Effect of hemofiltration on hemodynamics and systemic concentrations of anaphylatoxins and cytokines in human sepsis

Macrophage activation syndrome in Sepsis: from pathogenesis to clinical management

BACKGROUND

Sepsis represents a significant global health and hygiene challenge. Excessive activation of macrophages in sepsis can result in certain patients displaying characteristics akin to those observed in Macrophage Activation Syndrome (MAS). MAS represents a grave immune system disorder characterized by persistent and severe inflammation within the body. In the context of sepsis, MAS presents atypically, leading some researchers to refer to it as Macrophage Activation-Like Syndrome (MALS). However, there are currently no effective treatment measures for this situation. The purpose of this article is to explore potential treatment methods for sepsis-associated MALS.

OBJECTIVE

The objective of this review is to synthesize the specific pathophysiological mechanisms and treatment strategies of MAS to investigate potential therapeutic approaches for sepsis-associated MALS.

METHOD

We searched major databases (including PubMed, Web of Science, and Google Scholar etc.) for literature encompassing macrophage activation syndrome and sepsis up to Mar 2024 and combined with studies found in the reference lists of the included studies.

CONCLUSION

We have synthesized the underlying pathophysiological mechanism of MALS in sepsis, and then summarized the diagnostic criteria and the effects of various treatment modalities utilized in patients with MAS or MALS. In both scenarios, heterogeneous treatment responses resulting from identical treatment approaches were observed. The determination of whether the patient is genuinely experiencing MALS significantly impacts the ultimate outcomes of therapeutic efficacy. In order to tackle this concern, additional clinical trials and research endeavors are imperative.

Predicting mortality in acute kidney injury patients undergoing continuous renal replacement therapy using a visualization model: A retrospective study

Background: Patients with severe acute kidney injury (AKI) require continuous renal replacement therapy (CRRT) when hemodynamically unstable. We aimed to identify prognostic factors and develop a nomogram that could predict mortality in patients with AKI undergoing CRRT. Methods: Data were extracted from the Dryad Digital Repository. We enrolled 1,002 participants and grouped them randomly into training (n = 670) and verification (n = 332) datasets based on a 2:1 proportion. Based on Cox proportional modeling of the training set, we created a web-based dynamic nomogram to estimate all-cause mortality. Results: The model incorporated phosphate, Charlson comorbidity index, body mass index, mean arterial pressure, levels of creatinine and albumin, and sequential organ failure assessment scores as independent predictive indicators. Model calibration and discrimination were satisfactory. In the training dataset, the area under the curves (AUCs) for estimating the 28-, 56-, and 84-day all-cause mortality were 0.779, 0.780, and 0.787, respectively. The model exhibited excellent calibration and discrimination in the validation dataset, with AUC values of 0.791, 0.778, and 0.806 for estimating 28-, 56-, and 84-day all-cause mortality, respectively. The calibration curves exhibited the consistency of the model between the two cohorts. To visualize the results, we created a web-based calculator. Conclusion: We created a web-based calculator for assessing fatality risk in patients with AKI receiving CRRT, which may help rationalize clinical decision-making and personalized therapy.

Evaluation of the timing of initiating continuous renal replacement therapy in community-acquired septic patients with acute kidney injury

Acute kidney injury (AKI) in community-acquired septic patients is often associated with relatively high mortality rate. However, the appropriate timing for continuous renal replacement therapy (CRRT) initiation remains controversial. In the present study, we retrospectively analyzed 123 community-acquired septic patients with AKI admitted to the medical intensive care unit (ICU). The baseline patient characteristics and renal function parameters were compared between survivors and non-survivors. Then, we used the Cox proportional hazard analysis to identify the risk factors for ICU mortality. Moreover, we employed the area under the receiver operating characteristic curve analysis to determine the cutoff time for CRRT initiation. Finally, we used the cutoff time to separate the patients into early (treatment initiated earlier than the cutoff time) and late (treatment initiated later than the cutoff time) CRRT groups and performed the Kaplan-Meier survival analysis to assess the overall mortalities. At the time of ICU release, the mortality rate of the 123 patients was 48.8% (n = 60). We identified several baseline characteristics and renal function parameters that were significantly different between the survivors and the non-survivors. All of them were also identified as the risk factors for community-acquired sepsis. Importantly, the cutoff time point to distinguish the early and late CRRT initiation groups was determined to be 16 h after AKI onset. Based on such grouping, the mortality rate was significantly lower in the early CRRT initiation group at 30, 60 and 90 days. Our data suggest that initiating CRRT within 16 h may help improve the mortality rate of community-acquired septic patients.

Timing of Renal Replacement Therapy for Severe Acute Kidney Injury in Critically Ill Patients

Acute kidney injury (AKI) affects many ICU patients and is responsible for increased morbidity and mortality. Although lifesaving in many situations, renal replacement therapy (RRT) may be associated with complications, and the appropriate timing of its initiation is still the subject of intense debate. An early initiation strategy can prevent some metabolic complications, whereas a delayed one may allow for renal function recovery in some patients without need for this costly and potentially dangerous technique. For years, most of the knowledge on this issue stemmed from observational studies or small randomized controlled trials. Recent randomized controlled trials have indicated that a watchful waiting strategy (in the absence of life-threatening conditions such as severe hyperkalemia or pulmonary edema) during severe AKI allowed many patients to escape RRT and did not seem to adversely affect survival compared with a strategy of immediate RRT. In addition, data suggest that a delayed strategy may reduce the rate of complications (such as catheter infection) and favor renal function recovery. Ongoing studies will have to both confirm these conclusions and clarify to what extent the delay in initiating RRT can be prolonged. Pending those results, the bulk of evidence suggests that, in the absence of potential severe complications of AKI, delaying RRT is a valid and safe strategy that may also allow for considerable cost savings.

Timing of Renal Support and Outcome of Septic Shock and Acute Respiratory Distress Syndrome. A Post Hoc Analysis of the AKIKI Randomized Clinical Trial

RATIONALE

The optimal strategy for initiation of renal replacement therapy (RRT) in patients with severe acute kidney injury in the context of septic shock and acute respiratory distress syndrome (ARDS) is unknown.

OBJECTIVES

To examine the effect of an early compared with a delayed RRT initiation strategy on 60-day mortality according to baseline sepsis status, ARDS status, and severity.

METHODS

Post hoc analysis of the AKIKI (Artificial Kidney Initiation in Kidney Injury) trial.

MEASUREMENTS AND MAIN RESULTS

Subgroups were defined according to baseline characteristics: sepsis status (Sepsis-3 definition), ARDS status (Berlin definition), Simplified Acute Physiology Score 3 (SAPS 3), and Sepsis-related Organ Failure Assessment (SOFA). Of 619 patients, 348 (56%) had septic shock and 207 (33%) had ARDS. We found no significant influence of the baseline sepsis status (P = 0.28), baseline ARDS status (P = 0.94), and baseline severity scores (P = 0.77 and P = 0.46 for SAPS 3 and SOFA, respectively) on the comparison of 60-day mortality according to RRT initiation strategy. A delayed RRT initiation strategy allowed 45% of patients with septic shock and 46% of patients with ARDS to escape RRT. Urine output was higher in the delayed group. Renal function recovery occurred earlier with the delayed RRT strategy in patients with septic shock or ARDS (P < 0.001 and P = 0.003, respectively). Time to successful extubation in patients with ARDS was not affected by RRT strategy (P = 0.43).

CONCLUSIONS

Early RRT initiation strategy was not associated with any improvement of 60-day mortality in patients with severe acute kidney injury and septic shock or ARDS. Unnecessary and potentially risky procedures might often be avoided in these fragile populations. Clinical trial registered with www.clinicaltrials.gov (NCT 01932190).

Cytokine Removal during Continuous Renal Replacement Therapy: An Ex Vivo Comparison of Convection and Diffusion

Background and objectives

It is unknown whether cytokine adsorption to the membrane during continuous renal replacement therapy is affected by the technique. Such knowledge might affect the choice of technique in vivo. Accordingly, we conducted an ex vivo study to test whether continuous veno-venous hemofiltration (CVVH) or continuous veno-venous hemodialysis (CVVHD) affect cytokine adsorption differently.

Setting

Laboratory attached to the Intensive Care Unit of a tertiary hospital

Design

Six healthy human volunteers donated blood, which was incubated with endotoxin. Control blood was left at room temperature, and treatment blood was recirculated for eight hours through closed circuits using polyacrylonitrile membranes (AN69). The effect of CVVH and CVVHD on cytokine removal from the circuits was compared.

Measurements

The concentrations of interleukins (IL)-1ß, 6, 8, 10 and TNF were measured in the control samples, pre-and post-filter and in the effluent at baseline and hourly thereafter. The clearances by adsorption, and filtration were calculated.

Results

Control cytokine concentrations remained the same or increased slightly. Adsorption was the major mechanism of removal for all cytokines with the exception of IL-1ß, but the effect was short-lived. Peak adsorption generally occurred at baseline before the start of CVVH and CVVHD, with clearances ranging from 43.7ml/min (for IL-8) to 7.6ml/min (for IL-10). The time-weighted average total clearances during CVVH were 23.3, 4.3, 3.8, –2.0, and 15ml/min for IL-8, IL-1ß, TNF, IL-6, and IL-10 respectively. The corresponding clearances during CVVHD were 19.0, 10.7, 2.7, 2.4, and 0.3ml/min. IL-10 clearances were greater during CVVH than CVVHD (p=0.03). Non adsorptive CVVH clearance of IL-1ß was greater than CVVHD clearance, but this advantage was outweighed by an increased tendency of the membrane to release IL-1ß into the circuit during HF.

Conclusions

The technique of solute removal had only a minor effect on the magnitude of cytokine adsorption, and neither technique had the advantage for all the measured cytokines.

High-dose versus low-dose haemofiltration for the treatment of critically ill patients with acute kidney injury: an updated systematic review and meta-analysis

OBJECTIVE

The purpose of this study was to perform a systematic review and meta-analysis to evaluate the effect of high-dose versus low-dose haemofiltration on the survival of critically ill patients with acute kidney injury (AKI). We hypothesised that high-dose treatments are not associated with a higher risk of mortality.

DESIGN

Meta-analysis.

SETTING

Randomised controlled trials and two-arm prospective and retrospective studies were included.

PARTICIPANTS

Critically ill patients with AKI.

INTERVENTIONS

Continuous renal replacement therapy.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcomes: 90-day mortality, intensive care unit (ICU) mortality, hospital mortality; secondary outcomes: length of ICU and hospital stay.

RESULT

Eight studies including 2970 patients were included in the analysis. Pooled results showed no significant difference in the 90-mortality rate between patients treated with high-dose or low-dose haemofiltration (pooled OR=0.90, 95% CI 0.73 to 1.11, p=0.32). Findings were similar for ICU (pooled OR=1.12, 95% CI 0.94 to 1.34, p=0.21) and hospital mortality (pooled OR=1.03, 95% CI 0.81 to 1.30, p=0.84). Length of ICU and hospital stay were similar between high-dose and low-dose groups. Pooled results are not overly influenced by any one study, different cut-off points of prescribed dose or different cut-off points of delivered dose. Meta-regression analysis indicated that the results were not affected by the percentage of patients with sepsis or septic shock.

CONCLUSION

High-dose and low-dose haemofiltration produce similar outcomes with respect to mortality and length of ICU and hospital stay in critically ill patients with AKI.This study was not registered at the time the data were collected and analysed. It has since been registered on 17 February 2017 at http://www.researchregistry.com/, registration number: reviewregistry211.

High-volume haemofiltration for sepsis in adults

BACKGROUND

Severe sepsis and septic shock are leading causes of death in the intensive care unit (ICU), despite advances in the treatment of patients with severe sepsis and septic shock, including early recognition, appropriate treatment with antibiotics and support of organs that may have been affected by the illness. High-volume haemofiltration (HVHF) is a blood purification technique that may improve outcomes in severe sepsis or septic shock. The technique of HVHF has evolved from renal replacement therapies used in the ICU to treat critically ill patients with acute kidney injury (AKI). This review was first published in 2013 and was updated in 2016.

OBJECTIVES

To investigate whether HVHF improves outcomes in critically ill adults admitted to the intensive care unit with severe sepsis or septic shock. The primary outcome of this systematic review is patient mortality; secondary outcomes include duration of stay, severity of organ dysfunction and adverse events.

SEARCH METHODS

For this updated version, we extended searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Latin American Caribbean Health Sciences Literature (LILACS), Web of Science and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) to 31 December 2015. The original search was performed in 2011. We also searched trials registers.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-randomized trials comparing HVHF or high-volume haemodiafiltration versus standard or usual dialysis therapy, as well as RCTs and quasi-randomized trials comparing HVHF or high-volume haemodiafiltration versus no similar dialysis therapy. These studies involved adults treated in critical care units.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted data and assessed trial quality. We sought additional information from trialists as required.

MAIN RESULTS

We included four randomized trials involving 200 participants. Owing to small numbers of studies and participants, it was not possible to combine data for all outcomes. Two trials reported 28-day mortality, and one trial reported hospital mortality; in the third trial, the number of deaths stated did not match the quoted mortality rates. The pooled risk ratio (95% confidence interval) for 28-day mortality associated with HVHF was 0.89 (0.60 to 1.32, two trials, 146 participants, low-quality evidence). One study (137 participants, low-quality evidence) reported length of stay in the ICU. Two trials (170 participants, low-quality evidence) reported organ dysfunction, but we could not pool results owing to reporting differences. Three studies (189 participants, low-quality evidence) reported on haemodynamic changes, but we could not pool results owing to reporting differences. Investigators reported no adverse events. Overall, the included studies had low risk of bias.

AUTHORS' CONCLUSIONS

Investigators reported no adverse effects of HVHF (low-quality evidence). The results of this meta-analysis show that very few studies have been conducted to investigate the use of HVHF in critically ill patients with severe sepsis or septic shock (four studies, 201 participants, low-quality evidence). Researchers should consider additional randomized controlled trials that are large and multi-centred and have clinically relevant outcome measures. The cost-effectiveness of HVHF should also be studied. .

Safety and Efficacy of Combined Extracorporeal CO2 Removal and Renal Replacement Therapy in Patients With Acute Respiratory Distress Syndrome and Acute Kidney Injury: The Pulmonary and Renal Support in Acute Respiratory Distress Syndrome Study

OBJECTIVE

To assess the safety and efficacy of combining extracorporeal CO2 removal with continuous renal replacement therapy in patients presenting with acute respiratory distress syndrome and acute kidney injury.

DESIGN

Prospective human observational study.

SETTINGS

Patients received volume-controlled mechanical ventilation according to the acute respiratory distress syndrome net protocol. Continuous venovenous hemofiltration therapy was titrated to maintain maximum blood flow and an effluent flow of 45 mL/kg/h with 33% predilution.

PATIENTS

Eleven patients presenting with both acute respiratory distress syndrome and acute kidney injury required renal replacement therapy.

INTERVENTIONS

A membrane oxygenator (0.65 m) was inserted within the hemofiltration circuit, either upstream (n = 7) or downstream (n = 5) of the hemofilter. Baseline corresponded to tidal volume 6 mL/kg of predicted body weight without extracorporeal CO2 removal. The primary endpoint was 20% reduction in PaCO2 at 20 minutes after extracorporeal CO2 removal initiation. Tidal volume was subsequently reduced to 4 mL/kg for the remaining 72 hours.

MEASUREMENTS AND MAIN RESULTS

Twelve combined therapies were conducted in the 11 patients. Age was 70 ± 9 years, Simplified Acute Physiology Score II was 69 ± 13, Sequential Organ Failure Assessment score was 14 ± 4, lung injury score was 3 ± 0.5, and PaO2/FIO2 was 135 ± 41. Adding extracorporeal CO2 removal at tidal volume 6 mL/kg decreased PaCO2 by 21% (95% CI, 17-25%), from 47 ± 11 to 37 ± 8 Torr (p < 0.001). Lowering tidal volume to 4 mL/kg reduced minute ventilation from 7.8 ± 1.5 to 5.2 ± 1.1 L/min and plateau pressure from 25 ± 4 to 21 ± 3 cm H2O and raised PaCO2 from 37 ± 8 to 48 ± 10 Torr (all p < 0.001). On an average of both positions, the oxygenator's blood flow was 410 ± 30 mL/min and the CO2 removal rate was 83 ± 20 mL/min. The oxygenator blood flow (p <0.001) and the CO2 removal rate (p = 0.083) were higher when the membrane oxygenator was placed upstream of the hemofilter. There was no safety concern.

CONCLUSIONS

Combining extracorporeal CO2 removal and continuous venovenous hemofiltration in patients with acute respiratory distress syndrome and acute kidney injury is safe and allows efficient blood purification together with enhanced lung protective ventilation.

A patient with AKI after cardiac surgery

Up to 30% of patients undergoing cardiac surgery develop AKI, with 1% requiring RRT. AKI is an independent risk factor for morbidity and mortality. Postoperatively, even minimal changes in serum creatinine are associated with a substantial increase in mortality. No intervention has been definitely proven effective in reducing kidney injury. The successful prevention and management of AKI involves identifying patients at risk for AKI, recognizing subtle abnormalities in a timely manner, performing basic clinical assessments, and responding appropriately to data obtained. With that in mind, in this Attending Rounds, a woman with AKI in the setting of cardiac surgery is presented to highlight the use of history, physical exam, hemodynamic monitoring, laboratory data trends, and urine indices in establishing the correct diagnosis and appropriate management.

High-volume versus standard-volume haemofiltration for septic shock patients with acute kidney injury (IVOIRE study): a multicentre randomized controlled trial

PURPOSE

Septic shock is a leading cause of death among critically ill patients, in particular when complicated by acute kidney injury (AKI). Small experimental and human clinical studies have suggested that high-volume haemofiltration (HVHF) may improve haemodynamic profile and mortality. We sought to determine the impact of HVHF on 28-day mortality in critically ill patients with septic shock and AKI.

METHODS

This was a prospective, randomized, open, multicentre clinical trial conducted at 18 intensive care units in France, Belgium and the Netherlands. A total of 140 critically ill patients with septic shock and AKI for less than 24 h were enrolled from October 2005 through March 2010. Patients were randomized to either HVHF at 70 mL/kg/h or standard-volume haemofiltration (SVHF) at 35 mL/kg/h, for a 96-h period.

RESULTS

Primary endpoint was 28-day mortality. The trial was stopped prematurely after enrolment of 140 patients because of slow patient accrual and resources no longer being available. A total of 137 patients were analysed (two withdrew consent, one was excluded); 66 patients in the HVHF group and 71 in the SVHF group. Mortality at 28 days was lower than expected but not different between groups (HVHF 37.9 % vs. SVHF 40.8 %, log-rank test p = 0.94). There were no statistically significant differences in any of the secondary endpoints between treatment groups.

CONCLUSIONS

In the IVOIRE trial, there was no evidence that HVHF at 70 mL/kg/h, when compared with contemporary SVHF at 35 mL/kg/h, leads to a reduction of 28-day mortality or contributes to early improvements in haemodynamic profile or organ function. HVHF, as applied in this trial, cannot be recommended for treatment of septic shock complicated by AKI.

Techniques of extracorporeal cytokine removal: a systematic review of human studies

BACKGROUND AND AIMS

Hypercytokinemia is believed to be harmful and reducing cytokine levels is considered beneficial. Extracorporeal blood purification (EBP) techniques have been studied for the purpose of cytokine reduction. We aimed to study the efficacy of various EBP techniques for cytokine removal as defined by technical measures.

METHOD

We conducted a systematic search for human clinical trials which focused on technical measures of cytokine removal by EBP techniques. We identified 41 articles and analyzed cytokine removal according to clearance (CL), sieving coefficient (SC), ultrafiltrate (UF) concentration and percentage removed.

RESULTS

We identified the following techniques for cytokine removal: standard hemofiltration, high volume hemofiltration (HVHF), high cut-off (HCO) hemofiltration, plasma filtration techniques, and adsorption techniques, ultrafiltration (UF) techniques relating to cardiopulmonary bypass (CPB), extracorporeal liver support systems and hybrid techniques including combined plasma filtration adsorption. Standard filtration techniques and UF techniques during CPB were generally poor at removing cytokines (median CL for interleukin 6 [IL-6]: 1.09 mL/min, TNF-alpha 0.74 mL/min). High cut-off techniques consistently offered moderate cytokine removal (median CL for IL-6: 26.5 mL/min, interleukin 1 receptor antagonist [IL-1RA]: 40.2 mL/min). Plasma filtration and extracorporeal liver support appear promising but data are few. Only one paper studied combined plasma filtration and adsorption and found low rates of removal. The clinical significance of the cytokine removal achieved with more efficacious techniques is unknown.

CONCLUSION

Human clinical trials indicate that high cut-off hemofiltration techniques, and perhaps plasma filtration and extracorporeal liver support techniques are likely more efficient in removing cytokines than standard techniques.

Plasmapheresis adjusts inflammatory responses in potential kidney transplant recipients

BACKGROUND

Plasmapheresis (PP) has been used in the treatment of various immunologic disorders, and its efficacy has mainly been attributed to the removal of humoral factors and autoantibodies. Besides these effects, PP may induce modifications of the cellular immunologic status, contributing to the restoration of impaired immunologic function. The effect of PP on lymphocyte subpopulations, plasma neopterin, and cytokines in renal transplant recipients was investigated in this study.

METHODS

We compared pre-PP and post-PP lymphocyte subpopulations and plasma neopterin in 37, and cytokine plasma levels in 30, potential renal transplant recipients. Plasma neopterin and cytokines were measured by enzyme-linked immunosorbent assay kits, lymphocyte subsets were determined using four-color fluorescence flow cytometry.

RESULTS

Lymphocyte subpopulation counts and ratios including CD45:μL (P=0.005), CD3:μL (P=0.02), CD4DR:μL (P=0.002), CD8:μL (P=0.01), and CD8DR:μL (P=0.005) T cells; CD4DR:CD4 (P=0.009) and CD8DR:CD8 (P=0.0004) ratios; DR cells:μL (P=0.003); CD19 B lymphocytes:μL (P=0.001); and plasma levels of neopterin (P<;0.0001), soluble interleukin-1 receptor antagonist (P<;0.0001), IL-8 (P=0.0001), and tumor necrosis factor-α (P=0.008) were significantly decreased after PP as compared with before PP. The results indicate a decrease of activated DR, CD4, and CD8 T lymphocytes and B lymphocytes, and a decrease of monocyte and macrophage activation as a result of PP.

CONCLUSION

Based on these results, we conclude that PP not only removes antibodies from the plasma but, in addition, modulates T-lymphocyte activation and the inflammatory response by decreasing plasma proinflammatory cytokines.

High-volume haemofiltration for sepsis

BACKGROUND

Severe sepsis and septic shock are leading causes of death in the intensive care unit (ICU). This is despite advances in the management of patients with severe sepsis and septic shock including early recognition, source control, timely and appropriate administration of antimicrobial agents, and goal directed haemodynamic, ventilatory and metabolic therapies. High-volume haemofiltration (HVHF) is a blood purification technique which may improve outcomes in critically ill patients with severe sepsis or septic shock. The technique of HVHF has evolved from renal replacement therapies used to treat acute kidney injury (AKI) in critically ill patients in the ICU.

OBJECTIVES

This review assessed whether HVHF improves clinical outcome in adult critically ill patients with sepsis in an ICU setting.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2011, Issue 7); MEDLINE (1990 to August 2011), EMBASE (1990 to August 2011); LILACS (1982 to August 2011), Web of Science (1990 to August 2011), CINAHL (1982 to August 2011) and specific websites.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-randomized trials comparing HVHF or high-volume haemodiafiltration to standard or usual dialysis therapy; and RCTs and quasi-randomized trials comparing HVHF or high-volume haemodiafiltration to no similar dialysis therapy. The studies involved adults in critical care units.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted data and assessed trial quality. We sought additional information as required from trialists.

MAIN RESULTS

We included three randomized trials involving 64 participants. Due to the small number of studies and participants, it was not possible to combine data or perform sub-group analyses. One trial reported ICU and 28-day mortality, one trial reported hospital mortality and in the third, the number of deaths stated did not match the quoted mortality rates. No trials reported length of stay in ICU or hospital and one reported organ dysfunction. No adverse events were reported. Overall, the included studies had a low risk of bias.

AUTHORS' CONCLUSIONS

There were no adverse effects of HVHF reported.There is insufficient evidence to recommend the use of HVHF in critically ill patients with severe sepsis and or septic shock except as interventions being investigated in the setting of a randomized clinical trial. These trials should be large, multi-centred and have clinically relevant outcome measures. Financial implications should also be assessed.

Role of apheresis and dialysis in pediatric living donor liver transplantation: a single center retrospective study

In the field of pediatric living donor liver transplantation, the indications for apheresis and dialysis, and its efficacy and safety are still a matter of debate. In this study, we performed a retrospective investigation of these aspects, and considered its roles. Between January 2008 and December 2010, 73 living donor liver transplantations were performed in our department. Twenty seven courses of apheresis and dialysis were performed for 19 of those patients (19/73; 26.0%). The indications were ABO incompatible-liver transplantation in 11 courses, fluid management in seven, acute liver failure in three, renal replacement therapy in two, endotoxin removal in two, cytokine removal in one, and liver allograft dysfunction in one. Sixteen courses of apheresis and dialysis were performed prior to liver transplantation for 14 patients. The median IgM antibody titers before and after apheresis for ABO blood type-incompatible liver transplantation was 128 and eight, respectively (P < 0.05). Eleven courses of apheresis and dialysis were performed post liver transplantation for 10 patients. The median PaO2/FiO2 ratio before and after dialysis for fluid overload was 159 and 339, respectively (P < 0.05). No bleeding or technical complications attributable to apheresis and dialysis occurred. The 1-year survival rate of the patients was 100%. Apheresis and dialysis in pediatric living donor liver transplantation are effective for antibody removal in ABO-incompatible liver transplantation, and fluid management for acute respiratory failure.

High versus standard-volume haemofiltration in hyperdynamic porcine peritonitis: effects beyond haemodynamics?

OBJECTIVE

The role of haemofiltration as an adjunctive treatment of sepsis remains a contentious issue. To address the role of dose and to explore the biological effects of haemofiltration we compared the effects of standard and high-volume haemofiltration (HVHF) in a peritonitis-induced model of porcine septic shock.

DESIGN AND SETTING

Randomized, controlled experimental study.

SUBJECTS

Twenty-one anesthetized and mechanically ventilated pigs.

INTERVENTIONS

After 12 h of hyperdynamic peritonitis, animals were randomized to receive either supportive treatment (Control, n = 7) or standard haemofiltration (HF 35 ml/kg per h, n = 7) or HVHF (100 ml/kg per hour, n = 7).

MEASUREMENTS AND RESULTS

Systemic and hepatosplanchnic haemodynamics, oxygen exchange, energy metabolism (lactate/pyruvate, ketone body ratios), ileal and renal cortex microcirculation and systemic inflammation (TNF-alpha, IL-6), nitrosative/oxidative stress (TBARS, nitrates, GSH/GSSG) and endothelial/coagulation dysfunction (von Willebrand factor, asymmetric dimethylarginine, platelet count) were assessed before, 12, 18, and 22 h of peritonitis. Although fewer haemofiltration-treated animals required noradrenaline support (86, 43 and 29% animals in the control, HF and HVHF groups, respectively), neither of haemofiltration doses reversed hyperdynamic circulation, lung dysfunction and ameliorated alterations in gut and kidney microvascular perfusion. Both HF and HVHF failed to attenuate sepsis-induced alterations in surrogate markers of cellular energetics, nitrosative/oxidative stress, endothelial injury or systemic inflammation.

CONCLUSIONS

In this porcine model of septic shock early HVHF proved superior in preventing the development of septic hypotension. However, neither of haemofiltration doses was capable of reversing the progressive disturbances in microvascular, metabolic, endothelial and lung function, at least within the timeframe of the study and severity of the model.

Renal replacement strategies in the ICU

Acute renal failure (ARF) with the concomitant need for renal replacement therapy (RRT) is a common complication of critical care medicine that is still associated with high mortality. Different RRT strategies, like intermittent hemodialysis, continuous venovenous hemofiltration, or hybrid forms that combine the advantages of both techniques, are available and will be discussed in this article. Since a general survival benefit has not been demonstrated for either method, it is the task of the nephrologist or intensivist to choose the RRT strategy that is most advantageous for each individual patient. The underlying disease, its severity and stage, the etiology of ARF, the clinical and hemodynamic status of the patient, the resources available, and the different costs of therapy may all influence the choice of the RRT strategy. ARF, with its risk of uremic complications, represents an independent risk factor for outcome in critically ill patients. In addition, the early initiation of RRT with adequate doses is associated with improved survival. Therefore, the "undertreatment" of ARF should be avoided, and higher RRT doses than those in patients with chronic renal insufficiency, independent of whether convective or diffusive methods are used, are indicated in critically ill patients. However, clear guidelines on the dose of RRT and the timing of initiation are still lacking. In particular, it remains unclear whether hemodynamically unstable patients with septic shock benefit from early RRT initiation and the use of increased RRT doses, and whether RRT can lead to a clinically relevant removal of inflammatory mediators.

Renal replacement therapy in the treatment of acute renal failure-intermittent and continuous

Renal replacement therapy (RRT) is increasingly used in intensive care as acute renal failure (ARF) is a common and constantly increasing complication in this setting. Different forms of RRT such as intermittent hemodialysis, continuous hemofiltration, or hybrid forms, which combine advantages of both, are available and will be discussed in this article. As a general survival benefit for neither method has been demonstrated, it is the task of the nephrologist or intensivist to choose the RRT strategy that is most advantageous for each individual patient. The choice of RRT might depend not only on the underlying disease, the time course of the disease, the etiology of ARF, the actual clinical status of the patient but also on the resources available and the cost of therapy. An adequate dose of RRT seems to result in improved survival in patients with ARF. However, clear guidelines on the dose of RRT and the timing of initiation are still lacking. Moreover, it will be discussed whether patients with sepsis and septic shock benefit from early RRT initiation, the use of increased RRT doses, and increased removal of inflammatory mediators by RRT.

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.

Continuous renal replacement therapy in patients following traumatic injury

In critically injured patients, the incidence of acute renal failure has been reported to occur in as many as 31% of patients. The use of CRRT modalities for patients following traumatic injuries is becoming more common, albeit slowly, and this therapy may impact upon long-term recovery of renal function and mortality. Historical studies investigating the early use of intermittent dialysis reported significant improvement in survival in patients who were dialyzed earlier and more vigorously than in control subjects. Early trauma patients also showed improved survival following war injuries when dialyzed prophylactically. Although there is a growing acceptance in favor of earlier renal replacement therapy, the published consensus and the practice in many centers has been to dialyze/filter relatively ill rather than relatively healthy patients. The R Adams Cowley Shock Trauma Center (STC) in Baltimore, Maryland, USA, admits over 8,000 trauma patients each year. Within the STC, a program of continuous renal replacement therapy was established in the early 1980's. We review both historical and current literature on the use of renal replacement therapies after traumatic injury, and suggest some future areas of investigation and indications for these modalities.

Therapeutic intervention and targets for sepsis

Sepsis syndrome, a systemic response to infection, can beget devastating outcomes even in previously normal individuals. Recent research in septic patients has led to the discovery that early goal-directed resuscitation guided by continuous monitoring of mixed venous hemoglobin saturation, along with moderate doses of corticosteroids, can reduce mortality. An improved understanding of the complex interaction between the inflammatory and coagulant systems in sepsis pathophysiology has resulted in novel treatments, such as recombinant human activated protein C, which improves survival in patients with severe sepsis and a high risk of death. However, despite an increased understanding of the complex pathophysiology of this syndrome and the discovery of new, effective treatments, severe sepsis still results in significant morbidity and mortality. Consequently, investigations continue into additional therapeutic agents directed against novel targets. Following a review of recent advances in sepsis treatment, we briefly discuss a few of the new, promising therapeutic strategies currently being investigated.

Amelioration of hemodynamics and oxygen metabolism by continuous venovenous hemofiltration in experimental porcine pancreatitis

AIM: To investigate the potential role of continuous venovenous hemofiltration (CVVH) in hemodynamics and oxygen metabolism in pigs with severe acute pancreatitis (SAP).

METHODS: SAP model was produced by intraductal injection of sodium taurocholate [4%, 1 mL/kg body weight (BW)] and trypsin (2 U/kg BW). Animals were allocated either to untreated controls as group 1 or to one of two treatment groups as group 2 receiving a low-volume CVVH [20 mL/(kg.h)], and group 3 receiving a high-volume CVVH [100 (mL/kg.h)]. Swan-Ganz catheter was inserted during the operation. Heart rate, arterial blood pressure, cardiac output, mean pulmonary arterial pressure, pulmonary arterial wedge pressure, central venous pressure, systemic vascular resistance, oxygen delivery, oxygen consumption, oxygen extraction ratio, as well as survival of pigs were evaluated in the study.

RESULTS: Survival time was significantly prolonged by low-volume and high-volume CVVHs, which was more pronounced in the latter. High-volume CVVH was significantly superior compared with less intensive treatment modalities (low-volume CVVH) in systemic inflammatory reaction protection. The major hemodynamic finding was that pancreatitis-induced hypotension was significantly attenuated by intensive CVVH (87.4±12.5 kPa vs 116.3±7.8 kPa, P<0.01). The development of hyperdynamic circulatory failure was simultaneously attenuated, as reflected by a limited increase in cardiac output, an attenuated decrease in systemic vascular resistance and an elevation in oxygen extraction ratio.

CONCLUSION: CVVH blunts the pancreatitis-induced cardiovascular response and increases tissue oxygen extraction. The high-volume CVVH is distinctly superior in preventing sepsis-related hemodynamic impairment.

Adjunctive therapies in sepsis: An evidence-based review

OBJECTIVE

In 2003, critical care and infectious disease experts representing 11 international organizations developed management guidelines for adjunctive therapies in sepsis that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and to improve outcome in severe sepsis.

DESIGN

The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee.

METHODS

The modified Delphi methodology used for grading recommendations built on a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along five levels to create recommendation grades from A to E, with A being the highest grade. Pediatric considerations to contrast adult and pediatric management are in the article by Parker et al. on p. S591.

CONCLUSION

Glycemic control (maintenance of glucose <150 mg/dL) is recommended. The beneficial effect of glycemic control appears to be related control of glucose and not the administration of insulin. Glycemic control should be combined with a nutritional protocol. The dialysis dose is important in sepsis-induced acute renal failure. Continuous hemofiltration offers easier management of fluid balance in hemodynamically unstable septic patients but in the absence of hemodynamic instability is equivalent to intermittent hemodialysis. It is uncertain whether high-volume hemofiltration improves prognosis in sepsis. Bicarbonate therapy is not recommended for the purpose of improving hemodynamics or reducing vasopressor requirements in the presence of lactic academia and pH >7.15.

Intermittent high permeability hemofiltration in septic patients with acute renal failure

OBJECTIVE

High permeability hemofiltration (HP-HF) is a new renal replacement modality designed to facilitate the elimination of cytokines in sepsis. Clinical safety data on this new procedure is still lacking. This study investigates the effects of HP-HF on the protein and coagulation status as well as on cardiovascular hemodynamics in patients with septic shock. In addition, the clearance capacity for interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) is analyzed.

DESIGN

Prospective, single-center pilot trial.

SETTING

University hospital.

PATIENTS

Sixteen patients with multiple organ failure (MOF) induced by septic shock were studied.

INTERVENTION

Patients were treated by intermittent high permeability hemofiltration (iHP-HF; nominal cut-off point: 60 kilodaltons). Intermittent HP-HF was performed over 5 days for 12 h per day and alternated with conventional hemofiltration.

MEASUREMENTS AND RESULTS

Intermittent HP-HF proved to be a safe hemofiltration modality in regard to cardiovascular hemodynamics and its impact on the coagulation status. However, transmembrane protein loss occurred and cumulative 12-h protein loss was 7.60 g (IQR: 6.2-12.0). The filtration capacity for IL-6 was exceptionally high. The IL-6 sieving coefficient approximated 1 throughout the study period. The total plasma IL-6 burden, estimated by area under curve analysis, declined over time ( p<0.001 vs baseline). The TNF-alpha elimination capacity was poor.

CONCLUSIONS

High permeability hemofiltration is a new approach in the adjuvant therapy of sepsis that facilitates the elimination of cytokines. HP-HF alternating with conventional hemofiltration is well tolerated. Further studies are needed to analyze whether HP-HF is able to mitigate the course of sepsis.

The utilisation of continuous veno-venous haemofiltration for the removal of septic mediators in patients with systemic inflammatory response syndrome

Septic shock is the leading cause of morbidity and mortality in critically ill patients. If the mediators responsible for the continuum of the sepsis cascade could be blocked or removed, patient outcome might improve. Researchers have been attempting to eliminate such mediators by continuous veno-venous haemofiltration (CVVH) but, despite over a decade of studies, many obstacles still remain. In this article, a comparison has been made of four similar research studies to ascertain any significant findings. Future research proposals have been considered in conjunction with the role the nurse within critical care might play in what could arguably be considered to be within the medical domain.

Cytokine dialysis: an ex vivo study

To test the hypothesis that dialysis using a new large pore membrane would achieve effective cytokine removal, blood from six volunteers was incubated with endotoxin (1 mg) and then circulated through a closed circuit with a polyamide membrane (nominal cut-off: 100 kDa). Hemodialysis was conducted at 1 or 9 L/hr of dialysate flow at the start of circulation and after 2 and 4 hours. The peak dialysate/plasma concentration ratios were 0.92 for interleukin (IL)-1beta, 0.67 for IL-6, 0.94 for IL-8, 0.33 for tumor necrosis factor (TNF)-a, and 0.11 for albumin. The dialysate/plasma ratios for all cytokines and albumin were decreased with increased dialysate flow from 1 to 9 L/hr (p < 0.05). Clearances for IL-1beta, IL-6, and IL-8, however, were significantly improved with increased dialysate flow (p < 0.01). There was no increase in TNF-a clearance (not significant) and a decrease in albumin clearance (p < 0.01). The peak clearance at 9 L/hr was 33 ml/min for IL-1beta, 19 for IL-6, 51 for IL-8, 11 for TNF-alpha, and 1.2 for albumin. No adsorption of cytokines was observed. We conclude that cytokine dialysis is achievable through a membrane with a high cut-off point with negligible albumin loss. These findings support the technical feasibility of this new approach to blood purification in sepsis.

Procalcitonin and proinflammatory cytokine clearance during continuous venovenous haemofiltration in septic patients

Procalcitonin (PCT), interleukin-6 (IL-6), tumour necrosis factor a (TNFalpha), and interleukin-1beta (IL-1beta) are important clinical prognostic markers in ICU septic patients. The goal of the study was to determine whether continuous venovenous haemofiltration (CWH), using an AN69 haemofilte, leads to elimination of PCT, TNFalpha, IL-6 and IL-1beta in 13 septic patients with multi-organ failure. At the start of haemofiltration (0), 6 and 12 hours the mean afferent plasma concentration +/- SD of PCT (10.1 +/- 9.1, 7 +/- 6, 5.9 +/- 5.7 ng/ml), IL-6 (804.6 +/- 847.6, 611.7 +/- 528.4, 575.2 +/- 539.2 pg/ml), and that of TNFalpha (4.5 +/- 2.6, 4 +/- 3.1, 3.8 +/- 2.9 pg/ml) significantly declined during CVVH. The efferent plasma concentrations were significantly lower than the corresponding afferent concentrations. PCT; IL-6 and TNFalpha were detectable in the ultrafiltrate of all patients. IL-1beta was only detectable in the plasma of eight patients and the ultrafiltrate of five patients. The plasma clearance of PCT, IL-6 and TNFalpha significantly decreased after 12 hours as a result of a decline in the adsorptive elimination of the mediators due to progressive membrane saturation. We demonstrated that if PCT, IL-6 and TNFalpha are used as clinical prognostic markers in septic patients who are treated with CWIH using an AN69 membrane, one should be aware that their plasma level could be modified by the therapy. In addition CWH could represent an appropriate tool to remove a broad spectrum of proinflammatory mediators, if such removal is required in septic patients.

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.

Cytokine removal with a large pore cellulose triacetate filter: an ex vivo study

OBJECTIVE

To test the hypothesis that hemofiltration using a new large pore cellulose triacetate hemofilter can achieve effective ultrafiltration of cytokines.

DESIGN

Ex-vivo study.

SETTING

Laboratory of Intensive Care Unit in tertiary hospital.

SUBJECTS

Six healthy volunteers.

INTERVENTIONS

Blood from 6 volunteers was incubated for 4 hours with 1 mg of endotoxin and then circulated through a closed hemofiltration circuit with a large pore cellulose triacetate hemofilter (nominal cut-off point: 60 kilodaltons). Hemofiltration was conducted at 1 L/h or 6 L/h of ultrafiltrate (UF) flow at the start of extra-corporeal circulation, and after 2 and 4 hours. Samples were taken from the arterial, venous and UF sampling ports.

MEASUREMENTS AND MAIN RESULTS

IL-Ibeta, IL-6, IL-8, IL-10, TNFalpha, and albumin were measured. Sieving coefficients (SC) above 0.6 were achieved for IL-Ibeta and IL-6 and SCs above 0.3 were achieved for IL-8 and TNF-alpha at 1 L/h. Sieving coefficients of all cytokines (except IL-10, p=0.22) were reduced when the ultrafiltration rate was increased from IL/h to 6 L/h (p<0.01), but the increase in ultrafiltration rate resulted in an overall increase in the clearance of all cytokines (p<0.001). The highest SC for albumin was 0.07 at 4 hours at 1 L/h, and fell to 0.01 at 6 L/h. The SCs for IL-8 fell at 4 hours (p<0.01), but the SCs for other cytokines did not change. No adsorption of cytokines and albumin was observed.

CONCLUSION

High volume hemofiltration (HVHF) using a new large pore cellulose triacetate filter achieved cytokine clearances greater than those reported with currently available hemo filters.

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.

Prospective evaluation of short-term, high-volume isovolemic hemofiltration on the hemodynamic course and outcome in patients with intractable circulatory failure resulting from septic shock

OBJECTIVE

To evaluate the effects of short-term, high-volume hemofiltration (STHVH) on hemodynamic and metabolic status and 28-day survival in patients with refractory septic shock.

DESIGN

Prospective, interventional.

SETTING

Intensive care unit (ICU), tertiary institution.

PATIENTS

Twenty patients with intractable cardiocirculatory failure complicating septic shock, who had failed to respond to conventional therapy.

INTERVENTIONS

STHVH, followed by conventional continuous venovenous hemofiltration. STHVH consisted of a 4-hr period during which 35 L of ultrafiltrate is removed and neutral fluid balance is maintained. Subsequent conventional continuous venovenous hemofiltration continued for at least 4 days.

MEASUREMENTS AND MAIN RESULTS

Cardiac index, systemic vascular resistance, pulmonary vascular resistance, oxygen delivery, mixed venous oxygen saturation, arterial pH, and lactate were measured serially. Fluid and inotropic support were managed by protocol. Therapeutic endpoints were as follows during STHVH: a) by 2 hrs, a > or =50% increase in cardiac index; b) by 2 hrs, a > or =25% increase in mixed venous saturation; c) by 4 hrs, an increase in arterial pH to >7.3; d) by 4 hrs, a > or =50% reduction in epinephrine dose. Patients who attained all four goals (11 of 20) were considered hemodynamic "responders"; patients who did not (9 of 20) were considered hemodynamic "nonresponders." There were no differences in baseline hemodynamic, metabolic, and Acute Physiology and Chronic Health Evaluation and Simplified Acute Physiology Scores between responders and nonresponders. Survival to 28 days was better among responders (9 of 11 patients) than among nonresponders (0 of 9). Factors associated with survival were hemodynamic-metabolic response status, time interval from ICU admission to initiation of STHVH, and body weight.

CONCLUSIONS

These data suggest that STHVH may be of major therapeutic value in the treatment of intractable cardiocirculatory failure complicating septic shock. Early initiation of therapy and adequate dose may improve hemodynamic and metabolic responses and 28-day survival.

Renal replacement therapies

Slow continuous renal replacement therapy is more hemodynamically stabilizing and is replacing conventional hemodialysis as the therapy of choice for acute renal failure in the intensive care unit. This article presents practical information, including basic terminology, basic physiology, technical aspects, and indications for and application of this technique.

Non-renal indications for continuous renal replacement therapy

While there is clear support for the use of continuous renal replacement therapy (CRRT) in critically ill acute renal failure patients, there are other illnesses without renal involvement where CRRT might be of value. These include sepsis and other inflammatory syndromes such as acute respiratory distress syndrome (ARDS) and cardiopulmonary bypass where removal of inflammatory mediators by hemofiltration is hypothesized to improve outcome. Adsorption appears to be the predominant mechanism of mediator elimination. However, the observed hemodynamic improvement can, at least partially, be attributed to a reduction of body temperature or to fluid removal, and the evidence for a clinically important removal of proinflammatory cytokines remains limited. Continuous and therefore smooth fluid removal may improve organ function in ARDS, after surgery with cardiopulmonary bypass, and in patients with refractory congestive heart failure. Continuous removal of endogenous toxins, eventually combined with intermittent hemodialysis, is probably beneficial in inborn errors of metabolism, severe lactic acidosis, or tumor lysis syndrome.

Hemofiltration treatment for sepsis: is it time for controlled trials?

While the use of hemofiltration to treat septic shock has potential benefits, the existing studies are difficult to compare because of their variety of inclusion criteria. The concept is to remove the various mediators of severe sepsis and septic shock, such as cytokines and eicosanoids, so that acute renal failure and the resultant multi-organ failure and possible death can be delayed or prevented. The dilemmas include: (a) hemofiltration cannot distinguish between these pro-inflammatory mediators as they are of similar molecular weights, and thus it is difficult to determine which one or combination should be eliminated for the best hemodynamics; (b) timing of the hemofiltration to remove a particular cytokine may make a difference in patient outcome; (c) the most efficacious convection rate of ultrafiltration has not been determined yet; (d) since these mediators quickly saturate the membrane, it should be frequently changed, and thus biocompatibility, availability and costs are added issues; (e) the choice of buffer is different according to the diagnosis of these critically ill patients. Before designing clinical trials, further experimentation is necessary to explore these problems.

A simple technique to perform combined ultrafiltration

To combine the advantages of conventional and modified ultrafiltration while keeping cardiopulmonary bypass technique simple, we have developed a simplified circuit of combined ultrafiltration, which is presently used in our pediatric patients. In addition to the benefits of combined ultrafiltration, this circuit allows the rewarming and prevention of heat loss in small children and neonates.

Acute renal failure in severely burned patients

Acute renal failure (ARF) is a well known complication of severe burns and is an important factor leading to an increase in mortality. In order to analyze possible pathogenetic and prognostic factors associated with ARF in burned patients we reviewed in a retrospective study the files of 328 patients with burns > 10% body surface area (BSA), admitted to our burn unit between 01.01.94 and 01.05.98. We found 48 patients with acute renal failure corresponding with an incidence of 14.6%. Patients with ARF had a mean burned surface area of 48% (13-95) and an abbreviated burn severity index score (ABSI) of 9.8 (4-15). Thirty eight (79%) of these patients had an inhalation injury diagnosed. Renal insufficiency was divided in a late and an early form depending on its time of onset and we found 15 (31%) patients with ARF occurring within the first 5 days of the hospital stay and 33 (69%) patients with ARF developing >5 days following the thermal injury. The incidence of myoglobinuria and hypotension during the resuscitation phase was significantly higher in the group with early ARF, whereas patients with late ARF presented sepsis more frequently than patients with early occurring renal failure. Accordingly, potential nephrotoxic antibiotics were administered more often in patients with late ARF. Patients with ARF were treated by continuous arteriovenous hemofiltration (CAVH) for a mean period of 10.5 days (1-47) and CAVH was associated with a complication rate of 10%. Most of the complications were associated with the vascular access in the femoral artery. The mortality rate in patients with ARF was 85% and death was due to multiple organ failure in 83% of the cases. Only burned BSA and inhalation injury proved to be significantly correlated with the development of ARF, whereas age, third degree burn or electric injury were not significantly different between the two groups. Neither age, TBSA, day of onset of ARF nor duration of the renal replacement therapy proved to be significantly different comparing survivors with non-survivors, and thus predictive for the survival rate.