Patient and Kidney Survival by Dialysis Modality in Critically Ill Patients with Acute Kidney Injury

Long-Term Mortality and Health-Related Quality of Life After Continuous Versus Intermittent Renal Replacement Therapy in ICU Survivors: A Secondary Analysis of the Quality of Life After ICU Study

Purpose: We assessed long-term outcomes in intensive care unit (ICU) survivors with acute kidney injury (AKI) submitted to intermittent or continuous renal replacement therapy (RRT) for comparisons between groups. Methods: The multicenter prospective cohort study included 195 adult ICU survivors with an ICU stay >72 h in 10 ICUs that had at least one episode of AKI treated with intermittent RRT (IRRT) or continuous RRT (CRRT) during ICU stay. The main outcomes were mortality and health-related quality of life (HRQoL). Hospital readmissions and physical dependence were also assessed. Results: Regarding RRT, 83 (42.6%) patients received IRRT and 112 (57.4%) received CRRT. Despite the similarity regarding sociodemographic characteristics, pre-ICU state of health and type of admission between groups, the risk of death (23.5% vs 42.7%; P < .001), the prevalence of sepsis (60.7%) and acute respiratory distress syndrome (17%) were higher at ICU admission among CRRT patients. The severity of critical illness was higher among CRRT patients, regarding the need for mechanical ventilation (75.0% vs 50.6%, P = .002) and vasopressors (91.1% vs 63.9%, P < .001). One year after ICU discharge, 67 of 195 ICU survivors died (34.4%) and, after adjustment for confounders, there were no significant differences in mortality when comparing IRRT and CRTT patients (34.9% vs 33.9%; P = .590), on HRQoL in both physical (41.9% vs 42.2%; P = .926) and mental dimensions (57.6% vs 56.6%; P = .340), and on the number of hospital readmissions and physical dependence. Conclusions: Our study suggests that among ICU survivors RRT modality (IRRT vs CRRT) in the ICU does not impact long-term outcomes after ICU discharge.

Epidemiology and Outcomes of AKI Treated With Continuous Kidney Replacement Therapy: The Multicenter CRRTnet Study

Rationale & Objective

Continuous kidney replacement therapy (CKRT) is the predominant form of acute kidney replacement therapy used for critically ill adult patients with acute kidney injury (AKI). Given the variability in CKRT practice, a contemporary understanding of its epidemiology is necessary to improve care delivery.

Study Design

Multicenter, prospective living registry.

Setting & Population

1,106 critically ill adults with AKI requiring CKRT from December 2013 to January 2021 across 5 academic centers and 6 intensive care units. Patients with pre-existing kidney failure and those with coronavirus 2 infection were excluded.

Exposure

CKRT for more than 24 hours.

Outcomes

Hospital mortality, kidney recovery, and health care resource utilization.

Analytical Approach

Data were collected according to preselected timepoints at intensive care unit admission and CKRT initiation and analyzed descriptively.

Results

Patients' characteristics, contributors to AKI, and CKRT indications differed among centers. Mean (standard deviation) age was 59.3 (13.9) years, 39.7% of patients were women, and median [IQR] APACHE-II (acute physiologic assessment and chronic health evaluation) score was 30 [25-34]. Overall, 41.1% of patients survived to hospital discharge. Patients that died were older (mean age 61 vs. 56.8, P < 0.001), had greater comorbidity (median Charlson score 3 [1-4] vs. 2 [1-3], P < 0.001), and higher acuity of illness (median APACHE-II score 30 [25-35] vs. 29 [24-33], P = 0.003). The most common condition predisposing to AKI was sepsis (42.6%), and the most common CKRT indications were oliguria/anuria (56.2%) and fluid overload (53.9%). Standardized mortality ratios were similar among centers.

Limitations

The generalizability of these results to CKRT practices in nonacademic centers or low-and middle-income countries is limited.

Conclusions

In this registry, sepsis was the major contributor to AKI and fluid management was collectively the most common CKRT indication. Significant heterogeneity in patient- and CKRT-specific characteristics was found in current practice. These data highlight the need for establishing benchmarks of CKRT delivery, performance, and patient outcomes. Data from this registry could assist with the design of such studies.

Cost-effectiveness of the TherMax blood warmer during continuous renal replacement therapy

Hypothermia is a common adverse event during continuous renal replacement therapy (CRRT), affecting multiple organ systems and increasing risk of poor health outcomes among patients with acute kidney injury (AKI) undergoing CRRT. TheraMax blood warmers are the next generation of extracorporeal blood warmers which reduce risk of hypothermia during CRRT. The purpose of this study is to elucidate the potential health economic impacts of avoiding CRRT-induced hypothermia by using the novel TherMax blood warming device. This study compares health care costs associated with use of the new TherMax blood warmer unit integrated with the PrisMax system compared to CRRT with a standalone blood warming device to avoid hypothermia in continuous renal replacement therapy (CRRT). An economic model was developed in which relevant health states for each intervention were normothermia, hypothermia, discharge, and death. Clinical inputs and costs were obtained from a combination of retrospective chart review and publicly available summary estimates. The proportion of AKI patients treated with CRRT who became hypothermic (<36°C) during CRRT treatment was 34.5% in the TherMax group compared to 71.9% in the ‘standalone warmer’ group. Given the 78.7-year average life expectancy in the US and the assumed average patient age at discharge/death of 65.4 years, the total life-years gained by avoiding mortality related to hypothermia was 9.0 in the TherMax group compared to 8.0 in the ‘standalone warmer’ group. Cost per life-year gained was $8,615 in the TherMax group versus $10,115 in the ‘standalone warmer’ group for a difference of -$1,501 favoring TherMax. The incremental cost-effectiveness ratio was negative, indicating superior cost-effectiveness for TherMax versus ‘standalone warmer’. The TherMax blood warming device used with the PrisMax system is associated with lower risk of hypothermia, which our model indicates leads to lower costs, lower risk of mortality due to hypothermia, and superior cost-effectiveness.

Acute Kidney Injury at the Neurocritical Care Unit

Neurocritical care has advanced substantially in recent decades, allowing doctors to treat patients with more complicated conditions who require a multidisciplinary approach to achieve better clinical outcomes. In neurocritical patients, nonneurological complications such as acute kidney injury (AKI) are independent predictors of worse clinical outcomes. Different research groups have reported an AKI incidence of 11.6% and an incidence of stage 3 AKI, according to the Kidney Disease: Improving Global Outcomes, that requires dialysis of 3% to 12% in neurocritical patients. These patients tend to be younger, have less comorbidity, and have a different risk profile, given the diagnostic and therapeutic procedures they undergo. Trauma-induced AKI, sepsis, sympathetic overstimulation, tubular epitheliopathy, hyperchloremia, use of nephrotoxic drugs, and renal hypoperfusion are some of the causes of AKI in neurocritical patients. AKI is the result of a sum of events, although the mechanisms underlying many of them remain uncertain; however, two important causes that merit mention are direct alteration of the physiological brain-kidney connection and exposure to injury as a result of the specific medical management and well-established therapies that neurocritical patients are subjected to. This review will focus on AKI in neurocritical care patients. Specifically, it will discuss its epidemiology, causes, associated mechanisms, and relationship to the brain-kidney axis. Additionally, the use and risks of extracorporeal therapies in this group of patients will be reviewed.

Continuous Venovenous Hemofiltration is Associated with Improved Survival in Burn Patients with Shock: A Subset Analysis of a Multicenter Observational Study

INTRODUCTION

Acute kidney injury (AKI) is associated with high mortality in burn patients. Previously, we reported that timely initiation of renal replacement therapy (RRT) with an individualized preference toward continuous modes at relatively higher than recommended doses has become standard practice in critically ill burn patients with AKI and is associated with a historically low mortality. The purpose of this cohort analysis was to determine if modality choice impacted survival in burn patients.

METHODS

After Institutional Review Board approval, a subset analysis was performed on de-identified data collected during a multicenter, observational study. All patients (n = 170) were 18 years or older, admitted with severe burn injuries and started on RRT. Comparisons were made utilizing χ2 or Fisher's exact test. Kaplan-Meier plots were utilized to assess survival. Sample size determinations to aid future research were calculated utilizing χ2 test with a Yates Correction Factor.

RESULTS

Demographics and revised Baux were similar between groups. When continuous venovenous hemofiltration (CVVH) was compared to all other modalities, there was no statistically significant difference in survival (56 vs. 43%, p = 0.124). However, survival was significantly improved (54 vs. 37%, p = 0.032) in the subset of patients requiring vasopressors (n = 77). There was no statistically significant survival difference in patients with inhalation injury (38 vs. 29%, p = 0.638) or acute lung injury/acute respiratory distress syndrome (51 vs. 33%, p = 0.11).

DISCUSSION/CONCLUSION

Survival may be improved if CVVH is chosen as the preferred modality in burn patients with shock and requiring RRT. Differences in other subsets were promising, but analysis was underpowered. Further research should determine if modality choice provides survival benefit in any other subset of burn injury.

Predictors of successful discontinuation from renal replacement therapy during AKI: A meta-analysis

The predictors of weaning time of renal replacement therapy (RRT) remain controversial for special patients suffering from acute kidney injury (AKI). The present work aims to perform a meta-analysis to evaluate proper predictors of RRT weaning in AKI patients. We systematically searched EMBASE, PubMed, and Cochrane Central Register of Controlled trials for literatures between 1984 and June 2019. Studies evaluating predictors of weaning success of RRT in patients of AKI were included. Random-effects model or fixed-effects model meta-analyses were performed to compute a standard mean difference (SMD). Newcastle-Ottawa Scale was employed to assess the risk of bias. We included 10 observational trials including 1453 patients. Twelve predictors including urine output, serum creatinine, serum urea, mean arterial pressure, central venous pressure, lactate, serum potassium, serum bicarbonate, pH value, SOFA score, urinary urea, and urinary creatinine were identified, showing urine output (p = 0.0000), serum creatinine (p = 0.008), serum potassium (p = 0.02), serum bicarbonate (p = 0.01), pH value (p = 0.03), urinary urea (p = 0.002), and urinary creatinine (p = 0.02) were significantly associated with weaning success. With the limited evidence, we speculate that urine output, serum creatinine, serum potassium, serum bicarbonate, pH value, urinary urea, and urinary creatinine might be associated with successful weaning.

Use of matching methods in observational studies with critical patients and renal outcomes. Scoping review

Introduction: The use of matching techniques in observational studies has been increasing and is not always used appropriately. Clinical experiments are not always feasible in critical patients with renal outcomes, and observational studies are an important alternative. Objective: Through a scoping review, determine the available evidence on the use of matching methods in studies involving critically ill patients and assessing renal outcomes. Methods: Medline, Embase, and Cochrane databases were used to identify articles published between 1992 and 2020 up to week 10, which studied different exposures in the critically ill patient with renal outcomes and used propensity matching methods. Results: Most publications are cohort studies 94 (94. 9 %), five studies (5. 1 %) were cross-sectional. The main pharmacological intervention was the use of antibiotics in seven studies (7. 1%) and the main risk factor studied was renal injury prior to ICU admission in 10 studies (10. 1%). The balance between the baseline characteristics assessed by standardized means, in only 28 studies (28. 2%). Most studies 95 (96 %) used logistic regression to calculate the propensity index. Conclusion: Major inconsistencies were observed in the use of methods and in the reporting of findings. A summary is made of the aspects to be considered in the use of the methods and reporting of the findings with the matching by propensity index.

Acute cardiorenal syndrome in acute heart failure: focus on renal replacement therapy

Almost half of hospitalised patients with acute heart failure develop acute cardiorenal syndrome. Treatment consists of optimisation of fluid status and haemodynamics, targeted therapy for the underlying cardiac disease, optimisation of heart failure treatment and preventive measures such as avoidance of nephrotoxic agents. Renal replacement therapy may be temporarily needed to support kidney function, mostly in case of diuretic resistant fluid overload or severe metabolic derangement. The best timing to initiate renal replacement therapy and the best modality in acute heart failure are still under debate. Several modalities are available such as intermittent and continuous renal replacement therapy as well as hybrid techniques, based on two main principles: haemofiltration and haemodialysis. Although continuous techniques have been associated with less haemodynamic instability and a greater chance of renal recovery, cohort data are conflicting and randomised controlled trials have not shown a difference in recovery or mortality. In the presence of diuretic resistance, isolated ultrafiltration with individualisation of ultrafiltration rates is a valid option for decongestion in acute heart failure patients. Practical tools to optimise the use of renal replacement therapy in acute heart failure-related acute cardiorenal syndrome were discussed.

Effect of renal replacement therapy modalities on renal recovery and mortality for acute kidney injury: A PRISMA-compliant systematic review and meta-analysis

Previous investigations showed inconsistent results for comparison in renal recovery, in-hospital, and in-intensive care unit (ICU) mortalities between acute kidney injury (AKI) patients treated with continuous renal replacement therapy (CRRT) and some kinds of intermittent renal replacement therapies (IRRTs). We systematically searched for articles published in the databases (PubMed, Web of Science, EMBASE, Medline, and Google Scholar) until June 2019. We made all statistical analysis using STATA 12.0 software. In the present meta-analysis, relative risks with 95% confidence intervals were calculated for binary outcomes (renal recovery status or mortality). The present study indicated no significant differences in renal recovery, in-hospital mortality, and in-ICU mortality between AKI patients given CRRT and those given sustained low-efficiency dialysis (SLED). Additionally, the study showed no significant difference in in-hospital mortality between AKI patients given CRRT and those given intermittent hemodialysis (IHD), whereas elevated in-ICU mortality was detected in AKI patients given CRRT, compared to those given IHD. The three modalities (CRRT, IHD, and SLED) have their own advantages and disadvantages. More rigorous trials design with large cohort should be made to explore the differences in renal recovery, in-hospital, and in-ICU mortalities between different kinds of RRTs.

The Cost-Effectiveness of Continuous Versus Intermittent Renal Replacement Therapies in Acute Kidney Injury: Perspective of the Social Services for the Elderly in Argentina

BACKGROUND

Acute kidney injury (AKI) is a public health problem that affects millions of hospitalized patients worldwide. In Argentina, evidence suggests that its incidence has risen in recent years. When severe, AKI may require a renal replacement therapy (RRT) where continuous RRT (CRRT) and intermittent RRT (IRRT) are plausible options for patients in the intensive care unit.

OBJECTIVE

To evaluate the cost utility of CRRT versus IRRT for the National Institute of Social Services for Retirees and Pensioners, the largest social security health insurance for elders in Argentina.

METHODS

This was a model-based cost-utility analysis. Long-term costs and health outcomes were estimated for a hypothetical cohort with a Markov model. Parameters used were obtained from published literature and validated with local experts. Local costs were estimated and expressed in $AR of 2016. Several sensitivity analyses were run to analyze the impact of uncertainty on results.

RESULTS

Continuous RRT dominated IRRT by cumulating over the model more quality-adjusted life years and less costs. Total discounted quality-adjusted life years for both cohorts were 1049 and 1034, respectively, and total costs were $95 362 and $103 871. Cost-effectiveness (CE) results reflect these differences in favor of CRRT with a deterministic cost-saving incremental CE ratio and a probability of CRRT being CE of 65.4%, considering a CE threshold of 1 gross domestic product per capita.

CONCLUSIONS

Continuous RRT for patients with AKI eligible for CRRT or IRRT would probably be a cost-effective intervention for the National Institute of Social Services for Retirees and Pensioners' view. Nevertheless, there is considerable uncertainty around results, mainly due to the lack of adequate controlled studies and local data on the prognosis of these patients in Argentina.

Renal Replacement Therapy Modality in the ICU and Renal Recovery at Hospital Discharge

OBJECTIVES

Acute kidney injury requiring renal replacement therapy is a major concern in ICUs. Initial renal replacement therapy modality, continuous renal replacement therapy or intermittent hemodialysis, may impact renal recovery. The aim of this study was to assess the influence of initial renal replacement therapy modality on renal recovery at hospital discharge.

DESIGN

Retrospective cohort study of all ICU stays from January 1, 2010, to December 31, 2013, with a "renal replacement therapy for acute kidney injury" code using the French hospital discharge database.

SETTING

Two hundred ninety-one ICUs in France.

PATIENTS

A total of 1,031,120 stays: 58,635 with renal replacement therapy for acute kidney injury and 25,750 included in the main analysis.

INTERVENTIONS

None.

MEASUREMENTS MAIN RESULTS

PPatients alive at hospital discharge were grouped according to initial modality (continuous renal replacement therapy or intermittent hemodialysis) and included in the main analysis to identify predictors of renal recovery. Renal recovery was defined as greater than 3 days without renal replacement therapy before hospital discharge. The main analysis was a hierarchical logistic regression analysis including patient demographics, comorbidities, and severity variables, as well as center characteristics. Three sensitivity analyses were performed. Overall mortality was 56.1%, and overall renal recovery was 86.2%. Intermittent hemodialysis was associated with a lower likelihood of recovery at hospital discharge; odds ratio, 0.910 (95% CI, 0.834-0.992) p value equals to 0.0327. Results were consistent across all sensitivity analyses with odds/hazards ratios ranging from 0.883 to 0.958.

CONCLUSIONS

In this large retrospective study, intermittent hemodialysis as an initial modality was associated with lower renal recovery at hospital discharge among patients with acute kidney injury, although the difference seems somewhat clinically limited.

CO2 and O2 removal during continuous veno-venous hemofiltration: a pilot study

Background

Carbon dioxide (CO₂) accumulation is a challenging issue in critically ill patients. CO₂ can be eliminated by renal replacement therapy but studies are scarce and clinical relevance is unknown. We prospectively studied CO₂ and O₂ behavior at different sample points of continuous veno-venous hemofiltration (CVVH) and build a model to calculate CO₂ removal bedside.

Methods

In 10 patients receiving standard CVVH under citrate anticoagulation, blood gas analysis was performed at different sample points within the CVVH circuit. Citrate was then replaced by NaCl 0.9% and sampling was repeated. Total CO₂ (tCO₂), CO₂ flow (V̇CO₂) and O₂ flow (V̇O₂) were compared between different sample points. The effect of citrate on transmembrane tCO₂ was evaluated. Wilcoxon matched-pairs signed rank test was performed to evaluate significance of difference between 2 data sets. Friedman test was used when more data sets were compared.

Results

V̇CO₂ in the effluent (26.0 ml/min) correlated significantly with transmembrane V̇CO₂ (24.2 ml/min). This represents 14% of the average expired V̇CO₂ in ventilated patients. Only 1.3 ml/min CO₂ was removed in the de-aeration chamber, suggesting that CO₂ was almost entirely cleared across the membrane filter. tCO₂ values in effluent, before, and after the filter were not statistically different. Transmembrane tCO₂ under citrate or NaCl 0.9% predilution also did not differ significantly. No changes in V̇O₂ were observed throughout the CVVH circuit. Based on recorded data, formulas were constructed that allow bedside evaluation of CVVH-attributable CO₂ removal.

Conclusion

A relevant amount of CO₂ is removed by CVVH and can be quantified by one simple blood gas analysis within the circuit. Future studies should assess the clinical impact of this observation.

Trial registration

The trial was registered at https://clinicaltrials.gov with trial registration number NCT03314363 on October 192,017.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1378-y) contains supplementary material, which is available to authorized users.

The future for diagnostic tests of acute kidney injury in critical care: evidence synthesis, care pathway analysis and research prioritisation

BACKGROUND

Acute kidney injury (AKI) is highly prevalent in hospital inpatient populations, leading to significant mortality and morbidity, reduced quality of life and high short- and long-term health-care costs for the NHS. New diagnostic tests may offer an earlier diagnosis or improved care, but evidence of benefit to patients and of value to the NHS is required before national adoption.

OBJECTIVES

To evaluate the potential for AKI in vitro diagnostic tests to enhance the NHS care of patients admitted to the intensive care unit (ICU) and identify an efficient supporting research strategy.

DATA SOURCES

We searched ClinicalTrials.gov, The Cochrane Library databases, Embase, Health Management Information Consortium, International Clinical Trials Registry Platform, MEDLINE, metaRegister of Current Controlled Trials, PubMed and Web of Science databases from their inception dates until September 2014 (review 1), November 2015 (review 2) and July 2015 (economic model). Details of databases used for each review and coverage dates are listed in the main report.

REVIEW METHODS

The AKI-Diagnostics project included horizon scanning, systematic reviewing, meta-analysis of sensitivity and specificity, appraisal of analytical validity, care pathway analysis, model-based lifetime economic evaluation from a UK NHS perspective and value of information (VOI) analysis.

RESULTS

The horizon-scanning search identified 152 potential tests and biomarkers. Three tests, Nephrocheck^® (Astute Medical, Inc., San Diego, CA, USA), NGAL and cystatin C, were subjected to detailed review. The meta-analysis was limited by variable reporting standards, study quality and heterogeneity, but sensitivity was between 0.54 and 0.92 and specificity was between 0.49 and 0.95 depending on the test. A bespoke critical appraisal framework demonstrated that analytical validity was also poorly reported in many instances. In the economic model the incremental cost-effectiveness ratios ranged from £11,476 to £19,324 per quality-adjusted life-year (QALY), with a probability of cost-effectiveness between 48% and 54% when tests were compared with current standard care.

LIMITATIONS

The major limitation in the evidence on tests was the heterogeneity between studies in the definitions of AKI and the timing of testing.

CONCLUSIONS

Diagnostic tests for AKI in the ICU offer the potential to improve patient care and add value to the NHS, but cost-effectiveness remains highly uncertain. Further research should focus on the mechanisms by which a new test might change current care processes in the ICU and the subsequent cost and QALY implications. The VOI analysis suggested that further observational research to better define the prevalence of AKI developing in the ICU would be worthwhile. A formal randomised controlled trial of biomarker use linked to a standardised AKI care pathway is necessary to provide definitive evidence on whether or not adoption of tests by the NHS would be of value.

STUDY REGISTRATION

The systematic review within this study is registered as PROSPERO CRD42014013919.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Near-infrared spectroscopy parameters in patients undergoing continuous venovenous hemodiafiltration

OBJECTIVE

To investigate the impacts of continuous venovenous hemodiafiltration on the microcirculation in patients with acute kidney injury.

METHODS

A prospective observational pilot study conducted in a 40-bed, open clinical-surgical intensive care unit of a private tertiary care hospital located in the city of São Paulo (SP), Brazil. Microcirculation was assessed using near-infrared spectroscopy by means of a 15mm probe placed over the thenar eminence. Vascular occlusion test was performed on the forearm to be submitted to near-infrared spectroscopy by inflation of a sphygmomanometer cuff to 30mmHg higher than the systolic arterial pressure. The primary endpoint was the assessment of near-infrared spectroscopy-derived parameters immediately before, 1, 4 and 24 hours after the initiation of continuous venovenous hemodiafiltration.

RESULTS

Nine patients were included in this pilot study over a period of 2 months. Minimum tissue oxygen saturation measured during the vascular occlusion test was the only near-infrared spectroscopy-derived parameter to differed over the time (decrease compared to baseline values up to 24 hours after initiation of continuous venovenous hemodiafiltration).

CONCLUSION

The impacts of microcirculatory dysfunction on clinical outcomes of patients undergoing to continuous venovenous hemodiafiltration need to be further investigated.

[Epidemiology of acute renal failure]

The acute renal failure is common in the hospitalized patients with the incidence is increasing. This results from the aging of the population and the widespread use of nephrotoxic therapies or diagnostic techniques. The acute renal failure is associated with an increased length of stay in hospital and the short and long-term mortality. The most common histological injury is the acute tubular necrosis. Although the most of acute renal failure is recovering, recent works have shown that there is a strong association between an acute renal failure and the increased risk of developing a chronic kidney disease.

Volume Management by Renal Replacement Therapy in Acute Kidney Injury

Management of fluid balance is one of the basic but vital tasks in the care of critically ill patients. Hypovolemia results in a decrease in cardiac output and tissue perfusion and may lead to progressive multiple organ dysfunction, including the development of acute renal injury (AKI). However, in an effort to reverse pre-renal oliguria, it is not uncommon for patients with established oliguric acute renal failure, particularly when associated with sepsis, to receive excessive fluid resuscitation, leading to fluid overload. In patients with established oliguria, renal replacement therapy may be required to treat hypervolemia. Safe prescription of fluid loss during RRT requires intimate knowledge of the patient's underlying condition, understanding of the process of ultrafiltration and close monitoring of the patient's cardiovascular response to fluid removal. To preserve tissue perfusion in patients with AKI, it is important that RRT be prescribed in a way that optimizes fluid balance by removing fluid without compromising the effective circulating fluid volume. In patients who are clinically fluid overloaded, it is equally important that the amount of fluid removed be as exact as possible. Fluid balance errors can occur as a result of inappropriate prescription, operator error or machine error. Some CRRT machines have potential for significant fluid errors if alarms can be overridden. Threshold values for fluid balance error have been developed which can be used to predict the severity of harm. It is important that RRT education programs emphasize the risk associated with fluid balance errors and with overriding machine alarms.

Management of Fluid Balance in Continuous Renal Replacement Therapy: Technical Evaluation in the Pediatric Setting

Fluid overload control and fluid balance management represent very important factors in critically ill children requiring renal replacement therapy A relatively high fluid volume administration in children and neonates is often necessary to deliver adequate amounts of blood derivatives, vasopressors, antibiotics, and parenteral nutrition. Fluid balance errors during pediatric continuous renal replacement therapy (CRRT) might significantly impact therapy delivery and have been described as potentially lethal. The aim of this study was to evaluate the accuracy of delivered vs. prescribed net ultrafiltration (UF) during CRRT applied to 2 neonates and 2 small children, either as dialytic treatment alone or during extracorporeal membrane oxygenation (ECMO). In accordance with an Acute Dialysis Quality Initiative workgroup statement, net UF was defined as the “overall amount of fluid extracted from the patient in a given time”. Mean prescribed net UF was 18.5 ml/h (SD=6.7) during neonatal treatments and 70.3 ml/h (SD=22.5) during CRRT in small children. Daily net UF ranged from 200 mL to about 600 mL in the 2 neonates and from 1,200 to 1800 mL in the 2 children. The percentage error of delivered net UF ranged from −1.6% to 5.8% of the prescribed level. The mean error of the ECMO/CRRT patients was 3.024 ml/h vs. 0.45 m/h for the CRRT patients (p<0.001). The same difference was not evident when the 2 neonates were compared with the 2 small children (without considering the presence of ECMO). CRRT and net UF delivery appeared to be accurate, safe, and effective in this small cohort of high-risk pediatric patients.

Acute Kidney Injury (AKI)

Kidneys perform a multitude of essential functions within the human body. Of these the most important are (1) maintaining pH through regulation of acid/base levels and (2) excreting end products of metabolism. As for most organ-systems, these functions are especially important for healing following trauma and/or surgery and decline with age. Acute Kidney Injury (AKI) is one of the common forms of organ failures seen in the ICU and elderly patients are more prone to it. The causes maybe classified as Prerenal (inadequate perfusion), renal (inherent kidney disease) and post-renal (urinary obstruction). Preventing AKI should be an important concern in all critically ill patients but especially important in the elderly patients since the development of AKI can significantly increase in-hospital mortality. Once AKI has set in a systematic and step-wise approach of diagnosis and management is key to avoiding adverse outcomes.

Experimental and Clinical Evaluation of Predilution and Postdilution Continuous Venovenous Hemofiltration on Clearance Characteristics

We compared the clearance characteristics of low-to-high molecular weight substances during pre-and postdilution continuous venovenous hemofiltration (CVVH) in experimental and clinical conditions. Experimental circuits for pre- and postdilution CVVH were prepared using a test solution containing creatinine (110 Da), inulin (5,000 Da), interleukin (IL)-8 (8,000 Da), IL-6 (22,000 Da), and tumor necrosis factor (TNF)-α (51,000 Da). Quantity of test solution flow and filtration flow (QF) were set to 150 ml/min and 10, 20, and 35 ml/min, respectively. Clinical CVVH settings were blood flow (QB): 150 ml/min and QF: 35 ml/min. Samples were obtained from pre- and posthemofilters, and clearance of target substances was determined during pre- and postdilution CVVH in experimental and clinical conditions. Clearance changed according to QF during both pre- and postdilution CVVH in the experiment. Clearance of creatinine, inulin (experiment only), and IL-8 during postdilution CVVH was superior to that during predilution CVVH. Few differences were seen in clearance of IL-6 and TNF-α between dilution methods in the experiment and clinical practice. Clearance of IL-8 and IL-6 decreased during postdilution CVVH over 24 hr but did not change during predilution CVVH in clinical practice. Predilution CVVH is useful for stable cytokine clearance in septic patients with acute kidney injury.

Intradialytic hypotension in acute kidney injury requiring renal replacement therapy

The treatment of severe acute kidney injury (AKI) with dialytic support for renal replacement therapy can be life sustaining and permit recovery from critical illness. Like any interventional therapy, however, renal replacement therapy with intermittent hemodialysis or continuous therapy can cause complications. Intradialytic hypotension is a common complication and can cause further ischemic injury to the recovering kidneys, thereby reducing the probability of renal recovery. The optimal dialytic technique-continuous or intermittent-has not been conclusively demonstrated in randomized controlled trials. In general, treatment or prophylactic strategies for intradialytic hypotension in AKI have not been comprehensively tested. Given the frequency of intradialytic hypotension in dialytic treatment of AKI and its adverse clinical consequences, future research should rigorously compare dialytic techniques and other prevention strategies in adequately powered, randomized controlled trials.

Systematic review and meta-analysis of renal replacement therapy modalities for acute kidney injury in the intensive care unit

PURPOSE

To compare clinical outcomes among critically ill adults with acute kidney injury (AKI) treated with continuous renal replacement therapy (CRRT), intermittent hemodialysis (IHD) or sustained low efficiency dialysis (SLED).

MATERIALS AND METHODS

We completed a systematic review and meta-analysis of studies published in 2015 or earlier using MEDLINE®, EMBASE®, Cochrane databases and grey literature. Eligible studies included randomized clinical trials (RCTs) or prospective cohort studies comparing outcomes of mortality, dialysis dependence or length of stay among critically ill adults receiving CRRT, IHD or SLED to treat AKI. Mortality and dialysis dependence from RCTs were pooled using meta-analytic techniques. Length of stay from RCTs and results from prospective cohort studies were described qualitatively.

RESULTS

Twenty-one studies were eligible. RRT modality was not associated with in-hospital mortality (CRRT vs IHD: RR 1.00 [95% CI, 0.92-1.09], CRRT vs SLED: RR 1.23 [95% CI, 1.00-1.51]) or dialysis dependence (CRRT vs IHD: RR 0.90 [95% CI, 0.59-1.38], CRRT vs SLED: RR 1.15 [95% CI, 0.67-1.99]).

CONCLUSIONS

We did not find a definitive advantage for any RRT modality on short-term patient or kidney survival. Well-designed, adequately-powered trials are needed to better define the role of RRT modalities for treatment of critically ill patients with AKI.

Sodium modelling to reduce intradialytic hypotension during haemodialysis for acute kidney injury in the intensive care unit

AIM

Intradialytic hypotension often complicates haemodialysis for patients with acute kidney injury (AKI) and may impact renal recovery. Sodium modelling is sometimes used as prophylaxis against intradialytic hypotension in the chronic haemodialysis population, but there is little evidence for its use among critically ill patients with AKI.

METHODS

A retrospective cohort with AKI requiring intermittent haemodialysis in the intensive care unit from 2001 to 2008 was used to study the association of prophylactic sodium modelling and multiple outcomes. Outcomes included a composite of in-hospital death or dialysis dependence at hospital discharge, as well as intradialytic hypotension, ultrafiltration goal achievement and net ultrafiltration volume. Associations were estimated using logistic regression, mixed linear models and generalized estimating equations adjusting for demographic and clinical characteristics.

RESULTS

One hundred and ninety-one individuals who underwent 892 sessions were identified; sodium modelling was prescribed in 27.1% of the sessions. In adjusted analyses, sodium modelling was not significantly associated with intradialytic hypotension (P = 0.67) or with the ultrafiltration goal achievement (P = 0.06). Sodium modelling during the first dialysis session was numerically associated with lower risk for the composite of in-hospital death or dialysis dependence: adjusted odds ratio (95% confidence interval) 0.39 (0.15-1.02; P = 0.06); however, this association did not reach statistical significance.

CONCLUSION

We did not observe statistically significant associations between sodium modelling and improved outcomes among AKI patients receiving intermittent dialysis in the intensive care unit. However, suggestive findings warrant further study.

Effects of continuous and intermittent renal replacement therapies among adult patients with acute kidney injury

Background: Dialysis-dependent acute kidney injury (AKI) can be treated using continuous (CRRT) or intermittent renal replacement therapies (IRRT). Although some studies suggest that CRRT may have advantages over IRRT, study findings are inconsistent. This study assessed differences between CRRT and IRRT regarding important clinical outcomes (such as mortality and renal recovery) and cost-effectiveness. Additionally, ethical aspects that are linked to renal replacement therapies in the intensive care setting are considered.

Methods: Systematic searches in MEDLINE, EMBASE, and Cochrane Library including RCTs, observational studies, and cost-effectiveness studies were performed. Results were pooled using a random effects-model.

Results: Forty-nine studies were included. Findings show a higher rate of renal recovery among survivors who initially received CRRT as compared with IRRT. This advantage applies to the analysis of all studies with different observation periods (Relative Risk (RR) 1.10; 95% Confidence Interval (CI) [1.05, 1.16]) and to a selection of studies with observation periods of 90 days (RR 1.07; 95% CI [1.04, 1.09]). Regarding observation periods beyond there are no differences when only two identified studies were analyzed. Patients initially receiving CRRT have higher mortality as compared to IRRT (RR 1.17; 95% CI [1.06, 1.28]). This difference is attributable to observational studies and may have been caused by allocation bias since seriously ill patients more often initially receive CRRT instead of IRRT. CRRT do not significantly differ from IRRT with respect to change of mean arterial pressure, hypotensive episodes, hemodynamic instability, and length of stay. Data on cost-effectiveness is inconsistent. Recent analyzes indicate that initial CRRT is cost-effective compared to initial IRRT due to a reduction of the rate of long-term dialysis dependence. As regards a short time horizon, this cost benefit has not been shown.

Conclusion: Findings of the conducted assessment show that initial CRRT is associated with higher rates of renal recovery. Potential long-term effects on clinical outcomes for more than three months could not be analyzed and should be investigated in further studies. Economical analyzes indicate that initial CRRT is cost-effective when costs of long-term dialysis dependence are considered. However, transferability of the economic analyzes to the German health care system is limited and the conduction of economical analyzes using national cost data should be considered.

Effects of continuous renal replacement therapy on serum cytokines, neutrophil gelatinase-associated lipocalin, and prognosis in patients with severe acute kidney injury after cardiac surgery

The aim of our study was to evaluate the effect of continuous renal replacement therapy (CRRT) on serum cytokines, neutrophil gelatinase-associated lipocalin (NGAL), and prognosis in patients with severe acute kidney injury (AKI) following cardiac surgery. A total number of 153 patients with severe AKI following cardiac surgery were treated with CRRT. They were divided into the survival and non-survival groups. Clinical data from these two groups before and after CRRT were recorded and analyzed. It was found that the number of impaired organs, MODS and APACHE II scores were significantly higher in the non-survival group than those in the survival group before CRRT. After CRRT, MODS and APACHE II scores decreased significantly. The post-CRRT levels of serum TNF-a and IL-6 were significantly decreased. After CRRT, serum NGAL decreased in the two groups, but the levels were higher in the non-survival group than those in the survival group. MODS and APACHE II scores could be used to evaluate the severity of AKI in patients after cardiac surgery. CRRT is an effective treatment for these patients and high levels of TNF-a, IL-6, and NGAL are associated with a poor prognosis in these patients.

Volume-related weight gain as an independent indication for renal replacement therapy in the intensive care units

Attempts to identify specific therapies to reverse acute kidney injury (AKI) have been unsuccessful in the past; only modifying risk profile or addressing the underlying disease processes leading to AKI proved efficacious. The current thinking on recognizing AKI is compromised by a "kidney function percent-centered" viewpoint, a paradigm further reinforced by the emergence of serum creatinine-based automated glomerular filtration reporting over the last two decades. Such thinking is, however, grossly corrupted for AKI and poorly applicable in critically ill patients in general. Conventional indications for renal replacement therapy (RRT) may have limited applicability in critically ill patients and there has been a relative lack of progress on RRT modalities in these patients. AKI in critically ill patients is a highly complex syndrome and it may be counterproductive to produce complex clinical practice guidelines, which are labor and resource-intensive to maintain, difficult to memorize or may not be immediately available in all settings all over the world. Additionally, despite attempts to develop reliable and reproducible biomarkers to replace serum creatinine as a guide to therapy such biomarkers failed to materialize. Under such circumstances, there is an ongoing need to reassess the practical value of simple measures, such as volume-related weight gain (VRWG) and urine output, both for prognostic markers and clinical indicators for the need for RRT. This current paper reviews the practical utility of VRWG as an independent indication for RRT in face of reduced urine output and hemodynamic instability.

Long-term outcome in ICU patients with acute kidney injury treated with renal replacement therapy: a prospective cohort study

Background

In intensive care unit (ICU) patients, acute kidney injury treated with renal replacement therapy (AKI-RRT) is associated with adverse outcomes. The aim of this study was to evaluate variables associated with long-term survival and kidney outcome and to assess the composite endpoint major adverse kidney events (MAKE; defined as death, incomplete kidney recovery, or development of end-stage renal disease treated with RRT) in a cohort of ICU patients with AKI-RRT.

Methods

We conducted a single-center, prospective observational study in a 50-bed ICU tertiary care hospital. During the study period from August 2004 through December 2012, all consecutive adult patients with AKI-RRT were included. Data were prospectively recorded during the patients’ hospital stay and were retrieved from the hospital databases. Data on long-term follow-up were gathered during follow-up consultation or, in the absence of this, by consulting the general physician.

Results

AKI-RRT was reported in 1292 of 23,665 first ICU admissions (5.5 %). Mortality increased from 59.7 % at hospital discharge to 72.1 % at 3 years. A Cox proportional hazards model demonstrated an association of increasing age, severity of illness, and continuous RRT with long-term mortality. Among hospital survivors with reference creatinine measurements, 1-year renal recovery was complete in 48.4 % and incomplete in 32.6 %. Dialysis dependence was reported in 19.0 % and was associated with age, diabetes, chronic kidney disease (CKD), and oliguria at the time of initiation of RRT. MAKE increased from 83.1 % at hospital discharge to 93.7 % at 3 years. Multivariate regression analysis showed no association of classical determinants of outcome (preexisting CKD, timing of initiation of RRT, and RRT modality) with MAKE at 1 year.

Conclusions

Our study demonstrates poor long-term survival after AKI-RRT that was determined mainly by severity of illness and RRT modality at initiation of RRT. Renal recovery is limited, especially in patients with acute-on-chronic kidney disease, making nephrological follow-up imperative. MAKE is associated mainly with variables determining mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1409-z) contains supplementary material, which is available to authorized users.

Pharmacokinetics and Pharmacodynamics of Extended Infusion Versus Short Infusion Piperacillin-Tazobactam in Critically Ill Patients Undergoing CRRT

BACKGROUND AND OBJECTIVES

Infection is the most common cause of death in severe AKI, but many patients receiving continuous RRT do not reach target antibiotic concentrations in plasma. Extended infusion of β-lactams is associated with improved target attainment in critically ill patients; thus, we hypothesized that extended infusion piperacillin-tazobactam would improve piperacillin target attainment compared with short infusion in patients receiving continuous RRT.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted an institutional review board-approved observational cohort study of piperacillin-tazobactam pharmacokinetics and pharmacodynamics in critically ill patients receiving continuous venovenous hemodialysis and hemodiafiltration at three tertiary care hospitals between 2007 and 2015. Antibiotic concentrations in blood and/or dialysate samples were measured by liquid chromatography, and one- and two-compartment pharmacokinetic models were fitted to the data using nonlinear mixed effects regression. Target attainment for piperacillin was defined as achieving four times the minimum inhibitory concentration of 16 μg/ml for >50% of the dosing cycle. The probabilities of target attainment for a range of doses, frequencies, and infusion durations were estimated using a Monte Carlo simulation method. Target attainment was also examined as a function of patient weight and continuous RRT effluent rate.

RESULTS

Sixty-eight participants had data for analysis. Regardless of infusion duration, 6 g/d piperacillin was associated with ≤45% target attainment, whereas 12 g/d was associated with ≥95% target attainment. For 8 and 9 g/d, target attainment ranged between 68% and 85%. The probability of target attainment was lower at higher effluent rates and patient weights. For all doses, frequencies, patient weights, and continuous RRT effluent rates, extended infusion was associated with higher probability of target attainment compared with short infusion.

CONCLUSIONS

Extended infusions of piperacillin-tazobactam are associated with greater probability of target attainment in patients receiving continuous RRT.

Fluid overload in the ICU: evaluation and management

BACKGROUND

Fluid overload is frequently found in acute kidney injury patients in critical care units. Recent studies have shown the relationship of fluid overload with adverse outcomes; hence, manage and optimization of fluid balance becomes a central component of the management of critically ill patients.

DISCUSSION

In critically ill patients, in order to restore cardiac output, systemic blood pressure and renal perfusion an adequate fluid resuscitation is essential. Achieving an appropriate level of volume management requires knowledge of the underlying pathophysiology, evaluation of volume status, and selection of appropriate solution for volume repletion, and maintenance and modulation of the tissue perfusion. Numerous recent studies have established a correlation between fluid overload and mortality in critically ill patients. Fluid overload recognition and assessment requires an accurate documentation of intakes and outputs; yet, there is a wide difference in how it is evaluated, reviewed and utilized. Accurate volume status evaluation is essential for appropriate therapy since errors of volume evaluation can result in either in lack of essential treatment or unnecessary fluid administration, and both scenarios are associated with increased mortality. There are several methods to evaluate fluid status; however, most of the tests currently used are fairly inaccurate. Diuretics, especially loop diuretics, remain a valid therapeutic alternative. Fluid overload refractory to medical therapy requires the application of extracorporeal therapies. In critically ill patients, fluid overload is related to increased mortality and also lead to several complications like pulmonary edema, cardiac failure, delayed wound healing, tissue breakdown, and impaired bowel function. Therefore, the evaluation of volume status is crucial in the early management of critically ill patients. Diuretics are frequently used as an initial therapy; however, due to their limited effectiveness the use of continuous renal replacement techniques are often required for fluid overload treatment. Successful fluid overload treatment depends on precise assessment of individual volume status, understanding the principles of fluid management with ultrafiltration, and clear treatment goals.

Daily urinary creatinine predicts the weaning of renal replacement therapy in ICU acute kidney injury patients

Background

In acute kidney injury (AKI), useless continuation of renal replacement therapy (RRT) may delay renal recovery and impair patient’s outcome. In this study, we aimed to identify predictive parameters that may help to a successful RRT weaning for AKI patients.

Methods

We studied 54 surviving AKI patients in which a weaning of RRT was attempted. On the day of weaning (D₀) and the following 2 days (D₁ and D₂), SAPS II and SOFA scores, 24-h diuresis, 24-h urinary creatinine and urea (UCr and UUr), creatinine and urea generation rates (CrGR and UrGR) and clearances (CrCl and UrCl) were collected. Patients who remained free of RRT 15 days after its discontinuation were considered as successfully weaned.

Results

Twenty-six RRT weaning attempts succeeded (S₊) and 28 failed (S₋). Age, previous renal function, SAPS II and SOFA scores were comparable between groups. At D₀, 24-h diuresis was 2300 versus 1950 ml in S₊ and S_−, respectively, p = 0.05. At D₀, D₁ and D₂, 24-h UUr and UCr levels, UrCl and CrCl, and UUr/UrGR and UCr/CrGR ratios were significantly higher in S₊ group. By multivariate analysis, D₁ 24-h UCr was the most powerful parameter that was associated with RRT weaning success with an area under the ROC curve of 0.86 [0.75–0.97] and an odds ratio of 2.01 [1.27–3.18], p = 0.003.

Conclusions

In ICU AKI, 24-h UCr appeared as an efficient and independent marker of a successful weaning of RRT. A 24-h UCr ≥5.2 mmol was associated with a successful weaning in 84 % of patients.

Modality of RRT and Recovery of Kidney Function after AKI in Patients Surviving to Hospital Discharge

BACKGROUND AND OBJECTIVES

Observational evidence has suggested that RRT modality may affect recovery after AKI. It is unclear whether initial choice of intermittent hemodialysis or continuous RRT affects renal recovery, survival, or development of ESRD in critically ill patients when modality choice is made primarily on hemodynamics.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a retrospective cohort study examining adults (≥18 years old) admitted to intensive care units from 2000 to 2008 who received RRT for AKI and survived to hospital discharge or 90 days. We analyzed renal recovery (alive and not requiring RRT) and reasons for nonrecovery (death or ESRD) at 90 and 365 days. Conditional multivariable logistic regression was used to assess differences in renal recovery at 90 and 365 days between continuous RRT and intermittent hemodialysis. Models were stratified by propensity for continuous RRT and adjusted for age and reference creatinine.

RESULTS

Of 4738 patients with Kidney Disease Improving Global Outcomes stage 3 AKI, 1338 (28.2%) received RRT, and 638 (47.7%) survived to hospital discharge (353 intermittent hemodialysis and 285 continuous RRT). Recovery from AKI was lower for intermittent hemodialysis versus continuous RRT at 90 days (66.6% intermittent hemodialysis versus 75.4% continuous RRT; P=0.02) but similar at 365 days (54.1% intermittent hemodialysis versus 59.6% continuous RRT; P=0.17). In multivariable analysis, there was no difference in odds of recovery at 90 or 365 days for patients initially treated with continuous RRT versus intermittent hemodialysis (90 days: odds ratio, 1.19; 95% confidence interval, 0.91 to 1.55; P=0.20; 365 days: odds ratio, 0.93; 95% confidence interval, 0.72 to 1.2; P=0.55).

CONCLUSIONS

We found no significant difference in hazards for nonrecovery or reasons for nonrecovery (mortality or ESRD) with intermittent hemodialysis versus continuous RRT. These results suggest that, when initial RRT modality is chosen primarily on hemodynamics, renal recovery and clinical outcomes in survivors are similar between intermittent hemodialysis and continuous RRT.

Hospital Admission following Acute Kidney Injury in Kidney Transplant Recipients Is Associated with a Negative Impact on Graft Function after 1-Year

The incidence and outcomes of acute kidney injury (AKI) in kidney transplantation are poorly known. Retrospective cohort analysis was performed on the data of all patients (≥3 months after transplantation and ≥16 years of age) admitted to the hospital due to medical or surgical complications from 2007 to 2010. We analyzed 458 kidney transplant recipients, 55.2% men, median age 49 (IQR, 36-58) years, median of 12.5 (IQR, 3-35) months after kidney transplantation; admitted to the hospital due to medical or surgical complications. Most of the patients received a kidney from a deceased donor (62.2%), the primary cause for hospital admission was infection (60.7%) and 57 (12.4%) individuals were diagnosed with acute rejection (AR). The incidence of AKI was 82.3%: 31.9% stage 1, 29.3% stage 2 and 21.2% stage 3. Intensive care unit (ICU) admission (OR 8.90, 95% CI: 1.77-44.56 p = 0.008), infection (OR 5.73, 95% CI: 2.61-12.56, p<0.001) and the use of contrast media (OR 9.34, 95% CI: 2.04-42.70, p = 0.004) were the independent risk factors for AKI development. The mortality rate was 2.1% and all patients who died were diagnosed with AKI. Even after the exclusion of AR cases, at the end of 12 months, the individuals with AKI exhibited higher percent changes in creatinine values when compared with individuals without AKI (9.1% vs. -4.3%; p<0.001). According to KDIGO system, we found a high incidence of AKI among the complications of renal transplantation. As in other scenarios, AKI was associated with renal function loss at 1-year after the hospital discharge.

Promoting Kidney Function Recovery in Patients with AKI Requiring RRT

AKI requiring RRT is associated with high mortality, morbidity, and long-term consequences, including CKD and ESRD. Many patients never recover kidney function; in others, kidney function improves over a period of many weeks or months. Methodologic constraints of the available literature limit our understanding of the recovery process and hamper adequate intervention. Current management strategies have focused on acute care and short-term mortality, but new data indicate that long-term consequences of AKI requiring RRT are substantial. Promotion of kidney function recovery is a neglected focus of research and intervention. This lack of emphasis on recovery is illustrated by the relative paucity of research in this area and by the lack of demonstrated effective management strategies. In this article the epidemiologic implications of kidney recovery after AKI requiring RRT are discussed, the available literature and its methodologic constraints are reviewed, and strategies to improve the understanding of factors that affect kidney function recovery are proposed. Measures to promote kidney function recovery are a serious unmet need, with a great potential to improve short- and long-term patient outcomes.

[Acute kidney injury: choice of the initial modality for renal replacement therapy]

Continuous and intermittent renal replacement therapies are thought to be equally adequate approaches for the treatment of patients with acute kidney injury. Accordingly, current guidelines advocate the use of different modalities in a complementary fashion, i.e., to tailor therapy to the specific clinical situation. In patients with hemodynamic instability or at risk of cerebral edema, continuous renal replacement therapy or prolonged intermittent renal replacement therapy should, however, be preferred. Intermittent hemodialysis, on the other hand, remains the therapy of choice for the rapid correction of life-threatening electrolyte abnormalities or metabolic acidosis. During the further course of treatment, an individualized approach should be continued which may include a switch between modalities based on current therapeutic goals and potential risks for side effects of renal replacement therapy.

Current state of continuous renal replacement therapy for acute kidney injury in Japanese intensive care units in 2011: analysis of a national administrative database

BACKGROUND

Nationwide data for the prevalence and outcomes of patients receiving continuous renal replacement therapy (CRRT) in intensive care units (ICUs) are scarce. This study assessed the status of CRRT in Japanese ICUs using a nationwide administrative claim database.

METHODS

Data were extracted from the Japanese Diagnosis Procedure Combination database for 2011. From a cohort of critically ill patients aged 12 years or older who were admitted to ICUs for 3 days or longer, acute kidney injury (AKI) patients treated with CRRT were identified. The period prevalence of CRRT and in-hospital mortality were calculated. Logistic regression analysis identified factors associated with in-hospital mortality.

RESULTS

Of 165 815 ICU patients, 6478 (3.9%) received CRRT for AKI. The most frequent admission diagnosis category was diseases of the circulatory system (n = 3074). The overall in-hospital mortality rate of the CRRT-treated AKI patients was 50.6%. Clustering patients into four groups by background revealed the lowest in-hospital mortality rate of 41.5% for the cardiovascular surgery group (n = 1043) compared with 53.5% for the nonsurgical cardiovascular group (n = 2031), 51.7% for the sepsis group (n = 1863) and 51.6% for other cases (n = 1541). Multiple logistic regression analysis showed a significant association of these four group classifications with in-hospital mortality in addition to age, hospital characteristics (type and volume), time from hospital admission to CRRT initiation and interventions performed on the day of CRRT initiation.

CONCLUSIONS

Using a large Japanese nationwide database, this study revealed remarkably high in-hospital mortality of CRRT-treated AKI patients, although the period prevalence of CRRT for AKI in ICUs was low.

Acute kidney injury in 2014: a step towards understanding mechanisms of renal repair

In 2014, key articles in the field of acute kidney injury highlighted the importance of tubular homeostasis in renal regeneration. Cell cycle regulators, inflammatory signals and progenitors were identified as important factors that mediate the balance between inflammation and tubular regeneration necessary for renal repair.

Economics of dialysis dependence following renal replacement therapy for critically ill acute kidney injury patients

BACKGROUND

The obective of this study was to perform a cost-effectiveness analysis comparing intermittent with continuous renal replacement therapy (IRRT versus CRRT) as initial therapy for acute kidney injury (AKI) in the intensive care unit (ICU).

METHODS

Assuming some patients would potentially be eligible for either modality, we modeled life year gained, the quality-adjusted life years (QALYs) and healthcare costs for a cohort of 1000 IRRT patients and a cohort of 1000 CRRT patients. We used a 1-year, 5-year and a lifetime horizon. A Markov model with two health states for AKI survivors was designed: dialysis dependence and dialysis independence. We applied Weibull regression from published estimates to fit survival curves for CRRT and IRRT patients and to fit the proportion of dialysis dependence among CRRT and IRRT survivors. We then applied a risk ratio reported in a large retrospective cohort study to the fitted CRRT estimates in order to determine the proportion of dialysis dependence for IRRT survivors. We conducted sensitivity analyses based on a range of differences for daily implementation cost between CRRT and IRRT (base case: CRRT day $632 more expensive than IRRT day; range from $200 to $1000) and a range of risk ratios for dialysis dependence for CRRT as compared with IRRT (from 0.65 to 0.95; base case: 0.80).

RESULTS

Continuous renal replacement therapy was associated with a marginally greater gain in QALY as compared with IRRT (1.093 versus 1.078). Despite higher upfront costs for CRRT in the ICU ($4046 for CRRT versus $1423 for IRRT in average), the 5-year total cost including the cost of dialysis dependence was lower for CRRT ($37 780 for CRRT versus $39 448 for IRRT on average). The base case incremental cost-effectiveness analysis showed that CRRT dominated IRRT. This dominance was confirmed by extensive sensitivity analysis.

CONCLUSIONS

Initial CRRT is cost-effective compared with initial IRRT by reducing the rate of long-term dialysis dependence among critically ill AKI survivors.

Choice of renal replacement therapy modality in intensive care units: data from a Japanese Nationwide Administrative Claim Database

PURPOSE

This study was undertaken to assess recent trends of the choice of renal replacement therapy (RRT) modalities in Japanese intensive care units (ICUs).

MATERIALS AND METHODS

Data were extracted from the Japanese Diagnosis Procedure Combination database for 2011. We identified adult patients without end-stage renal disease who had been admitted to ICUs for 3 days or longer and started continuous RRT (CRRT) or intermittent RRT (IRRT). Logistic regression was used to analyze which factors affected the modality choice. We further evaluated in-hospital mortality according to the choice of RRT.

RESULTS

Of 7353 eligible patients, 5854 (79.6%) initially received CRRT. The choice of CRRT was independently associated with sex (female), diagnosis of sepsis, hospital type (academic) and volume, vasoactive agents, mechanical ventilation, colloid administration, blood transfusion, intra-aortic balloon pumping, and venoarterial extracorporeal membrane oxygenation. Particularly, the number of vasoactive drugs was strongly associated with the CRRT choice. Overall in-hospital mortality in the CRRT group was higher than that in the IRRT group (50.0% vs 31.1%) and was increased when IRRT was switched to CRRT (59.1%).

CONCLUSIONS

Continuous RRT is apparently preferred in actual ICU practice, especially for hemodynamically unstable patients, and subsequent RRT modality switch is associated with mortality.

The Japanese guidelines for the management of sepsis

This is a guideline for the management of sepsis, developed by the Sepsis Registry Committee of The Japanese Society of Intensive Care Medicine (JSICM) launched in March 2007. This guideline was developed on the basis of evidence-based medicine and focuses on unique treatments in Japan that have not been included in the Surviving Sepsis Campaign guidelines (SSCG), as well as treatments that are viewed differently in Japan and in Western countries. Although the methods in this guideline conform to the 2008 SSCG, the Japanese literature and the results of the Sepsis Registry Survey, which was performed twice by the Sepsis Registry Committee in intensive care units (ICUs) registered with JSICM, are also referred. This is the first and original guideline for sepsis in Japan and is expected to be properly used in daily clinical practice.

This article is translated from Japanese, originally published as “The Japanese Guidelines for the Management of Sepsis” in the Journal of the Japanese Society of Intensive Care Medicine (J Jpn Soc Intensive Care Med), 2013; 20:124–73. The original work is at http://dx.doi.org/10.3918/jsicm.20.124.

Renal recovery after acute kidney injury: choice of initial renal replacement therapy modality still matters

Renal replacement therapy can be applied either in an intermittent fashion or in a continuous fashion in severe acute kidney injury. To date, no modality has been shown to consistently improve patient survival. In the study recently reported by Sun and colleagues, continuous application of renal replacement therapy was associated with improved renal recovery, defined by lower risk of long-term need for chronic dialysis therapy. This association between nonrecovery and intermittent renal replacement therapy may be explained by a higher rate of hypotensive episodes and the lower capacity for fluid removal during the first 72 hours of therapy. Altogether, this study adds to the growing body of evidence to suggest improved likelihood of recovery of kidney function in critically ill survivors of AKI with continuous modalities for renal replacement therapy.

The association between renal replacement therapy modality and long-term outcomes among critically ill adults with acute kidney injury: a retrospective cohort study*

OBJECTIVE

Among critically ill patients with acute kidney injury, the impact of renal replacement therapy modality on long-term kidney function is unknown. Compared with conventional intermittent hemodialysis, continuous renal replacement therapy may promote kidney recovery by conferring greater hemodynamic stability; yet continuous renal replacement therapy may not enhance patient survival and is resource intense. Our objective was to determine whether continuous renal replacement therapy was associated with a lower risk of chronic dialysis as compared with intermittent hemodialysis, among survivors of acute kidney injury.

DESIGN

Retrospective cohort study.

SETTING

Linked population-wide administrative databases in Ontario, Canada.

PATIENTS

Critically ill adults who initiated dialysis for acute kidney injury between July 1996 and December 2009. In the primary analysis, we considered those who survived to at least 90 days after renal replacement therapy initiation.

INTERVENTIONS

Initial receipt of continuous renal replacement therapy versus intermittent hemodialysis.

MEASUREMENTS AND MAIN RESULTS

Continuous renal replacement therapy recipients were matched 1:1 to intermittent hemodialysis recipients based on a history of chronic kidney disease, receipt of mechanical ventilation, and a propensity score for the likelihood of receiving continuous renal replacement therapy. Cox proportional hazards were used to evaluate the relationship between initial renal replacement therapy modality and the primary outcome of chronic dialysis, defined as the need for dialysis for a consecutive period of 90 days. We identified 2,315 continuous renal replacement therapy recipients of whom 2,004 (87%) were successfully matched to 2,004 intermittent hemodialysis recipients. Participants were followed over a median duration of 3 years. The risk of chronic dialysis was significantly lower among patients who initially received continuous renal replacement therapy versus intermittent hemodialysis (hazard ratio, 0.75; 95% CI, 0.65-0.87). This relation was more prominent among those with preexisting chronic kidney disease (p value for interaction term = 0.065) and heart failure (p value for interaction term = 0.035).

CONCLUSIONS

Compared with intermittent hemodialysis, initiation of continuous renal replacement therapy in critically ill adults with acute kidney injury is associated with a lower likelihood of chronic dialysis.

Acute kidney injury-epidemiology, outcomes and economics

Acute kidney injury (AKI) is a widespread problem of epidemic status. Compelling evidence indicates that the incidence of AKI is rapidly increasing, particularly among hospitalized patients with acute illness and those undergoing major surgery. This increase might be partially attributable to greater recognition of AKI, improved ascertainment in administrative data and greater sensitivity of consensus diagnostic and classification schemes. Other causes could be an ageing population, increasing incidences of cardiovascular disease, diabetes mellitus and chronic kidney disease (CKD), and an expanding characterization of modifiable risk factors, such as sepsis, administration of contrast media and exposure to nephrotoxins. The sequelae of AKI are severe and characterized by increased risk of short-term and long-term mortality, incident CKD and accelerated progression to end-stage renal disease. AKI-associated mortality is decreasing, but remains unacceptably high. Moreover, the absolute number of patients dying as a result of AKI is increasing as the incidence of the disorder increases, and few proven effective preventative or therapeutic interventions exist. Survivors of AKI, particularly those who remain on renal replacement therapy, often have reduced quality of life and consume substantially greater health-care resources than the general population as a result of longer hospitalizations, unplanned intensive care unit admissions and rehospitalizations.

How to choose the ideal renal replacement therapy in sepsis?

Sepsis is the main cause of acute kidney injury (AKI) among individuals hospitalized in intensive care units. Acute kidney injury is an independent risk factor for mortality, and its occurrence increases the complexity and cost of treatment. However, the pathophysiological mechanisms of AKI remain unclear. Hemodynamic, vascular, tubular, cellular, inflammatory, and oxidative processes are involved. Individuals with AKI generally have various comorbidities and are elderly and hypercatabolic and on vasopressors and mechanical ventilation. Dialysis is the main treatment for AKI. Although there is no clear benefit of any specific dialysis modality, these patients are initially instructed to use continuous dialysis methods, especially for the most severe cases with multiple organ system dysfunctions and for those who display signs of hemodynamic instability. Recent studies demonstrate that patients should receive a dialysis dose of at least 25 mL · kg · h.

Acute kidney injury and critical cardiac disease

The field of cardiac intensive care continues to advance in tandem with congenital heart surgery. The survival of patients with critical congenital heart disease is seldom in question. Consequently, the focus has now shifted to that of morbidity reduction and eventual elimination. Acute kidney injury (AKI) after cardiac surgery is associated with adverse outcomes, including prolonged intensive care and hospital stays, diminished quality of life, and increased long-term mortality. Acute kidney injury occurs frequently, complicating 30% to 40% of adult and pediatric cardiac surgeries. Patients who require dialysis are at high risk of mortality, but even minor degrees of postoperative AKI portend a significant increase in mortality and morbidity.

Outcomes and characteristics of intermittent hemodialysis for acute kidney injury in an intensive care unit

Renal replacement therapy in intensive care units (ICUs) varies globally and is dependent on medical and non-medical factors. We performed a retrospective analysis of patients initiated on dialysis in an ICU. Patient and clinical characteristics, cause of kidney injury, laboratory parameters, hemodialysis characteristics, and survival were reviewed. Acute physiological and chronic health (APACHE II) score was use to study the sickness profile. A total of 92 patients underwent 525 hemodialysis sessions. There were 60 male and 32 female patients. The mean age of the patients was 56.5 ± 16 years. The cause of acute kidney injury included sepsis 64, cardiac 7, malaria 7, postoperative 4, trauma 3, poisoning 2, and others 4. Vasopressors were used in 75% and mechanical ventilation was used in 74 (82%) of the cases. APACHE II score was 22.3 + 7.4. The mean creatinine level was 3.6 + 3.7 mg/dl. The duration of dialysis was less than 4 h in 324 (61.2%) sessions and greater than 6 h in 118 (22.5%) sessions. The percentage of 30-day survival was 30%. Intermittent hemodialysis customized to renal support needs of ICU patients is an appropriate option in resource-limited settings.

Choice of renal replacement therapy modality and dialysis dependence after acute kidney injury: a systematic review and meta-analysis

PURPOSE

Choice of renal replacement therapy (RRT) modality may affect renal recovery after acute kidney injury (AKI). We sought to compare the rate of dialysis dependence among severe AKI survivors according to the choice of initial renal replacement therapy (RRT) modality applied [continuous (CRRT) or intermittent (IRRT)].

METHODS

Systematic searches of peer-reviewed publications in MEDLINE and EMBASE were performed (last update July 2012). All studies published after 2000 reporting dialysis dependence among survivors from severe AKI requiring RRT were included. Data on follow-up duration, sex, age, chronic kidney disease, illness severity score, vasopressors, and mechanical ventilation were extracted when available. Results were pooled using a random-effects model.

RESULTS

We identified 23 studies: seven randomized controlled trials (RCTs) and 16 observational studies involving 472 and 3,499 survivors, respectively. Pooled analyses of RCTs showed no difference in the rate of dialysis dependence among survivors (relative risk, RR 1.15 [95 % confidence interval (CI) 0.78-1.68], I(2) = 0 %). However, pooled analyses of observational studies suggested a higher rate of dialysis dependence among survivors who initially received IRRT as compared with CRRT (RR 1.99 [95 % CI 1.53-2.59], I (2) = 42 %). These findings were consistent with adjusted analyses (performed in 7/16 studies), which found a higher rate of dialysis dependence in IRRT-treated patients [odds ratio (OR) 2.2-25 (5 studies)] or no difference (2 studies).

CONCLUSIONS

Among AKI survivors, initial treatment with IRRT might be associated with higher rates of dialysis dependence than CRRT. However, this finding largely relies on data from observational trials, potentially subject to allocation bias, hence further high-quality studies are necessary.

Fluid management in acute kidney injury

Fluid management in critical illness has undergone extensive reevaluation in the past decade. Since a significant percentage of critically ill patients develop acute kidney injury (AKI), optimal fluid management is even more paramount to prevent the ill effects of either underhydration or overhydration. The concepts of early goal-directed fluid therapy (EGDT) and conservative late fluid management permeate current clinical research, and the independent association between fluid accumulation and mortality has been repeatedly demonstrated. A number of prospective randomized trials are planned to provide an adequately powered assessment of the effect of EGDT or earlier renal replacement therapy initiation in patients with, or at risk for AKI. The aim of this analytical review is to use existing clinical and physiological studies to support a 3-phase model of fluid management in the critically ill patient with AKI.