Biocompatible membranes in acute renal failure: prospective case-controlled study

Determinants of Outcomes of Acute Kidney Injury: Clinical Predictors and Beyond

Acute kidney injury (AKI) is a common clinical syndrome characterized by rapid impairment of kidney function. The incidence of AKI and its severe form AKI requiring dialysis (AKI-D) has been increasing over the years. AKI etiology may be multifactorial and is substantially associated with increased morbidity and mortality. The outcome of AKI-D can vary from partial or complete recovery to transitioning to chronic kidney disease, end stage kidney disease, or even death. Predicting outcomes of patients with AKI is crucial as it may allow clinicians to guide policy regarding adequate management of this problem and offer the best long-term options to their patients in advance. In this manuscript, we will review the current evidence regarding the determinants of AKI outcomes, focusing on AKI-D.

Protective Role of the Portocaval Shunt in Liver Transplantation

BACKGROUND

Advances in medical management and surgical technique have resulted in stepwise improvements in early post-transplant survival rates. Modifications in the surgical technique, such as the realization of the portocaval shunt (PCS), could influence survival rates. The aim of this study was to evaluate the mortality rate for 12 months after liver transplantation, analyzing the causes and risk factors related to its development and assessing the impact that PCS could have on them.

METHODS

A total of 231 recipients were included in the retrospective, longitudinal, and nonrandomized study.

RESULTS

The overall survival of the transplant was 85.2% (197 patients). The most frequent cause of death was infection (38.2%), followed by the multiorgan failure of multiple etiology (23.5%). Most of the risk factors related to mortality correspond to variables of the postoperative period. The results of the multivariate analysis identified the main risk factors for death: the presence of surgical complications and the need for renal replacement therapy. In contrast, the performance of PCS exerted a protective effect, reducing the probability of death by 70%.

CONCLUSIONS

Despite the good results obtained in several studies, there is still debate regarding the benefit of its realization. In our study, PCS was a factor associated with a reduction in mortality, with a markedly lower probability of adverse events. However, we agree with other authors on the need for larger and randomized studies to adequately determine the validity of such results.

The Japanese clinical practice guideline for acute kidney injury 2016

Acute kidney injury (AKI) is a syndrome which has a broad range of etiologic factors depending on different clinical settings. Because AKI has significant impacts on prognosis in any clinical settings, early detection and intervention is necessary to improve the outcomes of AKI patients. This clinical guideline for AKI was developed by a multidisciplinary approach with nephrology, intensive care medicine, blood purification, and pediatrics. Of note, clinical practice for AKI management which was widely performed in Japan was also evaluated with comprehensive literature search.

The Japanese Clinical Practice Guideline for acute kidney injury 2016

Acute kidney injury (AKI) is a syndrome which has a broad range of etiologic factors depending on different clinical settings. Because AKI has significant impacts on prognosis in any clinical settings, early detection and intervention are necessary to improve the outcomes of AKI patients. This clinical guideline for AKI was developed by a multidisciplinary approach with nephrology, intensive care medicine, blood purification, and pediatrics. Of note, clinical practice for AKI management which was widely performed in Japan was also evaluated with comprehensive literature search.

Modulation of CD11b/CD18 on Monocytes and Granulocytes following Hemodialysis Membrane Interaction in vitro

We studied the generation of CD11b/CD18 mobilizing factors in serum after incubation with dialysis membrane fragments of different chemical composition. We also evaluated the relative importance of the alternative and classical pathways of the complement system in the generation of such factors. Monocytes and granulocytes from healthy blood donors were incubated in normal human serum (NHS) and in NHS that had been preincubated with Cuprophan (CU) membrane (NHS-CU), Hemophan (HE) (NHS-HE) or polysulfone (PS) (NHS-PS). NHS-CU caused the highest up-regulation of the CD11b/CD18 receptor on monocytes and granulocytes. The rank in capacity to mobilize CD11b/CD18 on granulocytes was CU>HE>PS (p<0.001), CU>HE (p<0.05) and HE>PS (p<0.001). The rank in capacity to mobilize CD11b/CD18 on monocytes was CU>HE>PS (p<0.001), CU>HE (p<0.05) and HE>PS (p<0.01). NHS-PS induced a lower up-regulation of CD11b/CD18 compared to NHS which indicates that serum factors with the ability to mobilize the CD11b/CD18 receptor on monocytes and granulocytes are deposited on or adsorbed by PS. In order to study the relative contribution of the alternative and classical pathways of the complement system in the generation of CD11b/CD18 mobilizing factors in serum, three different serum preparations (1. both pathways intact. 2. only the alternative intact and 3. only the classical pathway intact) were used. The CU membrane activated the classical pathway to a larger extent than the PS membrane (p<0.01). When only the alternative pathway was intact no difference in the generation of CD11b/CD18 mobilizing factors between the CU and PS membranes was observed. These studies show that CD11b/CD18 mobilizing serum factors are generated after incubation with CU membranes and that such factors are probably adsorbed by PS. The classical pathway of complement activation seems to contribute to the generation of CD11b/CD18 mobilizing factors in serum.

Issues of Acute Kidney Injury Staging and Management in Sepsis and Critical Illness: A Narrative Review

Acute kidney injury (AKI) has a high incidence on intensive care units around the world and is a major complication in critically ill patients suffering from sepsis or septic shock. The short- and long-term complications are thereby devastating and impair the quality of life. Especially in terms of AKI staging, the determination of kidney function and the timing of dialytic AKI management outside of life-threatening indications are ongoing matters of debate. Despite several studies, a major problem remains in distinguishing between beneficial and unnecessary "early" or even harmful renal replacement therapy (RRT). The latter might prolong disease course and renal recovery. AKI scores, however, provide an insufficient outcome-predicting ability and the related estimation of kidney function via serum creatinine or blood urea nitrogen (BUN)/urea is not reliable in AKI and critical illness. Kidney independent alterations of creatinine- and BUN/urea-levels further complicate the situation. This review critically assesses the current AKI staging, issues and pitfalls of the determination of kidney function and RRT timing, as well as the potential harm reflected by unnecessary RRT. A better understanding is mandatory to improve future study designs and avoid unnecessary RRT for higher patient safety and lower health care costs.

A sandwich-type zinc complex from a rhodamine dye based ligand: a potential fluorescent chemosensor for acetate in human blood plasma and a molecular logic gate with INHIBIT function

Zn-R1 exhibits reversible binding with acetate yielding different optical and fluorescence outputs on alternate addition of zinc and acetate ions.

Renal replacement therapy in adult and pediatric intensive care : Recommendations by an expert panel from the French Intensive Care Society (SRLF) with the French Society of Anesthesia Intensive Care (SFAR) French Group for Pediatric Intensive Care Emergencies (GFRUP) the French Dialysis Society (SFD)

Acute renal failure (ARF) in critically ill patients is currently very frequent and requires renal replacement therapy (RRT) in many patients. During the last 15 years, several studies have considered important issues regarding the use of RRT in ARF, like the time to initiate the therapy, the dialysis dose, the types of catheter, the choice of technique, and anticoagulation. However, despite an abundant literature, conflicting results do not provide evidence on RRT implementation. We present herein recommendations for the use of RRT in adult and pediatric intensive care developed with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system by an expert group of French Intensive Care Society (SRLF), with the participation of the French Society of Anesthesia and Intensive Care (SFAR), the French Group for Pediatric Intensive Care and Emergencies (GFRUP), and the French Dialysis Society (SFD). The recommendations cover 4 fields: criteria for RRT initiation, technical aspects (access routes, membranes, anticoagulation, reverse osmosis water), practical aspects (choice of the method, peritoneal dialysis, dialysis dose, adjustments), and safety (procedures and training, dialysis catheter management, extracorporeal circuit set-up). These recommendations have been designed on a practical point of view to provide guidance for intensivists in their daily practice.

Effects of renal replacement therapy on renal recovery after acute kidney injury

Recovery of kidney function following an episode of acute kidney injury (AKI) is now acknowledged as a vital patient-centered outcome with clear health economic implications. In approximately 5-8% of critically ill patients with more severe forms of AKI, support with renal replacement therapy (RRT) is provided. Recent data have suggested that rates of RRT utilization in AKI are increasing. Despite advances in our understanding of how best to prescribe acute RRT in critically ill patients with AKI, additional aspects remain uncertain, predisposing to suboptimal delivery and variation in practice. Importantly, if, when, how, and by what principles we apply acute RRT for AKI are all treatment decision-related factors that are modifiable and may interact with recovery of kidney function. Limited data, mostly from observational studies and secondary analyses, have explored the specific association between acute RRT and recovery. Available data are not able to clarify whether providing any RRT in otherwise eligible patients with AKI impacts recovery. They are also unable to inform whether the timing or circumstance under which RRT is started impacts recovery. No studies have evaluated whether there is an optimal time to start RRT to maximize the probability of recovery. Accumulated evidence, mostly derived from observational studies, suggests initial therapy in critically ill patients with AKI with continuous RRT, compared with intermittent modalities, improves the probability of recovery to dialysis independence. Evidence from high-quality randomized trials failed to show any association between delivered dose intensity of RRT and recovery. The use of biocompatible membranes for acute RRT may improve recovery in AKI; however, data are inconsistent. Limited data have evaluated the impact of membrane flux properties on recovery. Preliminary data have suggested that circuit anticoagulation with citrate, which results in a reduction in membrane-induced oxidative stress and leukocyte activation, may be associated with improved recovery; however, further corroborative data are needed. Additional evidence, ideally from randomized trials, is clearly needed to inform best practice in the delivery of acute RRT to optimize probability of recovery of kidney function for survivors of AKI.

Platelet Consumption and Filter Clotting Using Two Different Membrane Sizes during Continuous Venovenous Haemodiafiltration in the Intensive Care Unit

Background. The aim of this study was to investigate whether different haemofilter surface areas affect clotting and platelet consumption in critically ill patients undergoing continuous venovenous haemodiafiltration (CVVHDF). Methods. CVVHDF was performed in postdilution technique using a capillary haemofilter with two different membrane sizes, Ultraflux AV 1000S (n = 17, surface 1.8 m², volume 130 mL), and the smaller AV 600S (n = 16, surface 1.4 m², volume 100 mL), respectively. Anticoagulation was performed with heparin. Results. No significant differences were found when the two filters were compared. CVVHDF was performed for 33 (7–128) hours with the filter AV 1000S and 39 (7–97) hours with AV 600S (P = 0.68). Two (1–4) filters were utilised in both groups over this observation period (P = 0.94). Platelets dropped by 52,000 (0–212,000) in AV 1000S group and by 89,500 (0–258,000) in AV 600S group (P = 0.64). Haemoglobin decreased by 1.2 (0–2.8) g/dL in AV 1000S group and by 1.65 (0–3.9) g/dL in AV 600S group (P = 0.51), leading to the transfusion of 1 (0–4) unit of blood in 19 patients (10 patients with AV 1000S and 9 with AV 600S). Filter observation was abandoned due to death (12.1%), need for systemic anticoagulation (12.1%), repeated clotting (36.4%), and recovery of renal function (39.4%). Conclusion. Our study showed that a larger filter surface area did neither reduce the severity of thrombocytopenia and anaemia, nor decrease the frequency of clotting events.

The role of the complement system in acute kidney injury

Acute kidney injury is a common and severe clinical problem. Patients who develop acute kidney injury are at increased risk of death despite supportive measures such as hemodialysis. Research in recent years has shown that tissue inflammation is central to the pathogenesis of renal injury, even after nonimmune insults such as ischemia/reperfusion and toxins. Examination of clinical samples and preclinical models has shown that activation of the complement system is a critical cause of acute kidney injury. Furthermore, complement activation within the injured kidney is a proximal trigger of many downstream inflammatory events within the renal parenchyma that exacerbate injury to the kidney. Complement activation also may account for the systemic inflammatory events that contribute to remote organ injury and patient mortality. Complement inhibitory drugs have now entered clinical use and may provide an important new therapeutic approach for patients suffering from, or at high risk of developing, acute kidney injury.

Cell therapy, advanced materials, and new approaches to acute kidney injury

Acute renal failure (ARF) is a common clinical syndrome characterized by an abrupt deterioration in kidney function, resulting in abnormalities in volume-regulatory, metabolic-regulatory, excretory, and endocrine functions. Despite decades of improvements in the provision of intensive care, and specifically in the provision of renal replacement therapy, the morbidity and mortality associated with acute kidney injury (AKI) remain extremely high. This article highlights novel cell therapies, advanced materials, and approaches to AKI with the aim of illuminating a potential path for future basic, translational, and clinical research using these novel modalities.

Nutritional support for acute kidney injury

BACKGROUND

Treatment for acute kidney Injury (AKI) primarily relies on treating the underlying cause and maintaining the patient until kidney function has recovered. Enteral and parenteral nutrition are commonly used to treat nutritional disorders in AKI patients, however their efficacy in treating AKI are still debated. This review was first published in 2010.

OBJECTIVES

To evaluate the effectiveness and safety of nutritional support for patients with AKI.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Chinese Biomedical Disc, VIP and China National Knowledge Infrastructure (CNKI).Date of last search: 4 July 2012

SELECTION CRITERIA

All randomised controlled trials (RCTs) reported for AKI and nutrition were included.

DATA COLLECTION AND ANALYSIS

Authors independently assessed study quality and extracted data. Results were expressed as risk ratio (RR) with 95% confidence intervals (CI) or mean difference (MD).

MAIN RESULTS

Eight studies (257 participants) were included. An overall pooled analysis was not performed due to the different interventions used and different outcomes measured. Selection bias was not reported (unclear) in six studies and was adequately reported (low) for random sequence generation in two studies. Participant/personnel blinding was adequately reported in one study and unclear in seven. Incomplete outcome reporting bias was low in six studies and high in two. Selective reporting was low in six studies, unclear in one study, and high in one study. No other biases were detected. There was a significant increase in recovery rate for AKI (RR 1.70, 95% CI 1.70 to 2.79) and survival in dialysed patients (RR 3.56, 95% CI 0.97 to 13.08) for intravenous essential L-amino acids (EAA) compared to hypertonic glucose alone. Compared to lower calorie-total parenteral nutrition (TPN), higher calorie-TPN did not improve estimated nitrogen balance, protein catabolic rate, or urea generation rate; but increased serum triglycerides, glucose, insulin need and nutritional fluid administration. There was no difference between groups in estimated nitrogen balance, but there were differences between urea nitrogen appearance (MD 0.98, 95% CI 0.25 to 1.71) and net protein utilisation (MD 21.50%, 95% CI 0.39 to 42.61). Urea nitrogen appearance was lower in the low nitrogen intake group than in the high nitrogen intake group. There was no significant difference in death between EAA and general amino acids (GAA) (RR 1.52, 95% CI 0.63 to 3.68). High dose amino acids did not improve cumulative water excretion, furosemide requirement, nitrogen balance or death compared to normal dose amino acids. Glucose+EAA+histidin had better nitrogen balance than glucose+GAA; glucose+nitrogen+fat significantly increased serum creatinine compared with glucose+GAA; glucose+EAA+histidin significantly improved nitrogen balance, U/P urea and serum creatinine, but increased plasma urea compared to glucose+nitrogen+fat.

AUTHORS' CONCLUSIONS

There was insufficient evidence found to support the effectiveness of nutritional support for AKI. Further high quality studies are required to provide reliable evidence of the effect and safety of nutritional support.

In vivo evaluation of the biocompatibility of surface modified hemodialysis polysulfone hollow fibers in rat

Polysulfone (Psf) hollow fiber membranes (HFMs) have been widely used in blood purification but their biocompatibility remains a concern. To enhance their biocompatibility, Psf/TPGS (d-α-tocopheryl polyethylene glycol 1000 succinate) composite HFMs and 2-methacryloyloxyethyl phosphorylcholine (MPC) coated Psf HFMs have been prepared. They have been evaluated for in vivo biocompatibility and graft acceptance and compared with sham and commercial membranes by intra-peritoneal implantation in rats at day 7 and 21. Normal body weights, tissue formation and angiogenesis indicate acceptance of implants by the animals. Hematological observations show presence of post-surgical stress which subsides over time. Serum biochemistry results reveal normal organ function and elevated liver ALP levels at day 21. Histological studies exhibit fibroblast recruitment cells, angiogenesis and collagen deposition at the implant surface indicating new tissue formation. Immuno-histochemistry studies show non-activation of MHC molecules signifying biocompatibilty. Additionally, Psf/TPGS exhibit most favorable tissue response as compared with other HFMs making them the material of choice for HFM preparation for hemodialysis applications.

Acute kidney injury in the intensive care unit

Acute kidney injury (AKI) is a common clinical syndrome with a broad aetiological profile. It complicates about 5% of hospital admissions and 30% of admissions to intensive care units (ICU). During last 20 years has been a significant change in the spectrum of severe AKI such that it is no longer mostly a single organ phenomenon but rather a complex multisystem clinical problem. Despite great advances in renal replacement technique (RRT), mortality from AKI, when part of MOF, remains over 50%. The changing nature of AKI requires a new approach using the new advanced technology. Clinicians can provide therapies tailored to time constraints (intermittent, continuous, or extended intermittent), haemodynamic, and metabolic requirements and aimed at molecules of variable molecular weight. Peritoneal dialysis (PD) is technically the simplest form of RRT and is still commonly used worldwide. The problems include difficulty in maintaining dialysate flow, peritoneal infection, leakage, protein losses, and restricted ability to clear fluid and uraemic wastes. PD is the preferred treatment modality for AKI in pediatric practice. Patients that are hemodynamically stable can be managed with intermittent hemodialysis (IHD), whereby relatively short (3 to 4 h) dialysis sessions may be performed every day or every other day. Patients who are haemodynamically unstable are best managed using continuous renal replacement therapies (CRRT), which allow for continuous fine-tuning of intravascular volume, easier correction of hypervolemia, better solute removal, more accurately correction of metabolic acidosis, and offers possibilities for unlimited energy support. Recently, "hybrid" or sustained low-efficiency dialysis (SLED) was introduced as a method which combines the advantages of IHD with those of CRRT. In this technique, classic dialysis hardware is used at low blood and dialysate flow rates, for prolonged period of time (6 to 12 h/day). SLED offers more haemodynamic stability, better correstion of hypervolaemia, and more adequate solue removal, compared with IHD. In conclusion, AKI in the ICU is increasingly a component of sepsis and MSOF, and the development of rational strategies for initiation, dosing, and effective delivery of RRT in this setting is among the greatest challenges facing nephrologists and intensivists today.

The dark side of high-intensity renal replacement therapy of acute kidney injury in critically ill patients

The impact of intensity or dose of renal replacement therapy (RRT) on outcome of critically ill patients has been a matter of controversy. Most definitions of an adequate dose of acute RRT are based on urea removal, while ignoring other crucial aspects of RRT adequacy in acute kidney injury (AKI). Although some clinical trials have found an improvement in survival with higher doses of intermittent hemodialysis or continuous RRT, results have not been consistent across all studies. The largest trials suggest that there is no additional survival benefit with doses of 35-45 ml/kg/h (CRRT) or daily intermittent hemodialysis. On the other hand, high-intensity treatment may cause life-threatening complications and thereby counteract the benefits of higher small-solute clearance. One important area for future investigations is the need to characterize the potential harm of high-dose RRT for AKI in critically ill patients.

Nutritional support for acute kidney injury

BACKGROUND

Treatment for acute kidney Injury (AKI) primarily relies on treating the underlying cause and maintaining the patient until kidney function has recovered. Enteral and parenteral nutrition are commonly used to treat nutritional disorders in AKI patients, however their efficacy in treating AKI are still debated.

OBJECTIVES

To evaluate the effectiveness and safety of nutritional support for patients with AKI.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Chinese Biomedical Disc, VIP and China National Knowledge Infrastructure (CNKI).

SELECTION CRITERIA

All randomised controlled trials (RCTs) reported for AKI and nutrition were included.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed study quality and extracted data. Results were expressed as risk ratio (RR) with 95% confidence intervals (CI) or mean difference (MD).

MAIN RESULTS

Eight studies (257 participants) were included. An overall pooled analysis was not performed due to the different interventions used and different outcomes measured. There was a significant increase in recovery rate for AKI (RR 1.70, 95% CI 1.70 to 2.79) and survival in dialysed patients (RR 3.56, 95% CI 0.97 to 13.08) for intravenous essential L-amino acids (EAA) compared to hypertonic glucose alone. Compared to lower calorie-total parenteral nutrition (TPN), higher calorie-TPN did not improve estimated nitrogen balance, protein catabolic rate, or urea generation rate, but increased serum triglycerides, glucose, insulin need and nutritional fluid administration. There was no difference between groups in estimated nitrogen balance, but there were differences between urea nitrogen appearance (MD 0.98, 95% CI 0.25 to 1.71) and net protein utilisation (MD 21.50%, 95% CI 0.39 to 42.61). Urea nitrogen appearance was lower in the low nitrogen intake group than in the high nitrogen intake group. There was no significant difference in death between EAA and general amino acids (GAA) (RR 1.52, 95% CI 0.63 to 3.68). High dose amino acids did not improve cumulative water excretion, furosemide requirement, nitrogen balance or death compared to normal dose amino acids. Glucose+EAA+histidin had better nitrogen balance than glucose+GAA; glucose+nitrogen+fat significantly increased serum creatinine compared with glucose+GAA; glucose+EAA+histidin significantly improved nitrogen balance, U/P urea and serum creatinine, but increased plasma urea compared to glucose+nitrogen+fat.

AUTHORS' CONCLUSIONS

There is not enough evidence to support the effectiveness of nutritional support for AKI. Further high quality studies are required to provide reliable evidence of the effect and safety of nutritional support.

Effect of hemodialysis before transplant surgery on renal allograft function--a pair of randomized controlled trials

BACKGROUND

Hemodialysis immediately before kidney transplant surgery has been suggested to adversely affect early graft function. On the other hand, considering its profound antiinflammatory effects, a beneficial impact of regional citrate anticoagulation on the evolution of graft function can be speculated. We sought to assess the clinical impact of preoperative hemodialysis and dialysis anticoagulation in two related randomized trials.

METHODS

Eligible kidney transplant candidates with a serum potassium less than or equal to 5.0 mEq/L were randomized to receive dialysis or no dialysis before deceased donor transplantation. Patients with a potassium more than 5.0 mEq/L were randomized to receive dialysis with heparin or citrate anticoagulation. The primary endpoint was the estimated glomerular filtration rate (eGFR) at posttransplant day 5.

RESULTS

The first comparison (56 vs. 54 patients) revealed no effect of dialysis on eGFR at day 5 (primary endpoint, 12 [interquartile range 5-36] vs. 13 [5-37] mL/min/1.73 m2, P=0.98), rates of delayed graft function (22% vs. 27%, P=0.66), cellular rejection (20% vs. 24%, P=0.65), and C4d-positive dysfunction (2% vs. 9%, P=0.11) or 1-year death-censored graft survival (89% vs. 91%, P=0.51). Comparing citrate with heparin anticoagulation (44 vs. 66 patients), no differences in eGFR at day 5 (17 [8-31] vs. 14 [6-38] ml/min/1.73 m2, P=0.57), delayed graft function (21% vs. 30%, P=0.28), cellular rejection (23% vs. 33%, P=0.29), and graft survival (90% vs. 88%, P=0.44) were found. For citrate anticoagulation, less C4d-positive rejection episodes (P=0.08) and higher 1-year eGFR levels (P=0.03) were observed.

CONCLUSION

Pretransplant hemodialysis and anticoagulation may not affect early graft function in a meaningful way.

Evaluation of "Loss" and "End stage renal disease" after acute kidney injury defined by the Risk, Injury, Failure, Loss and ESRD classification in critically ill patients

PURPOSE

The Risk, Injury, Failure, Loss and ESRD (RIFLE) classification has been widely accepted for the definition of acute kidney injury (AKI); however, no study has described in detail the last two stages of the classification: "Loss" and "ESRD". We aim to describe and evaluate the development of "Loss" and "ESRD" in a group of critically ill patients.

METHODS

We conducted a retrospective analysis of cases prospectively collected from the Acute Physiology and Chronic Health Assessment (APACHE III) database. Subjects were consecutive critically ill patients >18 years of age admitted to three ICUs of two tertiary care academic hospitals, from January 2003 through August 2006, excluding those who denied research authorization, chronic hemodialysis therapy, kidney transplant recipients, readmissions, and admissions for less than 12 h for low risk monitoring.

RESULTS

11,644 patients were included in the study. The median age was 66 (interquartile range, 52-76), 90% were Caucasians and 54% of the patients were male. Half of the patients developed AKI, and most of the patients were in the Risk and Injury stages. From the patients that developed AKI, a total of 1,065 (19%) patients required renal replacement therapy (RRT), 415 (39%) underwent continuous renal replacement therapy (CRRT) and 650 (61%) underwent intermittent hemodialysis. A total of 281 patients on RRT did not survive hospital discharge, 97 patients progressed to "Loss", and 282 patients progressed to "ESRD". After multivariable adjustment, the progression to "ESRD" was associated with higher baseline creatinine, odds ratio (OR) 1.19 per every increase in creatinine of 0.1 mg/dl (95% CI, 1.11-1.29) P < 0.001; and less frequent use of CRRT, OR 0.18 (95% CI, 0.11-0.29) P < 0.001.

CONCLUSION

In this large retrospective study we found that almost 50% developed some form of AKI as defined by the RIFLE classification. Of these, 19% required RRT, and 4.9% progressed to "ESRD". "ESRD" was more likely in patients with elevated baseline creatinine and those treated with intermittent hemodialysis.

Management of acute renal failure in the elderly patient: a clinician's guide

Numerous anatomical and functional changes occurring in the aging kidney lead to reduced glomerular filtration rate, lower renal blood flow and impaired renal autoregulation. The elderly are especially vulnerable to the development of renal dysfunction and in this population acute renal failure (ARF) is a common problem. ARF is often iatrogenic and multifactorial; common iatrogenic combinations include pre-existing renal dysfunction and exposure to nephrotoxins such as radiocontrast agents or aminoglycosides, use of NSAIDs in patients with congestive cardiac failure and use of ACE inhibitors and diuretics in patients with underlying atherosclerotic renal artery stenosis. The aetiology of ARF is classically grouped into three categories: prerenal, intrinsic and postrenal. Prerenal ARF is the second most common cause of ARF in the elderly, accounting for nearly one-third of all hospitalized cases. Common causes can be grouped into true volume depletion (e.g. decreased fluid intake), decreased effective blood volume (e.g. systemic vasodilation) and haemodynamic (e.g. renal artery stenosis, NSAID use). Acute tubular necrosis (ATN) is the most common cause of intrinsic ARF and is responsible for over 50% of ARF in hospitalized patients, and up to 76% of cases in patients in intensive care units. ATN usually occurs after an acute ischaemic or toxic event. The pathogenesis of ATN involves an interplay of processes that include endothelial injury, microvascular flow disruption, tubular hypoxia, dysfunction and apoptosis, tubular obstruction and trans-tubular back-leak. Vasculitis causing ARF should not be missed as this condition is potentially life threatening. The likelihood of a postrenal cause for ARF increases with age. Benign prostatic hypertrophy, prostatic carcinoma and pelvic malignancies are all important causes. Early identification of ARF secondary to obstruction with renal imaging is essential, and complete or partial renal recovery usually ensues following relief of the obstruction.A comprehensive medical and drug history and physical examination are all invaluable. Particular attention should be paid to the fluid status of the patient (skin turgor, jugular venous pressure, lying and standing blood pressure, urine output). Urinalysis should be performed to detect evidence of proteinuria and haematuria, which will aid diagnosis. Fractional excretion of sodium and urine osmolality may be measured but the widespread use of diuretics in the elderly gives rise to unreliable results. Renal imaging, usually ultrasound scanning, is routinely performed for assessment of renal size and to exclude urinary obstruction. In some cases, renal biopsy is necessary to provide specific diagnostic information. The general principles of managing ARF include treatment of life-threatening features such as shock, respiratory failure, hyperkalaemia, pulmonary oedema, metabolic acidosis and sepsis; stopping and avoiding administration of nephrotoxins; optimization of haemodynamic and fluid status; adjustment of drug dosage appropriate to glomerular filtration rate; early nutritional support; and early referral to nephrologists for diagnosis of ARF cause, timely initiation of dialysis and initiation of specific treatment. The treatment of prerenal and ATN ARF is largely supportive with little evidence of benefit from current pharmacological therapies. Despite advances in critical care medicine and renal replacement therapy, the mortality of ARF has not changed significantly over the last 40 years, with current mortality rates being up to 75%.

Intermittent versus continuous renal replacement therapy: a matter of controversy

BACKGROUND

Acute Renal Failure (ARF) requiring some form of replacement therapy is a frequent complication in the critically ill patient. Despite potential therapeutic advantages the expectation of an improvement in patient outcomes using Continuous Renal Replacement Therapy (CRRT) compared to conventional Intermittent Haemodialysis (IHD) remains controversial.

AIMS AND METHOD

This article will review the literature on the issues surrounding the use of IHD versus CRRT in the management of the critically ill patient. Articles were selected according to level of evidence with priority given to meta-analyses and randomised controlled trials.

DISCUSSION

Several operational features of CRRT allow this technique to be tolerated more easily in critical illness than IHD. The gradual removal of fluid reduces the incidence of hypotension and the risk of volume overload. Decreased variability in the concentration of solutes enables greater azotemia control. However, CRRT is required to operate uninterrupted to achieve a treatment dose that is equivalent to a conventional IHD treatment schedule. In the absence of definitive evidence to validate superior patient survival and return of renal function there is disagreement as to the most appropriate form of Renal Replacement Therapy (RRT) for the critically ill patient. The introduction of 'hybrid' therapies offers a further alternative treatment strategy, which combine favourable aspects of IHD and CRRT.

CONCLUSION

The decision to use IHD or CRRT should be guided by the therapeutic needs of the patient rather than the operational differences between the two techniques. The resources and expertise available at the organisation are also important in determining the mode best able to manage the critically ill patient at any stage and may change according to the severity of illness. The emergence of hybrid therapies provides a compromise option which encompasses many of the features of both systems, but does not embrace all options of either approach.

Biocompatible hemodialysis membranes for acute renal failure

BACKGROUND

Acute renal failure (ARF) is associated with substantial morbidity and mortality. Some studies have reported a survival advantage among patients dialyzed with biocompatible membranes (BCM) compared to bioincompatible membranes (BICM). These findings were not consistently observed in subsequent studies.

OBJECTIVES

To ascertain whether the use of BCM confers an advantage in either survival or recovery of renal function over the use of BICM in adult patients with ARF requiring intermittent hemodialysis.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, in The Cochrane Library), MEDLINE (from 1966), EMBASE (from 1980), the Mexican Index of Latin American Biomedical Journals IMBIOMED (from 1990), the Latin American and Caribbean Health Sciences Literature Database LILACS (from 1982), and reference lists of articles. Search date: January 2007

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials comparing the use of a BCM with a BICM in patients > 18 years of age with ARF requiring intermittent hemodialysis.

DATA COLLECTION AND ANALYSIS

Two authors extracted the data independently. Cellulose-derived dialysis membranes were classified as BICM, and synthetic dialyzers were considered as BCM. The main outcomes were all-cause mortality and recovery of renal function by type of dialyzer. We further explored these outcomes according to the flux properties (high-flux or low-flux) of each of these dialyzers. A meta-analysis was conducted by combining data using a random-effects model.

MAIN RESULTS

Ten studies were included in the primary analysis of mortality, with a total of 1100 patients. None of the pooled risk ratios (RRs) reached statistical significance. The pooled RR for mortality was 0.93 (95% confidence interval (CI) 0.81 to 1.07). The overall RR for recovery of renal function, which was inclusive of 1038 patients from nine studies, was 1.09 (95% CI 0.90 to 1.31). The pooled RR for mortality by dialyzer flux property was 1.05 (95% CI 0.81 to 1.37). The pooled RR for recovery of renal function by flux property was 1.30 (95% CI 0.83 to 2.02). A meta-analysis of mortality among kidney transplant recipients was not possible, however the analysis of recovery of renal function in this patient population revealed an RR of 1.05 (95% CI 0.87 to 1.26). Results of sensitivity analyses did not differ significantly from the primary analyses.

AUTHORS' CONCLUSIONS

There is no demonstrable clinical advantage to the use of BCM versus BICM in patients with ARF who require intermittent hemodialysis.

[Extracorporeal blood purification in the intensive care units]

Mortality remains high in intensive care patients with renal failure requiring extra corporeal blood purification. This article reviews the recent data that have led to the improvement of the care for such patients. We will discuss the criteria to determine the choice of the technique (intermittent or continuous), of the membrane, of the prescribing dose, and the type of anticoagulation and when to initiate such a treatment.

Epidemiology of renal recovery after acute renal failure

PURPOSE OF REVIEW

Recovery of renal function after acute renal failure is an important clinical determinant of patient morbidity. Herein, the epidemiology of renal recovery after acute renal failure will be described, along with potential predictive factors and interventions.

RECENT FINDINGS

Renal recovery has been variably defined, most often as recovery to independence from renal replacement therapy. A recent consensus definition for acute renal failure has been published and included provisions for defining renal recovery. Renal recovery to renal replacement therapy independence occurs in the majority by hospital discharge and peaks by 90 days. All of older age, female sex, co-morbid illnesses, especially chronic kidney disease, and late initiation of renal replacement therapy or conventional intermittent renal replacement therapy have been coupled with non-recovery. Analysis of the literature suggests several interventions may influence recovery.

SUMMARY

The prognosis is generally good for recovery after acute renal failure. Most patients will be independent of renal replacement therapy by 90 days. Additional research is necessary, however, to understand recovery rates not only to independence from renal replacement therapy, but also to complete and partial recovery. Future studies need to consider the health economic implications for survival and non-recovery. Finally, questions on the role of various interventions require characterization in randomized controlled trials to determine how they may influence renal prognosis.

Adding a dialysis dose to continuous hemofiltration increases survival in patients with acute renal failure

Acute renal failure (ARF) in critically ill patients is associated with high mortality. Optimal method and dose of continuous renal replacement therapy could improve survival in these patients. We studied the hypothesis that an increase in dialysis dose obtained by continuous veno-venous hemodiafiltration (CVVHDF) is associated with a better survival than continuous veno-venous hemofiltration (CVVH) among critically ill patients with ARF. In a prospective randomized trial, these two methods were compared in patients undergoing renal replacement therapy in two intensive care units (ICUs). The patients had either CVVH (1-2.5 l/h replacement fluid) or continuous CVVHDF (1-2.5 l/h replacement fluid+1-1.5 l/h dialysate) according to their body weight. 28- and 90-day mortalities, renal recovery, and duration of ICU stay were the main outcome measures. Two hundred and six patients were randomized from October 2000 to December 2003. Twenty-eight-day survivals (%) were, respectively, 39 and 59 (P=0.03) in the CVVH and CVVHDF groups. Three months survivals (%) were, respectively, 34 and 59 (P=0.0005) in the CVVH and CVVHDF groups. Apache II score, age, baseline blood urea nitrogen, and hemodiafiltration (hazard ratio 0.59, 95% confidence interval 0.40-0.87; P=0.008) were independent predictors of survival at 90 days. Renal recovery rate among survivors (71 versus 78% in the CVVH and CVVHDF groups respectively, P=0.62) was not affected by the type of renal replacement therapy. These results suggest that increasing the dialysis dose especially for low molecular weight solutes confers a better survival in severely ill patients with ARF.