to investigate the effect of blood hemoperfusion with resin adsorption combined continuous veno-venous hemofiltration (HP+CVVH) on plasm cytokines like TNF-α, IL-1β, IL-6, cellular immunity and prognosis in patients with multiple organ dysfunction syndrome (MODS).

METHODS

This was a prospective, randomized clinical trial. A total of 30 patients who had been diagnosed with MODS were enrolled in this study. Patients were randomly allocated to routine treatment+HP+CVVH group (treatment group) and routine treatment+only CVVH group (control group). In the treatment group, patients received blood hemoperfusion with resin adsorption for 2 hours, and then received CVVH for 10 hours every day. In the control group, patients received CVVH for 12 hours only every day. The patients in the two groups received blood purification therapy for three days. The plasma of patients in the treatment group was obtained at 0, 2, 12, 24, 26, 36, 48, 50, 60 hours, 5th day, 7th day and 10th day, respectively. The plasma of patients in the control group was obtained at 0, 12, 24, 36, 48, 60 hours, 5th day, 7th day and 10th day, respectively. APACHE II score, T-lymphocytes subpopulations, blood lactate acid concentration, heart rate, breathing rate, and oxygenation index were observed.

RESULTS

Plasma cytokines like TNF-α, IL-1β, IL-6 decreased markedly after HP (P<0.01); T-lymphocytes subpopulations CD3+, CD4+, CD8+, CD4+/CD8+ increased after HP+CVVH or only CVVH. The plasma concentrations of TNF-α, IL-1β and IL-6 in the two groups were not markedly different at 12, 36, and 50 hours. But on the 5th day, the plasma concentrations of TNF-α, IL-1β and IL-6 in the treatment group were lower than those in the control group (P<0.05). On the 28th day, 5 patients died in the treatment group, and 6 patients in the control group.

CONCLUSIONS

Both HP+CVVH and CVVH can clean plasma cytokines like TNF-α, IL-1β, and IL-6, and improve cellular immunity and clinical symptoms and signs of patients. Compared with only CVVH, the plasma concentrations of TNF-α, IL-1β and IL-6 were lower on the 5th day, and patients have an increased survival rate on the 28 day in the HP+CVVH group.

High-volume hemofiltration for septic acute kidney injury: a systematic review and meta-analysis

Introduction

High-volume hemofiltration (HVHF) is an attractive therapy for the treatment of septic acute kidney injury (AKI). Small experimental and uncontrolled studies have suggested hemodynamic and survival benefits at higher doses of HVHF than those used for the high-intensity arms of the RENAL and ATN studies. Our aim was to evaluate the effects of high-volume hemofiltration (HVHF) compared with standard-volume hemofiltration (SVHF) for septic AKI.

Methods

A systematic review and meta-analysis of publications between 1966 and 2013 was performed. The review was limited to randomized-controlled trials that compared HVHF (effluent rate greater than 50 ml/kg per hour) versus SVHF in the treatment of sepsis and septic shock. The primary outcome assessed was 28-day mortality. Other outcomes assessed were recovery of kidney function, lengths of ICU and hospital stays, vasopressor dose reduction, and adverse events.

Results

Four trials, including 470 total participants, were included. Pooled analysis for 28-day mortality did not show any meaningful difference between HVHF compared with SVHF (OR, 0.76; 95% CI, 0.45 to 1.29). No included studies reported statistically significant differences between groups for any of the secondary outcomes. Adverse events, including hypophosphatemia and hypokalemia, were more commonly observed in HVHF-treated patients, although reporting was inconsistent across studies.

Conclusions

Insufficient evidence exists of a therapeutic benefit for routine use of HVHF for septic AKI, other than on an experimental basis. Given the logistic challenges related to patient recruitment along with an incomplete understanding of the biologic mechanisms by which HVHF may modify outcomes, further trials should focus on alternative extracorporeal therapies as an adjuvant therapy for septic AKI rather than HVHF.

Toll-like receptor kinetics in septic shock patients: a preliminary study

The aim of this study is to evaluate some inflammatory parameter changes in septic shock patients and their possible correlation with clinical outcome, in particular when continuous veno-venous hemofiltration (CVVH) treatment is required. Considering the objective difficulty in enrolling this kind of patient, a preliminary study was initiated on seventeen septic shock patients admitted to a medical and surgical ICU. The mRNA expression of Toll-like receptor (TLR)-1, TLR-2, TLR-4, TLR-5, TLR-9, TNFα, IL-8 and IL-1β was assessed, the plasmatic concentrations of IL-18, IL-2, IL-10 and TNFα were measured on the day of sepsis diagnosis and after 72 h. In those patients who developed acute renal failure unresponsive to medical treatment and who underwent CVVH treatment the same parameters were measured every 24 h during CVVH and after completion of the treatment. On sepsis diagnosis, gene expression of TLRs was up-regulated compared to the housekeeping gene in all the patients. After 72 h, in 35% of the patients a down-regulation of these genes was found compared to day 1, but it was not associated with a reduction of cytokine serum levels or improved clinical signs, better outcome or reduced mortality. After high volume hemofiltration treatment, cytokine serum levels and TLR expression were not significantly modified. In conclusion, considering the not numerous number of cases, from our preliminary study, we cannot certainly correlate TLR over-expression in septic shock patients with severity or outcome scores.

Effect of the intensity of continuous renal replacement therapy in patients with sepsis and acute kidney injury: a single-center randomized clinical trial

INTRODUCTION

Acute kidney injury (AKI) is a major complication in patients with sepsis and is an independent predictor of mortality. However, the optimal intensity of renal replacement therapy for such patients is still controversial.

METHODS

From 1 January 2004 to 30 September 2009, we randomly assigned 280 patients with sepsis and AKI to continuous renal replacement therapy by high-volume hemofiltration (50 mL/kg/h, HVHF) or extra high-volume hemofiltration (85 mL/kg/h, EHVHF). The primary study outcome was death from any cause within 28, 60 and 90 days. Results were analyzed by univariate and multivariate methods and by Kaplan-Meier survival curves.

RESULTS

A total of 141 patients were given EHVHF and 139 were given HVHF. The two groups had similar baseline characteristics and received treatment for an average of 9.38 days (EHVHF group) and 8.88 days (HVHF group). There were no significant differences between the groups in number of deaths at 28, 60 or 90 days. There were also no differences between the groups in renal outcome of survivors at 90 days. Multivariate analysis indicated that inotropic support by norepinephrine, time in hospital of >7 days, blood platelet count <8 × 10(9)/L, Acute Physiological and Chronic Health Evaluation (APACHE) II score >25, total bilirubin >100 μmol/L, prothrombin time >18 s, serum creatinine <250 μmol/L and blood urea nitrogen >20 mmol/L were independent risk factors for death at 90 days after initiation of renal replacement therapy.

CONCLUSIONS

In patients with sepsis and AKI, increasing the intensity of renal replacement therapy from 50 (HVHF) to 85 mL/kg/h (EHVHF) had no effect on survival at 28 and 90 days.

Clinical review: blood purification for sepsis

Sepsis is the primary cause of death in the intensive care unit. Extracorporeal blood purification therapies have been proposed for patients with sepsis in order to improve outcomes since these therapies can alter the host inflammatory response by non-selective removal of inflammatory mediators or bacterial products or both. Recent technological progress has increased the number of techniques available for blood purification and their performance. In this overview, we report on the latest advances in blood purification for sepsis and how they relate to current concepts of disease, and we review the current evidence for high-volume hemofiltration, cascade hemofiltration, hemoadsorption, coupled plasma filtration adsorption, high-adsorption hemofiltration, and high-cutoff hemofiltration/hemodialysis. Promising results have been reported with all of these blood purification therapies, showing that they are well tolerated, effective in clearing inflammatory mediators or bacterial toxins (or both) from the plasma, and efficacious for improvement of various physiologic outcomes (for example, hemodynamics and oxygenation). However, numerous questions, including the timing, duration, and frequency of these therapies in the clinical setting, remain unanswered. Large multicenter trials evaluating the ability of these therapies to improve clinical outcomes (that is, mortality or organ failure), rather than surrogate markers such as plasma mediator clearance or transient improvement in physiologic variables, are required to define the precise role of blood purification in the management of sepsis.

[High volume hemofiltration in septic shock]

Severe sepsis and septic shock are conditions associated with high morbidity and mortality. The disproportionate release of pro-inflammatory and anti-inflammatory mediators caused by the septic insult is the promoter of multiple organ dysfunction. Conventional hemodialysis, hemofiltration or a combination of both can be a good option to replace the deteriorating renal function in critically ill patients by the removal of nitrogen compounds (small molecules). However, this "renal dose" is insufficient for the removal of inflammatory mediators (medium molecules), and therefore contributes little to the cardiovascular stabilization of patients with septic shock. In this setting, a higher dose of ultrafiltration (> 50 ml/kg/h) or "septic dose" may be needed. In this review article, we have analyzed the clinical and pathophysiological rationale for the use of high volume hemofiltration in patients with septic shock.

Cardiac contractility during hemofiltration in an awake model of hyperdynamic endotoxemia

BACKGROUND

To determine whether continuous veno-venous hemofiltration can ameliorate hemodynamic instability and left ventricular (LV) dysfunction by reducing circulating plasma mediators, the authors used the LV end-systolic elastance (Ees) as a contractility index, in an awake swine model simulating human hyperdynamic endotoxemia.

METHODS

Nineteen instrumented pigs were divided into a control group (CTRL, n = 7), a hemofiltration (HF, n = 7) group, and an extracorporeal circuit (ECC, n = 5) only group. All animals received intravenous E. coli endotoxin (10 microg x kg x h) and resuscitation in a common regimen for 24 hours. Hemofiltration was started 30 minutes after initiation of endotoxemia and continued until the end of the experiment.

RESULTS

: Ees was maintained at baseline levels in the HF group, whereas a progressive decrease of Ees was found in both the CTRL and the ECC groups. Cardiac output was significantly higher in the HF group than the CTRL group. There was no significant difference between the groups in plasma catecholamines.

CONCLUSION

We conclude that hemofiltration prevented LV impairment.

Extracorporeal cell therapy with granulocytes in a pig model of Gram-positive sepsis

OBJECTIVES

Granulocyte transfusions have been used to treat immune cell dysfunction in sepsis. As granulocyte transfusions can trigger tissue injury via local effects of neutrophils, we hypothesized that extracorporeal treatment of plasma using granulocytes would prove beneficial while having less side effects.

DESIGN

Prospective controlled three-armed animal study.

SETTING

Research laboratory.

SUBJECTS

Twenty-one female immature pigs (7.5-12 kg, 7-9 weeks old).

INTERVENTIONS

Three groups of spontaneously breathing, sedated pigs (n = 7 each) received an intravenous lethal dose of live Staphylococcus aureus over 1 hour. Although group I had no specific treatment (control), group II and III were subsequently treated for 4 hours with an extracorporeal device containing either no cells (sham control, group II) or human cell line-derived granulocytic cells (group III). Survival time and physiologic, biochemical, and hematologic parameters were monitored for 7 days.

MEASUREMENTS AND MAIN RESULTS

All animals of group I died during the observation time (mean survival time: 70 hours). In group II, two of seven and in group III, six of seven animals survived the observation time (mean survival: 75 and 168 hours, respectively). Survival differences were significant between group I and III (p < 0.001) and between group II and III (p < 0.05) but not between group I and II (p = 0.43). Furthermore, group differences in bacterial blood concentrations, differential blood count, blood gases, lactate, and interleukins were observed. The extracorporeal cell treatment was well tolerated by the animals.

CONCLUSIONS

Extracorporeal therapy with granulocytic cells significantly improved survival in a pig model of sepsis. Further studies with this approach are encouraged.

Hemofiltration in sepsis and systemic inflammatory response syndrome: the role of dosing and timing

INTRODUCTION

The benefit of hemofiltration (HF) as an adjunctive treatment of sepsis or the systemic inflammatory response syndrome (SIRS) in critically ill patients is a subject of severe debate. Firm conclusions on this subject are hampered by the heterogeneity in study populations and HF treatments, and the lack of adequately sized randomized controlled clinical trials. The aim of this review was to determine the importance of ultrafiltration dose and timing on the physiologic and clinical effects of HF in sepsis and SIRS. In addition, we discuss the issue of filter pore size.

METHODS

Literature search was done in Embase and PubMed database for animal and human studies.

RESULTS

Animal studies suggest beneficial effects of HF on hemodynamics; gas exchange; sepsis-induced immunoparalysis; histology of gut, lung, and kidney; and (short-term) survival. These effects were more prominent with "very high" ultrafiltrate rates (> or =100 mL/kg per hour) and early initiation of HF (ie, before or very early after the septic challenge). Three small randomized studies and 3 observational studies in patients with sepsis or SIRS show beneficial effects of short-term or pulse HF using very high ultrafiltrate rates and/or early initiation of HF on physiologic endpoints and survival. However, the studies were underpowered for survival. The first observations of high permeability HF (pore size, about 10 nm; in vitro cutoff, 100 kd) are promising, but so far, it has not been sufficiently examined to allow strong conclusions.

CONCLUSION

Human and animal studies suggest that early initiation and high ultrafiltrate volumes are determinants of the beneficial physiologic and clinical effect of HF in sepsis and SIRS. As yet, the evidence in humans is too low to recommend HF as an adjunctive therapy for critically ill patients with sepsis or SIRS. Regarding the many uncertainties about optimal volume (high or very high) and type of membrane, clinical studies should first focus on endpoints as recovery from organ failure and length of treatment before survival studies are started.

Early hemodynamic improvement is a prognostic marker in patients treated with continuous CVVHDF for acute renal failure

We examined whether hemodynamic improvement after high-flow hemofiltration predicts survival in patients treated with standard continuous renal replacement therapy (CRRT). This was a prospective, observational cohort study of 169 patients, measuring the mean arterial pressure (MAP) and norepinephrine (NE) dosage before and 24 hours after CRRT. Responders were defined as having a 20% reduction in NE dosage or a 20% rise in MAP with no increase in NE, compared with nonresponders. Patients were considered to be unstable if they were receiving NE or their MAP was lower than 60 mm Hg before CRRT. Of the 169 patients, 68% were men; mean age was 53.8 years (52.7 to 54.9), with a mean Acute Physiology and Chronic Health Evaluation (APACHE) II at admission of 21.8 (21.2 to 22.3), of whom 114 were unstable at the start of CRRT. Overall mortality rate 15 days after the end of CRRT was 54.3% (57.7% in stable vs. 52.9% in unstable patients, p = NS). There were 99 responders and 70 nonresponders, the only differences being NE dosage (higher in responders, p < 0.01) and mortality rate (responders 30% vs. nonresponders 74.7%, p < 0.001). In unstable patients, mortality rate was 30% in responders versus 87% in nonresponders (p < 0.001) (72% sensitivity and 86% specificity for predicting death). Logistic regression analysis showed that the only variables associated with death were APACHE II at admission (OR, 1.06; 95% CI, 1.0 to 1.12), percent creatinine decrease (OR, 0.98; CI, 0.96 to 1.0), and lack of hemodynamic response to CRRT (OR, 7.04; CI, 3.3 to 15.02). Hemodynamic improvement after 24-hour CRRT is a strong predictor of survival.

Endotoxin adsorption therapy for septic shock using polymyxin B-immobilized fibers (PMX): evaluation by high-sensitivity endotoxin assay and measurement of the cytokine production capacity

Because of its low sensitivity, the conventional measurement method for endotoxin (ET) is not the most appropriate for monitoring the effect of ET adsorption therapy. Thus, the efficacy of ET adsorption therapy was investigated using a newly developed high-sensitivity ET assay method. The changes in the cytokine production capacity of whole blood were also examined. We treated 24 peritonitis patients who had developed postoperative septic shock with ET adsorption therapy using a column of polymyxin B-immobilized fibers (PMX) and their serum ET levels were measured using the high-sensitivity ET assay based on the kinetic turbidimetric Limulus assay. In addition, the changes in the tumor necrosis factor-(TNF-alpha) production capacity of whole blood following lipopolysaccharide (LPS) stimulation and clinical outcome in the study patients were also examined. The 28-day mortality rate was 12%. PMX-direct hemoperfusion (PMX-DHP) was associated with elevation of the mean arterial pressure and urine output, reduction in the mean dose requirement of vasopressor agents, and recovery from the shock state in all the patients. The PaO2/FIO2 ratio also showed significant improvement. Using the high-sensitivity ET assay, ET was detected in the blood of 20 out of the 24 patients (80%) before the PMX-DHP, and a significant reduction in the ET level was noted after the PMX-DHP. The TNF-alpha production capacity of whole blood, which was found to be lower in the septic shock patients than in healthy subjects, was significantly increased after PMX-DHP. Elimination of ET by PMX-DHP in septic shock patients was confirmed by the high-sensitivity ET assay. PMX-DHP is thus considered to be a useful adjuvant therapeutic technique in the treatment of septic shock. Also, PMX-DHP might alleviate the immunosuppression associated with severe sepsis.

High-volume hemofiltration in septic shock

In the past decade we have learned a lot about the pathophysiology of septic shock. A lot of experimental research has been performed in vitro and in vivo, showing that hemofiltration can improve hemodynamics and survival. With modern machines, hemofiltration is becoming a sepsis treatment in patients.

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

BACKGROUND

As removal of pro-inflammatory cytokines is limited in conventional diffusive or convective extracorporeal therapies, we studied in two polysulphone membranes with an industrial albumin sieving coefficient of 0.05 (Type A) and 0.13 (Type B) cytokine (IL-6, IL-8, IL-1beta, IL-1ra, TNF-alpha) and plasma protein (albumin, cystatin C, total proteins) permeability profiles. Based on the convective membrane permeability, we evaluated in vitro the dialytic modality that could provide an acceptable balance between high cytokine and low albumin clearances.

METHODS

Cytokine and plasma protein sieving coefficient (SC) and clearance were studied in (i) post-dilutional haemofiltration mode at 20% fixed ultrafiltration rate; (ii) haemodialysis mode (dialysate flow rate of 3 and 5 l/h); and (iii) haemodiafiltration mode (dialysate flow rate of 3 or 5 l/h with 0.5 l/h of ultrafiltrate).

RESULTS

In haemofiltration mode both Type A and Type B haemodialysers at QB 150 ml/min exhibited similar median SC nearly up to 1 for IL-1beta and IL-1ra, at about 0.6 for IL-6, 0.4 for IL-8 and 0.7 for TNF-alpha, with clearance values ranging from 15 to 30 ml/min. SC were independent of blood flow and were stable throughout the whole experiment. Albumin SC was higher in Type B than in Type A and rapidly decreased from 0.2 to 0.02 and from 0.5 to 0.04 within 3 h for haemodialyser Types A and B, respectively. Cytokine SC was lower in haemodialysis than in haemodiafiltration and haemofiltration mode, and by increasing dialysate flow from 3 up to 5 l/h in both haemodialysis and haemodiafiltration mode, SC for all tested cytokines decreased. However, at 5 l/h clearances were not different or were higher, since increased amounts of dialysate outlet compensated for the decreased SC. Albumin clearances in haemodialysis and haemodiafiltration mode after 360 min at 5 l/h were 0.81 and 0.91 ml/min, respectively.

CONCLUSIONS

Our studies show that a mixed convective and diffusive technique ensures high cytokine clearances with an acceptable loss of albumin.

Pulse high volume hemofiltration

The sepsis syndrome is the most common cause of acute renal failure and multiple organ dysfunction in critically ill subjects and continues to have an alarmingly high mortality. Normal immune homeostasis is interrupted by a complex storm of inflammatory mediators responsible for the deleterious effects. Extracorporeal blood purification techniques can confer benefits in sepsis by proven non-specific removal of these mediators (pro- or anti-inflammatory), and provide a logical and adequate approach to treat this syndrome. High volume hemofiltration (HVHF) has had the most dramatic effect conferring benefits in hemodynamics, reduction in vasopressor doses and improvement in survival. "Pulse HVHF" is the latest approach which may offer the most efficient results: a daily schedule of 6-8 hours followed by standard CVVH. This paper describes the rationale and potential of this technique. Reliability and tolerance of this technique and biological effects are described.

Hemoadsorption removes tumor necrosis factor, interleukin-6, and interleukin-10, reduces nuclear factor-kappaB DNA binding, and improves short-term survival in lethal endotoxemia

OBJECTIVES

Previous studies have shown that inflammatory mediators can be removed from the circulation with hemofiltration and that adsorption plays an important role. Because adsorptive capacity of hollow-fiber dialyzers is limited, we sought to determine whether hemoadsorption using high surface area beads would result in greater mediator removal and improved survival in experimental sepsis.

DESIGN

Randomized controlled laboratory experiment.

SETTING

University laboratory.

SUBJECTS

Sixty-six adult Sprague-Dawley rats.

INTERVENTIONS

We conducted two ex vivo and two in vivo experiments. For in vivo experiments, we administered Escherichia coli endotoxin (20 mg/kg) by intravenous infusion and then randomized each animal to receive either hemoadsorption or a sham circuit for 4 hrs. Hemoadsorption was performed for 4 hrs using an arterial-venous circuit and a CytoSorb cartridge containing 10 g of polystyrene divinyl benzene copolymer beads with a biocompatible polyvinylpyrrolidone coating. Survival time was measured to a maximum of 12 hrs. In a separate set of experiments, we studied 12 animals using the same protocol except that we killed all animals at 4 hrs and removed standardized sections of liver for analysis of nuclear factor-kappaB DNA binding.

MEASUREMENTS AND MAIN RESULTS

Mean survival time among hemoadsorption-treated animals was 629+/-114 vs. 518+/-120 mins for sham-treated animals (p <.01). Overall survival (defined at 12 hrs) was also significantly better in the hemoadsorption group, seven of 20 vs. one of 20 (p <.05). Plasma interleukin-6 and interleukin-10 concentrations and liver nuclear factor-kappaB DNA binding were significantly reduced by hemoadsorption. Ex vivo experiments showed no endotoxin adsorption but strengthened our in vivo observations by showing rapid adsorption of tumor necrosis factor, interleukin-6, and interleukin-10.

CONCLUSIONS

Hemoadsorption was associated with reduced inflammation and improved survival in this murine model of septic shock.

Cytokine Removal with a Novel Adsorbent Polymer

BACKGROUND/AIMS

We sought to characterize a novel adsorbent polymer in terms of cytokine removal.

METHODS

We challenged 50 rats with lipopolysaccharide to obtain cytokine-rich blood and circulated this through cartridges containing polymer. In separate experiments, cell-free supernatants were passed through cartridges containing polymer. We measured tumor necrosis factor alpha, interleukin 10 and interleukin 6 concentrations under a variety of conditions to evaluate adsorption kinetics.

RESULTS

All three cytokines were rapidly removed from the blood with less than 50% of the initial concentrations present after 1 h of circulation through the cartridge. There was no significant difference in the effect across a range of blood flows and Ca2+ concentrations. Adsorption was decreased somewhat by extremely low temperature (4 degrees C).

CONCLUSION

The adsorbent polymer removes cytokines with high efficiency, and binding is relatively unaffected by a variety of physical conditions.

Interpreting the mechanisms of continuous renal replacement therapy in sepsis: the peak concentration hypothesis

Severe sepsis and septic shock are the primary causes of multiple organ dysfunction syndrome (MODS), which is the most frequent cause of death in intensive care unit patients. Many water-soluble mediators with pro- and anti-inflammatory action such as TNF, IL-6, IL-8, and IL-10 play a strategic role in septic syndrome. In intensive care medicine, blocking any one mediator has not led to a measurable outcome improvement in patients with sepsis. CRRT is a continuously acting therapy, which removes in a nonselective way pro- and anti-inflammatory mediators; "the peak concentration hypothesis" is the concept of cutting peaks of soluble mediators through continuous hemofiltration. Furthermore, there is evidence of increased efficacy of high-volume hemofiltration compared to conventional CVVH, and other blood purification techniques that utilize large-pore membranes or sorbent plasmafiltration are conceptually interesting.

Acute renal failure and multiple organ dysfunction in the ICU: from renal replacement therapy (RRT) to multiple organ support therapy (MOST)

Renal replacement therapy (RRT) has evolved from the concept that we need to treat the dysfunction of a single organ (the kidney). As intensive care units have become more and more complex, it has become clear that the majority of patients with acute renal failure often have dysfunction of several other organs. In order to facilitate single organ support in this setting, continuous renal replacement therapy (CRRT) techniques have been developed. However, CRRT has opened the door to the concept that targeting renal support as the only goal of extracorporeal blood purification may be a simplistic view of our therapeutic aims. In this article we argue that it is now time to move from the simple goal of achieving adequate renal support. The proper goal of extracorporeal blood purification in ICU should be multi-organ support therapy (MOST). We explain why MOST represents the most logical future conceptual and practical evolution of CRRT and illustrates the biological rationale, supplying animal and clinical evidence that confirms the need to move rapidly in this direction theoretically, practically and technologically.

The use of extracorporeal techniques to remove humoral factors in sepsis

OBJECTIVE

To determine whether there is sufficient evidence of a benefit of hemofiltration or plasma filtration in sepsis.

DATA SOURCES

Medline search, search of references in articles found in Medline search, literature known to local experts.

STUDY SELECTION

Trials and reports where clinical outcome measures were included.

DATA EXTRACTION

Clinically relevant information was presented.

DATA SYNTHESIS

Studies were grouped according to hemofiltration or plasma filtration and within each of these groups into animal or human studies; then they were graded from case report, through case series, nonrandomized trials, and randomized trials.

CONCLUSION

There is a lack of randomized trials. The available studies show an absence of benefit for hemofiltration. Further studies are needed in plasma filtration.

Clinical review: extracorporeal blood purification in severe sepsis

Sepsis and septic shock are the leading causes of acute renal failure, multiple organ system dysfunction, and death in the intensive care unit. The pathogenesis of sepsis is complex and comprises a mosaic of interconnected pathways. Several attempts to improve patient outcomes by targeting specific components of this network have been unsuccessful. For these reasons, the ideal immunomodulating strategy would be one that restores immunologic stability rather than blindly inhibiting or stimulating one or another component of this complex network. Hence, the recent focus of immunomodulatory therapy in sepsis has shifted to nonspecific methods of influencing the entire inflammatory response without suppressing it. Here, we discuss the various modalities of extracorporeal blood purification, the existing evidence, and future prospects.

Clinical trials of immunomodulatory therapies in severe sepsis and septic shock

Sepsis remains one of the leading causes of mortality in critically ill patients. Increased insight into the complexities of this disease process has resulted in the targeting of various aspects of the inflammatory response as offering potential therapeutic benefits. There have been encouraging results in the past few years. Some of the tested agents have been shown to improve mortality rates in large randomized controlled trials involving patients with severe sepsis. In this article, we discuss the positive and negative results of trials in this field; some of the possible reasons for the negative results are examined, and directions for the future are suggested.

Effect of hemofiltration filter adsorption on circulating IL-6 levels in septic rats

INTRODUCTION

Hemofiltration may modulate the inflammatory response in sepsis through a variety of mechanisms. We sought to distinguish clearance from adsorption as the principal mechanism responsible for reducing circulating IL-6 levels with hemofiltration.

MATERIALS AND METHODS

Nine hours after cecal ligation and puncture in 18 adult male Sprague-Dawley rats, we divided the rats into three groups (6 animals each) and placed groups 2 and 3 on a hemofiltration circuit connected between the right carotid artery and femoral vein using an AN69 membrane. In the hemofiltration group (group 2), ultrafiltrate was replaced with lactated Ringer's solution; in the recirculation group (group 3), the ultrafiltrate was reinfused into the animal. A sham group (group 1) had an arteriovenous circuit inserted but no hemofiltration. Blood was obtained for measurement of IL-6 and tumor necrosis factor (TNF) at the start of hemofiltration and after 5 and 11 hours of treatment.

RESULTS AND DISCUSSION

IL-6 levels increased only in the sham-treated animals (20.4 +/- 11.3 at baseline to 62.3 +/- 16.8 pg/ml at 11 hours, P = 0.03) (differences between groups 1 and 2, P = 0.015, and groups 1 and 3, P = 0.028). TNF levels were highly variable but not significantly different among the three groups.

CONCLUSION

Hemofiltration-associated reductions in circulating IL-6 levels appear to be secondary to adsorption of mediators to the filter membrane. We do not know whether this is due to direct adsorption of IL-6 per se or to the absorption of other mediators with secondary downregulation of IL-6 production or release. In addition, we could not exclude an interaction between adsorption and hemofiltration.

Hemofiltration, adsorption, sieving and the challenge of sepsis therapy design

Circulating inflammatory mediators spilling into the circulation from sites of active inflammation are considered the source of remote tissue injury and associated organ dysfunction in sepsis. Hemofiltration has been proposed as a therapy for sepsis based on its ability to remove circulating inflammatory mediators by sieving or by adsorption, or both. Designing devices and methods for sepsis therapy will require optimization of these two mechanisms. In the present issue of Critical Care Forum, Kellum and Dishart report the relative effects of sieving and adsorption on plasma IL-6 following cecal ligation and puncture in rats. The authors conclude that hemoadsorption is the main mechanism of removal, and discuss some possible implications for filter design but hemoadsorption is well dependant on hemofiltration (the so-called hemofiltration filter adsorption/synergistic effect). It is important to recognize the limitations of conventional systems; Kellum and Dishart have extended our knowledge of hemofiltration filter adsorption, which is quite different from conventional hemoadsorption. If sepsis is a manifestation of a nonlinear dynamic control system out of control, then filtration at modest doses with a large pore filter may succeed as well as high-volume hemofiltration with a conventional cut-off filter. In the present paper, we will explore the strengths and the weaknesses of the 'Kellum and Dishart' study and discussing their findings in the light of the current available literature.

Attenuation of sepsis-related immunoparalysis by continuous veno-venous hemofiltration in experimental porcine pancreatitis

OBJECTIVES

In light of evidence suggesting that hemofiltration favorably influences septic diseases by removing sepsis mediators, the impact of different modalities of continuous veno-venous hemofiltration (CVVH) on outcome and immunologic derangements in porcine pancreatogenic sepsis was evaluated.

DESIGN

Randomized, controlled intervention trial.

SUBJECTS

Forty-eight minipigs of either sex.

INTERVENTIONS

Pancreatitis was induced by intraductal injection of sodium taurocholate (4%, 1 mL/kg body weight [BW]) and enterokinase (2 U/kg BW). Animals were allocated either to untreated controls-group 1-or to one of three treatment groups-group 2: low-volume CVVH (20 mL/kg BW), no change of hemofilters; group 3: low-volume CVVH, filters changed every 12 hrs; and group 4: high-volume CVVH (100 mL/kg BW), filters changed every 12 hrs. Survival represented the major parameter of the study. Serum cytokine levels, sepsis-related down-regulation of major histocompatibility complex II and CD14 expression on leukocytes, bacterial translocation, and endotoxemia were further parameters evaluated in the study.

MEASUREMENTS AND MAIN RESULTS

High-volume CVVH combined with periodic filter change was significantly superior compared with less intensive treatment modalities (low-volume CVVH, no filter change) in sepsis protection. Long-term survival (>60 hrs) was found in 67% of group 4 and 33% of group 3 animals (p <.05), whereas in controls and group 2 no animal survived. CVVH ameliorated the initial serum tumor necrosis factor-alpha response and prevented sepsis-induced in vitro endotoxin hyporesponsiveness. Down-regulation of major histocompatibility complex II and CD14 expression on monocytes was significantly improved by CVVH. Improved oxidative burst and phagocytosis capacity in polymorphonuclear leukocytes suggested that leukocyte function was stabilized by CVVH. Also, CVVH significantly reduced bacterial translocation and endotoxemia.

CONCLUSIONS

Hemofiltration reversed sepsis-induced immunoparalysis in a porcine model of bile acid-induced pancreatitis. Implications for human pancreatitis must be validated in prospective, clinical protocols.

Septic shock

Infection is problematic because it affects many patients (adults and children), is a major cause of death in intensive care units (ICU) worldwide, and uses a large amount of hospital resources. The mortality rate among patients with septic shock varies but approximates 40% in infected patients admitted to ICUs. Because of the large number of adults dying of sepsis, many resources are expended. Children are physiologically different from adults, but nonetheless, many similarities exist with respect to the response to septic shock.

[Acute renal failure profile and prognostic value in severe acute pancreatitis]

BACKGROUND

Acute renal failure (ARF) complicating severe acute pancreatitis (SAP) carries a high mortality. Clinically useful scores to define patients who will develop this complication are lacking. We try to determine the incidence of ARF and variables predicting the appearance and severity of the episodes.

MATERIAL AND METHOD

Retrospective study of all SAP patients admitted in an intensive care unit between 1991 and 1998 (n = 154).

RESULTS

ARF incidence was 42%. Haemodynamic instability, APACHE II and Ranson score were related to ARF development. 62.2% of severe ARF patients had multiple organ failure (MOF). Mortality was 71.2% compared to 6.8% in patients without ARF (39.9% in mild ARF and 94.6% in severe ARF). Etiology relates to mortality (prerenal [46.4%], after severe hypotensive episode [71.4%], in MOF [93.3%]; p < 0.005). 63.6% patients required replacement therapy (hemofiltration [HF] 95.5%), with a mortality of 89.3% (100% for intermittent dialysis compared to 88% with HF). In 32% patients treated with HF, ARF improved (when initiated early mortality was 76.9% compared to a 100% when initiated in more advanced stages) (p < 0.001). Logistic regression analysis showed that ARF severity and haemodynamic failure were related with mortality.

CONCLUSION

ARF is a frequent and early complication of SAP, worsening its prognosis. FRA severity is related to the outcome. Need of replacement therapy supposes a high mortality. In this setting, HF seems to have advantages over conventional dialysis.