Comparison of continuous arteriovenous hemofiltration and continuous arteriovenous dialysis in critically ill patients

ABO-incompatible kidney transplantation

PURPOSE OF REVIEW

A dramatic shortage of available organs around the world encouraged attempts to cross previously forbidden immunological boundaries in kidney transplantation. This review focuses on the recent results of ABO-incompatible kidney transplantation.

RECENT FINDINGS

The outcome of ABO-incompatible kidney transplantation in terms of patient and graft survival is comparable to ABO-compatible transplantation for adult and pediatric recipients. Splenectomy has been replaced by the B-cell-depleting agent rituximab to avoid isoagglutinin titer rebound, prevent antibody-mediated rejection, and improve graft survival. However, the risk for infections may be increased and warrants caution. Corticosteroids remain a necessary component of any ABO-incompatible protocol; early as well as late steroid withdrawal may bear an enhanced risk for acute rejection and should only be performed with careful follow-up including protocol biopsies. The few studies that have long-term outcomes using protocol biopsies have characterized a state of accommodation by up-regulation of complement inhibitors, down-regulation of A/B antigens, and establishment of endothelial chimerism over time.

SUMMARY

The experience accumulated around the world indicates that ABO-incompatible kidney transplantation is well tolerated and effective in adults and in children, and it represents an important step forward in expanding the living donor pool. Further understanding of ABO-incompatible graft accommodation may have broader implication also for human leukocyte antigen-sensitized allograft recipients.

Hemofiltration compared to hemodialysis for acute kidney injury: systematic review and meta-analysis

Introduction

The objective of this systematic review and meta-analysis was to determine the effect of renal replacement therapy (RRT), delivered as hemofiltration vs. hemodialysis, on clinical outcomes in patients with acute kidney injury (AKI).

Methods

MEDLINE, EMBASE and CENTRAL databases and conference abstracts were searched to June 2012 for parallel-group or crossover randomized and quasi-randomized controlled trials (RCTs) evaluating hemofiltration vs. hemodialysis in patients with AKI. Two authors independently selected studies and abstracted data on study quality and outcomes. Additional information was obtained from trial authors. We pooled data using random-effects models.

Results

Of 6,657 citations, 19 RCTs (10 parallel-group and 9 crossover) met inclusion criteria. Sixteen trials used continuous RRT. Study quality was variable. The primary analysis included three parallel-group trials comparing similar doses of hemofiltration and hemodialysis; sensitivity analyses included trials comparing combined hemofiltration-hemodialysis or dissimilar doses. We found no effect of hemofiltration on mortality (risk ratio (RR) 0.96, 95% confidence interval (CI) 0.73 to 1.25, P = 0.76; three trials, n = 121 (primary analysis); RR 1.10, 95% CI 0.88 to 1.38, P = 0.38; eight trials, n = 540 (sensitivity analysis)) or other clinical outcomes (RRT dependence in survivors, vasopressor use, organ dysfunction) compared to hemodialysis. Hemofiltration appeared to shorten time to filter failure (mean difference (MD) -7 hours, 95% CI (-19,+5), P = 0.24; two trials, n = 50 (primary analysis); MD -5 hours, 95% CI (-10, -1), P = 0.01; three trials, n = 113 (including combined hemofiltration-hemodialysis trials comparing similar doses); MD -6 hours, 95% CI (-10, -1), P = 0.02; five trials, n = 383 (sensitivity analysis)). Data primarily from crossover RCTs suggested that hemofiltration increased clearance of medium to larger molecules, including inflammatory cytokines, compared to hemodialysis, although almost no studies measured changes in serum concentrations. Meta-analyses were based on very limited data.

Conclusions

Data from small RCTs do not suggest beneficial clinical outcomes from hemofiltration, but confidence intervals were wide. Hemofiltration may increase clearance of medium to larger molecules. Larger trials are required to evaluate effects on clinical outcomes.

ABO blood group incompatibility: a diminishing barrier to successful kidney transplantation?

Blood type-incompatible transplantation has gained wide acceptance over the last decade. This is largely the result of B-cell-directed therapies aimed at modulating anti-blood group antibodies, which were the cause of the poor outcomes originally seen. Now rituximab (anti-CD20 and anti-B cell) has largely replaced splenectomy in preconditioning protocols, allowing for the wider implementation of ABO-incompatible transplants. Plasma exchange followed by intravenous immunoglobulin is also critical for the success of ABO-incompatible transplants. In this article, we describe the important contributions immunomodulatory drugs and antibody reduction therapies have made in achieving excellent outcomes in what was once an impenetrable barrier to transplantation.

Renal replacement therapy review: past, present and future

Support of renal function in modern times encompasses a wide array of methods and clinical scenarios, from the ambulatory patient to the critically ill. The ability to safely and routinely deliver ongoing organ support in the outpatient setting has until recently separated renal replacement therapy from other organ support. Renal replacement therapy (RRT) can be applied intermittently or continuously using extracorporeal (hemodialysis) or paracorporeal (peritoneal dialysis) methods. The purpose of this article is to familiarize the reader with the history, physiology, mode, dose, equipment and future of renal replacement therapy and not to detail the technical methods employed for blood purification.

High-dose renal replacement therapy for acute kidney injury: Systematic review and meta-analysis

OBJECTIVE

To determine the effect of renal replacement therapy dose on mortality and dialysis dependence in patients with acute kidney injury.

DATA SOURCES

MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials to October 2009; PubMed "Related Articles;" bibliographies of included trials; and additional information from trial authors.

STUDY SELECTION

Randomized and quasi-randomized, controlled trials in adults with acute kidney injury prescribed highvs. standard-dose continuous renal replacement therapy (> or =30 mL/kg/hr vs. <30 mL/kg/hr), intermittent hemodialysis, or sustained low-efficiency dialysis (daily vs. alternate day, or by target biochemistry).

DATA EXTRACTION

Three authors independently selected studies and extracted data on outcomes and study quality. Meta-analyses used random-effects models.

DATA SYNTHESIS

Of 5416 citations, 12 trials (n = 3999) met inclusion criteria. Modalities included continuous renal replacement therapy (7 trials), intermittent hemodialysis (3 trials), sustained low-efficiency dialysis (1 trial), and all three (1 trial). Study quality was moderate-high. Meta-analyses found no effect of high-dose renal replacement therapy on mortality (risk ratio, 0.89; 95% confidence interval, 0.77-1.03; 12 trials; n = 3954) or dialysis dependence among survivors (risk ratio, 1.15; 95% confidence interval, 0.92-1.44; 8 trials with events; n = 1743). The effect on mortality was similar (all interaction p values were nonsignificant) in patients with sepsis (risk ratio, 1.02; 95% confidence interval, 0.85-1.23; 9 trials; n = 1786) vs. without sepsis (risk ratio, 0.89; 95% confidence interval, 0.75-1.05; 8 trials; n = 1955), treated exclusively with continuous renal replacement therapy (risk ratio, 0.87; 95% confidence interval, 0.71-1.06; 7 trials; n = 2462) vs. other modalities alone or in combination (risk ratio, 0.92; 95% confidence interval, 0.70 -1.21; 5 trials; n = 1492), and in trials with low (risk ratio, 0.96; 95% confidence interval, 0.85-1.09; 6 trials; n = 3475) vs. higher (risk ratio, 0.76; 95% confidence interval, 0.53-1.09; 6 trials; n = 479) risk of bias.

CONCLUSIONS

High-dose renal replacement therapy in acute kidney injury does not improve patient survival or recovery of renal function overall or in important patient subgroups, including those with sepsis.

An improved affinity support and immunoadsorbent with a synthetic blood group oligosaccharide and polymer coating for hemoperfusion

An improved affinity support and an immunoadsorbent suitable for extracorporeal perfusion of whole blood (or plasma) are reported. The affinity support consists of calcined diatomite-type silica particles to which a synthetic oligosaccharide hapten, viz. A-trisaccharide representing human blood group A, with a linking spacer-arm is chemically attached. The immunoadsorbent thus obtained is surface-modified with a polymer coating. The modified immunoadsorbent is not hemolytic and shows no loss of biological activity in reducing antibody titers in vitro. An important feature of the improved immunoadsorbent is that the polymer coating provides a better surface resistance and therefore stability to the affinity support to prevent the release of potentially harmful fines. The usefulness of a physically stable support as an affinity adsorbent for the selective removal of specific antibodies or unwanted substances directly from the blood circulation by extracorporeal immunoadsorption has profound medical significance because this would provide an efficient but safe and practical alternative to therapeutic intervention using plasma exchange or plasma perfusion, both of which require plasmapheresis.

Continuous haemodiafiltration during and after cardiopulmonary bypass in renal failure patients

PURPOSE

Continuous haemodiafiltration (CHDF) is a technique enhancing the efficiency of solute clearance of haemofiltration by infusing dialysis fluid through the haemofilter. It has been reported to control water and electrolyte balance continuously without haemodynamic instability in critically ill patients with renal failure, Therefore, we used CHDF during and after cardiopulmonary bypass (CPB) in two renal failure patients, and discuss its efficacy.

CLINICAL FEATURES

The first patient undergoing aortic valve replacement had dialysis-dependent renal failure. Chronic renal failure in the second patient undergoing mitral valve replacement and coronary revascularization was controlled preoperatively with diuretics. In both cases, CHDF was performed not only during CPB but also in the post-CPB period. Serum concentrations of potassium, urea and creatinine were well-controlled in spite of large amount of blood transfused in the post-CPB period (1000 ml fresh blood and 400 ml fresh frozen plasma in the fist patient, and 1400 ml fresh blood in the second patient). There was no difficulty in haemostasis during the use of nafamostat mesilate as an anticoagulant to keep activated clotting time at about 150 sec for CHDF in the post-CPB period.

CONCLUSION

Our initial experiences of CHDF during and after CPB suggest that the technique provides excellent electrolyte, metabolite and fluid management for the cardiac patients with chronic renal failure. Combined with nafamostat mesilate for anticoagulation, CHDF was simple and safe and did not increase the risk of bleeding.

A review of continuous renal replacement therapy

Patients in the Intensive Care Unit commonly develop acute renal failure (ARF). The kidneys are rarely the only organs failing in these patients. Frequently ARF is part of multiple organ dysfunction syndrome. The choice of dialytic therapy should consider, not only the efficacy of the therapy, but also the undesirable effects such therapy may have on the other failing organs. Intermittent Haemodialysis and Peritoneal Dialysis were the conventional forms of dialysis available. Both are associated with complications which may make them unsuitable for use in the haemodynamically unstable, hypercatabolic patients, seen in the Intensive Care setting. Continuous Renal Replacement Therapy (CRRT) has been introduced in many Intensive Care Units to provide a more stable, flexible form of dialysis. The purpose of this article is to give an overview of the various forms of CRRT and to discuss the advantages of this form of therapy.

Acute continuous hemodiafiltration: a prospective study of 110 patients and a review of the literature

One hundred ten critically ill patients with acute renal failure receiving acute continuous hemodiafiltration (ACHD) in our intensive care unit were studied prospectively. Acute continuous hemodiafiltration consisted either of continuous arteriovenous hemodiafiltration or of continuous veno-venous hemodiafiltration, and was used for 17,817 hours (mean duration of patient treatment, 161.9 hours), resulting in a fall from a mean pre-ACHD urea of 35.7 mmol/L to a plateau value of 16.8 mmol/L at 72 hours of treatment. The mean urea clearance achieved was 24.9 mL/min. Eighty of these patients (72.7%) were receiving artificial ventilation at the time of ACHD and 45 (40.9%) had more than four failing organs. The mean APACHE II score was 27.7. Despite the degree of illness severity, 42 patients (32.2%) survived to discharge from hospital. The use of ACHD was associated with hemodynamic stability, rapid normalization of electrolytes, and the ability to freely administer drugs, blood, and/or blood products. It also allowed for maintenance of an aggressive, nitrogen-rich, nutritional regimen. Support of these critically ill patients with acute renal failure using ACHD was achieved safely and without the employment of additional dialysis-trained nursing staff. Our own experience and a review of the available literature strongly suggest that the advantages associated with the use of ACHD therapies are clinically significant and support the view that ACHD is a modality of renal replacement most suited to critically ill patients with acute renal failure.

Continuous arteriovenous haemodialysis and haemofiltration in intensive care acute renal failure patients

CAVHD and CAVH were compared regarding uraemic control in 13 critically ill intensive care patients with acute renal failure (ARF). Patients' mean age was 60 years. Pretreatment blood urea range was 17-56 mmol/l (33-56 mmol/l in 70% of the patients). All patients received vasopressor drugs, and 92% were on artificial mechanical respiration. From the results of this study both modalities gave adequate uraemic control. There was a notable decrease in the urea and creatinine levels with CAVHD more than with CAVH. There was no statistically significant difference between the two modalities in the urea clearance. However, a significant difference (P < 0.05) in creatinine was obtained with CAVHD. Our results suggest that CAVHD is a useful alternative to CAVH in ARF especially when the blood urea level is > 30 mmol/l. However, a higher dialysate flow rate (e.g. 25 ml/min) should be used if the urea level is more than 40 mmol/l. CAVH should be reserved for ARF patients in whom fluid overload is a major problem.

Continuous arteriovenous haemofiltration in children

Continuous arteriovenous haemofiltration (CAVH) was used in 7 critically ill children: a premature neonate with hypervolaemia secondary to hydrops foetalis and six children aged 9 days to 7 years with acute oliguric renal failure. Biospal 0.5 m2, Renaflo 0.25 m2, Gambro 0.15 m2 and Amicon 0.015 m2 filters were used according to the weights and ages of the patients. Adequate removal of water and solutes was obtained in 6 patients. One of the patients with the smallest filter needed a change to a filter with a larger surface area to improve water and solute removal. Haemofiltration was maintained for between 17 hours and 31 days and was well tolerated. CAVH was discontinued because of recovery of renal function in three patients, improvement of the hypervolaemic state in one, death in three, and transfer to continuous ambulatory peritoneal dialysis because of chronic renal failure in one patient. CAVH is a useful technique for the treatment of acute renal failure and hypervolaemia in critically ill children.