Hemofiltration with the Cascade system in an experimental porcine model of septic shock

Blood purification for sepsis: an overview

Sepsis is a life-threatening organ failure exacerbated by a maladaptive infection response from the host, and is one of the major causes of mortality in the intensive care unit. In recent decades, several extracorporeal blood purification techniques have been developed to manage sepsis by acting on both the infectious agents themselves and the host immune response. This research aims to summarize recent progress on extracorporeal blood purification technologies applied for sepsis, discuss unanswered questions on renal replacement therapy for septic patients, and present a decision-making strategy for practitioners.

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.

New modes of continuous renal replacement therapy using a refiltering technique to reduce micronutrient loss

INTRODUCTION

Micronutrient depletion is a major drawback of high-dose continuous renal replacement therapy (CRRT). We tested two novel CRRT modes, double-filtration hemofiltration (DHF) and dialysate-recycling hemodiafiltration (DHDF), aimed at reducing micronutrient loss while maintaining a high clearance rate of midsized solutes comparable to that of high-volume hemofiltration (HVHF).

METHODS

Forty patients with renal failure requiring CRRT were randomly assigned to receive predilutional standard-volume hemofiltration (SVHF, effluent rate 35 mL/kg/h), predilutional HVHF (100 mL/kg/h), DHF (35 mL/kg/h), and DHDF (30 mL/kg/h). In the two novel modes of CRRT, part of the high-volume primary effluent fluid produced by a high-flux filter (AV600S) was refiltered by two low-flux filters (15 L) for recycling as replacement fluid in DHF and dialysate in DHDF, while the remainder was discarded as final effluent fluid. Specimens were collected for measurement of trace elements, folic acid, amino acids (AAs), β2-microglobulin, cystatin C, and creatinine and for calculation of solute clearance.

FINDINGS

The clearance of 17 AAs, phosphorus, folic acid, copper, and zinc by DHF and DHDF was much lower than that by HVHF and comparable to that by SVHF. The estimated amount of AA loss by SVHF, HVHF, DHF, and DHDF was 10.3 (7.2-13.4) g/d, 22.1 (17.8-24.0) g/d, 10.6 (8.6-14.0) g/d, and 10.0 (8.6-11.4) g/d, respectively. Clearance of cystatin C and β2-microglobulin by DHF and DHDF was much greater than that by SVHF and equal to that by HVHF.

DISCUSSION

Compared to HVHF, DHF, and DHDF have an equal capacity for removal of large solutes but show substantially reduced micronutrient loss.

Efficacy of hemofiltration with PEPA membrane for IL-6 removal in a rat sepsis model

Recently, intensive care physicians have focused on continuous hemodiafiltration with a cytokine-adsorbing hemofilter in the treatment of sepsis. We aimed to establish extracorporeal circulation in a rat sepsis model to evaluate the cytokine removal properties of mini-modules using two types of membrane materials. Rats were divided into polyester polymer alloy (PEPA) and cellulose triacetate (CTA) groups as membrane materials of mini-modules. One hour after 0.1 mg/kg of lipopolysaccharide administration, continuous hemofiltration (CHF) was started in each group. Plasma interleukin-6 (IL-6), an important mediator of sepsis, was measured over time during hemofiltration. The peak IL-6 concentration in PEPA group was approximately 13,000 pg/mL, in comparison to approximately 31,000 pg/mL in CTA group. IL-6 clearance in PEPA group was much more than CTA group. Since IL-6 was not detected in the filtrate in PEPA group, it was considered that IL-6 was adsorbed to the membrane. In conclusion, our results suggest that CHF with PEPA hemofilter can be suitable for removing IL-6 from the blood stream efficiently.

Emergent Triglyceride-lowering Therapy With Early High-volume Hemofiltration Against Low-Molecular-Weight Heparin Combined With Insulin in Hypertriglyceridemic Pancreatitis: A Prospective Randomized Controlled Trial

OBJECTIVES

To compare the value of emergent triglyceride (TG)-lowering therapies between early high-volume hemofiltration (HVHF) and low-molecular-weight heparin (LMWH) combined with insulin (LMWH+insulin) as well as their effects on the outcomes of hypertriglyceridemic pancreatitis (HTGP) patients.

METHODS

In this randomized controlled trial, 66 HTGP patients presenting within 3 days after the onset of symptoms from August 2011 to October 2013 were assigned randomly to receive either HVHF or LMWH+insulin as an emergent TG-lowering therapy. Thirty-three patients were included in each group, and the therapy was started as soon as possible after admission. TG levels, clinical outcomes, and inflammatory biomarkers were compared between the 2 groups.

RESULTS

Thirty-two individuals in the HVHF group and 34 in the LMWH+insulin group were included in the final analysis. Characteristics of the patients in both groups were roughly comparable. HVHF could remove TG from the plasma and achieve its target (<500 mg/dL) in approximately 9 hours, whereas the target was not achieved within 48 hours in patients receiving the LMWH+insulin treatment (P<0.05). However, no differences were found in terms of the majority of the clinical outcomes, including local pancreatic complications (P>0.05), the requirement of surgical intervention (P=0.49), mortality (P=0.49), and the duration of hospitalization (P=0.144). Furthermore, an unexpectedly higher incidence of persistent organ failure was observed in the HVHF group compared with the LMWH+insulin group (risk ratio with HVHF, 2.42; 95% confidence interval, 1.15-5.11; P=0.01). Hospital charges for patients in the HVHF group were approximately 2-fold higher than those for patients in the LMWH+insulin group (5.20±4.90 vs. 2.92±3.21, P=0.03). We selected a systemic inflammatory response syndrome score of at least 2 at baseline as a predictor of SAP patients, and the subgroup analyses showed that HVHF cannot improve the prognosis of the predicted SAP patients compared with the LMWH+insulin group.

CONCLUSIONS

HVHF can lower TG levels more efficiently than LMWH+insulin therapy, but it is not superior in terms of clinical outcomes and costs. Further multicenter studies with large samples are required to clarify the feasibility of administering the HVHF treatment to HTGP patients (ChiCTR-TRC-13003274).

Very high volume hemofiltration with the Cascade system in septic shock patients

PURPOSE

We compared hemodynamic and biological effects of the Cascade system, which uses very high volume hemofiltration (HVHF) (120 mL kg(-1) h(-1)), with those of usual care in patients with septic shock.

METHODS

Multicenter, prospective, randomized, open-label trial in three intensive care units (ICU). Adults with septic shock with administration of epinephrine/norepinephrine were eligible. Patients were randomized to usual care plus HVHF (Cascade group), or usual care alone (control group). Primary end point was the number of catecholamine-free days up to 28 days after randomization. Secondary end points were number of days free of mechanical ventilation, renal replacement therapy (RRT) or ICU up to 90 days, and 7-, 28-, and 90-day mortality.

RESULTS

We included 60 patients (29 Cascade, 31 usual care). Baseline characteristics were comparable. Median number of catecholamine-free days was 22 [IQR 11-23] vs 20 [0-25] for Cascade vs control; there was no significant difference even after adjustment. There was no significant difference in number of mechanical ventilation-free days or ICU requirement. Median number of RRT-free days was 85 [46-90] vs 74 [0-90] for Cascade vs control groups, p = 0.42. By multivariate analysis, the number of RRT-free days was significantly higher in the Cascade group (up to 25 days higher after adjustment). There was no difference in mortality at 7, 28, or 90 days.

CONCLUSION

Very HVHF using the Cascade system can safely be used in patients presenting with septic shock, but it was not associated with a reduction in the need for catecholamines during the first 28 days.

Immunomodulatory therapy for sepsis: an update

Currently the treatment mainstay of sepsis is early and appropriate antibiotic therapy, accompanied by aggressive fluid administration, the use of vasopressors when needed and the prompt initiation of measures to support each failing organ. Activated protein C and hydrocortisone, when used accordingly can affect mortality. As the pathophysiologic events that take place during sepsis are being elucidated, new molecules that target each step of those pathways are being tested. However, a lot of those molecules affect various mediators of the sepsis cascade including inflammatory cytokines, cellular receptors, nuclear transcription factors, coagulation activators and apoptosis regulators. Over the last decade, a multitude of clinical trials and animal studies have investigated strategies that aimed to restore immune homeostasis either by reducing inflammation or by stimulating the innate and adaptive immune responses. Antibiotics, statins and other molecules with multipotent immunomodulatory actions have also been studied in the treatment of sepsis.

New insights regarding rationale, therapeutic target and dose of hemofiltration and hybrid therapies in septic acute kidney injury

Mediator removal from tissue (capillary blood compartment, CABC) and transport to the central circulation (central blood compartment, CEBC) must be effective. Effectiveness through a passive mechanism seems unlikely as the surface of CEBC (30 m(2)) is smaller than CABC (300 m(2)) whereby the former will be a limiting factor in passive transport. According to studies, a high exchange volume can induce an 80-fold increase in lymphatic flow. This results in displacement (active transport) of mediators to CEBC. Recent studies have shown that the delivered dose constitutes the mainstay of continuous renal replacement therapy. However, these results are not likely to change the recommendation: 35 ml/kg/h, adjusted for predilution, in septic acute kidney injury (AKI). Recently, studies were focusing on global intensive care unit AKI. In non-septic AKI, those studies show that 20-25 ml/kg/h was optimal. The DO-RE-MI trial underscored the importance of delivery which could be obtained by targeting doses between 5 and 10 ml/kg/h higher than prescribed. Until the IVOIRE trial becomes available, septic AKI should be treated by continuous veno-venous hemofiltration at 35 ml/kg/h. In non-septic AKI, 25 ml/kg/h remains optimal.

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.